Richard Harrison wrote:
"Ro = 60 times the intergral, zero to pi, ...

Heh, heh, since you don't know the last digit of pi, Roy
probably won't allow you to use it. :-)

Where the radiation resistance Ro is referred to the current maximum.

The point seems to be that the impedance at the current maximum
point includes terms besides radiation resistance. In simplified
form, for a resonant antenna, Rfeed = Rrad + Rloss

Rloss includes I^2*R losses and ground losses and is sometimes
negligible and sometimes not.

For some antenna configurations, Rloss is negligible, so the
feedpoint resistance can be very close to the radiation
resistance, e.g. a dipole in free space.

For other antenna configurations, Rloss is much greater than
the radiation resistance, e.g. an 8 foot center-loaded 75m
mobile antenna.

My screwdriver has approximately a 12.5 ohm feedpoint resistance
on 75m. I consider approximately 10 ohms of that to be ground
loss.
--
73, Cecil, W5DXP