EMI TV end fed wire antenna.

[peter_scott]

What would the AP transmitter mast have looked like for horizontal polarisation?

Peter

[Panrock]

Maybe like the array at the top of the Empire State Building ?

Steve

[Panrock]

And what polarisation was the Eiffel Tower transmitter used by the Germans during the war?

Steve

[G6Tanuki]

Originally Posted by peter_scott

What would the AP transmitter mast have looked like for horizontal polarisation?

Peter

A bunch of stacked multi-wavelength-long 'extended haloes?' Or Batwings or Turnstiles - as were used in the US for the first FM/TV broadcasts?

https://en.wikipedia.org/wiki/Turnstile_antenna


https://en.wikipedia.org/wiki/Batwing_antenna


Or Big horizontally-polarised loops made out of fat copper pipe, with hundreds of Amps of RF flowing....

In times-past when I needed an omnidirectional horizontally-polarised antenna working on 86MHz for a professional application I used a 'cloverleaf' - see https://vk6ysf.com/146mhz_cloverleaf_antenna.htm


What did the Wrotham mast look like for the first FM broadcasts [which were horizontally-polarised].

[Panrock]

Originally Posted by G6Tanuki

What did the Wrotham mast look like for the first FM broadcasts [which were horizontally-polarised].

"cylindrical slot aerials producing the horizontally polarised signals"... see http://txfeatures.mb21.co.uk/wrotham/history.php

Steve

[peter_scott]

I'm not sure that slot aerials had been devised in 1936.

How did the gain of the horizontal arrays compare with the H aerials at AP?

Peter

[emeritus]

Here's the PDFs of the article describing the Ally Pally TX aerial. The introduction states that vertical polarisation had been found inbearlier experiments to yield a greater field strength at ground level.

[Radio Wrangler]

The Alford Slot antenna seems to have appeared in 1946. Andrew Alford graduated in 1924 and was responsible for VOR and ILS antenna designs which have their origins in early WWII, or just prior.

Slot antennae might have been worked on in 1936, but I don't think they'd have been in commercial use.

David

[marceljack]

Originally Posted by Panrock

And what polarisation was the Eiffel Tower transmitter used by the Germans during the war?

Steve

The 441 lines Eiffel Tower transmitter (42 / 46 MHz) was vertically polarised before the war (455 lines, 1938 /39), during the war (441 lines, 1943 / 44) and after the war (441 lines, 1946 -1956).

[Andy Green]

Originally Posted by G6Tanuki

Fascinating... must admit, my experience on 50, 70 and 144MHz has been that horizontally-polarised signals give better distance-covering ability. Vertical polarisation makes sense for mobile [handheld walkie-talkie and whip-antenna-on-a-vehicle, working to a vertically-polarised repeater or base-station] - if only because omnidirectional horizontally-polarised antennas are practically difficult to engineer for handheld or vehicle applications.

Horizontal polarisation was used for UK Band-II FM broadcasting.... though from the 1870s there was a move towards slant polarisation so mobile/portable reception was better.

I’d say what happened is that channel 1 is only barely VHF, and even the top end of the HF band gives better ground wave coverage with vertical rather than horizontal, but you are right, VHF does work better (provided both aerials are the same polarisation) with horizontal pol.

[Hybrid tellies]

I have heard both sides of the argument about polarisation. I have heard that vertical gives better ground level coverage at all frequencies but is more prone to electrical interference especially at the lower frequencies such as VHF Bands 1 and 2. Horizontal polarisation is more immune to most types of electrical interference and that was why it was chosen for the original VHF/FM radio network but does suffer more from aircraft flutter or reflections than vertical polarised signals. Both vertical and horizontal polarisation was used for the 405 VHF TV networks to reduce co channel affects between transmitters which enabled both the BBC and ITA to provide TV coverage for much of the country using just five channels in VHF band 1 and seven channels in VHF band 3.

Going back to 405 line reception where I lived in west Cornwall most of the village received BBC1 on ch2 from North Hessary Tor which used vertical polarisation. It obviously covered the ground well as we were some 60 miles distance from the North Hessary Tor transmitter most people only requiring a loft or H/X rooftop aerial.

Reception was rarely disturbed by the helicopters flying in and out of the nearby RNAS Culdrose base. Whereas people living in the higher parts of the village received BBC 1 on ch1 from Redruth, about 24 miles distance using horizontal polarisation. Reception was good but suffered dramatic aircraft flutter interference from the helicopters. This was not helped by mean level AGC which was used by most 405 and dual standard 405/625 black and white televisions of this era.

Also interesting to note that Redruth used a very large elaborate band 1 slot aerial array to get the required coverage and avoid causing co channel interference for viewers in other parts of the UK that also used ch1. Most medium to high powered VHF band 1 transmitters used simpler and smaller vertical or horizontal dipole systems.