Efficient analysis of EM scattering from 3D complex conducting objects buried under ground

Electromagnetic scattering by three-dimensional complex perfect electrically conducting (PEC) objects buried under ground is investigated in this paper. The air-soil composite is approximated by a half-space model, where the half-space Green's function is adopted in the formulation of the electric field integral equation (EFIE). The simulation efficiency is improved from the following two aspects: a novel half-space Calderón preconditioner is developed to improve the spectrum of the EFIE operator, and thus the convergence rate of the matrix system; a half-space multilevel fast multitpole algorithm (MLFMA) based on real-image approximation is further adopted to accelerate each matrix-vector product and reduce the memory requirement. Numerical results are presented to demonstrate the effectiveness of this method for the applications of underground detection.