Return-Path: Received: (qmail 19591 invoked from network); 19 Mar 2002 11:00:25 -0000 Received: from unknown (HELO warrior.services.quay.plus.net) (212.159.14.227) by excalibur.plus.net with SMTP; 19 Mar 2002 11:00:25 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 7455 invoked from network); 19 Mar 2002 11:00:21 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior.services.quay.plus.net with SMTP; 19 Mar 2002 11:00:21 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 16nIm3-0001FE-00 for rsgb_lf_group-outgoing@blacksheep.org; Tue, 19 Mar 2002 12:31:31 +0000 Received: from nat3.excitenetwork.com ([63.236.75.5] helo=xmxpita.excite.com) by post.thorcom.com with esmtp (Exim 3.33 #2) id 16nIm0-0001F2-00 for rsgb_lf_group@blacksheep.org; Tue, 19 Mar 2002 12:31:29 +0000 Received: by xmxpita.excite.com (Postfix, from userid 110) id 5A920299FB; Tue, 19 Mar 2002 05:52:54 -0500 (EST) To: rsgb_lf_group@blacksheep.org Subject: RE: LF: Re: Loop Conductors and proximity effect Rdc Rac From: "john sexton" MIME-Version: 1.0 X-Sender: computernetworks@excite.com X-Mailer: PHP Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Message-ID: <20020319105254.5A920299FB@xmxpita.excite.com> Date: Tue, 19 Mar 2002 05:52:54 -0500 (EST) Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Hi Cesare,
Funny thing, I too wasted a lot of time yesterday messing about with Excel trying to find a fit and the best I came up with was that it was approx. k/log(D/d). Polynomial fits didn't seem to work too well.

Thanks for the formula. It doesn't quite work though for values of D/d from 2 to 4, but perhaps the data were only approximations?

The data alone are pretty useful. Looks like that time at College wasn't entirely wasted, hi!
BTW Bill pointed out that the minimum separation can be small as you like if you use Litz wire and can get Rrf down or close to Rdc, because
Reff/Rrf = 1 + (q - 1) * SQRT (1-Rdc/Rrf)
reduces to 1 when Rdc = Rrf as an alternative to q = 1.

Thanks again.
73, John, G4CNN

--- On Mon 03/18, cesare tagliabue wrote:
> Hello John
> I have found the Mesny's expression on an old university stenciled
> book where only the data were given, but some time ago, for purpose of
> include it in a program, I have elaborated an empiric expression that
> approximates sufficiently these data. That is:
> q = ( 1 + .95 d / D )^2 -
> .22
> Best 73 to all Cesare
>
> Cesare Tagliabue I 5 TGC
> WW-Loc JN53PS
> e-mail: cestag@dada.it
> url: http://www.dadacasa.com/i5tgc
>
> -----Messaggio originale-----
> Da: john sexton
> A: rsgb_lf_group@blacksheep.org
> Data: lunedė 18 marzo 2002 17.46
> Oggetto: LF: Loop Conductors and proximity effect Rdc Rac
>
>
> Hi Paul,
> From the interesting formula given by Cesare, the short answer to your
> question appears to be 1/2 inch.
> I tried to find out more about Mesny's expression from the Internet,
> but it looks like you have to buy the book.
> I wonder whether Cesare can be persuaded to tell us the formula that
> relates q to D/d? At a guess it appears to be logarithmic.
> The second formula can be simplified to
> Reff/Rrf = 1 + (q-1)*sqrt(1-Rdc/Rrf)
> When D/d = 9, q = 1 so the second term disappears and Reff = Rrf.
> 73, John, G4CNN
>
>
>
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