一种大斜视双基地合成孔径雷达的频率变标成像算法

摘要

Since the two-dimensional spectrum of a point target cannot be obtained precisely by bistatic synthetic aperture radar (SAR), and the imaging results are not satisfied for high-squint-angle in front target observing, a new frequency scaling (FS) algorithm is proposed for high-squint-angle SAR based on the exact analytical bistatic spectrum. The method first transforms the echo into the two-dimensional frequency domain, and then chooses a frequency scaling function that is obtained based on an exact analytical spectrum to equalize the range migration of all points. Then, elimination of the residual video phase caused by the dechirp operation and inverse frequency scaling is performed to correct the second-order phase error. After range migration correction, the range-dependent second range compression term is eliminated using the nonlinear frequency scaling operation. The image is finally obtained by range and azimuth compression. Simulation results and comparisons with the normal FS algorithm show that ideal imaging can still be achieved even if the bistatic SAR system works at the equivalent high-squint-angle mode, and the main lobe and sidelobes of the impulse response of the point target can be well-resolved.%针对具备更多目标散射信息的双基合成孔径雷达的目标二维频谱难以精确获得,以及为观察前方目标采用的大斜视构型导致的成像效果不佳的问题,提出一种基于严格解析双基频谱的大斜视频率变标(FS)成像算法.首先将回波信号变换到二维频率域,利用由严格解析双基频谱推导出的频率变标函数校正距离弯曲差,然后进行剩余视频相位校正完成包络去斜,接着进行逆频率变标操作消除二次相位误差,经过距离徙动校正后,再进行非线性变标操作消除由大斜视导致的随距离变化的二次距离压缩项,最后经过距离压缩和方位压缩完成整个成像过程.仿真实验表明,与常规FS算法相比,在双基地大斜视的情况下,该算法成像效果良好,点目标冲激响应的主副瓣可清晰分辨.