The efficient implementation of the surface impedance boundary condition in general curvilinear coordinates

This paper discusses the efficient incorporation of skin-effect losses into the nonorthogonal finite-difference time-domain technique. A survey of pre vious work is presented and it is shown that the exponential approximations used by previous methods mag lead to considerable error when good conducto rs are modeled using a fine time discretization. Subsequently, an improved exponential approximation is given and applied to various curved conducting waveguide surfaces using the nonorthogonal finite-difference time-domain t echnique.