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R: LF: Re: Loop Conductors and proximity effect Rdc Rac

To: [email protected]
Subject: R: LF: Re: Loop Conductors and proximity effect Rdc Rac
From: "cesare tagliabue" <[email protected]>
Date: Fri, 22 Mar 2002 07:18:11 +0100
Reply-to: [email protected]
Sender: <[email protected]>
        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: [email protected]
url: http://www.dadacasa.com/i5tgc
-----Messaggio originale-----
Da: john sexton <[email protected]>
A: [email protected] <[email protected]>
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: [email protected]
> url: http://www.dadacasa.com/i5tgc
>
> -----Messaggio originale-----
> Da: john sexton
> A: [email protected]
> 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
>
>
>
> ----------------------------------------------------------------------------
>
>
>


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