中文说明：
本程序是自己刚刚接触SAR时编写的时域星载SAR点目标回波仿真，包含了卫星轨道模型、计算星目斜距时用到的各种坐标系转换、SAR回波计算模型以及简单的SAR成像模型，希望对初学者有所帮助。
相应的参考资料可查找《卫星轨道姿态动力学与控制》及《魏钟铨_合成孔径雷达卫星》
English Description：
1.This program is a time-domain spaceborne SAR point target echo simulation written when I just contact with SAR, including satellite orbit model, various coordinate system transformation used in calculating star target slant range, SAR echo calculation model and simple SAR imaging model, hoping to help beginners. 2.The corresponding reference materials can be found in "satellite orbit and attitude dynamics and control" and "Wei Zhongquan"_ Synthetic aperture radar satellite