Enhancing the FDTD with asymptotic methods to solve large problems

In this paper, we describe a new approach to dealing with electrically large problems in the context of the FDTD method. The method we propose utilizes the underlying concepts of the asymptotic method to identify the physical optics and diffraction "type" contributions in the time signature at an observation point, which may be located either on or close to the object. The time domain response is derived by using FDTD, with either a Gaussian, or a modified Gaussian pulse excitation. We show that using these sources, it is relatively straightforward to identify and isolate various contributions from the edges, as well as the creeping and traveling wave currents by using the arrival times as the gauges for the distances from the sources of these contributions, not unlike the way it is done when one uses a TDR.