On 15 Nov, 16:13, Roy Lewallen wrote:
Mike Kaliski wrote:

Hi Roy,

He does mention that antennas possess radiation resistance, not to be
confused with and not the same as, characteristic impedence (or
feedpoint impedence) and that the characteristic impedence will vary
along an antennas length.

As for the actual point(s) along an element at which an antenna radiates
(transfers energy to free space) with maximum efficiency, he makes no
comment.

I seriously doubt that there is anything in the article that you would
dispute.

It seems that everyone was so busy laughing on this newsgroup, that no
one has actually provided any information as to whether any detailed
research has ever been carried out as to what is going on within the
radiating elements of an antenna. There is loads of theory in the text
books, but I have yet to see any empirical measurements or results.

If you haven't seen any measurements or results, you haven't looked in
any of the professional publications over the past hundred years or so.
There have been a great number of measurements of antennas made. Of
those, none to my knowledge have ever definitively shown results other
than the textbook theory predicts. That's pretty good confirmation of
the current theory.

If there is merit to alternative theories, they should predict exactly
(or at least within the most precise measurement capabilities we have)
the same results as the current textbook theories, because those
theories agree closely with measurement. That means the alternative
theories must come with equations which can be used to predict antenna
performance as well as what we use now with great success. Vague
hand-waving is adequate to convince a certain number of rraa readers,
but it doesn't go far with those of us who actually design antennas that
have to work.

. . .
I may have submitted the post, tongue in cheek, to stir things up a bit,
but on reflection there seems to be something of merit in the idea. I am
revisiting the appropriate chapters in Kraus and Terman to see where the
error in my logic is. In the absence of any direct evidence of
contradiction, I think it may be worth developing this idea and making a
few measurements of my own to see what the truth of the matter is.

There's a real problem here. Making even half decent measurements of
antennas is an extremely difficult undertaking. People without the
proper equipment, experience, and knowledge of tolerances to be expected
frequently make poor measurements and draw erroneous conclusions from
them. Before you get too involved, I suggest starting with a dipole,
loop, or some other very simple, well understood, and well documented
antenna and see just how good your measurement methods are. If you can't
do those simple antennas properly, then any other measurements you make
shouldn't be trusted. And those are the easiest ones. If you want a real
challenge, try a very short antenna. Just keeping the feedline from
being part of the system can be a nearly insurmountable task, and
measuring a very small resistance in the presence of a very large
reactance isn't easy either. Unless you can deal with these and other
measurement realities, your measurements might be fun, but they won't
mean anything. You can publish on rraa and draw a certain number of oohs
and ahs, but it won't be material for the IEE or IEEE -- not because
they're contradicting conventional theory, but because they're not
representative of reality.

Oh my, you sound so upset.
Your theory used in Eznec was designed
around known "reality" because you found the need to add the proviso
that there was a sino soidal current at all points on the radiator.
Number one, it is not legitamate to add a proviso or a special
condition
to a known law.( Electrical or Mechanical)
Number two It becomes a worse problem when the proviso added is in
error.
Number three, You should not retain a proviso if it proves incorrect .
The fact that present theory has passed the test of time means
nothing.
The threat of retaliation trumps science when humans are concerned.
Gallilao never saw the day that the earth was proven round which
stood the test for a very very long time.
But you could explain to the world how a sino soidal current passes
thru
a distributed capacitance and still retain its properties as it
encounters every segment. This is per the proviso you have placed
with
existing Maxwell's laws with respect to your computor program.
But no you can't! Until then I don't think you are equipped to say
that written theory can be taken as fact.Especially when known laws
are twisted so you can gyrate your program to known reality.
The old saying still stands, Garbage in will produce garbage out
unless the outputs are subject to reprocessing !

Art Unwin...KB9MZ






Amateur radio is supposed to be a learning experience, right? And you
can't learn without making mistakes. After 40 years of following the
diktats of professional communications and electronic theory, I think
the time is right to kick off the traces and challenge some of the
accepted authodoxies. I do know all the conventional stuff, it just
doesn't satisfy my soul.

Have you considered religion? The rules of evidence are much more
relaxed in that environment, so alternative theories are more readily
accepted. Just look at the proliferation of denominations. There's
always room for a few more.

You probably know more about antennas than anyone has a right to know
Roy, but it's a strange universe out there and it's just possible that
there's a few more things to learn yet.

Indeed there are. When you have an alternative theory that agrees as
closely with measured results as the current ones, and which can be used
to predict antenna performance, I'd like to be among the first to read
your paper and benefit. Shoot, I might even incorporate the equations
into EZNEC to make it even more accurate than it is now. I'm a member of
the IEEE Antennas and Propagation, Broadcast, and EMC societies, so I'll
see any papers published in those journals. And I can easily get papers
published by the IEE or other societies. Have at it!

Roy Lewallen, W7EL- Hide quoted text -

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