ELECTROMAGNETIC SCATTERING OF LARGE STRUCTURES IN LAYERED EARTHS USING INTEGRAL-EQUATIONS

An electromagnetic scattering algorithm for large conductivity structu res in stratified media has been developed and is based on the method of system iteration and spatial symmetry reduction using volume electr ic integral equations. The method of system iteration divides a struct ure into many substructures and solves the resulting matrix equation u sing a block iterative method. The block submatrices usually need to b e stored on disk in order to save computer core memory. However, this requires a large disk for large structures. If the body is discretized into equal-size cells it is possible to use the spatial symmetry rela tions of the Green's functions to regenerate the scattering impedance matrix in each iteration, thus avoiding expensive disk storage. Numeri cal tests show that the system iteration converges much faster than th e conventional point-wise Gauss-Seidel iterative method. The numbers o f cells do not significantly affect the rate of convergency. Thus the algorithm effectively reduces the solution of the scattering problem t o an order of O(N-2), instead of O(N-3), as with direct solvers.