A generalised transmission line method for analysing electromagnetic structures including active, non-linear and diespersive media.

Principal Investigator: Professor C Christopoulos

Starts: 1 October 1994
Ends: 30 September 1996

Value: £74,466

The objective of this project is to develop a method for analysing, in the time domain, general electromagnetic structures including non-linear, active and dispersive media. No restrictions on the type of structures should be imposed and radiating and absorbing boundaries are included. Although the method is aimed at time domain analysis, frequency domain analysis can be easily achieved by using harmonic inputs since there will be no restrictions on the number or type of input signals. Two and three-dimensional structures will be analysed. Progress: This is a collaborative project with the University of Kent. The description below refers to work at Nottingham University. The research assistant, Chris Smartt, joined the project after working in the microwave area. He had no previous experience of the TLM method so he spent sometime in becoming familiar with the suite of three-dimensional field modelling software developed at Nottingham. During this learning and familiarisation process he also introduced enhancements to the available code to permit more efficient extraction of s-parameters. A visit to Kent University was arranged to discuss the work schedule and as a result a number of specific configurations for initial study were identified. These are a microstrip line, an asymmetric two-line microstrip and a low-pass filter. The Kent requirements from the TLM code were defined and the first configuration was studied up to a frequency of 200GHz with particular emphasis on the precise parameters of the field termination. From these simulations equivalent circuit termination parameters (amplitude and phase) as a function of frequency were determined. The results are being prepared for transmission to Kent for interfacing with their lumped-component TD solver. Work has started on looking at the more complex configuration and the use of multigrid techniques to increase accuracy and control computational requirements.