Here's the problem, gang. I know some of you have read this ad before and knew enough to simply poopoo it off right away.
The trouble is we're getting questions from people that *believe* what is advertised.
The item of which I speak is the amasing "Ultimate FM" antenna foisted upon the uneducated by Radio Brandy.
http://www.radiobrandy.com/FMAntenna.html
This antenna is SO amazing that it DEFIES THE LAWS OF PHYSICS! Anyone with even the most minimal knowledge of radio signals immediately knows that this advertisement is complete and utter bold face lying. First of all most of their testimonials are clearly from people who can't possibly be legal. Unless of course they're actually running a 7 watt transmitter that is running so poorly, and with the system so ineffeciently designed that they are still managing only the legal 250uv/m @ 3 meters.
What needs to be simply and clearly stated, for all those who inquire about the amazing comverage they expect to get using this "Ultimate FM Antenna" is that if they are Part 15 legal, meaning no more than 250uv/m @ 3 meters their signal is not going to be listened to at a mile away. Or a half mile away. It may indeed be possible to be a mile away with an incredibly sensitive field strength meter, with a good, external, directional antenna, and be able to find the signal and take a reading and come up with something ridiculous like 0.0000000675 uv/m that has been mentioned in other posts, but really that number is so far down into atmospheric noise that it doesn't even matter. That's so far down below anything receiveable by even the best radio built that it just doesn't matter. The fact that a super weak signal may be identified doesn't mean it's "coerage area" or that it can be heard by a radio.
The ad for this antenna is clearly violating every possible rule for advertising. It's like saying "Your 1986 Buick that gets 16 miles per gallon will get 1600 miles per gallon when you put on these Ultimate Mileage Tires". It's just not posible, folks. It's not a matter of if engineers agree, it's a matter of being able to change the laws of physics. And as Scotty once said "Aww Jim, I cannot change the laws of physics".
So many who get interested about Part 15 do a little web searching and come across the Radio Brandy web site and get sucked in by this and it bugs me.
Bottom line, ladies and gentlemen, is if you are at 250uv/m at 3 meters no change in antenna is going to get you more coverage. If you put up some sort of gain antenna and are 250uv/m at 3 meters in the sweet spot, the rate that signal strength drops off at greater distances remains the same. If you invent a magical antenna that gives you 250uv/m at 3 meters, and also at 4 meters, it would NOT BE LEGAL.
The Ultimate FM Antenna advertisement on that web page is chock full of out and out lies, wives tales and fantasy. Apparently they spent an amazing 17 years desiging a copper dipole. I built my first amazing copper dipole when I was 11 years old. That was in 1969. I would have gladly shared my notes with them and saved the all that time figuring it out.
Tim in Bovey
AKA "Mythbuster"