Nathan “Chip” Cohen, W1YW, of Belmont, Massachusetts — the founder of Fractal Antenna Systems Inc and inventor of the fractal antenna — has been granted a patent for deflective electromagnetic shielding — essentially “cloaking” technology to defend against detection by radar and similar technologies.
“Ham radio experimentation can lead to some pretty cool innovations!” Cohen said in response to a recent QRZ forum post about the patent. “Let’s keep that spirit alive in 2018.”
The patent covers electromagnetic cloaking/deflection of, among other things, satellites, rockets, towers, antennas, vehicles, body coverings, ships, spacecraft, and even people.
“Much time and effort has been devoted to the quest for so-called invisibility machines,” the patent’s background information states. “Beyond science fiction, however, there has been little, if any, real progress toward this goal.”
According to the detailed description, the technology “provides one or more surfaces that act or function as shielding and/or cloaking surfaces for which at least a portion of the surface includes or is composed of ‘fractal cells’ (small fractal shapes, functioning as antennas or resonators) placed sufficiently close to one another, so that current present in one fractal cell is replicated or reproduced to an extent in an adjacent fractal cell. Without being limited by any theoretical explanation, surface plasmonic waves are believed to cause such replication in conjunction with evanescent waves.” The resulting surface would deflect around an object.
In terms of backscatter, upon which radar systems depend, Cohen has explained it this way: “The incoming wave reflects off a boundary condition at the object. Its reflection is out of phase and phase-cancels with the incoming wave. Bye-bye, backscatter.”
Fractal Antenna Systems first publicly demonstrated “person invisibility” in 2012 for a Radio Club of America audience. He also has demonstrated invisibility cloaks at Hamvention® and at the ARRL New England Division Convention. According to the company’s BusinessWire release, “Uses of the newly patented technology extend to commercial needs such as towers, antennas, people, and shielding, but it may also be used in defense and intelligence arenas.”
According to the BusinessWire release, the technology “produces the desired effects without any requirements on special orientation, composition, or shape of the object. The cloak/deflector can be very thin, and the effect can happen over a wide bandwidth.”
The company noted that “cloaking” applications concentrate on microwave and infrared wavelengths, “although the technology and patents apply to visible light as well.” Stated Cohen, “Cloaking at visible light has limited needs. Camouflage and projection methods are easier and cheaper at making something disappear to the eye. But at radio and heat wavelengths, the cloaking technology is an important enabler.”
Cohen, 62, applied for the patent in 2012. An ARRL Life Member and active DXer, he has been a radio amateur for more than 50 years.