A NUMERICAL ABSORBING BOUNDARY-CONDITION FOR EDGE-BASED FINITE-ELEMENT ANALYSIS

The numerical absorbing boundary condition (NABC) approach is applied to the problem of deriving the local boundary conditions that can be employed in conjunction with the edge-based formulation of the finite-element method (FEM) to solve electromagnetic scattering and radiation problems. The key step in this approach is to derive linear relationships that link the values of the field along the boundary edges to those at the neighboring ones. These linear relationships are satisfied, to within a certain tolerance, by all of the outgoing wave components. They can thus be used in lieu of the FEM equations employing the usual absorbing boundary conditions for the boundary edges. The NABC approach not only provides a simple way to derive an accurate boundary condition for mesh truncation, but also preserves the banded structure of the FEM matrices. (C) 1994 John Wiley & Sons, Inc.