Return-Path: Received: (qmail 12184 invoked from network); 22 Mar 2002 06:28:13 -0000 Received: from unknown (HELO murphys-inbound.services.quay.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 22 Mar 2002 06:28:13 -0000 Received: (qmail 945 invoked from network); 22 Mar 2002 06:28:11 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys.services.quay.plus.net with SMTP; 22 Mar 2002 06:28:11 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 16oJwH-0002eI-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 22 Mar 2002 07:58:17 +0000 Received: from mail5.dada.it ([195.110.96.37] helo=mail.dada.it) by post.thorcom.com with smtp (Exim 3.33 #2) id 16oJwF-0002eD-00 for rsgb_lf_group@blacksheep.org; Fri, 22 Mar 2002 07:58:16 +0000 Received: (qmail 20077 invoked from network); 22 Mar 2002 06:19:36 -0000 Received: from unknown (HELO cestag) (195.110.103.107) by mail.dada.it with SMTP; 22 Mar 2002 06:19:36 -0000 Message-ID: <001401c1d169$6af38500$6b676ec3@cestag> From: "cesare tagliabue" To: rsgb_lf_group@blacksheep.org Subject: R: LF: Re: Loop Conductors and proximity effect Rdc Rac Date: Fri, 22 Mar 2002 07:18:11 +0100 MIME-Version: 1.0 Content-Type: text/html; charset=windows-1252 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.3110.5 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Content-transfer-encoding: 8bit

Hi John

I've also tested some polynomial expressions, the best seems to be a 5th grade one, that is:

7.074632 - x 5.16214 + x^2 1.870903 - x^3 .3380672 + x^4 .02977327 - x^5 .001017036 but the values are not matched properly. 73 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 <computernetworks@excite.com>
A: rsgb_lf_group@blacksheep.org <rsgb_lf_group@blacksheep.org>
Data: martedì 19 marzo 2002 12.05
Oggetto: RE: LF: Re: Loop Conductors and proximity effect Rdc Rac

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: lunedì 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
>
>
>
> ----------------------------------------------------------------------------
>
>
>