MIMO雷达近场成像校准与互耦合补偿方法

毫米波频段的合成孔径雷达（Synthetic Aperture Radar, SAR）因拥有良好的方位向分辨率而受到广泛关注，同时在发射端和接收端采用多根天线多输入多输出（Multiple?Input Multiple?Output, MIMO）的方式可以极大提高信道容量。然而MIMO?SAR图像重建计算较为复杂，且多个通道间幅相不一致和相互耦合容易导致图像出现伪影，严重影响成图质量。基于此，本文对引入非均匀快速傅里叶变换（Nonuniform Fast Fourier Transform, NUFFT）简化的距离迁移算法（Range Migration Algorithm, RMA）成像算法进行了研究；在分析扫描架运动抖动对相位影响的基础上，探究了通过照射金属反射面的MIMO阵列校准方法，实现了192个通道的同时校准；并搭建了毫米波SAR系统实验平台，对伪影消除、成像分辨率等开展了验证实验。实验结果实现了图像重构，成像分辨率达到了2 mm，完成200 mm×200 mm孔径扫描时间缩短至120 s。

Method of Calibration and Mutual Coupling Compensation for MIMO Radar Near Field Imaging

Millimeter wave synthetic aperture radar (SAR) has attracted widespread attention due to its good azimuth resolution, meanwhile, multiple?input multiple?output (MIMO) with multiple antennas at the transmitting end and receiving end can greatly improve the channel capacity. However, the calculation of MIMO?SAR image reconstruction is relatively complex, and the inconsistency of amplitude and phase between multiple channels and mutual coupling can easily lead to artifacts in the image, which seriously affects the image quality. Based on this, this paper studies the range migration algorithm (RMA) imaging algorithm simplified by nonuniform fast Fourier transform (NUFFT), explores the calibration method of the MIMO array by illuminating the metal reflective surface under the analysis of the influence of the motion jitter of the scanning gantry on the phase, and realizes simultaneous calibration of 192 channels. A millimeter?wave SAR system experiment platform was built, and experiments on artifact elimination and imaging resolution verification were carried out. The experimental results have achieved image reconstruction, the imaging resolution has reached 2 mm, and the scanning time with an aperture of 200 mm×200 mm has been shortened to 120 s.