Hello Group,
According to the Services Textbook of Radio, the Beverage is one of the few
aerials which works best over ground of poor conductivity. This is because
the wavefront is slowed down near the partially conducting ground and "tips
forward" and develops a horisontal component. The ratio of the horisontal to
vertical components is about 2% over good soil and 8% over poor ground,
giving an angle of tilt between 1 and 4 degrees. As far as I can see it has
very little to do with the height of the wire above ground, much more to do
with the length of the wire.
Any ground radials for other aerial will probably have a bad effect as it
will reduce ground resistance.
It says it makes a very inefficient transmitting aerial.
I made a scale model of a Beverage and tried it at 2m, just as an
experiment. It was about 2.5 metres long, The thin wire was glued to the
side of a wooden batten, and there were earth spikes at each end with the
load resistors. I picked up local repeaters with it, and it was definately
directional, but obviously several S points down on a 1/4 wave. Finding flat
enough bit of ground in the garden was a problem !
I wish I had a sheep field to make a big one in. Hope it works well.
73
Hugh M0WYE
----- Original Message -----
From: "Brenda Hayes" <[email protected]>
To: <[email protected]>
Sent: Friday, September 07, 2007 9:23 AM
Subject: Re: LF: BOG - Beverage on the Ground
At 01:28 a.m. 7/09/2007, you wrote:
Hi LF gang,
In my sked last night with Finbar (best conditions for some weeks) we
discussed mini-beverage antennas laid directly on the ground. I've done
a Google trawl and there's a bit evidence that they work well.
I have a need to keep things low-profile due to all the adjacent fields
being used for sheep, so running a long (100-200m) wire on the ground is
attractive. I could even run it outside the fenceline along the verge
beside the road - I'm in a very rural area.
Does anyone have any experience of using BOGs on 500kHz?
John
Gm4SLV
Hello John and the LF Group,
A few years ago, Robert, VK7ZAL made regular expeditions to a remote site
near Hobart in Tasmania and listened for our ZL gang who were transmitting
on 181.4 kHz. He ran out a couple of hundred metres or so of insulated
wire, over the ground and bushes, pointed towards ZL, and connected to an
antenna tuner that fed his receiver. I should also add that the far end
was unterminated. Allowing for the wavelength, this short "Beverage"
worked very well.
I have copies of recordings made by Robert and was surprised by the very
good reception at his end [audible CW].
At John's "remote" site I believe that a 200m BOG would be well worth a
try on 500kHz.
Perhaps I should add that we have not yet achieved any access to the 500
kHz zone in ZL land. However, we have open access, all modes, all the way,
from 130 through to 190 Khz. The other good news is that the "power line
carriers", radiated from high-voltage power lines, have nearly all gone.
In the past, they made some parts of the LF spectrum quite unusable. We
just need a few more LF participants.
73,
Kevin, ZL4MD
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