An Imaging Algorithm for Missile-borne SAR with Downward Movement Based on Azimuth Nonlinear Chirp Scaling

During the downward movement for missile-borne SAR, the assumption that echo signal invariance in azimuth is not accurate, which is caused by high vertical velocity and acceleration, making SAR imaging difficult to process. Due to this reason above, by using azimuth NonLinear Chirp Scaling (NLCS), an imaging algorithm for missile-borne SAR is proposed in this paper. After range cell migration correction and range compression in the 2-D frequency domain, via the Method of Series Reversion (MSR), azimuth variation of Doppler FM rates for echo signal can be compensated with the operation of azimuth nonlinear chirp scaling, which effectively improves focusing depth and focusing effect. Simulation results are provided to validate the effectiveness of the proposed algorithm.