What’s the best way to detect and destroy drones?

In the northern Danish city of Aalborg, MyDefence makes equipment that jams and deters drones.

“We've had a big surge in interest,” says CEO Dan Hermansen.

He says that until early October his company primarily worked with defense companies, but it has now “completely shifted.”

The small box-shaped kit produced by MyDefence is mainly used by the military of NATO countries and Ukraine.

However, recently demand from civilian customers has increased.

“They come from critical infrastructure,” he adds, “from large companies looking to protect their own assets.”

The device detects communication between the drone and its pilot and then breaks that connection, Mr. Hermansen explains, by emitting a powerful radio signal on the same frequency.

Instead of falling out of the sky, the drone pushes off and lands in a controlled manner. If it tries to reconnect to the GPS signal, that too may be blocked, he adds.

Mr. Hermansen estimates that RF interference is effective against 80-90% of flying drones.

While forcing an unwanted drone to make an emergency landing is a good outcome, it is important to be able to detect it first.

“The first part is really about identification. And the second part is the interceptor system,” explains Kasper Hallenborg, director of the Maersk McKinney-Moller Institute at the University of Southern Denmark.

Identifying a drone is not so easy, says Andreas Grae, research director at the Institute of Military Technology at the Danish Defense Academy.

“[Drones] can be very small or very large and are often made from materials such as plastic or fabric that are very difficult to detect with traditional radar,” he says.

The suite of technologies that will help find drones is in constant development.

These include acoustic sensors that listen for the drone's whirring sound; modern optical cameras with very high resolution; and increasingly sophisticated tactical radars that operate over long distances and can even distinguish a drone from a bird.

Once detected, the drone must be turned off. Electronic jamming like that used by MyDefence has become widespread thanks in large part to the war in Ukraine.

“[Ukraine's] the front lines are completely clogged,” Mr. Grahe says, meaning drone controllers are losing control of their machines.

So Russia and Ukraine have adapted, using drones controlled by fiber optic cables, or using drones that can navigate autonomously or fly along pre-programmed routes.

Such drones need to be intercepted or shot down, and many companies are working on new ways to do this.

Among them is the Swedish startup Nordic Air Defense. The company is developing a low-cost interceptor designed to engage a selected drone and bring it down.

“It’s shaped like a rocket, so it moves incredibly fast,” he adds. “It's incredibly easy to make. It’s essentially 3D printed,” says Jens Holzapfel, the company’s commercial director.

Cost is a critical factor in the fight against drones.

Last month, NATO Secretary General Mark Rutte said: “It is unacceptable to shoot down drones that cost one or two thousand dollars with missiles that could cost half a million or even a million dollars.”

That was a big lesson from Ukraine, says Mr Grae. “It has become a competition of how cheap a drone attack can be carried out and how expensive it is to defend against it.”

“As hostile drones become cheaper, it forces defenders to produce cheaper products,” agrees Mr. Holzapfel.

Low-cost drones are becoming a growing security problem away from the front lines in Ukraine.

Poland and Romania their airspace was violated Russian drones; while isolated drone incidents have been reported in Norway, Sweden, Lithuania, Romania and most recently at Munich airport in Germany.

In Denmark, tensions also escalated following a series of mysterious sightings at airports and military installations around country.

This has prompted the Department of Defense to deploy “multiple capabilities” capable of detecting, tracking and jamming drones; and last week Sweden announced plans to invest more than $365m (£275m) in counter-drone systems, including counter-drone measures and the deployment of hunting drones.

Mr Holzapfel of Nordic Air Defense is currently working with Sweden and its European allies. In addition to the military, clients include law enforcement agencies and security companies.

But he also sees civilian sectors such as shipping and the oil and offshore industries as potential markets.

In a civilian setting. simply shooting down a drone might be too risky.

“It can be quite dangerous,” says Kasper Hallenborg, pointing out falling parts and potentially flammable fuel.

“We saw the consequences in Poland,” he continues. “They were just drone fragments that more or less took the roof off the house.”

Early detection could help, Mr. Hallenborg says: “Then you can probably move it somewhere safer.”

At short ranges, another method is to shoot nets to confuse the drone. Cheap lasers are also being developed.

There are also safer options for so-called soft killing, including hacking. “It's a safer way to take down a drone because then you can actually control the landing,” Mr. Grahe says.

Crucially, a traffic management system is urgently needed, Mr. Hallenborg suggests, including electronic license plates for each drone and a way for users to pre-register a flight.

“We can then quickly determine which drones are allowed to be there and which are not,” says Mr. Hallenborg.

” [Danish] the police are overwhelmed with people telling them what they saw in the sky. Many of these drones are probably there with [legitimate] goal,” he says.