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Old 21st Aug 2016, 12:10 pm   #1
G6Tanuki
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Default "Delta dipole" Band-II FM receive antenna.

Locally, there are a number of these interestingly-styled broadcast-FM receive antennas. I guess they date from the early/mid-1960s when FM first appeared here in the UK.

The elegantly-but-non-traditionally-shaped folded dipole *must* be a cosmetic/sales-feature as I can see no possible way this can actually improve gain or directivity!
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Old 21st Aug 2016, 5:28 pm   #2
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Default Re: "Delta dipole" Band-II FM receive antenna.

Never seen one like that before. Usually it's just a folded dipole driven element. Possibly designed like that for more strength, or just a sales gimmick to make their brand of aerials stand out from the norm.
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Old 21st Aug 2016, 5:36 pm   #3
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Default Re: "Delta dipole" Band-II FM receive antenna.

I've never seen one either. They must be local to your part of the world.
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Old 21st Aug 2016, 6:08 pm   #4
G6Tanuki
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Default Re: "Delta dipole" Band-II FM receive antenna.

The one photographed is in Woolhampton (between Reading and Newbury) and is visible from the A4 Bath Road.

There are several more of the same type visible along the A4 between Newbury and Thatcham. I guess there was an aerials-company in the area whose salesmen pushed this particular design hard in the 1960s.
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Old 21st Aug 2016, 6:35 pm   #5
Andrew B
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Default Re: "Delta dipole" Band-II FM receive antenna.

The slope on the dipole is to take advantage of the new variable slope valves in the radio??
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Old 21st Aug 2016, 6:39 pm   #6
G6Tanuki
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Default Re: "Delta dipole" Band-II FM receive antenna.

*grin* I think it was more inspired by 1960s "Delta-wing" aircraft. Who wouldn't want something inspired by a Vulcan bomber on their chimney to demonstrate to the locals that they were receiving the new transmissions?
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Old 21st Aug 2016, 8:17 pm   #7
RogerEvans
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Default Re: "Delta dipole" Band-II FM receive antenna.

This is a complete guess - does increasing the spread of the folded dipole have any bandwidth advantage?

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Old 21st Aug 2016, 8:34 pm   #8
G8HQP Dave
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Default Re: "Delta dipole" Band-II FM receive antenna.

Yes, there should be an improvement in bandwidth. As a general rule, the more space an antenna element occupies the wider the bandwidth. Having said that, it is still possible that marketing was the main aim here.
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Old 21st Aug 2016, 10:21 pm   #9
Hartley118
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Default Re: "Delta dipole" Band-II FM receive antenna.

That looks like a Maxview aerial. Back in 1976 in the Cambridge area, our local aerial contractors fitted them as standard. Maxview is a Kings Lynn company - still going - that nowadays makes a feature of aerials for caravans, boats etc.
http://www.maxview.co.uk/support-and-information

Ours seemed to work pretty well in those primitive days when the only stereo FM available in Cambridge was all the way from Wrotham. Fortunately, signal distribution has improved since then!

I always wondered whether there was any theoretical basis for that 'delta' dipole element. I decided it was probably just a more robust folded dipole designed to withstand the fenland winds!

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