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 e mployed in conjunction with the edge-based formulation of the finite-e lement method (FEM) to solve electromagnetic scattering and radiation problems. The key step in this approach is to derive linear relationsh ips that link the values of the field along the boundary edges to thos e at the neighboring ones. These linear relationships are satisfied, t o 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 approa ch not only provides a simple way to derive an accurate boundary condi tion for mesh truncation, but also preserves the banded structure of t he FEM matrices. (C) 1994 John Wiley & Sons, Inc.