Height helps a little but grounded radials help a whole lot more. Unless of course you have a long ground of sorts.
There are so many high profile elevated installs that I really wouldn't worry about it, it is nearly unavoidable to have something make up for the lack of direct ground. RF needs it and it will find it, typically though the negative and neutral leg of power. The audio line most likely won't attract much RF if you are using balanced connections.
I'm a big fan of both kinds of installs, but you can get more practical and unquestionable legal coverage with a ground install.
The people illegally broadcasting in French in my area is still at it after two, maybe three years (or more). Looking up NOUOs to see if they've been sent a letter yet (they haven't), I found this:
That can't be going far at all, maybe under 5 miles? So watch your numbers.
That was the field strength at 842 meters, not 3 meters. A pretty strong signal, well over legal limits. If you're getting 1/4 mile, particularly to a portable radio, you're well over legal limits. If you're very lucky with line of sight etc. and have a very sensitive car radio, you might (and I repeat might) get 600-800 feet, which is 1/8 mile or so (and that is really pushing it - it's not really useable range).
and it was a pretty nice setup. optimod 8000, harris ms-15, hombrew LPF, dual can bandpass cavity, 25mW to a 1/2 wave dipole but i have no real way to verify F/S is legal so i shut it down and it just sits here.
wish we had a easily obtainable 1-5 watt class license like our freinds to the north have.
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