Re: optimal aspect ratio

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<herwig.roscher-at-gmx.de>
> 
> Fellow coilers,
> 
> The latest edition of a German radio amateur magazine is dealing with
> the optimal aspect ratio of cylindrical single layer air core coils
> (like the solenoid type primaries in our TC systems).
> 
> The author proofs, that coils with an aspect ratio length/diameter of
> 0.45 provide maximal inductance and minimal resistance.
> 
> The number of turns is calculated from
>                                                 7.43 x 3rd root(L in
µH/dia in mm)
> 
> Unfortunately there is no URL available (the publisher wants to sell
> the copies of course).
> 
> Cheers,
> 
> Herwig

	Fortunately, the optimum is so weak a function of AR that it hardly
matters if the coil is "best shape", or "square" or has an l/d of 2. 
Because of "skin effect" [eddy current losses] the exact answer has to
be frequency and wire spacing dependent.

Ed