Advances in cloaking keep moving this field closer to reality. A team of researchers at Duke University have managed to make a small cylinder invisible to microwave radiation. Because this device doesn't reflect any of the microwaves, as other devices do, the illusion is perfect. The technique could be useful to the military for hiding objects that are transmitting microwaves and could also work to improve radio communications.
The researchers, Nathan Landy and David R. Smith, created a material, called a metamaterial, that bends long-wavelength light -- radio waves -- along its edges so that anything behind it is visible, but anything surrounded by it isn't. In 2006, Smith and his colleagues were among the first scientists to propose a theoretical cloaking device and then later that same year, built an imperfect invisiblity device.
In this latest work, Smith and Landy created a surface with tiny corrugations that bend the radio waves in such a way that when the waves hit an object, they are bent around it, rather than reflecting or getting absorbed. The technique makes the object invisible to microwave sensors.