On Sun, 07 Sep 2003 15:29:55 GMT, Paul Victor Birke
wrote:

This is a very good question!!

Unfortunately for such a good question, the answer reveals a mediocre
reality compared to the glowing claims.


Why couldn't we have a big rubbery fractal that folded up so to say.

Proximity often leads to increasing loss, and rarely opportunity for
boundless gain.

They have them stuck inside the unit and you have your hand wrapped
around the antenna-not such a good idea since you are conducting, at
least partially, and therefore shielding the inside antenna.

Quite so, but hardly the fault of the antenna and has nothing to do
with any perceived characteristic.

Why not make it in a rubber matrix and be about 2" * 4" folding up.
That would be goog for added sensitivity I would strongly suspect.

Paul Birke (EE)

Hi Paul,

Soothe your suspicions. A randomly crushed antenna is just as
effective. However "just as effective" means equally in-effective.


totojepast wrote:

According to the July 1999 issue of Scientific American (available
online at

http://www.sciam.com/article.cfm?art...B7809EC588F2D7),
Motorola started using the fractal antennas inside its cellphones. Do
they still use them? And what about the other manufacturers?

They could. Some manufacturers sell antennas complete with resistors
for their own novel characteristics. Some cellphone users paste in a
foil do-dad sold at two for $19.95 on TV too (never mind that a piece
of aluminum foil works just as well for a penny's worth of material
and no shipping/handling fee).

"(....) Cohen, who founded Fractal Antenna Systems four years ago, is
now working with T&M Antennas, which makes cellular phone antennas for
Motorola. T&M engineer John Chenoweth says that the fractal antennas
are 25 percent more efficient than the rubbery "stubby" found on most
phones. (...)

They could also claim to be 55% more efficient than a resistor too.

Just why these fractal antennas work so well was answered in part in
the March issue of the journal Fractals. Cohen and his colleague
Robert Hohlfeld proved mathematically that for an antenna to work
equally well at all frequencies, it must satisfy two criteria. It must
be symmetrical about a point. And it must be self-similar, having the
same basic appearance at every scale--that is, it has to be fractal."


Others, who were not employed selling fractals have proven
mathematically that they are not. Now, if you replace antennas with
cigarettes and mathematics with reports on cancer, guess what clash of
reports you would find there. A simple review into the quality of
science of fractals "antenna research" reveals not very much range nor
depth. Most announcements are repetition of unique examples that you
will never find in that cellphone.

As one poster pointed out YEARS ago, was that if fractals were such a
good idea, we would all have replaced our antennas with them by now.

This, of course, has lead one fractal proponent to simply declare that
all the antennas we do use today, are already fractal! This oddball
of recursive thought leads us to then ask, what merit is there in your
particular kind? That's where you get into math 4 places to the right
of the decimal for complex geometries that could only begin to make
economic sense in the GHz frequencies (if you cared). Anyone could as
easily make the same claims for the unique color of ink in their sales
brochures giving boosted performance.

73's
Richard Clark, KB7QHC