Study of Low-Dispersion ADI-FDTD Method With Isotropic Finite Difference

An isotropic alternating-direction-implicit finite-difference time-domain method (IADI-FDTD) with low numerical dispersion error is presented. The isotropic finite-difference templates are introduced to approximate the spatial differential in the ADI-FDTD method, and the normalized phase velocity is adjusted to eliminate the numerical dispersion error. The investigation shows that IADI-FDTD can nearly achieve zero dispersion for a single frequency, and the numerical dispersion error is dramatically decreased compared to the ADI-FDTD method for a finite bandwidth.