Beverage Question

Medium & long wave antenna discussion
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John Faulkner, Skegness
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Beverage Question

Post by John Faulkner, Skegness » 24 Sep 2016 21:37

I've asked this question some time ago and I can't remember the exact answer.

As I understand it, running an antenna wire along an existing wire fence is not a good idea, but I wondered why.

A few years ago, I conducted some listening experiments in rural Derbyshire, using a wire fence 0.9 miles long as an antenna. It was low grade wire, suitable for keeping sheep in fields and no doubt had a lot of resistance along its length, so I never expected it to perform miracles, but I had some good catches.

This wire fence had several lengths of wire running in parallel underneath. The bottom few rows were connected together and would have been grounded. Something similar to this: http://www.tapscottruralfencing.com.au/ ... encing.jpg I would tap into the top wire, which was isolated from ground.

I never actually ran a length of insulated antenna wire along the top wire but I guess there would have been minimal resistance and I could have terminated the far end to ground via a resistor. But what if I did? Would there be severe interaction which would render the whole exercise pointless?

I know this is not the way to run out Beverage antennas, but if I could do it this way without any detrimental interaction with the wire of the fence, then it would open up a lot more potential locations to run out such antennas.

Thanks.

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Julian Hardstone
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Re: Beverage Question

Post by Julian Hardstone » 25 Sep 2016 01:55

It would reduce the resistance and hence loss without affecting anything else, but as a Bev is a high-impedance antenna, reducing the resistance of the top by a few tens or even hundreds of Ohms would have negligible effect on signal levels

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John Faulkner, Skegness
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Re: Beverage Question

Post by John Faulkner, Skegness » 25 Sep 2016 10:47

Thanks Julian.

I know we have discussed this in the past, but my memory is not good these days. This is useful information for the forum too.

I suppose the other effect would be that the wire would effectively become the ground and so the overall effect would be the same as if the wire was laid on the ground. i.e. a BOG. But, since the wire is thinner and maybe less 'apparent' to the antenna wire, perhaps that ground effect is less.

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Julian Hardstone
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Re: Beverage Question

Post by Julian Hardstone » 25 Sep 2016 15:14

Not sure what you're saying about 'the other effect'. I understand you intend to run the copper wire in intimate proximity to the steel wire. They could be connected together at the feed point. Neither should be grounded.

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John Faulkner, Skegness
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Re: Beverage Question

Post by John Faulkner, Skegness » 25 Sep 2016 17:29

I knew I'd have trouble explaining this. :)

I was pointing out that the antenna wire might see the metal fence wire as the physical ground below, making a Beverage act as if it was a Beverage on the ground to some degree.

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