Mitigation of electromagnetic field radiated by PLC systems in indoor environment

Power line communication (PLC) is a well-known technique for data transmission over low-voltage power lines. The PLC signals have frequency bandwidth of about 1-30 MHz and they may cause electromagnetic interferences with services operating in the same frequency range. The regulation of electromagnetic radiation from PLC signals is currently subject of investigation in various international standardization bodies. This paper proposes a technique aiming at reducing the electromagnetic field radiated by indoor PLC signals, while not affecting the PLC signal itself. The basic idea is to take advantage of the additional ground conductor and inject a signal similar to the PLC signal into the ground-neutral line, but with a reversed phase. As a result, both the overall antenna mode- and transmission line mode-currents are significantly reduced, as well as the radiated electromagnetic fields. Experimental measurements are also carried out in a building and it is shown that the proposed technique allows for a significant reduction (up to 20 dB) of the PLC electromagnetic radiation in the considered frequency range (1-30 MHz)