2006/4

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    Methods for High Power EM Pulse Measurement
    (Společnost pro radioelektronické inženýrství, 2006-12) Drexler, Petr; Fiala, Pavel
    There are some suitable methods for the measurement of ultra-short solitary electromagnetic pulses that can be generated by high power pulsed generators. The measurement methods properties have to correspond to the fact whether we want to measure pulses of voltage, current or free-space electromagnetic wave. The need for specific measurement methods occurred by the development of high power microwave pulse generator. Applicable methods are presented in this paper. The method utilizing Faraday\'s induction law allows the measurement of generated current. For the same purpose the magneto-optic method can be utilized, with its advantages. For measurement of output microwave pulse of the generator the calorimetric method was designed and realized.
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    Modeling and Optimizing Antennas for Rotational Spectroscopy Applications
    (Společnost pro radioelektronické inženýrství, 2006-12) Lukes, Zbynek; Lacik, Jaroslav; Raida, Zbynek
    In the paper, dielectric and metallic lenses are modeled and optimized in order to enhance the gain of a horn antenna in the frequency range from 60 GHz to 100 GHz. Properties of designed lenses are compared and discussed. The structures are modeled in CST Microwave Studio and optimized by Particle Swarm Optimization (PSO) in order to get required antenna parameters.
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    Geometrical Configuration of Cabling as Factor Influencing the Reproducibility of EMC Immunity Tests
    (Společnost pro radioelektronické inženýrství, 2006-12) Hallon, Jozef; Kovac, Karol; Szolik, Imrich
    The paper deals with analysis of the influence of geometrical configuration of device cabling upon voltages induced in cable interfaces. The analyzed properties are the cable height and the cable length for common mode disturbance, and the loop width for differential mode disturbance. The analysis is solved both by analytical calculation and by numerical simulation. Achieved results are compared mutually as well as with results obtained by measurements performed according to standardized procedures. Finally the analyzed parameters are ordered in correspondence of their importance for objectivity and reproducibility of immunity tests against electromagnetic field.
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    Multipath Propagation of UWB Through-Wall Radar and EMC Phenomena
    (Společnost pro radioelektronické inženýrství, 2006-12) Schejbal, Vladimir; Cermak, Dusan; Nemec, Zdenek; Pidanic, Jan; Konecny, Jiri; Bezousek, Pavel; Fiser, Ondrej
    The UWB (ultra wide band) radar output signals can be substantially affected due to electromagnetic wave propagation through obstacles (such as walls) and multipath effects, too. Multipath effects are analyzed and simulated numerically for various cases with several antenna heights and distances. Delays (due to propagation through walls and various paths of direct and reflected rays) and the ringing (similar to UWB propagation through wall) can be clearly observed and analyzed. Moreover, frequency spectra analyses can demonstrate both UWB interferences and susceptibility from electromagnetic compatibility (EMC) viewpoint.
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    Electromagnetic Compatibility of Matrix Converter System
    (Společnost pro radioelektronické inženýrství, 2006-12) Lettl, Jiri; Fligl, Stanislav
    The presented paper deals with matrix converters pulse width modulation strategies design with emphasis on the electromagnetic compatibility. Matrix converters provide an all-silicon solution to the problem of converting AC power from one frequency to another, offering almost all the features required of an ideal static frequency changer. They possess many advantages compared to the conventional voltage or current source inverters. A matrix converter does not require energy storage components as a bulky capacitor or an inductance in the DC-link, and enables the bi-directional power flow between the power supply and load. The most of the contemporary modulation strategies are able to provide practically sinusoidal waveforms of the input and output currents with negligible low order harmonics, and to control the input displacement factor. The perspective of matrix converters regarding EMC in comparison with other types of converters is brightly evident because it is no need to use any equipment for power factor correction and current and voltage harmonics reduction. Such converter with proper control is properly compatible both with the supply mains and with the supplied load. A special digital control system was developed for the realized experimental test bed which makes it possible to achieve greater throughput of the digital control system and its variability.