SAR卫星多普勒频移偏航导引补偿效果分析

SAR卫星的多普勒中心频率与卫星和地面目标点间的相对运动有关，文章基于轨道动力学理论，把中心频率分解为两个部分，分别与卫星偏航姿态角相关和无关。对卫星施加偏航导引可以补偿前者，后者则作为噪声而存在。首先导出偏航导引的解析表达式，并简化为余弦函数形式使之适合实时计算；然后定义了补偿度的概念，理论上估计了施加偏航导引的补偿效果，同时在考虑地球为椭球体以及存在J2项摄动的条件下，通过对偏航导引简化公式补偿度的数值仿真，证明了补偿效果的理论估计方法在一定条件下的有效性，重点研究了补偿度与轨道偏心率和雷达侧视角的关系；最后进一步阐明轨道根数和雷达参数对补偿效果的影响，为SAR卫星的初步设计提供了理论支持。

The Effect Analysis of Yaw Steering's Compensation for Doppler Shift of SAR Satellite

The Doppler shift of SAR satellite is related to the relative motion between the satellite and the target. Based on the orbit mechanics theory the Doppler shift is splited into two parts: one has relation to the yaw angle that the be compensated and the other has nothing to do with it that can only be viewed as noise. First analytical solution for yaw steering is deduced and simplified to fit for real time computing. Then the concept of compensation effect is defined and the yaw steering's compensation effect is estimated by analysing the two parts, at the same time the results of simulation indicate that the method of theoretical estimation is conditionally effective. The relation between compensation effect and the orbit eccentricity or the elevation angle is also discussed. Last a conclusion about the effect of orbit elements and radar parameters on compensation is drawn to support the primary design of SAR satellite.