Accurate implementation of current sources in the ADI-FDTD scheme

This letter presents a new method of implementing current sources in the alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method. The current source condition is derived systematically, starting with the fully implicit Crank-Nicolson (CN) FDTD scheme for Maxwell's curl equations and building the ADI-FDTD scheme as a second-order-in-time perturbation of the CN-FDTD scheme. We demonstrate that the accuracy of this new source condition is superior to previously proposed techniques.