The unconditionally stable one-step leapfrog ADI-FDTD method and its comparisons with other FDTD methods

One of the major hurdles that prevent the recently developed alternating-direction-implicit finite-difference time- domain (ADT-FDTD) method from being widely used is its relatively large computational expenditures due to its sub-step computations. To address the issue, a reformulation of the unconditionally stable one-step leapfrog ADI-FDTD method and its comparisons with other FDTD methods are presented in this letter. It is found that the one-step method requires less amount of memory and CPU time than the current unconditionally stable FDTD methods and the similar memory requirement and less CPU time (when the time step is chosen to be adequately large) than the conventional FDTD method. In other words, when the unconditionally stable FDTD methods are required to solve electromagnetic problems, one is strongly recommended to use the one-step leapfrog method presented.