Novel full aperture imaging algorithm for highly squinted TOPS SAR

Due to its special imaging geometry,the highly squinted Terrain Observation by Progressive Scans(TOPS)SAR imaging mode is confronted with two main issues:severe range-azimuth coupling caused by high squint angles and azimuth spectrum aliasing caused by the steered azimuth beam.To solve these issues,a full aperture imaging algorithm based on the modified range migration algorithm(RMA)and spectral analysis(SPECAN)is proposed in this paper.Firstly,the two-dimensional(2-D)spectrum without aliasing is obtained by azimuth preprocessing.Then the modified RMA is used to complete range cell migration correction(RCMC)and range compression.Finally,the signal is focused in the Doppler domain by SPECAN and Deramping.Simulations and real data processing results validate the effectiveness of the proposed algorithm.