Delayed impedance models of two-conductor transmission lines

This paper presents a new delayed model of two-conductor transmission lines with frequency-independent per-unit-length parameters. In particular, the line delay extraction problem is considered. By use of a dyadic Green´s function macromodel method, the rational form of the open-end impedance matrix allows an easy identification of poles and residues, and a new technique for the extraction of the line delay in an analytical way is gained, without any impact on the complexity of the line macromodel itself. By use of Laplace and Fourier transforms, the transfer function is expressed in terms of the Dirac comb. The delay is then easily identified and directly incorporated into the system impulse response. Giving a current-controlled representation, the port voltages are evaluated. Thanks to the formulation of the transfer function by use of the Dirac comb, the convolution product is avoided, gaining accuracy and time-saving from a computational point of view. Numerical results confirm the validity of the proposed delay-extraction technique. The basic ideas for the extension of the proposed technique to the lossy case are outlined.