Concise Current Source Implementation for Efficient 3-D ADI-FDTD Method

A concise current source implementation is presented for the unconditionally stable 3-D alternating direction implicit finite-difference time-domain (ADI-FDTD) method. Unlike the conventional implicit symmetric source scheme applied in both updating procedures, the new implementation involves implicit current formulation in the first procedure only. Note however that the resultant accuracy does not deteriorate but remains to be identical as before. This is achieved using our recent efficient algorithm for the 3-D ADI-FDTD method. Moreover, the current formulations applied in both procedures therein are simplified, along with further reduction of the floating point operations count for the main iterations. Analytical validation of the equivalence among conventional implicit symmetric source scheme and our efficient algorithms with alternative current implementations are discussed. Numerical results provide closer scrutiny of the asymmetry errors, which may still exist even with symmetric source.