Big Obstacle Disappears with Metamaterial Breakthrough

[Roger Bagula]

Big Obstacle Disappears with Metamaterial Breakthrough

By Business Wire
http://wireless.sys-con.com/node/895921


Fractal Antenna Systems, Inc., an antenna and electronics firm, today
demonstrated the first wideband, high fidelity performance from
metamaterials. Metamaterials are man-made structures that are built from
patterns of electronic resonators. The behavior of metamaterials can be
used to make light bend in the ‘wrong’ direction; enabling unusual
lenses and invisibility cloaks.

The firm solved a key problem limiting the practicality of
metamaterials—how to make them work at a large range of wavelengths.
Previous efforts by others had not succeeded, and had only shown
practical use at narrow bands, or single colours.

At its Open House today, the firm showed the world’s first wideband
see-through ‘invisibility cloak’. The invisibility cloak causes
microwaves to bend around an object to the other side and have close to
same intensity, as if there was no object at all. Noted Fractal’s CEO
Nathan Cohen: ”Previous researchers had measured this ‘through to the
other side’ cloaking at a narrow microwave frequency band. Ours is
better than ten times wider. By analogy, if this was visible light, the
entire spectrum of visible light would easily pass through, not just one
color. To our eyes, the cloaked object would not exist.”

Wideband behavior has been the main obstacle to making metamaterials, of
which cloaks are just one application, truly practical. Cohen believes
that many metamaterial applications are now rendered practical from a
scientific standpoint, and the remaining challenges are predominantly
those of manufacturability, cost, and identifying useful applications.
Cohen adds: ”We will be using our proprietary wideband metamaterial
technology to have some fun with cloaking, but don’t expect to cloak
Harry Potter soon. We’ve shown that’s its physically possible and
wideband metamaterials are reduced to practice. But we’ll pay somewhat
more attention to real needs of the marketplace in other applications at
microwave, IR, and visible light.”

[Roger Bagula]

http://www.businesswire.com/portal/site/google/?ndmViewId=news_view&newsId=20090415005076&newsLang=en
April 15, 2009 10:00 AM Eastern Daylight Time
Fractals Enable Wideband Invisibility Cloak

WALTHAM, Mass.--(BUSINESS WIRE)--Invisibility cloaks are the stuff of
wizards and alien starships. But on 27 March, 2009 Fractal Antenna
Systems, Inc. publicly demonstrated, in reality beyond the fantasy, the
first true ‘see thru’ invisibility cloak. Demonstrated with a prototype
device using microwaves instead of visible light, the cloak’s wide
bandwidth dramatically expands the capability of the new science of
metamaterials and renders another key example of the importance and
benefits of fractals in electronics and sensors technology.

Led by physicist Nathan Cohen, the firm’s team wanted to solve a
problem: how to make metamaterials practical by expanding their
bandwidth capabilities. Metamaterials are exotic, crazy quilt-like
collections of tiny resonators. Without wide bandwidths, however,
metamaterials have very limited practical use. Previous efforts, such as
with cloaks and lenses, only demonstrated useful metamaterial behavior
in the narrowest frequency or color bands,“like playing a song on a
piano with only one key,” noted Cohen. “We’re playing music with the
full keyboard.”

Using fractals, geometric shapes that are built up from multiple scaling
of a simple pattern, the team showed that metamaterials can now be
enabled over a far greater bandwidth. “We are the world’s experts in
fractals,” notes Cohen, who himself invented fractal resonators and
showed a basic property of widebandedness with fractals in the famous
Maxwell’s equation. “So it was natural for us to use our patented,
proprietary technology to build a metamaterial cloak, one that works far
beyond the tiny bandwidths already reported.”

The firm’s cloak is a simple looking device packed with fractal
technology. Built from belts of circuit boards festooned with fractal
resonators, these belts slip the microwaves around the cloaked object so
the object is effectively invisible and “see thru”. The observer sees
the original image or signal, without it being blocked by the cloaked
object. Using no power, the fractal cloak replicates the original signal
(that is, the signal before blocking) with great fidelity from 500 MHz
to almost 1500 MHz. Engineers refer to this as a “3:1” bandwidth.

“While we had to show this by working at microwaves, physicists
especially are excited by this result, in part because it means there is
now a path and a recipe to reaping the benefits at visible light, which
is a 2:1 bandwidth. So nature has shown us, through the use of fractals,
that you have the science to cloak at the full spectrum of colors at
visible light,” said Cohen.

The much celebrated previous efforts on metamaterial cloaks by a Duke
University-based international team had failed to demonstrate ‘see thru’
cloaking beyond a narrow band, and in a recent update, had abandoned the
‘see thru’ approach altogether, using a ‘mirror cloak’ instead. “I guess
it’s cloaking, in the sense that it ‘conceals’, but in my opinion, fans
of Harry Potter might not accept it. People equate ‘cloak’ with
‘see-thru’. Using a mirror-like camouflage is a form of cloaking, but I
believe it’s hard to see why that’s new or important. In contrast we
have the real deal,” said Cohen. “To use an appropriate pun, our results
are transparent.”

Cohen notes that the obstacles to making wideband visible light cloaks
with metamaterials are daunting. “You won’t see it soon. The technology
to make the stuff doesn’t exist. Maybe if you want to cloak a pin-head
sized object, but not to do a ‘see thru’ one of Harry. I would be very
skeptical of scientists who predict this is happening in a few weeks or
months.”

Despite the obstacles, Cohen and his team will be leveraging the results
of the cloak study to make products of wideband metamaterial for devices
in addition to cloaks. “It’s an important new tool in our toolbox, a
natural extension of our vast experience in fractal antennas and related
technologies. There lies the excitement for us. We now can say
metamaterials won’t have a disappearing act in the history of new
technologies.”

ABOUT THE CLOAK AND FRACTAL ANTENNA SYSTEMS, INC.

To aid in the understanding of the new cloak, Fractal Antenna Systems,
Inc. has devoted an exclusive website, www.metacloak.net.

Fractal Antenna Systems supplies products for the world’s most demanding
wireless, and electromagnetic applications. Backed by twenty four U.S.,
and international patents, plus numerous patents pending, Fractal
Antenna Systems is the recognized pioneer in fractal technology, with
extensive research and field experience. The company is a privately held
and headquartered in Waltham, Massachusetts, USA.