Hybrid finite-boundary element analysis of time harmonic electromagnetic fields.

摘要

The hybrid finite element-boundary element method (HEM) has been developed to provide an effective tool for the design and analysis of time harmonic electromagnetic field problems. Finite elements are used to represent the interior region which has sources and structures, and boundary elements are used to represent the boundary and can be used to evaluate the far-field. For implementation of the hybrid program, the Galerkin weighted residual method is employed using second-order triangular elements, and the boundary integral equation is evaluated using the point matching method.;Rectangular waveguide modes were investigated to verify that the proper mode was obtained. Also, the hybrid method was applied to the parallel-plate waveguide to analyze the near-field pattern as well as the far-field. It was found that the method was well adapted. The method was applied to Vlasov-type radiators and to various antenna systems with reflectors. The results of the method are in good agreement with the exact solution and with the geometrical theory of diffraction. Also an attempt was made to compare the results of 2-D numerical models with those of 3-D experimental work. The general trends of the far-field patterns are close to each other.;The absorbing boundary conditions (ABC) have been combined with the finite element method instead of the boundary integral equation in the HEM. The impact of the usage of the ABC is to reduce the computing memory and time. Another attempt has been made to reduce the computing time by using the nested dissection reordering algorithm (NDRA). Both the HEM and the ABC algorithm have been applied to solve various scattering problems for a scattered or total near-field pattern.;In addition, the FE formulation for the complex Laplace equation has been made to investigate the impact of convected charges on the electric field distribution of the insulation system of a power transformer. A new approach is introduced to analyze the oil-paper insulating system by superposing the three governing equations. This method will be a useful tool for analyzing and designing an insulating system.