A Three-Dimensional Transmission Line Matrix Method (TLM) In Cylindrical Coordinates

The TLM is a time domain numerical method used for solving a great variety of electromagnetic wave propagation problems. The space to be modeled is divided into discrete meshes. A good description of arbitrary geometry and boundaries remains a big challenge in electromagnetic modeling concerning the computer resources and simulation time. A Cartesian mesh can be used in TLM to describe a regular boundary. Curved walls are represented by piecewise straight boundaries by H. Meliani et al. (1988) which induce spurious modes that are not acceptable in some problems. In Cartesian mesh, the most commonly used node for 3D problem is the symmetrical condensed node SCN by P. B. Johns (1987) and its varieties. For the study of the propagation of electromagnetic waves in volumes having cylindrical boundaries, new cylindrical discrete meshes are investigated. The formulation and the scattering matrix for SCN with cylindrical mesh are presented. The accuracy of the cylindrical node and a comparison with the Cartesian node was exposed