一种应用于地下腔体成像的新超宽带成像算法

摘要

To investigate the detection and recognition of underground cavity, a novel modified back projection algorithm based on the linear current radiation model of basic dipole is presented. The underground dielectric is analyzed, and the imaging model of underground cavity is built which the measured data is obtained through the half space finite difference time domain (FDTD). The computation formula of time delay compensation caused by the dielectric mutation is derived. The imaging result validates the accuracy of the modified back projection algorithm, and the effect of target structure to imaging is analyzed. The imaging of underground cavity is then studied. As well, the 3D imaging of cavity is provided to strength the ability of modified back projection algorithm.%为能有效地对地下空穴进行探测和识别，提出了一种基于基本振子线电流辐射模型的改进后向投影算法。分析了地下介质的物理模型，构建了地下腔体的成像模型及基于FDTD的全波电磁仿真模型，推导了半空间电磁波传播时延补偿的计算公式，验证了改进成像算法对地下腔体成像的有效性；分析了目标照射面结构对成像的影响，分别对照射面为凸面、平面、凹面三类目标进行了成像分析，得到能对凸面、平面照射面进行有效成像但不能对凹面照射面进行有效成像的结论，在岩、土体中孔穴的成像中得到了验证，并给出了多个孔穴存在时的三维像。