High Efficient Algorithms Of Method Of Moments For Scattering From Metallic And Homogeneous Bodies And Their Applications

Fast and accurate computation of electromagnetic scattering by metallic and complexhomogeneous objects is an important research topic in computational electromagnetics.Among various methods, the method of moments (MoM) is especially suitable for thispurpose due to its accuracy, efficiency and generality. Recently, with the growingrequirements in real life applications, accurate and efficient solutions of MoM havereceived wide attentions and become a key problem to overcome. We focus our aims in thisthesis on high efficient and accurate computational algorithms of MoM and intend to makea step forward in this direction. Our researches focus on three aspects: reducing the numberof unknowns with higher order basis functions; constructing efficient preconditioner toimprove convergence of iterative solutions; improving the accuracy of MoM by employingnew type of basis/test funcitons. Despite of the study on numerical performance of thesefast algorithms, we also apply the developed fast and accurate algorithms of MoM to solvea series of real challenge light scattering problems.We first introduce the background and the computational algorithm of MoM in detail.The accuracy and efficiency of different kinds of surface integeral equations for scatteringby homogeneous objects are investiguted both in theory and numerical experiments. Thishelps us have a better understanding on the numerical characteristics of different integeralequation forms.Then we apply higher order method of moments (HMoM) to solve homogeneousdielectric problems, the number of unknowns is reduced dramatically by using hierarchicalbasis functions defined on curve triangle, with good accuracy. Furthermore, an efficientpreconditioner is proposed to increase robustness and efficiency of iterative solutions ofdielectric problems formulated with the combined tangential formulation (CTF) based onhigher order hierarchical method of moments. Numerical experiments confirm that theproposed preconditioner can significantly improve convergence rates and reduce the CPUtime of dielectric problems formulated with CTF with the same accuracy.To improve the numerical accuracy of the Magnetic Field Integral Equation (MFIE),the Buffa-Christiansen (BC) function is applied as test function to improve accuracy of theMFIE dramatically by suppressing discretization error of the identity operators. When BCis used as test function, the original meshes are refined and CPU time for filling impendance matrix of the MoM will increase dramatically. Then the multilevel fastmultipole algorithm (MLFMA) is employed to accelerate iterative solution and make itapplicatable for larger problems. Numerical results show that by using BC function as thetest function, accuracy of the MFIE can be improved while maintaining its efficiency.Numerical results also show the effect of accuracy improvement by using BC as testfunction is affected greatly with curvilinear or plane triangular elements.In the end of this dissertation, we apply parallel MLFMA enhanced JMCFIE to solvelight scattering on large abitriry shaped particles. A series of numerical experiments areperformed to study the influence of size parameter, aspective ratio and different waveincidences. Physical explanations for some importran phenomenons are also given.