In message , Reg
Edwards writes
What is the impedance at the centre of an infinitely long dipole
(in
free space)?

===============================
Its not very different from -

Zin = 120 * Ln( Wavelength / d ) ohms.

where d = conductor diameter, both measured in metres.

Thus, at wavelength = 80 metres with 14 gauge copper wire, input
impedance = 1300 ohms approx.

If you don't believe me, just measure it.
----
Reg.



Are you sure it's as high as that, Reg? I once did a Smith Chart plot of
the impedance at the centre of a dipole, the valued being taken from a
table 'compiled by Wu' (LK Wu?). These only catered for a lengths up to
a few wavelengths. As the plot progressed round and round the Smith
Chart, it seemed to be heading for something around 350 to 400 ohms.

I've just done a search on 'Wu+dipole+impedance', and one of the results
is
http://www.fars.k6ya.org/docs/antenn...nce-models.pdf
I'll have a read of it today.

Cheers,
Ian.
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