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This sheet of cheap “metamaterial” can be used to steer radar beams around.

From MIT Technology Review

Powerful radar, mostly limited to the military, could soon be cheap enough for cars and consumer drones to use.

Plenty of people play with small drone aircraft in their backyards these days. Tom Driscoll, cofounder and chief technology officer of a startup called Echodyne may be the only one whose quadcopter packs the kind of sophisticated radar used on fighter jets. “We flew it around, did some collision avoidance, and locked onto one of our engineers and followed him around my backyard,” says Driscoll.

Radar instruments that can be used that way are normally bulky and extremely expensive. Echodyne is working on a device that is compact and cheap enough to be used widely.

Radar systems work by sending out radio waves and using the echoes that bounce back to create an image of an object. Some radar systems use electronics to actively steer their outgoing radio waves, instead of just mechanically sweeping a beam in a fixed pattern. This lets them simultaneously scan the sky for objects and track specific ones with high accuracy. But the complex devices normally needed to steer radio waves around, known as phase shifters, make such electronically scanning radar expensive and bulky.

Driscoll’s drone carries an electronically scanning radar instrument that doesn’t have a conventional phase shifter. The outgoing radio waves are steered with a much simpler device, built using techniques borrowed from a relatively new area of research on what are known as metamaterials.

This drone has an advanced electronically scanning radar on board, equipment usually much too bulky and expensive for such small craft.

Metamaterials provide a way to get around many of the physical limitations that have previously defined how engineers could control radio, light, and sound waves. For example, while conventional lenses need their characteristic shape to bend light rays into focus, a metamaterial lens can bend light the same way while being perfectly flat.

Metamaterials are made from repeating structures that are smaller than the wavelength of the electromagnetic radiation being manipulated. Echodyne makes its metamaterials by tracing out repeating patterns of copper wiring on an ordinary circuit board.

A board with multiple layers of such wiring can direct radar beams. And applying different voltages to some parts of the wiring makes it possible to actively control the beam as a phase shifter would. “Any printed circuit board manufacturer could produce these,” says Driscoll.

The radar systems used by the military typically start at around $100,000, says Eben Frankenberg, CEO and another cofounder of Echodyne. He says his company hopes to mass produce compact radar systems that cost only hundreds or thousands of dollars.

Driscoll says that could make scanning radar become a standard sensor for vehicles and robots. Some prototype autonomous cars, including Google’s, use spinning laser sensors to watch the world around them in 3-D. That technique can map the world in very high resolution, but its range decreases in fog or snow. Radar doesn’t have that limitation, says Driscoll.

Echodyne also plans to offer its systems to the military, and to replace the radar already in use commercially: the spinning dishes seen on ferries and other boats that create simple maps by sweeping a beam around, for example, or the small fixed sensors in some cars that allow an adaptive cruise control system to keep a safe distance from the car ahead.

Echodyne was created by the patent licensing company Intellectual Ventures. In 2013, Intellectual Ventures set up a unit dedicated to building a portfolio of patents for metamaterials, and to figuring out how to commercialize them. Echodyne has also received investment funding from Microsoft cofounder Bill Gates, and venture capital firm Madrona Venture Group.

David Smith, a professor at Duke University who researches metamaterials and has worked with Intellectual Ventures, says that Echodyne’s approach provides very flexible ways to control radio waves. The company’s biggest challenge, he says, is to craft complete radar systems that can compete in the market. That means matching the performance of very high-end systems used by the military today to succeed in the defense market, and carefully controlling costs for applications in the car industry.

http://www.technologyreview.com/news/536341/metamaterial-radar-may-improve-car-and-drone-vision/