A Novel PLC Impedance Conditioning Technique for Quasi-Common Mode Power-Line Antenna Injection

摘要

In recent years, there has been a growing interest in the utilisation of in-situ power cabling for its antenna properties. Common-mode injection of signals further holds promise to facilitate effective low-power radiation from powerline antennas (PLAs) throughout a building. However, common-mode power-line communication (PLC) injection is illegal in many countries, for fears of interfering with the residual current device (RCD) protection. This paper reports on a novel impedance conditioning technique which makes use of a mains-rated ‘Y-cap’ and resistor to balance impedance levels in the Live and Earth conductors for improved PLC injection. The technique further improves power-line radiation by facilitating the flow of PLC current through the earth wire - in line with regulations. In general, earth return paths are asymmetrical to the other conductors and improved radiation is thus obtained when currents return through earth. Simulation results as well as experimental results are presented which confirm improved PLC injection as well as quasi-common mode earth current.