Message-ID: <007101bfc16d$448312e0$c4804dd1@tractorb>
From: "Dave Brown" <tractorb@ihug.co.nz>
To: "rsgblf" <rsgb_lf_group@blacksheep.org>
References: <28528.200005171129@gemini>
Subject: LF: Re: Puckeridge Decca station - Big & small antennas
Date: Fri, 19 May 2000 20:35:55 +1200
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Jim
Probably not this time, but a suggestion for perhaps next time you go to
Puckeridge.
 I mentioned this to Derek Atter, after I saw the picture of the antenna, as
a possibility for an interesting experimental comparison.
 Basically, as the antenna is set up, it appears to be a  vertical elongated
umbrella structure with the eight downwires or 'top loading' wires extended
down nearly to ground level, quite close in to the mast proper. The reasons
for this were explained on the reflector some time back.
I am interested to know what the effect of temporarily connecting the bottom
ends of all eight down wires back to the insulated tower base might be. The
screening effect of all those down wires should be significant.  By
connecting them to the tower base they should then become part of a somewhat
'thicker' vertical structure with no downwire screening.
 I expect that you would then need more inductive loading, BUT  it would be
very interesting to see what the remote (ie far field) field strength did.
Unless there is something very 'cunning' in the design of the antenna (which
I doubt, given the history of the present day structure!) my guess is that
it would go up, but  I have no idea by how much.

Just a thort!
Good luck with the experiment this time.

73
Dave, ZL3FJ