On Tue, 21 Oct 2008 13:30:39 +0100, Ian Jackson
wrote:

Are there any calculations or charts for centre impedance of a dipole in
free space, starting from zero length, and going out to infinity?

Institutional memory here is so slight:

"Theory of antennas of arbitrary size and
shape," Proc. I.R.E., 29, 493, 1941 and S. A. Schelkunoff, "Advanced
Antenna Theory, " John Wiley and Sons, Inc., New York, (1952)

Accessible reference work can be found by searching the PTO with his
patent number: 2235506.

73's
Richard Clark, KB7QHC