The analysis of monopulse passive direction finding techniques

Electronic warfare operations involve three basic missions including electronic attack, electronic defense and electronic support measures. Electronic support measures are utilized to provide intelligence to command and control mechanism or the friendly troops, to generate valuable information, kept confidential, up to date and available in order to use both in attack and in defense operations in the event of war. Radar warning receiver systems, used to generate critical information about presence, distance, location and direction of target, is one of the electronic support measures. These systems use many different direction finding techniques for finding direction of target. In this thesis, amplitude comparison and phase comparison algorithms of monopulse direction finding techniques are analyzed. Direction finding performance is examined at different SNR and frequencies using amplitude and phase comparison algorithms for 4, 6 and 8 sector antenna structures. Phase comparison technique can perform more accurate estimation of direction of arrival compared to amplitude comparison technique. However, in this technique, direction ambiguities increasing error of estimation of direction of arrival are emerging at high frequencies. The causes of consisting ambiguities were explained and solution methods were recommended for these ambiguities because of phase comparison technique. Moreover, direction estimation is analyzed with less antenna using fractured antenna structures for specific search interval and direction estimation is achieved with low error rates. Different antenna placement geometries are tested at different SNR and frequencies in order to decrease the number of antenna and the result are introduced. Beside these, system mismatch errors caused by the nature of electronic system was analyzed severaly for amplitude and phase comparison techniques, considering the situation that antennas look in target with different elevation angle, the effect of consisting elevation angle errors on direction finding performance was analyzed.