[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - MLFMA-ACA Based Method for Efficient Calculation of Scattering from Underground Targets

摘要： Electromagnetic (EM) non-destructive evaluation (NDE) of underground targets is of great significance for the safety of urban construction. Succesful detection of underground targets during construction depends on the accurate and efficient simulation of wave propagation. Among the most popular numerical methods in electromagnetics, surface integral equation (SIE) based method of moments (MoM) is used to simulate the scattering from underground targets in this paper. While MoM has high computational complexity O(N^2) and memory cost O(N^2) if iterative solver is applied, where N is the number of unknowns. As one of the most efficient fast algorithms, multi-level fast multi-pole algorithm (MLFMA) is used to reduce the computational complexity and memory cost. However, MLFMA is more difficult to calculate in this case because of the coupling action between rough surface and target has its limitations. So, adaptive cross approximation (ACA) is used to solve this problem. In this paper, a hybrid method combining MLFMA and ACA (MLFMA-ACA) is proposed to compute the scattering from underground targets. While MLFMA is used to compress the coupling matrix between rough surface and target, ACA is added to compress the coupling matrix between different media targets. The combination between them can build a more efficient method to compute scattering from underground targets.