IMPLEMENTATION OF A SURFACE IMPEDANCE FORMALISM AT OBLIQUE-INCIDENCE IN FDTD METHOD

Modelling of interfaces between two media, using time-domain surface i mpedances, permits one to reduce the discretization volume in the fini te-difference time-domain (FDTD) technique. The method presented here is based on an exact formulation of surface impedances, starting from Fresnel reflection coefficients for oblique incidence of the incident wave. The concept, valid for homogeneous and frequency-independent med ia, is then introduced in an FDTD algorithm where it is converted into a surface-impedance boundary condition (SIBC) for vertical or horizon tal polarizations of locally plane waves. In this paper, two- and thre e-dimensional results are compared to those computed with classical FD TD or Fresnel reflection coefficients involving a Fourier transform.