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December 11th 03, 08:45 PM

(Art Unwin KB9MZ) wrote in message m...

Peter, the ham community is full of people who know it all each
with their own followers that tailgate and throw barbs.
When Chip came up with Fractals he shared it on this newsgroup...

There is some dispute whether Cohen "came up" with Fractals.

Some history from http://www.tsc.upc.es/eef/:

Background

1940's. L.J.Chu and H.Wheeler stablish a fundamental limit on the
performance of small antennas.

1960's. Several research teams at the University of Illinois at
Urbana-Champaign, University of California and Ohio State University
introduce the concept of frequency-independent antennas. The
self-scaling concept gives place to the log-periodic dipole array and
to the spiral antennas.

1970's. B. Mandelbrot coins the term 'Fractal'. Such a name is used to
describe a family of geometrical objects that defy the traditional
rules of the Euclidean geometry. Later on, Mandelbrot states that such
a weird fractal shapes are, in fact, among the most common forms in
nature.

1980's. D.Jaggard et al. coin the term 'Fractal Electrodynamics'.
Electromagnetics and Fractal Geometry blend into a novel discipline.
The interaction of fractal bodies and electromagnetic waves are
investigated and some relationships between common fractal properties
and the scattered electromagnetic waves are established.

1990's. The first reported fractal multiband antennas are introduced
by C.Puente et al. from the Universitat Politècnica de Catalunya.
Also, the potentiallity of fractals to become small antennas is
introduced by the same research team and by N.Cohen from the
University of Boston.

Some Significant Milestones

1986-1993. Several authors theoretically investigate the
relationships between fractal arrays and their array factors. Some
fractal and array properties such as Fractal Dimension and Secondary
Lobe Ratio are linked for the first time.
1993, November. The potentiallity of fractal arrays to become
multifrequency arrays is introduced by C.Puente at the University of
Illinois at Urbana-Champaign during a graduate course discussion.

1994. Some prelimar ideas on multiband fractal arrays are presented by
C.Puente at an URSI meeting in Las Palmas, Gran Canaria, Spain.
Further work on such ideas gives place to a paper that is submitted to
the IEEE Transactions on Antennas and Propagation in May 1994, and
published in May 1996.

1995, May. After several months working on the invention of the
Sierpinski antenna, the Universitat Politècnica de Catalunya finally
applies for the patent on Fractal and Multifractal Antennas . Such
results proved the feasibility of fractals to become multiband
antennas (i.e., antennas that keep the same parameters at several
frequency bands). A paper reporting the first results is submitted to
IEE Electronics Letters.

1995, Summer. Some preliminar ideas on fractal small antennas are
suggested by N.Cohen from the Boston University.

1996-1998. The first reported experimental results on fractal
multiband antennas are published by the Electromagnetics & Photonics
Engineering research team from the Universitat Politècnica de
Catalunya.

1998. The Koch monopole becomes the first reported fractal small
antenna that improves the features of some classical antennas in terms
of bandwidth, resonance frequency and radiation resistance. Whether
such antennas are bounded to the fundamental limits on small antennas
is still a topic under investigation.

1998. The Fractal Team from the Electromagnetics & Photonics
Engineering group (UPC), in cooperation with FractusTM the Fractal
AntennasTM company from the Sistemas Radiantes F.Moyano S.A. group,
develope the first commercial multiband fractal shape antennas for GSM
+ DCS cellular phone systems.