为了将机载SAR超高分辨率（01 m）条件下的超大带宽信号的实现和成像信号的处理进行有效结合，首先深入分析了基于PFA的2维重叠子孔径处理算法（PFOSA），并对算法中采用的不合理近似进行了改进；然后将PFOSA应用于调频步进信号的 SAR成像处理，在此基础上，提出了一种基于调频步进信号的2维子孔径处理算法。该算法不仅能够将调频步进信号处理与距离子孔径处理相结合，使之无需常规的脉冲合成过程，而且还能够利用子孔径处理获得的目标粗分辨位置信息来有效补偿脉冲簇内由载机运动引起的空变相位误差，从而克服了常规脉冲合成方法无法补偿空变相位误差的缺点。仿真数据处理结果表明，该算法是有效的。

In this work, a 2D overlapped sub-aperture polar format algorithm (PFA) based on stepped-chirp signal is proposed. In synthetic aperture radar (SAR) with stepped-chirp signals, instead of using traditional pulse synthesis to conduct preprocess, the presented method integrates the pulse synthesis process into the range sub-aperture processing. Meanwhile, due to the multi-resolution characteristics of sub-aperture processing, this algorithm is able to compensate the space-variant phase error caused by the radar motion during the period of a pulse cluster. Finally, experiments carried out on simulated and measured data confirm the validity of the algorithm.