Discrete and Modal Source Modeling with Connection Networks for the Transmission Line Matrix (TLM) Method

We present a technique for the modeling of discrete and modal sources in the transmission line matrix (TLM) method by means of connection networks. Discrete sources are modeled with connection networks based on parallel and series adaptors of wave digital filters (WDFs). Modal sources are modeled with an ideal transformer network. The scattering matrices of the connection networks are given and their properties are discussed. In a numerical example we show that we could calculate accurately the input impedance of a bowtie antenna using a discrete source with an impulsive excitation. In this way we were able to characterize in the shortest possible time the antenna structure in the whole frequency range. The result of the computation is compared with known measurement results and known simulation results from the literature and shows good accuracy.