Re: tuned coils

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>



> Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
>
> Hi Robert,
>
> Wow!  A REAL energy transmission experiment! :-)
>
> Here is my guess as to doing it.  I would get one fairly standard Tesla
> coil and set it at point A.  Then I would get another secondary coil with
a
> toroid and ground rod (a smaller removable one) so that you could set the
> second coil up at various distances from the first coil.  Then I would try
> and make some kind of signal strength or current meter to put into the
> ground lead from the second coil to measure the current (our HAM radio
> friends may have ideas on that).  Of course, the two coils should be tuned
> to the same fundamental frequency.
>
> Once you have the stuff, you can measure the current in the second coil at
> various distances.  Then you can make a graph.
>
> I think Richard Hull and a few members of the TCBOR have done this.
> Perhaps they have more information.  "I" think every time you double the
> distance, the current will drop to 1/4.  But hopefully your REAL data will
> prove or disprove that.


Hmmm.. I think you are definitely in the near field, so inverse square may
not hold.  At very small (relative to a wavelength) distances, magnetic
coupling is significant, and the magnetic field may drop off very
differently than inverse square.

All in all, a fascinating experiment... Getting good calibrated results
doesn't require fancy equipment (a voltmeter that can accurately measure RF
voltage), just attention to detail and a bit of tedium. This is the sort of
measurement made on antenna ranges every day.