A Space-Variant Phase Filtering Imaging Algorithm for Missile-Borne BiSAR With Arbitrary Configuration and Curved Track

The three-axis velocity and acceleration of platform not only reduce the accuracy of the traditional bistatic equivalent range model in the missile-borne bistatic synthetic aperture radar (BiSAR) with arbitrary configuration and curved track but also make the imaging algorithm based on the uniform linear track model inapplicable any more. In addition, due to the influence of space-variant motion errors introduced by double platform acceleration, the traditional 2-D subblock compensation method will cause discontinuities between image subblocks, and thus affect the subsequent image matching application. In view of these problems, this paper proposes a new BiSAR imaging algorithm, the space-variant phase filtering imaging algorithm (SVPFIA), which is based on the modified bistatic equivalent range model. SVPFIA constructs the combined compensating filter of space-variant phase error and geometric distortion and adopts inverse mapping interpolation. This makes it possible to achieve the local joint compensation of motion error, wavefront bending, and geometric distortion in the process of oblique conversion, and consequently yield the SAR ground image without distortion to facilitate the subsequent image matching process. Finally, the effectiveness of the proposed algorithm is examined through simulation experiments.