弹载合成孔径雷达大斜视子孔径频域相位滤波成像算法

摘要

The missile-borne Synthetic Aperture Radar (SAR) usually adopts the highly squint mode and subaperture to satisfy maneuvering and the real-time processing, but the signal of highly squint SAR is coupled greatly between the azimuth and range. This issue can be solved by removing the range walk in the time domain, but costs the limitation of focus depth. Due to the depth of focus and the characteristics of subaperture, a new subaperture imaging algorithm—Frequency Phase Filtering Algorithm (FPFA) is proposed in this paper. Without any approximation of the slant range, the range walk can be done in the time domain and the range curvature removed in the frequency domain. Then, a new high-order equation of phase filtering factor is introduced into the frequency domain in order to correct the azimuth-dependence. Finally, the signal is focused in the Doppler domain by SPECtral ANalysis (SPECAN) technique. Both the simulation results and real data processing validate the effectiveness of the proposed method.%弹载合成孔径雷达(SAR)为满足机动性和实时性，常采用大斜视子孔径成像处理；而大斜视SAR成像存在严重的距离方位耦合，时域校正距离走动解决这一问题会带来方位聚焦深度问题。针对方位聚焦深度问题以及子孔径特性，该文提出一种新的子孔径成像算法—频域相位滤波算法(FPFA)，该算法在无近似瞬时斜距模型下，采用时域校正距离走动，频域校正弯曲，在方位频域引入相位滤波因子校正多普勒调频率和方位向高次项的空变性，并结合谱分析(SPECAN)技术实现方位聚焦。仿真和实测数据处理验证了该算法的有效性。