An accurate time-domain model of transmission lines with frequency-dependent parameters

Linear lossy two-conductor transmission line can be modelled as dynamic two ports in the time domain, via the describing input and transfer impulse re sponses. This convolution technique is very effective when dealing with net works composed of transmission lines with frequency-dependent parameters an d non-linear and/or time-varying circuits. The paper carries out an accurat e analysis of this model, in the most general case of lines with frequency- dependent parameters. For such lines it is not possible to evaluate analyti cally the impulse responses, nor is it possible to catch them numerically, due to the presence of irregular terms, such as Dirac pulses, terms that nu merically behave as Dirac pulses, and functions of the type 1/t(rho) with 0 < rho < 1. A simple method is proposed to evaluate exactly all the irregul ar terms of the impulse responses: once these irregular parts have been ext racted, the regular remainders are easily evaluated numerically. This metho d is applied to analyse lines with frequency-dependent parameters of practi cal interest, such as superconductor transmission lines, power lines above a finite conductivity ground, lines with frequency-dependent dielectric los ses and lines with normal and anomalous skin-effect. Numerical simulations are carried out for illustration. Copyright (C) 2000 John Wiley & Sons, Ltd .