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Wimpie[_2_] · November 10th 14, 01:05 PM posted to rec.radio.amateur.antenna

El 10-11-14 0:32, escribiÃ³:
wrote:
El 09-11-14 23:01, escribiÃ³:
wrote:
El 08-11-14 8:03, escribiÃ³:
In rec.radio.amateur.antenna wrote:
"Brian wrote in message
...

His whole grasp of antenna theory is flawed.
He was trying to (indirectly) argue the other day via his his
interpretation of Maxwell's Equations you could generate an EM wave
by waving a magnet about. When corrected, he introduced another
variation.

Well, Brian, M3OSN, Old Chum, as was pointed out to you, all of your
posts these days are personal attacks aimed at one or another.

Why do you behave like that?

Certainly, as I corrected myself, if you wave a magnet about fast enough,
say, 1000,000,000 times per second, you will certainly generate an EM wave
and no-one has corrected me on that point because that point is true.

No, that point is utterly, completely, and absolutely false and goes
once again to show you have no clue as to the difference between an
electric field, a magnetic field, and an electromagnetic field.

Without doing the math, can we be sure that there is no radiation from
a rotating magnetic dipole?

You could ask someone who understands the math.

It is not that I don't understand the math, but I don't want to spend
time if we can get an answer by using reciprocity (the part of my text
you skipped).

Back to reciprocity:

When using reciprocity, a permament magnet will rotate in an EM
radiation field (produced by an antenna-transmitter combination, far
field distance). Of course you need to spin-up the magnet as you don't
have a rotating field. Once it is synchronized, you can extract power
from it (resulting in a slip angle).

So the other way around, using reciprocity, the rotating magnet will
generate power in a load connected to the antenna that was used to
generate the EM field.

None of which has a permanet magnet spinning in empty space, which is
why I snipped it.

If we can't prove that reciprocity (or other assumption) doesn't hold
for this case, then the rotating permanent magnet produces EM radiation.

And rigously proving any of that is much more complex then F=ma.

Jim, I would encourage you to dive into rotating magnetic dipole
radiation.

For practical electromechanical systems (even in practial vacuo) it is
negligible as (c0)^5 is in the denominator and (2*pi*rev/s)^4 is in
the numerator, but that doesn't mean it isn't present from a
theoretical point of view.

--
Wim
PA3DJS
Please remove abc first in case of PM

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