DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
  s=s1024; d=btinternet.com;
  h=Received:X-YMail-OSG:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MIMEOLE;
  b=kCijRn3z9Gh0IXOoEaKNAnIVojKdYmncnTFMBXe66Oibqp/OqZTdRyybcA5/zWeKjS/N5RcPwQ1ETHRZ6I2/oRWfijtViDqnXeqTK5FobYmoroomHUgMR4uLccr0CcDzdRyz6OQUwDH8nT1umlgCEM/yk0ZWrNjqn7pKfeBVyns=  ;
Message-ID: <000701c83a7a$ed72bd40$0900a8c0@Lark>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <000901c83a65$6404c040$7f157ad5@w4o8m9>
Date: Sun, 9 Dec 2007 14:51:29 -0000
MIME-Version: 1.0
DomainKey-Status: good (testing) 
Subject: LF: Re: Antenna tests on 136k and 503k - Results
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


Hi Jim, I wondered whether that was your objective with the "portable site".
That is a very interesting confirmation of some of the "thinks" a lot of us
have had about ERP calculation and the environmental effects. Well done,
nice project.

One small comment on the open field aerial, your loss figures confirm the
advisability of having extensive top-wires to increase the aerial capacity
and so enable a higher Q coil to be more easily achieved. In this situation
the top-wires may not add much in terms of ground loss reduction. It is also
possible that in this situation an advantage would be seen in helically
winding the vertical section too. In most cases the Rrad advantage of
helical winding (only about 15-20% I think)  is probably negated by the
increased capacity to the lossy surroundings.

I suppose you could see the Rrad reduction due to nearby structures and the
environment as being due to some of the feed current being diverted by
capacitive coupling into the lossy surroundings and so not traversing all of
the distributed Rrad.

I am pleased you managed to finish that work before the wind and weather
made it too uncomfortable being out in the middle of a field !!

Cheers de Alan G3NYK

----- Original Message -----
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Sunday, December 09, 2007 1:14 PM
Subject: LF: Antenna tests on 136k and 503k - Results


> Dear LF Group,
>
> I have now finished the antenna experiments that I started earlier this
> week - this is a summary of the results.
-------snip