A Range Perturbation Approach for Correcting Spatially Variant Range Envelope in Diving Highly Squinted SAR With Nonlinear Trajectory

The image processing for diving highly squinted synthetic aperture radar (SAR) mounted on a maneuvering platform with nonlinear trajectory is challenging due to the spatial variance in the range envelope along azimuth, which is caused by the inherent range dependence of squint angle, platform acceleration, and the range cell migration (RCM). In order to deal with the spatial variance that leads to defocusing in SAR imaging, a range perturbation approach is proposed in the frequency domain to mitigate the azimuth-dependent RCM curvatures, so that the RCM can be uniformly compensated for in the 2-D frequency domain. Moreover, this approach is totally interpolation free, and thus the computation load is reduced dramatically. The effectiveness of the proposed approach is confirmed and demonstrated via simulations.