A generalized methodology based on higher-order conventional and non-standard FDTD concepts for the systematic development of enhanced dispersionlesswide-angle absorbing perfectly matched layers

A generalized theory of higher-order finite-difference time-domain (FDTD) s chemes for the construction of new dispersionless Berenger and Maxwellian u nsplit-field perfectly matched layers (PMLs), is presented in this paper. T he technique incorporates both conventional and non-standard approximating concepts. Superior accuracy and modelling attributes are further attained b y biasing the FDTD increments on generalizations of Padi formulae and deriv ative definitions. For the inevitably widened spatial stencils, we adopt th e compact operators procedure, whereas temporal integration is alternativel y performed via the four-stage Runge-Kutta integrator. In order to terminat e the PML outer boundaries and decrease the absorber's necessary thickness, various higher-order lossy absorbing boundary conditions (ABCs) are implem ented. Based on the previous theory, we finally introduce an enhanced refle ction-annihilating PML for wide-angle absorption. The novel unsplit-field P ML has a non-diagonal symmetric complex tensor anisotropy and by an appropr iate choice of its parameters together with new conductivity profiles, it c an successfully absorb waves of grazing incidence, thus allowing its imposi tion much closer to electrically large structures. Numerical results reveal that the proposed 2- and 3-D PMLs suppress dispersion and anisotropy error s, alleviate the near-grazing incidence effect and achieve significant savi ngs in the overall computational resources. Copyright (C) 2000 John Wiley & Sons, Ltd.