直升机载高分辨调频连续波旋转式SAR成像算法研究

本文提出一种新的基于调频连续波（Frequency Modulated Continuous Wave,FMCW）的直升机载旋转式合成孔径雷达（Rotating Synthetic Aperture Radar,ROSAR）成像模型,并给出了相应的成像算法.该方法首先利用等效相位中心原理,将收发分置天线系统的回波信号等效为“自发自收”单基系统.在此基础上,使用高阶逼近原理建立了ROSAR的回波信号模型,结合级数反演的思想推导出其精确的二维频谱表达式,分析了雷达天线连续运动的影响--产生多普勒频移,并给出其补偿方法.最后运用高效的Chirp-Z变换校正了距离单元徙动空变性,得到了聚焦良好的SAR图像.仿真结果验证了分析结论的正确性和算法的有效性.

High Resolution Imaging Algorithm for Helicopter-Borne Rotating Synthetic Aperture Radar Using Frequency Modulated Continue Waveform

A frequency modulated continue wave (FMCW) rotating synthetic aperture radar (ROSAR) imaging mode and corresponding imaging algorithm are presented.Firstly,the separated transmit antenna and receive antenna system are equalized to the case of system configuration with antenna both for transmitting and receiving signals according to the equivalent phase center principle.Based on this,by approximating the slant equation with the higher order model,one can obtain accurate two-dimensional frequency spectrum via the series reversion method.The Doppler frequency shift effect,induced by the platform's continuous motion while radar transmits and receives signals,is analyzed and the approximate compensation method is shown.Finally,efficient Chirp-Z transform (CZT) is applied to correct the range-variant range cell migration (RCM) and well-focused SAR image is obtained.Simulation results verify the correctness of the analysis and the validity of the proposed algorithm.