Research On Scattering From 3-D Targets In The Subsurface

The main work of the dissertation focus on scattering from 3-D targets in the subsurface. Two key problems, fast-calculating Sommerfeld Integrals (SIs) and dealing with singular points, in calculating the EM scattering from 3-D targets in the subsurface using the Method of Moment (MoM) are studied. And an accurate and efficient implementation approach of MoM is developed to compute scattering from 3-D targets in the subsurface, which is based on the Mixed Potential Integral Equation (MPIE) in layered media and the RWG basis function.In the research of fast-calculating SIs, Generalized Pencil of Function (GPOF) method and two-level GPOF method are introduced first and then, a given SI in analyzing EM scattering of underground targets is simulated by GPOF method and two-level GPOF method and some suggestions are made about main parameters used in the methods. Numerical results show that two-level GPOF method is better than one-level GPOF method in parameter unification and project realization for this type of integral.In the research of dealing with singular points, two methods are first described, and then the applicability and validity of the two methods are carefully investigated. Numerical experiments are performed at last.In the research of calculating EM scattering from 3-D targets in the subsurface using MoM, an accurate and efficient implementation approach of MoM is developed to compute scattering from 3-D targets in the subsurface, which is based on the MPIE in layered media and the RWG basis function. The implementation skill and computing performance of the proposed approach are studied in detail. In particular, how to efficientlycalculate various different Sommerfeld Integrals (Sis) is numerically investigated with the discrete complex images technique. The computed results of subsurface flat are in agreement with the published data, which shows.the reliability, efficiency and accuracy of the developed approach. Furthermore, the EM scattering of other shaped targets is computed at different size, buried depth, and subsurface medium.