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In Reply to: I don't know who it was that suggested vertical mounting of a dipole. posted by Todd A. on November 23, 2006 at 14:47:27:
Is there any noteworthy of your situation that makes it unusual?
Is the terrian around you hilly, you live in a valley, etc?
Most stations use circular polarization with equal horizontal and vertical power. So in theory it should not make a difference. But there have been comments that the vertical part may carry better over hilly terrian.
Follow Ups:
Most likely it was the signal orientation of the stations antenna. Nowadays people listen to FM more in their cars than in their homes...and cars use vertical whip antenanas. So stations are more concerned with getting good reception "thataway" than with traditional antennas. I've found the same thing orienting a dipole in my living room....although I've ended up with a horizontal outdoors.
Harry
Signal orientation of the station? Same holds true for transmission & reception; verticals are omni-directional & horizontals are directional. A vertical FM tranmitting antenna can simply reach a wider-dispersed audience but it has absolutely nothing to do with signal polarization or automobile antennas (remember the automobile FM antenna used to be a dipole imbeded within the windshield).
you guys need to come up to speed on circular polarization, used by almost all stations so they transmit in both horizontal and vertical planes. Look at the FCC database for the station's antenna being used.
This has been going on for a long time.
I was actually unaware that REAL stations are doing that, but it makes sense they would when the money is there. I have a good excuse though since this radio stuff is mostly just a hobby for me. How is this accomplished, antenna arrays?I find your statement from an earlier post about one orientation being more likely to propagate well in the presence of hilly terrain fascinating. Any idea what is going on here? Perhaps this has to do with the permeability/permitivity of the ground plane, eh?
It's done with a circular polarization FM broadcast antenna. from this site, for instancehttp://www.scott-inc.com/html/fmant.htm
"Polarization.Originally the fm service was slated to be horizontally polarized. This worked best with horizontal antennas. Station power level is still considered to be that which is radiated in the horizontal plane. Later the commission authorized stations to use an equal amount of power radiated in the vertical plane. By controlling the phase relationship of the two radiated planes, a rotating or circular polarization is created. This is compatible with both horizontal and vertical receive antennas. The quality of the circular polarization is the horizontal to vertical energy balance, or axial ratio, and should ideally be one to one. This is rarely achieved with side-mounted fm antennas in all directions. Does perfect axial ratio make much difference? I suggest that it does not."
For the FCC database, start here, put in the call letters, then click on the blue call letter link for engineering data.
http://www.fcc.gov/mb/audio/fmq.html
I think the dude may have just been implying that the OP may want to try different antenna orientations which seems like good advice considering that there most certainly is an orientation of an EM wave which has nothing to do with antenna radiation patterns. If the antenna does not work in one orientation and is pointed directly at the station, try turning the antenna orthoganally and the result may be better reception, this would be due to the orientation of the EM wave, ie is E or H (or neither)field parallel with ground plane (earth surface). This can be especially true when trying to pull in skip, since the reflective surfaces are typically some randomly oriented feature in nature.
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