Scientists have created a microwave invisibility cloak

U.S. scientists have created a cloak of invisibility from a set of plasmonic resonators, which first allows you to hide from detection in the microwave spectrum of three-dimensional objects of any shape.

This is stated in an article published in New Journal of Physics, RIA Novosti reported.
In recent years, physicists have created a multitude of devices, allowing to make objects invisible in a certain range of the radiation. Typically, the functionality of these coats of stealth is extremely limited - some of them only know how to hide the two-dimensional objects, while others work only with a limited viewing angle and is strictly a given temperature. As a rule, partial invisibility provided by the properties of so-called metamaterials - exotic compounds with special optical properties.
A team led by Andrea Alu of the University of Texas at Austin (USA ) has developed a microwave invisibility cloak based on another technology - the plasmonic resonators, which allows this device to operate at any angle of view and any position without loss of efficiency.
Thin strips of some metals - for example, copper, gold or silver - are able to absorb visible light and pass it on in the form of heat or other forms of electromagnetic radiation. This is because on the surface of the metal having the so-called plasmons - collective oscillations of electrons that can absorb and emit energy in the form of light waves.

Alou and his colleagues have adapted these features to create plasmonic metamaterials with special reflective and refractive properties. According to scientists, they were able to adjust the properties of his cloak so that it ... This leads to their mutual destruction, which hides an object from detection in this part of the spectrum.
Physicists have used a prototype of his invention to hide a small plastic cylinder. In general, the results of the coat matched the expectations of researchers - the zone of maximum suppression of the scattered radiation was in the area between 2.7 GHz and 3.8 GHz and reached its peak at a frequency of 3.1 GHz.
Our observations showed that the quality of invisibility was the same for any angle of observation and at any distance between the object and the cloak, which he hid.
Scientists believe that a similar technique can be used to develop a device that hides objects of arbitrary shape from the rays of visible light.
... On the other hand, the maximum size of objects depends on the frequency of the cloak, and therefore the optical cloaks will work only for micrometer -sized objects. However, even this can be used in practice - we are exploring the possibility to hide the sting of the electron microscope in the optical range. This can improve the accuracy of the biological and optical measurements, ...