A classic technology in many works of fiction is a tool to render a user invisible, and is often described as a cloak. When scientists actually learned how to make an object invisible with metamaterials though, 'cloak' would hardly describe the large devices. Researchers at the University of Toronto however have created a thin cloak that operates in a different way than the previous cloaks.
The first invisibility cloaks used metamaterials to cause light to bend in unnatural ways. As this requires special structures to achieve, the devices were somewhat large, and had to completely cover the object to work. This new cloak however uses a layer of antennas covering the object, which is considerably thinner. The antennas create an electromagnetic field that cancels out any light reflected off of the object. As it is only when light reflects off of an object that it can be seen, this renders the object invisible.
Currently the device has only been demonstrated with radio waves, but as the technology matures it should be able to work with light in other parts of the spectrum, including visible light. While the ability to make a target invisible would have an obvious military value, this cloaking technology could also be applied to remove obstacles that would otherwise block wireless signals.
Source: University of Toronto