An Unconditionally Stable Hybrid FETD-FDTD Formulation Based on the Alternating-Direction Implicit Algorithm

A novel hybrid finite-element time-domain (FETD) finite-difference time-domain (FDTD) formulation is presented. Numerical results show that the proposed method is stable even for very large time steps. Thus, from the implementation aspect, the method can be considered as an unconditionally stable scheme. The key to the successful hybridization of them is identical equivalence between alternating-direction implicit (ADI)-FDTD and ADI-FETD on rectangular mass-lumped elements. The stability and accuracy of the proposed method are validated by a numerical example. In addition, the proposed method has overcome some of the accuracy drawbacks of the pure ADI-FDTD method.