"christofire" wrote
news

"Szczepan Bia³ek" wrote in message
...


-- snip --


* Would you care to cite a reference where it is stated that EM waves in
the far field of a transmitting antenna contain a significant
longitudinal component? Many respected authors, such as Kraus, have
illustrated the contrary, but their work isn't limited to paper; people
like Kraus have designed real antennas of types that are still in use
today.

Maxwell ASSUMED that the aether is a solid body and ASSUMED that there
are the transversal waves. Next he do the math to it. To prove it he asks
Michelson to measure the movements of the Earth in this solid body. In
1878 (about) Michelson did not detect 30km/s. In 1925 he detect 0.4 km/s.
It means that the eather is not a solid body. The EM theory is only math
(a piece to teach).

* You haven't cited a reference. The words you have written here do not
demonstrate that EM waves are longitudinal. A 'reference', if you didn't
understand the term, means a passage from a book or paper written by
someone who has a proven reputation for good, useful work in the field.

" Oliver Heaviside criticised Helmholtz' electromagnetic theory because it
allowed the existence of longitudinal waves" .From:
http://www.answers.com/topic/hermann-von-helmholtz

Do you know somebody who has more proven reputation in acoustic and
electrodynamics than Helmholtz?
Hertz was the pupil of Helmholtz.
The Maxwell's equations (that from 1864) was the same like the Helmholtz'
for fluid mechanics.
Many textbooks inform us that it was a big Maxwell's mistake. He ignored
atomic nature of electricity disovered by Faraday at electrolise. Helmholtz
not ignored it.
Maxwell (modified by Heaviside) is only a piece to teach the math.


Sound waves are longitudinal because air pressure is a scalar, whereas
electric and magnetic fields are vectors - they have polarisation.

The math has not to do here.

* What 'math'? ... just the mention of scalars and vectors, in a group
devoted to antennas. Please.

The first step should be dicovering which part of the oryginal Hertz
dipole radiate:
http://people.seas.harvard.edu/~jone...Hertz_exp.html

The big sparks (current) or the plates (balls).
Note that todays dipoles are quite different. Now no current between the
tips.


Here is the full acoustic analogy. The two loudspeakers work like the
two monopoles.

* Rubbish. What 'two loudspeakers'? Ever heard of a horn loudspeaker?
... it produces longitudinal pressure waves.

Why then the two loudspeaker and the two monopoles have the same
directional patern?

* What 'two loudspeaker'? If you're drawing comparison between a
direct-radiator loudspeaker and a dipole and using that as a basis for
saying that EM waves are longitudinal, as I suspect you are, then you
should also consider a horn loudspeaker. Sound is radiated from the mouth
of a horn 'speaker and the other side of the compression driver diaphragm
can be totally enclosed. There is no simple comparison with a dipole
antenna in this case.




Also, antennas that radiate are fed with alternating current. The
terminal voltage is almost immaterial in comparison with the current -
that's what causes the radiation.

If you want to discover what radiates I suggest you read one of the
normal text books on the subject, like Kraus 'Antennas', and stop
making up your own versions!

To discower what radiates will be better to do experiments with tipping
of monopole antenas.

* Where do you get this stuff from? Please visit a library - you could
do yourself a lot of good.

Now Maxwell is avaiable on line. It is interesting to take a glance at
them.
S*

* It's even more interesting to read text books by writers such as Kraus
who have known provenance. Maxwell's equations are covered very well in
his books 'Antennas' and 'Electromagnetics' - I suggest you read them. It
appears a lot of what is published on the WWW is written by people who
haven't taken the time to learn the basic simple stuff; school pupils and
college students perhaps. You have to be very careful what you accept as
true when the internet is involved.

Take a rest in reading and look at the oryginal Hertz apparatus as the two
sources of longitudinal waves (radiated from ends). You should see the
Luxembourg effect (frequency doubling) and directional pattern.
S*