General ADI-FDTD Formulations for Multi-Term Dispersive Electromagnetic Applications

General formulations of the alternating direction implicit finite difference time domain method are presented for modeling multi-term dispersive electromagnetic applications. The proposed formulations, which are based on the exponential evolution operator scheme, allow modeling different types of frequency dependent materials in the same manner and can be easily incorporated with the nearly perfectly matched layer absorbing boundary conditions to model open region problems. 2-D numerical example is included to show the validity of the proposed formulations.