"Cecil Moore" wrote
...
On May 21, 1:07 pm, "Szczepan Bialek" wrote:
Alternate electric field from the ends of the dipole kicks the electrons
in
the space and they oscillate (longitudinal electric waves).

How much I^2*R loss is there in the plasma conductors of free space?

Oscillations are not travelling. Loss are only when something travel between
obstacles.

How far into space does the electron plasma effect extend?

As far as light do.

If electrons can flow from a cold aluminum element in a vacuum, why does
a vacuum tube need a special heated cathode?

Also exists the field emission. But it is harmfull for antennas if it is in
form of sparks.
The high voltage kicks the electrons in the neighbourhood.
Probably the electrons flow (and come back - but it is not symetrical)) from
a cold aluminum element. Anenna radiate if VSWR is low. It means that not
all come back.
S*