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Old 28th Oct 2018, 9:58 am   #1
G6Tanuki
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Default Curious VHF antenna. Pager ??

Spotted this rather sad and decayed antenna setup on the roof of Savernake hospital, Marlborough, recently.

Strange things about it:

1] for each of the 2 surviving 'complete' antennas it looks to me like the driven element and the second-element are the same length, rather than the more-usual longer-reflctor or shorter-director.

2] There are three coax feeds, one per antenna.

It looks too small to be an upper-end-of-Band-I TV antenna (and the arrangement wouldn't make sense for that) - I'd guess it's cut more to be Band-II

But what? Were there any pagers using those frequencies?
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Old 28th Oct 2018, 10:37 am   #2
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Default Re: Curious VHF antenna. Pager ??

Hospitals radio, though wired and internal, do get frequencies assigned for radio links between hospitals in an area. so there are all sorts of things it could be. Hospital pagers are unlikely to want directional antennae.

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Old 28th Oct 2018, 10:50 am   #3
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Default Re: Curious VHF antenna. Pager ??

I hadn't thought of hospital radio. There used to be a 'treatment/assessment centre' a couple of miles away which would have been in the direction these antennas would appear to be pointing - it could well be a hospital-radio relay link.
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Old 28th Oct 2018, 12:29 pm   #4
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Default Re: Curious VHF antenna. Pager ??

Link to ambulance control? There were lots of emergency services around 101MHz until the mid 80s.
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Old 28th Oct 2018, 12:41 pm   #5
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Default Re: Curious VHF antenna. Pager ??

My guess is that the element nearer the camera is slightly longer than the further one. They could be a phased array, pointing away from the camera. This would give a wide horizontal beamwidth yet still some useful gain by restricting the vertical beamwidth.
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Old 28th Oct 2018, 1:20 pm   #6
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Default Re: Curious VHF antenna. Pager ??

FM Broadcast RX for R2,R3 and R4 is my guess.

One Ant>One RX>Wired distribution system for headphones over the beds.
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Old 28th Oct 2018, 1:36 pm   #7
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Default Re: Curious VHF antenna. Pager ??

Would three antennas plus installation be cheaper than one antenna plus a splitter?
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Old 28th Oct 2018, 5:41 pm   #8
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Default Re: Curious VHF antenna. Pager ??

About 25 years ago there was a infrequent burst of data transmission on about 110.5 Mhz from a similar, but only two arrays, set-up, located at our local hospital less than a mile from my house. (So strong, I DF'ed it out of curiosity). The arrays pointed out into open country, so I dont know who the intended recipient was. Long gone now, but it appears from my little investigation that that part of the spectrum was used for data transmissions at that time.. Tony
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Old 28th Oct 2018, 8:18 pm   #9
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Default Re: Curious VHF antenna. Pager ??

Some fascinating suggestions!

I wonder if the 110.5MHz data-bursts could have been an 'uplink' to a wide-area-pager network operating from a rather better-positioned transmitter?
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Old 28th Oct 2018, 9:24 pm   #10
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Default Re: Curious VHF antenna. Pager ??

The early pager at the BRI in Bristol used approx 27MHz. The coverage was maintained by using a lot of vertical dipoles throughout the hospital, even some underground in the tunnels, that way there was no where where there was no signal. The shown aerials are 'directional' so full coverage of the site might be difficult.
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Old 1st Nov 2018, 11:32 pm   #11
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Default Re: Curious VHF antenna. Pager ??

Are the aerials directed at a BBC broadcast site? I suspect that these are part of a broadcast reception system, for Radio 2, 3, 4 or whatever. Most pager systems would use vertical polarisation I reckon. They don't look like link aerials either. VHF links were typically 150MHz upwards, and more commonly UHF or microwave. I would also expect a link aerial to be 3 elements or more.
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Old 2nd Nov 2018, 7:02 pm   #12
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Default Re: Curious VHF antenna. Pager ??

Quote:
Originally Posted by Biggles View Post
Are the aerials directed at a BBC broadcast site? I suspect that these are part of a broadcast reception system, for Radio 2, 3, 4 or whatever. Most pager systems would use vertical polarisation I reckon. They don't look like link aerials either. VHF links were typically 150MHz upwards, and more commonly UHF or microwave. I would also expect a link aerial to be 3 elements or more.
Alan.
They're not obviously pointed at any BBC site: if they were for FM broadcast I'd have expected them to point to the Marlborough transmitter, which is only about half a mile away!

I don't think they're for pagers - as you say they usually used vertically-polarised antennas. OTOH they *could* be link antennas pointing at a pager relay-transmitter covering a wider area than just the hospital; the medics I knew who had pagers in the 70s and 80s had no problems with them working when 20-odd miles from the hospital (much to their annoyance when they were woken at stupid-hundred-hours even though they weren';t on-call that night!).
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Old 2nd Nov 2018, 7:22 pm   #13
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Default Re: Curious VHF antenna. Pager ??

I think there was an Community alarm system frequency 107.9875MHz used before
FM broadcasts were expanded - I actually saw a Pye M294 crystalled for this channel.
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Old 2nd Nov 2018, 9:09 pm   #14
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Default Re: Curious VHF antenna. Pager ??

Re;pagers going off, I used to be involved with maintaining Fire call alerters and regularly used to hear some poor out of breath fireman crash through the station doors just after running up the pager system into a test set. If they happened to work just over the wall from the station there was sometimes enough leakage to set the pager off. We always used to send a special test code to give a different call sound but they still used to come running. After seeing the yellow van parked outside there was often much swearing, (usually directed at us).
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Old 4th Nov 2018, 1:27 am   #15
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Default Re: Curious VHF antenna. Pager ??

Quote:
Originally Posted by Restoration73 View Post
I think there was an Community alarm system frequency 107.9875MHz used before
FM broadcasts were expanded - I actually saw a Pye M294 crystalled for this channel.
Indeed you did, I worked for one of the companies which supplied and maintained one of those 'M' band networks. When we got kicked off there the system moved to several simplex frequencies around 160MHz, still using Pye M294s.
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