"christofire" wrote
...
"Szczepan Białek" wrote in message
...
And what should do Richard Harrison who wrote: "At the open circuited
ends of a resonant antenna there is almost double
the forward voltage but zero total current due to cancellation of the
dorward and reflected currents at the open circuit. At the open circuit
in the wire, all the energy in the wave is transferred to the electric
field. "
S*
What Richard wrote is correct, if written in a slightly provocative manner
(deliberately?). But he wasn't stating that the electric field 'At the
open-circuited ends of a resonant antenna' passes energy into a radiated
radio wave.
Look at this: ""At the open circuited ends of a resonant antenna there is
almost double the forward voltage".
"Almost double voltage" is like the pressure in the Kundt's tube.
The energy that makes it that far (i.e. isn't radiated on account of
current in the element) is stored temporarily in an 'electrostatic' field
which is one of several 'reactive' or 'induction' field components that
surround a dipole antenna and decay with distance much faster than the
radiation field components (i.e. those that make up a radio wave). As
I've noted before, the term 'electrostatic' should not be interpreted
literally as an unchanging field - it is used to differentiate between the
reactive components and the radiation components of electric field - if
this offends you, just call it a 'reactive' component of electric field.
This stored energy is passed back into the antenna during the following RF
quarter cycle.
And guess what ... one of the reactive field components is longitudinal!
... but it isn't part of a radio wave - both parts of a radio wave, the
magnetic field and the attendant electric field, are directed transverse
to the direction of propagation, but now I'm repeating myself from a week
or more ago. Power cannot be abstracted from the reactive fields,
including the longitudinal one; they affect the imaginary part of the
terminal impedance of the antenna.
Of course, I expect you will contradict all this but I still recommend
that you read a proper account of the fields around a dipole rather than
making up your own version.
It is not my version. The electrons were discovered 100 years ago.
Since you appear to have a phobia of libraries, you could buy a
second-hand copy of Kraus, Antennas for only $15 online:
http://www.abebooks.com/servlet/Sear...nnas&x=55&y=10
and there are many, many other sources.
I am sure that there is all about electrons. It is not easy to read with
understanding. Take a glance once more and try to find compressible
electrons.
Failing that, you could always search the web for a bootleg copy, or one
of the MIT Radiation Laboratory series of books. I don't condone
bootlegging but someone in another newsgroup recently gave a link to a
collection of illegal copies and, in the hope of ending these ridiculous
arguments,
All arguments are from this Group posts.
I'll pass on what he wrote:
http://cer.ucsd.edu/~james/notes/MIT...diation%20Lab/
S*