Re: Capacitance of a coil

Tesla List wrote:
> Original Poster: Bryan Work <bryan-at-apexrad-dot-com>
> Your post stimulated some (meager) comprehension on my part; reaching
> outside the box brought to light the following:
> 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

> 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


The coil's height is 31" and the diameter is 10.25 making the H:D =

-- Bert --