Hi Paul; Something sort of resonant at that frequency eh; wiring is probably some multiple or sub-multiple of the metres of wavelength being transmitted? e.g. A quarter wavelength at say 20 metres (14 mhz.) is approx 16 feet!
Also there are so many electronic gadgets around these days; for example. When I am away my neighbour turns on at night, (and off each morning) my house lights from across the street, using a 'key-fob' device (probably around 350 mhz?). But once or twice we have found the lights switched off; we don't know how; possibly by some radio/taxi etc. going down the road late at night keying their radio?
Which leads me to a story about a radio amateur who was being checked out to ensure his equipment was transmitting on only the frequencies it was supposed to.
It was. And complied completely with the regulatory authority's (FCC etc.) technical requirements.
The problem was that it was an older housing area with numerous 'dodgy' wiring, older appliances, self hooked up TV sets and what have you and was these that were picking up the radio signals.
Finally after investigating many of the 'complaints' and recommending the fixing of many problems, they visited an elderly lady who said; "Oh yes I often listen in. It's very interesting I can hear his conversation 'ON MY ELCTRIC HEATER'.
Apparently there was a slight 'bad joint' in one of the connections which acted as rectifier (just like a crystal set detector), the coiled heater element was an inductance and the metal frame of the heater acted as a sound box. It all adding up to a suitable 'receiver' for waht was a relatively powerful radio signal nearby. She declined to have anything done to the heater!
Also there were a lot of problems with early TV sets because they could/would not properly reject signals outside the TV bands. Again no fault of the radio transmitters.
And I have a cheap hand held, none rechargeable shaver that creates chaos on any nearby radio! Shouldn't be allowed to be sold in my opinion!