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Old September 15th 09, 05:58 PM posted to rec.radio.amateur.antenna
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Default Spherical radiation pattern


"Cecil Moore" wrote
...
joe wrote:
Look at the antenna current as an electron oscillating
back and forth between the ends.


At HF frequencies, the electrons move hardly at all, tending
to oscillate back and forth in place. The idea that electrons
race from end to end in an antenna is simply false.

http://c2.com/cgi/wiki?SpeedOfElectrons

"... for a copper wire of radius 1 mm carrying a steady
current of 10 Amps, the drift velocity is only about
0.024 cm/sec!"

For a 100w 10 MHz RF wave, you can divide that distance by
more than 10,000,000. Exactly how far can the electron travel
in 0.05 microsecond?

It is the photons emitted by the electrons that travel at
the speed of light in the medium. That's the fields surrounding
the antenna conductor, not the electrons in the conductor.


It is for students. Hall and others developed technics to estimate how many
electrons are free in different metals.
It is not one per atom.
S*
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com


 
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