Extraction of multiple coupled line parameters using FDTD simulation

A general characterisation procedure based on the extraction of a 2n-port admittance matrix corresponding to n uniform coupled lines using the finite difference time domain (FDTD) technique is presented. The frequency-dependent normal mode parameters are obtained from the 2n-port admittance matrix, which in turn provide the frequency-dependent distributed inductance and capacitance matrices. To illustrate the technique, several practical coupled line structures, including a three-line structure, have been simulated. It is shown that the FDTD-based time domain characterisation procedure is an excellent broadband simulation tool for modelling and characterisation of multiconductor coupled transmission lines.