Accurate transient simulation of transmission lines with the skin effect

An accurate method to simulate the transient response of multiconductor transmission lines with the skin effect is discussed. The presented method is based on the novel difference model approach reported by Kuznetsov and Schutt-Aine (1996). The difference model approach has been shown to be reliable, accurate, and highly efficient. However, the author recently observed that the original implementation of the difference model produces a significant error when the skin-effect attenuation is present. The error is mainly due to the failure of the rational function approximation that is used to generate the difference model for the propagation function. In this paper, the term related to the skin effect is analytically extracted from the propagation function along with the propagation delay, and then, the remaining portion of the propagation function is approximated as before. For the characterization of the skin-effect term, the normalized modal skin-effect attenuation function is preapproximated using highly accurate mini-max approximation. The resulting approximation coefficients can then be scaled and used for the transient simulation without any further approximation, providing accurate and robust characterization of the skin-effect attenuation.