"Ian Jackson" napisal w wiadomosci
...
In message , Rob
writes
Szczepan Bialek wrote:
The "dipole" where one element is connected to "live" wire and the
second
to a "ground" is the monopole.

It is your misunderstanding that:

1. amateurs always connect coax directly to a dipole. they don't.
those that are in the know will use a balun.

In the past, many amateurs did connect coax directly to a dipole.

And what they do if they have the monopole?

The reason is that - on most occasions - it worked perfectly well, and they
'got away with it'. It was only when problems occurred (interference to TV,
radio, Hi-Fi etc) that much thought was given to the need for a balun.

And what if somebody have the monopole with the radials?

In modern times, there is a lot more opportunity for amateurs to interfere
with - and suffer interference from - all kinds of domestic equipment, and
the use of a balun (or twin feeder) has more-or-less become an absolute
necessity.

The twin feeder ensure the electrical symmetry.

2. the braid of the coax is "ground". this is not true. there will
be voltage at the braid of the coax at the antenna end when a balun
is not used.

Szczepan is obviously making the fundamental mistake of thinking that,
because the coax screen is grounded at the transmitter end (or at least
connected to the chassis of the transmitter), it is therefore at zero RF
potential - and that it is still at RF potential at the far (antenna) end,
where it is connected directly to the 'other' leg of the dipole. This is
wrong.

I know that in the coax screen something is induced. But I am sure that
such "dipole" is not electrically symmetrical.

He is then assuming that if the coax screen is at zero RF potential where
it is connected to the other leg of the dipole, then the other leg of the
dipole is also at zero RF potential (and doesn't radiate). This is wrong.

I am sure that the other leg radiate almost nothing.
In Hertz time all scientists investigate which part of the Hertz apparature
radiate.
He is therefore concluding that as both the coax screen and the other leg
of the dipole are at zero RF potential, the only part of the antenna
system that is 'RF live' is the leg of the dipole which is connected to
the inner conductor of the coax - which is what happens with a monopole.
As a result, he is then claiming that a dipole is really only a monopole.
This is wrong.

I am only claiming that it works like the monopole.
In your literature is wrote that "monopole with the counterpoise works like
the dipole". But in your literature the dipole means the mechanical
symmetry.

However, I'm still convinced that Szczepan knows far more about radio than
he appears to, and is cunningly trying to get us to explain phenomena
which maybe we really don't know as much about as we like to think we do!

Exactly.

But if I am right than the "counterpoise" leg of your dipole should be made
of the proper material and have the proper dimenssion not necesary the same
as the "live" leg.
So I start the new thread "Joels question".

The history of radio-amateur is so long that that issue is probably solved
long ago.
S*