针对地球同步轨道圆迹SAR (GEOsynchronous Circular SAR, GEOCSAR)具有平台轨道高、斜椭圆形空间轨迹和椭球面成像区域等特点,需建立新的理论分析模型对其分辨特性进行评估。该文从建立观测目标与 SAR平台的空间几何关系出发,推导出目标点与场景中心对应的斜距差与圆迹方位角的函数关系,进而给出3维点扩展函数表达式,并得出分辨函数受sinc函数和贝塞尔函数共同影响的结论。然后重点分析了3维分辨特性随地理位置、信号带宽、圆迹半径和孔径大小的变化规律,最后通过信号仿真实验进一步对理论建模进行了验证。% GEOsynchronous Circular SAR (GEOCSAR), having a high orbit, operating in a slant ellipse, and imaging in spherical surface, should be newly modeled to assess the resolution performance. In this paper, starting from modeling geometry, a function of slant range difference and orientation angle is deduced. Then we can obtain the three dimensional point spread function and make a conclusion of resolution affected by both sinc function and bessel function of first kind. Lastly, resolution with the variation of location of target, bandwidth, radius of orbit, and integral time is analyzed detailedly. Finally raw signal simulations show the validity of theoretical model.
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