2D ADI-FDTD Method Based On isotropic dispersion finite difference scheme

Since first introduced by T. Namiki (1999), the standard ADI-FDTD (Alternating- Direction Implicit Finite Difference Time Domain) method has been applied to various areas of computational electromagnetics. The ADI-FDTD has an advantage of unconditional stability, but suffers from larger anisotropic dispersion than the standard explicit FDTD. Thus, despite of unconditional stability, the accuracy is dramatically deteriorated when the time step of the ADI-FDTD is increased beyond a certain level. Hence, developing a FDTD scheme with lower dispersion has been one of the most important issues among many researchers [M.K. Sun and W.Y. Tam, 2006]. In this paper, we propose a novel ADI- FDTD scheme, ADI-ID-FDTD method that greatly reduces numerical dispersion errors. The proposed scheme is based on an isotropic dispersion finite difference (IDFD) scheme that was successfully adopted in an explicit FDTD scheme [I.S. Koh et al., 2006]. Properties of the proposed scheme such as dispersion and stability are investigated.