Nic. Santean wrote:

We are talking about half wavelength dipole antennas, right ?

Yes. A 1/2WL dipole can be thought of as a very leaky transmission
line. It has standing waves that leak radiation into the Æther. :-) May
I suggest trying to understand traveling-wave antennas before getting
into standing-wave dipoles? Consider a terminated V-beam or terminated
Rhombic to eliminate the confusion associated with reflected waves. But
don't feel bad about confusion associated with reflected waves. Some of
the r.r.a.a gurus don't understand reflected waves and the energy plus
momentum involved in their very existence. So many sacred cows - so
little time. :-)

Methinks the situation is a little more complicated than that. The
E-field and H-field is in phase at the feedpoint of a resonant
dipole. In the real world, they are never 90 degrees out of phase,
but they get close to 90 degrees at the points midway between the
feedpoint and the ends of the resonant dipole. The E-field and H-
field are (almost) back in phase at the ends of the dipole.

The ratio of net total voltage to net total current at points along
a dipole can be thought of as a spiral on a Smith Chart. It is much
like a transmission line where the spacing between wires is too large
for the frequency of operation and therefore leaks radiation.
--
73, Cecil http://www.qsl.net/w5dxp



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