A Highly Squinted-spotlight Imaging Algorithm Based on Spectral Analysis and Extended Non-linear Chirp Scaling

Due to the problem of azimuth spectral folding and large migration and strong range dependence on the second range compression for high-squinted spotlight. This paper proposes a method combining the advantages of SPECtral ANalysis (SPECAN) with Extended Non-linear Chirp Scaling (ENCS). First, after Range Cell Migration Correction (RCMC), azimuth spectral folding problem is removed by SPECAN. The variation of quadratic range cell migration correction is removed by chirp scaling. The chirp rates of scatterers in the same range gate are dependent on the azimuth position because of RCMC. So, the extended nonlinear chirp scaling is used to solve the problem of chirp rate dependent on azimuth position. Then focused scope of azimuth is extended. Simulation results verify that this method can get good quality image for high resolution in high squinted spotlight mode.