Transmission line matrix modelling of microwave circuits and structures

214 p.The Transmission Line Matrix (TLM) method was first proposed by P. B. Johns [1] in 1971. TLM is a simulation technique which sets up an equivalence between elec-tromagnetic field and transmission line parameters such as voltage and current. In its typical form, TLM is a time-domain numerical method based on the differential form of Maxwell's equations, and belongs to the same class of numerical techniques as time-domain finite-difference (FDTD) and finite element methods. However, the TLM method differs from the others in that its formulation is based on the wave propagation properties of electromagnetic fields, obedience to Maxwell's equations in particular being enforced subsequently during the theoretical derivation of the method. Application of the method requires that the problem space to be simulated be discretized into a 2D or 3D mesh or "matrix" of transmission lines. Three steps [2] are usually involved in the TLM algorithm: First of all, the source, e.g., an incident plane wave, is transformed into voltage pulses on the transmission lines. Then the evolution of the source disturbance within the mesh is implemented in terms of scattering and transfer events [3], which actually simulate Huygen's principle of wave propagation.RP 29/9