A Study On Fast Algorithms For3D Electromagnetic Scattering Problems For Composite Conducting And Dielectric Targets

With the development of science and technology, more and more engineering applications needelectromagnetic radiation and scattering analysis from3-D complex target. In this thesis, thePMCHW integral equation is implemented in analyzing dielectric objects and composite conducingand dielectric objects. By using H-Matrix method, the storage and computational complexities forsolving problems can be obviously decreased and it is possible to solve electrically-large objects.In this thesis, firstly, a fast algorithm (H-Matrix method) is introduced-Giving the method ofbuilding H-matrix and giving the storage and computational complexities. Secondly, by usingequivalence principle, the surface integral equations (PMCHW) for dielectric objects and compositeconducing and dielectric objects are built. The method of moments (MoM) analysis of the coatedconducting bodies, for an instance, is introduced. Then, several numerical examples show that thePMCHW integral equation for dielectric objects and composite conducing and dielectric objects iscorrect. As the number of unknown grows, the demanding computational resource increased rapidly.Then, the fast algorithm (H-Matrix) combined with CG iterative solution is employed to solveelectrically-large objects. The H-Matrix can be divided into near blocks and far blocks. The nearblocks are directly calculated with traditional MoM and far blocks are described by some low-rankmatrices. Low-rank matrices are got by degenerating kernel function. In this thesis, degeneratedkernel function is approximated with Lagrange polynomials. Finally, several numerical examplesshow that the H-Matrix method for dielectric objects and composite conducing and dielectricobjects is more efficient than traditional MoM.