"Roy Lewallen" wrote in message
...
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.

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

Thanks Roy,

I appreciate that this is likely to be a protracted project and that
accurate measurements could be problematic to say the least. I intend to
examine the performance of a resonant dipole first, then non resonant dipole
elements and depending on results progress to more complex antennas. I am
fortunate enough to live very close to a surplus equipment supplier who has
a warehouse full of redundant commercial measurement equipment and
certification facilities, so I may become one of their more regular
customers. :-) I have more than enough qualifications to qualify for
membership of IEE and sundry other organisations so publication wouldn't be
a problem, but thanks very much for the kind offer.

I really am not interested in overturning current theory, I see this as an
opportunity of perhaps adding another aspect to it. Obviously any
'improvement' would have to match current results and enable enhanced
predictions to be of any practical use. I have spent well over 40 years
trying to understand how radio works. The wonder I felt as a child listening
to the radio and trying to understand how it could work has never
disappeared. Despite many courses, seminars and conversations with experts,
I still can't say that I really know how radio works.

As for religion, I attended a Jesuit run grammar school, put me off for
life. Needless to say, the main thing I learned was to question everything
and accept nothing at face value. So while it is true that current antenna
theory is good enough for all practical purposes, I think it is possible
that there may be room for improvement.

Regards
Mike G0ULI