Predistortion Arithmetic on Low Sidelobe Pulse Compression Signal for Spaceborne Weather Radar

Pulse compression with very low sidelobes is one of challenges in the design of spaceborne weather radar. To detect the weak echoes of clouds occurring near the strong echoes of sea surface, sidelobe performance below -60 db is needed in the pulse compression system. To achieve such low sidelobes, high SNR and linearity are required in the radar system. But in spaceborne radar system, the transmitter often works at saturation point to get high output power and high efficiency. So a successive over relaxation (SOR) iterative method of digital predistortion is applied here to ensure the sidelobe performance and high efficiency of PA. A test system based on RFPA, ESG and VSA is carried out to verify and optimize the predistortion arithmetic.