Computer Aided Design Of Radar System SpatialStructures

Abstract

One of the most important problems that must be solved while planning the arrangement of radiolocation stations is that of placement in order to ensure the early detection of flying objects and to prevent work disturbances. Information about where to place a disturbance transmitter or a radio recognizing station in order to efficiently disturb the work of radio systems is crucial. Because of the special nature of radio wave propagation, the efficiency of disturbance or rather the efficiency of detection depends not only on the distance between the receiving station and the disturbance transmitter but also on the form and coverage of the surface on the propagation road. Research of various models of radio wave propagation has been conducted in the MUT. Such models are the main part of the software used to predict the useful and disturbance range of sources of electromagnetic radiation. Another important problem connected with the specification of the possibility of compatible functioning or proper disturbance is the necessity to have full information about the resistance of the device and various other types of emission on disturbance. 1 The procedure of calculating stations’ range The basic parameters, which are important while planning the arrangement of a radiolocation device, are the useful range and the disturbance range. In case of disturbance devices it is necessary to calculate the disturbance range, which sets the minimal distance between the station emitting the disturbance signal and the disturbed receiver. The distance should prevent the receiver from receiving the useful signal correctly. High Performance Structures and Materials II, C.A. Brebbia & W.P. De Wilde (Editors) © 2004 WIT Press, www.witpress.com, ISBN 1-85312-717-5 An important parameter used for calculating the disturbance range is the protection coefficient [4]. The idea of „quality criteria” is based on the existence of a specified limiting value of relation of the useful signal range to the disturbance range ( )P I S , which allows receiving the message correctly. The value of the coefficient depends on the kind of useful and disturbance signal and is a function of offset of the disturbance signal from the useful signal. An example of the course of the safety coefficient for a useful signal emitted by the aviation system RSBN and disturbance signal emitted by the base station of the GSM system is shown in following figure. -45 -40 -35 -30 -25 -20 -15 -10 -3 -2,4 -1,8 -1,2 -0,6 0 0,6 1,2 1,8 2,4 3 offset f [MHz] co ef fic ie nt p ro te ct iv e p