一种适用于大场景圆迹环扫SAR的改进CS成像算法

在宽测绘带圆迹环扫合成孔径雷达(CSSAR)中，目标斜距表示形式复杂，测绘带内距离徙动(RCM)变化剧烈均给成像处理引入难点。针对上述问题，根据圆迹环扫SAR平台的运动特性，使用高阶逼近的方法建立圆弧曲线模型下的回波信号斜距方程，并以导出的二维频谱高阶近似解析表达式为基础，考虑大场景下的距离徙动空变问题，对空变的斜距历程进行详细的分析，并提出了一种适用于大场景圆迹环扫SAR的改进线性调频变标(CS)成像算法。仿真结果说明，曲线模型的斜距方程精度较高，该算法能够精确校正空变的距离徙动，对较大场景取得了较好的成像效果。

An Improved CS Imaging Algorithm for Large Scene Circular Scanning SAR

For wide swath circular scanning synthetic aperture radar (CSSAR), the complex slant range history and large variant range cell migration (RCM) makes it difficult to implement imaging. To deal with the problem, the echo signal slant range equation of curve trajectory model is established by using high order approximation according to the characters of the CSSAR movements. The range-variant range history is analyzed in details and an improved Chirp Scaling (CS) imaging algorithm for large scene CSSAR is proposed based on the derived high order approximated two-dimensional spectrum. Simulation results demonstrate that the range equation under curve trajectory model is more precise and the algorithm can deal with the problem of the range-variant RCM perfectly and realize the large scene imaging successfully.