Gary Schafer wrote:
Rather than a 50 ohm load how about if a load was placed at the end of
the coil to simulate the antenna, a resistor and capacitor to take the
place of the antenna impedance and reactance. Then measure the current
in and out and the phase shift.

The measurement problem is harder than it looks. Here's
a quote from "Field and Waves in Modern Radio", Ramo and
Whinnery, 2nd edition, page 227.

"Difficulties in applying these equations arise since
the current and charge distributions are not known, but
are determined by the field distributions which are
calculated from the retarded potentials which depend
upon current and charge distribution - a vicious circle!
The exact solution of this problem is usually of
prohibitive difficulty."
--
73, Cecil http://www.qsl.net/w5dxp