Re: K Factor & Mutual Inductance

        Re: K Factor & Mutual Inductance
        Mon, 7 Apr 1997 16:33:40 -0700 (PDT)
        "Edward V. Phillips" <ed-at-alumni.caltech.edu>

"We normally think of coeff. coupling being independent of system power,
if you ignore the effects of additional electric field capacitance above
the sec. coil (usually on 5% or less anyway) then the coeff. coupling
measurements should be the same with a sig. generator and scope vs. a
powered up system.  Does your equations somehow tie "power" into the
coupling equation??"
        The standard of definition of coupling coefficient refers to
inductive magnetic coupling, and is a function only of the mutual
inductance and the primary and secondary inductance.  In calculating
COUPLED POWER between resonant circuits it is, of course, necessary 
to take into account circuit tuning, Q, and all circuit strays.
Furthermore, in the case of Tesla coils, the primary and secondary
circuit losses are dominated with nonlinear and time-varying terms,
so that any exact analysis is probably beyond the reach of even a
very sophisticated computer simulation.  "Rules of thumb" and simplified
computer programs can be of use in guiding the preliminary design of
a system, but experimental tuning and general "fiddling around" are
certainly required for optimizing things.