Dawn of the drone age

Low-power radar could help bring on flying cars and drone deliveries

Picture of aircraft landing with radar in the foreground

A single-engine plane lands with the aid of a compact, Raytheon-made low-power radar during a flight-check demonstration for the U.S. government.

Your next pizza guy could be a drone. 

Amazon, Uber and a host of other companies are betting big on a future that includes drone delivery services and flying fleets of taxis. But first, the government needs to sort out new flight rules, regulations and standards as well as modernize air traffic control systems to ensure friendly skies for so many unmanned aircraft. Air-traffic authorities must build the infrastructure for a crowded, low-level airspace that's safe for those in the skies and on the ground. That's a challenging task, especially when it comes to urban areas.

Raytheon has a technology that can help bring on the new drone economy. It's called low-power radar, Instead of one, massive radar installation, it consists of smaller, one-meter square Active Electronically Scanned Array, or AESA, software-defined radar units. A network of such small radar units could cover and control the low-altitude flights of smaller craft. 

“It could aid drone delivery services, flying cars, and give you highly localized information like ground fog or flash-flooding in remote or urban locations; things that today’s radars can’t do,” said Michael Dubois, Raytheon’s LPR lead.

In a live flight-check demonstration for U.S. government agencies, Raytheon showcased how its low-power radar can support flights within 20 nautical miles. Air traffic controllers used the radar, which measures a single square meter and uses beam-scanning technology, to guide the pilot to touchdown with surgical precision.

Raytheon is working with small business and academia on a vision: a distributed LPR network that will create a merged, complete picture for multiple missions. Besides supporting safe landings, the network could support aviation surveillance, precision weather observations (including 3-D wind information and urban hydrology), small drone detection and tracking, border security and surveillance, wildfire detection, and elevation and geographic gapfills, providing coverage where none now exists. 

Using LPR, Raytheon could offer radar data as a service, offering data to pilots, companies, the government, weather forecasters and others with a need for low-level radar information, Dubois said.

“This service could be used by media outlets needing information about structures and obstacles before flying a drone over the scene of a news event to shoot footage, or by UberAir to get wind information before dispatching a flying taxi to pick up riders,” he said.

Radar systems tend to be behemoths that can track an aircraft 200 miles out, but they’re limited to how low they can see; hence the term, “flying under the radar.” Structures, like mountains and buildings, and even the horizon create “radar shadows,” which is why military pilots use “nap-of-the-Earth” flying to avoid detection.

Dubois envisioned a distributed network of LPRs every 20 miles or so, mounted atop cell phone towers, mountains and hilltops, and tall buildings. Such a network could monitor activity at very low altitudes.

“If you look for them, cell phone towers and transceivers are everywhere…I’m looking at two right now,” said Dubois from his Raytheon office in Marlborough, Massachusetts. “The reason you see so many is the same reason why we’re proposing the LPR solution: improved coverage, reception and quality despite the curvature of the Earth and obstructions.”

AESA radars offer higher-quality images than conventional radars. “It would be like going from a cathode-ray tube TV to a 75-inch, 4K, HD flat panel,” Dubois said.

And LPR would ultimately cost less to manufacture.

“It’s the economy of scale,” Dubois said. “Instead of building several big things, we’d manufacture thousands of little things. For the amount of money that you might spend on one Ferrari, you could buy a fleet of Mercedes.”

Phased-array radars are also a lot cheaper to maintain. Mechanically scanned radars use rotating parabolic dishes, which are limited in their beam shape, while active phased array radar offers adaptive beam scanning, can track 100 times more targets, and can also interleave between different radar applications. With no moving parts, LPRs are more reliable and easier to maintain, giving them longer lifetimes and lower life-cycle costs.

“We call it graceful degradation,” Dubois said.

Raytheon has done a low-rate initial limited run of LPRs for integration, test and demonstration.

“We’d be ready for deployment as early as 2020,” Dubois said. “And it works; and it works very well.”

Last Updated: 03/27/2018