A refined two-step algorithm for high resolution spaceborne SAR with squinted sliding spotlight mode

Spaceborne squinted sliding spotlight synthetic aperture radar (SAR) can achieve high-resolution image with well flexibility. However, traditional imaging algorithm cannot focus its data, as the serious coupling between the range and the azimuth and the azimuth spectral aliasing problem. To process the data, a refined two-step algorithm is proposed in this paper. Firstly, the linear range cell migration correction (LRCMC) and De-rotation are adopted to solve the azimuth spectral aliasing problem. Then the data is focused with a modified wavenumber domain algorithm (WDA). Also, the azimuth nonlinear chirp scaling (NCS) method is used to solve the limited depth-of-azimuth-focus (DOAF) problem. At last, the geometric correction is adopted to correct the geometrical distortion. The computer simulation results verify the validity of the proposed imaging algorithm.