Canadian researchers create thin radar invisibility cloak

U of T researchers new approach to cloaking surrounds an object with small antennas that collectively radiate an electromagnetic field and cancels out any waves scattering off the cloaked object. (Credit: University of Toronto)

Designed by Professor George Eleftheriades and PhD student Michael Selvanayagam, the cloaking system works by surrounding an object with small antennas that collectively radiate an electromagnetic field away from the object, and thereby cancel out any radio waves scattering off the cloaked object.

While their experimental demonstration cloaked a metal cylinder from radio waves using one layer of loop antennas, they say the system can be scaled up to cloak larger objects using more loops. In addition, Eleftheriades says the loops could become printed and flat, like a blanket or skin.

Currently the antenna loops must be manually attuned to the electromagnetic frequency they need to cancel, but in future they could function both as sensors and active antennas, adjusting to different waves in real time, much like the technology behind noise-cancelling headphones.

Beyond hiding military vehicles, the researchers say the cloaking technology could be used to eliminate signal-blocking structures around cellular base stations or alter the signature of a cloaked object, making it appear bigger, smaller, or even shifting it in space.

While effective with radio waves, Eleftheriades says the same antenna principle could used to work with Terahertz (T-rays) or light waves as the necessary antenna technology matures.

“There are more applications for radio than for light,” says Eleftheriades. “It’s just a matter of technology—you can use the same principle for light, and the corresponding antenna technology is a very hot area of research.”
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