The generalized TLM-based FDTD modeling of frequency-dependent and anisotropic media

A generalization of the previously proposed transmission-line matrix (TLM)-based finite-difference time-domain (FDTD) method is presented for modeling frequency-dependent and anisotropic media. The generalized scheme incorporates electric- and magnetic-flux densities in addition to variable mesh sizes. Since it is in an FD form, modeling techniques developed for the conventional FDTD can be easily adapted into the proposed TLM-based technique. In this paper, a modified z-transform technique for frequency-dependent media is implemented, and a two-dimensional (2-D) full-wave technique for guided-wave structures is developed. In all the FDTD computations, no conversions between the field quantities and TLM circuit parameters such as open- and short-circuited stubs are required.