地球同步轨道SAR曲线轨迹二维空间分辨率分析

Analysis of the two-dimensional spatial resolution for the curved trajectory of GEO SAR

针对地球同步轨道合成孔径雷达(GEO SAR)中,卫星轨道是曲线轨迹,且由于地球自转等因素的影响,卫星相对于点目标的运动轨迹没有显式表达式,且航迹速度在不同的卫星轨道位置差异很大的问题,提出了一种基于相位梯度分析的高轨SAR二维空间分辨率计算方法.文中提出了一种猜想,并采用介值定理证明:在合成孔径时间内,存在1个等效航迹速度,使得理论方位向分辨率位于1个范围之内,并计算得到了该方位向分辨率范围.最后,后向投影算法仿真实验验证了该方法的有效性.

In geosynchronous earth orbit synthetic aperture radar（GEO SAR）, because of such factors as the curve track of the satellite, the influence of earth rotation and so on, there is no explicit expression for the moving track of the satellite with respect to the target, and the track velocity varies greatly on different obit positions of the satellite, so the method of calculating resolution for uniform line motion in airborne and LEO SAR is not suitable for GEO SAR. Aiming at the mentioned problems, this paper proposes a method of calculating the two-dimensional spatial resolution based on phase gradient analysis in GEO SAR. In this paper, a conjecture is presented and proved by introducing the intermediate value theorem. There exists an equal track velocity, which can ensure the theoretical azimuth resolution within a range, and that azimuth resolution range is calculated. Finally, the Back projection （BP） algorithm simulation experiments validate the proposed method.