Multi-scale target detection for underground spaces with transient electromagnetics based on differential pulse scanning

Improvements in detecting underground spaces in urban areas require improvements to the radiation efficiency and resolving power of the artificial source. Due to the use of bipolar pulse and the low efficiency of the artificial source, the existing artificial sources have difficulty in accurately imaging complex urban underground spaces of varying depths and sizes, to complete the task of "transparent detection" of urban underground spaces to depths of two hundred meters. In this paper, a new type of transient electromagnetic radiation based on a high-performance artificial source and differential pulse is proposed. At the same time, multi-resolution theory and multi-scale information extraction technology are combined to further improve the resolution of the radiation field in imaging complex urban underground structures of varying sizes. With this new method, we are able to achieve our goal of transparent detection of 'two hundred meters' depths of urban underground space.