中文摘要：

与传统后向投影（Back—Projection，BP）算法相比，快速分解BP（FastFactorizedBP，FFBP）算法可以大幅度提高SAR成像的处理效率，具有较强的工程价值。该文在现有FFBP算法的基础上，提出了改进FFBP算法，进一步简化处理流程并提高运算效率。改进FFBP算法的主要特点：（1）成像平面选取在r—sinθ坐标系，代替现有FFBP算法的r—θ坐标系，从而直接避免了对投影视角的反正弦计算；（2）采用2维多项式拟合的方法对投影斜距和视角进行计算，代替现有FFBP算法的逐点计算或1维多项式拟合，从而大大减小了运算量。最后，利用X波段的SAR回波仿真数据对该文提出的改进FFBP算法进行验证。

英文摘要：

Due to the reduction in computational complexity, Fast Factorized Back-Projection （FFBP） has an obvious advantage over conventional BP in improving the processing efficiency of SAR. Based on the FFBP algorithm presented before, a novel FFBP algorithm which can reduce computational complexity further is proposed in this paper. The main characteristics of the novel FFBP are as follows： （1） with the imaging plane set on the r - sin θ coordinate system instead of polar coordinate system, there is no need to calculate the arcsines of the back-projected angle; （2） meanwhile, two-dimensional polynomial fitting method is introduced to obtain the values of back-projected slant range and angle without calculating point by point. Finally, the processing results of simulated X-band SAR data show the proposed algorithm is accurate and effective in reconstructing well focused images.