the transmission mixed-mode scattering matrix. Moreover, MIMO PLMs usually communicate through two transmit ports, since only two linearly independent voltage differences can exist between the three conductors of a power line cable. Hence, it make sense to consider the whole PLN to be composed by two input and two output elements.

Using the same approach, each network load can be also represented with a 4-port configuration, as depicted in , which allows a separate representation of the DM and CM impedances. We point out that $Z_{DM-load}$ in is different for different type of loads. In fact, while three phase loads are entirely characterized by $Z_{DM-load}$, single phase loads can be simply described by one of the three impedances $Z_{L_{1\cdots 3}}$, while the other two account for parasitic effects. Finally, PLMs impose two DM impedances on the network termination. The $\bm{S}$ matrix of each load can be in general computed referring to . In this paper, we report the result obtained for a single phase load characterized by $Z_{L_{1}}$. The scattering matrix referred to $Z_{L_{1}}$ is

$$\begin{aligned}
&\bm{S}_{L_{1}} =  \notag \\
&\begin{bmatrix}
\alpha                              & (1+\gamma)\sqrt{\frac{Z_2}{Z_1}}  & \epsilon (1+\delta)               & \epsilon (1+\eta)                 \\
(1+\alpha)\sqrt{\frac{Z_1}{Z_2}}    & \gamma                            & \epsilon (1+\delta)               & \epsilon (1+\eta)                 