Szczepan Bialek wrote:

"W5DXP" napisal w wiadomosci
...
On Friday, July 27, 2012 12:50:32 PM UTC-5, Szczepan Bialek wrote:
Are the voltages doubled at the ends?

The voltage doubling at the ends of a dipole is simple to understand. A
dipole is a standing wave antenna. When the forward wave from the feedpoint
encounters the open-circuit at the end of the dipole wire, a reflection
takes place where the reflected voltage is in phase with the forward
voltage and the reflected current is 180 degrees out of phase with the
forward current.

Exactly like with the sound waves.

No, not quite.

At the end of the dipole, |Vfor|=|Vref| and |Ifor|=|Iref|. So the total
voltage and total current at the ends of a dipole a

Vtot = Vfor + Vref = 2*Vfor = 2*Vref

Itot = Ifor - Iref = 0

And of course, no current is going to flow into the open-circuit at the end
of the dipole so the total energy in the magnetic field at that point is
zero.

You assume that there no field electron emission. Why?

Because there isn't any because field electron emission is caused by
an electrostatic field and antennas have electromagnetic fields.

You have been told this several times; why do you continue to ask the
stupid question?

All of the energy in the EM waves migrates to the electric field and that's
why we get a standing wave voltage maximum at the ends of a 1/2WL dipole.

Nobody know what the EM waves are. Write about electrons.

Everybody reading the news group except you knows what EM waves are.

Electrons have nothing to do with a propagating EM wave.

You have been told this several times; why do you continue to make this
stupid statement?

However, under certain corona conditions, when the impedance at the end of
the dipole conductor is much less than infinite, electrons actually migrate
from the antenna into the conductive air, e.g. salty fog on the coast. But
this is undesirable non-coherent behavior unless you are building a Tesla
coil.

They migrate if the voltage is:
"Field emission was explained by quantum tunneling of electrons in the late
1920s. This was one of the triumphs of the nascent quantum mechanics. The
theory of field emission from bulk metals was proposed by Ralph H. Fowler
and Lothar Wolfgang Nordheim.[1] A family of approximate equations,
"Fowler-Nordheim equations", is named after them."

This has nothing to do with antennas because field electron emission is
caused by an electrostatic field and antennas have electromagnetic fields.

I once saw a mobile antenna emitting a red corona glow in the fog on HWY 1
near Monterrey, CA. A traffic cop stopped him for having a "red light" that
could be seen by oncoming traffic.

Each your antennas are the electron emitter:

No, they are not.

"How would the ideal field emitter look like? It should be very long and
very thin, made of conductive material with high mechanical strength, be
robust, and cheap and easy to process". From:
http://ipn2.epfl.ch/CHBU/NTfieldemission1.htm

Not all antennas are either long or thin; loop antennas work just fine.

The voltage doubling is only theoretical. In reality the voltage is rising
to the level necessary for effective field emissions.
If no proper voltage no radiation.

This pure, babbling, nonsense.

You are an ignorant, babbling, ineducable idiot who knows absolutely
NOTHING about how anything works.

You don't even understand what an antenna is or the difference between
an electric field, a magnetic field, and an electromagnetic field.

Electrostatic and magnetostatic fields are created by DC.

An antenna is a device that converts the AC electrical energy at its
teminals into electromagnetic energy which radiates from the antenna
and also coverts the electromagnetic energy which antenna intercepts
into AC electrical energy at it's terminals.

That is ELECTROMAGNETIC energy, not magnetostatic nor electrostatic
energy.

How many antennas have you built in your lifetime?

Why do you refuse to answer the question?

Is it because you have built zero antennas and you are trying to say all
the people that have successfully built hundreds that they are all wrong
and you don't want to admit you are an ignorant, inducable, idiot?

Why can't you obtain and read a university level textbook on anything in
any language?

Is it because you are too stupid to be able to understand the material?