A novel sum-difference side lobe suppression array antenna

A novel sum-difference side lobe suppression array antenna applied in secondary surveillance radar (SSR) system is designed in order to solve the suppression problem with the traditional sum-difference array antenna. The antenna consists of front array, back element antenna, beam forming network and RF cables. The difference beam is formed by front array and back element antenna, of which the amplitudes and phases is optimized by genetic algorithm. By using this method, a good coverage of the side lobe of the sum beam is obtained in operating bandwidth. The simulation and test results of the antenna show that the characteristics of the sum beam is the same as the conventional sum-difference antenna, meanwhile, the difference beam can achieve 100% coverage in azimuth of the side lobe of the sum beam with a relative band width of 13.2%.