Lossy Multiconductor Transmission Lines

This chapter discusses the characterization of uniform lossy multiconductor transmission lines as multiports in the time domain. The chapter deals with lossy lines with frequency-independent parameters, followed by the analysis of parameters depending on the frequency. As with lossy two-conductor lines, the impulse responses, characterizing the equivalent multiport in the time domain, contain highly irregular terms that are “unbounded” and cannot be handled numerically. As was done for lossy two-conductor lines with frequency-dependent parameters, these difficulties may be overcome if the asymptotic expressions of the describing operator in the Laplace domain are known. A general method that is simple and elegant is proposed in the chapter to evaluate the asymptotic expressions of the describing operators. The method is based on the perturbation theory of the spectrum of symmetric matrices and can be easily and effectively applied to the most general case of frequency-dependent lossy multiconductor lines. This chapter describes this method in detail and applies it to obtain the analytical expressions of the irregular parts of the impulse responses.