Maneuvering platform high-squint SAR imaging method based on perturbation KT and subregion phase filtering

Abstract

The imaging parameters of high-squint synthetic aperture radar (SAR) mounted on maneuvering platforms have obvious spatial variability, which cannot be effectively solved by traditional SAR imaging algorithms and limits the focus depth. To extend the focus depth of maneuvering SAR, an imaging method is proposed based on perturbation keystone transform (KT) and subregion phase filtering (SRPF). In the process of range cell migration correction, the azimuth-dependent range curvature is corrected by introducing the perturbation factor in two-dimensional (2-D) frequency domain, and then the linear range cell migration is corrected by conducting the azimuth KT. In the process of azimuth compression, after removing the negative influence generated by the 2-D frequency-domain perturbation, the precise azimuth time-domain phase is reconstructed. And then, the method of SRPF is proposed to extend the azimuth focus depth. This method divides the range cell into several subregions and carries out the phase filtering and deramp process in each subregion. Theoretical analysis and simulation results show that the proposed method has high efficiency and can effectively expand the focus depth of high-squint SAR mounted on maneuvering platforms.