gareth wrote:
"gareth" wrote in message
...
I get the impression that I am trying to maintain a discussion
with some whose knowledge and understanding is way below the
level at which I am discussing, and that it is their limited grasp
of technical matters that results in their infantile outbursts when
the shaky premises of their (almost religious) beliefs are
threatened.

This continues to be illustrated tonight. A changing electric
field produces a retarded changing magnetic field, and a changing
magnetic field produces a retarded changing electric field. One
cannot exist without the other, as demonstrated by Maxwell's Equations.

By that logic you could simply spin a permanent magnet and generate
an electromagnetic field, but you can't.

(And this is where the thinking behind the crossed field antenna was wrong,
because the changing electric field produced by the capacitor plates
produced the retarded changing magnetic field at all points in the same
space,
and it was unnecessary to introduced the (short antenna! (qv)) attempts
at producing the changing magnetic field.)

In the balanced transmission line, there are two travelling electromagnetic
waves out of phase with each other. Where some people are confused, and
their confusion gives way to infantile outbursts, is that the superposition
of the
two fields results in nearly total external field nullification resulting in
little, if no, radiation
and little, if no, near fields. However, both of the electromagnetic waves
continue
to exist and are guided by the two wires of the feeder.

Wrong.

In the case of coaxial feeders, the electromagnetic wave exists in the
dielectric.

Wrong.

(Let's not even get round to discussing slot antennae or dielectric
antennae, their
being no conductors in either case! :-) )

Wrong.






--
Jim Pennino

wrote in message
news

By that logic you could simply spin a permanent magnet and generate
an electromagnetic field, but you can't.


If you spin your permanent magnet at frequencies such that the
associated wavelength is a million metres, or thereabouts, then it
would be such a short antenna that there would not be enough radiation
from it to be detectable, (remeber that short antennae are poor radiators,
qv)

But, if you were to spin it at 1000 revs per sec (60,000 revs per minute)
then it would be a different matter.

How about attaching it to the cold side of a jet engine, and analysing
its radiation with your speccy, OM?

"gareth" wrote in message
...
wrote in message
news
By that logic you could simply spin a permanent magnet and generate
an electromagnetic field, but you can't.
If you spin your permanent magnet at frequencies such that the
associated wavelength is a million metres, or thereabouts, then it
would be such a short antenna that there would not be enough radiation
from it to be detectable, (remeber that short antennae are poor radiators,
qv)

But, if you were to spin it at 1000 revs per sec (60,000 revs per minute)
then it would be a different matter.

As I was driving away this morning, I realised that I'd typoed, and then
misled myself about
the possibilty of using a jet engine. Nobody's perfect!

I had meant o say to spin at 1000MHz, or 1,000,000 revs per sec, for the
example.

Apologies.

"gareth" wrote in message
...
"gareth" wrote in message
...
wrote in message
news
By that logic you could simply spin a permanent magnet and generate
an electromagnetic field, but you can't.
If you spin your permanent magnet at frequencies such that the
associated wavelength is a million metres, or thereabouts, then it
would be such a short antenna that there would not be enough radiation
from it to be detectable, (remeber that short antennae are poor
radiators, qv)

But, if you were to spin it at 1000 revs per sec (60,000 revs per minute)
then it would be a different matter.

As I was driving away this morning, I realised that I'd typoed, and then
misled myself about
the possibilty of using a jet engine. Nobody's perfect!

I had meant o say to spin at 1000MHz, or 1,000,000 revs per sec, for the
example.

For god's sake!!!! or 1,000,000,000 revs per sec!!!!!!!!!