"Szczepan Białek" wrote in message
...
"Richard Clark" wrote
...
I won't wait for that obvious failure. This is several steps above
your pay-grade. So, you should really attempt to work on first
principles rather than rummaging in the attic for impressive artifacts
of science.
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. 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. 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.
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, I'll
pass on what he wrote:
http://cer.ucsd.edu/~james/notes/MIT...diation%20Lab/
Chris