FDTD surface impedance models for electrically thick dispersive material coatings

Abstract

[1] A new accurate finite-difference time-domain model of dielectric and conductive layers on metal surfaces is developed. The model is based on higher-order surface impedance boundary conditions (SIBC). Several improvements to the existing numerical SIBC models are presented. The most important features of the proposed model are the inclusion of the tangential variations of the fields into the model and a considerably more accurate approximation of the impedance function than in the earlier works. In addition to the usual dielectric and conductive layers, the model can also handle layers of Lorentz, Debye, or Drude media. It is shown that the range of applicability of the proposed SIBC model is greatly increased as compared with the earlier models. Verification of the model is performed with one-and two-dimensional simulations. The results are compared with the exact results in both time and frequency domains. Also, a comparison with an earlier model is provided.

A Robust Method to Accurately Treat Arbitrarily Curved 3-D Thin Conductive Sheets in FDTD

“…Introducing the common normalized factor using and with the free space values and removes one degree of freedom. This yields in the limit of an infinitesimally refined grid (13) which leads to the following formula for the 1-D coefficient and the corresponding update coefficients for the sheet edge (14) (15) (16) This solution fits nicely into the established material coefficient schemes: For and , i.e., for PEC, it follows that . For and , i.e., free space, it follows that .…”

“…Multiple approaches to treat TC sheets [2]- [9], an overview can be found in [10] and thin layers in general [11]- [16] with the FDTD method have been reported. However, most suffer from the fact that they show results for flat, grid-aligned sheets only.…”

Implementation of Collocated Surface Impedance Boundary Conditions in FDTD

“…with inverse Laplace transform in the time domain as (11) where , and are the modified Bessel functions of the first kind of order zero and one, is the Heaviside unit step function, and is the Dirac delta function. The electric field is a convolution (12) and the discrete sum is…”