Introduction to the modelling of wave propagation using TLM

Transmission line matrix (TLM) modelling was developed in the early seventies, and the paper by Johns & Beurle (1971) contains most of the concepts required for an understanding of the method. It was first used for the investigation of electromagnetic wave propagation and later for other electronic and electrical problems. It has been applied to a wide variety of wave propagation problems in homogeneous and inhomogeneous media, including electromagnetic compatibility studies of motor vehicles and the modelling of semiconductor lasers. TLM is a method which physically models wave propagation and is ideally suited to simulating sound waves travelling through a medium. In the original work on TLM in electromagnetics, the properties being modelled were voltage and current. The equivalent quantities in acoustics are velocity and either displacement or pressure. The TLM method can be applied in one, two or three dimensions