Weaponized drones pose a clear and escalating threat to deployed U.S. forces. The increased danger means that layered counter-drone approaches are now essential for detecting, identifying, tracking, and killing not just lone drones but coordinated groups and swarms.

Weaponized small drones – inexpensive unmanned aircraft systems (UASs) – have emerged relatively quickly as a major threat to deployed U.S. forces, particularly infantry units, according to a new report by the National Academies of Sciences, Engineering, and Medicine. While the U.S. Department of Defense (DoD) has developed tactics to counter single drones, the report says there’s an urgent need to develop countermeasures against multiple drones organized in coordinated groups or swarms.

Why are drones a threat? Because they can be easily modified to carry lethal weapons, identify targets at long ranges, and carry out electronic warfare (EW) attacks. Moreover, adversaries can launch coordinated group or swarm attacks at a surprisingly low cost.

“Modified hobby drones can be used to support conventional and unconventional attacks,” says Albert Sciarretta, president of CNS Technologies (Springfield, Virginia) and chair of the committee behind the report. In fact, drones can be fitted with external or embedded explosives designed to explode on contact, or an adversary can use drones to attempt to jam U.S. forces’ radio-frequency (RF) signals or to support clandestine information-gathering operations.

The National Academies report highlights the fact that although the DoD has invested significantly in technologies to counter these threats, the focus is often on detecting RF transmissions of the UAS or their operators. Consumer and customized small UASs, however, are increasingly operating without RF command-and-control links by using automated target recognition and tracking, obstacle avoidance, and other capabilities enabled by software.

Thankfully, counter-drone technologies do exist and are ready to deploy today. The focus is now shifting to layered solutions, to ensure that a user can counter whatever comes at them. While no means an exhaustive list, let’s take a look at three of the different types of counter-drone technologies available now.

Handheld counter-drone solution

Battelle – a global research and development organization headquartered in Columbus, Ohio – is developing counter-UAS solutions across the entire range of detect, track, identify, and defeat actions.

Threats posed by drones have “emerged and continue to evolve remarkably quickly,” says Daniel E. Stamm, manager of Battelle’s Counter-UAS Program, Integrated and Unmanned Systems. The level of sophistication in communication between an unmanned aerial vehicle (UAV) and its ground-control station – available for less than $1,000 – is “absolutely remarkable,” he adds. “Makers of small commercial drones are pushing nuanced communication capabilities beyond that which was almost considered inconceivable just a few years ago.”

This reality is largely thanks to the commercial small UAS industry’s investments “into technologies to enable longer stable flights with more impressive payloads,” Stamm points out. “But it yielded a situation in which nefarious actors can present extremely effective threats to our nation’s security and that of our allies without having to develop the technology or capabilities themselves.”

It’s challenging to keep counter-UAS technology abreast with the UAS capability it is intended to oppose. “The DoD, other U.S. organizations, and many allied-nation agencies are working to identify and document the requirements for near-term and future UAS technologies,” Stamm says. “But this is a very difficult process, especially with such a rapidly evolving threat and a federal acquisition process that isn’t tailored to incentivize agility and innovation. In the meantime, the defense industry is making significant investments to attempt to stay in front of the evolving threat.”

Stamm’s research group is developing relatively small, lightweight, and easy-to-operate solutions that will be useful in military and warfare situations, as well as in nonwarfare situations. “The largest portion of the UAS threat is probably to the U.S. military at this time, but the UAS threat is likely going to become a much wider reality in the not-too-distant future,” he says.

One of Battelle’s solutions is the “DroneDefender” family, which provides an easy-to-use, lightweight, nonkinetic, point-and-shoot way to defend airspace ranges of up to 400 meters against UASs, such as quadcopters and hexacopters. (See Figure 1.)

Figure 1: Battelle’s DroneDefender is an easy-to-use, lightweight, nonkinetic, point-and-shoot option for defending airspace ranges of up to 400 meters. Image courtesy of Battelle.

SWaP (size, weight, and power) is “extremely important within this realm,” Stamm notes. “Our warfighters are already burdened with physical and cognitive loads. It’s essential to consider this when developing UAS solutions, and to make them as useful and functional as possible for our warfighters.”

High-power microwave technology

Among the most intriguing counter-drone solutions is a high-power microwave technology from Raytheon (Waltham, Massachusetts), which essentially uses the same technology as household microwaves but is millions of times more powerful.

“The pulse that comes out of our system is very short – nanoseconds long at extremely high power,” says Susan Kelly, site director of the Raytheon Albuquerque group. “Our high-power microwave technology destroys the electronic components in UAVs, as well as Class 1 and 2 drones. It has a relatively large beam width, so it’s different than a laser, which is very accurate and pinpoints a target, but has to stay on the drone for a few seconds to do any damage.” It’s important to note that this isn’t the same microwave technology used for crowd control, which makes a target’s skin feel as if it’s burning.

High-power microwave is nearly instantaneous and kills anything within a large swath. “It’s directional – you can point it in a given direction,” explains Kelly. “This makes high-power microwave a good method to counter swarms. If we’ve got three or four drones coming in from the north at 10 to 20 degrees away from each other, we can point our system at it and take them down with one shot. We’ll shoot rapidly multiple times, but that’s just to ensure we got them all. Then, we can turn our antenna to the next area where drones are coming in and take them down as well.”

Technology to get swarms to communicate with each other is improving, and counter-UAS technologies exist that make use of the data link between the drone and its ground station that controls it by jamming or using cyber effects to confuse it. “For drones that are fully autonomous – guided via waypoint, without a link back down to the ground station – jamming techniques won’t work. Raytheon’s high-power microwave technology doesn’t require any of this because it directly affects the drone itself,” she explains.

The system’s users control it on-site today, but in the future it may be operated remotely or autonomously. “You can put these around a runway or base to protect it from drones,” Kelly says. “We have a concept to put it on ships, but it’s a little more difficult because deck space is at a premium.”

Raytheon’s high-power microwave is primarily custom-built and doesn’t rely on commercial off-the-shelf (COTS) components. “Most of the critical parts in the high-power microwave system were designed by us,” Kelly says. “It’s not your grandfather’s radar. The amount of power that comes out of a traditional radar, to track an airplane for example, is minuscule compared to the amount of power our system sends out [the numbers are classified].”

Since base commanders are unlikely to want to rely solely upon any single solution to counter drones, “it’s all about having a layered defense and multiple ways to take these drones out,” Kelly says. “Our concept is that you’d have a high-power microwave system forward-deployed around a base that would take the first shot against drones. If for some reason it doesn’t get them all, you take another shot because it’s an unlimited magazine. No reloading … just keep shooting.”

But if a threat helicopter swoops in, you wouldn’t fire a high-power microwave at it. “You’re going to want to have a missile available, because it’s an easy cost exchange to fire a missile at a helicopter,” Kelly explains. “And you probably want a laser available as another tool. High-power microwave is a first line of defense because its range is pretty far, but laser range is even farther if the weather is good. The weapon of last resort is going to be whatever missile you deem necessary to do the job – you don’t want to spend $1 million to take out a $1,000 drone.”

Mobile counter-drone solution

A mobile counter-drone option, developed by SRC Inc. (North Syracuse, New York), called Silent Archer, features TRL 8/9 radar and EW systems, a camera, and a 3-D display. “It uses a radar system for detecting and tracking, and from that we can slew a camera to put eyes on a target,” says Dave Bessey, assistant vice president of Counter-UAS Business Development for SRC. “In the same period of time, we’re also looking for emissions off enemy aircraft, UAVs, and UASs.” (Figure 2.)

Figure 2: A sample configuration of SRC’s Silent Archer UAS technology, which detects, tracks, identifies, and defeats drones using electronic countermeasures while on the move. Image courtesy of SRC Inc.

Once it’s determined a drone is entering a zone that needs to be protected – critical infrastructure, land forces, or a port or harbor – a decision is made whether to launch a nonkinetic attack. “Nonkinetic attacks can range from jamming communication links between the operator and UAV to getting involved in their video feed or more advanced techniques [which are classified],” Bessey explains. “But the enemy is continually improving their capabilities, so we need to stay ahead. We can also cue kinetic weapons, because we have customers who want a last line of defense so that in case something gets past the nonkinetic response they’ll be able to cue a missile, bullet, or other UAV to go up and attack the incoming UAV.”

When it comes to reaction time to hostile drones, “we need radars and electronic warfare,” Bessey says. “We need to be looking at two things: where they’re coming from a distance, and when you need to make a decision about whether they’re doing an ISR [intelligence, surveillance, reconnaissance] mission or bringing in a weaponized drone against you. This dictates how far out you need to attack them. And we’re talking seconds or less than minutes to be able to identify the target, [ascertain] the enemy, and make a determination about the response needed.”

Silent Archer uses a layered approach. “The radar does passive detection,” notes Paul Tremont, president and CEO of SRC. “And a drone doesn’t need to be communicating with a controller for us to detect and cue devices to defeat it in a nonkinetic way. But if it is communicating, we have an electronic system that can impact it, and we can put eyes on it with sophisticated cameras that can see quite far.”

Today, soldiers are in the loop with Silent Archer, “but every year, we’re automating it more so that in the future it’ll be a completely automated system,” Bessey notes.

Swarms on the horizon

Swarms and more coordinated attacks are the new reality for deployed forces. “Fighter jets use a ‘hunter-killer’ tactic, in which one goes forward to search for targets while a guy in the back has the missile for the kill,” says Raytheon’s Kelly. “Drones do this, too. And just because we kill the first drone doesn’t mean the second one can’t still carry out its mission. When attacks are coordinated, if you take one drone out you maybe get a mission kill. But drone technology is advancing so fast, and anything we’re doing the bad guys are doing. If you talk to the warfighter, they’re worried.”