一种斜视滑动聚束SAR子孔径处理成像方法

子孔径法是解决滑动聚束SAR成像方位频谱混叠的有效方法，具有内存占用量低、灵活性高的特点。子孔径的划分不仅影响成像 质量，还会影响成像效率;但目前子孔径的划分大多采用经验值，理论上并没有给出明确分析。因此在斜视成像过程中，未合理划分的子孔径会导致拼接谱出现“空隙”现象。本文首先介绍了斜视滑动聚束SAR工作模型，分析了其方位多普勒历程，提出了斜视下基于方位频域Scaling的子孔径成像算法。根据相邻子孔径的二维频谱，研究了子孔径频谱拼接的准则，推导了确定子孔径长度与重叠率的解析式，给出了子孔径划分的流程，最后通过仿真 实验和实测数据处理验证了子孔径划分方法及斜视下成像算法的有效性。

Imaging Method for Sub-aperture Processing for Squinted Sliding Spotlight SAR

In the advantages of low memory requirement and high flexibility, sub-aperture method is effective in solving the problem of azimuth spectrum aliasing in sliding spotlight SAR imaging. Image quality and imaging efficiency are affected by sub-aperture partition. However, sub- aperture division usually relies on experience value, which cannot be given with a clear theory analysis at present. Therefore, spectrum gaps may appear in the squint imaging processing if sub-apertures are not properly divided. First, we introduce sliding spotlight SAR model and analyze its Doppler frequency history. A sub-aperture imaging algorithm for squinted sliding spotlight SAR is proposed based on azimuth frequency domain scaling. Then according to two-dimensional spectrum of the adjacent sub-apertures, we investigate the sub-aperture spectrum stitching principle and derive the two equations, thus determine sub-aperture length and overlap rate. Afterward the flow for partitioning sub-apertures is given. Finally, effectiveness of the sub-aperture partition method and squinted imaging algorithm is verified by simulation experiments and real data.