Lidé

doc. Ing. Milan Polívka, Ph.D.

Proděkan pro doktorské studium a výzkum

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.

Harmonic Balance/Full-Wave Analysis of Wearable Harmonic Transponder for IoT Applications

  • DOI: 10.1109/TAP.2021.3111226
  • Odkaz: https://doi.org/10.1109/TAP.2021.3111226
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents a novel design of a compact wearable harmonic transponder with double-plane symmetry, composed of a dual-band patch-type antenna loaded by an HSMS-2820 Schottky diode, operated as a proof-of-concept at ISM UHF 869 MHz and 1 734 MHz frequencies. The antenna is analyzed and optimized for a minimum ground plate size by means of the CST Microwave Studio electromagnetic simulator, and its reflection coefficient is incorporated into the equivalent circuit model for a combined harmonic balance and full-wave analysis using the AWR Microwave Office commercial simulator. The transponder performance, including the complex input impedance matching and conversion loss (CL) between the fundamental and second harmonic frequencies on the diode, was evaluated both in free space and when attached to a human muscle phantom. The total harmonic transponder CL, including diode CL, antenna transponder gains, and impedance mismatching, is 6.2 dB for an excitation power of −25 dBm at the antenna–diode interface. The measured reading distances are 9.0 m and 8.8 m for EIRP = 20 dBm when the transponder is placed in free space and on the human body, respectively. As a means of machine-to-person communication, the transponder is suitable for Internet-of-Things concept, e.g., for the identification of pedestrians in traffic, i.e., in a complex environment with unwanted radiation clutter and multipath fading.

Wearable Harmonic Transponder for IoT Applications

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents a novel compact wearable harmonic transponder, composed of a dual-band patch-type antenna loaded by an HSMS-2820 Schottky diode, operated at 869 MHz and 1 734 MHz frequencies. The antenna itself is optimized for a minimum ground plate size. The transponder performance was evaluated both in free space and when attached to a human muscle phantom. The total harmonic transponder conversion loss is 6.2 dB for an excitation power of −25 dBm at the antenna–diode interface, outperforming state-of-the art solutions. The measured reading distances are 9.0 m and 8.8 m for EIRP = 20 dBm when the transponder is placed in free space and on the human body, respectively. As a means of machine-to-person communication, the transponder is suitable for Internet-of-Things concept.

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.

The proposal strategy to increase the quality and inclusion in education, its internationalization and modernization of administrative processes for The National Technical University of Ukra

  • Pracoviště: Katedra ekonomiky, manažerství a humanitních věd, Katedra elektromagnetického pole, Katedra mikroelektroniky
  • Anotace:
    The present proposal was developed in the frame of the project Strengthening capacities of the National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” in the field of quality and inclusion in education, internationalization and support of cooperation supported by the project of the Ministry of Foreign Affairs of the Czech Republic “Strengthening the capacity of public universities in developing countries”. It is focused on the development of a conceptual strategy and the transfer of Czech know-how in the field of quality and inclusion of the educational process, its management and internationalization.

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.

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.

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.

Reliability Improvement of RF Identification of Shadowed People in Building Corridors Using Space Diversity

  • DOI: 10.13164/re.2018.0762
  • Odkaz: https://doi.org/10.13164/re.2018.0762
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper deals with the investigation of space diversity techniques for elimination of signal fading and consequently extension of coverage area in applications of RF identification of shadowed people in a building corridor. Several measurement scenarios were evaluated. They comprised up to four wearable tags placed at different positions on a human body with one or two reader antennas, including shadowing by a small crowd of people. It was shown that the achieved corresponding SIMO mode diversity gain accounted for ca. 1 dB at the overall improvement in the trace coverage amounted to ca. 5%. On the other hand, the MIMO mode diversity configuration brought an improvement of up to 10% and enabled to cover more than 50% of the identification area, including the scenario where shadowing by a small crowd of people was present.

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.

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.

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.

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.

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.

On-body semi-electrically-small tag antenna for ultra high frequency radio-frequency identification platform-tolerant applications

  • DOI: 10.1049/iet-map.2015.0398
  • Odkaz: https://doi.org/10.1049/iet-map.2015.0398
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this study, the authors proposed the impedance-flexible on-body semi-electrically-small tag antenna for the European ultra-high frequency radio-frequency identification (UHF RFID) frequency band. The radiator is based on differentially-fed coupled shorted-patches and vertical folding techniques, using a loop excitation. The proposed excitation methods enable the input impedance to be tuned to the complex impedance of typical UHF RFID chips as well as to 50 Ω impedance. In addition, the virtual electric short applied inside the structure simplifies the topology and manufacture. The antenna dimensions are 40 × 50 × 3 mm3 (0.12 × 0.14 × 0.01 λ 0) and represent the electrical size ka = 0.58 at 866 MHz. The total efficiency measured in open space exceeds 60%. In case that the antenna is situated on a human phantom, it accounts for 50%. Accordingly, the antenna provides the read range of 5.6 m (in open space) and 5.1 m (when located on human chest).

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.

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

Matching Technique for an On-Body Low-Profile Coupled-Patches UHF RFID Tag and for Sensor Antennas

  • DOI: 10.1109/TAP.2015.2403399
  • Odkaz: https://doi.org/10.1109/TAP.2015.2403399
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper introduces a novel impedance matching technique for extremely low-profile on-body UHF RFID tag antennas based on coupled shorted-patch antennas. The approach employs a novel arrangement of comb-notches perpendicular to the central radiation slot that excites the close higher order mode that affects the field distribution of the fundamental mode and sets the input impedance to the required complex values of UHF RFID chips over the range of 5 to 50 for the real part and 100 to 200 for the imaginary part, or directly to 50 impedance. A set of parametric studies shows the flexibility of the proposed technique for achieving complex input impedances. To verify the proposed technique, we have developed and measured two antenna samples of relative size 0.3 × 0.17 × 0.0022 λ0. A first antenna is matched to 50 , and is intended to be used as an on-body antenna sensor for mapping the received signal strength in applications of the European UHF RFID band. The second antenna operates as an RFID tag antenna with input impedance Zin = 22 + j195, and reaches a read range of 7.3 m.

Stepped Impedance Coupled-Patches Tag Antenna for Platform-Tolerant UHF RFID Applications

  • DOI: 10.1109/TAP.2015.2447034
  • Odkaz: https://doi.org/10.1109/TAP.2015.2447034
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    We introduce a low-profile platform-tolerant UHF RFID tag antenna composed of a pair of three-step impedance sections of shorted-patches coupled by a slot, which is differentially fed by an RFID chip. Its input impedance is analytically investigated using transmission line modeling. A further set of parametric studies using electromagnetic simulation shows good flexibility for achieving the required complex input impedance for typical UHF RFID chips. The selected antenna topology has been manufactured and measured, and good agreement with the analytical values has been found.

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.

Illustration of the Impedance Behaviour of Extremely Low Profile Coupled Shorted-Patches Antennas for UHF RFID of People

  • DOI: 10.1155/2014/712790
  • Odkaz: https://doi.org/10.1155/2014/712790
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The recently introduced coupled shorted-patches technique for the design of extremely low-profile UHF RFID tag antennas is used to illustrate the flexibility of selected feeding methods for tuning the antenna input impedance for the complex values required for matching with typical RFID chips. We present parametric studies of the impedance behaviour of dipole-excited and directly excited antennas designed for radiofrequency identification of people in the European UHF frequency band. Our study can significantly facilitate the design of this class of on-body tag antennas.

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.

Small-Size Wearable High-Efficiency TAG Antenna for UHF RFID of People

  • DOI: 10.1155/2014/509768
  • Odkaz: https://doi.org/10.1155/2014/509768
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper introduces a small-size, low-profile wearable radiator based on the coupled patches and vertically folded patches techniques for application as a tag antenna for identification of people in the European UHF RFID band. The electric field distribution comes out dominantly from the central coupling slot, and thus the electric properties of the radiator are almost unaffected by the human body to which the antenna is intended to be attached. Accordingly, with the relative size 0.14 × 0.12 × 0.009 λ0 at 866 MHz (50 × 40 × 3.04 mm3), the antenna exhibits total efficiency better than 50 %, even if it is attached directly to a person.

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.

Closed-Form Expression for Mutual Impedance of the Short Not-Too-Closely Spaced Dipoles with Constant Current Distribution

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Proceedings of the 7th European Conference on Antennas and Propagation (EUCAP 2013). Piscataway: IEEE, 2013. pp. 1082-1085. ISBN 978-88-907018-3-2.
  • Rok: 2013
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Closed-form expression for mutual impedance of not-too-closely spaced short dipoles with constant current distribution is derived analytically using definition integral relation based on a method of electromotive forces (EMF) and approximation of sine and cosine functions by two or three terms of Taylor series expansion. The values given by analytical expressions are compared with the ones calculated numerically and relative error is presented up to the dipole distance of λ0. The derived expressions might be beneficial for evaluation of e.g. input resistance of close but not-too-closely spaced elements in multi-element monopole arrays.

Impedance Properties and Radiation Efficiency of Electrically Small Double and Triple Split-Ring Antennas for UHF RFID Applications

  • DOI: 10.1109/LAWP.2013.2245295
  • Odkaz: https://doi.org/10.1109/LAWP.2013.2245295
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The present paper is targeted at investigation of electrically small planar antennas, formed by double- and triplesplit rings that are intended to serve as tag antennas operated within the European UHF RFID band. An extensive systematic study of possible geometrical configurations demonstrates the range of their achievable input impedances (complex conjugate to typical UHF RFID integrated circuits) in case that both structures electrically decrease below the limit for electrically small antennas, i.e. ka < 0.5. The advantage of triple split ring version over the standard double split ring one consists in reduction in its electrical size and concurrent maintenance of the required range of input impedances and high radiation efficiency. Samples of both structures were manufactured, measured and their electrical properties critically compared.

Novel Low-Profile Foam Dielectric Over the Shoulder Antenna Based On Coupled Patches Technique

  • DOI: 10.1002/mop.27389
  • Odkaz: https://doi.org/10.1002/mop.27389
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents a novel wearable antenna composed of two coupled patches excited by an overlapping folded dipole. In spite of being operated in a relatively low frequency band 380 ÷ 390 MHz, the antenna shows a very low profile and other dimensions are acceptable as well. Besides a very low absorption of the radiated RF power by any nearby human body, it also ensures a very good immunity against influence on antenna parameters. In comparison to commonly used simple conformal monopole antennas, the presented solution provides a double-side radiation pattern and a substantially higher gain. The antenna can be manufactured using very light and twistable foam dielectric and conductive fabric, and can be worn as a strap placed over the shoulder. It is intended to be used together with personal radio communication transceivers operated in the given frequency band.

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.

Parametric Study of the Low-Profile Foam Dielectric Over-the-Shoulder Antenna Based on Coupled Patches Technique

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents a parametric study of the over-the-shoulder foam dielectric antenna based on coupled patches technique for 380 ÷ 390 MHz frequency band. Despite having a very low profile (0.0072 λ0), it shows the satisfactory radiation efficiency and very good immunity from the negative influences of the human body. Influence of the antenna elements to the radiation efficiency, gain, frequency bandwith and impedance matching is evaluated by means of the parametric study.

Precise Measurement Using Coaxial-to-Microstrip Transition Through Radiation Suppression

  • DOI: 10.1109/TMTT.2013.2272380
  • Odkaz: https://doi.org/10.1109/TMTT.2013.2272380
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a study about the radiation problem of coaxial-to-microstrip launchers and suggests their improvement with a novel design. The proposed solution is based on a coaxial-to-microstrip transition enclosed in a parallel-plate transmission line that has its cutoff frequency above the working frequency band of interest. Any radiated field is quickly attenuated because it is propagating inside a subcritical parallel-plate transmission line. The proposed method is extensively analyzed in the CST Microwave Studio and simulation results are verified on fabricated test-fixture by multiple measurements. The proposed solution improves the accuracy and reduces the uncertainty during measurements on microstrip.

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.

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.

Electrically Small Spiral Transmission Line-Connected Triple-Arm Folded Monopole Antenna

  • Autoři: doc. Ing. Milan Polívka, Ph.D., Vrba, D.
  • Publikace: Proceedings of the 6th European Conference on Antennas and Propagation (EUCAP 2012). Piscataway: IEEE, 2012. pp. 2488-2490. ISBN 978-1-4577-0918-0.
  • Rok: 2012
  • DOI: 10.1109/EuCAP.2012.6206122
  • Odkaz: https://doi.org/10.1109/EuCAP.2012.6206122
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    We proposed electrically small spiral transmission line-connected triple-arm monopole antenna of cylindrical geometry with circumscribing sphere of the electrical length ka = 0.44. The diameter of the antenna base is λ 0/10, and the monopole height is λ 0/20. EM simulation and analysis of radiation resistance as a function of number of monopoles is performed. It is shown that factor N2 appropriately takes into account increase of input resistance of parallel short monopoles even for their λ 0/10 distance. A prototype has been designed for frequency 3 GHz with ground plane size 1.4 × 1.4 λ 0 and provides relative bandwidth of 0.83 %, and measured efficiency of 81.7 %. Proposed structure is simple, and might be completely produced in single layer microstrip technology with linear vertical vias, potencially with additional air substrate layer to improve bandwidth as we present here.

Input Resistance of Electrically Short Not-too-Closely Spaced Multi-Element Monopoles with Uniform Current Distribution

  • Autoři: doc. Ing. Milan Polívka, Ph.D., Vrba, D.
  • Publikace: IEEE Antennas and Wireless Propagation Letters. 2012, 11(1), 1592-1595. ISSN 1536-1225.
  • Rok: 2012
  • DOI: 10.1109/LAWP.2012.2235058
  • Odkaz: https://doi.org/10.1109/LAWP.2012.2235058
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, we derive an analytical expression for the mutual resistance of two electrically short not-too-closely spaced dipoles with uniform current distribution based on an induced electromotive forces method. We go on to apply the relations for folded dipoles for an investigation of the input resistance of a short multi-element dipole arrangement. It is shown that the factor ranging from N^1.77 to N^1.97 takes into account the increase in input resistance arising from the mutual coupling of N = {2, 3, 4} dipoles when they are spaced within the range from λ0/20 to λ0/5. Thus, even a larger distance between the dipoles than λ0/20, which is usually considered if the term N2 is used, still leads to a significant improvement in radiation resistance. To verify the proposed concept, we compared the results provided by the EM simulation and by measurements on the prototype of an electrically small, winding-connected three-element monopole antenna, which occupies a cylindrical geometry with the diameter of the base equal to λ0/10 and the monopole height equal to λ0/20. The measured bandwidth for VSWR = 2 corresponds to the quality factor, which is only 2.2 higher than the principal Gustafsson bound for cylindrical geometry with vertical polarization.

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.

Equivalent Circuit Model for Zeroth-Order Resonator Antenna

  • Autoři: Vrba, D., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: ISMOT Proceedings 2011. Praha: FEL ČVUT, 2011. pp. 151-154. ISBN 978-80-01-04887-0.
  • Rok: 2011
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Zeroth-order resonator (ZOR) as one of the applications of negative phase velocity (NPV) transmission line type has been introduced in several applications [1], among others as a structure for reducing antenna dimensions. For preliminary design of ZOR antennas equivalent models for input impedance calculations has been introduced by several authors [2,3]. However, none of them has considered all components really presented in the model and their proper distribution. Except of right/left handed inductive and capacitive components radiation resistance, radiation losses and mutual inductance of shunt inductors have to be properly taken into account. Their proper location in the equivalent model is the substantial factor for achievement of good agreement of simulated and measured results of input impedance

Radiation Efficiency and Q Factor Study of Franklin Antenna Using the Theory of Characteristic Modes

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents the analysis of Franklin antenna by the Theory of Characteristic Modes. Modal radiation efficiencies are calculated and used to obtain the overall radiation efficiency. For each mode also the Q factor is calculated. On these results the influence of distance between arms of the folded part of antenna is demonstrated.

Special Issue towards EuCAP 2012 "Emerging Materials, Methods, and Technologies in Antenna & Propagation"

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This special issue is composed of six extended papers originally published in Proceedings of EuCAP 2010. The common subject matter is the focus on emerging methods and technologies in antennas and propagation. Another selection criterion has been interdisciplinary of the presented research so that the research would preferably be also outside the scope of A&P topic. As a result we may provide you following themes: biomedical microwave and THz imaging, RF and THz identification technologies, statistical and deterministic modeling of electromagnetic wave propagation in indoor environment.

3D Vision of Electromagnetic Fields in Antenna and Microwave Technique

  • DOI: 10.1109/COMITE.2010.5481636
  • Odkaz: https://doi.org/10.1109/COMITE.2010.5481636
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Two approaches, Virtual Reality Modeling Language (VRML) and graphic library OpenGL, are used for active stereoscopic vision of electromagnetic fields surrounding selected antenna or microwave elements. Input data are generated by analytical relations or acquired by electromagnetic field simulators and visualized in the form of vector fields and field lines by active stereoscopy. In case of VRML freeware Quadroview and GeForce 3D Vision package from nVidia is used to acquire stereoscopic vision. In case of OpenGL implementation own stereo browser StereoEMview has been developed. Both approaches require a little bit different initial sources, knowledge of implementation tools and solution procedures. However resulting output is the same. Thus authors can choose which implementation is more suitable for their nature and available sources.

Active UHF Antennas for Demanding RFID Applications

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    One of possible applications of RFID systems concerns identification of goods equipped with TAGs, densely and randomly accommodated in a larger space. This refers e.g. to the identification of many TAGs fixed on clothes in large cartoon boxes. The TAGs can be located very close to each other, mutually coupled, screened, randomly oriented and placed in an environment with a wide range of wave propagation parameters. The presented paper describes one of the possible solutions. The designed identification system is equipped with active reader antennas that enable the illumination and the read-out of the TAGs from many different locations as well as angles, and with a wide range of illuminating power. According to preliminary measurements, such conditions conduce to 100% correct and reliable identification. The designed RFID system is very likely to be able to work well even in more demanding identification tasks.

Collinear Microstrip Patch Antennas

  • Autoři: Holub, A., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Passive Microwave Components and Antennas. Vukovar: In-Teh, 2010. p. 513-532. vol. 1. ISBN 978-953-307-083-4.
  • Rok: 2010
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The chapter deal with the principle of a novel collinear microstrip patch antennas and their analytical analysis by multiport network method.

Comparison of Small 3D Multi-Loop and Micro-Coplanar ZOR Antennas

  • Autoři: Vrba, D., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Proceedings of the 4th European Conference on Antennas and Propagation. Piscataway: IEEE, 2010. p. 1-4. ISBN 978-84-7653-472-4.
  • Rok: 2010
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, we present performance comparison of 3D four-loop antenna (3D-LA) and ZOR (zeroth-order resonator) antenna realized on micro-coplanar waveguide [1]. The purpose of this study is to further develop 3D multi-loop antenna of similar properties as ZOR antenna. Space arrangement of the 3D-LA enables antenna module realization which can be integrated in PCB.

Electrically Small Loop Antenna Surrounded by a "Shell" of Concentric Split Loops

  • Autoři: doc. Ing. Milan Polívka, Ph.D., Holub, A.
  • Publikace: Proceedings of the 4th European Conference on Antennas and Propagation. Piscataway: IEEE, 2010. pp. 1-3. ISBN 978-84-7653-472-4.
  • Rok: 2010
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Electrically small antenna formed by planar loop with a "shell" of three concentric split loops with the relative outer size ka = 0.40 has been designed with complex input impedance Zin ~ 22 + j195 Ω to be used as UHF RFID tag antenna. The "shell" of concentric loops increases the total current path length so that it reaches the length about 1.08 λ0 at 869 MHz. The measured radiation and antenna efficiency is thus improved and reaches the value about 51 and 33 %, respectively.

Electrically Small Loop Surrounded by a "Shell" of Concentric Plit Rings: Principle and Properties

  • Autoři: Holub, A., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Proceedings of 15th Conference on Microwave Techniques COMITE 2010. Brno: VUT v Brně, FEKT, Ústav radioelektroniky, 2010. pp. 27-29. ISBN 978-1-4244-6351-0.
  • Rok: 2010
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper describes a novel electrically small antenna structure and investigates its physical principle and properties. The antenna is formed by small planar loop with a "shell" of three concentric split rings with external electrical dimension ka=0.4. The structure has been designed with complex impedance Zin 22 + j195 to be utilized as UHF RFID tag antenna. The physical principle is explained via the simulated surface current distribution and several parametrical studies.

Extremely Low Profile UHF RFID TAG Antennas for Identification of People

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Three prototypes of the very low-profile TAG antennas for UHF RFID of people were designed, as result of the long-term development. Their performance properties from the wearability point of view were step-by-step improved. The height were decreased from 1.82 to 0.76 mm (0.0022 λ0 at 869 MHz). The weight were decreased from 38 to 10 g. The gain of antennas measured with enclosed human phantom is in the range of 0.6 ÷ 1.6 dBi. Identification range in real conditions in 4 and 2 m wide buildings corridors reaches 7 and 17 m, respectively, with the NXP Semiconductors chip with the sensitivity of -14 dBm.

Horizontal Five-arm folded dipole over metal screening plane for UHF RFID of Dielectric objects

  • DOI: 10.1002/mop.25475
  • Odkaz: https://doi.org/10.1002/mop.25475
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper is concerned with the extremely low-profile foam dielectric five-arm folded dipole antenna which was developed and manufactured. The aforementioned antenna is situated on the metal screening plane and is used for UHF RFID of dielectric objects. It is designed with a complex input impedance Zin = 22 + j195 Ohm at 866 MHz. Its efficiency was evaluated by Wheeler cap method with and without enclosed a human body phantom - it accounts for approx. 40 %, irrespective of whether the phantom is enclosed or not. The preliminary test of the identification range in buildings corridor was performed. The identification range reaches as far as 15.8 m.

Two Novel Extremely Low-Profile Slot-Coupled Two-Element Patch Antennas for UHF RFID of People

  • DOI: 10.1002/mop.24894
  • Odkaz: https://doi.org/10.1002/mop.24894
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Novel type of extremely low-profile low-dielectric constant substrate antenna, based on two-element slot-coupled shorted-patch structure for UHF RFID applications has been developed. We use two different methods for tuning the complex input impedance - dipole excitation and direct excitation with tuning slots. Both credit card-sized antennas exhibit the antenna efficiency better than approx. 50 %, irrespective of whether they are placed in free space or enclosed to either metallic or human body.

Efficiency Treatment of Two CLosely Spaced Metal Sheets by Characteristic Mode Theory

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Radiation efficiency of two closely spaced metal sheets is studied by using the theory of characteristic modes (TCM). All modes of the structure in given frequency range are identified and their radiation efficiency is calculated. The overall radiation efficiency is computed as a combination of modal efficiencies. Radiation efficiency of the structure is studied for different distances between the sheets and is compared with results acquired by MoM software IE3D.

Electrically Small Meanderly Folded Patch Antennas

  • Autoři: Holub, A., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: EuCAP 2009 - 3rd European Conference on Antennas and Propagation. New York: IEEE, 2009. pp. 2448-2451. ISBN 978-1-4244-4753-4.
  • Rok: 2009
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper introduces a novel small antenna structures - meanderly folded patch antennas - and discusses performance properties of several miniaturized versions. All antenna versions operate on the basic mode TM010. The influence of the number of meanders, size of the antenna, quality factor Q, frequency bandwidth BW and directivity is discussed.

Microwave Radar Sensors for Active Defense Systems

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Modern anti-armor missiles represent enormous threat for any military vehicle. Simple hand-held missiles are able to penetrate 300 mm, more sophisticated missiles up to 1000 mm of the best steel armors. Active defense methods seem to be promising ways how to face this problem. Systems of active defense are based on sensors able to detect and measure approaching threat missile and generate signals that activate a suitable counter-measure. The paper describes several different designed radar sensors tested in active defense configurations. This concerns narrowband sector sensor, "microwave curtain" and a new wideband sensor with a distance measurement capability. All practical tests were performed using real missiles at army shooting ranges.

Novel Dual-loop antenna Placed over Patch Array Surface for UHF RFID of Dielectric and Metallic Objects

  • DOI: 10.1002/mop.24169
  • Odkaz: https://doi.org/10.1002/mop.24169
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Novel electrically small low-profile dual-loop antenna over artificial-like surface, formed by four-element sub-wavelength patch array printed on grounded dielectric slab used for shielding in UHF RFID applications, has been developed. The badge-sized antenna exhibits the gain of about 1 dBi and antenna efficiency amounting to approx. 30 - 40 % whether it is placed in free space or enclosed to dielectric/metallic objects.

Radiation Efficiency Improvement of Zeroth-Order Resonator Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The radiation as well as antenna efficiency of very thin profile zeroth-order resonator (ZOR) antenna, implemented in negative phase velocity (NPV) microstrip transmission line (TL) structure, has been solved by the method of moment simulator IE3D. The radiation is investigated using individual portions of the ZOR antenna that shows significant values of the surface current density. Dominantly radiating parts have been identified, geometrically emphasized by means of the increase in the antenna height over the ground plane from 1/105 to 1/8 λ0. The measured parameters of the improved antenna prototype have been enhanced so they reached the following values (compared to original ones): gain 5.0 dBi (-3.0 dBi), antenna efficiency 97.7 % (9.5 %).

Radiation Equivalent Circuit Model of Zeroth-Order Resonator Antenna

  • Autoři: Vrba, D., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: European Microwave Week 2009 - Conference Proceedings. London: Horizon House Publications, 2009. pp. 1275-1278. ISBN 978-1-4244-4748-0.
  • Rok: 2009
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Radiation equivalent circuit model (RECM) of zerothorder resonator (ZOR) antenna implemented in microstrip line technology comprising radiation resistance and mutual inductance of shunt inductors in each element cell is investigated. The antenna input impedance acquired from RECM is compared with measured data and it is found that presented model provides a good first-order approximation for initial design of presented ZOR type antenna.

Shielded Micro-Coplanar CRLH TL Zeroth-Order Resonator Antenna: Critical Performance Evaluation

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The attention of this paper is focused on the four unit cell zeroth-order resonator antenna (ZORA), manufactured on a shielded micro-coplanar composite right/left-handed (CRLH) transmission line structure. The antenna was designed to achieve a broadside patch-type radiation pattern. The dimensions of the antenna element follow: 15.6 x 9.35 x 3.1 mm (i.e. 0.27 x 0.16 x 0.05 λ0 at the measured zeroth-order resonance f0 = 5.14 GHz) with the shielded plane of the size of 60 x 40 mm (approx. 1.0 x 0.7 λ0). The measured gain and the antenna efficiency are equal to 4.6 dBi and 48 %, respectively. The performance of the proposed ZORA is subject to critical evaluation based on the comparison with the reference quarter-wavelength patch antenna (QWPA) that has the same dimensions.

UHF RF Identification Distance in Indoor Areas

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    UHF RFID read range tests have been performed with a novel electrically small low-profile TAG antenna equipped with an artificial-like surfaces providing very good immunity against the influence of a near human body. The RFID system equipped with this antenna has been tested for the detection of a person in indoor and outdoor areas within 869 MHz band and reached read range up to 9 m.

UHF RF Identification of People in Indoor and Open Areas

  • DOI: 10.1109/TMTT.2009.2017305
  • Odkaz: https://doi.org/10.1109/TMTT.2009.2017305
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    UHF RFID read range tests have been performed with a novel electrically small low-profile TAG antenna equipped with artificial-like surfaces providing very good immunity against the influence of a near human body. The RFID system equipped with this antenna has been tested for the detection of a person in indoor and outdoor areas within 869 MHz band and reached read range up to 9 and 16 m, respectively.

UHF RFID of People

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The book chapter is focused on radiofrequency identification of people: review, design and measurement of low profile antenna types suitable for RFID of persons; modeling and measurement of received signal level both in indoor and open environments, shadowing and corresponding signal fading; optimization of identification task geometry; read range identification tests and reliability identification tests both in indoor and open spaces including one person and a group of persons moving from slow to fast.

Vertically Meander-folded, Shorted-patch Antennas

  • Autoři: Holub, A., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Microwave and Optical Technology Letters. 2009, 51(12), 2938-2942. ISSN 0895-2477.
  • Rok: 2009
  • DOI: 10.1002/mop.24790
  • Odkaz: https://doi.org/10.1002/mop.24790
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this study, a novel miniaturized microstrip patch antenna based on meander-folded, shorted-patch (SP) structure is introduced. The technique enables a decrease of the original quarter-wavelength patch length approximately by the factor 1/N, where N is the number of the vertically placed patch plates above the ground plane. The antenna operational principle is explained with the help of E-field distribution and can be interpreted as SP with vertically meander-folded cavity. Further modification of the top patch plate to ensure symmetrical radiation pattern is proposed.

Zeroth Order Resonator Antenna Realized on Shielded Micro Coplanar Transmission Line

  • Autoři: Vrba, D., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: EuCAP 2009 - 3rd European Conference on Antennas and Propagation. New York: IEEE, 2009. pp. 3066-3069. ISBN 978-1-4244-4753-4.
  • Rok: 2009
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    MTM ZOR antenna realized on micro-coplanar transmission line were designed to achieve broadside patch-type radiation pattern. The antenna footprint size without ground plane is 1/4 λ0 x 1/6 λ0, the total height is 1/20λ0. Simulated radiation efficiency and gain are 69% and 1.61 dBi, respectively at design frequency f=4.95 GHz.

A Novel Microstrip Patch Antenna Miniaturization Technique: A Meanderly Folded Shorted-Patch Antenna

  • Autoři: Holub, A., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. p. 39-42. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    novel microstrip patch antenna miniaturization technique based on multilayer meanderly folded shorted-patch structure is introduced. The technique enables a decrease of the original shorted (quarter-wavelength) patch dimension by the factor 1/N where N is a number of vertically placed patch plates above the ground plane while maintaining a quarter wavelength resonant length. The antenna operational principle is explained via both E-field distribution inside the antenna structure and the surface current distribution on the conductive parts of the antenna.

Effective Segmentation in Multiport Network Model Method for Analysis of Planar Antennas with thin Slots

  • Autoři: Holub, A., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: ISAP 2008 Proceedings. Tokyo: IEICE, Institute of Electronics, Information and Communication Engineers, 2008. ISBN 978-986-84787-0-1.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper a novel approach to Multiport Network Model (MNM) method for electromagnetic analysis of planar structures with thin slots is presented. Real slots with certain width are incorporated in the model as a slot with null width by leaving their ports disconnected during process of segmentation. These ports are connected to the Edge Admittance Networks (EANs). The advantage of this approach is the compact and more efficient computational algorithm.

Efficiency Treatment of Composite Right/Left-Handed TL Zeroth-Order Resonator Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Antenna efficiency of zeroth-order resonator (ZOR) antenna implemented in composite right/left-handed transmission line (CRLH TL) microstrip structure is treated by method of moment simulator IE3D. Radiation is investigated from individual portions of the antenna structure according to calculated amplitude of surface current density. Dominantly radiating regions are identified, geometrically emphasized, nad efficiency improved version of CRLH ZOR antenna is designed, realized, measured and compared with initial design. Improvement of simulation antenna efficiency from 10 to 75 % and 4x increased measured gain at design ZOR frequency has been found.

Efficiency Treatment of Two Closely Spaced Dipoles by Characteristic Mode Theory

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The two closely spaced dipoles exhibit frequency narrow deep decline of radiation efficiency. This phenomenon istreated by theory of characteristic modes (TCM). Modal currents excited close to the resonant frequencies aredetermined, antenna and transmission line modes are identified, comparison of their relative amplitudes, and corresponding modal fields and radiated power are provided. Radiation efficiency calculated from TCM approach is compared with the results acquired by MoM software IE3D.

Electrically Small, Multiband, and Enhanced Directivity Antennas for Communication Terminals

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: 18th International Travelling Summer School on Microwave and Lightwaves - Proceedings. Brno: VUT v Brně, FEKT, Ústav radioelektroniky, 2008. pp. 364-379.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper deals with the modern electrically small, multiband and gain enhanced antennas for communication terminals. Typical configurations are presented, original contribution of the author is added as well.

Improvement of the Radiation Efficiency of the Metamaterial Zero-Order Resonator Antenna

  • Autoři: Vrba, D., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. p. 249-252. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper a technique for improvement of radiation efficiency of metamaterial zero order antenna based on increasing of vertical antenna height is presented. Result of this method is here demonstrated by comparison of the two microstrip line implementation of the zero order resonator (ZOR) antennas with different height of upper conductor above ground plane. Improved ZOR antenna exhibits 75% efficiency, while the reference antenna efficiency is 10% only.

Improving the Radiation Efficiency of the Metamaterial Zero-Order Resonator Antenna

  • Autoři: Vrba, D., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Scientific Seminars - Proceedings from year 2007/2008, Volume VII, Part of the Project GACR 102/08/H018. Praha: IEEE Czechoslovakia Section, 2008. p. 78-81. ISBN 80-86582-22-1.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper a technique for improvement of radiation efficiency of metamaterial zero order antenna based on increasing of vertical antenna height is presented. Result of this method is here demonstrated by comparison of the two microstrip line implementation of the zero order resonator (ZOR) antennas with different height of upper conductor above ground plane. Improved ZOR antenna exhibits 75% efficiency, while the reference antenna efficiency is 10% only.

Multiple-Arm Folded Monopole Antenna Operating Extremely Close to a Conductive Plane

  • DOI: 10.1109/COMITE.2008.4569894
  • Odkaz: https://doi.org/10.1109/COMITE.2008.4569894
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Horizontal multiple-arm folded monopole antenna operating extremely close to a conductive plane (0.003 lambda) band has designed, realized and measured. In spite of the extremely low relative antenna height above the conductive plane intended to be used as a shielding of human body or metallic objects antenna antenna has satisfactory radiation efficiency and gain over 1 dBi. Antenna in dipole arrangement is intended to be used for RFID at 869 MHz frequency.

Novel Metamaterial Cell-Based Resonator Antenna with Broadside Radiation Pattern

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A novel electrically small low-profile zero-order resonator antenna in micro-coplanar TL with both-side broadside radiation pattern has been developed. Its measured radiation efficiency and gain are 54 % and 2.1 dBi, respectively. The antenna is able to provide approx. 45% size reduction compared to the patch antenna of the same resonant frequency.

Parametric Study of the Novel UHF RFID Dual-loop Antenna

  • DOI: 10.1080/09205071.2013.868327
  • Odkaz: https://doi.org/10.1080/09205071.2013.868327
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Novel electricaly small low-profile dual-loop antenna over artificial-like surface formed by four-element subwavelength patch array printed on grounded dielectric slab used for shielding in UHF RFID applications has been developed. The parametric study of the antenna has been performed. The antenna exhibit the gain about 1 dBi without significant affecting by the presence of a dielectric objects placed in the close vicinity of the antenna.

Radar Sensor for Detection of Anti-Armour Missiles

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The anti-armour missiles represent one of the biggest threads for any military vehicle, both in a standard combat or e.g. during UN humanitarian as well as peacekeeping operations. Millions of extremely dangerous missiles, able to break-through even tank armour-plates, are widely spread even in the world's most dangerous hot spots and geostrategic areas. Standard lighter vehicles and helicopters alike do not have, by themselves, any chance against them. As a result, the possibly more efficient methods of defense against them are under scrutiny and are subject to a continuous development. Active defense methods are based on a detection of the thread missiles and activation of an efficient counter-measure. The presented paper describes parameters of two most dangerous missiles and calculates parameters decisive for their detection in microwave frequency range. The practical measurements verify and confirm the calculated detection parameters.

Radiation Efficiency of the Metamaterial Zero-order Resonator Antenna

  • Autoři: Vrba, D., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: PIERS - Progress In Electromagnetics Research Symposium - Draft Proceedings. Cambridge, MA: The Electromagnetics Academy, 2008. p. 482-485. ISSN 1559-9450. ISBN 978-1-934142-06-6.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper a simulated and realized antenna and radiation efficiencies for several types are presented. Radiation pattern from individual parts and from the whole structured are compared and discussed. From results of radiation pattern and from current density distribution can be determine regions of structure which radiates significantly.

The Design of the Multiple-Arm Folded Dipole Antenna Operating Closely Spaced to a PEC

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The planar multiple-arm folded dipoles operating closely spaced to a perfect electric conductor (PEC) plane were studied in order to find the approach for the design of the low profile dipole type antenna with a metallic shielding applicable for the radiofrequency identification (RFID) within 2.4 GHz band. The effect of applied multiple-arm folded dipole technique on the input resistance, radiation and antenna efficiency of treated dipole configurations is explored. The antenna prototype in the monopole configuration has been realized and measured to verify its performance properties.

Application of MNM on Collinear Microstrip Patch Antenna

  • Autoři: Holub, A., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Proceeding - 2007 IEEE Antennas and Propagation Society International Symposium. Piscataway: IEEE, 2007. pp. 61-64. ISBN 978-1-4244-0877-1.
  • Rok: 2007
  • DOI: 10.1109/APS.2007.4395430
  • Odkaz: https://doi.org/10.1109/APS.2007.4395430
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents the Multiport Network Model of Collinear Microstrip Patch Antenna excited by mode TM03. The teoretical results are compared with the Method of Moment based IE3D results. For the accurate matching of results ot the both methods the radiating equivalent admittance network of the inner slot has been included.

Application of the UHF RFID System for the Identification of Sportsmen in Mass Races

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A modification of a standard UHF RFID system for identification of sportsmen during mass races was proposed, realized and verified. The performed mathematical simulations and measurements indicated the system components that are decisive for correct identification, i.e. primarily, both the reader and the transponder (TAG) antennas, their radiation patterns, tilt and efficiency. The optimized RFID system was tested in a standard outdoor operation with several configurations of sportsmen moving with different speeds from approx. 4 km/h up to 15 km/h. The obtained final results show 100 % identification reliability.

Branched F-type Antenna Array

  • Autoři: Holub, A., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Proceedings of 17th International Conference Radioelektronika 2007. Brno: FEKT VUT v Brně, 2007. pp. 271-274. ISBN 978-1-4244-0821-4.
  • Rok: 2007
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents new ideas of improvement of planar F-type antennas by parallel array approach. This solution exhibits further gain enhancement compared to classical F-antenna with omnidirectional radiation. The antenna array is obtained by parallel line up of radiating elements. It causes radiation in two directions (forward and backward), which is not useful for practical usage. The reflection plane is applied to prevent backward radiation and to enhance a directivity. The arrays of 1, 2 and 3 elements are presented and compared. The advantage of this type of antenna is its relatively simple implementation.

Collinear and Coparallel Principles in Antenna Design

  • Autoři: doc. Ing. Milan Polívka, Ph.D., Holub, A.
  • Publikace: PIERS 2007 Prague - Proceeding of Progress In Electromagnetics Research Symposium. Cambridge, MA: The Electromagnetics Academy, 2007. pp. 284-288. ISSN 1559-9450. ISBN 978-1-934142-02-8.
  • Rok: 2007
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper summarizes collinear principle (CollP) used for the design of enhanced directivity collinear arrays (CollAr) first. Various types of collinear arrays starting from historical wire design introduced by Franklin, going through coaxial collinear arrays as far as to the most recent CollAr implemented in microstrip line and patch technology are mentioned. Further supplementary principle of parallel line up arrangement of in-phase current sources to form coparallel array (CopAr) in presented. Two examples of CopAr based on planar extension of collinear microstrip patch antenna (PCoMPA) and branched F-type antenna are described in more details.

Design of Dualband Quarter-Wavelength Patch Antenna by Tuning Its Natural Resonances

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Proceeding - 2007 IEEE Antennas and Propagation Society International Symposium. Piscataway: IEEE, 2007. p. 996-999. ISBN 978-1-4244-0877-1.
  • Rok: 2007
  • DOI: 10.1109/APS.2007.4395664
  • Odkaz: https://doi.org/10.1109/APS.2007.4395664
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper deal with the design of quarter-wavelength patch antenna that uses its natural basic and higher order modes resonances. Proper tuning of both operating frequencies is achieved by introducing of I and L shaped notches into the patch motif and optimization of patch and notch sizes.

Dualband Wearable UHF RFID Antenna

  • DOI: 10.1049/ic.2007.1546
  • Odkaz: https://doi.org/10.1049/ic.2007.1546
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Based on a system study of the ability to use a commercial RFID system operating in 869 MHz band for the identification of moving sportsmen [1], TAG antennas has been recognized as one of the most sensitive component that affect the proper function of the whole system, especially in case when TAG antenna has to operate in the close vicinity of human body. Single and dual-band weareable patch antenna to cover European (869.5 - 869.7 MHz) and US (902 - 930 MHz) RFID bands that are not affected by the presence of human body has been designed, manufactured and measured. The specifics of the design are complex conjugate input impedance to the impedance of the chip used, application of technique to extent the operating band, using of the foam dielectric and conductive cloth. The properties of developed TAG antennas has been compared with meander dipole and patch test antennas in free space as well as in the close vicinity to the human phantom.

Electrically Shortened Wire RFID Antennas Closely Spaced TO a PEC

  • Autoři: doc. Ing. Milan Polívka, Ph.D., Ambemou, E.
  • Publikace: Proceeding of the 2nd European Conference on Antennas and Propagation. Stevenage, Herts: The Institution of Engineering and Technology (IET), 2007. ISBN 978-0-86341-842-6.
  • Rok: 2007
  • DOI: 10.1049/ic.2007.1544
  • Odkaz: https://doi.org/10.1049/ic.2007.1544
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper deal with the configurations of wire RFID antennas with complex input impedance operating closely spaced to a PEC plane using folded and multiple-arm technique and influence of these techniques for increase of radiation resistance and efficiency.

Enhanced Gain Microstrip Patches Operating on Higher-Order Modes

  • Autoři: doc. Ing. Milan Polívka, Ph.D., Holub, A.
  • Publikace: International Journal of Microwave Science and Technology. 2007, 2007(ID 46350), 1-5. ISSN 1687-5826.
  • Rok: 2007
  • DOI: 10.1155/2007/46350
  • Odkaz: https://doi.org/10.1155/2007/46350
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Novel topologies of rectangular microstrip patches providing broadside radiated one point fed radiators with enhanced gain are compared. The principle of the gain enhancement is based on an extension of a source area. Dominant in-phase current distribution on the patch is maintained by using higher order mode and geometrical modification of the patch topology. That is achieved by introducing suitable perturbation elements in the shape of slots and notches. Two principal patch topologies operating on TM21 and TM03 modes are described. A comparison of simulated and measured properties of realized prototypes at 10 GHz band are presented. The results show that gain 12.3 dBi of single patch can be reached.

Microstrip Patch Antennas with Specific Properties: Multi-band, Miniaturized, and Gain Enhanced

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper deals with the microstrip patch antennas with specific properties that are based on re-arrangement of current densities on their surface by means of geometrical modifications. Selected types of multi-band patches with edge perturbation elements, electrically miniature fractal and gain enhanced collinear patches are presented. Description of the physical behavior via surface current distribution, as well as used design approaches are done.

Multiport Network Modeling of a Complex Canonicaly Shaped Patch Antenna

  • Autoři: Holub, A., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Proceeding of the 2nd European Conference on Antennas and Propagation. Stevenage, Herts: The Institution of Engineering and Technology (IET), 2007. ISBN 978-0-86341-842-6.
  • Rok: 2007
  • DOI: 10.1049/ic.2007.1191
  • Odkaz: https://doi.org/10.1049/ic.2007.1191
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper an implementation of MNM on a complex structure based on canonicaly shaped elements is presented. A MNM may be considered as an extension of the cavity model. We consider a large number of ports on the edges of the planar elements and via this ports the canonicaly shaped elements can be connected to the more complex structures. So called segmentation method is used to approximate the shape of the antenna. The field outside the patch and mutual coupling between edges are incorporated by adding equivalent edge admittance networks (EAN'S) and a mutual coupling network.

The Optimization of the RFID System for the Identification of Sportsmen in Mass Races

  • DOI: 10.1109/EUMC.2007.4405296
  • Odkaz: https://doi.org/10.1109/EUMC.2007.4405296
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper deal with the optimization of a standard UHF RFID system for usage in an identification of mass race sportsmen. Proposed improvements has been realized and the optimized RFID system has been tested in a standard outdoor operation, the results proved 100% identification reliability.

Analysis and Measurement of the RFID System Adapted for Identification of Moving Objects

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A system study of ability of using a commercially available 869 MHz RFID system for identification of moving objects has been performed. The study has been focused on a power budget of received signal levels and on identification of main signal fadings and their quantification. Two types of TAG antennas have been used. Comparisons of their radiation properties when operated in the close vicinity of the a human body (or a simple phantom of a human body) have been performed. Suitability of their use is discussed. Results of this study provide deeper insight in the given problem and information in which way the system should be improved in order to comply with the intended purposes.

Education in Antennas, Wave Propagation and Microwaves

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper is focused on teaching of "applied microwaves". Attentions is turned to antennas, but the same structure of education process is possible to apply for e.g. radio-wave propagation, microwaves, EMC, and other "electromagnetic topics" in their whole. The structure of the education is based on the appropriate amount of the theory followed by the computer simulations, the theoretical and engineering design and development, the measurement and final evaluation, which acts as the feedback between the initial goals and the final results. Important role of laboratory experiments based on flexible experimental set-ups is introduced and the possibility of distant (internet) laboratory excess is mentioned.

Multiband Patch Antenna with Perturbation Elements Generated by Genetic Algorithm

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper deal with the design of dualband patch antenna with edge perturbation elements in the form of notches. Their size if need shape is modified by genetic algorithm. Perturbation element is generated by random proccess in a grid structure. Symetry and periodicity of perturbation elements is used for tuning radiator for 2.4/5.8 GHz bands.

Planar Version of Collinear Microstrip Patch Antenna

  • Autoři: doc. Ing. Milan Polívka, Ph.D., Holub, A.
  • Publikace: Conference Proceedings - MIKON 2006. Warsaw: Telecommunication Research Institute, 2006. p. 959-962. ISBN 83-906662-7-8.
  • Rok: 2006
  • DOI: 10.1109/MIKON.2006.4345343
  • Odkaz: https://doi.org/10.1109/MIKON.2006.4345343
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents a planar version of collinear microstrip patch antenna that exhibits further gain enhancement compared to collinear microstrip patch antenna due to the lateral extension of in-phase source current area of radiation element. The principle of operation is similar as in case of collinear wire antennas. The basic idea consists in the use of TM0x mode with geometrical perturbation of radiation motif by inner slot(s) and lateral notches introduced in such a way that they eliminate radiation from even half current wavelengths. Detailed principle of an antenna operation explained via vector surface current distribution, determination of initial antenna dimensions and final optimization in planar simulator IE3D are presented. The prototype of the antenna operating in 2.4 GHz ISM band has been realized and measured.

Spiral Notch Perturbation Element Concept for the Design of Multiband Quarterwavelength Patch Antennas

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Quarterwavelenght patch antenna loaded by one to three pairs of spiral notches has been used to reach dual to quadband performance. Physical insight on multiband behavior is done via description of vector surface current distribution at individual resonant frequencies acquired by EM simulator IE3D. The used principle has been verified by measurement on the dualband prototype. The method can been generalized as the use of perturbation elements in the patch motif to excite suitable higher order modes to reach multiband performance of the studied antenna.

10 GHz Broadside Radiated Linearly Polarized Microstrip Patch with Enhanced Gain

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Broadside radiated microstrip patch with enhanced gain has been designed with center frequency of 10 GHz. In order to achieve gain enhancement together with broadside linearly polarized radiation novel technique that uses radiation of surface modified rectangular microstrip patch operating with TM21 mode has been used. Designed radiator has been realized and measured. Gain of 11.5 dBi of single fed patch radiator has been reached. Comparision with properties of a simple rectangular patch operating with basic TM01 mode is also presented.

Collinear Microstrip Patch Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper deal with a novel type of so called collinear types of antennas realized in microstrip antenna technology. Principle of operation is in excitation of TM0x modes of patch antenna where x is odd number that stands for the number of resonant half current wavelength. Perturbation elements in the shape of lateral slots are placed in the structure of the patch in such a way that they eliminate radiation from even half current wavelengths. Resulting (x+1)/2 in-phase source areas ensure broadside radiation. Prototype of the antenna for frequency band 869 MHz has been realized and measured.

Dualband Quartewalength Patch Antenna Loaded by a Pair of Spiral Notches

  • Autoři: Čevela, M., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: The 13th Conference on Microwave Techniques - COMITE 2005. Praha: IEEE Czechoslovakia Section, 2005. pp. 44-47. ISBN 80-86582-16-7.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Dualband quarterwalenght patch antenna loaded by a pair of spiral notches has been studied with the help of planar simulator IE3D. Principle of its dualband behavior has been explained via description of surface current distribution at both resonant frequencies. Simulated and measured results of realized prototype as well as its typical radiation properties are discussed.

Education in Antennas, Wave Propagation and Microwave Techniques

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper is focused on teachnig "applied microwaves". Attention is turned to antennas, wave propagation, microwaves and EMC. The structure of the education based on the theory followed by the computer simulations is described. A mutual cohesion between engineering, design, numerical methods, CAD is mentioned.

Gain Enhancement of Broadside Radiated Microstrip Patch Operating with Higher order Mode

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Radioelektronika 2005 - Conference Proceedings. Brno: VUT v Brně, FEI, Ústav radioelektroniky, 2005. pp. 417-419. ISBN 80-214-2904-6.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Patch radiator with enhanced gain operating with higher order mode TM21 has been designed. Patch is loaded with two T slots introduced in shorter patch edges in order to outbalance current component in the direction of demanded polarization. Patch is thus linearly polarized with broadside radiation. Comparision with gain of simple rectangular patch operating with basic TM01 mode is also presented.

High Dynamic Range Multiplier for Detection and Localization of BPSK WCDMA Signals

  • DOI: 10.1109/EUMC.2005.1608866
  • Odkaz: https://doi.org/10.1109/EUMC.2005.1608866
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A special signal multiplier has been designed and measured. Its main purpose is to remove spreading from BPSK WCDMA signals and to improve their detection and measurement. Extending units based on this multiplier will be tested in existing systems that detect an illegal usage of standard TDMA/FDMA mobile phones in prison buildings and areas.

Microwave Antennas and Circuits Modeling Using Electromagnetic Field Simulator

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Electromagnetic (EM) field simulators have become widely used tool in a design process of microwave circuits and systems. Proper usage of the EM field simulators allows substantial reduction of the design time providing reliable results. In such case the required parameters of the designed circuit can be reached even at the first manufactured prototype in spite of high complexity of the structure. However, EM simulation as a numerical process suffers from systematic and random errors similar to measurement using real equipment. Thus the setting of the EM-field simulator such as frequency range, mesh properties, usage of PEC and PMC walls etc. has to be done with the highest attention and the simulation results have to be always verified using well-established techniques. The aim of the paper is to demonstrate the selected capability of EM-field simulators with a few examples of antenna and circuit modeling. Also an issue of reliability and simulation errors will be discussed.

Microwave System for the Detection and Localization of Mobile Phones in Guarded Buildins

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Novel monitoring system for the detection and localization of mobile phones in large buildings based on a matrix of microwave sensors has been designed and practically employed. Each sensor consists of three RD channels for a separate detection of differenct mobile services. Both time-domain and frequency domain analyses are applied on the RF receiver output signals in order to differentiate individual mobile services. Up to now, microwave systems with approximately 2000 sensors have been installed and successfully operated in 13 prisons in the Czech Republic. The system has been found as one of effient tools for improving security in large highly guarded buildings.

Microwave System for the Detection and Localization of Mobile Phones in Large Buildings

  • DOI: 10.1109/TMTT.2005.848750
  • Odkaz: https://doi.org/10.1109/TMTT.2005.848750
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A novel monitoring system for the detection and localization of mobile (cellular) phones in large buildings based on a matrix of microwave sensors has been designed and practically employed. The system enables detection of all active mobile services and ensures very high immunity against all other radio signals. The designed antennas, system structure and signal processing provide high probability of correct localization of the transmitting mobile phone.

Multiband Behavior of the Rectangular Microstrip Patch Antenna Modified by T-notch Perturbation Elements

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: ICECom 2005 - Conference Proceedings 18th International Conference on Applied Electromagneics and Communications. Dubrovnik: IEEE Croatia Section, 2005. p. 185-188. ISBN 953-6037-44-0.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Multiband behaviour of the rectangular linearly polarized broadside radiated microstrip patch antenna (MPA) modified by one and two stage T-notch shaped perturbation elements has been studied with the help of planar simulator IE3D. Explanation of physical multiband behaviour providing broadside radiation of MPA is done via description of surface current distribution at selected resonance frequencies. Properties of both radiators are discussed. Similarity of 2-stage T-notch perturbation element modification approach of MPA with fractal antenna concept is mentioned.

Planar Five-element Yagi-uda Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper describes a design of planar five-element Yagi-Uda antenna for 2,4 GHz band. The structure has been optimized for a maximum directivity and maximum front-toback ratio by planar simulator IE3D. Special feature of the antenna are reflector formed by ground plane edge and solution of impedance symmetrization and matching. Antenna has been realized and measured. Comparison of simulated and measured data are also presented.

Simulations and Realization of Planar Five-Elements Yagi-UDA Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper presents a comparison of planar Yagi-Uda antenna simulation performed by two different planar simulators. The simulations have been done by planar simulator IE3D that uses integral equation/method of moment (IE/MoM) analysis in frequency domain and by planar simulator CST Microwave Studio that uses method of finite difference time domain analysis (FDTD). Comparisons of simulated and measured data are also presented.

Zobecněný přístup k měření v mikrovlnné oblasti

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Je popsán obecný princip měření jak v časové, tak ve frekvenční oblasti a vzájemné vazby jednotlivých parametrů.

IE3D simulátor a jeho použití pro analýzu a optimalizaci antén a amikrovlnných obvodů

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Počítačové prostředky pro mikrovlnnou techniku. Praha: Česká elektrotechnická společnost, 2004. pp. 30-33.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Příspěvek pojednává o použití simulátoru IE3D pro elektromagnetickou analýzu a optimalizaci antén a mikrovlnných obvodů. Stručně uvádí základní rysy simulátoru, popis použité numerické metody a několik úloh řešených na katedře elektromagnetického pole FEL ČVUT v Praze.

Microwave System for the Detection and Localization of Mobile Phones in Large Highly Guarded Buildings

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Novel monitoring system for the detection and localization of mobile phones in large buildings based on a matrix of microwave sensors has been designed and practically employed. Each sensor consists of three RF channels for a separate detection of different mobile services. Both time-domain and frequency domain analyses are applied on the RF receiver output signals in order to differentiate individual mobile services. Up to now, microwave systems with approximately 2000 sensors have been installed and successfully operated in 13 prisons in the Czech Republic. The system has been designed as one of efficient tools for improving security in large highly guarded buildings.

Návrh a vývoj antén

Optimization of Antennas Using Genetic Algorithm and Classical Optimization Method with Matlab and IE3D

  • Autoři: Drahovzal, M., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Conference Proceedings of Radioelektronika 2004. Bratislava: Slovak University of Technology, 2004. pp. 233-236. ISBN 80-227-2017-8.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Matlab script for the optimization and design of dual-band or generally multi-band planar patch antennas of predefined shapes have been realized based on the combining of genetic algorithms and simplex method. Program IE3D is used to analyze antenna structure in implemented Matlab optimization loop.

Simulace antén a mikrovlnných obvodů

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Modelování antén a mikrovlnných obvodů v 2,5D a 3D elektromagnetických simulátorech ve frekvenční i časové oblasti včetně modální analýzy jsou popsány.

Synthesis of Dualband Broadside Radiated Microstrip Patch Antenna Operating with TM10 and TM21 Modes

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Novel concept for the synthesis of linearly polarized broadside radiated dualbad microstrip patch antenna has been used. Presented novel approach uses basic and suitable higher modes of patch resonator that are modified by appropriate patch surface perturbation so that outbalancing current component in the direction of demanded polarization is dominant at bot design frequencies. This concept is differenct than standard approach that use additional passive resonators in the same metal level as feeded patch or in other layers in so called stacked arrangement of another frequently used concept that modify patch by introducing suitably shaped perturbing elements such as slots and nothes. These snadard approaches has common feature namely that additional basic modes or basic resonances of parasitic parts are excited. Proposed novel approach has been verified on model of dualband 3.5/5.5 GHz microstrip patch antenna.

Synthesis of Planar Antennas with the use of Higher Order Modes Resonances

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The usage of higher order modes for realization of two planar antennas with dualband performance and higher directivity has been studied the help of IE3D planar simulator. 2.4/5 GHz linearly polarized dualband microstrip patch antenna that is designed by novel concept that uses basic TM10 and modified TM21 modes for achieving dualband performance with the demanded linear polarization in both frequency bands has been studied as a first example. 2.45 GHz three half-wavelength slot radiator has been simulated as a second example. Structures of both radiators have been modified in such a way so that broadside radiation has been achieved to be able to use them in an array.

Usage of Higher Order Modes Resonances for the Design of Planar Antennas

  • Autoři: doc. Ing. Milan Polívka, Ph.D., Drahovzal, M.
  • Publikace: Conference Proceedings of Radioelektronika 2004. Bratislava: Slovak University of Technology, 2004. pp. 213-216. ISBN 80-227-2017-8.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The usage of higher order modes for realization of planar antennas with dualband performance and higher directivity has been studied with the help of IE3D planar simulator. 3.5/5.5 GHz linearly polarized dualband microstrip patch and 2.4 GHz three half wavelength slot radiator has been simulated. Structures of both planar radiators has been permormed in such a way so that broadside radiation has been achieved to be able to use them in an array.

Zobecněný přístup k problematice měření v mikrovlnné technice

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    V příspěvku jsou zmíněny metody měření, kalibrace a experimentální výsledky v oblasti mikrovlnné techniky.

Daulband Quarter Wavelength Plannar Antenna for Signal Detection in GSM 900/DCS 1800 Bands

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Properties of dual band quarter wavelength planar antenna for signal detection in GSM900/DCS1800 band are presented. The antenna consist of two quarter wavelength planar antennas with air dielectric with one point feed. Reflection coefficient in uplink subbands (from mobile station MS to base station BS) of both bands at presented antennas versions is not as good as is required for transmitting antennas but in case of antennas for signal detectionpurposes is quite goog enough. Directional characteristics has been measured too.

Education in Antennas - Phased Antenna Arrays

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper describes the new tasks related to the subjects taught at the Department of the electromangeic field. These tasks demonstrate the influences of supply amplitudes, supply phases, antenna element placement and antenna element parameters.

Education in Antennas - Phased Antenna Arrays

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper describes the new tasks related to the subjects taught at the Department of the electromagnetic field. These tasks demonstrate the influences of supply amplitudes, supply phases, antenna element placement and antenna element parameters.

Education in Antennas - Phased Antenna Arrays

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper describes the new tasks related to the subjects taught at the Department of the electromagnetic field. These tasks demonstrate the influences of supply amplitudes, supply phases, antenna element placement and antenna element parameters.

Fázované anténní řady

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Poster prezentuje úlohy, které vznikly jako projekt FRVŠ k podpoře výuky fázovaných anténních řad vyučovaných na katedře elektromagnetického pole. Tyto úlohy demonstrují vlivy amplitud a fázi napájecích proudů, rozmístění anténních elementů a vlivu jejich vlastních parametrů na celkový vyzařovací diagram řady a její parametry.

GA/MOM Approach for the Design of Planar Antennas

  • Autoři: Drahovzal, M., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Radioelektronika 2003 - Conference Proceedings. Brno: VUT v Brně, FEI, Ústav radioelektroniky, 2003. pp. 437-438. ISBN 80-214-2383-8.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Optimize size and shape of microstrip antennas, using numerical code in Matlab with genetic algorithm for optimization and moment method for analysing. Optimizing criterion is only impedance matching of antennas.

GA/MOM Approach for the Design of Planar Antennas

  • Autoři: Drahovzal, M., doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Poster 2003. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2003. p. C9. ISSN 0277-786X. ISBN 0-8194-5368-4.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Optimize size and shape of microstrip antennas, using numerical code in Matlab with genetic algorithm for optimization and moment method for analysing. Optimizing criterion is only impedance matching of antennas.

Internetová forma pilotního projektu LABLINK v úloze měření směrových vlastností antén

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Základní metodologie přípravy a provozu vzdálené výuky pomocí distančních laboratoří a virtuálních laboratoří.

Microwave Sensor for the Detection of Mobile Phones

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Microwave sensor for the detection of mobile services has been proposed based on the spectrum analyzer concept with advantages of RF wideband detectors. The sensor applies two or more RF channels for the separate detection of mobile services. Time-domain analysis is applied on the RF detector output voltage to further differentiate indvividual mobile services. Prototype of the sensor has been designed, realized and successfully tested.

Mikrovlnné antény zejména mikropáskového typu

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Radešín 2003 - Sborník příspěvků. Brno: VUT v Brně, FEI, 2003. pp. 14-15. ISBN 80-214-2479-6.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Článek představuje autora a jeho osobní i profesní zájmy. Stručně pojednává o předmětu jeho disertace, která se zabývá mikropáskovými patchovými anténami s modifikovanými tvary zářičů.

Návrh a vývoj antén

Simulace antén a mikrovlnných obvodů

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Příspěvek pojednává o použití simulátorů elektromagnetického pole dostupných na katedře elektromagnetického pole FEL CVUT v Praze k analýze vybraných typu mikrovlnných antén a obvodů.

Trendy technologie mikropáskových antén

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Odborné semináře - Sborník za rok 2002/2003. Praha: ČVUT FEL, Katedra elektromagnetického pole, 2003. pp. 35-41. ISBN 80-86582-12-4.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Příspěvek je věnován trendům technologie mikropáskových antén, kteréjsou ovlivněny zejména rozvojem mobilních radiotelefonních sítí od počátku 90. let min. stol. Mezi tyto trendy patří kompaktní uspořádání mikropásk. antén, které je dáno požadavky na minimalizaci rozměrů a dvoupásmový případně třípásmový provoz. Dalšími trendy jsoupoužívání umělých materiálů, které při interakci s elmag. polem vykazují specifické cování a mohou vylepšit vlastnosti antén a vývoj algoritmů snižujících výpočetní složitost při řešení integrálního tvaru Maxwel. rovnic pro planár. struktury.

Výuka antén s využitím softwaru MATHCAD

Education of Antenna Subjects with the Help of MathCad Software

Multiband Antennas for Signal Detection in Mobile Communications

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Odborné semináře. Praha: ČVUT FEL, Katedra elektromagnetického pole, 2002. pp. 28-32. ISBN 80-86582-08-6.
  • Rok: 2002

Návrh a vývoj antén

Software pro simulaci mikrovlnných obvodů a antén

Study of Trial Band Quarter Wavelenght Plannar Antenna for Signal Detection in NMT 450/GSM 900/DCS 1800 Bands

Antenna Laboratory

Demonstration 1800 MHz Antenna Array Building Set

Dual Band Mobile Phones Detector Imotel 900/1800

  • Autoři: doc. Ing. Milan Polívka, Ph.D., Procházka, A.
  • Publikace: COMITE 2001. Praha: IEEE Czechoslovakia Section, 2001. pp. 201-202. ISBN 80-902417-9-4.
  • Rok: 2001

Prezentace ČVUT na 43. ročníku mezinárodního strojírenského veletrhu a 1.ročníku mezinárodního veletrhu dopravy a logistiky Transport a Logistika v Brně ve dnech 24.-28. září 2001

  • Autoři: Lejčková, K., doc. Ing. Milan Polívka, Ph.D., Rataj, J., Smutný, V., Volf, J.
  • Publikace: Pražská technika. 2001, 3(5), 16-18. ISSN 1213-5348.
  • Rok: 2001

Anechoic and EMC Chambers - Modelling, Design, Testing

Design and Properties of Base Station Antenna Element for 1800 MHz Band

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Radioelektronika 2000 - Conference Proceedings. Bratislava: STU v Bratislave, FEI, 2000. pp. IV-38-IV-39. ISBN 80-227-1389-9.
  • Rok: 2000

EMC (EMI) Standards in RF Frequency Bands

Experimental Verification of the Second Leaky Wave on the Slotline

Flat Antennas for Telecomunications

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Proceedings of Workshop 99. Praha: České vysoké učení technické v Praze, 1999. pp. 201.
  • Rok: 1999

Low Profile Antennas

Parametric Study of Aperture Stacked Patch

Wideband Microstrip Antenna Design

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: 9th International Czech-Slovak Scientific Conference Radioelektronika 99. Brno: VUT v Brně, 1999. pp. 297-298. ISBN 80-214-1327-1.
  • Rok: 1999

IE3D Elektromagnetický software pro modelování plošných struktur s 3D prvky

  • Autoři: doc. Ing. Milan Polívka, Ph.D.,
  • Publikace: Workshop CAD&CAE'98. Praha: ČVUT FEL, Katedra elektromagnetického pole, 1998. pp. 38-39. ISBN 80-902417-2-7.
  • Rok: 1998

Microstrip Antennas as Probes for Near-Field Measurement

  • Autoři: doc. Ing. Milan Polívka, Ph.D., Houska, J.
  • Publikace: Workshop 98. Praha: České vysoké učení technické v Praze, 1998. pp. 269-270.
  • Rok: 1998

Parabolic Antenna Patch Feeder for 2,45 GHz Band

2.45 GHz Band Microstrip Array

Cavity Backed Patch Antenna with Shorted Nonradiating Edges

Cavity-Backed Path Antennas

  • DOI: 10.1049/cp:19970223
  • Odkaz: https://doi.org/10.1049/cp:19970223
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Several configurations of cavity-backed patch antennas are described and compared. Theoretical studies were accompanied with both impedance matching and radiation pattern measurements. The main goal of the project is to achieve smaller dimensions with a sufficient frequency bandwidth of microstrip low profile antennas. Two construction approaches-broadband cavity backed, shorted nonradiating edge, and slot & notch cut microstrip antenna-were combined

Combined Microstrip Antenna Arrangements

Patch Antennas with Reduced Dimensions

Automatizovaný systém pro měření směrových charakteristik antén

Electrically Small Spiral Transmission Line-Connected Triple-Arm Folded Monopole Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    We proposed electrically small spiral transmission line-connected triple-arm monopole antenna of cylindrical geometry with circumscribing sphere of the electrical length ka = 0.44. The diameter of the antenna base is λ0/10, and the monopole height is λ 0/20. EM simulation and analysis of radiation resistance as a function of number of monopoles is performed. It is shown that factor N2 appropriately takes into account increase of input resistance of parallel short monopoles even for their λ0/10 distance. A prototype has been designed for frequency 3 GHz with ground plane size 1.4 × 1.4 λ0 and provides relative bandwidth of 0.83 %, and measured efficiency of 81.7 %. Proposed structure is simple, and might be completely produced in single layer microstrip technology with linear vertical vias, potencially with additional air substrate layer to improve bandwidth as we present here.

Za stránku zodpovídá: Ing. Mgr. Radovan Suk