Tracking System using Fixed Beamwidth Electronics Scanning

Abstract — In several applications for tracking systems, the scanning rate is considered a critical factor. The mechanical steering appears to be impractical for its slow rate and space consumption so the need for electronics scanning appears clearly. But unfortunately, the electronic scanning suffer from beamwidth broadening and gain variations with steering angles. In this paper, a fixed beamwidth electronic scanning algorithm is proposed. The proposed algorithm is based on synthesizing sets of excitation coefficients to direct the main beam at some scanning angles. The synthesis takes into consideration the fixation of the beamwidth at these angles. The main concept is to enlarge the antenna array aperture size to a predefined optimum value to get a fixed beam in all the scanning angles. The synthesis of the excitation coefficients is done using a scheme based on the method of moments due to its accuracy in solving such problems. The optimum spacing between elements is determined using the genetic algorithm. One of the main advantages of the proposed algorithm is the applicability of synthesizing multibeam antenna array of fixed beamwidths using the superposition principle. The system is already built and tested with conventional microstrip antenna array elements where good tracking results are observed