British weird shaped low band vertically polarized TV antennas..

[Colly0410]

Britain had a thing for weird shaped low band (band 1) TV antennas. Up till about 1952/53 all the main high power transmitters used vertical polarization (rods vertical) & there were H, X & K shaped antennas to be seen on nearly every house roof. When they started firing up medium & low power transmitters in the mid 1950's most of them used horizontal polarization to reduce co-channel interference from the vertical polarization high power TX's. AFAIK vertical polarization was never used for TV in America, why Britain chose it for it's high power TX's I don't know...

[dtvmcdonald]

There is a specific very long-running thread about just that topic, with more
info than you would ever dare think about. Very interesting and fun to read.

https://www.vintage-radio.net/forum/...=95890&page=31

[kf4rca]

In the States UHF stations that used a pylon type of antenna also transmitted with some vertical polarization, while VHFs used almost exclusively super turnstile antennas which were horizontally polarized.
BUT, transmitted polarization is really not important as the wave undergoes all kinds of rotation in the field.
In the early 80's some stations switched to circular polarization (particularly hi-band VHFs). The benefit was that it would get more signal into valleys and had the benefit of ghost cancellation. The circular polarization would reverse phase off the reflected surface and cancel out at the receiver's antenna.
BUT, even more importantly, was the fact that the FCC would allow you to run more power. So, if you were running 100KW horizontally, you could run 100KW vertically also, if the station could afford the added electric bill.
Technically you had 200KW in the air (not counting antenna gain to make ERP).

[Robert Grant]

Originally Posted by Colly0410

Britain had a thing for weird shaped low band (band 1) TV antennas. Up till about 1952/53 all the main high power transmitters used vertical polarization (rods vertical) & there were H, X & K shaped antennas to be seen on nearly every house roof. When they started firing up medium & low power transmitters in the mid 1950's most of them used horizontal polarization to reduce co-channel interference from the vertical polarization high power TX's. AFAIK vertical polarization was never used for TV in America, why Britain chose it for it's high power TX's I don't know...

My guess: Vertical antennas are naturally omnidirectional. Horizontal polarization requires a more complex design to be omnidirectional.

[Phil]

I really hate to disagree, and take the chance of starting a flame war, but no, not the case. Waves do not magically rotate in propagation. I present as exhibit "A" commercial communications satellites. Transponder 1 and 2, for example, are on the same frequency, but one is vertical the other horizontal polarity. Even after traveling some 24,800 miles from the satellite they arrive in exactly the same polarity they left. There is typically, in the real world, about 20-30 db cross polarization loss. I am a radio engineer so I won't speak to anything specifically involving television frequencies, but the idea they would get into valleys, etc , better doesn't make much sense. Circular polarization is really just a linear plane signal rotating at the carrier frequency. The idea that it would cancel ghosts or eliminate multipath is simply myth. Yes, a circularly polarized signal (which doesn't actually exist) changes the direction of rotation when it reflects off an object is true, but is it going to cancel at the receiver? Probably not. Even if it did, would canceling out the signal (assuming it arrived in the proper phase to do so, which would depend on the length of the propagation path in fractions of wavelengths from the reflection point vs. the direct path, be a good thing? Probably not. If it perfectly cancelled you would receive nothing. A circularly polarized signal is nothing more than a linear polarized signal which rotates at the carrier frequency. Since it is in any given polarity for half the time it is necessary to double the power to produce the same signal from an antenna of any given plane.
As to having twice the watts in the air, again, only true if the receive antenna is circularly polarized and of the same sense, which doesn't exist. For any antenna of single plane polarity, regardless of what it is, the received signal is the same as one radiated from an antenna of matching polarity to the transmit antenna and of the same ERP. That is the point of circular polarization. Regardless of whether the receive antenna is vertical, such as older cars, 45 degrees as most newer cars, horizontal or anything random in between the received signal will be the same.
All FM and TV stations are licensed for a particular ERP so the last statement is just irrelevant.

[dieseljeep]

Originally Posted by dtvmcdonald

There is a specific very long-running thread about just that topic, with more
info than you would ever dare think about. Very interesting and fun to read.

https://www.vintage-radio.net/forum/...=95890&page=31

I spent a considerable amount of time looking at that thread. The antennas look really strange to me, but I spend as much time looking at the architecture of the buildings. And those chimneys, real works of art!
Very little like that in this country!
Dave, AKA as US radcoll1.

[Colly0410]

When I was a kid my cousin came to visit from Canada & was fascinated with the vertically polarised H, X & K shaped TV antennas on the roofs of English houses, I asked him if Canadian houses had them? He said "no, everyone in Ottawa has a V shaped rabbit ears antenna on top of their TV!" Must have had a strong signal in Ottawa...

There were some British situation comedy shows where they had indoor antennas on top of the TV. They'd often be adjusting them to try & get a better picture for comedic effect, they'd be saying "left a bit, right a bit, up a bit, down a bit!" & end up losing their tempers, lol.... I've never lived in a strong enough signal area to use an indoor antenna. At my present house I have a UHF antenna that I put up myself in the loft that works OK, I'm too cowardly to put it on the roof...

[kf4rca]

Faraday effect:
https://en.wikipedia.org/wiki/Faraday_effect
Scroll down to In The Ionosphere.
The effect diminishes at microwave frequencies and above.