Wide-beam SAR autofocus based on blind resampling

Long synthetic aperture time and large instantaneous beam can turn airborne synthetic aperture radar (SAR) autofocus into a wide-beam autofocus problem; i.e., the motion error is both range- and azimuth-spatial variant. A typical two-step MoCo method cannot process wide-beam airborne SAR data. Moreover, traditional wide-beam SAR MoCo algorithms, such as sub-aperture topography and aperture-dependent (SATA), precise topography- and aperture-dependent (PTA), and frequency division (FD), are highly dependent on high-precision inertial navigation system/global positioning system (INS/GPS) data and belong to the sub-aperture method, which may result in serious grant-lobe or stitching problems in the image. Alternatively, this article proposes a full-aperture autofocus method for wide-beam SAR based on blind RS. The proposed method does not require INS/GPS data and avoids the problems of traditional sub-aperture methods, which can significantly improve the overall image quality. The measured data processing results of the wide-beam SAR verify the effectiveness of the proposed algorithm.