A NOVEL AUTOFOCUSING TECHNIQUE BASED ON PGA FOR THE POLARIMETRIC SAR APPLICATION

The phase gradient autofocus (PGA) algorithm is widely used for synthetic aperture radar (SAR) autofocusing. In practice, polarizations of electromagnetic waves result in phase error estimates with different precisions obtained by PGA, yielding distinctly focused images for different polarization channels after compensating the phase errors. In this paper, a new autofocusing technique for the polarimetric application is proposed. The algorithm employs the redundancy of phase error information among different polarization channels. The phase error estimate obtained by different polarization channels which optimizes the image quality with the highest image contrast is treated as the final estimation result. In comparison with the standard PGA, the performance of the proposed approach is demonstrated using real data from airborne SAR.