"Chuck...K1KW" wrote in message news:0wNvc.39192$3x.31853@attbi_s54...
Anyone know anything about the "technology" in the article below?

http://www.uri.edu/news/releases/?id=2659

Chuck...K1KW

Smaller antenna design said to boost efficiency
By R. Colin Johnson
EE Times
June 07, 2004 (4:00 PM EDT)



PORTLAND, Ore. — A four-year skunk works effort at the
University of Rhode Island in Kingston has cut the size
of an antenna by as much as one-third for any frequency
from the KHz to the GHz range.
Using conventional components the four-part antenna
design cancels out normal inductive loading, thereby
linearizing the energy radiation along its mast and
enabling the smaller size.
"The DLM [distributed load monopole] antenna is based on
a lot of things that currently exist," said the
researcher who invented the smaller antenna, Robert
Vincent of the university's physics department, "but
I've been able to put a combination of them together to
create a revolutionary way of building antennas. It uses
basically a helix plus a load coil."
The patent-pending design could transform every
antenna-from the GHz models for cell phones to the
giant, KHz AM antennas that stud the high ground of
metropolitan areas-Vincent said.
For cellphones, for example, Vincent said he has a
completely planar design that is less than a third the
size of today's cellphone antennas. And those 300-foot
tall antennas for the 900-KHz AM band that dominate
skylines would have to be only 80 feet high, with no
compromise in performance, using Vincent's design, he
said.
"With my technique, I reduce the inductive loading that
is normally required to resonate the antenna by as much
as 75 percent . . . by utilizing the distributed
capacitance around the antenna," he explained.
"I looked at all the different approaches used to make
antennas smaller, and there seemed to be good and bad
aspects" to each, Vincent said. "A helix antenna is
normally known to be a core radiator, because the
current profile drops off rapidly; they are just an
inductor, and inductance does not like to see changes in
current, so it's going to buck that.
"What I found was that for any smaller antenna, if you
place a load coil in the middle you can normalize and
make the current through the helix unity; that is, you
can maximize it and linearize it," he added.
Vincent has verified designs from 1.8 MHz to 200 MHz by
measuring and characterizing the behavior of his DLM
antenna compared with a normal quarter-wave antenna of
the same frequency. He found that many of the
disadvantages of traditional antennas were not problems
for the much lighter inductive loading in a DLM.
To check his theory, Vincent analyzed and compared the
current profiles, output power and a score of other
standard tests for measuring antenna performance. All
measurements were in reference to comparative
measurements made on a quarter-wave vertical antenna for
the same frequency, on the same ground system and same
power input.
"I was able to increase the current profile of the
antenna over a quarter-wave by as much as two to 2.5
times," said Vincent.
"The technology is completely scalable: Take the
component values and divide them by two, and you get
twice the frequency; take all the component values and
multiply them by two, and you are at half the
frequency," said Vincent.
Vincent said he is moving up into the GHz bands for use
with cellphones and radio-frequency ID equipment. A
problem in the past has been that as components are
downsized, they become too small to utilize standard
antenna materials. At 1 GHz, for example, the helix is
only eight-thousandths of an inch in diameter and
requires more than 100 turns of wire.
"So I came up with a new way of developing a helix for
high frequencies that is a fully planar design; it's a
two-dimensional helix," said Vincent.
With the new helix design, Vincent has built a prototype
7-GHz antenna that he claims is indistinguishable from a
quarter-wave antenna in all but its size. "Because the
new design is completely planar, we could crank these
out using thin-film technologies," Vincent said.