Transmit antenna pattern synthesis for secondary surveillance radar

A new method of transmit pattern synthesis for secondary surveillance radar (SSR) is presented. This method is concerned with an active phased array antenna, in order to eliminate the interference introduced by the interrogation sidelobe signal which triggers the transponder mounted on the airplane. A cosine on pedestal excitation for the aperture distribution is used to synthesize the desired directional pattern, which is used to transmit the P₁ and P₃ pulse for interrogation. Using the stationary phase method, the phase function over the aperture on the specified aperture amplitude distribution is obtained and the desired pattern to transmit the P₂ pulse is synthesized for interrogation sidelobe suppression (ISLS). The antenna and relevant equipment which transmits only the P ₂ pulse is saved