Measuring Antenna Capacitance

...not bad. And now its a small exercise for you to substitude k and a by terms with L und d. Perfect formula for this special case.  

Too few points to select realistic functional dependencies.

(for example: the behavior of parameter "a" is unclear on the interval L=0...20 cm, whether it tends to 1, or to another value)

For practical purposes (in order to obtain intermediate values of "a" and "k"), it is sufficient to have a piecewise linear interpolation or approximation by a 2-nd order polynomial (as anyone likes).

I think it's amazing that you come up with this idea. Hope I can have this kind of experimental spirit!

New version (v1.18) of Theremin Explorer is avalible now.

Features:
- new antenna types added : "plate" and "curved rode"  (*),
- export of curve to table,
- "disable" mode for auto-calculating of Fixed Oscillator frequency,
- "session" file to create group of curves,
- "critical value" calculations for double coil circuits,
- more configuration files -- more different theremins.

(*) Patent RU 2701449.

Thanks ILYA!  Very nice to have tools that demystify the general BS in this field.

(It runs fine in Linux Mint via Wine!)

Is that a tinfoil Peter Pringle?

Yea,
l'uminium Peter, a frend of your miss-capacitiss Clara.

Picofarad Peter Pringle!

Checking condition

It's interesting to check how much the setup is stable after years of storage.

I measured a reference capacitor 49.75 pF (two "100 pF" in series) and get the value 49.81 pF.
Excelent result! However, just in case, I recalibrated the setup again.

The next step was to repeat the capacitance measurement for an antenna used in 2016. I chose a rod 40 cm length and 7 mm diameter.
Results are shown below. As you can see, the different year curves are almost overlapped, which allows you to use old results for comparison purpose with the new ones.