求解回波信号的二维频谱是双基地合成孔径雷达(Bi-SAR)系统成像的关键问题,传统方法主要有Loffied双基公式法(LBF)和扩展Loffied双基公式法(扩展LBF)。而对于地球同步轨道星机双基地合成孔径雷达(GEO星机双基地SAR)来说,由于收发平台具有明显的异构性,采用传统方法求解回波信号二维频谱会产生较大的误差。文中针对GEO星机双基地SAR系统的结构特点,提出采用多普勒贡献比加权(DDW)的方法来求解回波信号的二维频谱,并通过仿真分析比较了LBF、扩展LBF、DDW三种方法求解回波信号二维频谱的相位误差;然后,选取GEO星机双基地SAR场景下的点目标,利用求解得到的二维频谱进行仿真成像;最后,比较了成像效果,说明采用DDW方法求解该模式下回波信号二维频谱的优越性。

For bistatic synthetic aperture radar ( SAR) system, the key of imaging is to derive the echo signal忆s two-dimensional spectrum, and the main methods are Loffied’s bistatic formula (LBF) and extended Loffied’s bistatic formula (ELBF). While in geosynchronous spaceborne-airborne bistatic SAR system, because of the sending and receiving platform’s isomerism, using the traditional methods to derive the echo signal’s two-dimensional spectrum will cause big error. In this paper,according to the structure characteristics of GEO spaceborne-airborne bistatic SAR system, the method of using the Doppler distribution weighed (DDW) to estimate the echo signal忆s two-dimensional spectrum is proposed,and the phase error of LBF、ELBF and DDW is compared by simulation. Finally the advantage of DDW to derive the two-dimensional spectrum is indicated by simulation of point targets imaging.

TN911.7