Modified Full-aperture Omega-k Algorithm for Circular-track Ringmap Mode SAR

Circular-track ringmap SAR (CTR-SAR) has the great advantages of wide imaging coverage and no blind imaging area compared to linear-track SAR. Nevertheless, at present, the related imaging algorithms are all based on sub-aperture, and their computational efficiency and imaging accuracy cannot be achieved well at the same time. This paper analyzed the range-angle two-dimensional spectrum of CTR-SAR in detail. Based on the spectrum, a modified full-aperture omega-k imaging algorithm is proposed. The full-aperture imaging algorithm can be divided into three steps: coarse focusing to unified process radar data, fine focusing to eliminate the residual range-variant phase error, and coordinate transformation to get the imaging map. Finally, numerical simulation experiments verified the effectiveness of the proposed algorithm.