Are HomePlug adapters really that large a source in practice, though? I'm an amateur operator and I've spent no small amount of time messing with HomePlug adapters and various bits of equipment to measure interference. Yes, they do produce very broad noise when the network is in use (although mine, and the internet suggests many others, intentionally filter output near amateur and other in-use HF bands).

That said, I think that these devices are actually quite rare in the real world - most people don't even seem to know what they are - and in my testing the noise dissipates very quickly as I leave my house, disappearing into the background of the city after only 20-30 feet.

I think that regulators have definitely dropped the ball on HomePlug, but I also don't think that it's that much of a problem, particularly given that it's been a commercial failure. Most of the ire towards HomePlug comes from people being upset about commercial-scale BPL installations, which actually have the potential to be a major problem over a large area.

In my house, my monitors actually account for more problems I experience than the HomePlug adapters do, in my everyday radio usage. And they aren't even cheap knockoffs, they're pricey name-brand models.

It depends what country you live in. In the UK, BT Broadband, the largest ISP, hands them out for free (or used to) so they're reasonably common.

What about those adapters causes the issue? Is it the devices themselves emitting radiation? The cabling in a house?

The cabling radiates like crazy at those frequencies.

Interestingly enough, there is enough radiation that you don't really need an actual connection. Someone put one of the endpoints in a field with a generator and got a connection to another endpoint. In a sense power line adapters are just using radio over the air.

Sending data over a power line, even at low bit rates is very difficult to do reliably. So all the radiation is in a sense a feature in that it improves connectivity. Not so much a feature to those who have an actual licence to use those frequencies...

The powerline adapters works by transmitting signal over house wiring, and the wiring is effectively creating an antenna. So depending on which frequencies the adapter uses, will potentially radiate the same frequencies and the harmonics.

I'm missing something, can you help me understand?

Wouldn't ethernet cables have the same issues? Does the increased power flowing through power lines somehow amplify the signal? Is that pretty much the definition of what a power amplifier in a radio does, add juice to a signal on an antenna so it gets broadcast further?

Ethernet cables are twisted to minimize this effect. See https://en.wikipedia.org/wiki/Twisted_pair

Whoa, cool, I never thought of that!

Does the amount of wattage going through the line effect how "loud" the interference is?

Electrical wiring in your home used to pass data (as a side effect) acts as a large antenna/transmitter.

Just to clarify, as someone seeing "instead of wifi" and "acts as a large antenna" from the parent comments may come to an incorrect assumption.

In PLC (power-line communication), wiring is not meant to act as antenna. All transceivers are wired. It's an undesirable, unintentional side effect of limited (to the extent of complete lack of) cable shielding - because, well, power lines are usually meant for different application than data transfers.

Thanks for replying and pointing that out. I've corrected my comment.

So am I basically broadcasting my data to anyone nearby with a receiver?

They're encrypted (or should be), so no.

"Grow light" ballasts and solar charge controllers are big ones too.

Is there a reason they don't mess with UHF? Studying for my ham exam as we speak.

Because they don't operate in the UHF bands' frequencies. https://en.wikipedia.org/wiki/Broadband_over_power_lines#Imp... says "0-30MHZ" (that's the HF bands) "and sometimes as high as 80Mhz" (50Mhz would be 6-meters)

UHF does not propagate through power lines, the frequency is too high.