Vertical V horizontal polarisation..

[colly0410]

Been reading 'American Radio History.com' site where they say in the 1940's that horizontal polarisation is better than vertical for 50-100mhz, at higher frequencies there was no measurable difference, & of course the USA used horizontal polarisation for all TV transmissions. So why did the UK stick with with vertical polarisation for it's high power band 1 stations after 1949? I can understand Crystal Palace using VP as there would be legacy aerials on rooftops for Alexadria Palace & viewers would not be happy if the had to adjust/buy new aerials for HP. But Sutton Coldfield, Holme Moss, Kirk-O-Shotts & Wenvoe were clean starts & could have used HP with no problems as no legacy aerials to worry about. Perhaps second tier medium power TX's such as Divis, Pontop Pike, etc could have used VP for co-channel reduction. Funny how they used HP for VHF/FM till recently which is on the borderline of making no difference..

[Mike Watterson]

Horizontal is better for longer distance / fringe coverage over the horizon, at higher frequencies the over the (optical) horizon shortens and thus horizontal is less important.
Vertical (or circular) is better for mobile.
Circular has a half power penalty unless you have circular reception of the same handedness, (1/4 distance at same power) but works equally with horizontal or vertical polarised aerials.

Still, today, long distance SSB or digital mode Amateur radio with larger aerials is always horizontal, 144 MHz, 430MHz and 1.2GHz bands. Higher bands tend to use dishes and might use both polarisations (on separate channels) for full duplex). Amateur Satellite, C band and Ka band often is Circular polarisation (in some cases because satellite is rotating, or weather rotates the signal. Most Ku band satellite uses horizontal and vertical on alternate channels, which thus can overlap slightly. Same may be true on Ka, except the handedness of circular is reversed.

Mobile Amateur is always vertical.

I've no idea why the useless negative gain halo aerials are still sold for Band II FM as no Band II has been horizontal only for years.

On Band III and UHF, Horizontal and Vertical is used on TV (still) to provide extra isolation on co-channels. Due to greed, European regulators, cheered on by FCC and Ofcom are taking away 700MHz to Mobile.
It dooms TV to having no space for fill in for Mobile use, 3D or 4K services or innovation. But Ofcom and Comreg already stated they want to abolish Terrestrial TV altogether.
700 and to a lesser extent 800 are too low a frequency for decent mobile capacity as cell size is poorly controlled and too large.
The latest 4G spec (and regulators) allow the Mobile companies to use 4G channnels in pure broadcast mode to deliver Pay TV. Internet TV (esp. Mobile) isn't scaleable. Cable and Satellite are complementary to Terrestrial, not a replacement, but then Regulators are only interested in subscription / pay services as they can charge more for spectrum licences.

You see why 700 & 800 is being sold to Mobile? Not for better Mobile. But to save costs and make government revenue. New coverage claims for so called 5G say nothing much about performance. More smaller cells costs more but gives more speed and lower power at mast, and lower power (x4 battery life) in handset.
The 900, 1800, 2100 are underutilized. The 2500 will be underutilised too.

It's greed and madness.
So is so called "White Space".

[Murphyv310]

Hi.
I wonder what is meant by "better" being horizontal? Could it be interference effects, range, or what.
Many moons ago I used to take a Philips T-Vette in my Skoda 1000MB on my travels and I could receive Channel 3 from Kirk 'O Shotts in conditions that were far from ideal and at distances way out of the service area. Whether I'd get any noticeable change if the transmission was on the opposite polarisation is debatable, vertical seemed to work well on Band 1 though.

[colly0410]

Hi.
I wonder what is meant by "better" being horizontal? Could it be interference effects, range, or what.
.

Think it was a combination of those, it said "less car ignition interference with horizontal!" & "better fringe reception!" It did say that lower that 1 wavelength (about 25 feet on channel 1) or so vertical was better, but when aerial was higher HP became better. 

 Suppose VP was good for those using set top aerials on the ground floor of houses. When you watch old TV programs like 'Alf Garnett' & 'On The Buses' they're always watching a TV with a  stereotypical V shaped rabbit ears aerial stuck on top of it, often moving it around to try & get a better picture for comedy effect...

[Terry]

So why did the UK stick with with vertical polarisation for it's high power band 1 stations after 1949? I can understand Crystal Palace using VP as there would be legacy aerials on rooftops for Alexadria Palace & viewers would not be happy if the had to adjust/buy new aerials for HP. But Sutton Coldfield, Holme Moss, Kirk-O-Shotts & Wenvoe were clean starts & could have used HP with no problems as no legacy aerials to worry about. 

Having started off with VP for the first main station - AP/CP - perhaps it made logical sense to continue this for other main stations?

This permitted the additional protection between transmitters of differing polarisation to be fully exploited, although not all HP stations were low power - Sandale and Tacolneston were reasonably powerful. 

ITA practice was to broadly follow the polarisation of the BBC transmitter but here there were quite a few sites that packed an HP punch - Black Mountain, Burnhope, Caldbeck, Durris, Mendlesham & Presely, for example. Band I listings can be found here: scroll down for ITA allocations.

[Murphyv310]

Hi.
The interesting one was STV from Black Hill on Ch10. When the original aerial array was mounted it was found to have horizontal polarization, this is odd as it seems it wasn't properly worked out. it was a couple of years later before it was rectified and changed to vertical, I believe it was 59 or 60. One old colleague told me he used to do the old blocks of houses going along the roofs and turned hundreds of aerials for 10 bob a go.
Reception vastly improved after the change over which I remember well.

[Terry]

One old colleague told me he used to do the old blocks of houses going along the roofs and turned hundreds of aerials for 10 bob a go.

Trevor, you make it sound as if he just worked his way along the roofline of terraced blocks, rather than going up and down to each one. If so, the time saving would indeed have made this 'a nice little earner'!

Given the value of ten bob in those days - more than 6½ pints at, say, 1/6 a pint - that would be a tidy sum! (Best not to start drinking the profits until the job was done, though!)  

[Synchrodyne]

The NTSC’s reasons for choosing horizontal polarization were provided in Fink, “Television Standards and Practice”; see chapter X.  (See:  https://archive.org/stream/televisionsta...h_djvu.txt; and:  http://www.earlytelevision.org/pdf/telev...ndards.pdf.)  This quotation from early in the chapter provides a succinct summary:  “By the time the Panel concluded its deliberations, however, sufficient evidence had been assembled to bring about substantial agreement that there was a slight preponderance of advantage for the horizontal direction.”

It would appear that outside of the UK, the NTSC’s precedent was followed, with the addition that in some territories, vertical polarization was also used, typically for secondary transmitters, in situations where the use of orthogonal polarization would ease the problems of channel-sharing.  Thus one might say that although horizontal was preferred, vertical was nonetheless acceptable in certain circumstances.

I haven’t seen anything to suggest that the polarization issue was reviewed in the UK when the TV network expansion plans were drawn up.  So the continued use of vertical polarization for the main transmitters may simply have been inertial.  The BBC’s development work on FM broadcasting had shown horizontal to be better than vertical, particularly in respect of ignition interference rejection.  But that does not seems to have influenced the TV case.  Or perhaps it was the GPO, who had the final sign-off on transmitter frequencies, power, etc., who made the polarization call.  (Later on it was the GPO who dictated that the polarization of ITA TV stations would match those of the respective BBC stations in each area.)  The Sutton Coldfield mast was built with horizontally-polarized Band II radiators for future FM use, so the BBC had made its determination by then.  Presumably the mast could have been topped with a turnstile stack had horizontal polarization been chosen for the TV transmitter.

The NTSC had also determined that the same polarization should be used for both TV and FM transmissions.  Presumably this was the convenience of consumers, who could then use combined receiving aerials.  Whether that aspect was considered in the UK is also unknown.


Cheers,

Steve

[colly0410]

Heard tales about some people who couldn't afford a TV put an H or X aerial on the chimney to make it look like they do have one to impress the neighbours. VP aerials would stand out & be noticed, HP ones not so much. Suppose when the HP TX's fired up most people could afford a TV anyway so no need to pretend. I was born in 1953 & we always had a TV..

Which TX was the first to use HP?

[Terry]

Unlikely to have been the first but the first one I ever encountered at the age of 11 in 1955 was Tacolneston.

On the Norfolk/Suffolk border where we were camping there were a lot of bungalows with three element HP yagis.

Possibly because of the low height of bungalow roofs, with gravity dragging down the extremities of the elements combined with a gentle waving in the breeze, I have an abiding memory of enormous low-flying stick insects swooping over the roof tops ...