结合直达波补偿的星地双站SAR滑动聚束模式频域成像算法

星地双站合成孔径雷达以星载系统为机会照射源，地面接收机接收直达波和散射波信号进行同步和成像处理。介绍了星地双站合成孔径雷达系统结构，对基于直达波进行距离向脉冲压缩后的信号调频率、距离徙动以及二维频谱的空变性进行了分析。在此基础上，运用方位向预处理过程、直达波补偿以及非线性Chirp Scaling算法，提出了适合该模型的频域成像算法，并通过点目标仿真验证了该成像算法的有效性和性能。HITCHHIKER星地双站合成孔径雷达系统实测数据进一步验证了该成像算法的有效性。
In fixed-receiver bistatic SAR (synthetic aperture radar), the spaceborne SAR was used as the illuminator. The direct-path signal and the backscattering echo were sampled, synchronized and focused by the receiver. The geometry of fixed receiver bistatic SAR was introduced. After the direct-path signal was used as reference signal for range match filtering, the spatial variation of chirp rate, range cell migration and two-dimensional spectrum were analyzed. Based on azimuth preprocessing, direct-path signal compensation and nonlinear Chirp Scaling imaging algorithm, a new focusing algorithm was presented. Simulation results of point targets were presented to validate the feasibility and efficiency of the proposed method. This algorithm was also validated by the measured data of the HITCHHIKER system.