Richard Harrison wrote:
Roy Lewallen wrote:
"OK, I give up. I`ve got a dipole in free space. I connect one end of
the load resistance to one end of the dipole. What do I connect the
other end of the resistor to?"

Great question. You connect it to the inobtrusive convenient perfect
earth connection immediately present at the end of the terminating
resistor. Since this is likely impossible, you merely define you have
done the deed and calculate the results.

Another way to mentally view the surge impedance is with
an infinitely long wire for the dipole. It changes the
dipole from a standing-wave antenna into a traveling-
wave antenna. The ratio of V to I is constant and equal
to the characteristic (surge) impedance of the antenna.

Reg claimed the feedpoint (surge) impedance for an infinite
dipole would be about 1200 ohms, i.e. ~600 ohms in each
direction which roughly agrees with the formula 138*log(4D/d).
--
73, Cecil http://www.w5dxp.com