Internal Resistance of Voltage Source by Use of the Finite-Difference Time-Domain Technique

The introduction of the internal resistance of a voltage source is a very effective method for analyzing the electromagnetic characteristics of antennas and microstrip devices by use of the finite-difference time-domain (FDTD) technique. However, some trial and error may be needed when choosing a resistance value to obtain a stable result. This letter proposes a method to obtain a proper internal resistance of a source voltage in a FDTD code. The key to this method is to choose a resistance value such that the voltage drop due to an internal resistance is less than the amplitude of a voltage source. The reductions of total computation time-steps are shown for various antenna types.