Improved object definition within a TLM model for automotive applications

Traditionally transmission line matrix modelling (TLM) problems have been limited to using stepped boundary approximations. This is due to the conventional limitation that boundaries must be placed half way between nodes. This paper covers the application of smooth surfaces within a 3D model based on the symmetrical condensed node. The smooth surface technique used in this application is a novel approach which allows for boundaries to be placed at any point between nodes resulting in a smooth boundary definition. The paper covers, in detail, the results of the application of this method to a horn antenna. Differences between the results from smooth and stepped surface methods are highlighted. Comparisons to measured results, from the actual horn antenna being modelled, are also drawn