Transmission Line Theory

This chapter describes three key approaches that are used for the analysis of transmission line problems the Telegrapher's equation, the Smith chart, and flowgraph analysis using Mason's rule. The purpose of a transmission line is to transfer a signal from a source over some distance to a remote load. The characteristic impedance and propagation constant are used in practice to represent the electrical behaviour of a transmission line. A most important effect is that impedance is found to be a function of position along the transmission line, leading the use of the Smith chart to perform calculations. Transmission lines obey Kirchhoff's laws and can be analysed with them provided that the time delay is taken into account. The chapter also introduces transmission line behaviour in terms of delay time and pulses, and the effects are important when the propagation delay of the line is comparable to the duration of the pulse.