This website uses cookies primarily for visitor analytics. Certain pages will ask you to fill in contact details to receive additional information. On these pages you have the option of having the site log your details for future visits. Indicating you want the site to remember your details will place a cookie on your device. To view our full cookie policy, please click here. You can also view it at any time by going to our Contact Us page.

Metamaterial lens focuses radio waves with extreme precision

15 November 2012

Metamaterials, with their intricately designed structures, are capable of bending electromagnetic waves in ways that are impossible for materials found in nature.

The orientation of 4,000 S-shaped units forms a metamaterial lens that focuses radio waves with extreme precision, and very little energy lost (photo: Dylan Erb)

Scientists are investigating metamaterials for their potential to engineer invisibility cloaks — materials that refract light to hide an object in plain sight — and 'super lenses' which focus light beyond the range of optical microscopes to image objects at nanoscale detail.

Researchers at MIT have now fabricated a three-dimensional, lightweight metamaterial lens that focuses radio waves with extreme precision. The concave lens exhibits a property called negative refraction, bending electromagnetic waves — in this case, radio waves — in exactly the opposite sense from which a normal concave lens would work. 

Concave lenses typically radiate radio waves like spokes from a wheel. In this new metamaterial lens, however, radio waves converge, focusing on a single, precise point — a property impossible to replicate in natural materials

A metamaterial’s extraordinary properties are determined largely by its structure, similar to how a diamond’s crystals impart strength. A material can refract light differently depending on the shape of individual units within a material, and the arrangement of those units as a whole. 

The MIT team has come up with a blocky, S-shaped 'unit cell' whose shape refracts radio waves in particular directions. This unit shape is used as the basis for the concave lens, the rough shape being created from more than 4,000 unit cells, each only a few millimeters wide. 

3-D printing was used to build a lens layer by layer from a polymer solution, each layer being subsequently coated with a fine mist of copper to give the lens a conductive surface. 

To test the lens, the researchers placed the device between two radio antennas and measured the energy transmitted through it. Most of the energy was able to travel through the lens, with very little lost within the metamaterial — a significant improvement in energy efficiency when compared with past negative-refraction designs. The team also found that radio waves converged in front of the lens at a very specific point, creating a tight, focused beam. 

The device, which weighs less than a pound, may be used to focus radio waves precisely on molecules to create high-resolution images — images that are currently produced using bulky, heavy and expensive lenses. Such a lightweight device could also be mounted on satellites to image stars and other celestial bodies in space.


Contact Details and Archive...

Print this page | E-mail this page