INFLUENCE OF THE LINE CHARACTERIZATION ON THE TRANSIENT ANALYSIS OF NONLINEARLY LOADED LOSSY TRANSMISSION-LINES

The analysis of nonlinearly terminated lossy transmission lines is add ressed in this paper with a modified version of a method belonging to the class of mixed techniques, which characterize the line in the freq uency domain and solve the nonlinear problem in the time domain via a convolution operation. This formulation is based on voltage wave varia bles defined in the load sections. The physical meaning of such quanti ties helps to explain the transient scattering process in the line and allows us to discover the importance (so far often overlooked) of the reference impedance used to define the scattering parameters. The com plexity of the transient impulse responses, the efficiency of the algo rithms, and the precision of the results are shown to be substantially conditioned by the choice of the reference impedance. The optimum val ue of the reference impedance depends on the amount of line losses. We show that a low-loss line can be effectively described if its charact eristic impedance or the characteristic impedance of the associated LC line is chosen as the reference impedance. Based on the physical inte rpretation of our formulation, we are able to validate the numerical r esults, and to demonstrate that, despite claimed differences or improv ements, the formulations of several mixed methods are fundamentally eq uivalent.