Loaded transmission line as a two-port network

A college homework problem, dealing with a loaded transmission line, is reviewed. The setup is then treated as a two-port distributed network. The law of conservation of power is explained with the aid of a scattering theory. Two coupled circuit relations are then formulated. One, associated with the load terminals, is quite different from the conventional equation involving the self impedance and the mutual impedance. An effective impedance function, designated as the scattering impedance, is introduced to facilitate the formulation. The result of applying the Rayleigh/Carson reciprocity theorem to find the expression of the load current is also discussed