Wire above ground plane transmission line formulation in FDTD algorithm

Many structures of interest in electromagnetics contain thin conductors (PCB tracks, wires and microstrips), but characterising these conductors using the popular FDTD method is problematic. Thin wire formulations for FDTD, based on Holland´s method, do exist, but the structures being analysed have mainly been restricted to simple isolated wires. More realistic applications, including common features such as terminated transmission lines, have not, to the authors´ knowledge, appeared in the literature. In the paper it is shown that, to obtain accurate results for a terminated transmission line, extra effects have to be taken into consideration. A novel formulation is presented which combines the thin wire formulation based on Holland´s method and further consideration of local field distribution. Results are presented for the example of a simple transmission line with various resistive and other terminations, and it is shown that there is good agreement with analytical results.