Contents I. Introduction
Spaceborne weather radar can measure detailed structure of rainfall on a global scale and provide information about the heat and water transferring through the atmosphere. The Tropical Rainfall Measuring Mission (TRMM) satellite developed by NASA and JAXA has demonstrated the feasibility of measuring rainfall from space [1]. To detect the weak echoes of clouds occurring near the strong echoes of sea surface, range sidelobe performance below-60db is needed in the pulse compression system [2]. So high linearity and low noises 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. The nonlinear effect of power amplifier will degrade the sidelobe performance and the weak echoes of clouds will be submerged by range sidelobes of the echoes of the sea surface. In this paper, a new sidelobe suppression arithmetic in frequency domain to achieve-70dB sidelobe performance is introduced and an iterative method of digital predistortion is carried out to compensate the distorted signals. Figure 1 shows the block diagram of the precompensation process of a spaceborne weather radar.
