一般构型机载双站SAR回波信号特性分析

一般构型机载双站合成孔径雷达(SAR)的成像结构与系统参数使其回波信号具有新的特性,文中从残余距离徙动、多普勒参数、回波频谱三个方面对信号特性进行分析。研究结果表明,残余距离走动与残余距离弯曲具有方位向非对称性,宽场景成像中需按照残余距离徙动与二阶相位误差对观测场景进行成像区分块;多普勒质心具有二维扩散性,多普勒调频率与多普勒带宽具有二维扩展性;在距离频域-方位时域校正距离走动可削弱因双站斜视带来的回波信号距离-方位向二维强耦合,推导了距离走动校正后的回波频谱公式。仿真验证了一般构型机载双站SAR的信号特性与距离走动校正方法的有效性。

Analysis of Echo Signal Properties of General Case Airborne Bistatic SAR

The echo signal of general case airborne bistatic SAR has new properties because of its imaging geometry and systemic parameters. Three aspects of signal properties as residual range migration, Doppler parameters, spectrum of echo signal are analyzed in this paper. The research results are as follows: residual range walk and residual range curvature are asymmetry in azimuth, and imaging region blocking should be performed in wide scene imaging according to the residual range migration and quadratic phase error (QPE). Doppler centroid is two-dimensional divergent, while Doppler chirp rate and Doppler wideband are twodimensional expansionary. Linear range walk correction (LRWC) is performed in range frequency-azimuth time domain to mitigate the strong cross coupling of echo signal that brought by the squint mode of bistatic SAR. The point target spectrum after LRWC is derived. Simulations validate the properties of echo signal and the method of LRWC.