> But in rare circumstances, atmospheric refraction can cause high-frequency radio signals to propagate much farther than normal,
My uncle, decades ago, was a cop in rural Ontario (based on Kilaloe). Absolute middle of no where, mostly rural, but an area with a bit of elevation here and there.
Somewhere down in the US, Virginia I think, used the same frequency as them for their police radio. They discovered this because every now and then if you were up on a hill under the right weather conditions, they could talk to each other, hundreds of km apart. Very confusing the first few times.
Or so he tells the story. I'm neither a cop nor a person familiar with the magic of radio technology.
It is quite possible. I used to use packet radio on 144.45MHz, and when the conditions were right I could reach a BBS ~200km away. That's not terribly exciting, but both stations were pretty low to the ground, not very powerful or directional, and definitely not in line of sight.
For reference, according to wikipedia, if one station was at sea level and the other about 1500m above, you'd expect line of sight to be around 160km.
Similarly, around the same time of year (January or so) but less frequently we used to get VHF TV interference from a station on the same frequency but more like 1000km away (if I'm remembering the source station right, it was a long time ago), strong enough to interfere with the more local transmission.
One summer afternoon I was walking in the woods with a 2 meter handheld (140-144 MHz) and made a contact on somebody 200+ miles away across Lake Ontario (and land.) He was a Canadian who enjoyed tropospheric propagation events across the lake, particularly tuning into the My Network TV station in Syracuse which has an absurdly powerful transmitter.
My uncle, decades ago, was a cop in rural Ontario (based on Kilaloe). Absolute middle of no where, mostly rural, but an area with a bit of elevation here and there.
Somewhere down in the US, Virginia I think, used the same frequency as them for their police radio. They discovered this because every now and then if you were up on a hill under the right weather conditions, they could talk to each other, hundreds of km apart. Very confusing the first few times.
Or so he tells the story. I'm neither a cop nor a person familiar with the magic of radio technology.