Reduction of numerical dispersion of adifdtd method with quasi isotropic spatial difference scheme

In this paper, the di®erence scheme of the alternating- direction-implicit finite-difference time-domain (ADI-FDTD) method is replaced by the quasi isotropic (QI) spatial difference scheme to improve its numerical dispersion characteristics. The unconditional stability advantage of QI-ADI-FDTD is analytically proven and numerically verified. The numerical dispersion of the novel method can be dramatically reduced by choosing proper weighting factor. An example is simulated to demonstrate the accuracy and effciency of the proposed method.