The third chapter is experiment analyses of multi - aperture transient electromagnetic method , it analyzes multi - aperture transient method in theory and discusses radiation direction characteristic of first field by means phased array theory and integrating result of experiment contrast . according to kinematics character it also brings forward similar interference concept and analyzes reason of similar interference phenomenon , it gained footing between similar interference item and depth on the base of it and experiment formula 借助于相控阵原理的思想，结合模拟实验观测值对比结果，对多孔径tem方法进行模型分析，详细讨论了多孔径一次场的辐射方向特性，利用光波的运动学特征提出类相干的概念，分析了多孔径tem辐射源存在类相干现象，推导出类相干实验公式，并得出类相干项与多孔径框边长以及埋深的关系表达式和。
