Design of Planar Absorbing Layers for Domain Truncation in FEM Applications

ABSTRACT

A metal-backed layer of absorbing material offers a number of advantages for truncating the computational domain in a finite element simulation. In this paper we present design curves for the optimal selection of the parameters of the layer to achieve a specified reflection coefficient. The curves are based on one-dimensional finite element simulations of the absorbers, and the optimization is therefore a function of the sampling rate. Three types of material are considered, including the recently introduced perfectly matched uniaxial material, either homogeneous or with a quadratic material profile. Two three-dimensional applications are also presented and used to examine the validity of the design curves.