The earliest television aerials

[Panrock]

Mods, please excuse me and move this if I've got the wrong section.

The 'H' and 'X' aerials I grew up with always were all-metal affairs, with the beam section made of metal tubing as well as the elements.

But how far back were television aerials like this? What did the very earliest television receiving aerials look like? For example did they have wooden beams? Was the reflector spacing more generous in the early days?

I seem to remember some sort of long sloping wire in a pre-war copy of Wireless World. When did 'modern' aerial rigging clamps and bits and pieces etc. come into regular use? What did your average pre-war aerial look like... when it was the only one in your street?

Steve

[peter_scott]

Hi Steve,

I suspect this is not quite early enough but here are a few pointers for intermediate history.
My parents had a folded "X" aerial which was screwed to the top of a 2" diameter wooden pole
As I recall it, it was attached to the chimney stack by a corner bracket which had two steel
"L" sections protruding and two "U" bolts clamped the the mast to the "L" sections. The corner bracket
was lashed to the stack with steel braided cable. This dated from 1952 I think.

Peter.

Pictures from books are from 1949, 1950, 1949, 1949 and 1942 respectively.

[Aerodyne]

In his 1941 dictionary of radio and television terms, Ralph stranger describes an 'H' aerial as a half-wave vertical dipole with an added reflector situated a quarter-wavelength from it. I'd guess from this that the dipole and the 'H' were between them the basis for TV aerials in the early years prior to WWII. His only comment on materials is that the elements would be large-diameter copper wire or alternatively copper tube, the assembly mounted on a T-shaped mast and cross-support of indeterminate insulating material, possibly wood!
-Tony

[peter_scott]

Here's a text from 1937..

[Ray Cooper]

To answer the final question...

What did your average pre-war aerial look like... when it was the only one in your street?

This is an interesting study. What we need are a few pre-war advertisements for commercial aerials...


But thinking round the problem a little, my personal mental scenario of what went on goes something like this:-

Realistically, the average pre-war item was probably a straight dipole: the great bulk of viewers would have been in the primary service area. Metal tubing construction, bakelite for the insulators (quite good enough at these frequencies). Probably, nothing more exotic than a straight 'H' (dipole plus reflector) would have been available commercially. Bearing in mind the relatively tiny number of viewers even in 1939 (tens of thousands), the number of viewers in the 'fringe' areas would have been in handfuls, and commercial production of fringe models would not be viable. Since most 'fringers' would have been enthusiasts, home-construction of aerials would not have been considered a challenge, and I expect that wood figured largely here for crossbeams etc. Though, possibly not for support poles, unless well stayed - these Channel 1 aerials were enormous - elements in excess of ten feet long - and the weight and windage of them might have rendered wood supports a little hazardous.

The 'tilted wire' aerial - in effect, a vertical half-rhombic - could give very good results IF you had enough real-estate to erect one, and IF you could point it in the right direction. Those conditions satisfied, they could be a good candidate for home-construction. Another (post-war) interesting wheeze I've seen is for a loft-mounted slot aerial made out of wood battening and chicken-netting...

A subsidiary question, just as interesting in my view, is 'what did they do for feeder-cable to connect the aerial to the set?'. I've come across references to standard twisted mains-cable being used in this application - could easily have been lossy enough to lose any performance that a decent aerial might have given you. Co-ax doesn't seem to have been used at all pre-war: in fact, the first process for the economic commercial manufacture of polyethylene only became available in 1939, so before that time, for a co-ax you'd have to use something like one of the old glass-bead spacer systems to keep your inner concentric: hardly suitable for a domestic installation.

As an aside - a pre-war book I have (Dowding, 1935) suggests that if you use twin-twisted flex for your feeder, 'for optimum results, their lengths should be arranged in odd multiples of quarter wavelength'... since I don't suppose that anybody in those days had the faintest idea of what the velocity factor of twin-twisted flex was, I don't suppose that they therefore knew how long the feeder should physically be. Sounds to me like most of these early aerial systems were grossly mismatched, and decent results were a bit of a lottery.

[ppppenguin]

Originally Posted by Ray Cooper

A subsidiary question, just as interesting in my view, is 'what did they do for feeder-cable to connect the aerial to the set?'. ..[snip].... Co-ax doesn't seem to have been used at all pre-war: in fact, the first process for the economic commercial manufacture of polyethylene only became available in 1939, so before that time, for a co-ax you'd have to use something like one of the old glass-bead spacer systems to keep your inner concentric: hardly suitable for a domestic installation.

Early EMI receivers had a co-ax aerial lead with a monstrous plug on the end. I haven't delved inside the cable but I suspect the insulation is rubber.

[Panrock]

Originally Posted by ppppenguin

Early EMI receivers had a co-ax aerial lead with a monstrous plug on the end. I haven't delved inside the cable but I suspect the insulation is rubber.

Here's a quick snap of the two ends of the aerial coax lead from my '37 Marconi 702.

Note the paint on the plug (wainscoting decorating perhaps?). What are these plugs called? I seem to remember someone said they were also used by the GPO.

The internal insulation includes a rubber and fabric sheath, with some sort of crumbly material directly around the inner conductor.

Steve

[Ray Cooper]

Panrock:

The internal insulation includes a rubber and fabric sheath, with some sort of crumbly material directly around the inner conductor.

That's very interesting. Could the crumbly material be rotted foam-rubber, perhaps? An early attempt at a foam-filled interior?

Not even all of the receivers produced after the war used co-axial inputs - our first Ferguson (1950) used balanced twinline feeder, terminated by a horrible 'battery-style' two-pin plug (fine sets, these Fergusons).

[Panrock]

Originally Posted by Ray Cooper

That's very interesting. Could the crumbly material be rotted foam-rubber, perhaps? An early attempt at a foam-filled interior?

Could well be. Any idea what the loss figure at 45Mc/s for this sort of cable would have been ?

Steve

[peter_scott]

Albert's aerials http://www.wrightsaerials.tv/albertssecondaerial.htm does show a pre-war aerial sketch and it appears again here with a clearer illustration:

http://www.dennysantennaservice.com/1342175.html

[Panrock]

Thanks Peter. It certainly looks like a lossy affair in that second illustration at http://www.dennysantennaservice.com/1342175.html with a long feeder running to the simple dipole down the garden. The aerial itself looks like it's of special construction - not a simple 'tubular' product that we knew.

Steve

[paulsherwin]

I think H and X aerials were almost universal once TV restarted after the war. They were really all you needed, especially at the LF end of band I, and not much more difficult to make than a standard dipole.

I don't remember seeing anything more complex for band I reception until the end of 405, even here in Oxford which was outer fringe from Alexandra Palace at one stage.

The only exceptions were the enormous band I arrays on the Irish coast north and south of Dublin pointing at Holme Moss which were common until the mid 80s, massive structures with lattice masts and guy wires. They've all gone now.

Paul

[Steve_McVoy]

The picture of the 1936 Antenna on Denny's Antenna sight was from our site originally:

http://www.earlytelevision.org/antennas.html

There is a link to an article in Television and Shortwave World below the picture.

There are also some more American and British prewar antennas shown.

[Panrock]

Steve McVoy's page is most interesting. I see that in 1940, a Telcon coax cable had an attenuation of 3dB per 100ft at 44Mc/s. I wonder how that compares with popular cables from the '50s and '60s - and today's cables.

Steve

[Heatercathodeshort]

Hello,
When I first saw my HMV 900 in the mid 70's it was still connected to the aerial outlet box and the original EMI diople mounted high up on the rear wall of the house. I managed to salvage the co-ax plug and box that is identical to Steve's [Panrock]. Unfortunately the dipole was out of reach and went with the house refurbishment. The cable was thick rubber with a layer of canvas between the screening and the thinner rubber insulation of the inner wire. Pity I didn't cut a length off but it was a long time ago.
As far as I can remember it was a standard dipole with a smaller box section in the middle. Pre war Belling Lee aerials were steel and they recommended that you took it down once a year and gave it a coat of 'good quality paint'..Regards, John.

[Mike Phelan]

When I were nobbut a lad (ca 1953 or so) our next-door neighbour at number 33 had a TV aerial that looked like a bed spring, but a barrel shape.

I am sure that it was there earlier - they got a TV24 (I think) for the Coronation, and I was allowed to watch my first TV.

I am surprised that it actually worked - could it have been an old radio aerial, home-made or an old TV aerial?

Most of the local Band I aerials were just X or H, so reception must have been OK - Ch 5 Wenvoe, IIRC.
Number 33 got a 4-element Band III plus a H for Band I in the later fifties.

[arjoll]

I read through an "Encyclopaedia of Radio & Television" my father has when I first started toying with the idea of fixing his old Ferrograph a few years ago. It mentioned a single vertical dipole as a receive aerial (at least that's the way it was drawn - was the original 45MHz service vertical?).

The encyclopaedia was British in origin, and I think 40's or so, I might have to pop up to dad's this weekend and have a look.

NZ was relatively late to the TV game (1960) and everything I've ever seen here was either a folded dipole or yagi (usually 3 element, maybe 5 element in the fringes). Ribbon was commonplace until the mid 80's, and believe it or not still available!

[paulsherwin]

Originally Posted by arjoll

Ribbon was commonplace until the mid 80's, and believe it or not still available!

Britain seems to have been alone in switching to universal 75 ohm coax downleads as soon as they became economically available, first for TV and then for VHF radio. 300 ohm balanced feeder was still in common use in most of the rest of the world right into the 1990s. In the 1980s it was quite normal to find imported Japanese FM tuners without a coax input thus needing an external balun.

Paul

[ppppenguin]

Originally Posted by paulsherwin

Britain seems to have been alone in switching to universal 75 ohm coax downleads as soon as they became economically available, first for TV and then for VHF radio. ....

Helped, no doubt, by the Belling & Lee co-ax connectors which I'm guessing were invented in about 1950. These are universal in the UK but perhaps less common elsewhere. Now the F connector seems to be gaining ground in the UK too.

[brianc]

Hi All
I have found an advert for Belling-Lee coaxial connectors in the January 1947 Wireless World where they are described as "new". The picture attached shows how little the construction has changed in 60 years - they must have got it right first time! In March of the same year, they describe the Type L503 dipole & reflector aerial for TV.
Cheers
Brian