中文摘要：

一站固定式双基地低频UWBSAR具有方位移变的距离徙动和较长的合成孔径，这导致其距离方位耦合变得非常复杂，从而限制了频域算法的应用．为此，本文提出一种基于椭圆极坐标的一站固定式双基地低频UWBSARFFBP算法．基于一站固定式双基地SAR的成像几何，分别推导了直角坐标与椭圆极坐标下后向投影算法的解析表达式，并讨论了双基地FFBP算法中采用椭圆极坐标的优势．然后分别从频带和斜距误差角度推导了子图像的采样间隔．最后讨论了该算法的实现过程和计算量．仿真结果证明了所提方法的有效性．

英文摘要：

One-stationary bistatic low frequency ultra wide band synthetic aperture radar （UWB SAR） has the azimuth-vari- ant range cell migration and longer synthetic aperture, which greatly complicates the range-azimuth coupling and limits the applica- tion of frequency-domain algorithms. In this paper, a fast factorized back projection （FFBP） algorithm based on elliptical polar coor- dinate is presented to focus the one - stationary bistatic low frequency LrWB SAR data. Based on the imaging geometry, the analyti- cal expressions of the back projection （BP） algorithm in Cartesian coordinate and elliptical polar coordinate systems are derived,re- spectively. The advantage of implementing the bistatic FFBP algorithm in elliptical polar coordinate is analyzed. Then, the sampling requirements for subimages are deduced from the bandwidth and bistatic range error angles, respectively. Finally, the implementation and the computational burden of this algorithm are discussed. Simulation results prove the validity of the proposed approach.