Suggestions for FM Antenna Mounting


Hi All,

I recently got my MD ST-2 omnidirectional whip antenna mounted outside near the top of the roof and it's working pretty well overall. However, I'm now able to just barely pull in a couple stations that I would like to get more cleanly. (Couldn't get them at all before, so yes, I'm being greedy here.) A couple questions:

1) The roof is metal. Would mounting the antenna a few feet higher make any significant difference (by getting it away from the roof)? Would mounting the antenna to the metal flashing (i.e., grounding the antenna's base to the roof) help? If I want to put it on a tower or high pole, how much improvement might there be? I live on top of a hill already, so unless there is an issue about the ground being in close proximity, I'm not sure it will help much. It's currently about 12 feet off the ground, so would say 20 feet help? 30 feet?

2) Are there any omni antennas that are significantly better than the ST-2? I doubt it, but thought I'd ask. I'm hesitant to go to a directional antenna because I get stations from a lot of different directions and I don't want to bother with a rotator.

By the way, tuner is an MD Etude. I've also tried an inline signal amplifier without any luck. It makes the signal a little stronger on the signal meter, but doesn't improve the audio quality at all. Thanks for the help.
karls

Showing 3 responses by karls

The antenna is mounted to the eave right near the peak of the roof, so nearly all of it is above the roof. I was just wondering if anyone had any experience or knowledge of whether I would gain any range by raising it farther above the roof.
Sean, thanks for the great info and advice. This is exactly what I needed. You've got me thinking now, but unfortunately I don't have enough knowledge to take the next step. I can certainly install a mast/counterpoise and 90" is not a problem. My next question is, would a properly sized whip without a loading coil be better? How long should it be? 1/4, 1/2, full wavelength? I presume we're talking about a wavelength of 3 meters. Would I use the same 3/4 wavelength mast/counterpoise? What about base termination and the connection from the base of the whip to the 75 Ohm coax? I assume a special geometry is required to maintain the impedance continuity at that point. Or can I just run the end of the whip right into a male coax connector and be done with it? I can machine just about any geometry that would be needed out of any material that is required, if necessary.

If there are any good practical texts that you can recommend, I would appreciate it. I have a good background in physics so I don't mind math. Thanks again.
Sean,
Excellent. I'm going to try this asap (which may be weeks) and put it as high as I can reasonably get it, and I'll give you feedback as soon as I get it running. One other question: Does the presence of trees have any significant influence on the signal? I don't want to bury it in a deep dark forest, but there are a few trees around the house that I'd rather not try to get above. (Not only to keep the tower height reasonable, but also to minimize the risk of lightning strikes.) Thanks again for the help.