3D cloak is first to work in free space

Published in Physics World, 8 Aug 2011

Physicists in the US claim to have created the first 3D invisibility cloak that can operate alone in free space. The cloak, based on a “plasmonic” shell, can hide a cigar-sized cylinder from microwaves – although it currently only operates for one microwave polarization.

Invisibility cloaks have been around since 2006, when a team led by David Smith at Duke University in North Carolina, US, produced a device that could guide microwaves of a very narrow frequency around an area a few centimetres in diameter. The device was based on a “metamaterial” comprising an array of resonators that altered the electrical permittivity and magnetic permeability throughout the cloak. Variations in these properties resulted in the microwaves bending round the hidden space like water around a stone, albeit only in 2D. […]

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