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AUSTIN — Arthur C. Clarke once said that any sufficiently advanced technology would appear to humans as magic. Now, scientists are turning the tables and making magic into science.
Researchers at the University of Texas at Austin have succeeded in cloaking a 7-inch cylinder using relatively simple materials and methods. Though the object is still visible in natural light, it is invisible in the radio range of light. The researchers said it could be scaled to work in the visible range.
"Mantle cloaking has been proposed to realize ultralow-profile conformal covers that may achieve substantial camouflage, transparency and high-performance non-invasive near-field sensing," the report states. "Here, we realize and verify a mantle cloak for radio-waves."
It works by exploiting the effect of combining two materials in a fishnet pattern — extremely thin copper strips of tape combined with an extremely thin polycarbonate film, all woven together. Light travels along the cloak, and is eventually cancelled out, making it impossible to reach the observer's eye. Though the object remains, it's not possible to observe.
"When the scattered fields from the cloak and the object interfere, they cancel each other out and the overall effect is transparency and invisibility at all angles of observation," said study co-author Andrea Alu. The study was published this week in the New Journal of Physics.
Almost simultaneously, a study was published in the journal Applied Physics Letters showing similar cloaking abilities, but using ceramic dielectric materials rather than copper sheets.
Previous attempts at cloaking have relied on what are called metamaterials, synthetic materials designed with special properties. These artificially-engineered materials can't be found in nature. The two latest attempts have relied on combinations of normal materials. They are also much better at cloaking — more efficient and more transparent to the observing device. They're also much more flexible and thin.
"The advantages of the mantle cloaking over existing techniques are its conformability, ease of manufacturing and improved bandwidth," Alu said. "We have shown that you don't need a bulk metamaterial to cancel the scattering from an object — a simple patterned surface that is conformal to the object may be sufficient and, in many regards, even better than a bulk metamaterial."
Those involved in the research have said there could be important implications of such a mantle cloak in the law enforcement, biomedical and security industries.
