"Szczepan Bialek" wrote in message
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"Dave"
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"Szczepan Bialek" wrote in message
...

In the Gas Analogy the monopole antena is exactly like the Kundt's
tube.

Heaviside did the Hydraulic Analogy. All is exactly the same like in
the fluids mechanics.
Next the electrons were discovered. Automatically Heaviside is a
history and the Gas Analogy is in power.

But you, radio people, are very close to waves and should be easy for
you to work out the answer for the Question:
Which Analogy is right?

neither analogy is 'right'. they are useful in limited circumstances
to demonstrate some basic pressure wave physics to young students. but
neither one properly reproduces electromagnetic waves.

"electromagnetic waves" are paper waves. Radio waves are real waves. Now
we must not know what the waves are like. Now we should estabilish from
which part of the radiator radiate the radio waves.
Do you agree with Richard Harisson:
"At the open circuited ends of a resonant antenna there is almost double
the forward voltage but zero total current due to cancellation of the
dorward and reflected currents at the open circuit. At the open circuit
in the wire, all the energy in the wave is transferred to the electric
field."
S*


we know what they are like, you just have to understand the mathematics.

I understand. Without that it was be impossible to know that Maxwell
proposed the displacement current to save the incompressible electric
fluid. In Maxwell times AC current was known. To pass the incompressible
fluid through a capacitor the displacement current is necessary. I prefere
the compressible electrons. They compress in the plates and nothing flow
between them. The polarization is not the macro flow.

and yes, richard's statements are true, but a bit too restrictive, it
doesn't HAVE to be resonant. Voltage doubles and current=0 at the end of
any wire fed with a time varying current, it doesn't even have to be a
sine wave... note the effect of sending square waves from a time domain
reflectometer down an open circuited wire.

Yes. But antennas are in resonance.
S*

antennas don't have to be 'in resonance'.... a very short dipole radiates
almost as well as one 1/2 wavelength long... its all in the fields.