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Re: Capacitance of a coil
Tesla List wrote:
>
> Original Poster: Bryan Work <bryan-at-apexrad-dot-com>
>
<SNIP>
> Your post stimulated some (meager) comprehension on my part; reaching
> outside the box brought to light the following:
>
<SNIP>
>
> The capacitance is also not just between adjacent wires but also between
> each pair of wires in the loop with diminishing contribution with distance
> and with integration of eq. (2) we derive eq. (1)
The capacitance to the groundplane seems to be the most relevant, not
the inter-turn capacitance...
>
> I apologise for the non-rigorous treatment here, Time is a factor. If
> permitted I will pursue this furhter later if anyone desires.
>
While a usable closed-form solution would be a bit more satisfying than
a simple lookup table, practically speaking Medhurst's table (or a
curve-fitted equivalent) seems to provide quite accurate predictions,
and can be easily integrated into a spreadheet via the VLOOKUP
function...
<SNIP>
> There also seems to be another factor not include in the original equation
> of the L/D ratio. I would expect that given Bert's information his coil's
> L/D is 4.1. Is that so Bert?
>
> Bryan Kaufman
Bryan,
The coil's height is 31" and the diameter is 10.25 making the H:D =
3.02.
-- Bert --