Microwave Invisibility Cloak Conceals 3D Objects

A paper published in the January 25 issue of the New Journal of Physics describes a tube-like structure that is capable of masking three-dimensional objects from microwave light. This invisibility cloak is one of the few out there that is capable of hiding 3D objects from view.

The tube itself is made up of insulating materials that are laced with long strips of copper. While they do not obscure the objects within from view in optical wavelengths, they are very efficient at hiding them in microwave wavelengths. The device could have important military applications.

University of Texas in Austin (UTA) investigators say that this is the first time when an invisibility cloak is capable of hiding objects in three dimensions. Previously, such devices could only conceal 2D objects, by diverting light around the structures.

In 2011, scientists were able to produce a cloak that could hide bumps on a surface. Now, the full-3D version of the same device has just been completed. Interestingly, the device does not have reflective surfaces or specialized microwave chambers built into its surface.

The team's secret is an artificial metamaterial, a structure that is built specifically for this application. Its special abilities kick into gear when the object concealed inside the cloak is hit by microwaves, and then starts to reflect them back.

This is the process through which objects become visible, regardless of wavelength. But the special materials the cloak is made of can reflect electromagnetic waves in such a way that the waves reflected by the target object are canceled out.

“We don't need mirrors, we don't need waveguides, we just built a cloak with a cover around an object,” says UTA engineers Andrea Alù, who was also the leader of the new investigation. The cylinder the team built was around 18 centimeters (7 inches) long.

At this point, investigators around the work are striving on the Holy Grail of metamaterial research, which is developing an invisibility cloak that is capable of concealing objects at optical wavelengths.

Such a technology would have numerous applications, in fields ranging from medicine to war technologies. Alù's team is working on a 3D cloak for microscopic objects right now, Innovation News Daily reports.