NEC-LIST: Letter from Grimes

Dear Colleague,
 
The following letter from Prof. Grimes was sent to me and a few other nec
participants. It was also sent to the nec list but since it has attachments
I was told that it did not reach that list. The attachments are
 
Dale M. Grimes and Craig A. G, "Minimum Q of Electrically Small Antennas: A
Critical Review, Microwave and Optical Technology Letters, vol. 28, No. 3,
Feb. 5 2001, pp. 172-177.
 
Dale M. Grimes, "Radiation Q of dipole-generated fields," Radio Science,
vol.34, No.2,pp.281-296, March-April 1999.
 
For your information, here is the letter.
 
Gentlemen

Collin's paper attacks a Grimes and Grimes work, the JEWA paper, which we
had pointed out in a subsequent 1999 Radio Science paper was incorrect.
Since the Editor handling Collin's paper never contacted us about his work
(nor allowed a rebuttal) what is left is Collin's trashing of a paper we had
already said, in print in a widely read journal, was wrong.

The JEWA paper uses frequency domain analysis which is fine for some
specific antenna designs, albeit common ones, but is not a general technique
suitable for all radiation sources. This is fact. For a general antenna
design time domain analysis must be used. The reason is simple enough,
information is lost in the frequency domain that is not in the time domain.
No one, to our knowledge, has found any errors in the time domain results
initially presented in the Radio Science paper attached, placed in
perspective in the Q review paper attached (which summarizes the issue of Q,
it's determination, and where Collin's errors are pointed out for the reader
to which Collin has made no response), and tied together from an
electromagnetics perspective (with an improved technique) in the recent book
The Electromagnetic Origin of Quantum Theory and Light published by World
Scientific. We also gave an hour lecture on this at the recent PIERS
conference, the slides of which are downloadable from

http://www.ee.psu.edu/grimes/publications/

Our point is simple: Determination of radiation Q in mixed modal fields
requires use of the time domain. The frequency domain is only correct with
certain limited radiating structures due to missing phase information. When
one does the general, complete math correctly a considerable amount of
insight into physical phenomena regarding electromagnetic emission and
quantum theory becomes clear. Whether that means we can build a zero-Q
antenna is an open question, certainly mother nature can.... atoms support
wavelength to size ratios of hundreds to thousands yet apparently don't have
any problems with reactive energy storage.

Why don't you guys read the papers and do the math. A proofs a proof, if
the math is wrong we would be delighted to know about it. If the math is
correct then I suggest the EM community might be well advised to consider
the consequences of it.

I would also suggest if you approach the results of our experimental work
without bias you might find something interesting going on there. While
such an antenna is not going to be sold commercially in the near future
there are clues there for people interested in this field and have the time
and resources to pursue it.

Respectively, Craig Grimes
 
 
 
Edward E. Altshuler
Sensors Directorate
Electromagnetics Technology Division
80 Scott Drive
Hanscom AFB, MA 01731-2909
(781)377-4662
(781)377-1074 Fax
 

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