A NUMERICAL ABSORBING BOUNDARY-CONDITION FOR QUASI-TEM ANALYSIS OF MICROWAVE TRANSMISSION-LINES USING THE FINITE-ELEMENT METHOD

This article presents a new numerical absorbing boundary condition use ful for quasi-TEM analysis of open-type microwave transmission lines e mploying the finite-element method (FEM). The standard FEM equations a re used for the inner nodes of the mesh, and mesh truncation is achiev ed by imposing linear relationships for the nodes on the outer boundar y and their neighbors, which are derived from the appropriate Green's functions. This approach greatly reduces the mesh size, while preservi ng the sparsity of the FEM equations. Higher-order approximations of t he absorbing boundary condition are derived through the use of higher- order-finite elements. (C) 1995 John Wiley & Sons, Inc.