A general characterisation procedure based on the extraction of a 2n-port a
dmittance matrix corresponding to n uniform coupled lines using the Finite
Difference Time Domain (FDTD) technique is presented. The frequency-depende
nt normal mode parameters are obtained from the 2n-port admittance matrix,
which in turn provide the frequency-dependent distributed inductance and ca
pacitance 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 e
xcellent broadband simulation tool for modelling and characterisation of mu
lticonductor coupled transmission lines.