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peter scott
Joined: 18 Dec 2007 Posts: 7126 Location: Edinburgh
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Penman
Joined: 23 Nov 2007 Posts: 4765 Location: Swindon, Wilts.
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Posted: Wed Mar 17, 2021 10:55 am Post subject: |
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Hi
I'm ready to admit to knowing nothing about radio reception, but is there a reason why the metal body of a car can't be an aerial? _________________ Bristols should always come in pairs.
Any 2 from:-
Straight 6
V8 V10 |
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peter scott
Joined: 18 Dec 2007 Posts: 7126 Location: Edinburgh
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Posted: Wed Mar 17, 2021 11:08 am Post subject: |
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You are probably right although you might need to power the set from its own internal battery rather than the car battery. Also, I think tyres nowadays are slightly conductive so you might lose a little signal strength there.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Vulgalour
Joined: 08 May 2018 Posts: 475 Location: Kent
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Posted: Wed Mar 17, 2021 3:03 pm Post subject: |
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Oh, that's a neat solution! I like that a lot. |
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1738 Location: Above the snow line in old Monmouthshire
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Posted: Thu Mar 18, 2021 2:44 am Post subject: |
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Penman wrote: | Hi
I'm ready to admit to knowing nothing about radio reception, but is there a reason why the metal body of a car can't be an aerial? |
I know as little as you, but I reckon if it were possible to use the car body as an aerial then the big manufacturers would have been doing it for years. |
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peter scott
Joined: 18 Dec 2007 Posts: 7126 Location: Edinburgh
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Posted: Thu Mar 18, 2021 10:13 am Post subject: |
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Bitumen Boy wrote: |
I know as little as you, but I reckon if it were possible to use the car body as an aerial then the big manufacturers would have been doing it for years. |
It's not impossible but you need to decouple the aerial signal from the power supply. If the car's bodywork is floating relative to ground then it will pick-up radio signals but if you are powering your car radio from the car battery then the radio won't see the signal because there is no voltage difference between its aerial input and its signal reference which is the car battery. If you power the radio from a separate supply that is not connected to the car's body or battery then it could use the body as an aerial.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Penguin45
Joined: 28 Jul 2014 Posts: 382 Location: Padiham
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Posted: Thu Mar 18, 2021 11:49 am Post subject: |
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I think that in the early days there were aerials which mounted to the chassis under the car?
Chris. _________________ '67 Wolseley MkI 18/85, '70 Austin MkII 1800 The Landcrab Forum. |
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peter scott
Joined: 18 Dec 2007 Posts: 7126 Location: Edinburgh
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1738 Location: Above the snow line in old Monmouthshire
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Posted: Sat Mar 20, 2021 3:44 am Post subject: |
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peter scott wrote: | Bitumen Boy wrote: |
I know as little as you, but I reckon if it were possible to use the car body as an aerial then the big manufacturers would have been doing it for years. |
It's not impossible but you need to decouple the aerial signal from the power supply. If the car's bodywork is floating relative to ground then it will pick-up radio signals but if you are powering your car radio from the car battery then the radio won't see the signal because there is no voltage difference between its aerial input and its signal reference which is the car battery. If you power the radio from a separate supply that is not connected to the car's body or battery then it could use the body as an aerial.
Peter |
That makes sense. I assume, then, it could also work if all the car's electrical equipment were insulated from the body and provided with earth wiring to complete the various circuits? Like has to be done with fibreglass bodies, in other words. Not that I think it would be terribly practical, but the theory is interesting... |
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Peter_L
Joined: 10 Apr 2008 Posts: 2680 Location: New Brunswick. Canada.
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Posted: Sat Mar 20, 2021 1:59 pm Post subject: |
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I am confident of a knowledgeable replies. Why does my GPS and Cellphone work with much less "antenna area" than the in car radio ? I understand that GPS is satellite and normal Cell/Mobile comes from towers. Why can't all come via satellite ? |
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peter scott
Joined: 18 Dec 2007 Posts: 7126 Location: Edinburgh
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Posted: Sat Mar 20, 2021 2:24 pm Post subject: |
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If your car radio is receiving AM or FM then it's using very much lower frequencies than your phone/gps. Lower frequencies mean longer wavelengths and bigger aerials.
You could choose to receive radio signals via a satellite network such as Sky here in the UK. Or you could receive the internet radio broadcasts from just about every radio station in the world on your phone. There are loads of web radio apps.
GPS uses multiple satellites and your receiver searches to find the ones in range. Satellite broadcasters normally only use one geostationary satellite and you need to point your receiving aerial directly at it which is not so useful in a moving vehicle.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Peter_L
Joined: 10 Apr 2008 Posts: 2680 Location: New Brunswick. Canada.
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Posted: Sat Mar 20, 2021 11:03 pm Post subject: |
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Thanks Peter. I was confident that you would have an answer. Was it the very low frequency used by WWII "Chain Home" radar that required such huge masts, or just to "see" further over the curvature ? |
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peter scott
Joined: 18 Dec 2007 Posts: 7126 Location: Edinburgh
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Posted: Sun Mar 21, 2021 12:01 am Post subject: |
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Peter, you're testing my knowledge to the limit. The Chain Home radar used frequencies that were very low when compared with the systems developed later like H2S which was used onboard Lancaster bombers that gave much greater resolution.
The Chain Home system used frequencies in the 20 to 50 MHz range. It was believed that the range was basically line of sight to the horizon so the towers were built tall to extend the visible horizon. H2S and some German radars introduced about the same time operated at about 10GHz.
Peter. _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Vulgalour
Joined: 08 May 2018 Posts: 475 Location: Kent
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Posted: Sun Mar 21, 2021 9:06 pm Post subject: |
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I don't know much about radio, but with every new post from folks here I'm learning a bit more!
It has been a productive day on the Lanchester, plenty of footage for an upcoming Lanchester video. Almost got the interior back together now and decided to plonk the Ekco in the cabin to see just where it might fit and... er...
That's going to require some thinking. One advantage of the tiny interior of the Lanchester is that the orange carpet I saved from the Princess has actually got enough material in it to do the Lanchester, at least on a first trial fit, and the colour is a lot less offensive than you might expect due to the copious amounts of brown.
There will be a full and proper video update and write up in a few weeks when the interior should be all together. As you can see, I did figure out how to get the dashboard in without removing the steering wheel and three out of four door cards are fitted, the fourth requires some fitment fettling and we simply ran out of time today to do any more. These old car interiors are surprisingly labour intensive to put together and so cramped that recording-while-doing is almost not an option. |
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Vulgalour
Joined: 08 May 2018 Posts: 475 Location: Kent
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Posted: Tue Mar 30, 2021 5:00 pm Post subject: |
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Time for a Lanchester video.
https://youtu.be/Ys8eIjhzlks
Getting the interior refitted threw up its own challenges, and we're learning as we go. I'll do the full write up later when the video has had chance to get a bit of attention, that way I can hopefully address any questions etc. when I do the write up. |
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