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doc. Ing. Pavel Hazdra, Ph.D.

Všechny publikace

Reconfigurable Antenna Array Testbed for Quantized Controlling

  • DOI: 10.1109/ACCESS.2024.3356358
  • Odkaz: https://doi.org/10.1109/ACCESS.2024.3356358
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Contemporary beam-forming antenna arrays often use a large number of individual elements, sometimes hundreds or more, to achieve high gain for advanced applications like radar, space communication, and next-gen cellular networks. These arrays are complex and costly due to the need for precise amplitude and phase adjustments across the elements. The feeding network complexity leads to signal losses, reduced efficiency, and higher noise. Current research aims to simplify arrays, reduce active elements needing frontends, and streamline the feeding network, considering non-uniform, sparse, parasitic, or reflective arrays. Challenges arise from element coupling and imperfect models of high-frequency materials and electronic components. Therefore, in addition to simulations, practical experimentation remains vital. This paper focuses on designing a novel 3 × 3 element antenna array with digital quantized control. We explore the impact of quantized control on beamforming and plan to validate simplified orthogonal optimization methods with limited quantization depth. The proposed antenna array is applicable to 2400 GHz band research, including arrays with parasitic elements and switchable polarization for individual elements.

Fabry-Perot Cavity based on Large-Core Graded-Index Multimode Fibers

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    We demonstrate design of fiber F abry-Perot c avities b ased o n large-core graded-index multimode fibers. Smallest full width at half maximum along with maximum transmission is reached for core diameters over 200mm core and reflectivity above 99%.

24-28 GHz Waveguide Antenna Array

  • Autoři: Lonský, T., Ing. Jan Kraček, Ph.D., doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: 15th European Conference on Antennas and Propagation. Bruxelles: The European Association on Antennas and Propagation, 2021. p. 1672-1674. ISBN 978-88-31299-02-2.
  • Rok: 2021
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A design of a compact three-element waveguide antenna array for the microwave frequency band 24–28 GHz is presented. The array is intended for 5G telecommunication systems where beamforming is necessary. Careful attention is paid on the design of its feeding lines to be of equal physical lengths. Therefore, beamforming phasing is significantly simplified. The proposed array is made using CNC machining and measured.

Deep reflector prime focus feed for space communication

  • DOI: 10.1049/tje2.12055
  • Odkaz: https://doi.org/10.1049/tje2.12055
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, design of a prime-focus feed for a deep reflector, Earth–Moon–Earth space communication system is described. The feed is based on a circular waveguide equipped with two chokes in order to minimise sidelobes and illuminate the deep dish with a high aperture efficiency of 70% . Based on sun noise measurements, it is estimated that the antenna system presents very low noise temperature values, below 30 K, making this feed favourable for space communication.

Experimental demonstration of a microwave photonic link using an optically phased antenna array for a millimeter wave band

  • DOI: 10.1364/AO.414069
  • Odkaz: https://doi.org/10.1364/AO.414069
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    We present a hybrid radiofrequency and microwave photonic link at 25 GHz using the chromatic dispersion of an optical fiber to steer the beam of a three-element planar dipole-based phased antenna array (PAA). Our team has designed and developed an in-house built PAA, experimentally verified its parameters, and successfully demonstrated optically controlled beam steering as measured in an anechoic chamber.Moreover, a detailed analysis of the optically based beam steering in the proposed microwave photonics system has been carried out, with data transmission achieving an error vector magnitude as low as 5.6% for the frequency of 25 GHz and 20 MHz bandwidth.

Shared-Aperture 24-28 GHz Waveguide Antenna Array

  • DOI: 10.3390/electronics10232976
  • Odkaz: https://doi.org/10.3390/electronics10232976
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A compact three-element shared-aperture waveguide antenna array for the 24–28 GHz microwave-frequency band is presented as a proof-of-concept of an array with steerable directional beam suitable for 5G telecommunication systems. The array is intended for use in a microwave photonic link and is sufficiently steerable only with the progressively phased excitation signals of equal magnitudes. The mutual interactions between the array elements are minimized to maintain the properties of the individual elements, even if they are embedded and closely spaced in the array. The proposed concept could be simply extended by adding more elements to further increase the directivity and enhance the steering properties of the array.

A Head/Taillight Featuring Hybrid Planar Visible Light Communications/Millimetre Wave Antenna for Vehicular Communications

  • DOI: 10.1109/ACCESS.2020.3006992
  • Odkaz: https://doi.org/10.1109/ACCESS.2020.3006992
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    With the emergence of the fifth generation and beyond mobile networks, both visible light communications (VLC) and radio frequency (RF) or millimetre wave (mmW) systems are expected to maintain the connectivity in various environments. In outdoor environments the link (VLC or RF) availability is paramount, which is affected by channel conditions. In particular, in vehicular communications other vehicles, harsh environment, and road geometry and structure will have the impact on the link connectivity and availability. In such cases, a front-end antenna solution, which benefits both optical and RF communication links, can be seen as an attractive option that can be fitted in future vehicles. In this paper, we present the design and practical implementation of a planar hybrid VLC/mmW antenna operating at 20.8 GHz and show measured results for characterization of RF and VLC links as well as communications performance. We have used the widely adopted on-off keying and quadrature amplitude modulation schemes with different orders todemonstrate data rates of 5 Mb/s and up to 100 Mb/s for the VLC and mmW links, respectively. By measuringthe bit error rate and the error vector magnitude for VLC and RF links, respectively for each modulation we have shown that the proposed hybrid planar antenna is suitable for example in a typical vehicle-to-ehicle communications.

Antenna Phased Array Beamforming at 26 GHz Using Optical True Time-Delay

  • DOI: 10.1109/CSNDSP49049.2020.9249587
  • Odkaz: https://doi.org/10.1109/CSNDSP49049.2020.9249587
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Multi-element antenna beam steering in freelicence higher frequency bands is one of the crucial features of 5G networks enabling better tracking of the users. In this paper, we present an experimental microwave photonics transmission system operating at 26 GHz where beamforming is fully realized in the optical domain. The system is designed to be deployed as a part of the mobile fronthaul network with an optical fiber span of 15 km. As a proof of concept, a planar 3-element antenna array has been developed and radiation patterns were measured in an anechoic chamber with high agreement between experimental and simulation results.

GNSS Sector Antenna for Interference Mitigation and Localization Using a High-Impedance Reflector

  • Autoři: Červený, M., doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: IEEE Antennas and Wireless Propagation Letters. 2020, 19(10), 1674-1678. ISSN 1536-1225.
  • Rok: 2020
  • DOI: 10.1109/LAWP.2020.3013910
  • Odkaz: https://doi.org/10.1109/LAWP.2020.3013910
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    There are many applications where the reception of global navigation satellite system (GNSS) signals is crucial. In such cases, the capability to reduce the interference (both unintentional or hostile) is critical. The proposed sector antenna offers a stable radiation pattern with no beam steering across the frequency band and good impedance matching. It also benefits from a high impedance reflector, which allows the antenna to provide broadband operation and low-profile compact geometry. Furthermore, seven of these sector antennas were placed in a heptagonal shape and combined with a broadband crossed dipole. As a result, the designed antenna system can reduce vertically polarized interference by approximately 45 dB in the required directions.

Optimization of Excitation and Geometry of Linear Dipole Array Above PEC Ground Plane for Directivity Maximization

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The modal approach was used to maximize the directivity of the linear dipole array above a perfect electric conductor ground plane. The directivity was maximized for the direction perpendicular to the ground in which this array can produce maximal directivity from all directions by a proper excitation. The modal approach was also connected with the optimization of geometrical parameters of the array to obtain not only optimal excitation currents for the array with fixed geometry but also optimal geometry of the array. It was observed that, thanks to the presence of the ground, the currents are equiphase and can be set to be real.

Superdirective Linear Dipole Array Optimization

  • DOI: 10.1109/LAWP.2020.2981533
  • Odkaz: https://doi.org/10.1109/LAWP.2020.2981533
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The theory of superdirective antenna arrays was discussed. The procedure for finding the excitation currents of fixed-geometry arrays, which maximizes the directivity, termed as superdirectivity, for a given direction and polarization, was described. The procedure was based on the solution of an eigenvalue problem including the directivity and matrices of normalized self- and mutual radiation intensities and normalized self- and mutual radiated powers of array elements. For examples of a linear dipole array located above a perfect electric conductor ground plane, this procedure was also combined with the optimization of the parameters of geometry of the array as a spacing of dipoles, or their height above the ground, for various number of dipoles in the array.

Fast Yagi-Uda Antenna Optimization

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Antenna arrays are widely used due to their properties in comparison to single element antennas. The possible achievable gain can be much higher. Also, one of the biggest advantages is the possibility to steer the main radiation beam and cover a wider area. The problematic part of obtaining maximum achievable directivity for antenna arrays is the corresponding feeding. In this paper, we use the one term sinusoidal current density excitation and more precise King’s three-term excitation for optimization of an array of four dipoles for maximum directivity. The goal of this paper is to present a new fast method for antenna array design and to compare its exactness. As an example, a four-element Yagi-Uda antenna is optimized.

On end-fire super directivity of arrays of two elementary dipoles and isotropic radiators

  • DOI: 10.1049/iet-map.2018.6013
  • Odkaz: https://doi.org/10.1049/iet-map.2018.6013
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The concept of source currents of a radiating source can be employed to express its directivity in some particular cases analytically. For an antenna array, this concept can be extended to the concept of a generalised directivity based on self- and mutual radiation intensities, self- and mutual radiated powers and excitation currents of array elements. These approaches were applied to examples of the array of two elementary dipoles and the array of two isotropic radiators. Particularly, the evaluation of the directivity of the end-fire arrays, which are of special attention due to superdirective properties, was treated. Novel closed-form expressions for the directivity of these arrays with out-of-phase excitation were derived. It was observed that the end-fire directivity can be further enhanced by optimising the excitation currents of the arrays. Their optimal phase difference and corresponding increased directivity were also found analytically. The results were validated by a full-wave simulator.

Superdirective Dipole Arrays

  • Autoři: Lonský, T., doc. Ing. Pavel Hazdra, Ph.D., Ing. Jan Kraček, Ph.D.,
  • Publikace: 2019 13TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP). IEEE (Institute of Electrical and Electronics Engineers), 2019. p. 1-3. ISSN 2164-3342. ISBN 9788890701887.
  • Rok: 2019
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper we develop and utilize theory for finding excitation currents that maximize the directivity of arbitrary dipole arrays. Such excitation is known as superdirective. It is shown that for arrays above perfectly electric ground, the corresponding optimal currents are purely real. It is also observed that for horizontally oriented dipoles, there exist optimum for spacing and height producing maximum obtainable directivity.

The Directivity of Two Closely Spaced Isotropic Radiators Above PEC Ground

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The concept of source currents of a radiating source can be employed to express its directivity in some particular cases analytically. For an antenna array, this concept can be extended to the concept of a generalized directivity based on self- and mutual radiation intensities, self- and mutual radiated powers and excitation currents of array elements. These concepts were applied to example of the array of two isotropic radiators above perfect electric conductor (PEC) ground, where the PEC ground is simulated by mirror image of the original image of isotropic radiators.

A Dual-Band Reflector Feed in Coaxial Configuration for Satellite Communication

  • DOI: 10.1109/MAP.2018.2859168
  • Odkaz: https://doi.org/10.1109/MAP.2018.2859168
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This article presents the design, simulations and measured results of a dual-band coaxial feed for satellite communication in the 2.4 and 10.45 GHz bands. The feed is designed for communication with the geostationary satellite. Es´hail 2 (scheduled to be lanched in late 2018), which will be equipped with a public amateur radio transponder covering nearly one-third of the Earth´s surface. A communication link can be established using a relatively low-power transmiller (Tx) employing conventional microwave technology. The proposed feed operates with linear polarization at the X-band and circular polarization at the S-band and has similar radiation patterns in both bands, providing high aperture efficiency for a broad range of reflector focal-to-diameter (f/D) ratios.

AToM: A Versatile MATLAB Tool for Antenna Synthesis

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The Antenna Toolbox For MATLAB (AToM), originally an in-house academic tool, has been transformed into a complete MATLAB toolbox, capable of modeling, discretizing and calculating arbitrarily shaped planar radiators while analysing the results. All tasks can be performed directly in MATLAB. The majority of the code allows its direct modification. AToM supports the latest features, used predominantly in the realm of electrically small antennas, namely modal decompositions, evaluation of fundamental bounds, and other techniques based on the source concept.

Characteristic Modes of Dipole Arrays

  • DOI: 10.1109/LAWP.2018.2828986
  • Odkaz: https://doi.org/10.1109/LAWP.2018.2828986
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The theory of characteristic modes is used to analyze antenna arrays. In particular, to study arrays of thin-wire dipoles backed by an infinite electric ground plane. The proposed theory is based on an analytically prescribed current distribution on the dipoles where, when compared with the full method of moments solution, only a self- and mutual impedance matrix relating excitation currents and voltages of array elements is the subject for modal decomposition. Therefore, the impedance matrix of interest has dimension N x N, where N is number of the array elements resulting in an extremely fast approach. The results of the proposed method are validated by a full-wave simulator and show good agreement.

Excitation of a Conducting Cylinder Using the Theory of Characteristic Modes

  • Autoři: Pascawati, A., doc. Ing. Pavel Hazdra, Ph.D., Lonský, T., Aziz, M.R.K.
  • Publikace: Radioengineering. 2018, 27(4), 956-959. ISSN 1210-2512.
  • Rok: 2018
  • DOI: 10.13164/re.2018.0956
  • Odkaz: https://doi.org/10.13164/re.2018.0956
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper describes the application of the theory of characteristic modes to exciete a conducting cylinder representing the chassis of a rocket. Mode excitation is achieved by cutting H-shaped slots on the cylinder at specific locations where the maximum of modal current distribution occurs. The L-matching network is designed to match the impedance of the slots to the input coaxial cable. Finally, the proposed concept is verified during manufacturing and measurement. It is shown that the measured results are in excellent agreement with the simulation.

Implementation of the Theory of Characteristic Modes into Antenna Modeling Tools AToM and Visual Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Two software packages suitable for the modeling of antennas and scatterers are presented. The approach of modal decomposition utilized leads to a better understanding of the radiation properties of the antennas studied and promises to reduce the length of the design process. Two examples are shown and the results are compared to an analytical solution, as well as to results from other simulators.

Modal efficiency of dipole arrays above ground

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D., Lonský, T., Ing. Jan Kraček, Ph.D.,
  • Publikace: 2018 12th European Conference on Antennas and Propagation. Bruxelles: The European Association on Antennas and Propagation, 2018. p. 1-3. ISSN 0537-9989. ISBN 978-1-78561-815-4.
  • Rok: 2018
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, the radiation efficiency modes of an array of lossy dipoles above infinite electric ground are evaluated. A simple theory, involving prescribed sinusoidal currents on dipoles, is presented. In turn, the impedance matrix of interest has dimension N × N where N is a number of the array elements resulting in an extremely fast approach. The ohmic losses are represented by a diagonal matrix and a particular eigenvalue equation is constructed. The modal efficiencies are studied as a function of the height of the array above the ground. The results are in good agreement with full-wave simulation.

Analytical Representation of Characteristic Modes Decomposition

  • DOI: 10.1109/TAP.2016.2632725
  • Odkaz: https://doi.org/10.1109/TAP.2016.2632725
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Aspects of the theory of characteristic modes, based on their variational formulation, are presented and an explicit form of a related functional, involving only currents in a spatial domain, is derived. The new formulation leads to deeper insight into the modal behavior of radiating structures as demonstrated by a detailed analysis of three canonical structures: a dipole, an array of two dipoles and a loop, cylinder and a sphere. It is demonstrated that knowledge of the analytical functional can be utilized to solve important problems related to the theory of characteristic modes decomposition such as the resonance of inductive modes or the benchmarking of method of moments code.

Characteristic Modes of Electrically Small Antennas in the Presence of Electrically Large Platforms

  • DOI: 10.1109/PIERS.2017.8262407
  • Odkaz: https://doi.org/10.1109/PIERS.2017.8262407
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The theory of characteristic modes can be applied to both electrically small and large objects. Its utilization, based on the electric-field integral equation using the Method of Moments and the Fast Multipole Method numerically implemented in Matlab, is described in this paper. Preliminary results and a comparison of both methods are presented on an example of a perfectly electrical patch.

Design of a plexiglass rod antenna

  • Autoři: Lonský, T., doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: 2017 Conference on Microwave Techniques (COMITE). Prague: Czechoslovakia Section IEEE, 2017. p. 1-5. ISBN 978-1-5090-4594-5.
  • Rok: 2017
  • DOI: 10.1109/COMITE.2017.7932300
  • Odkaz: https://doi.org/10.1109/COMITE.2017.7932300
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A dielectric rod antenna designed for maximal gain at the frequency band of 5-6 GHz is presented in this paper. A simulation using CST Microwave Studio results in gains of 12 to 15 dBi with beamwidths of 30° in both E and H planes making the dielectric rod antenna a sensible alternative to Yagi-Uda antennas as it performs in a similar fashion and is less sensitive to manufacturing tolerances. Multiple polymers were measured in order to find proper material for the rod resulting in using a cheap, affordable and low-loss material plexiglass.

Design of Closely Spaced Dipole Array Based on Characteristic Modes

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The Method of Moment, used for computation of the impedance matrix of the dipole array, is substituted here by faster method using simple approximation by the sinusoidal current. This method is verified by the theory of characteristic modes that provide a set of eigenvectors and eigenvalues, which are determined entirely by a structure's geometry at a certain frequency. When computing over a range of frequencies, the methods for eigenvalue tracking are essential. Proposed eigenvalue perturbation method is a powerful tool in this phenomena.

Evaluation of the Input Impedance and Impedance Quality Factor of a Dipole in Spatial and Spectral Domains

  • DOI: 10.13164/re.2017.0968
  • Odkaz: https://doi.org/10.13164/re.2017.0968
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In classic antenna analysis, there exist several methods of calculating input impedance when the source distribution of an antenna is known. The well-known induced EMF method, based on spatially distributed currents, is typically applied for this purpose and, thereby, serves as a reference for this research. Conversely, the spectral domain method takes the opposite approach for the input impedance and is evaluated using a far-field pattern. This paper compares the induced EMF method and the spectral domain method. Furthermore, the quality factor of the dipole antenna, based on the impedance variation with frequency, is calculated for both methods. This study shows that the induced EMF method and the spectral domain method are in close agreement.

Modal Decomposition for Arbitrary Dipole Array

  • DOI: 10.1109/COMITE.2017.7932302
  • Odkaz: https://doi.org/10.1109/COMITE.2017.7932302
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The Characteristic Mode Analysis (CMA) provides a set of eigenvalues and eigenvectors that are determined entirely by the antenna array structure at a particular frequency. The presented method solely relies on the mutual impedance matrix of elements of the array. In turn, the proposed approach is very fast. Various modal decompositions are performed on an array of parallel dipoles placed horizontally above an infinite electric ground plane. The dipoles have prescribed sinusoidal currents. The results are validated by a full-wave simulator FEKO, showing good agreement.

Modal Decomposition Theory for Arrays of Dipoles

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Various modal decompositions are performed on an array of dipoles backed by electric ground plane. The theory is based on analytically prescribed current on dipoles so the decomposition returns directly excitation coefficients of an array with respect to given quantity.

A Simple S/X Dual-Band Coaxial Feed for Satellite Communication

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Design concept of coaxial waveguide feed is often used for multi band antenna feeds. Cofiguration described in a paper has advantages in common phase center in the same aperture plane (for two bands), very high port to port isolation and easy of assembly.

An Introduction to the Source Concept for Antennas

  • DOI: 10.13164/re.2016.0012
  • Odkaz: https://doi.org/10.13164/re.2016.0012
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Antenna parameters particularly relevant to electrically small antenna design are reviewed in this paper. Source current definitions are accentuated leading to the introduction of the source concept which advantageously utilize only spatially bounded quantities. The framework of the source concept incorporates powerful techniques such as structural and modal decomposition, operator’s inversion and current optimization, thus opening new, challenging possibilities for antenna design, analysis and synthesis.

Bandwidth optimization of linear arrays above ground

  • DOI: 10.1109/EuCAP.2016.7481267
  • Odkaz: https://doi.org/10.1109/EuCAP.2016.7481267
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Two different array of dipoles above infinite electric ground plane are optimized for bandwidth using particle swarm optimizer, concept of self and mutual impedances and impedance quality factor. It is found that it is the interaction of mutual radiated power that limits the bandwidth, rather than stored energies.

Some numerical aspects of characteristic mode decomposition

  • DOI: 10.1109/EuCAP.2016.7481187
  • Odkaz: https://doi.org/10.1109/EuCAP.2016.7481187
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Characteristic mode decomposition represents popular and powerful numerical method which offers deep physical insight into radiation mechanisms and an effective framework for small antenna design. The quality of resultant characteristic basis is strongly dependent on the properties of the impedance matrix but also on utilized factorization technique, or the exact shape of the radiator. In this contribution, selected numerical aspects like incompleteness of the characteristic basis will be discussed. These observations will be proved to be important for practical usage of the characteristic modes.

A Novel Scheme for Stored Energy Evaluation

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The old and still unsolved problem of defining and evaluating stored electromagnetic energy is treated in this contribution. A novel time-domain scheme is proposed for evaluating the stored electromagnetic energy for non-stationary fields. In order to obtain the stored energy of the total electromagnetic energy, the well-known definition of radiated energy is utilized, and the subtraction is performed in the time domain during a transient state of the system under study.

An Analytical Evaluation of The Quality Factor Qz for Dominant Spherical Modes

  • DOI: 10.1049/iet-map.2014.0302
  • Odkaz: https://doi.org/10.1049/iet-map.2014.0302
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper describes an analytical evaluation of the quality factor Qz in a separable system in which the vector potential is known. The proposed method uses a potential definition of active and reactive power, implicitly avoiding infinite entire space integration and extraction of radiation energy. As a result, all the used quantities are finite, and the calculated Qz is always non-negative function of frequency. The theory is presented on the canonical example of the currents flowing on a spherical shell. The Qz for the dominant spherical TM and TE mode and their linear combination are found in closed forms, including both internal and external energies. The proposed analytical method and its results are compared to previously published limits of the quality factor Q.

Evaluating radiation efficiency from characteristic currents

  • DOI: 10.1049/iet-map.2013.0473
  • Odkaz: https://doi.org/10.1049/iet-map.2013.0473
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This study describes an effective technique for calculating modal radiation efficiency calculation based on decomposition into characteristic modes. The key assumption is that the current distribution on the perfect electric conductor is almost the same as in the case of a very good conductor, for example, metals such as copper, aluminium and silver. This assumption is verified against the conventional technique, the impedance boundary condition (IBC). The proposed approach does not require any modification of the formulation of method of moments for perfectly conducting surfaces, which is assumed for the modal decomposition. Modal efficiencies provide an additional insight that is useful especially for the design of small antennas. Taking the feeding into account, the modal losses can be summed up to obtain the total efficiency. The technique works perfectly for common metals, is fully comparable with the IBC, and can easily be incorporated into any present-day in-house solver. A numerical analysis of three antennas is presented to demonstrate the merits of the approach. Radiation efficiency of coupled dipoles, an electrically small meandered dipole, and PIFA were investigated by the presented method. The results are in perfect agreement with the reference commercial package.

On the Functional Relation Between Quality Factor and Fractional Bandwidth

  • DOI: 10.1109/TAP.2015.2414472
  • Odkaz: https://doi.org/10.1109/TAP.2015.2414472
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The functional relation between the fractional bandwidth and the quality factor of a radiating system is investigated in this note. Several widely used definitions of the quality factor are compared on two examples of RLC circuits that serve as a simplified model of a single resonant antenna tuned to its resonance. It is demonstrated that for a first-order system, only the quality factor based on differentiation of the input impedance has unique proportionality to the fractional bandwidth, whereas e.g. the classical definition of the quality factor, i. e. the ratio of the stored energy to the lost energy per one cycle, is not uniquely proportional to the fractional bandwidth. In addition, it is shown that for higher-order systems the quality factor based on differentiation of the input impedance ceases to be uniquely related to the fractional bandwidth.

The Antenna Toolbox for Matlab (AToM)

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This contribution presents recent development of the Antenna Toolbox for Matlab (AToM). The toolbox utilize novel theoretical findings related to characteristic mode decomposition and the so-called source concept, by which all antenna characteristics are represented solely by means of currents.

Time Domain Scheme for Stored Energy Evaluation

  • DOI: 10.1109/APS.2015.7305242
  • Odkaz: https://doi.org/10.1109/APS.2015.7305242
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A novel method for evaluation of the stored energy contained in a non-stationary electromagnetic field is presented in this paper. The method utilizes the classical definition of the radiated energy, which subtraction from the total electromagnetic energy is carried out in time domain during a transient state of the system under study.

A Method for Evaluating Radiation Efficiency Based on a Modal Approach

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Radiation efficiency is an important parameter, especially for electrically small antennas. It can be computed directly from the method-of-moments impedance matrix, and also more generally by employing modal decomposition through characteristic modes. This advantageously enables us to study separately the effect of the radiating shape and the feeding. The proposed method does not require any modification of the Electric Field Integral Equation implementation. A perfectly conducting antenna is considered as the only input to the modal decomposition. The conductive losses are taken into account once the surface currents are calculated. Good agreement is observed for the proposed treatment of the skin effect. Verification of the method is numerically performed on an fractal antenna, a thinstrip Sierpinski curve of various iterations. A full-wave software FEKO with implemented IBC is used for comparison purposes.

Aspects of mesh generation for characteristic-mode analysis

  • DOI: 10.1109/MAP.2014.6867702
  • Odkaz: https://doi.org/10.1109/MAP.2014.6867702
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper deals with practical aspects of mesh generation for the theory of characteristic modes. First, we describe a tool for surface-mesh generation in MATLAB. The tool is afterwards used for an analysis of relative convergence of modal results computed by an in-house modal analyzer in MATLAB. Different meshing scenarios are selected for a dipole, a rectangular patch, and a rectangular patch with a slot, and a recommendation for a mesh-refinement strategy is given. The study is supported by a simple error analysis, considering the approximation error in the evaluation of moment-matrix elements. It is shown that the results are also applicable for the commercial implementation in FEKO software.

Lower bounds of the quality factor QZ

  • DOI: 10.1109/APS.2014.6904358
  • Odkaz: https://doi.org/10.1109/APS.2014.6904358
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper describes an analytical evaluation of the measurable quality factor QZ of a system in which the vector potential is known. The method is presented on a canonical example of the currents flowing on a spherical shell, which leads to the analytical prescription for the lower bound of QZ.

Research on Compact Reflector Feeds for Space Applications

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This contribution describes our recent efforts in the research and design of special prime-focus feeds for reflector antennas intended for space communication using the Moon Bounce technique. Two contrasting structural designs are presented, illustrating the concept of multiband / multipolarization signal propagation. Besides space communication, these feeds may also be used in terrestrial radar and sensor systems.

The Measurable Q Factor and Observable Energies of Radiating Structures

  • DOI: 10.1109/TAP.2013.2287519
  • Odkaz: https://doi.org/10.1109/TAP.2013.2287519
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    New expressions are derived to calculate the Q factor of a radiating device. The resulting relations link Q based on the frequency change of the input impedance at the input port (QX, QZ) with expressions based solely on the current distribution on an radiating device. The question of which energies of a radiating system are observable is reviewed, and then the proposed Q factor as defined in this paper is physical. The derivation is based on potential theory rather than fields. This approach hence automatically eliminates all divergent integrals associated with electromagnetic energies in infinite space. The new formulas allow us to study the radiation Q factor for antennas without feeding (through e.g. Characteristic Modes) as well as fed by an arbitrary number of ports. The new technique can easily be implemented in any numerical software dealing with current densities. To present the merits of proposed technique, three canonical antennas are studied. Numerical examples show excellent agreement between the measurable QZ derived from input impedance and the new expressions.

The Radiation Q-Factor of a Horizontal lambda/2 Dipole Above Ground Plane

  • DOI: 10.1109/LAWP.2014.2329421
  • Odkaz: https://doi.org/10.1109/LAWP.2014.2329421
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Closed-form equations are given for radiation quality factor of a thin-wire =2 dipole above an infinite electric ground plane. Particular results of interest include a simple formula for a small separation between the dipole and the ground and for one dipole in free space.

The source definition of the quality factor QZ, 2014 IEEE International Symposium on Antennas and Propagation

  • DOI: 10.1109/APS.2014.6904357
  • Odkaz: https://doi.org/10.1109/APS.2014.6904357
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    New expressions for calculating of the quality factor QZ are presented. The resulting relations link QZ, based on the frequency change of the input impedance at the input port, with expressions based solely on the current distribution on a radiator. The derivation is based on electromagnetic potentials, automatically eliminating all divergent integrals associated with electromagnetic energies in infinite space.

Acceleration Techniques in Matlab for EM Community

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper describes some acceleration techniques in Matlab. Here, we strongly focus on acceleration of computational routines via High Performance Computing (HPC), which - in terms of Matlab software - includes parallel and distributive computing on CPU(s) and GPU computing. We also introduce an in-house antenna tool which is based on the Method of Moments and Theory of Characteristic Modes. Two numerically challenging examples are presented and then solved in Matlab

Comments to Reactive Energies, Impedance, and Q Factor of Radiating Structures by G. Vandenbosch

Implementation of the Theory of Characteristic Modes in MATLAB

  • DOI: 10.1109/MAP.2013.6529342
  • Odkaz: https://doi.org/10.1109/MAP.2013.6529342
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper describes the implementation of a complex MATLAB tool to calculate the characteristic modes and associated antenna parameters. The first code, written in FORTRAN, was presented in the early seventieths by Harrington and Mautz. Here, we utilize MATLAB, which is widely known and used in the antenna community these days. Because eigen-decomposition is time consuming, parallel and distributed computing is used. Thanks to the hundreds of built-in functions in MATLAB, computation of the surface currents from the eigenvectors obtained, as well as other important characteristics, are very easy and effective. The practical features are discussed with two examples.

A Method for the Evaluation of Radiation Q Based on Modal Approach

  • DOI: 10.1109/TAP.2012.2207329
  • Odkaz: https://doi.org/10.1109/TAP.2012.2207329
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new formula for the evaluation of the modal radiation Q factor is derived. The total Q of selected structures is to be calculated from the set of eigenmodes with associated eigen-energies and eigen-powers. Thanks to the analytical expression of these quantities, the procedure is highly accurate, respecting arbitrary current densities flowing along the radiating device. The electric field integral equation, Delaunay triangulation, method of moments, Rao-Wilton-Glisson basis function and the theory of characteristic modes constitute the underlying theoretical background. In terms of the modal radiation Q, all necessary relations are presented and the essential points of implementation are discussed. Calculation of the modal energies and Q factors enable us to study the effect of the radiating shape separately to the feeding. This approach can be very helpful in antenna design. A few examples are given, including a thin-strip dipole, two coupled dipoles a bowtie antenna and an electrically small meander folded dipole. Results are compared with prior estimates and some observations are discussed. Good agreement is observed for different methods.

Active Low Noise Differentially Fed Dipole Antenna

  • Autoři: Eichler, J., Segovia-Vargas, D., doc. Ing. Pavel Hazdra, Ph.D., prof. Ing. Miloslav Čapek, Ph.D., González-Posadas, V.
  • Publikace: Proceedings of the 10th International Symposium on Antennas, Propagation, and EM Theory. Piscataway: IEEE, 2012. pp. 1-4. ISSN 1045-9243. ISBN 978-1-4673-1799-3.
  • Rok: 2012
  • DOI: 10.1109/ISAPE.2012.6408766
  • Odkaz: https://doi.org/10.1109/ISAPE.2012.6408766
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    An active antenna based on a printed dipole directly connected to a differential amplifier is presented. The antenna covers the frequency band from 1.7-2.6GHz meaning the relative bandwidth of 41.86%. As the input impedance is mainly defined by the amplifier output, S 11 < -10dB was obtained in the whole frequency range. By designing both the active and the passive parts together a low equivalent noise temperature of 169K was obtained. The gain of the active antenna is higher than 15dBi. Antenna prototype was manufactured and measured. A good agreement between simulation and measurement was observed.

Compact Circular/Linear Polarization Dual-band Prime-focus Feed for Space Communication

  • DOI: 10.1155/2012/860951
  • Odkaz: https://doi.org/10.1155/2012/860951
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    We propose a novel, compact, prime-focus antenna feed for space communication. The feed requires full-wave simulator optimization for a given parabolic reflector and is designed to operate simultaneously on two bands, offering LHC/RHC polarizations for the 13 cm band and V/H polarizations for the 70cm band. With performance results confirmed by measurement, it has been verified in practice that this compact feed is suitable for use in a low-noise Earth-Moon-Earth communication link.

Modal Resonant Frequencies and Radiation Quality Factors of Microstrip Antennas

  • DOI: 10.1155/IJAP
  • Odkaz: https://doi.org/10.1155/IJAP
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The chosen rectangular and fractal microstrip patch antennas above an infinite ground plane are analyzed by the Theory of characteristic modes. The resonant frequencies and radiation Q are evaluated. An novel method by G. Vandenbosch for rigorous evaluation of the radiation Q is employed for modal currents on a Rao-Wilton-Glisson (RWG) mesh. It is found that the resonant frequency of a rectangular patch antenna with a dominant mode presents quite complicated behaviour including having a minimum at a specific height. Similarly, as predicted from the simple wire model, the radiation Q exhibits a minimum too. It is observed that the presence of out-of-phase currents flowing along the patch antenna leads to a significant increase of the Q-factor.

On the Modal Resonant Properties of Microstrip Antennas

  • DOI: 10.1109/EuCAP.2012.6206511
  • Odkaz: https://doi.org/10.1109/EuCAP.2012.6206511
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The chosen rectangular and fractal microstrip patch antennas above an infinite ground plane are analyzed by the Theory of characteristic modes. The resonant frequencies and radiation Q are evaluated. An method by G. Vandenbosch for rigorous evaluation of the radiation Q is employed for modal currents on a Rao-Wilton-Glisson (RWG) mesh. It is found that the resonant frequency of a rectangular patch antenna with a dominant mode presents quite complicated behaviour including having a minimum at a specific height. Similarly, as predicted from the simple wire model, the radiation Q exhibits a minimum too. It is observed that the presence of out-of-phase currents flowing along the patch antenna leads to a significant increase of the Q-factor.

The Evaluation of Total Radiation Q Based on Modal Aproach

  • DOI: 10.1109/EuCAP.2012.6205873
  • Odkaz: https://doi.org/10.1109/EuCAP.2012.6205873
  • Pracoviště: Katedra matematiky, Katedra elektromagnetického pole
  • Anotace:
    The total Q of selected structures is to be calculated from the set of eigenmodes with associated eigen-energies and eigen-powers. Thanks to the analytical expression of these quantities, the procedure is highly accurate, respecting arbitrary current densities flowing along the radiating device. The electric field integral equation, Delaunay triangulation, method of moments, Rao-Wilton-Glisson basis function and the theory of characteristic modes constitute the underlying theoretical background. Calculation of the modal energies and Q factors enable us to study the effect of the radiating shape separately to the feeding. To outline some benefits of proposed method, the total radiation Q of a Huyghens source is calculated for several distances between a loop and an dipole.

A Method for Tracking Characteristic Numbers and Vectors

  • DOI: 10.2528/PIERB11060209
  • Odkaz: https://doi.org/10.2528/PIERB11060209
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new method for tracking characteristic numbers and vectors appearing in the Characteristic Mode Theory is presented in this paper. The challenge here is that the spectral decomposition of the moment impedance-matrix doesn't always produce well ordered eigenmodes. This issue is addressed particularly to nite numerical accuracy and slight nonsymmetry of the frequency- dependent matrix. At specic frequencies, the decomposition problem might be ill-posed and non-uniquely dened as well. Hence an advanced tracking procedure has been developed to deal with noisy modes, non-continuous behavior of eigenvalues, mode swapping etc. Proposed method has been successfully implemented into our in-house Characteristic Mode software tool for the design of microstrip patch antennas and tested for some interesting examples.

Design of a Dual-Band Orthogonally Polarized L-Probe-Fed Fractal Patch Antenna Using Modal Methods

  • DOI: 10.1109/LAWP.2011.2178811
  • Odkaz: https://doi.org/10.1109/LAWP.2011.2178811
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Modal methods are used to effectively design a dual-band orthogonally polarized fractal patch antenna. This letter summarizes the workflow from generating a fractal motif through modal analysis to feeding design and full-wave analysis. As the antenna's feeding and matching structure, a dual L-probe was proposed to widen its bandwidth. The full-wave simulation is in very good agreement with the measurement. The motif size is 50 50 mm, and the antenna operates at 1.25 and 2.1 GHz. The relative bandwidths are 4.18% and 11.4%, respectively.

Multiobjective optimization of Fractal Radiating Structures Using Modal Decomposition

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper describes in-house developed software tools for design of microstrip patch fractal antennas. As the fractal geometry is quite complex, IFSMaker application was developed purposedly for an easy maintaining of planar fractal structures. In the next step, we are using cavity model technique for modal analysis of internal fields of the patch. This simplified model is reasonably fast, so that optimization loop may be employed in order to reduce the fundamental mode resonant frequency. Particle swarm optimization is used and the PSOoptimizer tool was created to handle it. Theory of characteristic modes (TCM) is then used to refine the results. The crucial problem of use of TCM in the optimization loop is the proper sorting of characteristic modes. The sorting problem is discussed and new method is presented.

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.

Radiation Q of Dipole Modal Currents

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: Proceedings of the 5th European Conference on Antennas and Propagation (EuCAP). Piscataway: IEEE, 2011. pp. 1671-1674. ISBN 978-88-8202-074-3.
  • Rok: 2011
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper we present an investigation into the radiation Q-factor of modal currents on a dipole antenna. First, we study the validity of the used thin-wire approximation with a reduced kernel. Different approaches of Q calculation are discussed and finally, the Q of coupled dipole antennas is evaluated. Good agreement between the assumed sinusoidal current distribution and the real cylindrical antenna modeled with the full-wave MoM is observed.

Radiation Q-Factors of Thin-Wire Dipole Arrangements

  • DOI: 10.1109/LAWP.2011.2158050
  • Odkaz: https://doi.org/10.1109/LAWP.2011.2158050
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this letter, we present an investigation of the radiation -factors of two coupled thin dipole antennas with sinusoidal current distribution. The approach is based on novel rigorous equations for radiated power and stored energies recently derived by Vandenbosch. First, we study the validity of the used thin-wire approximation with a reduced kernel. Good agreement between the assumed sinusoidal current distribution and the real cylindrical antenna modeled with the full-wave method of moments (MoM) is observed. Then, radiation -factors are evaluated for half-wave side-by-side coupled dipole antennas with different feeding configurations. It is found that every such combination of studied coupled dipoles presents minimum for specific feeding arrangement and separation distance.

Small dual-band fractal antenna with orthogonal polarizations

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Modal methods are effectively used to design dual band fractal patch antenna. This contribution summarizes the workflow from generating fractal motif through choosing proper feeding to final antenna completion. As an antenna's feeding and matching structure, dual L-probe was proposed to widen its bandwidth. Moreover, the polarizations on operating bands are mutually orthogonal. This behavior is easily explained by modal decomposition of the surface currents. Antenna was fabricated and measured. © 2011 EurAAP.

Software Tools for Efficient Generation, Modeling and Optimisation of Fractal Radiating Structures

  • DOI: 10.1049/iet-map.2010.0269
  • Odkaz: https://doi.org/10.1049/iet-map.2010.0269
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper describes in-house developed software tools for design of microstrip patch fractal antennas. As the fractal geometry is quite complex, IFSMaker application was developed purposedly for an easy maintaining of planar fractal structures. In the next step, we are using cavity model technique for modal analysis of internal fields of the patch. This simplified model is reasonably fast, so that optimisation loop may be employed in order to reduce the fundamental mode resonant frequency. This is accomplished with the valInFEM, PSOoptimizer and IFSLimiter applications. Theory of characteristic modes is then used to refine the results and finally antenna is simulated with full-wave CST simulator, built and measured.

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.

Advanced Modal Techniques for Microstrip Patch Antenna Analysis

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper shows the advantage of modal methods utilization in the area of microstrip patch antennas design. Namely, the Theory of Characteristic Modes (TCM) is developed starting from the Electric Field Integral Equation and formulating proper functional equation for stored and radiated power. Developed in-house TCM analyzer is presented and employed to investigate properties of the linearly and circularly polarized rectangular patch antenna.

Design of IFS Patch Antenna Using Particle Swarm Optimization

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper describes usage of the IFS (Iterated Function System) fractals employed as a planar microstrip patch antennas. To generate the IFS fractals, versatile tool named IFSMaker has been evolved. Efficient design of patches will be shown. After fractal pre-design, one can start to optimize the IFS collage by using the PSO algorithm. This procedure is managed by the PSOptimizer tool. Optimalization loop (which includes IFS generator, cavity model (CM) solver and PSO evaluation) works generally with any number of optimalization conditions. This feature is provided by IFSLimiter tool. Resonant frequencies (eigenvalue problem) are calculated with cavity model in Comsol Multiphysics environment. Finally we discuss the radiation pattern calculation and usage of theory of characteristic modes as well.

Wideband Shorted Backfire Antenna with L-probe fed Microstrip Patch

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this contribution a novel configuration of highdirectivity broadband antenna is presented. Its main operational principle is based on the so-called "short backfire" (SBF) concept, however, instead of conventional dipole, rectangular microstrip patch is used as feeder.

Antenna Noise Temperature - Software Tools

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Designers of antennas and their associated components presently enjoy the convenience of performing fast, accurate, automated, design-related calculations due to the availability of a multitude of software "design tools" for modelling electromagnetic fields. Computations involved with specific problems such as antenna noise temperature, however, require supplementary software tools to augment the capability of these general purpose state-of-the-art professional programs. To adress this need, we have developed the "Antenna Noise Temperature Calculator" software program that utilizes either modeled or measured radiation patterns to calculate antenna noise performance parameters.

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.

Optimization Tool for Fractal Patches Based on the IFS Algorithm

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents set of software tool for the design and optimization of fractal patches describes by the IFS.

Two-Element PIFA Array Structure for Polarization Diversity in UMTS Mobile Phones

  • Autoři: Ferrero, F., Diallo, A., Luxey, C., Derat, B., Hamouz, P., doc. Ing. Pavel Hazdra, Ph.D., Rahola, J.
  • Publikace: Radioengineering. 2009, 2009(4), 407-412. ISSN 1210-2512.
  • Rok: 2009
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    We demonstrate the possibility to strongly modify the radiated fields of a UMTS handset by using a phased two-element PIFA array. The structure is composed of a 100x40 mm2 metallic ground plane acting as the Printed Circuit Board (PCB) of the mobile phone. Two UMTS PIFAs are located at the top edge of this PCB. They are fed by a double Quasi-Lumped Coupler able to provide phase difference in the range from 0° to 360° between its two outputs. In this way the two-element array is able to radiate different electromagnetic fields. Simulated and measured radiation patterns in the two main planes of the chassis are presented for different phase differences. It is especially revealed that the novel two-antenna structure is able to radiate vertically and horizontally-polarized electric fields in the same plane when changing the phase shift between the antennas from 0° to 180°. Potential applications are polarization-diversity techniques and Specific Absorption Rate reduction for handsets.

UWB Dipole Antenna Optimization with Neural Network Tuned Algorithm

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper describes an improved approach in an optimization of different UWB dipole antennas. The new procedure of tuning different optimization algorithms is presented. Fine-tuning of optimizing algorithm which is not elementary problem is discussed.

Design of a Prime-Focus Feed with Backward Radiation

  • Autoři: Sláma, L., Galuščák, R., doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. pp. 35-38. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper describes the design of a highly effective parabolic dish antenna primary feed based on backward radiation. This assembly, comprising a dielectric lens and reflecting plate, supports both linear and circular polarization and may be directly attached to a circular waveguide. The current design is intended to work in the 10 GHz band with the specified parabolic dish antenna.

Design of Primary Feeds for 32m KDDI Antenna System IBA-4 in Cassegrain Configuration

  • Autoři: Galuščák, R., Watanabe, M., doc. Ing. Pavel Hazdra, Ph.D., Takeda, S., Seki, K., Procházka, M., Uchiyama, Y.
  • Publikace: Radioengineering. 2008, 17(1), 20-27. ISSN 1210-2512.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The article is discussing about design, fabrication, testing and use an antenna system based on the KDDI IBA-4 antenna in Cassegrain configuration, and transformation it into a multiband antenna for 2m, 70cm and the 23 cm bands.

Dual-band Loop Feed with Enhanced Performance

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper is aimed on specific problems of electrically small and deep dish parabolic antennas. Since these antennas may suffer with low efficiency authors describe design and optimization of simple dual-band loop prime-focus feed achieving good efficiency for these antennas.

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.

IFS Tool for Fractal Microstrip Patch Antenna Analysis

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D., Čapek, M.
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. pp. 227-230. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper describes development of Iterated Function System (IFS) software tool for the generation and modal analysis of microstrip fractal patches. This tool is able to effectively create almost arbitrary plane fractal and to prepare its shape for further (modal, full-wave) EM calculations.

On the Modal Superposition Lying under the MoM Matrix Equations

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This article shows an interesting sight on the correspondence between total current solution obtained by the Method of Moments and by the Characteristic modes respectively. Derivation is based on representation of a matrix in its spectral form. Detailed study of dipole antenna fed under different conditions is presented demonstrating that modal decomposition of currents offers a nice physical insight into behavior of radiating structures.

PSO optimalizace v MATLABU

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Příspěvek se věnuje implementaci PSO algoritmu v Matlabu. PSO je stále relativně novou, velice rychlou a robustní technikou, která podává ve většině případů výborné výsledky. Algoritmus je rozšířen o tzv. zdi, které celou optimalizaci zrychlují. Probrány jsou i jednotlivé parametry, které průběh optimalizace ovlivňují.

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.

Modal Analysis of Miniature Microstrip Patch Antennas Based on Fractal Geometry

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper deals with modal analysis of electrically small patch antennas. Cavity model and the Theory of characteristic modes are used for analysis, one sample is simulated with CST Microwave Studio also.

Prime-focus Circular Waveguide Feed with Septum Polarization Transformer

  • Autoři: Galuščák, R., doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: DUBUS - Magazine for Amateur Radio on VHF/UHF and Microwaves. 2007, 36(1), 8-32. ISSN 1438-3705.
  • Rok: 2007
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper describes design of the prime-focus circular waveguide feed with septum polarization transformer, working at radioamateur 13 and 23cm bands. Proposed feed structure exhibit excellent parameters in terms of return loss, izolation and axial ratio. Simulated results were confirmed by several measurements.

Theory of Characteristic Modes and its Applications for Analysis of Fractal Microstrip Patch Antennas

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper deals with the fractal microstrip patch antennas with specific properties based on special fractal geometrical modifications. Desctiption of physical behavior via surface current distribution is discussed. Different modal analysis approaches (Cavity model and the Theory of characteristic modes) as well as full-wave EM tools have been used for the simulations.

Theory of Characteristic Modes: Getting More Insight into Linear Antenna Behavior

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The Theory of Characteristic Modes is a very useful tool to get physical insight into antenna behavior. It is possible to easily obtain resonant frequencies, modal radiation Q or bandwidth, modal currents and modal radiation patterns. The paper is intended to study well known linear antennas under this new point of view.

Wideband Rectangular Microstrip Patch Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper focuses on so-called L-probe feeding technique suitable for wideband (<30% relative band-width) driving of microstrip patch antennas. Physical explanation, simulation and measurement are presented. Further modification for improvement of radiation characteristic is also proposed.

Circular Polarization and Polarization Losses

  • Autoři: Galuščák, R., doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: DUBUS - Magazine for Amateur Radio on VHF/UHF and Microwaves. 2006, 2006(35), 8-17. ISSN 1438-3705.
  • Rok: 2006
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Circularly polarized microwave radiation is frequently used in EME (Earth-Moon-Earth) communication on the 23, 13 and 6 cm bands. Recently. The main advantage of CP versus linear polarization is that CP eliminates polarization mismatch losses caused by Faraday's rotation and varies the squint angle of polarization vectors between stations on the Earth. This article is intended to familiarize and clarify the application of CP in conjunction with parabolic reflector antennas and to publicize problems that CP antenna designers may encounter.

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.

L-System Tool for Generating Fractal Antenna Structures with Ability to Export into EM Simulators

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    An L-System (Lindenmayer system) is a scheme primarily developed in the area of the computer science for simulating the development of biological structures. It has also been found very useful for generating the geometry of various fractal antennas. A Matlab environment has been used for both implementing an in-plane L-systems algorithm and for creating appropriate files for widely used EM simulators like the IE3D and the CST Microwave Studio. Sinally, the performance of the developed script is demonstrated on two fractal microstrip patch antennas.

Measurement of Shielding Effectiveness of Small Enclosures

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The evaluation of the Shielding Effectiveness (SE) brings great challenges from the EMC measurement point of view. Particularly in the case of measurement of small enclosures, many different approaches can be used. Therefore, based on an extensive measurement campaign, various aspects of measurement of the shielding effectiveness of small metallic enclosures were investigated. Significant results of this campaign are discussed in this paper.

Miniature Microstrip Fractal Patch Antenna Working with Crossed-Diagonal Mode

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper describes a novel type of miniature microstrip patch antenna based on fractal geometry. Miniature properties are achieved by the presence of unusual fundamental resonant mode which we call "crossed-diagonal" (CD) current.

Modeling in Education of Antennas

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper is focused on the key role of modeling in education process in the field of antennas. Attention is turned not only to the modeling, but to the whole structure of education. Depending on the level of study, the balanced 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.

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.

Optimalization of the Septum Polarizer Feed for 1.296 GHz EME

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    We describe the reduction of polarization losses and other optimizations in the design of a septum polarizer antenna feed configured in a circular waveguide. The goal is to improve the overall efficiency of a parabolic dish antenna system which will be used for EME (Earth-Moon-Earth) microwave communication.

A Key Role of Simulation in New Approach to Electromagnetics Education

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper describes the examples in teaching electromagnetics at the Czech Technical University in Prague. Due to the abstract nature of electromagnetics, computer simulations play an important role here. The paper describes the way of the efficient incorporation of simulations to the teaching process. We emphasize the simulations have to be deeply analyzed together with students to improve their inderstanding of the physical matter of electromagnetic phenomena.

CAD/CAM ve výuce předmětů katedry elektromagnetického pole FEL - ČVUT v Praze

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    V článku je popsáno použití nástrojů CAD/CAM pro výuku na katedře elektromagnetického pole FEL ČVUT v Praze. Katedra disponuje několika softwarovými produkty, které jsou v současné době považovány za nejvyspělejší a jsou schopny simulovat komplexně elektromagnetické problémy. Nejdůležitější simulátory jsou zde popsány současně s jejich pedagogickým využitím.

Measurement of a Shielding Effectiveness of Relatively Small Metallic Enclosures

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Paper presents several results of the study and experimental verification of a shielding effectiveness of relatively small metallic enclosures, which operate above the first resonance. There is no standard for measurement and therefore different aspects of measurement and methodology are discussed. Relative size, volume, quality factor of the enclosure, position, radiator type, reciprocity etc. are discussed.

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.

Miniature Microstrip Fractal Patch Antenna FED by J-Probe

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper describes a novel kind of miniature fractal microstrip patch antenna based on the Inverted koch Square fractal. Tuning possibilities were extended by using the J-probe with more degrees of freedom compared to a conventional L-probe. A parametric study was performed using a full-wave simulator IE3D.

Miniaturization of Patch Antennas using Fractal Geometry

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: 9th International Student Conference on Electrical Engineering. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2005. pp. C6.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Miniaturization of patch antennas is a very recent topic. Novel kind of miniature fractal patch antenna based on Inverted Koch Square fractal with variable indentation angle is studied. L-System generator was used to create the desired geometry. Impedance and radiation behavior of proposed antennas are numerically studied with IE3D MoM simulator and partially by modal analysis as well.

Miniaturized Wide-Band Dielectric Resonator Antenna for Next Generation WLAN Applications

  • Autoři: Rashidian, A., Tayfeh, M., doc. Ing. Pavel Hazdra, Ph.D., Forooraghi, K.
  • Publikace: European Microwave Week 2005 Conference Proceedings. London: Horizon House Publications, 2005. pp. 85-87. ISBN 2-9600551-2-8.
  • Rok: 2005
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this paper, a set of two-segment dielectric resonator antennas is investigated for 5-6GHz WLAN applications, which covers the requirements of most of the new standards, in this area. It is shown that by choosing a high dielectric constant for the upper segment of the antenna, a good miniaturization can be achieved in spite of a proper wide impedance bandwidth. A practical antenna is then studied in detail which attains more than 50% size reduction and 20% impedance bandwidth.

Normalized Site Attenuation (NSA) Measurement

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Normalized site attenuation testing (NSA) is the process to evaluate the quality of test site for EMC testing. The standard EMC measurement uses the NSA in the frequency range 30 MHz - 1 GHz. It is supposed the use of higher frequencies for EMC measurement in a near future, where the measurement of wall reflections is usually recommended for site testing. Experiences based on the measurement of NSA, the antennas and its calibration (antenna factor), polarization and geometry of measurement and parasitic influence of floor reflections are mentioned in the paper. Problems of EMC test sites are also discussed with pedagogical aspects from point of view Electromagnetic Field Theory and its simulation tools.

Shielding Effectiveness Measurement Issues for Small Enclosures

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Shielding Effectiveness (SE) is one of the major aspects of any EMC design process. In this paper, a detailed analysis of measurement issues of a shielding effectiveness of relatively small metallic enclosures is presented. An extensive measurement campaign has been done to investigate various aspects of measurement of the small enclosures shielding effectiveness.

The Miniature Fractal Patch Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In this work we study novel kind of miniature and broadband fractal patch antenna based on Inverted Koch Square Fractal with variable indentation angle. L-System generator was advantageously used to create desired geometry with possibility of adjusting its properties. Impedance and radiation behavior of proposed antennas are numerically studied with IE3D MoM simulator and partially by modal analysis as well.

The Miniature Inverted Koch Square Microstrip Patch Antenna

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Novel kind of miniature and broadband fractal patch antenna based on inverted Koch square fractal with variable indentation angle is studied. L-System generator was advantageously used to create desired geometry with possibility of adjusting its properties. Impedance and radiation behavior of proposed antennas are numerically investigated with IE3D MoM simulator and partially by modal analysis as well.

Vzdělávání v elektromagnetismu na rozcestí

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    V příspěvku je diskutována současná úloha výuky elektromagnetismu na elektrotechnických fakultách. Je zmíněno použití elektromagnetických simulátorů ve výuce a popsán praktický struktorovaný příklad výuky na popisu vyzařování liniového zářiče.

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.

Multifyzikální systém FEMLAB

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: Počítačové prostředky pro mikrovlnnou techniku. Praha: Česká elektrotechnická společnost, 2004. pp. 40-43.
  • Rok: 2004

Návrh a vývoj antén

On the Modal Anylsis of Fractal Microstrip Patch Antennas

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Full wave simulation of complex structures presented by fractal microstrip patches is very difficult and time-consuming. Cavity model has been found to be very useful and fast in obtaining basic parameters of such structures like resonant frequencies, field distribution and radiation pattern. Comparison with full-wave simulation results to reliable agreement.

Planar Patch Antennas with Fractal Boundary

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper describes an innovative approach for the simulation of the microstrip patch antennas with fractal boundary. First, L-System based fractal generator with the possibility of exporting the desired geometry into various EM simulators has been developed. Before the full-wave simulation is performed, modal analysis to predict the resonant frequencies, field distribution and radiation pattern is employed.

Planární fraktálové antény

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: Odborné semináře - Sborník za rok 2003/2004. Praha: Československá sekce IEEE, 2004. pp. 69-70. ISBN 80-86582-14-0.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Příspěvek se zabývá poznatky z oblasti analýzy planárních antén na bázi fraktálové geometrie. Jedná se zejména o problematiku návrhu vlastní fraktálové geometrie a metody analýzy planárních fraktálových antén.

Shielding Effectiveness of a Relatively Small Metallic Enclosure

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper present several results of the study and experimental verification of a shielding effectiveness of relatively small metallic enclosures, which operates above the first resonance. Different aspects of measurement and methodology are discussed - including relative size, volume, quality factor of the enclosure, position and radiator type, reciprocity measurement etc.

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.

Simulace elmag. pole, fraktálové antény

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: Sborník příspěvků konference RADEŠÍN 2004. Brno: FEKT VUT v Brně, 2004. pp. 44-45. ISBN 80-214-2726-4.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    V příspěvku jsou uvedeny výsledky modelování elektromagnetického pole, je popsána nová metoda generace fraktálových geometrií.

Widely Configurable L-System Fractal Antenna Generator

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    An L-System (Lindenmayer System) is a scheme primarily developed in the area of computer science for simulatin the development of biological structures. It has been found very useful for generatin the geometry of various fractal antenna structures. Matlab has been used for both implementing L-systems algorithm in 2D and creating appropriate files for widely used EM simulators like IE3D and CST-Microwave Studio.

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.

Design, Simulation and Results of the Microstrip Fractal Boundary Patch Antenna

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: Poster 2003. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2003. p. C14. ISSN 0277-786X. ISBN 0-8194-5368-4.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This work deals with design, simulation and measurement of the microstrip patch antenna with fractal boundary. Proposed antenna is designed to work on higher resonant mode where localization of the boundary-electric field is observed. Thus significantly higher directivity compared to conventional patch antenna is achieved. Preliminary quasistatic modal analysis is treated using FEM and the results are refined by using IE3D full wave EM simulator. Simulation results were finally compared with measurement.

Efficient Analysis of the Microstrip Patch Antenna with Fractal Boundary

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Microstrip patch antenna with fractal boundary defined by Koch curve is introduced. The antenna is designed to work at higher operating mode wich exhibit localization property of the electric field close tothe antenna's boundary. Such higher eigenmode results in higher directivity. Antenna is solved in terms of the cavity model using FEM and resultsare refined by full-wave simulator IE3D. Good agreement between measurement and simulation was achieved.

Microstrip Patch Antenna with Fractal Boundary: Design, Simulation and Results

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Microstrip patch antenna with fractal boundary defined by Koch curve is introduced. The antenna is designed to work at higher mode which exhibit localization property of the electric field close to the antenna's boundary. Such higher eigenmode results in higher directivity. Antenna is solved in terms of the cavity model using FEM and results are refined using full-wave electromagnetic simulator IE3D. Good agreement between measurement and simulation was achieved.

Návrh a vývoj antén

Simulace a vizualizace elmag. pole

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: Radešín 2003 - Sborník příspěvků. Brno: VUT v Brně, FEI, 2003. pp. 12. ISBN 80-214-2479-6.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Příspěvek představuje autorovu práci jako postgraduálního studenta na katedře elektromagnetického pole FEL ČVUT. Autor se zajímá o studium fraktálových antén a o simulaci a visualizaci elmag. pole. Pro tyto účely ovládá řadu simulátorů elmag. pole jako jsou IE3D, CST-Microwave Studio, Microwave Office a Femlab.

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.

Microstrip Patch Antennas with Fractal Boundary

Mikropáskové antény s fraktální hranicí

Numerical Analysis of Microstrip Patch Antennas with Fractal Boundary

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: POSTER 2002 - Book of Extended Abstracts. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2002. pp. C10.
  • Rok: 2002

Software pro simulaci mikrovlnných obvodů a antén

Behavior of the Sierpinski Monopole Iterations

Fractal Structures in Antenna Technology

Fractals in Antenna Technology - New Analysis Approach

Novel Approach to the Sierpinski Monopole Analysis

  • Autoři: doc. Ing. Pavel Hazdra, Ph.D.,
  • Publikace: Poster 2001. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2001. pp. E5.
  • Rok: 2001

Sierpinski Monopole Fractal Antenna - Simulation and Results

Za stránku zodpovídá: Ing. Mgr. Radovan Suk