Antenna review, ? on broadcast polarization.

[delta_charlie]

Hi all, long story short I had an UHF only TV antenna up and it worked great on all channels but one. I would get picture breakup on CH 2.1 and about 2 weeks ago it was so bad I got motivated to figure out why. Turns out CH 2.1 is on VHF high band and not UHF. Well that explains that. Ordered a replacement dual band UHF/VHF Channel Master 2016 and it is working great. Looks to be well made and I loved the unfold and snap into position of the elements. It works just as good as the UHF antenna I had up before on UHF and I picked up 14 much needed points on the VHF channel.

This morning I went for a nice bike ride out to the broadcast tower and it sure looks like to me the tower has vertical elements. Why are all TV receiving antennas mounted horizontal? At least I have not seen any. Anybody know for sure what polarization broadcast TV uses?

Thanks, DC

 

[Stargazer]

Most markets use horizontal polarization. Most man made interference is found on vertical polarization. Some stations use circular polarization which has a loss of 3 db if you use a vertical/horizontal and not a circular polarized antenna compared to having a 20 db loss by having your antenna polarized incorrectly.

 

[lfp302]

Wow, that's fascinating. I never knew OTA was like that.

 

[mike123abc]

How do you tell by looking at the TV tower which polarization it is using?

 

[delta_charlie]

How do you tell by looking at the TV tower which polarization it is using?

All I could see on the top of the tower was vertical elements, they should only produce vertical polarization; however, after doing some google searches my understanding now is the elements are not what they appear. One item I read said they have slots in them that send out horizontal polarization in select directions with a little gain. I found it very interesting.

 

[Stargazer]

Reflections such as mountains and buildings can change the polarization of the signal. In the past, seeing the sector antenna in a way as shown on the tower earlier in this thread would indicate a vertically polarized antenna but there are new technologies that allow them to switch polarizations in the antenna at least the ones that the wifi wisp providers use. The lower the frequency the larger the antenna needs to be.

 

[Trip]

The FCC requires all TV stations to transmit either horizontal-only, or horizontal with some amount of vertical that is less than or equal to the horizontal. TV stations cannot be vertical-only in the US, though countries like Australia do have vertical-only stations.

- Trip

 

[Stargazer]

Reflections such as mountains and buildings can change the polarization of the signal. In the past, seeing the sector antenna in a way as shown on the tower earlier in this thread would indicate a vertically polarized antenna but there are new technologies that allow them to switch polarizations in the antenna at least the ones that the wifi wisp providers use. The lower the frequency the larger the antenna needs to be.

I stated vertically polarized when it should have stated horizontally polarized. The antennas are longer vertical but are actually horizontal polarity.

 

[Satftafan]

Most markets use horizontal polarization. Most man made interference is found on vertical polarization. Some stations use circular polarization which has a loss of 3 db if you use a vertical/horizontal and not a circular polarized antenna compared to having a 20 db loss by having your antenna polarized incorrectly.

Great info