基于CZT的机载并行双站斜视SAR成像算法

建立了机载并行双站斜视合成孔径雷达(SAR)的几何模型,给出了雷达回波的数学表达式,推导了它的二维频谱并对其特点做了分析。在二维频域内,先用聚焦函数对观测场景中心的点目标做精确成像,然后用Chirp-Z变换(CZT)校正中心点两侧目标回波的距离徙动,再通过方位向逆傅里叶变换得到了雷达图像。该算法利用了CZT能够处理非线性调频信号的特点,简化了处理过程,提高了计算效率和成像精度。仿真实验验证了这种基于CZT的新算法在处理并行双站斜视SAR数据时的有效性。

Airborne Bistatic SAR Imaging Algorithm for Parallel Squint Mode Based on CZT

This article establishes the geometric model of an airborne bistatic synthetic aperture radar (SAR) for the parallel squint mode and presents the expression of the radar echoes, and then derives its two-dimensional spectrum with an analysis of its characteristics. In the two-dimensional frequency domain, the point targets in the center of the observed scene are precisely imaged by multiplying the focusing function, and then the Chirp-Z transforms (CZTs) are employed to correct the range cell migration of the target echoes in either side of the center points. Finally, radar images are generated by the inverse Fourier transform on the azimuth direction. Since the algorithm utilizes the property of the CZT to process the nonlinear modulation frequency signals, the processing procedure is simplified, and computational efficiency and imaging precision are greatly improved. The simulation tests validate this new algorithm based on the CZT to process the data of the airborne bistatic SAR for the parallel squint mode.