Lidé

prof. Ing. Jan Macháč, DrSc.

Všechny publikace

Constraints of Using Conductive Screen-Printing for Chipless RFID TAGs with Enhanced RCS Response

  • DOI: 10.3390/app13010148
  • Odkaz: https://doi.org/10.3390/app13010148
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The analysis and experimental verification of the properties of four types of chipless RFID tags with increased RCS response level designed and fabricated by conductive screen printing by silver paste on foil and paper substrates was performed. The analytical formula for the quality factor of microstrip structures with reduced conductivity of metal layers was used to predict the changes and detectability of the backscattered RCS response. The analysis provides insight into the limitations and outlines the possibilities of chipless structures screen-printed on foil and pa-per substrates, which can be of significant benefit to further reduce the cost and speed up the production of these tags for identification and sensing purposes.

Design and Modeling of An Axisymmetric Eddy Current Sensor for Speed Measurement of Nonmagnetic Rods

  • DOI: 10.1016/j.sna.2022.113728
  • Odkaz: https://doi.org/10.1016/j.sna.2022.113728
  • Pracoviště: Katedra elektromagnetického pole, Katedra měření
  • Anotace:
    This paper presents the design and modeling of an eddy current speed sensor for nonmagnetic moving rods with an axisymmetric configuration. The sensor consists of two antiserially connected excitation coils and one pick up coil located between two excitation coils. A novel computational approach using the combined finite difference method and Fourier series is proposed for the modeling and simulations of the eddy current speed sensor. The effects of the outer diameters of moving nonmagnetic rods and their electrical conductivities on the performance of speed sensor are originally evaluated. The results of the modeling for the eddy current speed sensor are compared with the measurements at time varying speeds and various frequencies. The comparison between modeling and experimental results shows the appropriateness of the eddy current speed sensor for the speed measurement of nonmagnetic rods.

Proof of Concept of Reconfigurable Solvent Vapor Sensor Tag with Wireless Power Transfer for IoT Applications

  • DOI: 10.3390/app122010266
  • Odkaz: https://doi.org/10.3390/app122010266
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, a concept of reconfigurable chipless Radio Frequency Identification (RFID) sensor tag for detecting solvent vapors/gas in IoT applications was presented. The concept is based on authors previously published rectangular loop structure equipped with a U-folded dipole loaded with a glide-symmetrical interdigital capacitor coated with a thin layer of tetrasulfonated copper phthalocyanine deposited as a sensing layer to improve the sensing capability in the presence of acetone vapor. In order to further maximize the sensitivity of the designed structure to the de-sired solvent, a circuit for a central frequency adjust using a radio frequency varactor diode bi-ased with a wireless power transfer (WPT) was designed. By varying the DC bias of the diode, a continuous tunable range of approximately 200 MHz was achieved. The proposed reconfigurable wireless sensor tag was manufactured and the frequency shift was verified by measurement. The proposed external frequency control can be applied to a wide class of electrical resonators.

Remote Tuning of Resonant Circuits Using Wireless Power Transfer

  • Autoři: Ayadi, H., prof. Ing. Jan Macháč, DrSc., Ing. Milan Švanda, Ph.D., Boulejfen, N., Latrach, L.
  • Publikace: 2022 Asia-Pacific Microwave Conference Proceedings. Tokyo: IEICE, Institute of Electronics, Information and Communication Engineers, 2022. p. 946-948. ISBN 978-4-902339-54-3.
  • Rok: 2022
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The resonant frequency of a solvent vapor sensor tag has been made adjustable through the use of a RF varactor diode biased using wireless power transfer. Varying the DC bias of the diode provided a continuous tuning range of about 200 MHz. The proposed external frequency control can be applied to a wide class of electric resonators used in passive systems without an energy source. The proposed reconfigurable wireless resonant circuit was manufactured and the measured results agree well with the simulations.

A Novel Compact Substrate Integrated Waveguide Filter Using Miniaturized Stepped Impedance Metamaterial Unit Cell

  • Autoři: prof. Ing. Jan Macháč, DrSc., Troudi, Z., Osman, L.
  • Publikace: Progress in Electromagnetics Research C. 2021, 108 49-61. ISSN 1937-8718.
  • Rok: 2021
  • DOI: 10.2528/PIERC20111401
  • Odkaz: https://doi.org/10.2528/PIERC20111401
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A novel substrate integrated waveguide bandpass filters are presented by using a complementary split-ring resonator. The proposed stepped impedance octagonal complementary split-ring resonator (SI-OCSRR) presents high miniaturization compared to the classical octagonal complementary split-ring resonator (O-CSRR). Additionally, two different filter configurations consisting of two cascaded cells with different coupling between the CSRR are proposed. A comparison between the proposed filters and the other ones reported in the literature has proven the advantages of the proposed filters, namely compact size, high in-band return loss, and ease of integration. A good agreement between the simulated and measured results has been reached, which verifies the validity of the design methodology.

Impact of Thermal Shielding on Heating Efficiency of SiC in Single Mode Microwave Resonant Cavity

  • Autoři: Cichon, S., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of the CPEE 2021 - 22th International Conference "Computational Problems of Electrical Engineering". Plzeň: University of West Bohemia, 2021. ISBN 978-1-7281-8430-2.
  • Rok: 2021
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Microwave heating of a susceptor in the form of SiC disc was simulated in a single mode resonant cavity. The microwave applicator consisted of a waveguide of rectangular cross section WR340 excited by dominant TE10 mode at the industrial frequency 2.45 GHz. Heating efficiency was investigated in two principal configurations represented by 1) an exposed susceptor and 2) a susceptor surrounded with thermal shielding in the form of three coaxial tubes of microwave transparent ceramics. It was found that a relatively high value of the real part of dielectric permittivity of the insulation ceramics leads to a non-negligible modification of the field pattern inside the cavity. This could significantly improve heating efficiency. Consequently, for the design of an efficient microwave applicator, actual sample as well as insulation geometry and dielectric properties should be highly regarded. The analysis has been supported by experiment.

Planar Hexagonal Antenna with dual Reconfigurable Notched Bands for Wireless Communication Devices

  • Autoři: Ayadi, H., prof. Ing. Jan Macháč, DrSc., Latrach, L., Beldi, S.
  • Publikace: Radioengineering. 2021, 2021(1), 25-33. ISSN 1805-9600.
  • Rok: 2021
  • DOI: 10.13164/re.2021.0025
  • Odkaz: https://doi.org/10.13164/re.2021.0025
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, a planar hexagonal antenna with dual tunable notched band using varactor diodes is presented. The designed antenna operates in the frequency range of 2 GHz to 8 GHz and is loaded by a complementary split ring resonator (CSRR) to achieve the notch-band characteristics. The CSRR produced two stop-bands at the frequencies 3 GHz and 6.8 GHz. In order to obtain the reconfigurability, one varactor diode was used on each ring of the CSRR. The variation of the DC bias of the diodes produced double notched bands yielding a tunable coverage in the 0.6 GHz and 1.6 GHz ranges. The continuous agility and the wide tuning range of the notched bands are the major advantages of this structure. The antenna prototype was manufactured and a good agreement has been achieved between the measured and simulated results. The proposed antenna can be a good candidate for wireless applications that cover the UMTS, the Wi-Fi and the WiMAX bands.

Chipless RFID Tag with Enhanced RCS Used as a Phthalocyanine-Based Solvent Vapors Sensor

  • DOI: 10.1109/LAWP.2020.3009453
  • Odkaz: https://doi.org/10.1109/LAWP.2020.3009453
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A novel uniplanar chipless RFID solvent vapors/gas sensor is proposed in this paper. The sensor etched on an extremely thin capton substrate is composed of the folded dipole resonator loaded by the interdigital capacitor located inside the planar rectangular metallic loop that improves the RCS response. When illuminated by a plane wave, the folded dipole causes a notch in the RCS response of the loop located near its resonant frequency. The high RCS level (-18 dBsm), together with the notch depth (16 dB) assure a reliable detection of its position within the frequency dependence of RCS curve. In order to enhance the structure sensitivity to the presence of acetone vapors, the tetrasulfonated copper phthalocyanine thin film was applied as a sensitive layer during the process of folded dipole metallization. The experimental verification confirmed the viability of sensor proof-of-concept for the detection of chemical vapors.

Compact dual-band bandpass filter using a modified hexagonal split ring resonator

  • Autoři: Troudi, Z., prof. Ing. Jan Macháč, DrSc., Osman, L.
  • Publikace: Microwave and Optical Technology Letters. 2020, 62(5), 1893-1899. ISSN 0895-2477.
  • Rok: 2020
  • DOI: 10.1002/mop.32258
  • Odkaz: https://doi.org/10.1002/mop.32258
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this article, a compact dual-band bandpass filter (BPF) is studied and designed by utilizing a modified hexagonal split ring resonator (H-SRR). The modified H-SRR consists of a classical H-SRR loaded by an open-stepped impedance stub and a grounding via located at the symmetrical plane of the resonator. The proposed BPF operates at 2.5 and 4.83 GHz. Its advantages include simplicity of design, high rejection level due to transmission zeros, and low insertion loss. In addition, the size of the circuit occupies only 142.6 mm(2). A good agreement is obtained between measurement and simulation results.

Design of a flat-type magnetic position sensor using a finite-difference method

  • DOI: 10.1049/iet-smt.2019.0197
  • Odkaz: https://doi.org/10.1049/iet-smt.2019.0197
  • Pracoviště: Katedra elektromagnetického pole, Katedra měření
  • Anotace:
    This study presents an analysis and the design of a new flat-type position sensor with an external armature. One excitation coil and two antiserially connected pickup coils are used in the stationary part. Solid iron segments or steel lamination segments are used for the moving armature. The proposed position sensor was modelled using linear movement. A two-dimensional finite-difference method was developed and was used for fast analysis for optimising the sensor. The induced eddy currents in the solid armature were taken into account in the finite-difference analysis. The finite-difference calculations were compared with 2D and 3D finite-element method simulations and with experimental results. The sensor has a total error of 0.23 mm root-mean-square for 36 mm range without any compensation. Unlike previous designs, the authors’ new sensor has no moving coil.

The First IEEE Milestone in Ukraine Celebrates "Zenit Parabolic Reflector L-Band Pulsed Radar, 1938" in Kharkiv

  • Autoři: Arkhypova, K., prof. Ing. Jan Macháč, DrSc., Pesina, D.
  • Publikace: IEEE Microwave Magazine for the Microwave and Wireless Engineer. 2020, 21(8), 98-101. ISSN 1527-3342.
  • Rok: 2020
  • DOI: 10.1109/MMM.2020.2993485
  • Odkaz: https://doi.org/10.1109/MMM.2020.2993485
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    On 21 November 2019, a commemorative plaque recognizing the IEEE Milestone “Zenit Parabolic Reflector L-band Pulsed Radar, 1938” was unveiled at the School of Radiophysics, Biomedical Electronics, and Computer Systems at the V.N. Karazin Kharkiv National University (KhNU).

Experimental Verification of the Behavior of a Double Negative Metamaterial Composed of Planar Resonant Elements

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: 2019 International Microwave Symposium. IEEE MTT-S, 2019. p. 889-892. ISSN 0149-645X. ISBN 978-1-7281-1309-8.
  • Rok: 2019
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Measurement of the behavior of double negative volumetric metamaterials is presented in this paper. These metamaterials are composed of planar resonant elements that show negative electric and magnetic polarizabilities. The first metamaterial is a regular 3D periodic structure. The second metamaterial is an analog of an amorphous solid material. The resonant elements are randomly located in space, both in their positions and in their orientation. Planar resonators are inserted into polystyrene spheres to assure their fully random distribution in the space. This has the advantage that the spheres can fill any volume keeping a random distribution of resonant particles. This composite material shows an isotropic response, as it does not prefer any direction of wave propagation. The measurements verified that metamaterials of both types behave as a double negative metamaterial within a narrow frequency band.

Low-profile Slotted SIW Cavity Backed Antenna

  • DOI: 10.13164/re.2019.0386
  • Odkaz: https://doi.org/10.13164/re.2019.0386
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The agile frequency antennas are widely used for wireless communication systems. This paper studies and designs a low-profile SIW antenna radiating from a circular slot graved in the ground plane, with the ability of alternating the frequency. The antenna is intentionally designed within a range of 1.8 GHz to 2.18 GHz obtained by varying the DC bias voltages from 0 to 26 V, which is able to cover the GSM1800, the LTE, and the UMTS wireless standards. The tuning technique consists in the integration of two varactor diodes across the circular slot. A prototype was manufactured, and the experiment results correspond well to those of the simulations.

Miniaturised planar band-pass filter based on interdigital Arm SRR

  • Autoři: Troudi, Z., prof. Ing. Jan Macháč, DrSc., Osman, L.
  • Publikace: IET Microwaves, Antennas & Propagation. 2019, 12(13), 2081-2086. ISSN 1751-8725.
  • Rok: 2019
  • DOI: 10.1049/iet-map.2018.5708
  • Odkaz: https://doi.org/10.1049/iet-map.2018.5708
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Here, a small-size band-pass filter is designed using a new split-ring resonator (SRR). First, the geometric optimisation method is used to obtain the high miniaturisation of the proposed SRR compared to the conventional structures. Accordingly, the reduction rate has reached 51%. The second part of this study is devoted to the development of a band-pass filter using the proposed SRR topology. A Chebyshev-type band-pass filter has been designed. The purpose is to have a miniaturised structure, low insertion loss, and high out off-band rejection. This filter is composed of two integrated arms SRR placed in series with a defected ground structure (DGS) to increase the coupling between the resonators, and a low-pass filter integrated into the resonators to improve the level of rejection. The resonance frequency has been approximately measured at 1 GHz and the size has been valued at 0.114λg × 0.083λg, thus achieving miniaturisation up to 78% compared fabricated and experimentally validated. The measured insertion loss has been found to 0.8 dB and two transmission zeros helped to ensure the steep sides of the transmission band.

Platform Tolerant, High Encoding Capacity Dipole Array-Plate Chipless RFID Tags

  • DOI: 10.1109/ACCESS.2019.2935258
  • Odkaz: https://doi.org/10.1109/ACCESS.2019.2935258
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, we first carry out an in-depth review of the performance parameters of frequency domain chipless RFID transponders in terms of their spatial density, spectral capacity, and comprehensive encoding capacity (bit/lambda2/GHz) comprising both spatial and spectral performance, and platform tolerance. Secondly, we theoretically and numerically investigate the recently introduced and promising concept of the platform-tolerant chipless RFID transponder based on a detuned dipole array-plate that provides high encoding capacity. We propose, fabricate and measure a 20-bit transponder consisting of an array of 20 detuned dipoles closely coupled to a 60 × 60 mm2 metallic plate. The radar cross section at the level of 15 dBsm exhibits reliably recognizable minima corresponding to individual dipole resonances. When compared to other published frequency-domain chipless RFID transponders, the encoding capacity reaches 47.4 bit/lambda2/GHz, which constitutes one of the highest values, while achieving a concurrently high level of radar cross section (RCS) reflection response and platform tolerance performance. The measurements confirm very good performance parameters in the cases when the transponder is attached to various packaging materials, such as cardboard, plastic, wood, metal or a human body phantom. The essential benefits of the presented solution include a very good frequency and amplitude stability in the RCS response, which enables a reliable reading of encoded information (if zero bits are coded). The double layer metallization represents an inherent property of the proposed solution, which is a necessary trade-off for high encoding capacity and contemporary platform tolerance.

UWB MIMO Antenna for High Speed Wireless Applications

  • Autoři: Ibrahim, Ahmed A., prof. Ing. Jan Macháč, DrSc., Shubair, Raed M.
  • Publikace: Applied Computational Electromagnetics Society Journal. 2019, 34(9), 1294-1299. ISSN 1054-4887.
  • Rok: 2019
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper proposes a MIMO antenna composed of two elements in the form of UWB monopole antennas. Polarization diversity of the proposed antenna is obtained locating the two elements perpendicularly on a common substrate. Also the isolation between elements is accomplished without using any extra decoupling structures. The two monopoles antennas with half elliptical shape are fed with asymmetric coplanar strip (ACS). The presented antenna is located on substrate 48 x 28 mm(2) in total size. The distance between the two elements is 15 mm that is 0.15 lambda(0) at 3GHz. The antenna was designed to work effectively from 3 to 11.5 GHz with reflection coefficient better than -10 dB and isolation lower than 18 dB. In addition, antenna with elements located in parallel was designed to show the advantage of the original design. Envelope correlation coefficient, diversity gain and channel capacity loss document the antennas behavior. The antenna was fabricated and measured. Measurement validated the simulation and showed that the designed antenna can be well applied in UWB MIMO systems.

A Negative Permittivity Metamaterial Composed of Planar Resonators with Randomly Detuned Resonant Frequencies and Randomly Distributed in Space

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: International Journal of Microwave and Wireless Technologies. 2018, 10(9), 1028-1034. ISSN 1759-0787.
  • Rok: 2018
  • DOI: 10.1017/S1759078718001046
  • Odkaz: https://doi.org/10.1017/S1759078718001046
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper investigates metamaterials composed of resonant particles with negative electric polarizability located in a 3D net. The main problem in fabricating of these materials is the spread of the resonant frequencies of particular planar resonators. This spread is caused by the tolerances of the fabrication process for planar resonators. Simulation shows that there is a limit to the dispersion of resonant frequencies that allow the metamaterial to behave as a metamaterial with negative effective permittivity. Two metamaterials with a negative real part of the effective permittivity were designed on the basis of simulations. The first metamaterial has a regular periodic structure. The second is a metamaterial in which the resonant particles are randomly distributed both in space and in orientation, and it offers an isotropic response. This metamaterial was fabricated by inserting planar resonators into plastic shells that can be poured into any volume and ensure random distribution of the resonant particles in space. The results of the simulations have been verified by measurements.

Development of SIW LWA from non-uniform CRLH unit cells with SLL reduction

  • Autoři: Noumi, R., prof. Ing. Jan Macháč, DrSc., Boulajefan, N., Gharsallah, A.
  • Publikace: 2018 18th Mediterranean Microwave Symposium (MMS 2018). IEEE (Institute of Electrical and Electronics Engineers), 2018. p. 146-148. vol. 1. ISSN 2157-9822. ISBN 978-1-5386-7132-0.
  • Rok: 2018
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this communication, we propose an improved SIW LWA based on non-uniform CRLH unit cells. The antenna consists of 5 sections with changing the number of interdigital fingers of the unit cells. This configuration allows the reduction of the side lobe level. In addition, a high gain value around 15 dB is obtained over the frequency bandwidth from 9 to 13.4 GHz. The main beam of the proposed design scans from -52 to 64 degrees and a high radiation efficiency with an average of 95% is found on the frequency band.

Frequency-Domain Chipless RFID Transponders: Improvement the Reading Response

  • DOI: 10.23919/MIKON.2018.8405332
  • Odkaz: https://doi.org/10.23919/MIKON.2018.8405332
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper reviews investigations of the authors in the field of frequency-domain chipless RFID transponders. The main issue is to reduce the mutual coupling between adjacent resonant elements in the scatterer array to ensure the robust RCS response for reliable reading of coded information. A major improvement in RCS response of transponders is proposed, using slot-in-plate type transponders. Advantages and drawbacks of the proposed solutions are discussed and several open challenges in the field are emphasized.

Influence of Mutual Coupling on Stability of RCS Response in Chipless RFID

  • DOI: 10.3390/technologies6030067
  • Odkaz: https://doi.org/10.3390/technologies6030067
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper investigates the influence of mutual coupling between individual scatterings of chipless Radio Frequency Identification (RFID) tags based on its frequency-domain performance using a simplified equivalent circuit model. The proposed steady state analysis predicts a fast and satisfactory amplitude level and frequency position of resonant peaks of a predicted radar cross section (RCS) response. The proposed approach is capable of pre-evaluating a suitability of the particular scattered topology for implementing in chipless RFID tags. It is demonstrated on two different geometries.

Novel Single/Dual Beam Scanning Provided by an Array Composed of Two CRLH SIW LWAs

  • Autoři: Noumi, R., prof. Ing. Jan Macháč, DrSc., Gharsallah, A.
  • Publikace: Proceedings of the 48th European Microwave Week. Louvain-la-Neuve: European Microwave Association (EuMA), 2018. p. 380-383. ISBN 978-2-87487-051-4.
  • Rok: 2018
  • DOI: 10.23919/EuMC.2018.8541800
  • Odkaz: https://doi.org/10.23919/EuMC.2018.8541800
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A novel single/dual beam switchable steering of dual different elements CRLH LWAs has been introduced in this communication. This structure with two phased feeding ports is designed on a SIW technology with only one via walls that associates both structures. The fabricated prototype features a complex beam scanning from -72° to 73° by sweeping the frequency from 6.9 to 13.4 GHz. Radiation performances are obtained by measuring the antenna in an anechoic chamber, results show a pick gain of 15.4 dB and high radiation efficiency with an average 90 %. This design suitable for tracking applications and smart monitoring systems.

Polarisation Independent Chipless RFID Tag Based on Circular Arrangement of Dual-Spiral Capacitively-Loaded Dipoles with Robust RCS Response

  • DOI: 10.1049/iet-map.2018.5434
  • Odkaz: https://doi.org/10.1049/iet-map.2018.5434
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper deals with the novel polarisation independent 20-bit chipless RFID transponder that is based on a circularly arranged array of electrically small dual-spiral capacitively-loaded dipole scatterers with improved robustness of RCS response. A single scatterer exhibits a better performance in terms of electrical size and radar cross section (RCS) than the earlier introduced U-dipole type scatterers occupying the same footprint area. In order to investigate the frequency stability and amplitude uniformity of RCS curve, two arrangements of scatterer arrays were analyzed: rearranged side-by-side and circular. In comparison to the other arrangements, the latter provides an excellent amplitude RCS stability over the whole operational frequency band and, at the same time enables the polarization independence of identification. However, it requires the two-channel orthogonal polarization measurement.

Region 8 MTT-S Chapter Representatives October 2017 Meeting

  • Autoři: prof. Ing. Jan Macháč, DrSc., Pasquet, D.
  • Publikace: IEEE Microwave Magazine for the Microwave and Wireless Engineer. 2018, 96-99. ISSN 1527-3342.
  • Rok: 2018
  • DOI: 10.1109/MMM.2017.2781039
  • Odkaz: https://doi.org/10.1109/MMM.2017.2781039
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The annual meeting of the IEEE Microwave Theory and Techniques Society (MTT-S) Chapter representatives takes place in conjunction with European Microwave Week (EuMW), the most prestigious microwave event in Europe. In 2017, EuMW was held at the Nuremberg Convention Center, Germany, 8–13 October. The Chapter chairs’ meeting (CCM) took place at Le Méridien Grand Hôtel Nuremberg on Monday, 9 October, starting at 3:00 p.m.

Semi-Platform Tolerant 20-bit Chipless RFID Tag Composed of Dipole Array Closely Coupled to Plate

  • DOI: 10.1049/cp.2018.0482
  • Odkaz: https://doi.org/10.1049/cp.2018.0482
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper novel semi-platform tolerant 20-bits chipless RFID tag based on array of dipoles closely coupled to metallic plate of the size 60 × 60 mm is presented. Quality factor of single dipole-plate is analysed to better understand the resonant behavior of the scatterer. RCS response level about 15 dBsm, spectral bit capacity > 15 bit/GHz and good frequency and amplitude stability of the RCS represent promising solution for chipless RFID systems.

Space Leaky Waves Propagating along a Pair of CRLH SIW Lines

  • DOI: 10.13164/re.2018.0633
  • Odkaz: https://doi.org/10.13164/re.2018.0633
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A space leaky wave excited on composite rightleft handed substrate integrated waveguide and radiating in a wide frequency band is presented in this paper. The proposed two line array is a good candidate for smart systems of monitoring and tracking applications. The system is composed of two different lines that are placed in parallel on the same substrate. Simulation results show that the first line leaks energy in the band from 6.9 to 11 GHz with a 7.8 GHz broadside radiation frequency and the second line leaks in the band from 8.9 to 13.8 GHz; the related broadside radiation frequency is 10.2 GHz. Complex single/dual scanned beams are obtained in a wide range of angles from –72° to +73°. The simulations were carried out in the CST Microwave Studio and the obtained measurement results match well with the theoretical analysis described in this paper.

Volumetric Double Negative Metamaterial Composed of Planar

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: 2018 IEEE/MTT-S International Microwave Symposium - IMS. IEEE MTT-S, 2018. p. 30-32. ISSN 2576-7216.
  • Rok: 2018
  • DOI: 10.1109/MWSYM.2018.8439379
  • Odkaz: https://doi.org/10.1109/MWSYM.2018.8439379
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper investigates double negative volumetric metamaterials. The first version is a regular 3D periodic structure. This metamaterial does not naturally show an isotropic response. An isotropic response has been obtained for an analog of an amorphous solid material. This metamaterial is composed of planar resonant particles that show negative electric and magnetic polarizabilities. The particles are randomly distributed in space both in their positions and in their orientation. This composite material shows an isotropic response, as it does not prefer any direction of wave propagation. The metamaterial was assembled by inserting planar resonators into polystyrene spheres. The advantage is that the spheres can fill any volume and assure a random distribution of resonant particles both in space and in orientation.

Volumetric Double Negative Metamaterial Composed of Planar Resonators

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of the 2018 IEE/MTT-S International Microwave Symposium. San Francisco: American Institute of Physics and Magnetic Society of the IEEE, 2018. p. 30-32. ISBN 978-1-5386-5067-7.
  • Rok: 2018
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper investigates double negative volumetric metamaterials. The first version is a regular 3D periodic structure. This metamaterial does not naturally show an isotropic response. An isotropic response has been obtained for an analog of an amorphous solid material. This metamaterial is composed of planar resonant particles that show negative electric and magnetic polarizabilities. The particles are randomly distributed in space both in their positions and in their orientation. This composite material shows an isotropic response, as it does not prefer any direction of wave propagation. The metamaterial was assembled by inserting planar resonators into polystyrene spheres. The advantage is that the spheres can fill any volume and assure a random distribution of resonant particles both in space and in orientation.

Amorphous Metamaterial With Negative Permeability

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: IEEE Antennas and Wireless Propagation Letters. 2017, 18(1), 2138-2141. ISSN 1536-1225.
  • Rok: 2017
  • DOI: 10.1109/LAWP.2017.2700234
  • Odkaz: https://doi.org/10.1109/LAWP.2017.2700234
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper investigates a metamaterial composed of ring resonators that are randomly distributed in space both in their positions and their orientation. Such metamaterial behaves as amorphous material with isotropic response. The main problem of the fabrication of this material is the spread of resonant frequencies of particular planar ring resonators. This spread is caused by tolerances of the fabrication process of planar resonators. Simulation shows that there is a limit of the dispersion of resonant frequencies allowing the metamaterial to behave as metamaterial with negative effective permeability. The amorphous metamaterial with negative permeability was fabricated and measurement verified the simulation.

Chipless RFID Tag Based on Electrically Small Spiral Capacitively Loaded Dipole

  • DOI: 10.1109/LAWP.2017.2760059
  • Odkaz: https://doi.org/10.1109/LAWP.2017.2760059
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents the novel 20-bit chipless RFID transponder (tag) based on spiral capacitively loaded dipole scatterers of electrical size ka = 0.47, radar cross section σ = 29.3 dBsm, and bandwidth BW3dB = 20.9 MHz. It outperforms U-folded dipole scatterer (ka = 0.79, σ = 34.3 dBsm, BW3dB = 18.1 MHz) in the first two parameters in exchange for a slight increase in bandwidth. The total tag size (17 × 68 mm2) is roughly half the size of a credit card. The frequency and amplitude stability of its RCS response, when the zero bit information is coded via removal of individual scatterers, is improved by reordering scatterers in the array. The simulated results were verified by the monostatic measurement of tag RCS.

Chipless RFID Tag with an Improved Magnitude and Robustness of RCS Response

  • DOI: 10.1002/mop.30321
  • Odkaz: https://doi.org/10.1002/mop.30321
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper describes properties of a new 20-bit chipless RFID tag of the size 52 × 50 mm2, which exhibits an improved magnitude and robustness of the radar cross section (RCS). The tag is based on a novel slots-in-plate array approach, which is complementary to a typical tag consisting of an array of single resonators. In order to eliminate the detuning effect of the missing or shortening slots representing ‘0’ bit information on the resonances of neighbouring slots signifying ‘1’ bit information, the modification of the inter-element arrangement was proposed. Both ways of ‘0’ bit information coding were studied and compared.

Compact Size UWB Monopole Antenna with Triple Band-Notches

  • DOI: 10.13164/re.2017.0057
  • Odkaz: https://doi.org/10.13164/re.2017.0057
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents triple band notched ultra wide band (UWB) monopole antenna with overall size of 36 × 32 mm2 fed by microstrip transmission line. In order to achieve a good impedance matching from 2.7 GHz to 13.4 GHz, a tapered transition between the rectangular patch and the feeding line is utilized. The three notched frequency bands are accomplished by a defected microstrip structure (DMS) which is inserted in the microstrip feeding line and by an open loop slot etched in the radiating patch. The three band notches are 3.15–4 GHz, 5.7–6.3 GHz and 7.9–8.6 GHz. They prevent the receiving of the signals of IEEE 802.16 WiMAX band, WLAN band, and ITU applications respectively. The UWB antenna was designed and simulated, then fabricated and tested in order to investigate its impedance and radiation characteristics. Good agreement between the simulated and measured data is achieved. The obtained results show that the proposed antenna is convenient for UWB applications.

Compact UWB MIMO Antenna with Asymmetric Coplanar Strip Feeding Configuration

  • Autoři: Ibrahim, A.-A., prof. Ing. Jan Macháč, DrSc., Shubair, R.-M., Ing. Milan Švanda, Ph.D.,
  • Publikace: The 28th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE PIMRC 2017). New Jersey: IEEE, 2017. p. 1-4. ISBN 978-1-5386-3531-5.
  • Rok: 2017
  • DOI: 10.1109/PIMRC.2017.8292768
  • Odkaz: https://doi.org/10.1109/PIMRC.2017.8292768
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    compact UWB MIMO antenna composed of two elements is presented in this paper. The two antenna elements are fed by asymmetric coplanar strip (ACS). The radiator of the single antenna consists of half elliptical shape radiator. The two antenna elements are located side by side on FR4 substrate with size equal to 48 × 28 mm2. The edge to edge distance between the antenna elements is 0.23 λ0 at 3 GHz. The two antenna elements are designed to operate in the UWB frequency band from 3 GHz to 11.5 GHz with return loss lower than -10 dB and isolation lower than -15 dB without using decoupling structures between the elements. The envelope correlation coefficient, diversity gain, and capacity loss which define the performance of MIMO antenna are within the required limits. The proposed antennas has been fabricated and measured. Experimental measurements were obtained and are in good agreement with simulation results, which verify that the proposed antenna is a good candidate for UWB MIMO applications. Moreover, the performance of the MIMO antenna is verified by computing the envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CCL).

COMPACT UWB MIMO ANTENNA WITH PATTERN DIVERSITY AND BAND REJECTION CHARACTERISTICS

  • Autoři: Ibrahim, A.A., prof. Ing. Jan Macháč, DrSc., Shubair, R.M.
  • Publikace: Microwave and Optical Technology Letters. 2017, 59(6), 1460-1464. ISSN 0895-2477.
  • Rok: 2017
  • DOI: 10.1002/mop.30564
  • Odkaz: https://doi.org/10.1002/mop.30564
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This article presents a compact size asymmetric CPW strip-fed UWB two-element MIMO antenna, with notched-band behavior. The single-antenna element of the MIMO configuration is composed of a semi-elliptical patch radiator with asymmetric ground plane. The notched-band behavior of the proposed antenna is achieved by inserting a simple folded stub to the patch radiator. This stub achieves the desired single stop-band from 3.3 to 3.9 GHz for WIMAX. The two-antenna elements are placed orthogonally to achieve pattern diversity which leads to an improved MIMO system performance and enhances the isolation between elements without using any decoupling structures. The antenna has dimensions of 50 3 28 mm2. The edge-to-edge distance between antenna elements is 0.15k0 at 3 GHz. The proposed antenna is designed, simulated, fabricated, and tested. Results show that the two-antenna elements operate at frequencies ranging from 2.8 to 11.5 GHz with return loss lower than 210 dB and insertion loss lower than 218 dB. The performance of the MIMO antenna diversity characteristics were verified through the calculation of the standard parameters and show the antenna suitability for MIMO systems. VC 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1460–1464, 2017; View this

Design and Measurement of a Compact UWB MIMO Antenna With Asymmetric Coplanar Strip Feed

  • Autoři: Ibrahim, A.A., prof. Ing. Jan Macháč, DrSc., Shubair, M., Ing. Milan Švanda, Ph.D.,
  • Publikace: Proceedings of International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting. Piscataway, NJ: IEEE, 2017. p. 1655-1656. ISSN 1947-1491. ISBN 978-1-5386-3284-0.
  • Rok: 2017
  • DOI: 10.1109/APUSNCURSINRSM.2017.8072870
  • Odkaz: https://doi.org/10.1109/APUSNCURSINRSM.2017.8072870
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the design and measurement of a two-element MIMO antenna for UWB applications. Feeding for the MIMO antenna is employed using Asymmetric Coplanar Strip (ACS). The two elements are printed side-byside on FR4 substrate, without having to use a decoupling structure between the two antennas. The edge-to-edge separation distance is 0.230 at 3 GHz. The proposed antenna operates in the UWB band from 3 GHz to 11.5 GHz, with a reflection coefficient below -10dB and insertion loss less than - 15dB. The envelope correlation coefficient is under the allowed limits of MIMO systems. The proposed two-element MIMO antenna has been fabricated and measured. Measurement results agree with the simulation results, which verifies the use of the proposed antenna for UWB applications.

Detuned Dipole Array Backed by Rectangular Plate Applied as Chipless RFID Tag

  • DOI: 10.1109/PIERS.2017.8262328
  • Odkaz: https://doi.org/10.1109/PIERS.2017.8262328
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A chipless RFID tag designed as detuned dipole array backed by rectangular plate is proposed. Its main feature is frequency notched RCS response which provides high read range of the tag. Information encoding ability was investigated on three example bit words. It has been found that proposed structure exhibits narrow resonances with higher bit density than other presented structures and thus seems to be a good candidate for compact high density chipless RFID tags. Performance parameters of the structure has been evaluated by EM simulator Zeland IE3D and verified by monostatic measurement in an anechoic chamber.

Erroneous Reading of Information in Chipless RFID Tags

  • DOI: 10.1109/PIERS.2017.8262326
  • Odkaz: https://doi.org/10.1109/PIERS.2017.8262326
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Chipless RFID tags are designed as arrays of planar or uniplanar resonators. These tags should be as small as possible to increase their attraction. On the other hand the closer are particular resonators located the tighter is their coupling. This coupling prevents the reader from proper reading the coded information. This is due to detuning of particular resonant frequencies of resonators and due to changing levels of the resonant peaks. Finally some compromise must be done in the tag design. For error-less reading of information coded by the presence/absence of resonant peaks in the RCS response the proper choice of scatterer topology and their arrangement has significant importance. Simple and efficient way of checking the suitability of particular resonators is presented.

Europe and the Future for WPT COST Action IC1301 Team

  • DOI: 10.1109/MMM.2017.2680078
  • Odkaz: https://doi.org/10.1109/MMM.2017.2680078
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This article presents recent European-based contributions for wireless power transmission (WPT), related to applications ranging from future Internet of Things (IoT) and fifth-generation (5G) systems to highpower electric vehicle charging. The contributors are all members of a European consortium on WPT, COST Action IC1301 (Table 1). WPT is the driving technology that will enable the next stage in the current consumer electronics revolution, including batteryless sensors, passive RF identification (RFID), passive wireless sensors, the IoT, and machine-to-machine solutions.

Region 8 MTT-S Chapter Chair Meeting in London [Around the Globe]

  • Autoři: prof. Ing. Jan Macháč, DrSc., Pasquet, D.
  • Publikace: IEEE Microwave Magazine for the Microwave and Wireless Engineer. 2017, 18(2), 103-106. ISSN 1527-3342.
  • Rok: 2017
  • DOI: 10.1109/MMM.2016.2636679
  • Odkaz: https://doi.org/10.1109/MMM.2016.2636679
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The annual meeting of the MTT-S Chapter Chairs and other Chapter representatives takes place in conjunction with the European Microwave Week (EuMW), the most prestigious microwave event in Europe. In 2016, EuMW was held in the London at ExCel London, October 3-7. The Chapter Chairs’ Meeting (CCM) took place at the Hotel Crowne Plaza London Docklands on Monday October 3 starting at 3 p.m. This friendly meeting brings together Chapter representatives and MTT-S AdCom officers. It provides an opportunity to exchange experience among the individual chapters, to share best practices, to clarify what the chapter wants the officers to do and what IEEE MTT-S administrators should do, to explain the support given to the chapters by MTT-S, and the conditions under which it is provided. In brief, CCM provides an opportunity to teach Chapter Chairs how to run their Chapters.

The MTT-S Region 8 Coordinator's Visit to South Africa

  • Autoři: Geschke, R., prof. Ing. Jan Macháč, DrSc., Stander, T.
  • Publikace: IEEE Microwave Magazine for the Microwave and Wireless Engineer. 2017, 18(5), 122-123. ISSN 1527-3342.
  • Rok: 2017
  • DOI: 10.1109/MMM.2017.2690887
  • Odkaz: https://doi.org/10.1109/MMM.2017.2690887
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The MTT-S is a transnational society with more than 10,500 members and 190 Chapters worldwide. Our Society promotes the advancement of microwave theory and its pplications, including RF, microwave, millimeter-wave, and terahertz technologies. The sentiments expressed here were fully realized during MTT-S Region 8 Coordinator Jan Machac’s visit to South Africa at the invitation of the South Africa MTT-S/IEEE Antennas and Propagation Society (APS)/IEEE Electromagnetic Compatibility (EMC) Society Joint Chapter.

UWB Monopole Antenna with Band Notched Characteristics Mitigating Interference with WiMAX

  • DOI: 10.13164/re.2017.0438
  • Odkaz: https://doi.org/10.13164/re.2017.0438
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented in this paper for operation in ultra wide-band (UWB) applications. The antenna is composed of a semi-elliptical monopole and lateral coplanar ground plane to operate in the UWB range. It occupies a very small size of 28 × 11.5 mm2 and is mounted on low cost FR4 substrate of 1.6 mm thickness and dielectric constant of 4.4. Band notched structure is applied to the proposed antenna to assure the rejection of WiMAX frequency band centered at 3.5 GHz to minimize the interference of the communication system with this service. The radiation characteristic of the proposed ACS-fed monopole antenna is nearly omnidirectional with moderate gain over the entire UWB frequency range. The measurements of the fabricated model confirm the designed behavior. The compactness in size, cheap cost and simple feeding technique make it as a good candidate to be integrated within the portable devices for wireless communication.

3D System of Randomly Detuned Ring Resonators

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of the 16 th International Conference on Mathematical Methods in Electromagnetic Theory. Lviv: Lviv Polytechnic National University, 2016. p. 341-344. ISBN 978-1-5090-1913-7.
  • Rok: 2016
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A homogenization procedure aimed at analyzing a metamaterial designed as a system composed of point magnetic dipoles is presented in this paper. These dipoles represent broad side coupled split ring resonators and/or conducting loops terminated by capacitors. A non-precise fabrication process causes dispersion of the geometrical and material parameters of the resonators, and thus dispersion of their resonance frequencies. The homogenization procedure takes into account random distribution of resonator resonance frequencies with the normal probability distribution. The resonant band of the effective permeability of the metamaterial is significantly widened, the values of both real and imaginary parts of the permeability are reduced. The band of negative permeability real part disappears at high dispersion. The paper also comments on the design of a lens aimed at improving the imaging properties of the MRI system. This lens is composed of cells with cubic symmetry. The proposed homogenization method is verified by measuring the scattering parameters of the metamaterial in a rectangular waveguide, and by proving the isotropic response of the metamaterial of the lens.

A Comparison of Two Ways to Reducing the Mutual Coupling of Chipless RFID Tag Scatterers

  • DOI: 10.1109/MIKON.2016.7491983
  • Odkaz: https://doi.org/10.1109/MIKON.2016.7491983
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents two ways to reduce the mutual coupling between the resonators of the RFID chipless tags. This reduction significantly improves the uniformity of the RCS response of the tag over the operational frequency range from 2 to 4 GHz. The first modification to the tag layout is based on an inter-element rearrangement of the array elements. The second layout modification is based on narrowing the strip width and tapering the longitudinal dipole arms toward the open end. Significantly improved homogeneity of the RCS response in comparison with the original array of folded dipole scatterers was confirmed by simulation and by measurements of 20-bit chipless RFID transponders. The second modification further improves the frequency resolution, which may consequently provide higher encoding capacity in a unit area, but at the expense of a decreased RCS response.

Bezčipová identifikace na radiových kmitočtech (RFID)

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Tématem tohoto příspěvku je bezčipová identifikace na rádiových kmitočtech (chipless RFID). Technologie RFID přináší v posledních letech vyšší úroveň automatizace, která se uplatňuje především v logistice, průmyslu a maloobchodu. Využití však nachází také v medicíně, v knihovnictví a při inventarizaci majetku obecně. Další rozšíření RFID (zejména pro náhradu čárových kódů) závisí na tom, zda se podaří tuto technologii dále zlevnit. Jako řešení tohoto problému se nabízí odstranění nejnákladnější části identifikačního štítku (tagu), kterou je polovodičový čip. Tento příspěvek přináší přehled různých bezčipových řešení.

Capacitively Loaded Dipoles for Chipless RFID Transponder

  • DOI: 10.1109/RADIOELEK.2016.7477349
  • Odkaz: https://doi.org/10.1109/RADIOELEK.2016.7477349
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper proposes a novel uniplanar capacitively loaded dipole-scatterers as building elements for chipless RFID tags with frequency domain coding information. These elements are compared with the known structures in terms of quantities which are crucial for read range (radar cross-section), coding bit capacity (resonance bandwidth), and electrical size. Most suitable type of scatterer was arranged into a 5-bit tag, manufactured and verified by measurement in anechoic chamber.

Implantable Semi-Active UHF RFID Tag With Inductive Wireless Power Transfer

  • DOI: 10.1109/LAWP.2016.2520663
  • Odkaz: https://doi.org/10.1109/LAWP.2016.2520663
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The objective of this paper was to design a compact, battery-less system for an implantable semi-active UHF RFID tag with inductive wireless power transfer for the human body. An RFID chip of the tag, combining powering from a reader by communication and from another source through inductive wireless power transfer, was used. Tag sensitivity for communication was increased by about 21 dB with the help of wireless inductive powering when compared to tags which did not employ this system. Communication and powering circuits were integrated within compact structures on the sides of the reader and the tag. The structure for communication and powering on the side of the reader consists of a centre-excised Archimedes spiral antenna and a circular loop respectively. Similarly, the structure on the side of the tag consists of a folded dipole antenna for communication and a rectangular loop for powering.

Improvement in Robustness and Recognizability of RCS Response of U Shaped Strip-Based Chipless RFID Tags

  • DOI: 10.1109/LAWP.2016.2549638
  • Odkaz: https://doi.org/10.1109/LAWP.2016.2549638
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents significant improvement in robustness and recognizability of RCS response of the two topologicaly rearranged 20-bit U-shaped strip-based tags for spectral signature-based chipless RFID systems. The space rearrangement of individual tag scatterers in the array reduces the inter-element mutual coupling and thus significantly enhances the frequency and amplitude robustness of their radar cross section (RCS). In comparison to the original arrangement of scatterers, the measurement of tags designed for 2 to 4 GHz frequency band showed a significantly improved homogeneity of the RCS curve which results in a more reliable recognition of coded information.

Improvement of Reading Performance of Frequency Domain Chipless RFID Transponders

  • DOI: 10.13164/re.2016.0219
  • Odkaz: https://doi.org/10.13164/re.2016.0219
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This review paper presents the summary of our investigations in several topics of frequency-domain chipless RFID transponders. The performance comparison of various types of scatterers used in the literature and recently proposed by the authors is presented. The issue of proper location of adjacent resonant elements in the scatterer array to reduce the mutual coupling and consequently ensure the robust RCS response for reliable reading of coded information is addressed. A major improvement in RCS response of transponders is proposed, using slot-in-plate type transponders. Advantages and drawbacks of the proposed solutions are discussed and several open challenges in the field are emphasized.

Inductive Wireless Power Transfer for Human Body Implantable UHF RFID Tag

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This contribution deals with a design of a system with RFID communication and inductive wireless powering for a human body implantable tag. A chip of the tag employs powering from an RFID reader by communication and from another source with the help of inductive wireless power transfer. Circuits for communication and powering on the reader and tag sides were designed as compact planar structures. The reader side structure comprises a centre-excised Archimedes spiral antenna for communication and a circular loop for powering. The tag side structure integrates a folded dipole antenna for communication and a rectangular loop for powering. The communication sensitivity of the tag was increased by about 21 dB when the additional inductive wireless powering was used.

Reducing Mutual Coupling in Chipless RFID Tags Composed of U-Folded Dipole Scatterers

  • DOI: 10.1002/mop.30138
  • Odkaz: https://doi.org/10.1002/mop.30138
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    We propose a novel chipless RFID tag composed of topologically modified uniplanar U-folded dipoles with inclined arms. This topology reduces the interelement mutual coupling and provides a significantly better amplitude uniformity and frequency stability of tag RCS response when logical “0” is coded by removing particular scatterers from the array. Simultaneously, it provides a higher encoding capacity in unit frequency range than the arrays composed of original U-folded dipoles with parallel arms, yet at the expense of small RCS magnitude reduction.

Semi-Active 866 MHz RFID Implantable Tag Fed by 6.78 MHz Inductive Wireless Power Transfer

  • DOI: 10.1109/EuMC.2016.7824419
  • Odkaz: https://doi.org/10.1109/EuMC.2016.7824419
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents a compact battery-less semi-active UHF RFID tag powered by an inductive wireless power transfer designed to be implanted into the human body. Communication runs at frequency of 866 MHz whereas powering is performed at frequency of 6.78 MHz to reduce losses. Tag sensitivity for communication was increased by about 21 dB with the help of inductive wireless powering when compared to a tag which did not employ this powering. Communication and powering circuits were integrated within compact structures on the sides of the reader and the tag. The reader side consists of a center-excised Archimedes spiral antenna for communication and a circular loop for powering. The tag side consists of a folded dipole antenna for communication and a rectangular loop for powering.

A System of Split Ring Resonators with Randomly Dispersed Resonance Frequencies

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper reports on a 3D system of broad side coupled split ring resonators with randomly dispersed resonance frequencies. This dispersion is caused by the varied geometric and material parameters of the resonators. The resonance frequency band of the effective permeability of the metamaterial is significantly widened, the value of the real part of the permeability is reduced, or the band of negative permeability even disappears. The paper comments on the design of a lens aimed at improving the imaging properties of the MRI system. The proposed homogenization method is verified by measuring the scattering parameters of the metamaterial in a rectangular waveguide.

Distinguished Microwave Lecturer Round Trip in Central Europe and Balkan Countries

  • Autoři: prof. Ing. Jan Macháč, DrSc., Pedro, J.C.
  • Publikace: IEEE Microwave Magazine for the Microwave and Wireless Engineer. 2015, 16(9), 92-93. ISSN 1527-3342.
  • Rok: 2015
  • DOI: 10.1109/MMM.2015.2453924
  • Odkaz: https://doi.org/10.1109/MMM.2015.2453924
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The discussions hold in Serbia and Romania revealed an avid interest towards IEEE MTT-S and the activities it can promote. Chapter Chairs and other members showed a strong motivation to learn more on the education and networking with international colleagues our professional organization can promote, so that they can improve their teaching institutions, and attract more attention to meetings and small local conferences they are organizing. While the latter motivates already established scholars and practitioners, the former will certainly contribute to counter act against the lack of interest we are all facing in our young people towards science and engineering. With this, Chapter Chairs are increasing the visibility of the IEEE MTT-S, and our Society is helping them promote microwave engineering, and develop their countries. It is highly rewarding to see how the volunteering work of these IEEE members is, indeed, “Advancing Technology for Humanity”. It is with these experiences that we feel the IEEE is doing its job well!

Improvement of RCS Response of U Shaped Strip Based Chipless RFID Tags

  • DOI: 10.1109/EuMC.2015.7345711
  • Odkaz: https://doi.org/10.1109/EuMC.2015.7345711
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    We present a modification of an arrangement of 20-bit chipless tag composed of 20-element array of U-shaped strip scatterers that significantly improves radar cross section response in terms of uniformity and amplitude robustness over the operational frequency range 2 to 4 GHz. This modification is based on the inter-arrangement of array elements in order to eliminate the strong coupling between neighboring resonance elements. The tag has been measured in a mono-static arrangement with one double-ridge horn antenna, and provides a significantly improved homogeneity of the RCS response compared to an original array of folded dipole resonators. The reliability of the reading of coded information is highly improved

Metamaterial Made of BC-SRRs with Randomly Dispersed Resonance Frequencies

  • DOI: 10.1109/MWSYM.2015.7166793
  • Odkaz: https://doi.org/10.1109/MWSYM.2015.7166793
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper reports on an investigation of a metamaterial designed as a 3D system of broad side coupled split ring resonators. Imperfections in the fabrication process cause dispersion of the geometrical and material parameters of the resonators, and thus dispersion of their resonance frequencies. Homogenization of a 3D cubic lattice of these imperfect resonators reveals that the resulting resonance frequency band of the effective permeability is significantly widened, but at the cost of reducing its magnitude or even completely disappearing the negative values of its real part. An experiment performed in the rectangular waveguide verifies the theoretical predictions.

Phase properties of metamaterial elements

  • Autoři: Blaha, M., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of 14th Conference on Microwave Techniques, COMITE 2015. Budapešť: Institute of Electrical and Electronics Engineers Inc., 2015. ISBN 9781479981212.
  • Rok: 2015
  • DOI: 10.1109/COMITE.2015.7120232
  • Odkaz: https://doi.org/10.1109/COMITE.2015.7120232
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the design of a metamaterial in planar form by focusing on the phase properties of its basic elements. These elements must transmit a wave with phase advancement to get a metamaterial showing a negative refractive index. This is obtained by delaying the phase within the basic element by almost-2π, which from outside the element looks like an advancing phase. Simulations demonstrate the behavior of one element, a 1D structure and a 2D structure. The propagating backward wave is traced on terminals of particular elements.

A Polarizability Measurement Method for Electrically Small Particles

  • DOI: 10.1109/LAWP.2014.2327152
  • Odkaz: https://doi.org/10.1109/LAWP.2014.2327152
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A simple and precise free space polarizability measurement method for electrically small particles is presented. The method is based on measuring the scattering parameters of a waveguide loaded by a particle, and on knowledge of the dipolar polarizabilities of two calibration standards. The method is verified on a metallic disk and a resonant conducting ring terminated by a capacitor.

Chipless RFID Tag with an Improved RCS Response

  • DOI: 10.1109/EuMC.2014.6986548
  • Odkaz: https://doi.org/10.1109/EuMC.2014.6986548
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper introduces a new 20-bit chipless RFID tag with an improved radar cross section (RCS), based on a novel complementary approach with the slot-in-plate array with respect to the array of single resonator-based chipless tags. The backscatter pattern is formed by a rectangular metallic plate 52 × 50 mm2 in size etched on a thin dielectric substrate in which an array of 20 shorted coplanar slots is introduced. The originally monotonous RCS frequency response of the rectangular plate exhibits dips corresponding to the presence of individual slots, and thus enables binary coding using amplitude shift keying. The tag has been measured in a bi-static arrangement with two double-ridge horn antennas, and provides a significantly improved overall RCS response compared to an array of resonator-based chipless tags. We also propose two modifications to the inter-arrangement of the slots in order to eliminate the detuning effect of the missing slot representing ‘0’ bit information on the resonances of neighboring slots representing ‘1’ bit information.

Improvement of Backscatter Properties of C-Shaped Dipole Scatterer for Chipless RFID

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper investigates performance properties of arrays of several different C-shaped folded dipole scatterers that are intended to be used as building units (coding particles) for spectral signature based chipless RFID tags. Frequency resolution and uniformity of radar cross section (RCS) response of single scatterers, its triplets and 10-element arrays are investigated. It is found that array of tapered-arms C shaped folded dipole scatterers provides significantly better uniformity of RCS response of the tag and better frequency resolution than the arrays of C-shaped folded dipoles with parallel arms however at the expense of RCS reduction.

Influence of Mutual Coupling on Performance of Small Scatterers for Chipless RFID Tags

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper introduces the two new size-reduced planar scatterers for chipless RFID and explores the influence of mutual coupling of two-element array on their performance. Radar cross section (RCS), and resonant frequency has been evaluated by EM simulation and from S-parameters measured when scatterers have been placed in parallel-plate waveguide. The results clearly show the trade-off between size reduction and RCS proportional to read range of the proposed configurations. Closely spaced resonators are strongly coupled which negatively affects uniformity of their RCS response. Simple geometrical modification of scatterer layout that reduces such unwanted effect is proposed. This results in the development of new smaller uniplanar chipless tags with higher information density.

Microwave Radar Sensor Based on CRLH SIW Leaky-Wave Antennas

  • DOI: 10.1109/EuRAD.2014.6991205
  • Odkaz: https://doi.org/10.1109/EuRAD.2014.6991205
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Modern methods of active defense of military vehicles are based on detection of threat missiles and their elimination by suitable active counter-measures. For these purposes, special radar detection systems are often used. The presented solution employs the SIW based leaky wave antennas which enable detection of the threat missiles in an immediate vicinity of the protected vehicle. The missiles are detected by two tilted detection planes: one main detection plane (as described in [1]), and the other, operating ahead of the main plane. Since the missiles fly through two different planes set under two different angles, system triggering can be improved and more missile parameters can be measured. The sensor structure is relatively simple and occupies merely little space on the surface of the protected vehicle. The performed tests prove functionality of the developed solution.

SIW Leaky Wave Antennas

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: European Microwave Week 2014 Conference Proceedings. London: Horizon House Publications, 2014. p. 448-451. ISBN 978-2-87487-034-7.
  • Rok: 2014
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The substrate integrated waveguide can easily be integrated with planar microwave circuits. Antennas designed on this transmission line have a planar structure, and can be fabricated by a standard PCB technology, so they are suitable for mass production. This paper presents the results of an investigation of leaky wave antennas designed on a substrate integrated waveguide. The interest is given to three antenna types: antenna radiating from a slot in the top waveguide wall, CRLH and dual band CRLH leaky wave antennas.

Substrate Integrated Waveguide – Base for Leaky Wave Antennas

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: European Microwave Week 2014 Conference Proceedings. London: Horizon House Publications, 2014. pp. 1-46. ISBN 978-2-87487-034-7.
  • Rok: 2014
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Antennas designed on the substrate integrated waveguide have a planar structure, and can be easily fabricated by a standard PCB technology, so they are suitable for cheap mass production. This lecture presents the results of an investigation of leaky wave antennas designed on a substrate integrated waveguide. The interest is given to three antenna types: antenna radiating from a wide longitudinal slot etched in the top waveguide wall, SIW CRLH leaky wave antenna, and dual band SIW CRLH leaky wave antenna. These two later antennas radiate through meander slots etched in the top metallization which serve as series capacitors added to design CRLH transmission line.

2012 Gathering of Region 8 Chapter Representatives in Amsterdam

  • Autoři: prof. Ing. Jan Macháč, DrSc., Pasquet, D.
  • Publikace: IEEE Microwave Magazine for the Microwave and Wireless Engineer. 2013, 14(2), 114-118. ISSN 1527-3342.
  • Rok: 2013
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    There are 43 MTT-S Chapters and Joint Chapters in Region 8, including two MTT Student Branch Chapters. The annual meeting of the Chairs and other Chapter representatives takes place in conjunction with the European Microwave Week (EuMW), the most important microwave event in Europe. In 2012, EuMW was held at the RAI Center in Amsterdam between October 28 and November 2. The meeting gathered about 45 participants, and 18 Chapters from Region 8 were represented.

A Building Element of an Active Negative Permeability Metamaterial

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents an active particle designed as a building block of an active volumetric metamaterial showing negative magnetic polarizability. The particle is composed of a conducting ring loaded by an impedance with a negative real part. This impedance is produced by a one-port transistor circuit. Measurements of the fabricated element verified its working principle in the RF range.

A Dual Band Leaky Wave Antenna on a CRLH Substrate Integrated Waveguide

  • DOI: 10.1109/TAP.2013.2256097
  • Odkaz: https://doi.org/10.1109/TAP.2013.2256097
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the results of an investigation of a new version of a leaky wave antenna designed on a CRLH substrate integrated waveguide. The antenna operates in two frequency bands and its main beam can be steered from backward to forward direction by changing the frequency. The antenna structure is planar and can be fabricated by a standard PCB technology, so it is suitable for mass production. An efficient method for determining the complex dispersion characteristic of periodic 1D structure is proposed.

A Planar Leaky Wave Antenna Operating in Two Frequency Bands

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The investigation and design of a leaky wave antenna is presented in this paper. The antenna has a planar structure composed of a substrate integrated waveguide. This waveguide is designed as a composite right/left-handed transmission line operating in two balanced frequency bands spanned from approx. 8.6 up to 9.5 GHz and from 15 up to 19 GHz with closed gaps between the left- and right-handed regions. The novelty of the structure lies in its dual band operation and the applied SIW technology. An effective way of determining the complex dispersion characteristics of the antenna is presented, and an equivalent circuit of a line unit cell is derived. The antenna was fabricated and the measured characteristics are in good agreement with those predicted by the simulation. The advantage of the antenna lies in its planar structure, which is suitable for cheap mass production.

A Uniplanar Inductively Loaded Scatterer of Reduced Size for Chipless RFID Tags

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The aim of this work is to investigate a uniplanar scatterer for RFID chipless tags able to store an increased amount of information per unit surface. This scatterer is a modification of the U-folded dipole – a quarter wavelength resonator - that is shortened by a meander inductor inserted at the position of the short or by an interdigital capacitor connected at the open end. The proposed uniplanar structure is suitable for cheap mass production.

Leaky Wave Antennas Designed on a Substrate Integrated Waveguide

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the results of an investigation of leaky wave antennas designed on a substrate integrated waveguide. The antennas are of the following types: antenna radiating from a slot in the top waveguide wall, CRLH and dual band CRLH leaky wave antennas. The substrate integrated waveguide can easily be integrated with planar microwave circuits. Antennas designed on this transmission line have a planar structure, and can be fabricated by a standard PCB technology, so they are suitable for mass production.

Loss compensation in RF metamaterials by single transistor circuits

  • DOI: 10.1109/MetaMaterials.2013.6809005
  • Odkaz: https://doi.org/10.1109/MetaMaterials.2013.6809005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper shows that reduction of losses, or even addition of gain, in RF metamaterials can be achieved by a single transistor circuit that exploits its conditional stability. The presented solution offers not only extreme simplicity, but also absolute control over stability and achieved gain values.

Novel Size-Reduced Unit Cells for Uniplanar Chipless RFID Tags

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper introduces the two new size-reduced unit cells/scatterers in the form of uniplanar resonators for application in frequency spectrum-based uniplanar chipless RFID tags. They are derived from U-folded dipole loaded by either meander line inductor or interdigital capacitor. Radar cross section, and resonant frequency has been evaluated by EM simulation and S-parameters have been measured and calculated when scatterers have been placed in parallel-plate waveguide. The results clearly show the trade-off between size-reduction and radar cross section proportional to read range of the proposed configurations. Their potential lies in the development of new smaller uniplanar chipless tags with higher information density.

A Dual Band SIW Leaky Wave Antenna

  • DOI: 10.1109/MWSYM.2012.6258337
  • Odkaz: https://doi.org/10.1109/MWSYM.2012.6258337
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the results of an investigation of a new version of a leaky wave antenna that is based on a CRLH substrate integrated waveguide (SIW). The antenna is designed so that it can radiate in two frequency bands. The direction of the main lobe of the antenna radiation pattern can be steered by changing the frequency in both bands from backward direction to forward direction. The measured characteristics are in good agreement with those predicted by the simulation. The SIW structure based on standard PCB technology makes the antenna suitable for integration directly into T/R circuits or antenna arrays.

A Metamaterial with an Isotropic Response

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of the 14th International Conference on Mathematical Methods in Electromagnetics Theory. Piscataway: IEEE, 2012. pp. 403-408. ISBN 978-1-4673-4479-1.
  • Rok: 2012
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The behavior and the excitation of negative polarizabilities by planar resonators are explained using simple analytical models. Particular single negative resonators showing negative electric or negative magnetic polarizability are introduced, namely: an electric dipole terminated by an inductor, a split ring resonator and a double H-shaped resonator. Several geometries of these resonators are studied. The two planar resonators are located on the two surfaces of a dielectric substrate to get an element with a double negative response. These resonant particles respond strongly anisotropically. A proper spatial arrangement of these particles with 3D periodicity can make the response isotropic. The planar resonators are simple to fabricate using technology for standard printed circuit boards. They are therefore cheap, and suitable for mass production. Measurements have confirmed the design considerations and the simulation results.

An Improved Technique for Estimating Wall Parameters from Time-Delay Through-Wall Radar Measurements

  • Autoři: Protiva, P., Mrkvica, Jan, Šafařík, M., Šikl, R., Vlasák, V., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of 22nd International Conference Radioelektronika 2012. Brno: VUT v Brně, FEKT, Ústav radioelektroniky, 2012. p. 107-110. ISBN 978-80-214-4468-3.
  • Rok: 2012
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, we propose an improved walll parameter estimation algorithm that can provide the unknown wall thickness and permittivity using time-delay-only through-wall radar measurements. The algorithm is based on measuring the time difference between echoes backscattered from the front and rear surface of the wall at different Tx-Rx antenna separations. The performance of our improved method is verified by an experiment with two real walls, and the measurement results show that even measuring the reflected signals only at two different antenna separations is now sufficient for estimating the unknown wall parameters.

Analysis of a CRLH SIW Dual Band Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the results of an investigation of a new version of a CRLH substrate integrated waveguide leaky wave antenna. The antenna operates in two frequency bands and its main beam can be scanned by changing frequency from backward to forward. The antenna structure is planar and can be fabricated by a standard PCB technology, so it is suitable for mass production.

Detection of Spiral Resonator Array for Chipless RFID

  • DOI: 10.1109/EuCAP.2012.6206202
  • Odkaz: https://doi.org/10.1109/EuCAP.2012.6206202
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Presented paper analyzes the influence of different configurations of the planar resonator arrays of the size 16×4 up to 16×16 elements on the reflection coefficient of the halfwavelength dipole probe in the frequency range 600-1000 MHz. Four different square spiral resonators of the outer diameter 7 mm (~ 0.02λ0@800 MHz) with various total lengths of the conductor are used as array building elements. It is shown that specific arrangement of the resonators in the array enhances the response of the probe. The work was motivated by the potencial application of such arrays in chipless RFID technology.

Planar Resonators for Metamaterials

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the results of an investigation into a combination of electric and magnetic planar resonators in order to design the building element of a volumetric metamaterial showing simultaneously negative electric and magnetic polarizabilities under irradiation by an electromagnetic wave. Two combinations of particular planar resonators are taken into consideration. These planar resonators are an electric dipole, a split ring resonator and a double H-shaped resonator. The response of the single resonant particle composed of a resonator with an electric response and a resonator with a magnetic response is strongly anisotropic. Proper spatial arrangement of these particles can make the response isotropic. This is obtained by proper placement of six planar resonators on the surface of a cube that now represents a metamaterial unit cell. The cells are distributed in space with 3D periodicity.

Region 8 MTTS Chapter Chairs Meeting in Manchester

  • Autoři: prof. Ing. Jan Macháč, DrSc., Pasquet, D., Szendrenyi, B.
  • Publikace: IEEE Microwave Magazine for the Microwave and Wireless Engineer. 2012, 13(2), 91-92. ISSN 1527-3342.
  • Rok: 2012
  • DOI: 10.1109/MMM.2011.2181629
  • Odkaz: https://doi.org/10.1109/MMM.2011.2181629
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The annual meeting of the chairs and other Chapter representatives takes place in conjuction with European Microwave Week (EuMW), the most important microwave event in Europe. In 2011, EuMW was held in Manchester, United Kingdom, at Manchester Central 9-14 October. The Chapter chairs´ meeting (CCM) took place at Manchester Central on 10 October.

Unit Cell of Metamaterial with Isotropic Response Made of Planar Resonators

  • Autoři: Bláha, M., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of the 42nd European Microwave Conference. London: Horizon House Publications, 2012. pp. 679-682. ISBN 978-2-87487-027-9.
  • Rok: 2012
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents results of investigation of the resonant particle intended to be used in design of metamaterial with negative refraction index that shows the isotropic response to irradiating wave. The particle has planar structure, therefore it can be simply fabricated by a standard PCB technology. The resonant planar particle is composed of two double H-shaped resonators. The first resonator uses the response to electric field producing negative electric polarizability at its first resonance, whereas the second resonator works at its second resonance producing negative magnetic polarizablity. A cube bearing six resonators on its faces represents the unit cell of double negative metamaterial with isotropic response.

A Dual Band CRLH Substrate Integrated Waveguide

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the application of a substrate integrated waveguide (SIW) for the design of a leaky wave antenna radiating simultaneously in two independent frequency bands. The antenna is based on a compensated right-left handed SIW transmission line. Due to this, the direction of the main lobe of the antenna radiation pattern can be steered by changing the frequency from backward to forward direction. The structure novelty is in a dual band operation. The characteristics and radiation aspects of the antenna are discussed. The measured antenna characteristics are in good agreement with those predicted by the simulation. Due to the SIW technology, the antenna is suitable for integration into T/R circuits and antenna arrays.

An FET-Based Unit Cell for an Active Magnetic Metamaterial

  • DOI: 10.1109/LAWP.2011.2167311
  • Odkaz: https://doi.org/10.1109/LAWP.2011.2167311
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A particle that can be used to create an active magnetic metamaterial has been designed using an FET transistor loaded in its gate by a conducting ring and in its source by a parallel resonance circuit. The design procedure is discussed, and the working principle is experimentally demonstrated in the RF range.

Artificial Electromagnetic Structures for High Frequency Technology

  • Autoři: Bečvář, V., Bláha, M., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Workshop 2011. Praha: České vysoké učení technické v Praze, 2011. pp. 1-4.
  • Rok: 2011
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the results of an investigation into a combination of electric and magnetic planar resonators in order to design the building element of a volumetric metamaterial showing simultaneously negative electric polarizability and magnetic polarizability under irradiation by an electromagnetic wave. The magnetic element is a split ring resonator, and the electric element is an electric dipole terminated by an inductor. The response of the single resonant particle is strongly anisotropic. Proper spatial arrangement of these particles can make the response isotropic. The possibility of obtaining a non-bianisotropic response is taken into account.

Building Elements of a Volumetric Metamaterial

  • Autoři: Bečvář, V., Bláha, M., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of the 2011 IEEE MTTS - International Microwave Symposium. Piscataway: IEEE, 2011. pp. 1-4. ISSN 0149-645X. ISBN 978-1-61284-756-6.
  • Rok: 2011
  • DOI: 10.1109/MWSYM.2011.5972587
  • Odkaz: https://doi.org/10.1109/MWSYM.2011.5972587
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the results of an investigation into a combination of electric and magnetic planar resonators in order to design the building element of a volumetric metamaterial showing simultaneously negative electric polarizability and magnetic polarizability under irradiation by an electromagnetic wave. The magnetic element is a split ring resonator, and the electric element is an electric dipole terminated by an inductor. The response of the single resonant particle is strongly anisotropic. Proper spatial arrangement of these particles can make the response isotropic. The possibility of obtaining a non-bianisotropic response is taken into account.

Estimation of Wall Parameters From Time-Delay-Only Through-Wall Radar Measurements

  • Autoři: Protiva, P., Mrkvica, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: IEEE Transactions on Antennas and Propagation. 2011, 56(11), 4268-4278. ISSN 0018-926X.
  • Rok: 2011
  • DOI: 10.1109/TAP.2011.2164206
  • Odkaz: https://doi.org/10.1109/TAP.2011.2164206
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Knowledge of the basic characteristics of the wall is important for the proper function of through-wall radars (TWR). In this paper, we introduce an estimation method that can provide the unknown wall parameters in real time. Our algorithm is based on a modified version of common midpoint processing, a technique adopted from geophysics. Using this method, it is possible to estimate both the thickness and the permittivity of the wall from time-delay-only measurements performed at several different transceiver-receiver separations. Time-delay estimation of echoes backscattered from the wall at each antenna separation is performed by a subspace super-resolution method. The performance of our estimation algorithm is verified by simulations, and we also present the results for two real brick walls measured using the time-domain technique. The estimated wall parameters can be utilized for improving the accuracy of real-time locating and tracking of moving humans by TWR.

Free Space Polarizability Measurement Method

  • Autoři: doc. Ing. Lukáš Jelínek, Ph.D., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of Metamaterials´ 2011: The Fifth International Congress on Advanced Electromagnetic Materials in Microwaves and Optics. Louvain-la-Neuve: UCL, Laboratoire d´Hyperfréquences, 2011. pp. 967-969. ISBN 978-952-67611-0-7.
  • Rok: 2011
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A simple and precise method for free space polarizability measurement of electrically small particles is presented. The method is based on a measurement of the scattering parameters of a waveguide loaded by a particle, and on knowledge of the dipolar polarizabilities of two calibration standards.

Full-wave Analysis of Two Parallel Slotlines on a Common Substrate

  • Autoři: Kotlan, V., prof. Ing. Jan Macháč, DrSc., Mesa, F., Rodriguer-Berral, Raul
  • Publikace: PIERS 2011 Suzhou Proceedings. Cambridge, MA: The Electromagnetics Academy, 2011. pp. 827. ISSN 1559-9450. ISBN 978-1-934142-18-9.
  • Rok: 2011
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents a detailed parametric study of the two coupled slotlines located on one substrate. The wave propagating on the active slotline together with the wave propagating along the passive slotline are compared with the wave that propagates along a single slotline. In addition, the analysis of the crosstalk in the two parallel slotlines on the common substrate is verified experimentally. The measured field distributions the calculated field distributions quite well.

Microwave Noise Field Behaves Like white Light

  • Autoři: Polívka, J., Fiala, P., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Progress In Electromagnetics Research. 2011, 111 311-330. ISSN 1559-8985.
  • Rok: 2011
  • DOI: 10.2528/PIER10041304
  • Odkaz: https://doi.org/10.2528/PIER10041304
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents various applications where wide-band signals are the dominant factor. The approaches applied here are based on the present knowledge in the field of white light theory (the THz band), the particle theory of light, and the wave theory of light. White light theory is used to investigate wide-band applications of non-coherent electromagnetic waves in the GHz range represented by noise. In addition, the theoretical approaches to the field of white light are confirmed by various experiments with noise Felds applied in the GHz range. These experiments show clear advantages of measurements performed by means of noise fields. The most important feature of these fields is the absence of interference effects.

Planar Resonator with Negative Electric and Magnetic Polarizabilities

  • Autoři: Bečvář, V., Bláha, M., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of 21st International Conference Radioelektronika 2011. Brno: VUT v Brně, FEKT, Ústav radioelektroniky, 2011. p. 173-176. ISBN 978-1-61284-322-3.
  • Rok: 2011
  • DOI: 10.1109/RADIOELEK.2011.5936389
  • Odkaz: https://doi.org/10.1109/RADIOELEK.2011.5936389
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents an originally designed planar resonator that shows at the same time negative electric polarizability and magnetic polarizability. The resonator is composed as a combination of electric and magnetic planar resonators. Consequently it is a useful building block for a double negative volumetric metamaterial. The magnetic element is a split ring resonator, and the electric element is an electric dipole terminated by an inductor. The response of the single resonator is strongly anisotropic. A proper spatial arrangement of these resonators can make the response isotropic. The design process has been verified experimentally.

Substrate Integrated Waveguide at Antenna Applications

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of Advanced Methods in the Theory of Electrical Engineering (AMTEE´11). Plzeň: Západočeská univerzita v Plzni, 2011. pp. III-15-III-16. ISBN 978-80-7043-993-7.
  • Rok: 2011
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents the substrate integrated waveguide applied as a basis of leaky wave antennas. The substrate integrated waveguide structures are extremely useful for integrating the antenna into any system or antenna array. The standard PCB process is applied to fabricate these antennas. The two antenna structures are presented. The first antenna radiates through the longitudinal slot in the surface integrated waveguide top wall. The second antenna is based on the compensated right-left handed line. It radiates through meander slots representing series line capacitances. This is a dual band antenna radiating simultaneously in two independent frequency bands. The characteristics and radiation aspects of the antennas are discussed. The measured characteristics of the two antennas are in good agreement with those predicted by the simulation.

Time Delay Estimation of UWB Radar Signals Backscattered from a Wall

  • Autoři: Protiva, P., Mrkvica, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Microwave and Optical Technology Letters. 2011, 53(6), 1444-1450. ISSN 0895-2477.
  • Rok: 2011
  • DOI: 10.1002/mop
  • Odkaz: https://doi.org/10.1002/mop
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Estimating the basic characteristics of a wall is especially important in the field of through-wall radar imaging. In this article, we focus on the time delay estimation of signals measured by an ultra-wideband short-pulse radar. We describe the essential signal preprocessing steps, which are applied before a subspace superresolution method is used to estimate the time delays of overlapping pulses backscattered from the wall. The signal correlation matrix is estimated using only one snapshot of the measured data, and the algorithm can operate in real time. In addition, to resolve closely spaced correlated echoes, we apply an improved spatial smoothing method. The performance of our algorithm is verified by simulations, and we also present the measurement results for two real brick walls.

A Compact Step Recovery Diode Subnanosecond Pulse Generator

  • Autoři: Protiva, P., Mrkvica, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Microwave and Optical Technology Letters. 2010, 52(2), 438-440. ISSN 0895-2477.
  • Rok: 2010
  • DOI: 10.1002/mop.24945
  • Odkaz: https://doi.org/10.1002/mop.24945
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A Compact Ultra-Wideband subnanosecond pulse generator is described in this article. The fundamental part of the generator consists of a step recovery diode (SRD), which works as a waveform edge sharpener. The SRD is included in a compact pulse-forming network, which is used to form a narrow Gaussian pulse. The proposed circuit solution utilizes the performance of the SRD effectively with minimal requirements regarding the driver stage of the generator. The measurements show the waveform and power spectrum of the Caussian pulse that is generated.

A Resonant Particle for a Volumetric DNG Metamaterial

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper studies a combination of electric and magnetic particles in order to obtain simultaneously negative electric and magnetic polarisability under irradiation by an electromagnetic wave. The magnetic particle is represented by a split ring resonator, and electric particle is represented by an electric dipole terminated by an inductor. They are combined together in a way that obtains a resonant element with inversion symmetry. The internal coupling between these resonators located in a waveguide is subjected to a special study. The response of this particle is strongly anisotropic, but an isotropic response can be achieved by a proper spatial arrangement.

A Substrate Integrated Waveguide Leaky Wave Antenna Radiating from a Slot in the Broad Wall

  • Autoři: prof. Ing. Jan Macháč, DrSc., Lorenz, P., Saglam, M., Bui, C.T., Kraemer, W.
  • Publikace: Proceedings - IEEE MTT-S International Microwave Symposium. Piscataway: IEEE, 2010. p. 5-8. ISSN 0149-645X. ISBN 978-1-4244-6057-1.
  • Rok: 2010
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the application of a substrate integrated waveguide (SIW) for the design of a leaky wave antenna radiating from a slot in the broad wall. The antenna radiates into a beam split into two amin lobes and its gain is about 7 dB až 19 GHz. The characteristics and radiation aspects of the antenna are discussed here. The measured antenna characteristics are in good agreement with those predicted by the simulation. Due to the SIW technology, the antenna is suitable for integration into T/X circuits and antenna arrays.

Crosstalk in Parallel Slotlines

  • Autoři: Kotlan, V., prof. Ing. Jan Macháč, DrSc., Mesa, F., Rodriguez-Berral, R.
  • Publikace: 2010 Asia-Pacific Microwave Conference Proceedings. Tokyo: IEICE, Institute of Electronics, Information and Communication Engineers, 2010. pp. 1605-1608. ISBN 978-4-902339-22-2.
  • Rok: 2010
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper deals with high-frequency crosstalk effects between two slotlines located in parallel on the same substrate. The analysis consists of a full wave integral equation formulation solved in the spectral domain using the method of moments, and accounts for both leaky modes and the residual wave excited on the structure. The numerical results thus obtained show how an electric field is induced in the passive slot line due to coupling with an adjacent slot line excited by a current source. Comparisons with measured data and with the results provided by a commercial simulator are also provided.

Experimental Verification of UWB Pulse Propagation in Indoor and Outdoor Environments

  • Autoři: Protiva, P., Mrkvica, J., Dvořák, D., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of 15th Conference on Microwave Techniques COMITE 2010. Brno: VUT v Brně, FEKT, Ústav radioelektroniky, 2010. pp. 153-156. ISBN 978-1-4244-6351-0.
  • Rok: 2010
  • DOI: 10.1109/COMITE.2010.5481256
  • Odkaz: https://doi.org/10.1109/COMITE.2010.5481256
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, we present measurement results of ultra-wideband propagation in selected indoor and outdoor environments, including forest and dense scrub. The measurement setup and procedure is described. The measurements have been performed using a time-domain measurement system consisting of a pulse generator and a sampling oscilloscope. Then, post-processing of the recorded data is described. First, we apply the CLEAN algorithm in order to study and compare the multipath nature of the investigated propagation channels. Then we present the power gain profiles.

Fishnet Metamaterials - Rules for Refraction and Limits of Homogenization

  • DOI: 10.1364/OE.18.017940
  • Odkaz: https://doi.org/10.1364/OE.18.017940
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The perfectly conducting stacked fishnet metamaterial is studied in this paper. The analysis is based on a combination of the mode matching method together with the generalized eigenvalue problem, and takes into account wave propagation along all three Cartesian axes. The analysis has been developed for a fishnet of square lateral periodicity and for two particular polarizations, namely TE and TM, corresponding to the two most common excitations. The 1D and 2D dispersion characteristics are calculated for both polarizations, showing that the TM waves undergo negative refraction in a narrow frequency band just below Wood's anomaly, whereas TE polarized waves exhibit ordinary positive refraction. Finally, possible homogenization of the fishnet metamaterial is considered, showing that only for small angles of incidence and in the immediate vicinity of Wood's anomaly can the fishnet be seen as homogenizable uniaxial medium.

High-frequency Crosstalk between two Parallel Slotlines

  • Autoři: Kotlan, V., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: IET Microwaves, Antennas & Propagation. 2010, 4(12), 2240-2246. ISSN 1751-8725.
  • Rok: 2010
  • DOI: 10.1049/iet-map.2009-0448
  • Odkaz: https://doi.org/10.1049/iet-map.2009-0448
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A study of high-frequency crosstalk between tvo slotlines located in parallel on the same substrate is presented. The electric field is induced in a passive slotline because of coupling from the other closely placed slotline excited by a source. A full-wave analysis, the method of moments in the spectral domain, taking into account both the bound and the residual and leaky modes, is used to examine high-frequency crosstalk. As a result, the voltage of the total wave propagating along the coupled lines is calculated. The theory is verified by measurement and by a simulation performed in CST microwave studio.

Homogenization of Fishnet Metamaterials: Possibilities and Restrictions

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The possibilities and restrictions of homogenization in fishnet metamaterials are studied. By means of 1D and 2D dispersion diagrams obtained by combination of mode-matching with generalized eigenvalue problem it is shown that in narrow frequency region just below Wood's anomaly the approximation of fishnet by uniaxial medium is allowed. It is also shown that this is the frequency band of possible negative refraction.

Limitations in Measurement of Leaky Waves on Open Planar Transmission Lines

  • Autoři: Kotlan, V., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of 15th Conference on Microwave Techniques COMITE 2010. Brno: VUT v Brně, FEKT, Ústav radioelektroniky, 2010. pp. 167-169. ISBN 978-1-4244-6351-0.
  • Rok: 2010
  • DOI: 10.1109/COMITE.2010.5481258
  • Odkaz: https://doi.org/10.1109/COMITE.2010.5481258
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper documents leakage on a slotline through simulations done in the CST Microwave Studio. Paper shows the difference between fields of infinite dimensions and finite dimensions of the slotline and then the results of measurement of the electric field. The slotline is designed to radiate power into its substrate in the form of leaky waves in a defined frequency range. The field distribution on a fabricated slotline of finite dimensions was measured in the same way as in the case of the microstrip line that was successfully measured in our previous work. The electric field measured above the slotline substrate with the aim of experimental verification of leaky waves is figured out using 3D visualization here. The main aim of the paper is to show that measurement over the substrate is not in general a proper way to verify leaky modes in all types of open planar transmission lines.

Numerical and Experimental Study of the Voltage Excited Along a Slotline by a Current Source

  • DOI: 10.1029/2009RS004139
  • Odkaz: https://doi.org/10.1029/2009RS004139
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents an analysis of a slotline excited by a current source connected across the slot. The method of moments applied in the spectral domain is used. As a result, the voltage of a wave composed of bound and leaky modes as well as residual waves is calculated along the slot. Interesting behavior of the voltage wave in the neighborhood of the source is shown. Both numerical and measured results are given.

Ultra-wideband Pulse Waveform Generation Based on Combining Subnanosecond Gaussian Pulses

  • Autoři: Protiva, P., Mrkvica, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Microwave and Optical Technology Letters. 2010, 52(11), 2401-2405. ISSN 0895-2477.
  • Rok: 2010
  • DOI: 10.1002/mop.25498
  • Odkaz: https://doi.org/10.1002/mop.25498
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A technique for generating ultra-wideband pulse waveforms is described in this article.It consists in combining subnanosecond Gaussian pulses from multiple sources. This method enables us to form complex pulse waveforms without the need to use transmission line pulse forming networks and delay lines. Two designs for an experimental generator utilizing the pulse combining principle are presented. The first generator is composed of two positive Gaussian pulsers and one negative Gaussian pulser. Analog time shifters were used to control the timing of each pulser. The circuit can be used as the generator of a Gaussian doublet. The second generator is composed of four identical Gaussian pulsers. Programmable ECL logic delay chips were employed to adjust the timing in this case. The measurements demonstrate the wide capability of the pulse combining scheme for controlling the spectral properties of the pulse waveform that is generated.

A Double H-shaped Resonator and its use as an Isotropic ENG Metamaterial

  • Autoři: Bláha, M., prof. Ing. Jan Macháč, DrSc., Rytíř, M.
  • Publikace: International Journal of Microwave and Wireless Technologies. 2009, 2009(1), 323-329. ISSN 1759-0787.
  • Rok: 2009
  • DOI: 10.1017/S1759078709990420
  • Odkaz: https://doi.org/10.1017/S1759078709990420
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a new planar particle that shows negative effective permittivity under irradiation by an electromagnetic wave. The mutual coupling between the couples of these particles is studied in particular. The response of this particle sensitive to an electric field is strongly anisotropic. The particle is aimed to be used to compose an isotropic epsilon-negative metamaterial in two forms. First, a unit cell of the metamaterial consists of a cube bearing six particles on its faces, located with specific orientations. The experiments showed that this unit cell is suitable for manufacturing an isotropic epsilon-negative metamaterial obtained by arranging these cells in a 3D cubic periodic system. The second form of an epsilon-negative metamaterial with an isotropic response consists of the planar particles themselves, distributed quasi-randomly, composing a 2D system and/or of particles placed in spherical shells and distributed fully randomly in a hosting material forming a 3D

Adaptive Symbol Length for OFDM Systems in Doubly Selective Channels

  • Autoři: Ali Ramadan, A., Alsaih, A., Khanzada, T.J., prof. Ing. Jan Macháč, DrSc., Abbas, O.
  • Publikace: Proceedings of the 2009 Asia Pacific Microwave Conference. Singapore: IEEE Singapore, 2009. pp. 1541-1544. ISBN 978-1-4244-2801-4.
  • Rok: 2009
  • DOI: 10.1109/APMC.2009.5384417
  • Odkaz: https://doi.org/10.1109/APMC.2009.5384417
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Symbol length is an important factor that can affect the spectrum efficiency and the performance of Orthogonal Frequency Division Multiplexing OFDM system. However, the symbol length is usually fixed in conventional OFDM systems, which decreases the spectrum efficiency considerably, especially in a mobile environment. This paper introduces an adaptive OFDM system in which the delay spread and Doppler spread are estimated at the receiver and according to their estimated values, the transmitter vary the symbol length such that the Bit Error Rate BER is always around a certain predetermined value. The value of the BER is chosen according to the type of the transmitted information. Simulation has been implemented and the results show that the proposed adaptive algorithm gives an improvement in the total throughput of the system without significantly sacrificing the BER performance.

Comparative Analysis of the Dispersion Characteristics of a Slotline and a Microstrip Line

  • Autoři: Kotlan, V., prof. Ing. Jan Macháč, DrSc., Mesa, F.
  • Publikace: Proceedings of the 2009 Asia Pacific Microwave Conference. Singapore: IEEE Singapore, 2009. ISBN 978-1-4244-2801-4.
  • Rok: 2009
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper compares the dispersion characteristic of a slotline with that of a microstrip line. A full wave analysis of a slotline including the excitation source is presented. All kinds of modes are taken into account, including a bound mode, leaky modes, and a residual wave. The line is excited by a timeharmonic source of constant current connected across the slot of the line. The theoretically predicted results have been verified by experiments and by simulations in the CST Microwave Studio. A continuous behaviour is documented, rather than the step-like behaviour of waves propagating along the investigated lines as predicted by a pure eigenmode analysis.

Experimental Verification of Leaky Waves on a Microstrip Line

  • Autoři: Houška, M., Kotlan, V., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: 19th International Conference Radioelektronika 2009 - Proceedings. Bratislava: FEI, Slovak University of Technology, 2009. pp. 157-159. ISBN 978-80-214-3865-1.
  • Rok: 2009
  • DOI: 10.1109/RADIOELEK.2009.5158786
  • Odkaz: https://doi.org/10.1109/RADIOELEK.2009.5158786
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    It is well known that leaky waves can be found in addition to the bound wave on planar transmission lines at proper frequency ranges. This effect is documented here under the real conditions of a microstrip line of finite dimensions excited by a real source supplying finite power. The presence of these modes depends on the dimensions of the microstrip and on the frequency of the source. This paper describes an experimental verification that illustrates the existence of leaky waves on the microstrip line.

High Power Monocycle Pulse Generator for Through-the-Wall Radar Transmitter

  • Autoři: Protiva, P., Mrkvica, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of the 2009 Asia Pacific Microwave Conference. Singapore: IEEE Singapore, 2009. p. 2324-2327. ISBN 978-1-4244-2801-4.
  • Rok: 2009
  • DOI: 10.1109/APMC.2009.5385448
  • Odkaz: https://doi.org/10.1109/APMC.2009.5385448
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a sub-nanosecond pulse transmitter of through-the-wall surveillance radar. The basis of the generator is a step recovery diode and a unique pulseforming circuit, which forms an ultra-wideband Gaussian pulse. High amplitude pulses are advantageous for obtaining a good radar range, especially when penetrating thick and lossy building walls. In order to increase the output power of the transmitter, the outputs of two identical pulse generators were connected in parallel. A transmission line pulse forming network was then used to form an output monocycle pulse. The measurements show waveforms of the generated monocycle pulses over 33 V in amplitude.

Realization of a Microstrip Triple-Mode Bandpass Filter Using a Square-Loop Resonator

  • Autoři: Balalem, A., Ali, A.R., Amari, S., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: 2009 IEEE MTT-S International Microwave Symposium Digest. Boston: IEEE, 2009. p. 849-851. Causal Productions Pty Ltd. PO BOX 100, Rundle Mall, SA 5000, Australia. ISSN 0149-645X. ISBN 978-1-4244-2803-8.
  • Rok: 2009
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper introduces a microstrip triple-mode resonator that is realized by adding an additional path to the microstrip square-loop dual-mode resonator. The additional path is realized by a meander half wavelength strip that is connected to two opposite corners of the square-loop resonator. A third order pseudo-elliptic bandpass filter utilizing this resonator is presented. Good agreement is achieved between the theoretical, simulated and measured results.

Slotline Operating within a Wide Frequency Band: Excitation of Waves by a Real Source

  • Autoři: Kotlan, V., prof. Ing. Jan Macháč, DrSc., Mesa, F.
  • Publikace: 2009 IEEE MTT-S International Microwave Symposium Digest. Boston: IEEE, 2009. pp. 137-140. Causal Productions Pty Ltd. PO BOX 100, Rundle Mall, SA 5000, Australia. ISSN 0149-645X. ISBN 978-1-4244-2803-8.
  • Rok: 2009
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a full wave analysis of a slotline including the excitation source. All kinds of modes are taken into account, including a bound mode, leaky modes, and a residual wave. The line is excited by the source of constant current connected across the line slot. The paper specifies more correctly or improve some of our views about waves transmission along the slotline obtained by an eigen mode analysis. This considers namely slotline applications and wide frequency band. The theoretically predicted results are verified by experiments and by simulations in CST Microwave Studio.

Sub-nanosecond Pulse Generator for Through-the-Wall Radar Application

  • Autoři: Protiva, P., Mrkvica, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: European Microwave Week 2009 - Conference Proceedings. London: Horizon House Publications, 2009. p. 230-234. ISBN 978-1-4244-4748-0.
  • Rok: 2009
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a sub-nanosecond pulse generator intended for a transmitter of through-the-wall radar. The basis of the generator is a step recovery diode, which is used to sharpen the slow rise time edge of an input driving waveform. A unique pulse shaping technique is then applied to form a Gaussian pulse. A simple transistor switching circuit was used to drive this pulser, which transforms a trigger signal to a driving pulse with the timing and amplitude parameters required by the step recovery diode. The maximum pulse repetition frequency of the generator is 20 MHz. High amplitude pulses are advantageous for obtaining a good radar range, especially when penetrating thick lossy walls. In order to increase the output power of the transmitter, the outputs of two identical generators were connected in parallel. The measurement results are presented, which show waveforms of the generated Gaussian pulses approximately 180 ps in width and over 32 V in amplitude.

UWB Bandpass Filter with Wide Stopband Using Lumped Coupling Capacitors

  • Autoři: Abdel-Rahman, A., Balalem, A., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: Proceedings of the 2009 Asia Pacific Microwave Conference. Singapore: IEEE Singapore, 2009. pp. 949-952. ISBN 978-1-4244-2801-4.
  • Rok: 2009
  • DOI: 10.1109/APMC.2009.5384328
  • Odkaz: https://doi.org/10.1109/APMC.2009.5384328
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper introduces an improved performance ultra-wideband bandpass filter by using lumped capacitors as an external coupling to stepped impedance DGS lowpass filter structure. The filter has a passband from 3.1 to 10.6 GHz and a wide stopband up to more than 20 GHz. Insertion loss less than 0.6 dB. The filter has a length of just 13 mm. The experimental results agree well with the predicted ones.

A Double H-Shaped Resonator for an Isotropic ENG Metamaterial

  • Autoři: prof. Ing. Jan Macháč, DrSc., Rytíř, M., Protiva, P., Zehentner, J.
  • Publikace: European Microwave Week 2008 "Bridging Gaps" Conference Proceedings. London: Horizon House Publications, 2008. p. 547-550. ISBN 978-1-4244-3794-8.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a new planar particle showing negative effective permittivity. The response of this particle, aimed to be sensitive to an electric field, is strongly anisotropic. The particle is used to design an isotropic epsilon-negative metamaterial in two forms. Firstly, a unit cell of the metamaterial consists of a cube bearing six proposed particles on its faces, located with specific orientations. The experiments showed that this unit cell is suitable for manufacturing an isotropic epsilon-negative metamaterial obtained by arranging these cells in a 3D cubic periodic system. The second form of an epsilon negative metamaterial with an isotropic response consists of the proposed planar particles themselves, distributed quasi-randomly, composing a 2D system and/or of particles placed in spherical shells and distributed fully randomly in a hosting material composing a 3D system. The isotropy of these systems was verified by measurements in a rectangular waveguide.

A New Transformation of Bandpass Filter to Bandstop Filter Using Multilayer-Technique and U-Defected Ground Structure (DGS)

  • Autoři: Boutejdar, A., Batmanov, A., prof. Ing. Jan Macháč, DrSc., Burte, E., Omar, A.
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. p. 179-182. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A novel compact microstrip bandpass/Bandstop filters realized by combining new Multilayer Method with electrically coupled microstrip U-shaped DGS resonators, is proposed. The proposed filters have low insertion loss and are compact in size due to the slow-wave effect. They also have sharp transition regions due to the presence of two transmission zeros on both sides of their passband. The measured center frequency, bandwidth and insertion loss are 3.4 GHz, 40%, and 0.5 dB respectively. The simulated and measured results show good agreement and validate the proposed approach.

A Planar Version of a Slotline Leaky Wave Antenna with a Stacked Substrate

  • Autoři: prof. Ing. Jan Macháč, DrSc., Pavliš, A., Houška, M., Zehentner, J.
  • Publikace: 17th International Conference on Microwaves, Radar and Wireless Communications. Warsaw: IEEE, 2008. pp. 746-749. ISBN 978-1-4244-3122-9.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a new version of a leaky wave antenna based on a conductorbacked slotline with a stacked substrate. The advantage of this new structure is its flat top surface, due to the antenna being fed from the rear side via an SMA connector. The antenna radiates into a single main beam above the substrate. A bi-directional antenna radiating symmetrically both forwards and backwards was obtained by mirroring the structure.

A Simple Ultra-Wideband Suspended Stripline Bandpass Filter with Very Wide Stop-Band

  • Autoři: Balalem, A., Menzel, W., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: IEEE Microwave and Wireless Components Letters. 2008, 18(3), 170-172. ISSN 1531-1309.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper introduces a simple ultra-wideband suspended stripline filter with a pass-band from 3.1 to 10.6 GHz and a very wide stop-band up to more than 25 GHz. The filter is realized by capactive coupling of a quasi-lumped low-pass filter to the I/O ports. Insertion loss in the pass-band is better than 0.5 dB. The filter has a length of 13.8 mm. Excellent agreement is achieved between measured and simulated results.

Adaptive Pilot Distribution for OFDM Systems in Time-Variant Channels

  • Autoři: Ali, R.A., Balalem, A., Khanzada, T., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: Asia Pacifik Microwave Conference 2008 - Proceedings. Hong Kong: University of Hong Kong, 2008. p. 255-258. ISBN 978-1-4244-2641-6.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    OFDM is sensitive to frequency offsets and phase noise. In order to estimate the channel, training symbols (pilots) are inserted among the transmitted data. The pilot spacing in time and frequency must be designed according to the coherence time and coherence bandwidth of the channel. In this paper an adaptive method for pilot distribution according to the variation level of the channel is described. It is shown that the adaptive method increases the total capacity of the system.

Branch Line Coupler on an Artificial Dielectric Substrate

  • Autoři: prof. Ing. Jan Macháč, DrSc., Fabian, J., Protiva, P.
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. p. 301-304. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a possible application of an artificial dielectric substrate. The substrate is fabricated as a 2D array of metallic posts separated from the top conductor by a thin dielectric slab. The effective permittivity of a microstrip line fabricated on this substrate depends on the dimensions of the posts, the permittivity of a dielectric material filling the space between the posts, and on the thickness and permittivity of the top dielectric slab. Due to the high effective permittivity, a substantial reduction in the dimensions of the microwave circuit elements is possible. Two 3 dB branch line couplers were designed, fabricated and measured by applying the microstrip line on this artificial dielectric substrate.

Compact Band-stop Filter Using an Interdigital DGS Structure

  • Autoři: Balalem, A., Ali, A.R., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. p. 175-178. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper introduces compact band-stop filters using interdigital DGS slots. The slots are etched in the ground under the 50-ohm microstrip transmission line. The two filters were realized by etching two and three slots. Both filters have lower cut-off frequency at about 4.6 GHz, and higher cut-off frequency of 7.2 GHz. A good agreement was achieved between the simulated and measured results.

Coupling of Split Ring Resonators in a Mu-negative Volumetric

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Bláha, M.
  • Publikace: 2008 IEEE MTT-S International Microwave Symposium Digest. Piscataway: IEEE, 2008. p. 327-330. ISSN 0149-645X. ISBN 978-1-4244-1781-0.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents an experimental and theoretical study of the coupling of split ring resonators, and aims to show ways to widen the frequency band of the response of mu-negative metamaterials. The behaviour of these metamaterials is theoretically described in terms of coupled resonant circuits theory. In particular the coupling is studied on pairs of split ring resonators and systems containing the greater number of resonators. Widening of the metamaterial response frequency band is caused primarily by dispersion of the resonant frequencies of the particular resonators, and to a minor extent by mutual coupling.

Doppler Spread Estimation for OFDM Systems Using Newton Polynomials

  • Autoři: Ali, A.R., Balalem, A., Khanzada, T., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: Proceedings of the 18th International Conference Radioelektronika 2008. Praha: Československá sekce IEEE, 2008. p. 151-154. ISBN 978-1-4244-2087-2.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a method of estimating the Doppler spread for OFDM systems in rapidly time-variant channels. The method utilizes an approximation of the time variation of the channel by considering few Newton polynomials over few successive OFDM symbols. Doppler spread is estimated in the frequency domain from the off-diagonals of the approximated channel matrix.

Dual-band Bandpass Filter by Using Square Loop Dual-mode Resonator

  • Autoři: Balalem, A., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: Microwave and Optical Technology Letters. 2008, 50(6), 1567-1570. ISSN 0895-2477.
  • Rok: 2008
  • DOI: 10.1002/mop.23427
  • Odkaz: https://doi.org/10.1002/mop.23427
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a dual-band bandpass filter by introducing transmission zeroes in the passband of a broadband bandpass filter using square-loop dual-mode resonators. The transmission zeroes are achieved by using a dual-mode resonator. The dual-mode resonator is attached to two transmission lines of same length. These lines are coupled to similar transmission lines that are attached to the I/O ports. The filter has a compact size, low losses, and good rejection between the two bands.

Inverted Defected Ground Structure for Microstrip Line Filters Reducing

  • Autoři: Balalem, A., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: Asia Pacifik Microwave Conference 2008 - Proceedings. Hong Kong: University of Hong Kong, 2008. p. 259-262. ISBN 978-1-4244-2641-6.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new defected ground structure for microstrip line circuits was introduced by keeping the ground plane of the circuit fully metallized and etching the slots on the superstrate, which is directly lain on the top of the substrate. The structure has the great advantage in reducing the packaging complexity. The low-pass filter based on this structure was designed, fabricated and measured.

Isotropic Single Negative Metamaterials

  • Autoři: prof. Ing. Jan Macháč, DrSc., Protiva, P., Rytíř, M., Bláha, M., Zehentner, J.
  • Publikace: Radioengineering. 2008, 17(3), 1-7. ISSN 1210-2512.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the application of simple, and therefore cheap, planar resonators for building 3D isotropic metamaterials. These resonators are: a broadside-coupled split ring resonator with a magnetic response providing negative permeability; an electric dipole terminated by a loop inductor together with a double H-shaped resonator with an electric response providing negative permittivity. Two kinds of 3D isotropic single negative metamaterials are reported. The first one consists of unit cells in the form of a cube bearing on its faces six equal planar resonators with tetrahedral symmetry. In the second material, the planar resonators boxed into spherical plastic shells and randomly distributed in a hosting material compose a real 3D volumetric metamaterial with an isotropic response. The experiments prove the isotropic behavior of the cells and of the metamaterial specimens.

Low-loss Doubly Metalized CPW Low-pass Filter with Additional Transmission Zeros

  • Autoři: Balalem, A., prof. Ing. Jan Macháč, DrSc., Kim-Fai, W., Omar, A.
  • Publikace: Microwave and Optical Technology Letters. 2008, 50(5), 1431-1433. ISSN 0895-2477.
  • Rok: 2008
  • DOI: 10.1002/mop.23386
  • Odkaz: https://doi.org/10.1002/mop.23386
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This article modifies the classical CPW low-pass filter to doubly metallized CPW, by implementing metallic patches at the backside of the substrate. Moreover, transmission zeroes are introduced by using single, dual, and tri-resonant stubs. These stubs are built on the rear side of the substrate. The filters are compact in distinction to the standard CPW low-pass filter and have a very low loss compared with some other structures.

Microstrip-CPW Bandpass Filter for Antenna Application

  • Autoři: Balalem, A., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: Microwave and Optical Technology Letters. 2008, 50(1), 51-55. ISSN 0895-2477.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This article presents a quasi-lumped bandpass filter with CPW-microstrip ports. The structure serves as CPW-microstrip transmission in addition to its filtering function. The filter was integrated with a microstrip patch antenna. To enable the filter design, the characteristic impedance of the slotted microstrip line and the coupling strength of microstrip to microstrip, CPW to CPW and microstrip to CPW transitions were calculated.

Miniaturized Microstrip Lowpass Filter with Wide Stopband Using Suspended Layers and Defected Ground Structure (DGS)

  • Autoři: Boutejdar, A., prof. Ing. Jan Macháč, DrSc., Haiwen, L., Omar, A.
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. pp. 289-292. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, a novel compact wideband high-rejection LPF using defected ground structure (DGS) is presented. The proposed LPF consists of Hi-Lo etched slots in ground metallic plane as defected ground structure(DGS) and of microstrip Hi-Lo structure, which corresponding to capacitance and Inductance on the top layer. The effect of the DGS slot on the characteristics of the investigated filter is examined. In this work we have proposed a simple method to realize a compact DGS LPF with good characteristics. Measured results are found to be in good agreement with the simulation results.

Modes on a Conductor-Backed Slotline

  • Autoři: prof. Ing. Jan Macháč, DrSc., Kotlan, V., Šnajdr, M.
  • Publikace: Progress In Electromagnetics Research B. 2008, 2008(9), 151-164. ISSN 1937-6472.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper reports on an experimental investigation of modes propagating along a conductor-backed slotline: the dominant mode, and the surface leaky mode. The measurement and the numerical experiments performed in the CST Microwave Studio verify theoretical findings of modes obtained by the method of moments applied in the spectral domain. The dispersion characteristic of the dominant mode on the conductor-backed slotline is determined by substituting this line by a flat slotted waveguide.

New Compact Coplanar Bandpass Filter Composed of Serpentine Shape Shunt-Stubs

  • Autoři: Batmanov, A., Bountejdar, A., prof. Ing. Jan Macháč, DrSc., Omar, A., Burte, E.
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. p. 183-186. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a design of a new compact bandpass filter in coplanar waveguide implementation composed of serpentine shape shunt-stab. The serpentine shape shunt-stabs allow to increase the inductive loading and thus to reduce the size of the filter. The proposed filter has two transmission zeros on the both sides of the passband. The equivalent circuit model has been proposed to describe the filter behavior. The measured center frequency, bandwidth and insertion loss are 5 GHz, 50 % and 0.5 dB, respectively. The geometrical size of the proposed filter is 20x13.2 mm2. Good agreements between both measured and simulated results have been observed.

Universal Generator of Ultra-Wideband Pulses

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    An Ultra-Wideband (UWB) subnanosecond pulse generator is described in this paper. High amplitude Gaussian pulses are generated by a Step Recovery Diode (SRD) included in a novel pulse forming circuit. The proposed circuit solution utilizes the performance of the SRD effectively, without excessive requirements regarding the driver section of the generator. Monocycle pulses are then generated by an additional pulse forming network. A simple transistor driver is also described, which transforms a TTL trigger signal to a driving pulse with the timing and amplitude parameters required by the SRD. Measurement results are presented, which show the proposed generator operating with stable output pulse parameters at arbitrary pulse repetition frequency up to 20 MHz. The generated monocycle pulses are 25 V in amplitude and approximately 500 ps in width.

A Magnetic Metamaterial Composed of Randomly Oriented SRRs

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The concept, manufacture and testing of a volumetric isotropic magnetic metamaterial composed of randomly distributed broadside coupled split ring resonators is presented in this paper. An estimate of the isotropy based on the measured transmissions is made in terms of the arithmetic mean value and the standard deviation of the sample. We offer conclusions and recommendations for the development of a genuine bulk isotropic medium of various densities and distributions of the particles, based on the 64 measured frequency responses of each sample.

Artificial Dielectric Substrate for Microwave Applications

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Proceedings of AMTEE ´07 - Advanced Methods in the Theory of Electrical Engineering. Plzeň: ZČU Plzeň, 2007. pp. VII-3-VII-4. ISBN 978-80-7043-564-9.
  • Rok: 2007
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a new version of an artificial dielectric substrate. The substrate is fabricated as a 2D array of metallic posts separated from the top conductor by a thin dielectric slab. This structure can show a very high effective permittivity. This permittivity depends on the dimensions of the posts, the permittivity of a dielectric material filling the space between the posts, and on the top dielectric slab thickness and permittivity. The thinner is this slab and the higher is its permittivity the higher is the effective permittivity. This artificial dielectric substrate is suitable for designing the microstrip line and circuits based on it. Due to the high effective permittivity, a substantial reduction in the dimensions of microwave circuit elements is possible. The microstrip line on the proposed substrate was fabricated and measured. The measured and calculated effective permittivity is in a good accord.

Metamaterials - A Challenge for Contemporary Advanced Technology

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Metamaterials are artificial composite media exhibiting electromagnetic responses that natural materials do not provide. They enable their permittivity and permeability to be cast down to negative values. Metamaterials are known in two forms: volumetric medium and planar version. The first form is characterized by field theory, while the second form utilizes transmission line theory. There is a brief report on the authors' innovative findings. It concerns the utilization of split ring resonators in isotropic negative permeability metamaterials, an isotropic negative permittivity medium, CPW supporting a left-handed wave, and wire media exhibiting negative permittivity. Finally, prospects for further developments in this interesting field are presented.

Microwave Reflectivity From Gold Sputtered Nanolayer

  • Autoři: Buchar, P., prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: IEEE Transactions on Nanotechnology. 2007, 6(6), 645-651. ISSN 1536-125X.
  • Rok: 2007
  • DOI: 10.1109/TNANO.2007.907252
  • Odkaz: https://doi.org/10.1109/TNANO.2007.907252
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper deals with reflectivity of a gold layer of nanometer-scale thickness sputtered on a dielectric foil at microwave frequencies. A model of nanometer-scale spheres characterizes the behavior of the layer. For short sputtering times, these spheres are separated, and later they touch each other to form a continuous layer. The structure > is analyzed in several ways. The first model, as suggested in the literature, replaces the spheres by their electric dipole moments, while the second, newly proposed model replaces them by their mutual capacities. The structure is also being investigated by the CST Microwave Studio software. The data provided by the models is compared with the data obtained from measurements published previously. The reduction in effective conductivity of the layer due to microscopic phenomena in thin films is taken into account in the models. The measured conductivity is compared with values taken from the literature, and the differences are discussed.

Novel Entire Top Surface Planar Leaky Wave Antenna

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Zabloudil, P.
  • Publikace: Conference Proceedings - European Microwave Week 2007 (37th EuMC, EuRAD, EuMIC, EuWT). London: Horizon House Publications, 2007. p. 372-375. ISBN 978-2-87487-000-2.
  • Rok: 2007
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the application of a flat waveguide with a longitudinal slot in the middle of its wider wall for the design of a leaky wave antenna. The antenna is fed from a coaxial connector on its bottom, and provides a totally flat top surface and a radiation pattern with better suppression of side lobes than in the case of an antenna fed via a CPW patch. Its measured characteristics are in accord with those predicted by simulation.

Particle for an Isotropic Metamaterial with Negative Permittivity

  • Autoři: Protiva, P., prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Proceedings of EMTS 2007 - International URSI Commission B - Electromagnetic Theory Symposium. Manitoba: University of Manitoba, 2007. ISBN 978-0-9738425-3-1.
  • Rok: 2007
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A particle showing negative effective permittivity in some frequency band is presented in this paper. This particle is suitable for making up an isotropic epsilon-negative metamaterial. The unit cell of this metamaterial consists of a cube bearing the proposed particle on its faces with specific orientations. An experiment verified that this unit cell shows an isotropic response. The particle is also proposed in a reduced size. Its dimensions are now three times smaller than those of the original particle.

Propagation of Electromagnetic Waves within a Triple Wire Medium

  • Autoři: Hudlička, M., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of 17th International Conference Radioelektronika 2007. Brno: FEKT VUT v Brně, 2007. p. 281-285. ISBN 978-1-4244-0821-4.
  • Rok: 2007
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper a triple wire medium is described as an isotropic negative dielectric permittivity medium. A numerical experiment was performed to validate the propagation of electromagnetic waves inside the wire mesh both below and above the plasma frequency. For a practical realization, a form of the triple wire medium using a planar technology is proposed.

Quasi-Elliptic Microstrip Low-Pass Filters Using an Interdigital DGS Slot

  • Autoři: Balalem, A., Ali, R.A., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: IEEE Microwave and Wireless Components Letters. 2007, 2007(17), 586-588. ISSN 1531-1309.
  • Rok: 2007
  • DOI: 10.1109/LMWC.2007.901769
  • Odkaz: https://doi.org/10.1109/LMWC.2007.901769
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This letter introduces a DGS slot with an interdigital shape. The resonant frequency of the slot can be easily controlled by changing the length of the metal fingers, without changing the area taken by the structure. Using this slot, two quasi-elliptic lowpass filters were designed, fabricated and tested. The filters have a cut-off frequency of about 3 GHz.

Quasi-Lumped Filters on Doubly Metallized Planar Lines

  • Autoři: Balalem, A., prof. Ing. Jan Macháč, DrSc., Omar, A.
  • Publikace: Proceedings of 17th International Conference Radioelektronika 2007. Brno: FEKT VUT v Brně, 2007. p. 299-301. ISBN 978-1-4244-0821-4.
  • Rok: 2007
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents compact filters for CPW and microstrip applications. The filter elements are based on quasi-lumped concepts. Moreover, the filters are designed on the both sides of the substrate. Good agreement between the simulated and measured results is achieved.

Triple Wire Medium for Use in Isotropic Metamaterials

  • Autoři: Hudlička, M., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Conference Proceedings - European Microwave Week 2007 (37th EuMC, EuRAD, EuMIC, EuWT). London: Horizon House Publications, 2007. pp. 628-631. ISBN 978-2-87487-000-2.
  • Rok: 2007
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper a triple wire medium is described as an isotropic negative permittivity medium. A numerical experiment was performed to validate the propagation of electromagnetic waves inside the wire lattice below the plasma frequency, where the effective medium permittivity is negative. For a practical realization, a form of the triple wire medium using a planar technology was designed, fabricated and measured.

A Triple Wire Medium as an Isotropic Negative Permittivity Metamaterial

  • Autoři: Hudlička, M., prof. Ing. Jan Macháč, DrSc., Nefedov, I.S.
  • Publikace: Progress In Electromagnetics Research. 2006, 2006(65), 233-246. ISSN 1559-8985.
  • Rok: 2006
  • DOI: 10.2528/PIER06102703
  • Odkaz: https://doi.org/10.2528/PIER06102703
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents an effective medium approach to calculate the attenuation and phase constants of modes in a 3D connected wire medium both below and above the plasma frequency. Physical and nonphysical modes in the structure are identified for all the important lattice directions. According to this,the medium behaves as an isotropic material in the vicinity of the plasma frequency. These results were compared with the numerical simulation and it was observed that the wave spreads below the plasma frequency along all the important lattice directions with the same attenuation constant. This implies isotropic behavior of the 3D wire lattice below the plasma frequency,and thus this medium can be considered as an isotropic negative permittivity medium.

Bandpass Filters on a Modified Multilayer Coplanar Line

  • Autoři: Balalem, A., Hamad, E.K.I., prof. Ing. Jan Macháč, DrSc., Omar, A.S.
  • Publikace: 2006 IEEE MTT-S International Microwave Symposium Digest. Piscataway: IEEE Microwave Theory and Techniques Society, US, 2006. pp. 531-534. ISBN 978-0-7803-9541-1.
  • Rok: 2006
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The design of compact multilayer coplanar line bandpass filters is presented. These very compact filters make use of the two sides of the substrate of the modified coplanar line. In addition, a transmission zero has been introduced to the filter response, either by extending the metalization under the ground planes, or by employing additional capacitive coupling between the different parts of the filter structure. A good agreement between the simulated and measured responses has been achieved.

Computer Controlled Measurement of Electromagnetic Fields

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a system for measuring high frequency electromagnetic fields fully controlled by a computer. A measuring probe is driven in one direction by a step motor, and in two other directions it is set manually. The paper collects some experimental data on field distributions taken along a transmission line and a leaky wave antenna.

Low Profile Slotted Flat Waveguide Leaky Wave Antenna

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Zabloudil, P.
  • Publikace: 2006 IEEE MTT-S International Microwave Symposium Digest. Piscataway: IEEE Microwave Theory and Techniques Society, US, 2006. p. 1303-1306. ISBN 978-0-7803-9541-1.
  • Rok: 2006
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the application of a flat waveguide with a longitudinal slot in the middle of its wider wall for the design of a leaky wave antenna. The antenna radiates into one relatively narrow main beam and its gain is 14.2 dB at 4.75 GHz. The characteristics and radiation aspects of the antenna are discussed. The measured antenna characteristics are in accord with those predicted by simulation.

Microstrip Line on an Artificial Dielectric Substrate

  • DOI: 10.1106/LMWC.2006.877120
  • Odkaz: https://doi.org/10.1106/LMWC.2006.877120
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This letter presents a new version of an artificial dielectric substrate and a microstrip line built on top of this substrate. The substrate is fabricated as a two-dimensional array of metallic posts separated from the top conductor by a thin dielectric slab. This structure can show a very high effective permittivity and can therefore offer a substantial reduction in the dimensions of microwave circuit elements.

Power Control in Passive Waveguide Circuits

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Zabloudil, P.
  • Publikace: 2006 Asia Pacific Microwave Conference Proceedings. Tokyo: IEICE, Institute of Electronics, Information and Communication Engineers, 2006. ISBN 4-902339-11-0.
  • Rok: 2006
  • DOI: 10.1109/APMC.2006.4429653
  • Odkaz: https://doi.org/10.1109/APMC.2006.4429653
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new concept of a passive waveguide reflection attenuator and a T-junction with a variable ratio of the output powers is reported here. A conductive uniform linear polarization grid of nano thickness is inserted into the standard rectangular waveguide. Rotation of the grid results in a change of the output powers. The measured scattering matrix elements compare well with the computer simulation, confirming the expected characteristics of the two circuits.

Reflectin from a Gold Sputtered Thin Layer

  • Autoři: Buchar, P., prof. Ing. Jan Macháč, DrSc., Zehentner, J., Slepička, P., Švorčík, V.
  • Publikace: Conference Proceedings - MIKON 2006. Warsaw: Telecommunication Research Institute, 2006. p. 641-644. ISBN 83-906662-7-8.
  • Rok: 2006
  • DOI: 10.1109/MIKON.2006.4345261
  • Odkaz: https://doi.org/10.1109/MIKON.2006.4345261
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the results of an investigation of a thin layer of gold sputtered on a dielectric foil. This layer is modeled by nanometer-scale spherical particles that are separated at short deposition times and later touch each other, forming a continuous layer. Four ways of analyzing the structure are introduced. The first method describes the spheres by their electric dipole moment, while the second, newly proposed method, takes into account the capacity between adjacent spheres,and the third method assumes the layer as homogeneous and considers its reduced conductivity dueto the behavior of electrons in thin films. The CST Microwave Studio model, which takes into accountthe random distribution of particles, offers the reflection coefficient that best fits measured data.

Slotline Leaky Wave Antenna with a Stacked Substrate

  • Autoři: prof. Ing. Jan Macháč, DrSc., Hruška, J., Zehentner, J.
  • Publikace: PIERS 2006: Progress in Electromagnetics Research Symposium Proceedings. Cambridge, MA: The Electromagnetics Academy, 2006. pp. 283-287. ISSN 1931-7360. ISBN 1-933077-08-5.
  • Rok: 2006
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a new version of a leaky wave antenna based on a conductor backed slotline with a stacked substrate. The antenna radiates due to a first order space leaky wave excited on a slotline with a wide slot. The main lobe of the radiation pattern is relatively wide and there is an intensive radiation to a backward direction and below the substrate. This parasitic radiation is reduced by 7 dB by adding a simple reflector. The reflector is created by shaping the background metal layer. Producing this background layer larger than the substrate additionally reduces the radiation below the substrate by 3 dB. The reflector moreover reduces the width of the main beam.

Slotline Leaky Wave Antenna with a Stacked Substrate

  • Autoři: prof. Ing. Jan Macháč, DrSc., Hruška, J., Zehentner, J.
  • Publikace: Journal of Electromagnetic Waves and Applications. 2006, 20(12), 1587-1596. ISSN 0920-5071.
  • Rok: 2006
  • DOI: 10.1163/156939306779292309
  • Odkaz: https://doi.org/10.1163/156939306779292309
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a new version of a leaky wave antenna based on a conductor backed slotline with a stacked substrate. The antenna radiates due to a first order space leaky wave excited on a slotline with a wide slot. The main lobe of the radiation pattern is relatively wide and there is an intensive radiation to a backward direction and below the substrate. This parasitic radiation is reduced by 7 dB by adding a simple reflector. The reflector is created by shaping the background metal layer. Producing this background layer larger than the substrate additionally reduces the radiation below the substrate by 3 dB. The reflector moreover reduces the width of the main beam.

Sphere-Array Model of Microwave Reflectivity from a Thin Sputtered Gold Layer

  • Autoři: Buchar, P., prof. Ing. Jan Macháč, DrSc., Zehentner, J., Slepička, P., Švorčík, V.
  • Publikace: Proceedings of Radioelektronika 2006. Bratislava: Slovenská technická univerzita, 2006. pp. 304-307 . ISBN 80-227-2388-6.
  • Rok: 2006
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents methods for calculating the reflectivity from a sputtered gold layer. The layer is modeled by a set of nanometer-scale spherical particles. The results are compared with simulation and with measured data.

Use of Nano-Grid in a Waveguide

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Zabloudil, P.
  • Publikace: Proceedings of the 36th European Microwave Conference. Piscataway: IEEE, 2006. pp. 111-113. ISBN 2-9600551-6-0.
  • Rok: 2006
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new concept of passive waveguide circuits is presented. It is based on a combination of the standard rectangular waveguide with a metal uniform linear polarization grid of nano thickness. The grid is deposited on a polymer foil and inserted into the waveguide allowing its rotation between two opposite flanges. The concept is demonstrated on T-junction with adjustable ratio of output powers and on a variable reflection attenuator. Both circuits were designed, manufactured and tested. Measured characteristics compare well with computer simulations and confirmed expected behavior of both circuits.

A Novel Bulk Left-Handed Structure

  • Autoři: Buchar, P., prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: The 13th Conference on Microwave Techniques - COMITE 2005. Praha: IEEE Czechoslovakia Section, 2005. pp. 76-79. ISBN 80-86582-16-7.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A novel periodic bulk structure has been proposed simulated, manufactured and measured. It consists of parallel-plate waveguides cut by short-circuited stubs representing series capacities and shortcircuited by wires representing shunt inductances. It has been shown that this structure behaves as a left-handed material (LHM) having a negative effective index of refraction and supporting backward wave propagation in an approx. 4.7 - 5.7 GHz frequency band.

Coplanar Waveguide Transmitting a Left-Handed Wave

  • Autoři: prof. Ing. Jan Macháč, DrSc., Hudlička, M., Zehentner, J., Spiliotis, N.G., Omar, A.S.
  • Publikace: European Microwave Week 2005 Conference Proceedings. London: Horizon House Publications, 2005. pp. 137-140. ISBN 2-9600551-2-8.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a new version of a coplanar waveguide that transmits a left-handed wave. The equivalent circuit of the line unit cell has been derived from the shape of the layout. The values of its elements were determined by fitting the dispersion characteristic of the equivalent circuit to the dispersion characteristic of the first left-handed mode of the line calculated by the CST Microwave Studio. This dispersion characteristic was checked by an experiment. The measured frequency dependences of S11 and S21 fit well the data predicted by simulation. The line is uniplanar and does not contain any lumped elements or vias.

Determination of the Equivalent Circuit of the Left-Handed Coplanar Waveguide

  • Autoři: Hudlička, M., prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: The 13th Conference on Microwave Techniques - COMITE 2005. Praha: IEEE Czechoslovakia Section, 2005. pp. 139-142. ISBN 80-86582-16-7.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A simple equivalent circuit of a left-handed coplanar waveguide is presented in this paper. Approsimate dependences of the equivalent circuit element values on physical dimensions of the left-handed coplanar waveguide are presented. The dispersion characteristics computed with the aid of the equivalent circuit is aimed to represent the properties of the fabricated left-handed coplanar waveguide.

Disperzní charakteristiky struktur vykazujících zápornou permitivitu a permeabilitu

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Buchar, P., Hudlička, M.
  • Publikace: Odborné semináře - Sborník za rok 2004/2005. Praha: Československá sekce IEEE, 2005. pp. 8-12. ISBN 80-86582-17-5.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    V příspěvku jsou vypočteny disperzní charakteristiky vybraného metamateriálu, který je prezentován páskovým vedením s horním páskem periodicky přerušovaným příčnými štěrbinami. Mezi štěrbinami jsou umístěny zkratovací kolíčky. Disperzní charakteristiky tohoto vedení vypočtené pomocí programu Microwave Studio jsou porovnány s analyticky vypočtenou charakteristikou periodického prostředí a s fázovou konstantou homogenního vedení, které reprezentuje periodickou strukturu za předpokladu buněk mnohem kratších než je vlnová délka. Je určeno frekvenční pásmo, ve kterém vedení přenáší zpětnou vlnu.

Flat Waveguide with a Longitudinal Slot

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J.
  • Publikace: 2005 IEEE MTT-S International Microwave Symposium. Piscataway: IEEE, 2005. pp. 1909-1012. ISBN 0-7803-8845-3.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents an analysis of a flat slotted waveguide by the spectral domain method finalized by a complex root search procedure. Matching of fields from bounded and unbounded regions at the common interface is explained and applied to satisfy the boundary conditions in the spectral domain. New theoretical findings are reported, and the dispersion characteristics of particular modes are shown and discussed with regard to their potential application. The different behaviour of the odd and even modes is pointed out. Their affinity to the modes in a standard rectangular waveguide is noted. A hint is given of a modification of the line cross-section resulting in the propagation of a bound mode besides the propagation of the space leaky modes.

Fourier Transformation and Boundary Conditions in the Spectral Domain

  • Autoři: Zehentner, J., Mrkvica, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: PIERS 2005. Cambridge, MA: The Electromagnetics Academy, 2005.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The Fourier transform into the spectral domain provides a solution of the wave equation. Boundary conditions enable the integral and separation constants to be determined. Their formulation is not easy particularly when radiation from the bound region to the boundless region is investigated. The method is applied to the rectangular waveguide with a longitudinal slot cut in the middle of the wider wall.

Left-Handed Coplanar Waveguide

  • Autoři: prof. Ing. Jan Macháč, DrSc., Hudlička, M., Zehentner, J., Spiliotis, N.G., Omar, A.S.
  • Publikace: 2005 IEEE MTT-S International Microwave Symposium. Piscataway: IEEE, 2005. pp. 1957-1960. ISBN 0-7803-8845-3.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper proposes a new version of a left-handed coplanar waveguide. The line has a fully uniplanar structure without vias and lumped elements. The series capacitors are represented by interdigital capacitors and the parallel inductors by short circuited CPW stubs connected to a ground metallization. The measured frequency dependences of S21 and S11 agree well with the data predicted by simulation. The simple equivalent circuit of the line unit cell was set up by fitting its dispersion characteristic to the dispersion characteristic of the first left-handed mode calculated by the CST Microwave Studio.

Microwave Structures with Left-Handed Characteristics

  • Autoři: Buchar, P., Hudlička, M., prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Radioelektronika 2005 - Conference Proceedings. Brno: VUT v Brně, FEI, Ústav radioelektroniky, 2005. pp. 267-270. ISBN 80-214-2904-6.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Two structures with left-handed characteristics are presented in this paper. They are in planar form or bulk form. The dispersion characteristics of the two structures have been computed and the propagation of a left-handed wave is demonstrated.

New Bulk Metamaterial

  • Autoři: prof. Ing. Jan Macháč, DrSc., Buchar, P., Zehentner, J., Omar, A.S.
  • Publikace: European Microwave Week 2005 Conference Proceedings. London: Horizon House Publications, 2005. pp. 713-716. ISBN 2-9600551-2-8.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Design, analysis, fabrication and measurement of a new bulk metamaterial is reported in this paper. The structure of the new medium is made up of left-handed parallel strips. The series capacitors are realized by short circuited parallel strip stubs, and the conducting shunt pins represent parallel inductors. This metamaterial allows the propagation of a left-handed wave in the frequency band from 4.75 to 5.65 GHz, much wider than the frequency band achievable by split-ring resonators. The simple equivalent circuit of the metamaterial is derived. Additional modification of the media structure is proposed.

New Planar and Volume Versions of a Metamaterial

  • Autoři: prof. Ing. Jan Macháč, DrSc., Hudlička, M., Buchar, P., Zehentner, J.
  • Publikace: Radioengineering. 2005, 14(4), 105-112. ISSN 1210-2512.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Some characteristics of materials with negative permittivity and permeability, i.e., with a negative refractive index, known as metamaterials, are presented in this paper. Dispersion characteristics of left-handed parallel strips calculated by different methods are compared with each other. The calculated and measured dispersion and transmission characteristics of a newly proposed left-handed coplanar waveguide and of a novel volume metamaterial are shown. Simple equivalent circuits of both structures are presented together with elements values. The structures exhibit a negative refractive index in a wide frequency band.

Periodic Structures with a Negative Refractive Index

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Buchar, P., Hudlička, M.
  • Publikace: AMTEE´05. Plzeň: Západočeská univerzita v Plzni, 2005. pp. D57-D63. ISBN 80-7043-392-2.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents dispersion characteristics of metamaterials with negative permittivity and permeability, i.e., with a negative refractive index. The dispersion characteristics of left-handed parallel strips calculated by different methods are compared with each other. The calculated and measured dispersion characteristics of a new proposed left-handed coplanar waveveguide and of a new volume metamaterial are shown. These media show a negative refractive index in a wide frequency band.

Planar Slotted Lines with Finite Width of the Substrate

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J.
  • Publikace: Proceedings - XXVIIIth General Assembly of International Union Radio Science (URSI). Ghent: URSI, 2005.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper uses the spectral domain method to analyse a flat rectangular waveguide with a slotted partition in the H plane and a waveguide with the longitudinal slot in its wider wall. Even and odd modes have been identified on both guides and their suitability for practical utilization in circuits is shown. Our calculated propagation constants compare well with data published elsewhere. The analysis provides a new view on the field propagation in the slotted waveguide that is in accord with its hitherto known behavior.

Planar Transmission Lines in MW and MMW Circuits

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J.
  • Publikace: TELSIKS 2005 - Proceedings of Papers - Volume 1. Piscataway: IEEE, 2005. pp. P-III-P-XI. ISBN 0-7803-9164-0.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The analysis of open, particularly slotted planar transmission lines in a wide frequency range is presented in this paper. The full wave approach by the spetral domain method is applied. Theoretical findings and their practical consequences are reported. Some outputs from the CST Microwave Studio and from our Analysis of Planar Transmission Lines package are shown.

Analysis and Design of Open Planar Transmission Lines

  • Autoři: Zehentner, J., Mrkvica, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: East-West Workshop - Advanced Techniques in Electromagnetics. Warsaw: University of Technology, 2004. pp. 234-240.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The APTL (Analysis of Planar Trans- mission Lines) package contains an analysis of 18 different planar transmis-sion lines. The program is based on the spectral domain method. The code provides the frequency dependent propagation con-stant of a selected mode, the characteristic impedance when it can be de-fined, the field distribution in the cross-section and the distribution of the transversal field component within a slot, or the current density component on the strip.

Analýza planárních vedení - program APTL

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J.
  • Publikace: Sborník vzdělávacích a vědeckovýzkumných činností a nabídek. Praha: IEEE Czechoslovakia Section, 2004. pp. 36-39. ISBN 80-86582-15-9.
  • Rok: 2004

Conductor-Backed Slotline Antenna

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Hruška, J.
  • Publikace: European Microwave Week 2004 - Conference Proceedings. 2004. pp. 1205-1208. ISBN 1-58053-994-7.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A conductor-backed slotline leaky wave antenna and its modifications were designed, produced and measured. The modified antennas are characterized by one or two additional dielectric layers placed on the top surface of the original structure. These layers adjust the form of the dispersion characteristics of the line, influence the width of the frequency band, reduce/enhance the scanning sensitivity of the main beam, and change its shape.

Coplanar Leaky Wave Antenna

  • Autoři: Hudlička, M., prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Conference Proceedings of Radioelektronika 2004. Bratislava: Slovak University of Technology, 2004. pp. 229-232. ISBN 80-227-2017-8.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the results of an investigation of a coplanar leaky wave antenna with wide slots. The antenna radiation is based on excitation of a space leaky wave of the first order. A prototype coplanar leaky wave antenna was designed, fabricated and then measured.

Dispersion Characteristics of the Dominant Mode on a Completely Shielded Conductor-Backed SLotline

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J.
  • Publikace: 2004 IEEE MTT-S International Microwave Symposium. 2004. pp. 507-510. ISBN 0-7803-8332-X.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents an analysis of a completely shielded conductor-backed slotline using the spectral domain technique. Attention is paid to dominant and higher order modes with even symmetry of the transversal electric field component in the slot parallel to the dielectric interface. The dependence of the phase constant and the characteristic impedance of the line on cross-sectional size, permittivities and frequency are given. It has turned out that the line is suitable for circuit design when the dominant requirement is for low characteristic impedance. Numerical examples highlight particular aspects of the mode propagation over the line. The consequence of setting e0 in the whole cross-section of the line is a waveguide containing a partition in the H plane with a longitudinal slot. An analysis of this quide by the spectral domain method is presented and typical frequency dependent phase constant and characteristic impedance patterns are shown.

Disperzní charakteristiky struktur vykazujících zápornou permitivitu a permeabilitu

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Buchar, P., Hudlička, M.
  • Publikace: Zborník príspevkov na 2. konferencii s výstavou Mikrovlnová a bezdrotová technika 2004. Košice: TU Košice, FEI, 2004. pp. 39-42. ISBN 80-88922-87-9.
  • Rok: 2004

Experimental Exploration of Gold Sputtered Layer Behaviour at Microwave Frequency

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Langer, V., Hudlička, M., Švorčík, V., Slepička, P., Drbohlav, I.
  • Publikace: EMFM 2004 - Conference Proceedings. Warsaw: Telecommunication Research Institute, 2004. pp. 105-108.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The electrical characteristics of an ultra thin gold layer deposited by sputtering on polyethylenterephtalate foil have been examined experimentally at microwave frequencies. Dramatic changes with sputtering time were observed. It turned out that the highest power absorption requirement and the optimal sheet resistance for heating do not coincide, so a balanced compromise needs to be reached. Exploration of ultra thin films by microwaves is and efficient and inexpensive diagnostic method.

Planární obvody pro techniku cm a mm vln

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Sborník vzdělávacích a vědeckovýzkumných činností a nabídek. Praha: IEEE Czechoslovakia Section, 2004. pp. 19-20. ISBN 80-86582-15-9.
  • Rok: 2004

Přehled základních numerických metod výpočtu elektromagnetických polí

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Počítačové prostředky pro mikrovlnnou techniku. Praha: Česká elektrotechnická společnost, 2004. pp. 2-5.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Příspěvek podává přehled základních numerických metod pro výpočet rozložení elektromag. polí. Pozornost je věnována metodám konečných diferencí, konečných prvků a momentové metodě.

Program CST Microwave Studio pro výpočty 3D elektromagnetických polí mikrovlnných prvků

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Počítačové prostředky pro mikrovlnnou techniku. Praha: Česká elektrotechnická společnost, 2004. pp. 26-29.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Přednáška uvádí základní vlastnosti a možnosti simulátoru Microwave Studio pro výpočty elektromag. polí v mikrovlnné technice. Použití programu je dokumentováno na celé řadě příkladů: štěrbinová anténa, rotační koaxiální a vlnovodové spojky, objemové a planární periodické struktury.

Radiation from the Conductor-Backed Slotline

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: 2004 URSI EMTS - Proceedings. Pisa: University of Pisa, 2004. pp. 162-163.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The conductor-backed slotline radiates when the CPW feeder excites the 1st space leaky wave on the line. The leaky wave antenna on the conductor-backed slotline was designed, fabricated and measured. The modified version of the this line has an additional dielectric layer placed on the top surface of the original structure where the slot is located. This layer modifies the dispersion chacteristics of the waves.

Spectral Domain Analysis of Open Planar Transmission Lines

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents a new code calculating the basic characteristics of modes propagating on 18 types of open/shielded planar transmission lines - the microstrip line and the modifications of the slotline and the coplanar waveguide. The code outputs are: the complex propagation constant, the distribution of an electric field (current) across a slot (strip) or slots, the distribution of the vector of an electric field in the transversal plane of the line, 3D animation of the mode electric calculated for all possible modes: the bound mode, the surface leaky mode, the space leaky mode mode and higher order modes of these three groups of modes. The line analysis is based on the method of moments applied in the spetral domain. To show the code versatility a selection of examples of its outputs is presented in the paper.

Spectral Domain Analysis of Open Planar Transmission Lines

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents a new code calculating the basic characteristics of modes propagating on 18 types of open/shielded planar transmission lines - the microstrip line and the modifications of the slotline and the coplanar waveguide. The code outputs are: the complex propagation constant, the distribution of an electric field (current) across a slot (strip) or slots, the distribution of the vector of an electric field in the transversal plane of the line, 3D animation of the mode electric calculated for all possible modes: the bound mode, the surface leaky mode, the space leaky mode mode and higher order modes of these three groups of modes. The line analysis is based on the method of moments applied in the spetral domain. To show the code versatility a selection of examples of its outputs is presented in the paper.

The Design of a Leaky Wave Antenna Based on the Conductor-Backed Slotline, and Modifications to it

  • Autoři: Hruška, J., prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Conference Proceedings of Radioelektronika 2004. Bratislava: Slovak University of Technology, 2004. pp. 457-460. ISBN 80-227-2017-8.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the design of a conductor-backed slotline antenna and its succesive verification in the CST Microwave Studio. Several antennas were produced and measured. The measured parameters of the antennas fit well with their characteristics predicted by the EM simulator.

Visualization of Leaky Waves on Planar Transmission Lines

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Mrkvica, J.
  • Publikace: MIKON 2004 - Conference Proceedings. Warsaw: Telecommunication Research Institute, 2004. pp. 820-823. ISBN 83-906662-7-8.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a visualization of leaky waves excited by delta-gap sources on planar transmission lines, namely the 2nd surface and space leaky modes on the slotline, and the dominant and surface leaky modes on the conductor-backed slotline. The field is modeled by numerical calculation in the time domain. The simulations show the character of the leaky waves excited by delta-gap sources and are a useful tool for the investigation of leaky waves.

Waveguide with a Partition in the H-plane Analyzed by the Spectral Domain Method

  • Autoři: Zehentner, J., Mrkvica, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: PIERS 2004 (Nanjing) Proceedings. Cambridge: Electromagnetics Academy, 2004. pp. 142. ISBN 0-9679674-4-9.
  • Rok: 2004

A Program for Analyzing Planar Transmission Lines

  • Autoři: Mrkvica, J., Zehentner, J., prof. Ing. Jan Macháč, DrSc., Černý, P.
  • Publikace: COMITE 2003. Praha: IEEE Czechoslovakia Section, 2003. pp. 167-170. ISBN 80-86582-09-4.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper present a program for computer analysis of microwave planar transmission lines, the slotline, the coplanar waveguide, the microstrip line, the covered microstrip line and the stripline. The program utilizes the method of moments applied in the spectral domain. This analysis produces the propagation constant, the characteristic impedance of the line and the frequency band in which only the dominant mode propagates.

A Short Leaky Wave Antenna

  • Autoři: Hruška, J., prof. Ing. Jan Macháč, DrSc., Zehentner, J., Mrkvica, J.
  • Publikace: Radioelektronika 2003 - Conference Proceedings. Brno: VUT v Brně, FEI, Ústav radioelektroniky, 2003. pp. 233-236. ISBN 80-214-2383-8.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the results of an investigation of a slotline leaky wave antenna with a short slot. This antenna works by exciting a space leaky wave of the first order. A slotline leaky wave antenna was designed, produced and measured. This antenna is relatively broadband and radiates two main beams on the opposite sides of the substrate

Anténa s vytékající vlnou na jednostranně stíněném štěrbinovém vedení

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Hruška, J., Mrkvica, J.
  • Publikace: Sborník vzdělávacích a vědeckovýzkumných činností a nabídek katedry elektromagnetického pole FEL ČVUT. Praha: Československá sekce IEEE, 2003. pp. 24-28. ISBN 80-86582-13-2.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Příspěvek shrnuje výzkum vyzařování z jednostranně stíněného štěrbinového vedení na silném substrátu s nízkoupermitivitou. Toto vedení vyzařuje vlivem excitace vlny vytékající do prostoru prvního řádu. Je prezentována její disperzní charakteristika. Byla navržena, optimalizována a vyrobena anténa s vytékající vlnou na jednostranně stíněném štěrbinovém vedení. Anténa je napájena pomocí koplanárního vedení, pracuje ve frekvenčním pásmu od 4.75 do 6.5 GHz a vyzařuje do poloprostoru nad substrát. Měřený a vypočtený koeficient vstupního odrazu antény a rovněž její vypočtený a změřený vyzařovací digram se dobře shodují.

Dominantní vidy na štěrbinovém vedení a na štěrbinovém vedení se spodní metalizací

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Mrkvica, J.
  • Publikace: Odborné semináře - Sborník za rok 2002/2003. Praha: ČVUT FEL, Katedra elektromagnetického pole, 2003. pp. 3-7. ISBN 80-86582-12-4.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper compares the characteristics of the dominant bound mode propagating along the slotline with the characteristics of the even dominant mode propagating along the conductor backed slotline. The theoretically predicted modes are experimentally verified. The dominant mode on the slotline is a standard bound mode. The metallization placed on the rear surface of the dielectric sučlánku jsou porovnány vlastnosti dominantního vázaného vidu šířícího se podél štěrbinového vedení a dominantního vidu šířícího se podél štěrbinového vedení se spodní metalizací. Dominantní vid na štěrbinovém vedení je normální vázaný vid. Pokovení spodní plochy substrátu vytvářející vedení se spodní metalizací zcela mění vlastnosti tohoto vedení. Střední část struktury má nižší efektivní permitivitu než oblasti mezi vodivými vrstvami, jedná se tedy o tzv. invertovaný vlnovod. V důsledku toho není dominantní vid vázaným videm. Jeho rozložení elektromagnetického pole má v příčném směru charakter stojaté vlny.

Educational Program for Numerical Methods in Electromagnetic Field

  • Autoři: Mrkvica, J., prof. Ing. Jan Macháč, DrSc., Černý, P.
  • Publikace: Proceedings of Workshop 2003. Praha: Czech Technical University in Prague, 2003. p. 456-457. ISBN 80-01-02708-2.
  • Rok: 2003

Educational tool for the Subject "Numerical Methods in Microwave Techniques"

  • Autoři: Mrkvica, J., prof. Ing. Jan Macháč, DrSc., Černý, P.
  • Publikace: Radioelektronika 2003 - Conference Proceedings. Brno: VUT v Brně, FEI, Ústav radioelektroniky, 2003. pp. 300-303. ISBN 80-214-2383-8.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper describes the educational program that will be used in the course of Numerical Methods in the Electromagnetic Field. The program is applied to microwave technology. The objective of the program is to help students at both masters and PhD. level to gain a deeper understanding and mastery of the subject.

Interactive Course in Electromagnetic Field Theory on the Internet

  • Autoři: Jerhotová, E., prof. Ing. Jan Macháč, DrSc., doc. Ing. Vítězslav Pankrác, CSc., Spálený, P.
  • Publikace: AMTEE'03 - Sixth International Conference on Advanced Methods in the Theory of Electrical Engineering applied to power systems. Plzeň: ZČU FE, katedra teoretické elektrotechniky, 2003. pp. F23-F26. ISBN 80-7082-960-5.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper summarizes particular results achieved while working on Interactive Course in Electromagnetic Field Theory on the Internet project, which received funding for 2003 from the "Fond rozvoje vysokých škol" under grant no. FRV2449/2003. The aim of the project is to create and to present on the faculty server an interactive course in electromagnetic field theory. Students can gain practical experience and improve their knowledge of the subject. The final aim is to improve students' ability to solve general problems in electromagnetic field theory, which forms the basis of all branches of electrical engineering.

Modes on the Standard and Inverted Conductor-Backed Slotline

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J., Tuzi, C.
  • Publikace: International Microwave Symposium Digest. Piscataway: IEEE, 2003. pp. 677-680. ISSN 0149-645X.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper recalls modes which can propagate onthe conductor-backed slotline. The characterstic of the dominant mode on the CBSL is documented. The ICBSL is a modification of the CBSL placed in a dielectric with permittivity higher than the substrate permittivity. The modes on this line, including the interesting dominant leaky mode, are presented.

Planární obvody pro techniku cm a mm vln

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Sborník vzdělávacích a vědeckovýzkumných činností a nabídek katedry elektromagnetického pole FEL ČVUT. Praha: Československá sekce IEEE, 2003. pp. 29-30. ISBN 80-86582-13-2.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Projekt "Planární obvody pro techniku cm a mm vln" zahrnuje návrh a modelování planárních mikrovlnných vedení, uniplanárních antén s vytékající vlnou a jednoduchých pasivních obvodu na bázi planárních vedení. Pro zájemce nabízíme analýzu či návrh planárních obvodu, subsystému a antén s respektováním dosud opomíjeného efektu vytékání energie.

Slotline Leaky Wave Antenna

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Mrkvica, J.
  • Publikace: COMITE 2003. Praha: IEEE Czechoslovakia Section, 2003. pp. 8-16. ISBN 80-86582-09-4.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This report presents the results of our investigation of a slotline with a wide slot working in the regime of the excitation of a space leaky wave of the fist order. Both the standard and the conductor backed slotline are taken into account. The slotline leaky wave antenna has been designed, fabricated and measured. The slotline antenna radiates two main beams on the opposite sides of the substrate. The metallization on the rear side of the substrate ensures the radiation of only one main beam but completely changes the line behaviour. The possibility of the conductor backed slotline operating as a leaky wave radiator has been proved. The process of designing the conductor backed slotline antenna has not yet been completed and will be the subject of the further investigation.

The Inverted Conductor-Backed Slotline - a Challenge to Antenna and Circuit Design

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J., Tuzi, C.
  • Publikace: 33rd European Microwave Conference - Conference Proceedings. London: Horizon House Publications, 2003. pp. 73-76. ISBN 1-58053-834-7.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Characteristics of modes on the conductor-backed slotline, the inverted conductor-backed slotline and on its modification in which the top dielectric layer with higher permittivity has a finite thickness are presented in this paper. Only the modified inverted conductor-backed slotline is able to transmit the dominant bound mode. The inverted and modified inverted conductor-backed slotlines are real candidates for the design of leaky wave antennas.

Výukový program pro předmět Numerické metody v elektromagnetickém poli

  • Autoři: Mrkvica, J., prof. Ing. Jan Macháč, DrSc., Černý, P.
  • Publikace: Odborné semináře - Sborník za rok 2002/2003. Praha: ČVUT FEL, Katedra elektromagnetického pole, 2003. pp. 70-74. ISBN 80-86582-12-4.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Tento článek popisuje výukový program pro předmět Numerické metody v elektromagnetickém poli se zaměřením na mikrovlnnou techniku. Program má pomáhat studentům magisterského a doktorského studijního programu v hlubším pochopení probírané látky ve výše jmenovaném předmětu.

Comments on Representation of Surface Leaky Waves on Uniplanar Transmission Lines

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: IEEE Transactions on Microwave Theory and Techniques. 2002, 50(2), 583-585. ISSN 0018-9480.
  • Rok: 2002

Dominant Modes on the Slotline and on the Conductor-backed Slotline

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Mrkvica, J.
  • Publikace: Journal of Electrical Engineering. 2002, 53(9/s), 167-170. ISSN 1335-3632.
  • Rok: 2002
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper compares the characteristics of the dominant bound mode propagating along the slotline with the characteristics of the even dominant mode propagating along the conductor backed slotline. The theoretically predicted modes are experimentally verified. The dominant mode on the slotline is a standard bound mode. The metallization placed on the rear sufrace of the dielektric substrate, in order to create the conductor-backed slotline, completely changes the line behaviour.The conductor-backed slotline has a lower effective permittivity in the central part of the cross-section.Consequently, the dominant mode is not a bound wave. The fieeld of that mode in the transversal direction has a standing wave pattern and the transmitted energy is not bound to the central area of the line.

Dominant Modes on the Slotline and on the Conductor-Backed Slotline

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Mrkvica, J.
  • Publikace: 16th Electromagnetic Fields and Materials & Magnetic Measurements'02. Bratislava: FEI, Slovak University of Technology, 2002. pp. 61.
  • Rok: 2002

Even and ODD Modes on a Conductor-Backed Slotline

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J.
  • Publikace: 32nd European Microwave Conference Proceedings. London: CMP Europe Ltd, 2002. p. 609-612. ISBN 0-86213-208-8.
  • Rok: 2002

Experimental Verification of Theoretically Revealed Modes on the Conductor-Backed Slotline

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J., Hruška, J., Langer, V., Zabloudil, P.
  • Publikace: 2002 Asia-Pacific Microwave Conference Proceedings. Tokyo: IEICE, Institute of Electronics, Information and Communication Engineers, 2002. pp. 1200-1203.
  • Rok: 2002

Novel Selected Modes on The Conductor-Backed Slotline

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J.
  • Publikace: IMS 2002 - International Microwave Symposium Digest. Piscataway: IEEE, 2002. pp. 961-964. ISSN 0149-645X. ISBN 0-7803-7239-5.
  • Rok: 2002

Planární obvody pro techniku cm a mm vln

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: WORKSHOP - Vzdělávací fórum - nabídka aktivit. Praha: ČVUT FEL, Katedra elektromagnetického pole, 2002. p. 50-51. ISBN 80-86582-07-8.
  • Rok: 2002

Program pro analýzu uniplanárních vedení metodou momentů ve spektrální oblasti

  • Autoři: Mrkvica, J., Zehentner, J., prof. Ing. Jan Macháč, DrSc., Černý, P.
  • Publikace: Workshop CAD CAE'2002. Praha: IEEE Czechoslovakia Section, 2002. p. 9-12. ISBN 80-86582-05-1.
  • Rok: 2002

Štěrbinová anténa s vytékající vlnou

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Mrkvica, J.
  • Publikace: WORKSHOP - Grantové fórum. Praha: ČVUT FEL, Katedra elektromagnetického pole, 2002. pp. 52-61. ISBN 80-86582-06-X.
  • Rok: 2002

Uniplanar Leaky Wave Radiator

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Lorenz, P.
  • Publikace: Radioelektronika 2002. Bratislava: Slovak University of Technology, Faculty of Civil Engineering, 2002. pp. 247-250. ISBN 80-227-1700-2.
  • Rok: 2002

Wide-Slotted Printed Slotline Radiator

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Lorenz, P., Mrkvica, J.
  • Publikace: MIKON 2002 - 14th International Conference on Microwaves, Radar and Wireless Communications. Warsaw: Telecommunication Research Institute, 2002. pp. 226-229. ISBN 83-906662-5-1.
  • Rok: 2002

High Performance Computing at CTU

  • Autoři: Navrátil, J., Bittnar, Z., Votrubová, J., Vacek, V., Kozel, K., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: Proceedings of Workshop 2001. Praha: České vysoké učení technické v Praze, 2001, pp. 232-233. ISBN 80-01-02335-4.
  • Rok: 2001

Leaky Wave Radiation of a Printed Slotline Antenna

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Lorenz, P., Mrkvica, J.
  • Publikace: APMC 2001 - Proceedings. Piscataway: IEEE, 2001. pp. 1175-1178. ISBN 0-7803-7138-0.
  • Rok: 2001

Leaky Waves of the Second Order on the Slotline

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Lorenz, P.
  • Publikace: U.R.S.I. 2001 International Symposium on Electromagnetic Theory. Victoria, BC: University of Victoria, 2001. pp. 532-534. ISBN 1-55058-224-0.
  • Rok: 2001

Leaky Waves on the Uniplanar Transmission Line

  • Autoři: Mrkvica, J., Zehentner, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: COMITE 2001. Praha: IEEE Czechoslovakia Section, 2001. pp. 177-179. ISBN 80-902417-9-4.
  • Rok: 2001

Planar Slot-patch Antenna

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Lorenz, P., Mrkvica, J.
  • Publikace: Conference Proceedings - 31st EuMC 2001. London: CMP Europe Ltd, 2001. pp. 223-226. ISBN 08-62-13148-0.
  • Rok: 2001

Planární obvody pro techniku cm a mm vln

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Inovace 2001. Praha: Asociace inovačního podnikání ČR, 2001. pp. xx.
  • Rok: 2001

Přehled výsledků a úspěšných publikací dosažených s podporou IBM RS 6000/SP

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Přehled výsledků a úspěšných publikací dosažených s podporou IBM RS 6000/SP. Praha: České vysoké učení technické v Praze, 2001. pp. 20-21. ISBN 80-01-02334-6.
  • Rok: 2001

Slotline Leaky Wave Antenna

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Lorenz, P.
  • Publikace: AMTEE 01. Plzeň: Západočeská universita, 2001. pp. G27-G30.
  • Rok: 2001

Space Leakage of Power from the Slotline

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Lorenz, P.
  • Publikace: 2001 IEEE MTT-S International Microwave Symposium Digest. Piscataway: IEEE, 2001. p. 1217-1220. ISBN 0-7803-6539-9.
  • Rok: 2001

Uniplanar Slotline Microwave Circuits

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Menzel, W.
  • Publikace: Radioelektronika 2001 - Conference Proceedings. Brno: VUT v Brně, FEI, Ústav radioelektroniky, 2001. pp. 246-249. ISBN 80-214-1861-3.
  • Rok: 2001

Leaky Waves and Conditions for Exciting Them on Uniplanar Transmission Lines

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: PIERS 2000 - Progress in Electromagnetics Research Symposium. Cambridge: Electromagnetics Academy, 2000. pp. 235. ISBN 0-9679674-0-6.
  • Rok: 2000

Modelování vln šířících se planárními mikrovlnnými vedeními

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: KTEM 2000 - Seminář kateder teoretické elektrotechniky a měření elektrotechnických fakult České republiky a Slovenské republiky. Praha: České vysoké učení technické v Praze, 2000. pp. 43-47.
  • Rok: 2000

New Space Leaky Wave Spectrum Components on the Slotline

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: European Microwave Conference. Brussels: The European Microwave Association 2000, 2000. pp. 190-193. ISBN 0-86213-212-6.
  • Rok: 2000

Potential of the Slotline to Leak Power into Space

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Radioelektronika 2000 - Conference Proceedings. Bratislava: STU v Bratislave, FEI, 2000. pp. IV-22-IV-25. ISBN 80-227-1389-9.
  • Rok: 2000

Properties of CPW in the SUB-MM Wave Range and its Potential to Radiate

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: 2000 IEEE MTT-S International Microwave Symposium Digest. Piscataway: IEEE, 2000. pp. 1061-1064. ISSN 0149-645X.
  • Rok: 2000

Space Leakage of Power from Uniplanar Transmission Lines

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: MIKON 2000 - XIII International Conference on Microwaves, Radar and Wireless Communications. Warsaw: Telecommunication Research Institute, 2000. pp. 565-568. ISBN 83-906662-0-0.
  • Rok: 2000

Coplanar Line in Millimetre and Submillimetre Wave Range

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Migliozzi, M.
  • Publikace: 10th Microcoll. Budapest: Technical University, 1999. pp. 397-400. ISBN 963-420-594-1.
  • Rok: 1999

Experimental Verification of the Second Leaky Wave on the Slotline

Leaky Wave Detection by Active Radiometry

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J., Polívka, J., Sarnowski, M., Vacek, P.
  • Publikace: 9th International Czech-Slovak Scientific Conference Radioelektronika 99. Brno: VUT v Brně, 1999. pp. 249-252. ISBN 80-214-1327-1.
  • Rok: 1999

Spurious Leaky Mode Solutions and Experimental Verification of the Second Leaky Wave

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J., Vacek, P., Polívka, J.
  • Publikace: 1999 IEEE MTT-S International Microwave Symposium. Piscataway: IEEE, 1999. pp. 1261-1264. ISBN 0-7803-5136-3.
  • Rok: 1999

Upper CUT of Frequency of Bound Wave Propagation on Uniplanar Lines

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: The 10th Conference on Microwave Techniques COMITE 1999. Prague: Czechoslovakia Section IEEE, 1999. pp. 89-90. ISBN 80-902417-3-5.
  • Rok: 1999

Dispersion Characteristics of Leaky Waves on Lossless and Lossy Slotlines

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Migliozzi, M.
  • Publikace: 1998 IEEE MTT-S International Microwave Symposium Digest. Piscataway: IEEE, 1998. pp. 1795-1798. ISBN 0-7803-4472-3.
  • Rok: 1998

Field Mapping by Active Radiometry

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J., Sarnowski, M.
  • Publikace: 1998 Asia-Pacific Microwave Conference Proceedings - APMC 98. Tokyo: Waseda University, 1998. pp. 217-220.
  • Rok: 1998

Leakage in to Several Surface Waves on Open Planar Transmission Lines

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Migliozzi, M.
  • Publikace: Proceedings of International Symposium on Electromagnetic Theory. Thessaloniki: Aristotle University of Thessaloniki, 1998. pp. 500-502.
  • Rok: 1998

Leaky Waves on the Slotline

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Migliozzi, M.
  • Publikace: Workshop 98. Praha: České vysoké učení technické v Praze, 1998. pp. 251-252.
  • Rok: 1998

Performance of the Slotline in the mm-wave Range

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Migliozzi, M.
  • Publikace: MIKON 98 International Conference on Microwaves and Radar. Warsaw: Telecommunication Research Institute, 1998. pp. 481-485. ISBN 83-906662-0-0.
  • Rok: 1998

Radiometric Detection of Surface Leaky Waves

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J., Polívka, J., Sarnowski, M.
  • Publikace: 43. Internationales Wissenschaftliches Kolloquium. Ilmenau: TU Ilmenau, 1998. pp. 295-300. ISSN 0943-7207.
  • Rok: 1998

Surface Leaky Waves and Their Measurement

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Mrkvica, J., Sarnowski, M., Polívka, J.
  • Publikace: 28th European Microwave Conference 98. London: Miller Freeman UK, 1998. pp. 561-564. ISBN 0-86213-141-3.
  • Rok: 1998

Upper Cutoff Frequency of the Bound Wave and New Leaky Wave on the Slotline

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Migliozzi, M.
  • Publikace: IEEE Transactions on Microwave Theory and Techniques. 1998, 46(4), 378-386. ISSN 0018-9480.
  • Rok: 1998

Analysis of Planar Microwave n-Ports

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Workshop 97. Praha: České vysoké učení technické v Praze, 1997. pp. 899-900.
  • Rok: 1997

Solution Completness of the Slotline Dispersion Equation

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Migliozzi, M.
  • Publikace: Radioelektronika '97. Bratislava: STU v Bratislave, 1997. pp. 272-275. ISBN 80-227-0943-3.
  • Rok: 1997

Upper Cut-off Frequency of the Bound Wave and New Leaky Wave on the Slotline

  • Autoři: Zehentner, J., prof. Ing. Jan Macháč, DrSc., Migliozzi, M.
  • Publikace: 1997 IEEE-MTT-S International Microwave Symposium Digest. Piscataway: IEEE, 1997. pp. 487-490. ISSN 0149-645X.
  • Rok: 1997

26th European Microwave Conference: a Technical Preview

Analysis of Slotline Discontinuities and Resonators

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Workshop 96. Praha: České vysoké učení technické v Praze, 1996. pp. 761-762.
  • Rok: 1996

Electromagnetic Field Simulation of the Slotline-Based Planar Circuits

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: 2nd Japan-Central Europe Joint Workshop on Modelling of Materials and Combustion. Budapest: Technical University, 1996.
  • Rok: 1996

Leakage Effects of Dominant and Higher Order Modes on Slotline

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: 26th European Microwave Conference. London: Nexus Media Limited, 1996. pp. 880-884.
  • Rok: 1996

Scattering Matrix of Planar Microwave Multiport

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Radioelektronika '96. Brno: VUT v Brně, 1996. pp. 246-249. ISBN 80-214-0617-8.
  • Rok: 1996

Utilizable Frequency Band and Leaky Wave Phenomenon of the Slotline

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: XIth International Microwave Conference - MIKON '96. Warsaw: Telecommunication Research Institute, 1996. pp. 193-197.
  • Rok: 1996

Application of Slot Lines in Uniplanar Circuits

Calculation of a Complex Resonant' Frequency of the Slot Line Resonator

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Menzel, W.
  • Publikace: Advanced Methods in the Theory of Electrical Engineering. Plzeň: Západočeská universita, 1995. pp. 23-26.
  • Rok: 1995

Complex Resonaut Frequency of Short-Circuited Slot Line Resonator

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Menzel, W.
  • Publikace: 40. Internationales Wissenschaftliches Kolloquium. Gehren: Technische Universität, 1995. pp. 255-259. ISSN 0943-7207.
  • Rok: 1995

Leaky Waves on a Slot Line

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: 1995 URSI Electromagnetic Theory Symposium. St. Petersburg: Saint-Petersburg State Technical University, 1995. pp. 761-763.
  • Rok: 1995

Load Impedances of Complex Slotline Terminations

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Menzel, W.
  • Publikace: 25th EuMC 1995 Conference Proceedings. Kent: Nexus House, 1995. pp. 610-614. ISBN 1-899919-15-5.
  • Rok: 1995

Open-end Termination of a Slot Line

Properties of Slot Line at High Frequencies

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Workshop 95. Praha: České vysoké učení technické v Praze, 1995. pp. 595-596.
  • Rok: 1995

Short and Open Circuited Slot Time

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J., Menzel, W.
  • Publikace: 1995 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference Proceedings. Piscataway: IEEE, 1995. p. 856-861. ISBN 0-7803-2674-1.
  • Rok: 1995

Shunt Post Loaded Waveguide Junctions and Their Application to a Novell Type of Bandpass Filter

Analysis and Design of New Class Waveguide Filters with Suppresed Higher-order Passbands

  • Autoři: prof. Ing. Jan Macháč, DrSc., Menzel, W.
  • Publikace: 2nd Japanese-Czech-Slovak Joint Seminar on Applied Electromagnetics in Materials. Kyoto: Doshisha University, 1994. pp. 125-129. ISBN 963-04-7799-8.
  • Rok: 1994

Analysis of Uniplanar Waveguiding Structures

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: CTU Seminar 94. Praha: České vysoké učení technické v Praze, 1994. pp. 203-204.
  • Rok: 1994

Excitation of Leaky Waves by Slot-line

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Scientific Conference with International Participation. Košice: TU Košice, 1994. pp. 191-196.
  • Rok: 1994

Waveguide Filters Suppressing Higher-order Passbands

E-plane Microstrip-to-waveguide Transition

Oscillator Analysis with Respect to Higher Harmonics

Přenosové vlastnosti štěrbinového vedení

  • Autoři: prof. Ing. Jan Macháč, DrSc., Zehentner, J.
  • Publikace: Moderní metody teoretické elektrotechniky. Plzeň: ZČU FE, katedra teoretické elektrotechniky, 1993. pp. 83-90.
  • Rok: 1993

Waveguide Bandpass Filters with Attenation of Higher-order Passbands

  • Autoři: Menzel, W., prof. Ing. Jan Macháč, DrSc.,
  • Publikace: 23rd European Microwave Conference. Madrid: Reed Exhibition Company, 1993. pp. 606-607. ISBN 0-94682123-2.
  • Rok: 1993

Analysis of Discontinuities in Wave-guiding Structures by MAB Method

  • Autoři: prof. Ing. Jan Macháč, DrSc., Menzel, W.
  • Publikace: IEE Proceedings - Microwaves Antennas and Propagation. 1992, 139(4), 351-357. ISSN 1350-2417.
  • Rok: 1992

Analysis of Discontinuities in Wave-Guiding Structures by MAB Method

  • Autoři: prof. Ing. Jan Macháč, DrSc.,
  • Publikace: IEE Proceedings - Microwaves Antennas and Propagation. 1992, 139(4), 351-357. ISSN 1350-2417.
  • Rok: 1992

Static Model of DH Laser

Za stránku zodpovídá: Ing. Mgr. Radovan Suk