2003/1

Browse

Recent Submissions

Now showing 1 - 5 of 11
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Site Diversity Gain Estimated from Rain Rate Records
    (Společnost pro radioelektronické inženýrství, 2003-04) Fiser, Ondrej
    The site diversity is used to mitigate the rain attenuation on satellite links. The attenuation is estimated through the rain rate-rain attenuation conversion based on the Assis-Einloft physical model in this study. Through the comparison of instantaneous attenuations at two receiving sites the site diversity gain is estimated. Examples of rain rate measurements in the Czech Republic followed by the site diversity gain estimation are added. This gain is greater on west-east situation of receiving sites achieving 10 dB on 0.01% exceedance level/100 km.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Optimized State Model of Piecewise-Linear Dynamical Systems
    (Společnost pro radioelektronické inženýrství, 2003-04) Pospisil, Jiri; Kolka, Zdenek; Hanus, Stanislav; Michalek, Vaclav; Brzobohaty, Jaromir
    The conditions for an optimized design of the second dynamical system having low eigenvalue sensitivities are directly derived. Their more general form is in accordance with the previous results obtained by using linear topological conjugacy.