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Horizontal Polarization for FM Broadcast. Time to end this antiquity

R

RF101

"47 CFR § 73.316 - FM antenna systems." forces FM commercial broadcasters to use at least horizontal polarization, although elliptical and circular varieties obviously are alllowed. NCEs, translators, AUXs, and LPFMs are permitted vertical-only I understand.

Is not it time to dump the legacy H-only polarization? Home stereo listeners with 300-ohm folded dipoles seem to be ancient history. Yes, I know there are some fringe cases where interfering translators can be nulled out with receiver antenna polarity changes. Still, a V-only situation may offer some windload/weight advantages over an H-only situation while maintaining the lower power consumption profile.

Give me commercial V-only! I guess it's time to petition the FCC.
 
RF101 said:
"47 CFR § 73.316 - FM antenna systems." forces FM commercial broadcasters to use at least horizontal polarization, although elliptical and circular varieties obviously are alllowed. NCEs, translators, AUXs, and LPFMs are permitted vertical-only I understand.
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NCE stations can use circular polarization or vertical polarization, at the applicant's option. There are certain rules around how polarization should be treated with respect to NCE spacing rules, outlined in 47 CFR 73.501.

I'm 99% sure 73.316 applies to all full-power FM broadcast users, including Aux facilities.

From experience, I know translators are also permitted to use vertical polarization, although I'm not sure if that authorization comes from 73.316.

Please cite the rule you think prohibits vertical polarization before you go petitioning the Commission.
 
Per the regs...

"§ 73.316 FM antenna systems.
(a) It shall be standard to employ horizontal polarization; however, circular or elliptical polarization may be employed if desired. Clockwise or counterclockwise rotation may be used. The supplemental vertically polarized effective radiated power required for circular or elliptical polarization shall in no event exceed the effective radiated power authorized."

That's the source. Do you know of any full-power FM commercial stations runninh V-only polarization? If so, let us know..
 
You included a contradiction in the question and I didn't catch it when replying.

Is not it time to dump the legacy H-only polarization?
Click to expand...
Give me commercial V-only! I guess it's time to petition the FCC.
Click to expand...

I responded to the first one. H-only hasn't been the rule for decades for any full-power license.

V-only is not permitted. As far as I know, every FM (commercial and non-commercial) must have at least 1 watt H-pol (example: WHZN with 1 watt Hpol, 7.8kW Vpol)
 
As I understand it some noncoms in the very lower end of the band near channel 6 TV were allowed to go V only to reduce interference with the TV channel. Once that station had been given permission and had operated V if it moved up the band it could continue to operate V because it had the previous permission. That's what happened with a station I work on.
 
While H-only is not a "smart" option it is still a legal option if I understand correctly. Obviously stations want to operate in circular-fashion in urban markets with tall buildings or other obstructions. In more rural areas power savings may come into play.
 
RF101 said:
While H-only is not a "smart" option it is still a legal option if I understand correctly. Obviously stations want to operate in circular-fashion in urban markets with tall buildings or other obstructions. In more rural areas power savings may come into play.
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The H only antenna is very poor for car reception. I had a station that operated with 1800 ERP and a two bay H and got permission to go circular 1300 ERP. The antenna arrived on a Friday afternoon and we installed it immediately. Our morning DJ had already left before the antenna arrived. As he returned Saturday his girl friend tuned in the station 20 miles out and informed him the new circular antenna was in and working to which he laughed her off until he arrived at the station. As a youngster all fms were H and fluttered on car radios once you got 7 to 8 miles away despite erp.
 
For all my FMs in Ecuador, the first in the country back in 1965 onward, I found vertical only much better in the Andes. Every one of my FMs was vertical only.
 
The H polarization was chosen for FM stations originally because the horizontal plane has less noise. This was in the 40's when much listening was at home and early fm radios had noise issues also the reason for pr-emphasis.
 
Thank you for the feedback. For in-car listening the H-vs-V issue may not be so severe these days. Most cars now have glass-embedded antennae which seem to work with both signal polarities. Trucks and large SUVs with external vertical whips would obviously still experience picketfencing and flutter from H-only transmissions.
 
Unless it's a short spaced or a legacy dual polarized station that wants to pay a large power bill, most upgrades I have seen lately. in filings are circular.

When was the last time a dual polarized antenna been installed for a commercial station?
 
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