Modified Range-Doppler Algorithm for High Squint SAR Echo Processing

A modified range-Doppler algorithm (M-RDA) for processing high squint synthetic aperture radar (SAR) echoes is proposed in this letter. Unlike the original RDA, the M-RDA directly corrects the range cell migration in the range frequency domain without interpolation, which greatly enhances its computational efficiency. When analyzing a high squint SAR echo signal, the approximation of the distance between the SAR antenna and the scene of interest leads to error in azimuthal compression. To address this problem, a fourth-order phase model is considered in the proposed algorithm to achieve accurate azimuthal compression. Finally, geometry correction is performed to obtain the final focused SAR images. The simulation results show that the proposed algorithm can process high squint SAR echoes effectively.