Nonrigorous symmetric second-order ABC applied to large-domain finite element modeling of electromagnetic scatterers

Abstract

Nonrigorous symmetric second-order absorbing boundary condition (ABC) is presented as a feasible local mesh truncation in the higher-order large-domain finite element method (FEM) for electromagnetic analysis of scatterers in the frequency domain. The ABC is implemented on large generalized curvilinear hexahedral finite elements without imposing normal field continuity and without introducing new variables. As the extension of our previous work, the method is comprehensively evaluated by analyzing several benchmark targets, i.e., a metallic sphere, a dielectric cube, and NASA almond. Numerical examples show that radar cross section (RCS) of analyzed scatterers can be accurately predicted when the divergence term is included in computations nonrigorously. An influence of specific terms in the second-order ABC, which absorb transverse electric (TE) and transverse magnetic (TM) spherical modes, is also investigated. Examples show significant improvements in accuracy of the nonrigorous second-order ABC over the first-order ABC.