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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
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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