Canadian unlicensed AM regulations for broadcasting state that you can have a maximum field strength of 250uv/m at 30 meters.
I know that it has been discussed in previous threads what the field strength would be for a ground-mounted 100 mw transmitter - but I can't find those threads in a search (perhaps I'm just not using the right keywords). In any event, does anyone have that number available? I'm just attempting to decide whether it's worthwhile to attempt to use AM or not in my new location.
[Canadian rules for unlicensed BROADCASTING (BETS-1, 5 & 6) are different than those for unlicensed non-broadcasting applications (governed by RSS-210). There is no 100 mw rule for unlicensed AM broadcasting, and it is governed by field strength alone. Interestingly, the rules for unlicensed FM are slanted in favour of broadcasting - RSS-210 only allows a field strength of 250uv/m at 3 meters, whereas BETS allows 1000uv/m at 3 meters or 100uv/m at 30 meters).
This mess of rules is ignored by the transmitter manufacturers, and quite often by low power broadcasters here. I've never heard of anyone being shut down for broadcasting using an RSS-210 certified transmitter running at 100 mw, but the rules state that it is certainly possible. In fact, I've never heard of ANY enforcement actions here in Canada with unlicensed AM, other than obvious pirates.]
Artisan, I don't recall anyone posting actual field strength measurements for ground mounted AM antennas, probably because it would depend so much on antenna design, ground radials, soil propagation and so on.
This post by PhilB, inventer of the AMT5000, describes the antenna/ground arrangement known to give the best results.
http://www.part15.us/forum/part15-forums/general-discussion/ultimate-part-15-am-installation
"What the field strength would be for a ground-mounted 100 mw transmitter."
A simple question for which there is no simple answer, unfortunately. But here are some examples showing about what to expect for the conditions shown.
There are thousands of possible variations for the values in the first three columns below. Probably all of them are inaccurately known -- even by manufacturers of the transmitters designed and used for unlicensed systems.
Thanks. Just what I was looking for. It just confirms what I thought - that FM is the way to go in Canada for (legal) unlicensed broadcasting.