The wired channel model, including the power line communication (PLC) one, is often derived using the voltage gain, i.e., the ratio between its output and input voltages. Although this modelling approach offers information, it is often incomplete and can be dependent on the front-ends and connections used to measure such a channel. To overcome this limitation, this paper discusses how an invariant channel model can be defined and retrieved, i.e., a model that completely and intrinsically describes the transmission medium and that is not affected by the boundary conditions, e.g., the hardware blocks that are necessary to carry out measurements such as the couplers and cables used in PLC. In this paper, we firstly describe the theory that stands behind the problem, and then we validate it with numerical results in a real wired communication scenario.
