On the modeling of conductor and substrate losses in multiconductor, multidielectric transmission line systems

Most models used for the analysis of lossy, multiconductor, multidielectric transmission line systems (MCMDTLSs) are noncausal and fail to accurately predict the signal distortion on practical printed circuits. The authors review the method of analysis and assumptions made in these models and present more accurate models. The authors solve for the time-domain response of a single, lossy, perfectly matched conductor above a ground plane and immersed in a perfect dielectric, assuming transverse electromagnetic (TEM) propagation. The authors also solve for the same line, except that the line is assumed to be perfect while the dielectric is lossy. The TEM mode propagates in such lines and no errors result from this assumption. A brief generalization to MCMDTLSs is described to illustrate the theory, and numerical examples are presented.