On Sun, 12 Oct 2014 15:01:19 -0700, Jim Thompson
wrote:

...snip...

Me, too! IKEA bookcases ;-)

...Jim Thompson

See reply to what3rd who did an excellent 'rule-of-thumb' estimate.

I was VERY surprised to see approximately 0.1 coupling!

If you're stuck on using this approach, and need a model; I've already got
the .asc running for various positions. However, it's easy to do a curve
fit and produce k vs position, too.

Is this for isolation? high voltage separation? Have you thought of using
those cheap LED 'handheld remote controllers' They transmit quite a
distance, cost nothing and run on nothing, ...well almost. but you get to
piggy back on VOLUME production costs. Bunch of chipsets out there.