Microwaves being sent at the cloaked cylinder
A team of UT researchers have developed an ultrathin cloak that can make an object undetectable to radar. They say it could be used by the U.S. military to aid in national defense.
UT researchers have created an ultrathin invisibility cloak for objects that can make them undetectable to radar scanners, technology they say could be used throughout the branches of our nation’s military.
Andrea Alu, assistant professor of electrical and computer engineering, and his team of researchers said the cloak can hide three-dimensional objects from microwaves in any direction. The group presented a study March 26 that was published in the New Journal of Physics, describing their use of an ultrathin layer called a “metascreen” used to cloak an 18-cm cylindrical rod.
While it will not make objects or humans physically invisible, the cloaking technology will render the object underneath it nearly invisible to radar detection. The process, called “mantle cloaking,” uses thin strips of copper tape attached to a flexible polycarbonate film just micrometers thick.
Research Associate David Rainwater, who is a part of Alu’s research team, said waves bouncing off the surface of an object are essentially what is detectable. He said the cloaking technology creates an opposite effect, distorting the waves and causing them to pass through the object rather than bouncing off.
“The cloak makes the object unable to reflect microwaves and creates an opposite scattering effect,” Rainwater said. “The two different reflections cancel each other out.”
Rainwater said Alu’s team of researchers has been studying cloaking since 2005, but first created the technology last year, when they became the first to successfully make a three-dimensional object invisible to microwaves using a method known as “plasmonic cloaking.” He called the team’s first cloak “ugly and bulky,” saying the new technology is much thinner and doesn’t interfere with the size or shape of the cylinder. He said the new cloaking technology is much easier to create and use.
“The idea is that you can essentially use the same technology as circuit board printing to create the cloaks,” Research Associate Aaron Kerkhoff, who is also a part of Alu’s team, said. “The materials used are very basic. No exotic materials or technology are required to create the cloak.”
Rainwater said the research team chose to cloak objects using microwaves due to the potential defense applications of the cloaking technology.
“It could be used for essentially anything the U.S. Department of Defense wants to make undetectable by radar,” Rainwater said.
He cited the ability to cloak the antennas on ships that have more than one, to stop them from interfering with each other, as one of many uses the technology could have.
Rainwater said while similar technology could one day possibly be used to make very small objects, up to roughly a centimeter in length, invisible to the naked eye by masking them from light waves, it is unlikely that such technology will ever be available for larger objects.
“The object has to be about the same size as the wave,” Rainwater said. “Microwaves are slightly longer than the cylinders we’re cloaking, but light waves are very small. Cloaking light waves to make objects physically invisible would require very small, almost microscopic, objects, like medical probes used for imaging.”
After successfully cloaking the small cylinder, the team is moving on to larger and more complex objects with multiple frequencies for radar cloaking and increased antenna performance.