On Fri, 20 May 2005 02:26:46 GMT, "Frank"
wrote:


"John Smith" wrote in message
...
Ham Op:

Yes, it is... mostly, people who are NOT gifted in explanations that the
"layman" can understand--gravitate to such extreme mathematics (and turn
them off, effectively silencing them).... let me give you my views...

I thought that my explanations were very non-mathematical, requiring only
minimal use of very simple calculations. My response was not complete as I
did not want to go overboard, but try to give very easy examples that could
be expanded on if any interest was shown. Perhaps you could be more
specific as to where I went wrong in my response. My mention of a couple of
textbooks was only to provide references for those interested in trying to
understand concepts in more detail. While it is true that some people are
capable of rigorous mathematical analysis, they cannot explain it in
non-mathematical terms. Those people, then, do not really understand their
subject.

So they can discover some knowledge and use it to make
products or predictions, but if they cannot explain it in
non-mathematical terms to your satisfaction, then, by your lights,
they do not understand it?

As a counter example, consider the comments of Richard
Feynman. When he was awarded a Nobel prize for his work in (I believe)
quantum electrodynamics, he was honored at a luncheon provided by the
faculty wives at his university. During the proceedings, he was asked,
"Doctor Feynman, could you let us know, in simple terms, what your
work was about?" He answered, "Madam, if I could explain it in simple
terms, they wouldn't have given me the Nobel prize for it." Will you
contend he didn't understand his subject?

In addition, you fail to understand that discovering knowledge
and teaching it are entirely separate gifts. Some who understand
deeply are incapable of teaching. Others, with less than complete
understanding, can teach effectively, while being incapable of coming
up with the knowledge in the first place.

One of our most poisonous (and arrogant) sayings is the one
which states, "Those who can, do; those who can't, teach." It's not
all that common to find people who can do both well.


It is also true that such complex subjects cannot be fully
understood without in-depth math (Which is something I wish I had).

Wherein you contradict yourself. You can't contend at the
samer time that a knowledge of mathematics on the part of the learner
is a necessity at the same time that you indict the one who can
explain only in mathematical terms for lack of understanding.

Heads or tails?

.
... it is somewhat obvious that when a wave sent forth from our antennas
encounters a metallic object that is close to resonate freq,

Not sure that resonance is important.
and a very good to EXCELLENT conductor, that a LARGE current flows in the
metallic structure encountered--

Current will flow in the surface.

what E and what H wave are then products are debatable (the energy
absorbed is re-radiated)--however--probably of a very different nature
than that of wave which encountered the metallic object in question--and
here is where this debate is ongoing...

If the conducting surface is perfect, no absorbtion takes place. The
reflected EM wave is planar, and identical to the incident plane wave --
with the exception of direction of propagation, and a phase reversal. A
(spatial) standing wave pattern is set up, and the analysis is identical to
that of a shorted transmission line.

at an extreme is a "tesla coil", ultimate voltage and virtually NO current
(very minimal current to generate the nice purple coronas)--yet an
excellent transmitting "antenna"--and that is ALL "E-wave." (well,
mostly...)

A Tesla coil is not an antenna, although some radiation will take place from
its conductors -- which will probably be damped sinusoidal pulses similar to
a spark transmitter. The radiation will not be all "E", but will have the
same E/H ratio of any radiated signal. i.e. E/H = 377 (ohms) in the far
field.

73,

Frank


Warmest regards,
John

"Ham op" wrote in message
...
Isn't Kraus "Electromagnetics" a little heavy on the math for the average
Ham ??

Frank wrote:

Hank, and Richard, For a good explanation of this subject I always liked
the book: "Introduction to Electromagnetic Fields" by Paul and Nasar.
The first two chapters of mathematical review are excellent. I see
barnesandnoble.com has the 3rd edition, used, for as low as $66. John
D. Kraus' book; "Electromagnetics" is also a very good text.

73,

Frank