PLC turns the wires into giant antennas
Communication is normally transmitted on cables designed for it. Examples are telephone cables, coaxial cables and cables for computer networks. These are all designed to limit the radiation from the signals.
The electrical wires in homes and businesses, as well as the power lines along the streets are not designed to carry communication signals. Here, the PLC signals turn the wires into giant transmitting antennas. This is caused by the modification of the electrical and/or magnetic fields created by the PLC signals.
The utilities claimed that there is no such “antenna effect”, but when radio amateurs complained about interference with their radios, the U.S. Federal Communications Commission (FCC) looked into the matter. The FCC Laboratory did measurements on seven PLC systems, and found that all seven of them radiated. Three of them even radiated at or above the radiation limits.1,2 Those PLC systems were not used for smart meters, but the principle is the same.
Government agencies in Japan and several European countries also found that PLC systems turn power lines into transmitting antennas.3,4,5
The British Broadcasting Corporation documented that household wiring can also radiate PLC signals.6
Please see reference 5 for a more detailed coverage of this antenna effect. It also provides many additional references, including several articles from engineering journals.