基于非均匀 FFT 的超宽带合成孔径雷达高效成像算法

摘要

In the ultra-wideband synthetic aperture radar(UWB-SAR)imaging algorithms the back-projeetion al-gorithm(BPA)and the extended Omega-K algorithm(EOKA)have high imaging accuracy.But the complex interpola-tion operation in the imaging process brings about heavy computational load.The nonlinear chirp scaling algorithm (NCSA)does not need a complex interpolation process and has a higher imaging efficiency.Due to the approximation in the series expansion process,SAR images contain certain range and azimuth coupling sidelobe.This paper presents a new UWB-SAR imaging algorithm.The proposed algorithm does non-uniform FFT on the range-time domain data af-ter range compression to cancel the range and azimuth coupling.The images delete the range and azimuth coupling side-lobe and have high quality.As the data number increases the proposed algorithm imaging efficiency is closer to NCSA imaging efficiency.Simulation results verify the correctness of the proposed algorithm.%超宽带合成孔径雷达（ultra-wideband synthetic aperture radar，UWB-SAR）成像算法中后向投影算法（back-projection algorithm，BPA）和可扩展的 Omega-K 算法成像精度很高，但成像处理中的复数插值操作带来了较大的运算负担。非线性调频变标算法（nonlinear chirp scaling algorithm，NCSA）不存在复数插值处理，成像效率较高，由于级数展开处理存在近似，SAR 图像存在一定的距离方位耦合副瓣。提出了一种新的 UWB-SAR 成像算法，通过对 SAR 距离脉压后的距离时域数据进行非均匀傅里叶变换，去除距离方位的耦合。图像消除了距离方位耦合副瓣，具有较好的质量。随着成像点数的增多，本文算法成像效率接近 NCSA 成像效率。仿真结果验证了该算法的正确性。