2003/1

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    New Second-Order Optimized Filter Design
    (Společnost pro radioelektronické inženýrství, 2003-04) Pospisil, Jiri; Kolka, Zdenek; Hanus, Stanislav; Dostal, Tomas; Brzobohaty, Jaromir
    Starting from the piecewise-linear (PWL) autonomous dynamical system optimized from the eigenvalue sensitivities viewpoint the corresponding optimized non-autonomous linear (single-input single-output) system is derived. Such a design procedure gives the possibility to obtain minimum eigenvalue sensitivities with respect to the change of the individual model parameters also for non-autonomous linear systems. Two examples of the system having the complex conjugate poles and zeros, i.e. the optimized second-order band-reject and all-pass filter design, are shown.
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    Refractive Index Measurement at TV Tower Prague
    (Společnost pro radioelektronické inženýrství, 2003-04) Grabner, Martin; Kvicera, Vaclav
    Propagation related parameters are used for design and frequency planning of microwave networks. Atmospheric refractive index is the important parameter that influences the propagation of electromagnetic waves during so-called "clear sky" conditions. The refractive index measurement, which was launched in TESTCOM, is presented in this paper. Some statistical characteristics and their utilization are introduced.
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    Generation of the Narrow Band Digital Modulated Signals Using Quadrature Digital Upconverter
    (Společnost pro radioelektronické inženýrství, 2003-04) Kovar, Pavel
    The paper deals with the modern approach to generation of digital modulated signals at intermediate frequency in digital way. The common digital modulator is based on analogue Quadrature modulator. The modern VLSI integrated circuits enable to implement this signal processing method in digital form. Analog and digital approaches are compared in this document. The measurement of narrow band D8PSK modulation signal generated by Quadrature Digital Upconverter is presented in this paper.
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    Comparison of CAD Formulas, Method of Moments and Experiments for Rectangular Microstrip Antennas
    (Společnost pro radioelektronické inženýrství, 2003-04) Schejbal, Vladimir; Raida, Zbynek; Novacek, Zdenek
    Calculations of several cases for rectangular microstrip patch antennas using more accurate cavity model have been compared with the conventional cavity calculations, expressions generated by curve fitting to full wave solutions and method of moments. Calculated as well as experimental values have been studied for different thickness, patch sizes and substrate materials with different permittivities and losses.
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    Resistively Loaded Dipole Characteristics
    (Společnost pro radioelektronické inženýrství, 2003-04) Hajach, Peter; Hartansky, Rene
    Resistively loaded dipole is very often used to measuring the electromagnetic field in EMC testing. The dipole is a traveling wave antenna, where its resonance is eliminated. The paper includes the computation of the current distribution and radiation pattern of this dipole. The characteristics were obtained by moment method, Hallen method and Wu-King method. The unique modification of presented methods has been made. The comparison of used methods has been presented in paper conclusions.