Peter O. Brackett wrote:
. . .
In my opinion such a determination would be a very difficult
experimental/engineering exercise. The experimenal problem is one of how
does one vary the Zo of a media while measuring the effect on the Z at the
driving point? Here's a thought experiment...

Immerse an antenna in a liquid media with a given u and e in an anechoic
tank then drive the antenna with a generator while measuring the driving
point impedance (V and I) and then pour or mix in some other liquid with
different u and e and observe the change in Z.

Would that work?

It could also be accomplished numerically on a computer by using a program
[like the NEC programs] based on solving Maxwell's partial differential
equations iteratively.

As far as I know no one has ever attempted to do this... and notwithstanding
the possibility for "invention" or "discovery" I might ask, why would one
want to do this?

Hey it might make a good Ph.D. or M.Sc. thesis... but what is the practical
application?
. .

It would be one of the easiest degrees ever attained. NEC-4 allows
setting the primary medium to any (reasonable) value of conductivity and
permittivity, so you can have the answer in seconds with a free space
analysis. Alternatively, you can bury the antenna deep in NEC-4's ground
medium and define the ground characteristics for your test.

I did a short consulting job a while back for some people interested in
transmitting RF for short distances under water. Immersing the antenna
eliminates the substantial signal loss incurred by reflection at the
air-water interface when the antenna is out of the water. And antenna
system design requires knowledge of the antenna feedpoint Z. I've seen
numerous papers in the IEEE publications about antennas immersed in
other media such as a plasma, and know that antennas buried in the
ground are used. So it's of considerable practical interest.

Roy Lewallen, W7EL