Szczepan Bialek wrote:

"Rob" napisa? w wiadomo?ci
...
Szczepan Bialek wrote:

"Rob" napisa3 w wiadomo?ci
...
Szczepan Bialek wrote:
If it were true, an antenna
would be a nonlinear element that would cause intermodulation. As we
don't see that happen on a well-designed antenna (it *does* happen
when
there are bad contacts with diode-effect in the antenna), we know that
an antenna by itself cannot be nonlinear and so there cannot be a net
flow of electrons.

The net flow of electrons is from the counterpoise to end of antenna.
S*

How do you explain that there is no intermodulation as a result of
the nonlinearity of the antenna that you claim?

I am here to learn.

Please don't wander off the subject and answer the question!
You did not answer the question why there is no intermodulation
in a transmitter antenna, while you claim it is nonlinear.

All is linear in the textbooks (necesary simplification).
In reality all is nonlinear.

This is meaningless babble.

While lower level, i.e. grade school textbooks, may contain simplifications,
university level textbooks do not.

I would bet heavily that you have never read any textbook beyond the grade
school level.


Lately I have learn from Bilou:
"In such cases it is convenient to put the things to their limits.
Imagine the diameter of one half is infinite.
You now have a quarter wave over a ground plane.A well known case."

It means that a dipole fed from a coax is the monopole (a quarter wave)
with
the counterpoise.

"In the case of very rocky or poorly conducting soil a counterpoise often
is
substituted for a buried network of wires. A counterpoise is a network of
wires place above the earth a slight distance and insulated from it, so
arranged to produce a very high capacity to the earth."

So I know now why you all claim that a dipole do not need a ground.

Because a dipole does not need a ground, it is a symmetric antenna which
is not driven relative to ground.

Do you mean the antenna with the two legs where the one leg is connected to
the shield of a coax?

There is nothing that requires a dipole to be connected to coax.

In fact many dipoles are connected to balanced line all the way to the
transmitter.

Those that are connected with coax usually have device between the coax
and the dipole to convert from unbalance to balanced.

Again you show you know nothing about antennas or the real world.


The number of radials is the power dependent. More power radiated more
electrons must be taken from a ground.
Do you agree?
S*

No.

For what are sometime the 120 radials?
S*

One more time, the number of radials needed for good perfomance for an end
fed monopole, and ONLY an end fed monopole, depends ONLY on the ground
conductivity.

Dipoles do NOT need radials.

Yagis do NOT need radials.

Loops do not need radials.

Slots do not need radials.

Horns do not need radials.

Rhombics do not need radials.

Stermba curtains do not need radials.

Log-periodics do not need radials.

Helicals do not need radials.

Only end fed monopoles need radials.