Impedance matching with low-cost, passive components for narrowband PLC

The impedance variation in power-line networks is a well known problem in power-line communications (PLC). These variations arise when different electric loads are connected and, or disconnected to the power line network at different times. This causes a problem in trying to achieve maximum power transfer, hence the need for a matching circuit. Previously we investigated transformerless power-line coupling circuits, with a view of simplifying the design and minimizing costs. Therefore, we used only passive L-C components. The second step of this project is to design an accompanying adaptive impedance matching network. The main objective is to improve on mismatch power-losses, while at the same time it must be an economical solution. In this paper we outline basic impedance matching procedures and the necessary power-line environment considerations. The design of some typical passive impedance matching circuits for narrowband PLC is also discussed. We further investigate the suitability of such a network in a low-voltage residential power-line network.