"christofire" wrote
...

"Szczepan Bia³ek" wrote in message
...



You appear to have changed your identity from S* to A* !
Sorry. Mistake (A is adjacent to S).

The answers according to the physics that real-life radio communication
depends upon, and was designed by, a

A single EM wave is plane polarised. It is composed of a magnetic field H
that acts in a direction perpendicular to the direction of propagation,
the magnitude and sign of this field varying as a travelling wave in the
direction of propagation, and an attendant electric field E that also acts
in a direction perpendicular to the direction of propagation. The
magnitude and sign of the electric field varies as a travelling wave,
coherent and in phase with the magnetic field and the magnetic field is a
direct consequence of current flowing in the transmitting antenna.

But there is the second direct consequence. If the current oscilate at the
ends is developed the very high voltage. The high voltage produce the
electric field. So you can wrote: "the electric field is a direct
consequence of voltage developed in the ends of the transmitting antenna".
This electric field generate the magnetic field and so on. So the Hertz'
dipole has the three sources of waves. The centre and the two ends.
It seams that waves from the centre are mainly transverse and that from the
ends mainly longitudinal.
Long wire antennas have many sources. Directional patern is number source
dependent.

You do not like the word voltage. May be the better is polarity.

R. Clark wrote: "Actually you have mixed up two different characteristics.
Polarity
and polarization are NOT the same thing. With RF radiation, the wave
is constantly changing polarity (that is why the source of RF is
called alternating current), but within the "line of sight" of the
antenna, the polarization for a dipole is defined by its angle to the
earth as viewed by the observer.

If you see an horizontal dipole, it produces alternating polarities of
waves with horizontal polarization. If you see a vertical dipole, it
produces alternating polarities of waves with vertical polarization."


The directions in which the
H and E fields act, in the plane transverse to the direction of
propagation, are mutually perpendicular and the direction in which the E
field acts, by convention, defines the polarisation.

Thus a single EM wave has a single, plane, polarisation. Different
combinations of waves are possible such as circular polarisation and, more
generally, elliptical polarisation, but these can always be resolved into
orthogonal plane components.

Simple antennas like straight-wire dipoles and loops transmit and respond
to plane polarised EM waves. More complicated antennas can be made to
transmit and receive circular polarisation of one sense or the other, and
generally an antenna will tend to transmit or be sensitive to some
combination of different plane polarisations. In addition to radiated EM
waves, there are also induction fields in a region close to the antenna.

In a system that contains no anisotropic material (e.g. magnetised
ferrite), when the distance between transmitting and receiving antennas is
at least tens of wavelengths, the principle of reciprocity applies. By
this principle the properties of an antenna when transmitting are the same
as when it is receiving - the properties including the polarisation,
radiation pattern and terminal impedance.

If you find any of this interesting, please don't believe what I've
written here but go to a technical library (e.g. at a University) and look
up the authoritative sources - books on antennas and propagation by Kraus,
Jasik, Jordan and Balmain, Terman, etc.

Do they use the vord voltage?

Please _do not_ respond here telling me or the group that EM waves are
longitudinal and are not polarised.

EM waves by Heaviside are transverse. Now we should check if he was right.
S*