Accurate Elimination Method of 3-D Acceleration for Highly Squinted TOPS SAR with Curved Trajectory

Abstract

When terrain observation by progressive scans synthetic aperture radar (TOPS SAR) system is mounted on a maneuvering platform, 3-D acceleration introduces envelope error and phase error into the complicated full aperture echo, which makes TOPS SAR image defocused. To solve this problem, a pre-processing is firstly performed to eliminate the spatially invariant envelope error of 3-D acceleration. Subsequently, a wavenumber-domain keystone transform is constructed to equalize the spatially variant linear Doppler phase. Finally, a wavenumber-domain resampling is adopted to equalize the higher-order Doppler phase, including spatial variance of Doppler rate and the azimuth-dependent phase error introduced by 3-D acceleration. Point target simulation shows that the proposed method can handle curved trajectory in highly squinted TOPS SAR geometry.