High-Resolution Bistatic Spotlight SAR Imagery With General Configuration and Accelerated Track

Due to the flexible configuration and maneuvering platform, bistatic synthetic aperture radar (BiSAR) plays an important role in modern remote sensing applications, but the nonideal track simultaneously introduces model mismatch and spatial-variant phase problems. This article proposes a subaperture (SA) parametric polar format algorithm (PFA) for high-resolution bistatic spotlight SAR (BSSAR) imaging. First, a bistatic parametric PFA (BPPFA) is proposed to focus on the generally configured BiSAR data. A high-precision range model in the bistatic range and ellipsoid parameter angle coordinate space is established to modify the PFA interpolation kernels. To further enhance the azimuth resolution, the PFA subimages are fused in the image domain based on the coordinate transformation between the unified Cartesian coordinates and local imaging polar coordinates. During the subimage fusion, in order to ensure the accurate projection and nonaliasing spectrum, we also consider the geometric deformation of the coarse PFA image and analyze the wavenumber support region along with the Nyquist sampling requirement. This novel SA method, which is theoretically more efficient than the fast back-projection algorithm (BPA), alleviates the limitation of full aperture resolution on PFA's depth of focus (DOF). Finally, our method is applied to the general BSSAR data, involving the level-flight airborne transmitter and the dive hypersonic vehicle-borne receiver, and the results of both points and distributed targets demonstrate its effectiveness and efficiency.