Mode-Port-Network Approach to Analyze Power-Line EMC Problems for PLC

In Japan, a power-line communication (PLC) is in use as an indoor system in the frequency band of 2 MHz to 30 MHz. However, the radiated emission in this frequency band, which is caused by the common-mode current generated in the power-line systems, is a serious matter. To analyze the high-frequency behavior of the line system, a two-port-network model using differential-and common-mode ports is proposed here. As an example, the network-function expression is effectively used to analyze characteristics such as longitudinal conversion loss (LCL), induced common-mode currents in a power line having a load circuit, and an impedance stabilization network 1 (ISN1) attached to a PLC modem.