[TowerTalk] Coefficient of coupling

[Rick Karlquist]

Steve wrote:
> Just wondering if there's a way to determine coefficient of coupling
> based on the physical dimensions of the two coils and their mounting
> with respect to each other?

Of course, F. W. Grover figured this out a century ago.

Grover, "Formulas and tables for the calculation
of mutual and self inductance", NBS Paper 169, 1912.
(NBS is now NIST)

Grover, "Tables for the Calculation of the
mutual inductance of any two coaxial single
layer coils", Proceedings of the IRE,
July 1933 pp 1039-1049. (IRE is now IEEE).
This paper claims to have easier to calculate
formulas.  Of course that was precomputer.  Not
clear which would be easier now.

I have the latter paper in my personal library.  I can
scan it in if you can't find it at your local engineering college.
I also have the NBS book, but it is fairly lengthy to scan in.

> Didn't find it in the Handbook, nor did a google search turn up anything.

Google on "grover" and "inductance" and you'll get a bunch of hits.
>
> Steve K8JQ

I can tell you ahead of time that it is difficult to get coupling
above 50% and impossible above 80% or so.

Rick N6RK