Physical Interpretation of Reflection and Transmission in Lumped Systems

In lumped systems, traveling waves do not occur, in principle, because lumped elements are characterized as one-ports interconnected by ``wires'' having no time delay associated with them. It may therefore seem strange that a scattering theory formulation exists for lumped networks.

There does exist, however, a physical interpretation of reflection and transmission in lumped networks [34]. Suppose we have a ``force source'' which drives a ``load impedance'' in series with a ``source impedance'' . For simplicity, let the load and source impedances be real (dashpots) as shown in Fig. L.20.

An equivalent electrical circuit is shown in Fig. L.21.