New Horizons in Numerical Time Domain Modelling of Microwave Structures

In this paper, a number of new developments in time domain modelling of electromagnetic fields and their potential impact on computer-aided design of microwave circuits will be described. After a brief discussion of general field modelling issues, and a brief summary of Transmission Line Modelling (TLM) techniques, several novel TLM concepts and procedures which allow the modelling of frequency dispersive boundaries in the time domain, will be presented. They are opening new possibilities for the large-scale numerical preprocessing of substructures, the partitioning of large time domain problems at the field level, and for combining other numerical techniques with the TLM method. Finally, several applications of these concepts to microwave and millimeter wave CAD will be demonstrated, and some thoughts on the future evolution of field theory based design methods will conclude the paper.