FD-TD analysis of nonuniform multiconductor lossy lines

Transients in lossy nonuniform multiconductor lines are analyzed by the transmission line model (TLM) assuming quasi-transverse-electromagnetic (TEM) propagation. Voltage and current wave propagation is described by integrodifferential equations with variable coefficients, where a convolution integral between the transient impedance and the time derivative of the current is used to model the skin effect in the conductors. The resulting system of equations is solved by the finite difference time domain (FD-TD) method. An algorithm for the recursive calculation of the convolution integrals is proposed. Distributed nonuniformities, due to line parameter variation, and lumped nonuniformities, due to loads, junctions, and discontinuities, are considered