Odd log periodic TV aerial. - UK Vintage Radio Repair and Restoration Discussion Forum

Tractorfan · 22nd Jan 2017, 11:56 am

Hi,
On a recent trip back to the UK I spotted this UHF log periodic aerial on the side of a house in the Grappenhall area of Warrington. It's pointing towards Winter Hill and appears to be the only aerial on that particular house (apart from the ubiquitous satellite dish), and looks fairly recent. The other aerials in the road are the usual yagis including the immediate neighbours.
I'm just curious if there was any particular reason as to why this type was chosen. (Ghosting, multipath, signal strength, or other problems?)
Cheers, Pete.

Skywave · 22nd Jan 2017, 12:24 pm

As we all know, the usual reasons for installing a log periodic Yagi is to obtain a wide frequency bandwidth - and that implies that suitable equipment is available to use with it - which may well be the case here. So that suggests its user / owner is a VHF / UHF shortwave enthusiast: possibly a licensed radio Amateur who is using it to communicate via a repeater.
OTOH, it might be used only for T.V. reception: something that happened 'to be available' and would have been known to do that job.
But whatever its feeder is connected to, and for what the installation is being used for, the omission of a rotator substantially narrows the possible explanations.

Al.

G6Tanuki · 22nd Jan 2017, 12:31 pm

Don't think it's an amateur-radio antenna; Looks like one of the little Labgear TV ones to me.

LABLPC or LPCT being the Labgear models I'm familiar with. They work quite well in medium-signal areas and are more-discreet than some of the massive 'bling-bling' Yagis (the Televes type with the 3 sets of directors...) which always stick out like a sore thumb.

Nuvistor · 22nd Jan 2017, 12:40 pm

Labgears web page for the LPCT.
http://www.labgear.co.uk/product-cat...dic-tv-aerial/

Frank

Skywave · 22nd Jan 2017, 5:57 pm

Thank you, Frank. It's now quite clear just what that aerial is.

Al.

Lloyd 1985 · 22nd Jan 2017, 8:52 pm

I have a bigger version of that here in my shed, it came off the shed at our old house, worked great in a fairly low down position (on an old metal broom handle!). I might fit it to my new shed, although I have an old loft aerial that I could use.

Regards,
Lloyd

G8HQP Dave · 23rd Jan 2017, 1:53 pm

I put a log-periodic TV antenna in the loft at my previous house. This was because we were close enough to Sandy Heath to get a strong signal, so not much gain required, and it needed a fairly wideband antenna to get all the channels. SH was one of those transmitters which spread outside its original analogue channel grouping quite early in the digital switchover process. Log-periodics make good loft antennas because they are not detuned much by nearby objects, unlike a Yagi.

Lloyd 1985 · 23rd Jan 2017, 2:20 pm

That aerial in my last post used to point at Sandy heath too when we lived in Daventry, whilst the house aerial pointed at Waltham. I'm not sure what transmitter we are receiving here in Coningsby, might be Belmont? It's certainly a strong signal, don't even need a proper aerial, I actually got all the freeview channels on my Panasonic TV with a broken coat-hanger dangling out of the aerial socket!

Regards,
Lloyd.

SteveCG · 25th Jan 2017, 4:22 pm

Log Perodic aerials have 'good' sidelobe responses and good impedance match across their usually wide bandwidth. The main downside is the comparative low forward gain.

They are one of the few aerial designs whose gain can be known from its dimensions with anything approaching confidence. So if you wish to compare aerials then a Log P. makes a good reference.

22nd Jan 2017, 11:56 am	#1
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,184	Odd log periodic TV aerial. Hi, On a recent trip back to the UK I spotted this UHF log periodic aerial on the side of a house in the Grappenhall area of Warrington. It's pointing towards Winter Hill and appears to be the only aerial on that particular house (apart from the ubiquitous satellite dish), and looks fairly recent. The other aerials in the road are the usual yagis including the immediate neighbours. I'm just curious if there was any particular reason as to why this type was chosen. (Ghosting, multipath, signal strength, or other problems?) Cheers, Pete. Attached Thumbnails __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..." Last edited by Tractorfan; 22nd Jan 2017 at 12:00 pm. Reason: Nearly forgot to add photos.

22nd Jan 2017, 12:24 pm	#2
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: Odd log periodic TV aerial. As we all know, the usual reasons for installing a log periodic Yagi is to obtain a wide frequency bandwidth - and that implies that suitable equipment is available to use with it - which may well be the case here. So that suggests its user / owner is a VHF / UHF shortwave enthusiast: possibly a licensed radio Amateur who is using it to communicate via a repeater. OTOH, it might be used only for T.V. reception: something that happened 'to be available' and would have been known to do that job. But whatever its feeder is connected to, and for what the installation is being used for, the omission of a rotator substantially narrows the possible explanations. Al.

22nd Jan 2017, 12:31 pm	#3
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,005	Re: Odd log periodic TV aerial. Don't think it's an amateur-radio antenna; Looks like one of the little Labgear TV ones to me. LABLPC or LPCT being the Labgear models I'm familiar with. They work quite well in medium-signal areas and are more-discreet than some of the massive 'bling-bling' Yagis (the Televes type with the 3 sets of directors...) which always stick out like a sore thumb.

22nd Jan 2017, 12:40 pm	#4
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Odd log periodic TV aerial. Labgears web page for the LPCT. http://www.labgear.co.uk/product-cat...dic-tv-aerial/ Frank

22nd Jan 2017, 5:57 pm	#5
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: Odd log periodic TV aerial. Thank you, Frank. It's now quite clear just what that aerial is. Al.

22nd Jan 2017, 8:52 pm	#6
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,820	Re: Odd log periodic TV aerial. I have a bigger version of that here in my shed, it came off the shed at our old house, worked great in a fairly low down position (on an old metal broom handle!). I might fit it to my new shed, although I have an old loft aerial that I could use. Regards, Lloyd Attached Thumbnails

23rd Jan 2017, 1:53 pm	#7
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: Odd log periodic TV aerial. I put a log-periodic TV antenna in the loft at my previous house. This was because we were close enough to Sandy Heath to get a strong signal, so not much gain required, and it needed a fairly wideband antenna to get all the channels. SH was one of those transmitters which spread outside its original analogue channel grouping quite early in the digital switchover process. Log-periodics make good loft antennas because they are not detuned much by nearby objects, unlike a Yagi.

23rd Jan 2017, 2:20 pm	#8
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,820	Re: Odd log periodic TV aerial. That aerial in my last post used to point at Sandy heath too when we lived in Daventry, whilst the house aerial pointed at Waltham. I'm not sure what transmitter we are receiving here in Coningsby, might be Belmont? It's certainly a strong signal, don't even need a proper aerial, I actually got all the freeview channels on my Panasonic TV with a broken coat-hanger dangling out of the aerial socket! Regards, Lloyd.

25th Jan 2017, 4:22 pm	#9
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: Odd log periodic TV aerial. Log Perodic aerials have 'good' sidelobe responses and good impedance match across their usually wide bandwidth. The main downside is the comparative low forward gain. They are one of the few aerial designs whose gain can be known from its dimensions with anything approaching confidence. So if you wish to compare aerials then a Log P. makes a good reference.