Walter Maxwell wrote:
. . .
One of the reasons I offered to distribute the data from my
measurements is to see whether anyone can deduce any soil
characteristics from the changes in impedance with height. The
changes are significant. For example, the terminal impedance with the
dipole on the ground runs from 470 + j250 at 14 MHz to 570 + j132 at
15 MHz. The inductive reactance doesn't become capacitive until the
dipole is 2 ft off the ground. In addition, except at zero height,
the resistance component decreases with height, but for every height
the resistance increases with frequency. Do you think any of the soil
characteristics could be determined by such data?
. . .

I haven't looked into this carefully, but one person I know who was very
involved in NVIS operation (where ground characteristics are important)
tried it some years ago. He concluded that it wasn't possible to
set the antenna height and make measurements with sufficient accuracy to
infer the ground characteristics with any confidence.

Roy Lewallen, W7EL