Quasi Static Correction of a Knife Edge Corner in 2D TLM Algorithm

L. Cascio, G. Tardioli, T. Rozzi and W. J. R. Hoefer

12th Annual Review of Progress in Applied Computational Electromagnetics, pp 317-324, Monterey, California USA, March 18-22 1996.


Numerical techniques such as TLM and FDTD are used presently to solve a large class of electromagnetic problems. However, a common drawback of these techniques resides in the difficulty to accurately describe structures in the presence of fine features such as sharp corners, where singularity of the electromagnetic fields is encountered. In this paper a local modification of the 2D-TLM algorithm for the nodes surrounding a knife edge is proposed. The Green's function for a semi-infinite knife edge is evaluated under a quasi-static approximation and used to derive an equivalent circuit of the corner, characterized as a three-port device. The method is tested by evaluating the resonant frequencies of a 2D septum-coupled cavity. An accurate value for resonant frequencies of the cavity is extracted by Richardson extrapolation for increasingly fine resolution. The resonant frequencies obtained with the corner correction algorithm for different discretizations are finally compared with the extrapolated results.

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