Low Dispersive Compact ID-FDTD Algorithm for Electrically Large Waveguides

A novel compact finite difference time domain (FDTD) scheme is proposed to remedy the anisotropic dispersion characteristic and inaccurate transverse cutoff frequency observed in conventional compact FDTD schemes. The proposed scheme is formulated based on the two-dimensional (2D) isotropic-dispersion finite difference (ID-FD) equation (I. Koh, et al, “Novel explicit 2-D FDTD scheme with isotropic dispersion finite-difference time-domain algorithm” IEEE Trans. Antennas Propag., vol. 54, no. 11, pp. 3505-3510, Nov. 2006), which is a novel low dispersion finite difference (FD) scheme. The formulation is derived for the scaling factors constrained with both the exact phase constant and cutoff frequency in the transverse domain, and for an optimal weighting factor using the least mean square (LMS) algorithm for the ID-FD equation.