Richard Clark wrote:
The drivepoint Z is NOT the
"radiation resistance" irrespective of loading transformation. You
can build a very small radiator, load it to resonance and it offers
extremely poor efficiency.

The ARRL Antenna Book says the feedpoint impedance of an
8 foot center-loaded mobile antenna on 80m is 22 ohms
while the radiation resistance is 0.8 ohms.
--
73, Cecil, W5DXP