NLCS-SAR Imaging Algorithm with Range-walk Correction in Frequency Domain Based on Dive Model

The ordinary SAR imaging algorithms are inapplicable to missile-borne terminal guidance SAR due to its properties of high-speed, dive and high-squint. Based on the precise SAR echo signal in dive model, this paper proposes a new imaging algorithm of pre-correcting range-walk in frequency domain to translate high-squint imaging into equivalent low-squint even zero-squint one to simplify imaging processing. The pre-correction of range-walk will cause the variation of Doppler rate with azimuth time, which can be solved effectively by the azimuth Non-Linear Chirp Scaling (NLCS) processing. Therefore, after the azimuth NLCS processing, the azimuth compression in the same range gate can be carried out with the same Doppler parameters so that the azimuth Depth of Focus (DOF) can be improved. Simulation experiments validate the effectiveness of this algorithm.