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prof. Ing. Zbyněk Škvor, CSc.

Všechny publikace

Evaluation of Insertion Losses of Power EMC Filters Operated in Actual Impedance Environment

  • DOI: 10.1109/TMTT.2024.3377997
  • Odkaz: https://doi.org/10.1109/TMTT.2024.3377997
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Insertion losses (ILs) of power electromagnetic com- patibility (EMC) filters are measured often up to the relatively high GHz region, usually by standard microwave 50- vector network analyzers (VNAs) in accordance with related standards. However, the obtained S-parameters do not correspond to condi- tions when the filters are connected to impedances of actual power sources and loads. Evaluated examples show that actual opera- tional ILs can be significantly lower than values obtained directly from 50- measurements. The presented virtual measurement method uses 50- S-parameter measurements and subsequently processes the data using the newly derived evaluation formulas applicable for any filter sources and loads at any frequencies. Parameters of three different particular power cables employed as practical sources and loads are measured in the frequency band from 0.1 to 10 GHz. These data are used for the proposed advanced insertion loss calculations. The results demonstrate the influences of practical cable input impedances on power filter ILs for common-mode (CM) and differential-mode (DM) transmissions, and their conversions. Related to common 50- measurements, the operational IL drops can reach almost 40 dB for CM–CM transmissions, 5 dB for DM–DM transmissions, and 20 dB for CM–DM conversions. This proves that the practical information capabilities of the standard 50- evaluation are really limited.

Impact of crest factor on indication quality in the magnetic particle inspection process

  • DOI: 10.1080/10589759.2022.2066663
  • Odkaz: https://doi.org/10.1080/10589759.2022.2066663
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Magnetic particle inspection is a well-established industrial process of quality control. The ISO standard for magnetic particle inspection requires control of the crest factor and recommends avoiding current waveforms with a crest factor larger than three without documented evidence of detection effectiveness. Modern test bench units often use thyristor regulation of the magnetization current, which enables broad control ranges to generate an adequate magnetic field. A possible method of evaluation of magnetic field for magnetic particle inspection is to quantify the force effect on a detection particle. The cumulative force effect can be expressed as an impulse of force on a detection particle. The method of evaluation by an impulse of force implies that crest factor does not have a major effect if the impulse is controlled. This work contains a theoretical analysis of force in magnetic field generated by thyristor controlled currents. In the experimental part a comparison of indications generated by magnetic fields of different crest factorsis performed. The results of the experiment are in line with the theoretical analysis and show that it is the impulse that plays the major role in the formation of an indication and not crest factor.

On the Stability of Oscillatory Modes in an Oscillator Based on a Distributed Amplifier

  • Autoři: Filip, J., Suárez, A., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: IEEE Transactions on Microwave Theory and Techniques. 2023, 71(6), 2422-2438. ISSN 0018-9480.
  • Rok: 2023
  • DOI: 10.1109/TMTT.2022.3226454
  • Odkaz: https://doi.org/10.1109/TMTT.2022.3226454
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    An in-depth investigation of oscillation modes in an oscillator based on a distributed amplifier is presented. It shows that instability problems reported in previous papers are intrinsic to the circuit nonlinear dynamics. The undesired phenomena include discontinuous jumps when continuously varying the tuning voltage, quasi-periodicity, or two incommensurable selfgenerated oscillations, and nonuniqueness of the mode, meaning that the same frequency can be achieved by several combinations of tuning voltages. The numerical bifurcation analysis of the circuit reveals a complicated dynamical structure that explains the mechanisms leading to the reported undesired behaviors. Special attention is paid to the presence of complicated bifurcation scenarios leading to quasi-periodic behavior and a chaotic regime. The results of this theoretical investigation are confirmed by independent numerical simulations through time-domain integration and qualitatively predict the experimental observations. Then, a stabilization procedure based on the introduction of resistors is presented, evaluating its impact on the oscillation amplitude and the uniqueness of the desired oscillation modes obtained when tuning the bias voltages.

Time Multiplexing of Currents for Magnetic Particle Inspection

  • DOI: 10.1080/09349847.2022.2132336
  • Odkaz: https://doi.org/10.1080/09349847.2022.2132336
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This article concerns magnetization methods for detecting arbitrary oriented defects by magnetic particle inspection. The authors propose a new method of magnetization with omnidirectional detection ability requiring only a single-channel DC or AC power supply. The detection of all defects by the new method can be achieved during a single testing (spraying) cycle.

Automated Magnetic Field Evaluation for Magnetic Particle Inspection by Impulse

  • DOI: 10.1007/s10921-019-0615-4
  • Odkaz: https://doi.org/10.1007/s10921-019-0615-4
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new method of magnetic field evaluation for magnetic particle inspection is presented. Measurements show that a magnetic field value itself is not a sufficient predictor of detection ability. The evaluation method is based on a magnetic field measurement and the calculation of the impulse of magnetic force on a detection particle. Results are compared with commonly used gauges. Directions of sufficient field indicated by this novel method correspond with directions shown by standard gauges.

Experimental Setup For MPI Sensitivity Measurements: First Results

  • Autoři: Staněk, P., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: NDT in Progress 2019. Prague: Institute of Thermomechanics, AS CR, v.v.i., 2019. p. 71-74. ISBN 978-80-87012-72-7.
  • Rok: 2019
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    During the development process of MPI equipment it is very helpful to know the detection ability of the MPI process. Such an ability depends on material properties of the body under the test, applied magnetic field, defect shape and size, and detection particle properties. There is not enough information published, therefore in-house experiments are justified. This paper aims to present an experimental setup for MPI sensitivity measurement. The setup consists of four coils and two steel plates attached to the coils. The steel plates are magnetized by the flux generated by the coils. The coils are situated at the vertices of a square and the opposite coils are electrically connected in series therefore the setup can be fed by two independent current waveforms. These current waveforms generate two perpendicular magnetic field components on the plates so it is possible to generate arbitrary tangential magnetization on the surfaces of the steel plates. A standard shim gauge is placed on the steel plate in the middle of the coils. If the setup is fed by two sine waveforms of the same frequency and arbitrary phase shift, the tangential magnetization of the steel plates is elliptical polarized. The coils are fed from a pair of arbitrary-waveform generators amplified by a pair of power amplifiers. Using this setup the sensitivity of MPI can be measured for various input parameters. Measurement setup as well as first experimental results are presented in this paper.

The effect of higher harmonic components on MPI process

  • Autoři: Staněk, P., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: NDT in Canada Conference Proceedings. Canadian Institute for Non-destructive Evaluation, 2018. ISSN 2561-2050.
  • Rok: 2018
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Magnetic Particle Inspection (MPI) relies on magnetic forces driving small ferromagnetic particles. Such forces are caused by inhomogeneities (cracks) in ferromagnetic bodies perpendicular to magnetic field intensity. In order to detect defects in all possible directions it is essential to create rotating magnetic field tangential to the surface of the material under test. Such a field is required when the direction of discontinuities is unknown. The field polarization is usually tested by the Quantitative Quality Indicators (QQI). These indicators verify in which directions the field strength is adequate. If the field is indicated by QQI as a sufficient in all directions it is often called circular polarization, despite the fact it may not be really circular polarized. Measurements have shown that the polarization is elliptical at its best [1].The rotating magnetic field ideally consists of two perpendicular harmonic components of equal frequency and a ninety degrees mutual phase shift. In a presence of a nonlinear material (which is mostly the case) higher harmonics are generated. Moreover, heavy use of switching sources has changed power AC current waveform that it is no longer sinusoidal.Higher harmonic components are likely to change the magnetic field polarization nature. This paper investigates nonlinear effect and its impact on a polarization of magnetic field and MPI detection ability. It has been found that higher harmonic components may cause blind angles, eg. directions in which cracks are not likely to be detected. Examining the impulse of magnetic force affecting a particle, the total effect of higher harmonic components in MPI process is evaluated.

Experimental Gaussmeter for Circular Magnetization

  • Autoři: Staněk, P., prof. Ing. Zbyněk Škvor, CSc., Roxer, M.
  • Publikace: NDT in PROGRESS, IXth International Workshop of NDT Experts, Proceedings. Prague: Institute of Thermomechanics, AS CR, v.v.i., 2017. p. 104-107. ISBN 978-80-87012-63-5.
  • Rok: 2017
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Magnetic particle testing is a nondestructive process enabling detection of defects in ferromagnetic materials. In order to detect defects of all possible directions in one step a circular polarization of magnetic field is required. An experimental instrument providing for measurement of such fields is presented. It consists of a pair of hall magnetic sensors, a set of amplifiers and a controller with on-chip integrated A/D converters. This instrument brings an unprecedented insight to real time field measurement. In comparison with usually used gauges it provides precise quantified information about the magnetizing field. This technique is even faster and cleaner. The instrument provides fast response for both development and in-process verification.

Microstrip Open - Problematic Calibration Standard

  • DOI: 10.1109/ARFTG.2015.7162921
  • Odkaz: https://doi.org/10.1109/ARFTG.2015.7162921
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Microstrip open end (Open) applied as a calibration standard in frequency band up to 26 GHz was analyzed using CST Microwave Studio (CST). Arlon CuClad 233 with thickness 0.508mm was used for simulations. Different lengths of the microstrip lines in front of the Open were considered. Significant influence of the radiated field and the length of the microstrip line on the reflection coefficient magnitude of the standard in the order 0.01 was discovered. Physical explanation of the phenomenon is given .

Microwave interferometric method for metal sheet thickness measurement

  • DOI: 10.1109/ARFTG.2013.6579036
  • Odkaz: https://doi.org/10.1109/ARFTG.2013.6579036
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new microwave method capable of contactless thickness measurement of metal sheets with high resolution has been proposed. First experimental results in X-band are reported. The method is based on precise interferometric phase evaluation of a signal reflected step by step from two surfaces of a metal sheet whose thickness is to be measured. This is achieved using interference between the reflected and reference signals. Micrometer resolution at 10 GHz can be expected.

Simulation of Electromagnetic Field of a Fast Moving Target Close to Antennas

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Experiments have shown that Doppler signatures of a missile moving in a close vicinity of the antenna is quite complex. Experimentally obtained spectrograms exhibit clusters of Doppler frequencies instead of a single one. This is due to the fact that radial velocities differ significantly for different parts of the missile. Partial numerical simulations of this complex problem have been carried out for thin long fast-moving targets (wires). Simulation results compare well with measured Doppler signatures and enable better understanding of the problem and therefore improve the ability to distinguish dangerous targets from ordinary ones.

Precise microwave measurement of liquid level

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A simple interferometric waveguide setup has been developed, enabling for precise distance measurement of liquid level. Total reflection from the liquid surface is not necessary. For the most common case of lossy liquids, reflection phase must be determined properly. This may be accomplished by the use of a waveguide short for calibration. The setup was tested in measurement of water level. Resolution of the order of micrometers was achieved in X-band.

Contactless Distance Measurement Method

  • DOI: 10.1109/ARFTG77.2011.6034559
  • Odkaz: https://doi.org/10.1109/ARFTG77.2011.6034559
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new method capable of contactless distance measurement with high resolution has been proposed. The method is intended to measure distance differences smaller than one half of a wavelength. First experimental results are reported. The method is based on precise phase evaluation of signal reflected by the surface whose distance is measured. This is achieved using interference between the reflected and reference signals. Micrometer resolution at 10 GHz can be expected.

Metoda konečných diferenční v časové oblasti

  • Autoři: prof. Ing. Zbyněk Škvor, CSc., Pauk, L., Franek, O.
  • Publikace: Mikrovlnné struktury z netradičních materiálů. Brno: VUT v Brně, 2011. p. 43-76. ISBN 978-80-214-4419-5.
  • Rok: 2011
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Tato část práce se zabývá metodou konečných diferencí. Metoda je založena na tom, že původně spojitá hledaná funkce je nahrazena sadou diskrétních funkčních hodnot. Nehledá se tedy průběh funkce, ale sada jejích hodnot v uzlových bodech diskretizační sítě.

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.

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New Method Suitable for Relative Short Distance Measurement

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new method for relative short distance measurement of reflective surfaces was designed. The relative distance is derived from a frequency where two interfering coherent signals (one is reflected from the measured object, the second is a reference one) create a sharp signal minimum. The viability of the method was preliminary experimentally verified in X-band. Potential possibilities of the method were tested by software simulation. Sub-micron distance resolution in industrial applications can be supposed.

Evaluation and Correction of Cable Phase Stability in High Frequency Near-Field Measurement

  • DOI: 10.1109/COMITE.2008.4569887
  • Odkaz: https://doi.org/10.1109/COMITE.2008.4569887
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    In case of the near-field measurement, the radiated field by the measured antenna is received by two-dimensional scanner in defined points. During the process of the field scanning, the cable between the VNA and the scanner antenna is moved and its parameters are changed. This paper deals with the evaluation of the cable parameters changes. The dominant change is represented by the phase deviation of the cable transmission coefficient.The paper also proposes the method of the cable errors correction and evaluation of the correction method efficiency. The correction can be based on the full calibration at the reference plane of the scanner antenna feeding in all points of scanned field. The aforementioned approach is more time consuming than the proposed method, where the full calibration is performed in one selected point, while the correction of the cable parameters is based on the estimation based on the input impedance of the cable loaded by the scanner antenna.

Hidden Problems in Precise Calibration on Microstrip

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A study of calibration problems on microstrip with respect to interaction of electromagnetic fields around SMA to microstrip launcher and microstrip short was carried out in frequency band up to 26 GHz. Omni Spectra SMA to microstrip launcher, 50 Ω microstrip line on Arlon CuClad 223 0.508 mm thick substrate and microstrip shorts with reflective wall above the upper side of substrate as a calibration elements were used for simulations in CST Microwave Studio. Strong influence of dimensions of shorts and distance between the shorts and the launcher on simulated calibration data was observed. Reasonable dimensions of the short and the distance between the short and the launcher making possible correct precise calibration were determined.

Particle Accelerator Cavity Design

  • Autoři: Matlocha, T., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. p. 103-106. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper deals with the non-homogeneous quarter-wave rectangular TEM cavity parameters calculation. The cavity is modelled as a cascade of transmission lines and solved using impedance transformation and boundary conditions method. In fine, the resonant frequency, total power loss as a power efficiency ratio are calculated and discussed.

The UWB Amplifier 3.1-10.6 GHz

  • Autoři: Vancl, J., Sokol, V., Černý, P., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Proceedings of the 14th Conference on Microwave Techniques COMITE 2008. Praha: Československá sekce IEEE, 2008. p. 321-324. ISBN 978-1-4244-2137-4.
  • Rok: 2008
  • DOI: 10.1109/COMITE.2008.4569953
  • Odkaz: https://doi.org/10.1109/COMITE.2008.4569953
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The general principle of an ultra-wideband (UWB) amplifier design in the planar structure using the common available monolithic amplifier is proposed in this paper. The structure of the amplifier is designed in order to accomplish the conditions of the transmission of UWB impulses (flat gain and constant group delay over FCC approved frequency band) with a minimum distortion. The roll-of stage is used for the compensation of the declining gain and biasing of the monolithic amplifier. The demonstration of the distortion and the assessment criteria of distortion are also presented. The experimentally manufactured amplifier demonstrates a gain of 7.1?0.6 dB and a group delay variation of 7 ps from 4 to 9.3 GHz and 25 ps over the whole band.

Improved Evaluation of Planar Calibration Standards Using TDR Preselection Method

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Calibration and correction methods for Vector Network Analyzer (VNA) are based on the fundamental assumption of constant error model, which is independent of connected calibration standards and/or devices under test (DUT). Unfortunately, this assumption is not satisfied well for planar calibration standards fabricated by etching technology on soft substrates. An evaluation of the error etching technology on soft substrates. An evaluation of the error model is affected expecially with a variation of the manufacturing process and also with a reproducibillity of an assembly. In this paper, we propose error minimazation using selection of the best combination of available calibration standards based on time-domain reflection (TDR) measuerment. The proposed method was verified experimentally using short, open, load and thru (SOLT) standards fabricated on FR4 laminate substrate getting essential reduction of the measurement error in frequency range up to 15 GHz.

7 State PTP for Vector Network Analyzer

  • DOI: 10.1109/ARFTGS.2005.1500583
  • Odkaz: https://doi.org/10.1109/ARFTGS.2005.1500583
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new, 7 state switched perturbation two-port (PTP) for vector measurement based on scalar measurement only was designed and realized in microstrip structure using PIN diodes. The structure was experimentally tested by means of vector measurements of different impedances in frequency band with relative bandwidth of 2.5 octave. Good agreement with data obtained using a precise vector network analyzer was achieved.

A New Concept of PTP Vector Network Analyzer

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The novel 7-state PTP consists of switched elementary two ports composed from thru connection and serial and parallel RC, RL and R combinations connected to 50W microstrip line. It was designed for the frequency band 240-1600 MHz. The structure and the values of components of this PTP were optimized using the new test criteria. Corresponding quadratic planes are shown. The elements were chosen so that the individual quadratic planes were sufficiently different in the whole frequency band.

Assembly Influence on S-Parameters of Packaged Transistor

  • DOI: 10.1109/ARFTGS.2005.1500579
  • Odkaz: https://doi.org/10.1109/ARFTGS.2005.1500579
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A proper analysis of the assembly influence on small-signal parameters of packaged transistor has been done. The S-parameters differences caused by assembly change are computed using the standard method and three new proposed methods that exploit 3-D model of the transistor package. The differences, accuracy and suitability of these methods are discussed. The results were verified experimentally for particular packaged transistor in frequency range 45 MHz - 18 GHz.

Assembly Influence on the Small-Signal Parameters of a Packaged Transistor

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A detailed analysis of the assembly influence on the small-signal parameters of a packaged transistor is presented. A new method, based on 3D field simulation and mixed-mode scattering parameters approach is proposed. Differences in scattering parameters caused by assembly change are computed using the new proposed method and compared to the standard method based on admittance matrix. The differences, accuracy, error sources and suitability of both methods are discussed. Results are verified experimentally in microstrip line for two fundamental assembly change of a transistor in SOT 343 package in frequency range 45 MHz - 18 GHz.

Microwave Measurements of Radio Interference Filters

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Scalar and vector measurement methods for testing of multi-port radio interference filters for shielded chambers are designed. The method make possible to measure the filters in frequency band from DC-3 GHz. At the time being there is no acceptable standard for these multi-oort measurements.

Seven State PTP for Vector Network Analyzer

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new, 7 state switched perturbation two-port (PTP) for vector measurement based on scalar measurement only was designed and realized in microstrip structure using PIN diodes. The structure was experimentally tested by means of vector measurements of different impedances in frequency band with relative bandwidth of 2.5 octave. Good agreement with data obtained using a precise vector network analyzer was achieved.

A New concept of PTP Vector Network Analyzer

Analýza mikrovlnných struktur v časové oblasti

  • Autoři: Raida, Z., prof. Ing. Zbyněk Škvor, CSc., Pauk, L., Franěk, O., Láčík, J., Lukeš, Z., Tkadlec, R., Mottl, M.
  • Publikace: Brno: VUT v Brně, 2004. ISBN 80-214-2541-5.
  • Rok: 2004
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Kniha přináší informace o různých metodách řešení elektromagnetického pole v časové oblasti.

Assessment of Reference Planes Location for 3-D Components in Planar Structures

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    An appropriate reference plane location is the key issue of correct modeling of microwave circuits. A new method for the reference plane location assessment is proposed. The examples of stand-alone 3-D components as rell as for components in proximity of other 2-D or 3-D discontinuity. The reference plane location is strongly dependent on class of discontiuity laying in proimity of the component.

CAD pro vf techniku

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Sborník vzdělávacích a vědeckovýzkumných činností a nabídek. Praha: IEEE Czechoslovakia Section, 2004. p. 33. ISBN 80-86582-15-9.
  • Rok: 2004

First results of microwave measurement of broadband radio interference filters

Novel Broadband Vector Microwave Measurement Methods

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Multistate reflectometers represent an alternative to expensive network analyzers. This paper describes two particular instruments developed at the FEE CTU in Prague. One extends the classic scalar network analyzer by means of a special designed Perturbation Two-Port (PTP) while the second suggests a completely new circuitry for the detector as well as the linear variable part.

Time-Domain Modelling of Microwave Structures

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Proceedings of Workshop 2004. Praha: České vysoké učení technické v Praze, 2004. pp. 466-467. ISBN 80-01-02945-X.
  • Rok: 2004

Tunable Low Pass Coaxial Filter

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Microwave system designs have traditionally depended on passive circuit filter implementations, involving tradeoffs between filter performance and size. There are many types of filter constructions and also many design possibilities. Because of this situation, it has been decided at the department to incorporate into our new educational program at Laboratory of microwave optical and antennas techniques a new project called /Tunable Low-Pass Coaxial Filter/. The main purpose of this project is to familiarize students with the design procedures and realizations of the most typical coaxial microwave low pass filters, as well as with their measurement. This project is innovative in a technical and in a pedagogical sense: a teaching, learning and evaluating methodology.

6th International Student Conference on Electrical Engineering POSTER 2002

CAD pro vf techniku

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Sborník vzdělávacích a vědeckovýzkumných činností a nabídek katedry elektromagnetického pole FEL ČVUT. Praha: Československá sekce IEEE, 2003. p. 43. ISBN 80-86582-13-2.
  • Rok: 2003

Dual-State Reflectometer Based on Resistive Bridge

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    This paper presents a novel multistate reflectometer for automated reflection measurements. Along with theoretical considerations and details concerning design of the instrument, practical results are given. Based in a resistive bridge in conjunction with a 45-degree phase shifter, the instrument seems promising for wide-band measurements.

Evolutionary Design of Microwave Circuits

  • Autoři: Muller, T., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: COMITE 2003. Praha: IEEE Czechoslovakia Section, 2003. pp. 171-174. ISBN 80-86582-09-4.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Genetic and evolutionary algorithms have been used in microwave circuit design. These algorithms proved to be capable to contruct circuit tpology so that design goals were met. In this paper we propose an evolutionary (single population) algorithm for designing microwave circuits and present some of its results.

FDTD Stability: Critical Time Increment

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new approach suitable for determination of the maximal stable time increment for the Finite-Difference Time-Domain (FDTD) algorthm in common curvilinear coordinates, for general mesh shapes and certain types of boundaries is presented. The maximal time increment corresponds to a characteristic value of a Helmholz equation that is solved by a finite-difference (FD) method. it this method uses exactly the same discretization as the given FDTD method (same mesh, boundary conditions, order of precision etc.), the maximal stable time increment is obtained from the highest characteristic value. The FD system is solved by an iterative method, which uses only slightly altered original FDTD formulae. The Courant condition yields a stable time increment, but in certain cases the maximum increment is slightly greater.

Microwave-Circuit Optimization with Parallel Enhanced Fast Messy Genetic Algorithm (pefmGA)

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Fast messy genetic optimization is found suitable for complex microwave circuit design. Inrease in computation speed is achieved using several ordinary computers connected to a network. Calculations are running on background so that computers can be used for other purposes at the same time. Dynamic change of bounds, search space segmentation and gradient incorporation have significantly improved convergence rate. The new method has found global minimum in each run, while classic methods failed for some starting points.

Modern Methods of Vector Measurements

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The paper focuses on vector measurements exploiting multistate reflectometers. Since one of the most cricital components is the phase shifter, it suggest a technique that requires differential shift of only 45 degrees to achieve optimum location of the q-points. Preliminary experimental results given in the paper confirm our theoretical investigation.

On Radio Interference Filter Measurement

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A new measurement method for on site testing of multiport radio interference filters (RIF) on shielded chamber is designed. The method is based on scalar measurement only and makes possible a pessimistic estimate of the filters damping in frequency band from DC-3GHz. More than 120 dB dynamic of measurement can be expected. At the time being there is no acceptable standard for these multiport measurements.

Research of Selective Structures for Mobile Communication

  • Autoři: Pauk, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Proceedings of Workshop 2003. Praha: České vysoké učení technické v Praze, 2003. pp. 492-493. ISBN 80-01-02708-2.
  • Rok: 2003
  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    The project is focused on research of selective structures, above all on comb-line filters, which are frequently used in e.g. GSM multiplexers. Such filters are made of coupled transmission lines. A method suitable for computing parameters of coupled transmission lines (TEM mode) is presented. These parameters are necessary for analysis of the filters. These parameters are obtained from static capacities between line conductors. The method we use for computation of the capacities is precise and fast.

Wideband VIP Power Divider with Differential Output

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    A novel wideband VIP power divider with out of phase outputs was designed and experimentally verified. The phase difference 180°- 5°and the amplitude difference 0.8 dB of output signals were achieved in 4-26 GHz frequency band. Common ground of all coaxial ports is advantageous for application of the component in some differential measurements.

5th International Student Conference on Electrical Engineering POSTER 2001

A Multimedia Textbook of Electromagnetic Waves: An English Version

  • Autoři: Raida, Z., Černohorský, D., Gala, D., Goňa, S., Michálek, V., Navrátil, V., Nováček, Z., Otevřel, V., Poměnka, P., Šebesta, J., prof. Ing. Zbyněk Škvor, CSc., Urbanec, T., Froehling, K., Vandijek, B., Vanderstegen, G.
  • Publikace: WORKSHOP - Vzdělávací fórum - nabídka aktivit. Praha: ČVUT FEL, Katedra elektromagnetického pole, 2002. p. 3-8. ISBN 80-86582-07-8.
  • Rok: 2002

A Multimedia Textbook of EM Theory and Techniques

  • Autoři: Raida, Z., Černohorský, D., prof. Ing. Zbyněk Škvor, CSc., Nováček, Z.
  • Publikace: Automatika. 2002, 43(3-4), 163-168. ISSN 0005-1144.
  • Rok: 2002

AMOS - Autonomous Student Work Support

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: WORKSHOP - Vzdělávací fórum - nabídka aktivit. Praha: ČVUT FEL, Katedra elektromagnetického pole, 2002. p. 27-28. ISBN 80-86582-07-8.
  • Rok: 2002

CAD pro VF techniku

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: WORKSHOP - Vzdělávací fórum - nabídka aktivit. Praha: ČVUT FEL, Katedra elektromagnetického pole, 2002. p. 55. ISBN 80-86582-07-8.
  • Rok: 2002

FDTD Stability: Critical Time Increment

  • Autoři: Pauk, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop CAD CAE'2002. Praha: IEEE Czechoslovakia Section, 2002. p. 13-16. ISBN 80-86582-05-1.
  • Rok: 2002

Programové vybavení používané na katedře elektromagnetického pole ČVUT FEL K NÁVRHU ANTÉN, VF A MIKROVLNNÝCH OBVODŮ

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: WORKSHOP - Vzdělávací fórum - nabídka aktivit. Praha: ČVUT FEL, Katedra elektromagnetického pole, 2002. p. 29-38. ISBN 80-86582-07-8.
  • Rok: 2002

Scalable Parallel Optimisation using Fast Messy Genetic Algorithm

  • Autoři: Kostka, P., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop CAD CAE'2002. Praha: IEEE Czechoslovakia Section, 2002. pp. 1-4. ISBN 80-86582-05-1.
  • Rok: 2002

Scalable Parallel Optimisation Using Fast Messy Genetic Algorithm

  • Autoři: Kostka, P., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: 2002 Asia-Pacific Microwave Conference Proceedings. Tokyo: IEICE, Institute of Electronics, Information and Communication Engineers, 2002. pp. 309-312.
  • Rok: 2002

30-th Anniversary of the Department of Electromagnetic Field at CTU Prague

Active Microwave and millimeterwave Resonator

Active Resonator

An Explicit Method to Calibrate Multistate Reflectometer

Analysis of the Stripline Interdigital Filters

  • Autoři: Černý, P., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: COMITE 2001. Praha: IEEE Czechoslovakia Section, 2001. pp. 159-162. ISBN 80-902417-9-4.
  • Rok: 2001

Antenna Laboratory

Arbitrary Q-Factor Dielectric Resonator

Calibration of E-Field Probe for SAR Measurement in Lossy Liqui

  • Autoři: Dlouhý, R., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Proceedings of Euroepan Conference on Wireless Technology - ECWT. London: CMP Europe Ltd, 2001. ISBN 0-86213-149-1.
  • Rok: 2001

Calibration of E-Field Probe for SAR Measurement in Lossy Liquid

  • Autoři: Dlouhý, R., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Conference Proceedings - 31st EuMC 2001. London: CMP Europe Ltd, 2001. pp. 109-112. ISBN 08-62-13148-0.
  • Rok: 2001

Comb-Line Filter Analysis

  • Autoři: Pauk, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: COMITE 2001. Praha: IEEE Czechoslovakia Section, 2001. pp. 233-236. ISBN 80-902417-9-4.
  • Rok: 2001

Contribution to the Multistate Reflectometer Calibration

New Measurement Method for Characteristic Impedance Determination

Parallel Optimization Machine Using a Genetic Algorithm - Preliminary Study

  • Autoři: Kostka, P., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: COMITE 2001. Praha: IEEE Czechoslovakia Section, 2001. pp. 181-184. ISBN 80-902417-9-4.
  • Rok: 2001

SMITH CHART FOR WINDOWS - program pro CAD vysokofrekvenčních obvodů

  • Autoři: Kostka, P., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop CAD&CAE'2001. Praha: IEEE Czechoslovakia Section, 2001. pp. 24-26. ISBN 80-86582-04-3.
  • Rok: 2001

Stability of FDTD in Curvilinear Coordinates

  • Autoři: Pauk, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Poster 2001. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2001. pp. NS31.
  • Rok: 2001

Stability of FDTD in Curvilinear Coordinates

Time-Domain Modeling of Microwave Structures

  • Autoři: Raida, Z., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: COMITE 2001 - Grant Forum. Praha: Československá sekce IEEE, 2001. pp. 8. ISBN 80-86582-02-7.
  • Rok: 2001

A Tool for Microwave CAD Education

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: MIKON 2000 - XIII International Conference on Microwaves, Radar and Wireless Communications. Warsaw: Telecommunication Research Institute, 2000. p. 499-501. ISBN 83-906662-0-0.
  • Rok: 2000

AMOS - podpora samostatné práce a distančního vzdělávání prostřednictvím internetu

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Přidělování úloh studentům a vyhodnocování jejich odpovědí je automaticky prováděno systémem AMOS.

AMOS Computer Aided Education System Enabling for Autonomous Work and Assessment through Internet

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Proceedings of Workshop 2000. Praha: České vysoké učení technické v Praze, 2000. pp. 165. ISBN 80-01-02229-3.
  • Rok: 2000

AMOS Interactive System - an Internet Tool Supporting Autonomous Work

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Proceedings of the 11th Annual Conference of the EAEEIE. Ulm: Mikrowellentechnik der Universitaet Ulm, 2000. pp. 231-234. ISBN 3-00-005965-2.
  • Rok: 2000

Experimental Distributed Oscillator in the GigaHertz Region

  • Autoři: prof. Ing. Zbyněk Škvor, CSc., Divina, L.
  • Publikace: Proceedings of Workshop 2000. Praha: České vysoké učení technické v Praze, 2000. pp. 175. ISBN 80-01-02229-3.
  • Rok: 2000

FDTD vs. "Mode Matching" Method Comparison - Coaxial Discontinuity Analysis

  • Autoři: Pauk, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Proceedings of Workshop 2000. Praha: České vysoké učení technické v Praze, 2000. pp. 216. ISBN 80-01-02229-3.
  • Rok: 2000

Inductance of Short Wires

Microwave Vector Measurement

Pohled na stabilitu metody FDTD

  • Autoři: Pauk, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop CAD&CAE 2000. Prague: Czechoslovakia Section IEEE, 2000. pp. 45. ISBN 80-902417-6-3.
  • Rok: 2000

Výzkum, moderní technologie a praxe

WinMIDE - program pro CAD VF obvodů

  • Autoři: Kostka, P., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop CAD&CAE 2000. Prague: Czechoslovakia Section IEEE, 2000. pp. 46-48. ISBN 80-902417-6-3.
  • Rok: 2000

A 0.41-4.2 GHz Microwave VCO

  • Autoři: Ali, W., Aitchison, C., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Postgraduate Research in Electronics, Photonics. Manchester: University of Manchester, 1999. pp. 236-237.
  • Rok: 1999

Evaluation of PTP Measured Data

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: 9th International Czech-Slovak Scientific Conference Radioelektronika 99. Brno: VUT v Brně, 1999. pp. 265-266. ISBN 80-214-1327-1.
  • Rok: 1999

FDTD vs. MODE MATCHING Method Comparison on an Example of Coaxial Discontinuity Analysis

  • Autoři: Pauk, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop CAD&CAE'99. Prague: Czechoslovakia Section IEEE, 1999. pp. 5-7. ISBN 80-902417-4-3.
  • Rok: 1999

Interactive Internet Support of Project Tasks "AMOS"

Klasické metody optimalizace

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Analýza a optimalizace mikrovlnných struktur. Brno: VUTIUM Press, 1999. p. 151-168. ISBN 80-214-1512-6.
  • Rok: 1999

Metoda přímek

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Analýza a optimalizace mikrovlnných struktur. Brno: VUTIUM Press, 1999. p. 201-218. ISBN 80-214-1512-6.
  • Rok: 1999

Microstrip Coupling Structure for Tight Coupling

Mikrovlnná měřicí techníka - část 3. - Součanost a perspektivy radiové komunikace

Perspektivy mikrovlnné techniky

Počítačem podporovaný návrh (CAD) vysokofrekvenčních obvodů

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: 1. seminář "Spolupráce vysokých a středních škol" (výchova technické inteligence v oblasti elektrotechniky). Prague: Czechoslovakia Section IEEE, 1999. pp. 8-12. ISBN 80-902417-5-1.
  • Rok: 1999

Počítačem podporovaný návrh obvodu - Současnost a perspektivy radiové komunikace

Počítačem podporovaný návrh vysokofrekvenčních obvodů - část 4. CAD - Současnost a perspektivy radiové komunikace

Radiokomunikace a mikrovlny - Současnost a perspektivy radiové komunikace

A Decade Bandwith Distributed Oscillator

  • Autoři: Ali, W., Aitchison, C., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: EDMO 98 - 6th IEEE International Workshop on High Performance Electron. Manchester: University of Manchester, 1998. pp. 189-193.
  • Rok: 1998

A Novel Vector Network Analyzer

AMOS Network Computer Aided Education System

Calibration of the PTP Vector Network Analyzer

Co-axial Structure Analysis

  • Autoři: Pauk, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop 98. Praha: České vysoké učení technické v Praze, 1998. pp. 249-250.
  • Rok: 1998

Cost-effective Vector Measurement

Design and Testing of Anechoic Chambers for Antenna Measurement

Distributed Oscillator at 4 GHz

  • Autoři: Divina, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: IEEE Transactions on Microwave Theory and Techniques. 1998, 46(12), 2240-2244. ISSN 0018-9480.
  • Rok: 1998

Less Common TEM Transmission Lines

  • Autoři: Bezouška, Z., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop 98. Praha: České vysoké učení technické v Praze, 1998. pp. 247-248.
  • Rok: 1998

Novel Vector Network Analyzer

Podpora samostatné práce studentů prostřednictvím sítě INTERNET

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Seminár katedier z oblasti teoretickej elektrotechniky Českej a Slovenskej republiky. Bratislava: STU v Bratislave, FEI, 1998. pp. 41-42.
  • Rok: 1998

Some Aspects of Library Element Implementation

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop CAD&CAE'98. Praha: ČVUT FEL, Katedra elektromagnetického pole, 1998. pp. 48-49. ISBN 80-902417-2-7.
  • Rok: 1998

TEM Line Impedance Calculation

  • Autoři: prof. Ing. Zbyněk Škvor, CSc., Bezouška, Z.
  • Publikace: Radioelektronika 98. Brno: VUT v Brně, 1998. pp. 479-482. ISBN 80-214-0983-5.
  • Rok: 1998

The Distributed Oscillator at 4 GHz

  • Autoři: prof. Ing. Zbyněk Škvor, CSc., Divina, L.
  • Publikace: 1998 IEEE MTT-S International Microwave Symposium Digest. Piscataway: IEEE, 1998. pp. 865-868. ISBN 0-7803-4472-3.
  • Rok: 1998

Boundary Conditions and FDTD

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Radioelektronika '97. Bratislava: STU v Bratislave, 1997. pp. 252-255. ISBN 80-227-0943-3.
  • Rok: 1997

Combined Microstrip Antenna Arrangements

FDTD Analysis of Coaxial Discontinuities

  • Autoři: Pauk, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: COMITE 1997. Pardubice: Univerzita Pardubice, 1997. pp. 279-281. ISBN 80-902417-0-0.
  • Rok: 1997

HP 8410-PC Controlling System and PTP Vector Analyzer

Microwave Transistor Catalogue Data vs. Measured Data

Microwave Transistor Data: Catalogue vs. Measurement

MTR-2 Correction Method for FET Measurements Based on a 4-Port Error Model Including Crosstalks

On the Measurement of Material Dielectric Properties

Optimalizace v návrhu vysokofrekvenčních obvodů

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop CAD and CAE 97. Praha: ČVUT FEL, Katedra elektromagnetického pole, 1997. pp. 43-44. ISBN 80-902417-1-9.
  • Rok: 1997

Patch Antennas with Reduced Dimensions

Planar Antenna Analysis Using TLM

Tunable Oscillator Based on a Distributed Amplifier

  • Autoři: Divina, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop 97. Praha: České vysoké učení technické v Praze, 1997. pp. 897-898.
  • Rok: 1997

Výpočet impedancí vedení netradičních průřezů

  • Autoři: Bezouška, Z., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop CAD and CAE 97. Praha: ČVUT FEL, Katedra elektromagnetického pole, 1997. pp. 39-42. ISBN 80-902417-1-9.
  • Rok: 1997

An Inhomogeneous Coupled Lines DC Block

  • Autoři: prof. Ing. Zbyněk Škvor, CSc., Huynen, I.
  • Publikace: XIth International Microwave Conference - MIKON '96. Warsaw: Telecommunication Research Institute, 1996. pp. 152-156.
  • Rok: 1996

Mide a obecné impedance zdrojů a zátěží

On the Solution of Inhomogeneous Coupled Lines

Vector Measurement With Scalar Analyzer

Vector Measurement with Scalar Only Analyzer

A Novel Method of Vector Measurement Using Scalar Analyzer

A Novell Method of Vector Measurement Using Scalar Analyzer Only

Computer Aided Determination of Electromagnetic Pollution

  • Autoři: Kokeš, P., Musil, J., prof. Ing. Zbyněk Škvor, CSc., Tomandl, J., Bartušek, J.
  • Publikace: MITEKO 95. Pardubice: HTT Tesla, 1995. pp. 23-24.
  • Rok: 1995

Correction Method for Non-Coaxial Test Fixtures with Limited Number of Calibration Elements

Electromagnetic Exposure of Mobile-Telephone Users

Experimental Distributed Amplifier Oscillator

Experimental Verification of a Distributed Amplifier Oscillator

  • Autoři: Divina, L., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: 25th EuMC 1995 Conference Proceedings. Kent: Nexus House, 1995. p. 1163-1167. ISBN 1-899919-15-5.
  • Rok: 1995

HIGH Frequency Lines - program pro výpočty na vysokofrekvenčních vedeních

  • Autoři: Bartušek, J., prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Workshop CAD&CAE 1995. Praha: ČVUT FEL, Katedra elektromagnetického pole, 1995. pp. 15-18.
  • Rok: 1995

Interactive Smith Chart and Transmission Line Analyzer/Synthesizer

On the Impedance of Parallel Plate Guides

Supressing Redundant Solutions Obtained by the Method of Lines

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Proceedings of the Second Japanese-Czech-Slovak Joint Seminar on Applied Electromagnetic Field in Materials. Kyoto: Japan Society for Applied Electromagnetic Field, 1995. pp. 180-190. ISSN 0919-4452.
  • Rok: 1995

Vector Measurement Using Scalar Sensor Only

Vector Measurement with Scalar Analyzer

Vector Measurement with Slalar Analyzer

Calculation of a Power Field in Electric Glass Melting Furnace

Modernization of PhD. Studies in Radioelectronics

New Correction Methods for Non-coaxial Test Fixtures

Supressing Redundant Solutions by the Method of Lines

  • Autoři: prof. Ing. Zbyněk Škvor, CSc.,
  • Publikace: Journal of the Japan Society on Applied Electromagnetics in Materials. 1994, 3(Sup), 341-347. ISSN 0919-4452.
  • Rok: 1994

Využití podpory pro DE-Embedding v programu Mide

Calculation of a Power Field in Lectric Glass Melting Furnace

Computer Aided Design of Radiofrequency and Microwave Circuits

NAF - program pro návrh analogových frekvenčních filtrů

New Correction Methods for Non-coaxial Test Fixtures

Zesilovače s rozprostřenými parametry

A Novell Electronically Tunable Distributed Oscillator

Evolutionary Design of Microwave Circuits

  • Pracoviště: Katedra elektromagnetického pole
  • Anotace:
    Genetic and evolutionary algorithms have been used in microwave circuit design. These algorithms proved to be capable to construct circuit topology so that design goals were met. In this paper we propose an evolutionary algorithm for designing microwave circuits and present some of its results.

Za stránku zodpovídá: Ing. Mgr. Radovan Suk