Theory of the Symmetrical Super - CondensedNode for the TLM

| This paper describes a novel time-domain node for the TLM method. It has the unique feature of modelling arbitrary inhomogeneous media on a generally graded rectangular TLM mesh without using stubs. Variations in material properties and arbitrary aspect ratios of mesh cells are modelled by allowing diierent characteristic impedances in a cell, maintaining impulse synchronism throughout the mesh. The complete theory of the new node is given and its implementation on a general TLM mesh is discussed. Numerical results for a canonical resonator loaded with dielec-tric layers are presented for diierent grading cases. Substantial savings in computer storage and run-time as well as improved accuracy compared to the uniform mesh are achieved when an appropriate non-uniform grading of the TLM mesh is used.