Can Pocket-Sized Radars Protect Us From Drones—and Drone Col…

Unmanned Aerial Systems, or “drones” in everyday speech, are becoming ubiquitous in today’s world—and that poses mounting security challenges in many spheres f life.

Civilian airports like London Gatwick have been repeatedly shutdown by unauthorized drone overflights, and outdoor events face harassment from drones. Worse, drones could easily be applied for espionage or sabotage of industrial facilities and critical infrastructure.

Meanwhile on battlefields ranging from Ukraine to Syria, insurgents have jury-rigged civilian drones for surveillance missions and to launch lethal attacks carrying small explosive payloads.

Not to be outdone, militaries are procuring their own purpose-designed kamikaze drones like the Switchblade loitering munition, Israel’s Harops, Russia’s Kalashnikov drone, and Turkey’s new Kargu-2 swarming drones.

A small drone has even been used in an unsuccessful assassination attempt on a head of state.

Therefore, both civilian and military security systems increasingly need to be able to detect, classify and track drones. But small drones can be particularly difficult to detect due to their small radar cross sections and ability to use terrain to mask their approach.

Furthermore, many traditional infrastructure security systems remain focused on threats at ground level—while air defense systems are mostly designed to tackle larger, higher-flying aircraft.

And even in the absence of aggressive intent, both human-operated and autonomous drones need better sensors to avoid running into things, including other drones.

Eben Frankenberg, CEO of the company Echodyne, is proposing his own unique solution to these challenges: take the sophisticated electronically scanned phased-array radar technology used by military jet fighters to track bogies from dozens of miles away, and scale it down it to something you could easily hold in one hand for a fraction of the price.

Phased Arrays You Can Fit in Your Pocket

Kirkland, Washington-based Echodyne was founded in 2014 and counts only around 85 employees. However, both the company and its radars have won a series of awards including first place in the 2018 ThunderDrone event hosted by the U.S. Special Operations Command.

Unlike traditional radars that mechanically rotate their antennas and can only “look” in one direction at a time, a phased-array system uses a phase shifter in each array element to steer the beam without physically moving the antenna, allowing it to quickly scan any aspects of its arc in milliseconds.

Frankenberg’s innovation, which he calls the Metamaterial Electronically Scanned Array (MESA) does away with the phase shifters. Instead, it uses many finely separated antenna feeds which can be activated in different combinations to construct a quasi-planar beam aiming in the desired direction. (Technically, EchoGuard is a PESA radar in which the elments are connected to a single transmitter, rather than more exotic multi-transmitter AESA radar.)

As a result, he claims, the MESA is simpler, less costly, weighs less and requires less battery power than a traditional phased array radar, while retaining much of its agility.

“You can do interesting things by getting down to about a 1/10 of the wavelength with just the material itself,” Frankenberg told me in an interview earlier in June, noting it’s not the materials that are new but rather the physics design approach of using many more finely spaced antennae without phase shifters.

His company’s EchoGuard radar is smaller in surface area than an iPad Mini at 7.3×4.7”, weighs less than three pounds, and runs on less than 50 Watts of electricity, but can scan an arc up to 120 degrees wide (azimuth) and 80 degrees high (elevation), meaning it can simultaneously surveil surface and aerial tracks. That means three EchoGuards networked together could provide a 360-degree surveillance “bubble”.

The K-Band (24.5 Gigahertz frequency) 1.25 centimeter-wavelength system is suited for short-to-medium range, high-resolution three-dimensional scanning: reportedly, it can detect a Cessna-sized aircraft up to 1.5 miles away, quad-copter style UAVs like the Phantom 4 a half-mile away, and palm-sized micro-drones at a distance at 200 meters (two football fields).

Like military phased array radars, EchoGuard can near-simultaneously perform wide-area scans and narrow, focused tracking of up to twenty objects. For example, it could refresh multiple widely-spaced tracks ten times in one second (10 Hertz), and still perform wide area sweeps in between. This is vital given the emerging threat posed by swarms of cheap drones intended to overwhelm security systems.

Furthermore, it can generate more accurate data by bracketing a radar track with five beams and then interpolating the returns, a technique known as “sequential lobing.” At medium distances, the EchoGuard can classify drones by type and cue other sensors for targeting and counter-measures.

Admittedly, laser-based LIDAR, electro optical and infrared sensors are also effective at at these ranges. However, these sensors can degrade in effectiveness under low-visibility conditions, whereas radar can see through fog or dust.

When I inquired about price, Frankenberg indicated the EchoGuard unit price was clocking in the $10,000s, which he characterized as being an order of magnitude cheaper than traditional commercial phased arrays.

Counter UAS and Surveillance

Echoguard radars have already been integrated into security systems such as the Moog counter-UAS sensors protecting the launchpads at NASA’s Kennedy Space Center. Black Sage’s UASX system integrates EchoGuard with infrared cameras and radio frequency jammers to disable drones.

EchoGuard also features in the suite of sensors used by Anduril surveillance towers, which have been controversially used to detect border crossings by migrants, as well as for security at military bases.

It struck me that such light radars could be carried by, say, a light infantry platoon as a portable perimeter surveillance system.

Frankenberg said they had indeed developed a “rapid deployment kit—one of our handheld radars with a tripod and connector cables and tablet-compatible Android-based UI that you can set up in the field. That will detect people at 2.2 kilometers (1.4 miles), or it can be used for aerial-detection.”

The kit, which has already received some military orders, weighs two pounds, plus four pounds for batteries, and costs around $50,000.

I also inquired if EchoGuard could produce a “weapons-grade track”, ie. data precise enough to target weapons. Frankenberg said it could, and that among the 30-40 systems Echo radars had been integrated into include laser- and gun-based systems (likely for short-range air defense systems) and drone-interceptor aircraft.

However, EchoDyne’s radars are not designed to execute jamming attacks themselves, Frankenberg emphasized, though they can cue a jammer used to disable drones. My impression was the company has eschewed direct electronic attack capability to avoid running afoul of International Traffic in Arms Regulations (ITAR).

EchoGuard is also suitable for tracking small boats and UAVs at sea, and has been deployed for use in port security as well as on aquatic platforms. Marketing VP Leo McCloskey explained they were working on software algorithms to reduce surface clutter in higher sea states (ie. larger waves).

Frankenberg also said the radar had the fidelity and reaction speed for integration into an Active Protection System—a vehicle-mounted system designed to detect incoming anti-tank projectiles and either disrupt or destroy them—though he could not speak as to whether it had been tested in that role. The U.S. Army is currently test-integrating APSs in its armored vehicles.

Similarly, the MESA radar could have application as a Hostile Fire Indicator (HFI) for military helicopters—a sensor that alerts helicopters crews if they’re being shot at, and where the fire is coming from.

The MESA radar’s ability to generate high-resolution radar imagery made me curious if it could be used like a Synthetic Aperture Radar (SAR) capable of performing detailed scans of the terrain below. Frankenberg told me EchoDyne was investigating that possibility, though he explained it would operate a roving ‘searchlight’-style sensor rather than a wide-area scanner, and thus require development of a gimbaled mount and improved processing.

The Range Conundrum

While EchoGuard may be effective in detecting small unmanned aerial systems (SUAS) that are limited in payload and maximum altitude, larger combat drones such as the Chinese- and Turkish-built types used in the Libyan Civil War, can fly high enough, and attack from far enough away with guided weapons, so as to exceed its 1.5-mile scanning range.

For that reason, even short-range air defense systems like the Russian Pantsir-S tend to use radars that can detect targets 10 to 20 miles away and up to 20,000 feet or higher. And even that range hasn’t prevented Pantsir systems from falling victim to drone attacks.

Thus, I asked Frankenberg if they were looking into scaling up his MESA radar for longer detection range.

“We’re working on that, but we can’t share the details now,” Frankenberg told me, adding more may become public next year. “There’s nothing intrinsically limiting the range.”

While increasing range would entail greater antenna size, it might still have similar benefits compared to other commercially available systems..

Still McCloskey emphasized their short-range radar covers an Achilles heel of sorts for many longer-range radars. “[Right now] we’re in the donut hole sort of space of 2-3 kilometers. Competing radars have fairly narrow elevations. We catch [drones] within that phase for interception.”

Radar You Could Parallel Park With?

Frankenberg also is pursuing a very different application for his lightweight radars: collision avoidance. 

The idea is to give even small drones their own organic sensors to avoid colliding with other drones or light planes, enabling Beyond Visual-Line of Sight (BVLOS) operation of the drones that ordinarily wouldn’t be able to range very far.

His EchoFlight Air-to-Air Collision Avoidance Radar weighs between 1.6 to 1.8 pounds depending on cooling method ,and can detect light airplanes out to 1.24 miles away and small UASs around a half-mile distant.

But there are also collision-avoidance applications on land or even at sea thanks to the MESA radar’s agility, high resolution and short-range capabilities. “You can put this on USV [Unmanned Surface Vessel] and use it for docking,” Frankenberg points out.

Even manned helicopters or tilt-rotors could use radars as a Degraded Visual Environment imager, a sensor that aids in flight operations in low-observability conditions such as fog, dust clouds kicked up by rotors and so forth.

Frankenberg especially saw promise in a project to integrate a MESA radar called EchoDrive into driverless cars. These could acquire much more precise three-dimensional data beyond the basic two-dimensional capabilities of current driverless-car radars, allowing rapid classification of objects and more precise measurements.

I asked if it could give precise enough coordinates for a driverless car to parallel park with—my least favorite aspect of urban driving—and Frankenberg claimed that it was.

He also noted that an unmanned ground combat vehicle (UGCV) would surely require three-dimensional scanning when negotiating off-road terrain.

Frankenberg told me he expects clients will find many other applications for his tiny radars, describing one client that used the EchoGuard radar to detect avalanches near roads running through mountain passes.

“They shut a highway down right before some traffic was going through because an avalanche was starting. They saved three or four cars from getting covered by this avalanche. You would never have thought about that application.”

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