An Autofocus Scheme of Bistatic SAR Considering Cross-Cell Residual Range Migration

Benefiting from the capability of forward-looking imaging, ability of receiver radio silence, and resistance of jamming, bistatic synthetic aperture radar (SAR) has extensive potential applications. However, due to its independent dual platform movement, motion error of bistatic SAR is usually more complicated than monostatic SAR and could easily exceed range resolution cell, which will result in both azimuth and range defocusing if not properly compensated. In this letter, an autofocus scheme for bistatic SAR considering cross-cell residual range migration is proposed. In this scheme, cross-cell residual range migration is first compensated by estimating bistatic range error through time–frequency analysis. Meanwhile, azimuth phase error is coarsely compensated by using bistatic range error estimation result. Second, maximum image sharpness autofocus method is cascaded to further compensate for azimuth residual phase error and enhance the quality of bistatic SAR image. The effectiveness of proposed scheme is verified by simulation and experiment results.