An Improved RD Imaging Method for SAR on Geosynchronous Orbit

Synthetic aperture radar on geosynchronous earth orbit (GEOSAR) has the significant potential advantages over the Low Earth Orbit SAR, such as the short revisit period and the large coverage area. However, the key problems in GEOSAR imaging process are curve trajectory, path delay and atmospheric delay, all of that will result in the defocusing with the classical imaging algorithm. Hence, we firstly deduce the expression of the slant range with the curve traj ectory for the elliptic orbital movement of GEOSAR, and further modify this equation due to the issues of the path delay and atmospheric delay. And then, an improved RD algorithm based on the above slant range model is proposed in this paper. Finally, the imaging simulations for the point targets are implemented nearby the minimum velocity and the maximum velocity of GEOSAR. And the imaging results further demonstrate the effects of the curve traj ectory and total delay, and show the correctness and effectiveness of the new imaging technique.