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提出一种基于多频多单站体制的均匀地下介质中二维目标自聚焦成像算法.在Born近似下采用半空间谱域格林函数和目标的爆炸点模型推导出地下目标反演成像公式,借助快速Fourier变换实现地下目标的快速实时成像,避开了耗时较多的大型病态矩阵的正则化求解.针对地下介质电磁参数未知的情况,根据时间反转成像的原理和最小熵准则,进一步提出了目标的自聚焦算法.通过熵计算选取最优聚焦时间确定最优的聚焦图像,修正由于地下介质电磁参数估计偏差引起的成像的目标位置偏移及图像退化.文中用数值仿真的结果证明了在地下介质电磁参数未知情况下,提出的算法能在较短的计算时间内得到好的成像结果.
A two-dimensional target self-focusing algorithm based on multi-frequency and multi-station system is proposed in this paper. The Born approximation is used to derive the underground target inversion imaging formula by using the half-space Greenland function and the target explosion model. Fast Fourier Transform to achieve fast real-time imaging of underground targets, avoiding the more time-consuming large-scale illogical matrix regularization solution.According to the unknown electromagnetic parameters of underground media, according to the principle of time-reversed imaging and the minimum entropy criterion, further proposed The target self-focusing algorithm is selected by entropy calculation to select the optimal focusing time to determine the optimal focusing image and to correct the imaging target position deviation and image degradation caused by the deviation of the electromagnetic parameters of the underground media.In the paper, numerical simulation results show that Under the condition that the electromagnetic parameters of underground medium are unknown, the proposed algorithm can get good imaging results in a short computation time.