Nov 16 2012
Fractal Antenna Systems, Inc. today disclosed that it has successfully rendered a man invisible. The firm’s new invisibility cloak hid a subject named Peter at microwaves over a wide bandwidth at high fidelity. This is the first time any large object has been rendered invisible and the first time a person has disappeared from view using invisibility cloak technology.
Diagram showing size and arrangement of the world's first human invisibility cloak. (c) 2012 Fractal Antenna Systems, Inc. Source: Fractal Antenna Systems, Inc.
Invisibility cloaks differ from other types of stealth or camouflage by diverting waves around an object. The opposing side is visible but the object is not. They are unpowered and passively convey that view. A short video of the human invisibility cloak is available at: https://www.youtube.com/watch?v=Z_bj5NTnd_0 while additional explanatory video can be found at : https://www.youtube.com/watch?v=2BrVxpPYMiA
In August 2012, the firm completed and demonstrated the human-sized design to coincide with the issuance of the world’s first patent (USP 8,253,639) for an invisibility cloak, invented by the firm’s CEO, Nathan Cohen. Only the Cohen invisibility cloak has been recognized by the U.S. patent office as being new and novel and an actual device that can be realized.
Cohen is an expert in optics and imaging, with a Ph.D. in astrophysics from Cornell University. He holds 28 U.S. patents, including basic technologies in fractal antennas and fractal applications in electronics, real time deblurring in ultrasound, and a variety of other imaging related technologies.
Practical Fractals
The heart of the invisibility cloak is a close-spaced resonator arrangement made from almost 10,000 fractal shapes. Such shapes are built from simple patterns that are scaled. The human-sized cloak was configured as a large hollow cylinder with the cloak surrounding it as a thin shell. Subject Peter hunkered down inside to become hidden from microwave view, and thus realized a dream of countless generations--the quest to be invisible.
The human invisibility cloak technology was created with modest resources. “Hundreds of researchers worldwide, and likely close to a billion dollars, have been spent pursuing this scientific prize, otherwise unsuccessfully,” said Cohen. “With my team, we worked with a wealth of unique fractal-based knowledge, experience, and American innovation know-how. We got Jetson’s technology on a Flintstones’ budget.”
Boffin Beginnings And Other Cloaks
The general scientific concept of invisibility cloaks harps back to a theoretical study by British scientists Ward and Pendry in 1996. However, neither that study nor later follow ups presented a practical way to make invisibility cloaks. In 2009, Fractal Antenna Systems was the first and only research team to achieve cloaking at wide bandwidth at high fidelity, rendering true invisibility possible. The new human invisibility cloak hides far bigger objects, is three-dimensional, and has high fidelity over a large bandwidth. The device is not limited to working solely in one direction.
These attributes make it a unique and compelling example of a practical invisibility cloak realized, and the first of its kind.
A recent-diamond shaped ‘perfect cloak’ reported by other researchers has failed to achieve the results of the patented invisibility cloak. Commented Cohen: “If other approaches had been ‘perfected’ as claimed, then other researchers would have already cloaked a person. We are 200 times greater in bandwidth; a scaled factor of 10 thinner; and enclose at least 40,000 times bigger volume. There is no huge mirror contraption forming the outside. It’s like comparing a toy miniature Ferrari attached to a picture frame, to a real Ferrari.”
“The world’s top expert on radar has described the fractal invisibility cloak abilities as ‘an impressive first’ in the art of cloaking. Ultimately, fractals are why we succeeded and others failed. It is a testament to our ‘years ahead’ proprietary technology in fractal antennas that make such related, and difficult, problems solvable,” noted Cohen.
Uses and Demonstrations
Cohen stresses that the invisibility cloak technology was not designed specifically for stealth purposes. Cohen also believes infrared invisibility cloaks in large sizes are presently practical but large visible light versions will take more time. “Oddly, no one has yet to present a compelling reason to make a large visible light invisibility cloak, beyond the fact that it’s a nifty thing to do.”
Cohen’s team has already tested a thin, body-worn invisibility ‘vest’ successfully. Such a garment can be used to deflect dangerous waves, akin to the ‘deflector shields’ of science fiction.
In order to relax doubts about such an astonishing result, the firm has been presenting live invisibility cloak demonstrations since August, including ones at the Boxboro ARRL Convention (August 25), multiple IEEE-Boston meetings (October 25), and ones at the Radio Club of America (November 16), and Yale University (November 20). In addition, a peer-reviewed scholarly technical article has been accepted in the journal FRACTALS, and will be published in the coming weeks.
“Seeing is believing,” states Cohen.