Deep Dive: Faraday cage use in Russia-Ukraine drones

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The frontline between Russian and Ukrainian forces in eastern Ukraine is the most signal-dense warzone in human history.

Spoofers and jammers send out continuous signals that disrupt broad spectra of radio and GPS signals, while ‘drone guns’ send more targeted blasts of frequency.

And yet, while many fall to these cascades of electricity, drones continue to fly across no-man’s land and beyond. 

Many of the most effective protections are simpler — and older — than you might think.

One that’s seen new life on the frontlines is the humble Faraday cage.

At its most basic, a Faraday cage is effectively insulation for radio and electrical frequencies — analogous to soundproofing or thermal homewrap. 

The core principle is that electrical charge stays on the surface of a conductor rather than going through it. Physicist Michael Faraday demonstrated this phenomenon almost 200 years ago in a foil-lined room, but something resembling a Faraday cage can be as primitive as a paranoiac’s tinfoil hat. 

At the time of its invention, there were precious few electronic or radioactive frequencies to defend against. Nowadays there are many more threats in this realm. 

The Faraday cage remains, however, a powerful means of preventing hacking and electronic attacks.

“It's not necessarily a box, so to speak, but it's like a shield,” said Oleksandr Barabash, Chief Technical Officer of Falcons, a Ukrainian miltech firm that identifies and hunts for Russian electronic signals. “A Faraday cage is just to isolate your devices from the EW and any radio signals that can come in and be like interference to your devices.”

Microwaves use Faraday cages to keep their radiation from spilling out — part of why they are unlikely to cause cancer even if you are standing right in front of their front screens, contrary to popular misconception. Chelsea Manning used this same trait, making guests leave cell phones in a microwave before meetings to avoid electronic surveillance.

More complicated Faraday cages use alternating layers of conductive and insulating materials to encase the computation banks of great data centers and to guard national secrets. The facilities in which US officials and contractors view the most classified types of information are made according to TEMPEST qualification, a type of Faraday cage.

Drones are a different story — highly mobile, but very much in need of protection from electronic attack. General Atomics’ Reaper drones have a copper mesh under their composite exteriors that performs a similar function in motion. But they have a wingspan of over 40 feet and cost somewhere in the vicinity of $32 million.

Drones in the Russia-Ukraine War are almost diametrically opposite. The bulk of drones on both sides are quite small, with payloads limited to two or three kilograms. More critically, the most in-demand variety is the kamikaze drone, which is meant for a single flight, never to return again.

And yet such small, lightweight and inexpensive drones are still being treated to electronic protection. Many are wrapped in ‘Faraday cages’ of no greater sophistication than a tinfoil hat — some are actually just wrapped in aluminum foil.

But the experiments are unending. Recent photos from a Ukrainian Telegram channel dedicated to electronic war show what seems to be 3D-printed spheres with elaborate internal grids — a homemade Lunebгrg lens, a device that amplifies an antenna’s effectiveness — to be wrapped in foil and put into chambers of a drone body, evidence of increasing sophistication of homemade efforts to seal off various parts of a drone from electromagnetic interference.

Most drones, and almost all high-end varieties, have electronic shields of some kind.

“If we're talking about the GNSS system, or positioning modules, like GPS, or any other protocol you can use to determine your position on a battlefield or anywhere global, you need some sort of protection against the jammers and the spoofers,” said Barabash. “Then you can use this type of enclosure just to protect your antenna sets or one antenna, if you have one antenna, from being jammed on your rocket or UAV.”

The issue with an ideally “sealed” Faraday cage is that while it provides stronger protection from any electronic interference, it also prevents contact from the pilot.

It is a trade-off. Barabash said, “The idea of using the Faraday cage is just to prevent any signal incoming towards you, from your perspective as well. So you're not going to send any signal either.”

“Using metal housing to protect electronics from powerful EM beams is always a compromised solution. You have to choose between the weight of your UAS capabilities and the payload,” said Maksym Prasolov, co-founder and Chief Growth Officer of drone company Bavovna AI. 

Rather than a conductive metal, Bavovna uses a polymer composite that mutes interference only from certain radio frequency ranges. By Prasolov’s account, they have achieved electromagnetic muting of -93 decibel milliwatts — a massive reduction that if accurate turns a drone gun into something resembling background noise. 

There are other strategies to abandon signal dependence in flight, operating without the need for a pilot. The hotly-anticipated development is greater AI integration. But in many cases, the solution has been to pre-program flights.

Russian Shaheds, which make it deep within Ukraine, are often set upon pre-mapped and programmed routes far beyond Russian radio connection, said Barabash.

Shaheds’ dependence on visual guidance means that they often flock to the highway between Odesa and Kyiv; or the Dnipro River which they use as a guideway to Ukraine’s capital city. Ukrainian soldiers wait along these chokepoints with anti-drone guns like the locally made Kvertus AD G-6+, which sends out a powerful radio signal. Machine guns are also a popular solution.

Ukrainian company Tyman is among many that produces “domed” antennae that use Faraday properties — in one commercially-available case, galvanized steel and insulating ABS plastic — to protect against interference, while narrowing the bands of electromagnetism to which they are sensitive. Those domes allow omnidirectionality — reception from all angles — but limited range. 

Russia’s now-infamous ‘glide bombs’ are another example of a weapon with a high degree of EW resistance. They are old Soviet bombs weighing between 500 and 3,000 kg outfitted with new wings and GPS devices that are, thus far, impossible to stop in flight near to the Russian line.

Part of the advantage of these glide bombs is their weight. Unlike Russian rockets, they’re too heavy to just blow up mid-air. But they are also outfitted with “Kometa” antennae units — a highly functional brand from Russian company VNIIR-Progress, which has dodged Western sanctions on their components. 

Such units are termed controlled reception pattern antennas, or CRPAs. They isolate the origin of signals, allowing them pretty clear vision through electromagnetic murk. 

And so they remain a covetable item for Ukrainians. Ukrainians salvage these CRPAs from Russian strikes and repurpose them. Barabash has one that he is currently working to reverse engineer, with the aim of making some that they can sell for $1,000 each instead.

Serhiy has been in the Ukrainian military for five years, serving as a drone pilot since 2022. We’ve omitted his last name at his request due to security issues. He said he is much more impressed with good CRPA systems than with signal shielding.

“Foil lights up a lot on radar,” Serhiy cautioned from his post in Kharkiv oblast. “On cheaper drones they play around with antennae, filters and other gizmos like that. On the bigger ones they’re already putting directional antennae, which are noticeably more resilient to EW.”

“For control stations, the focus is on maintaining a strong link over long distances, so techniques like DF (directional antennas) or frequency hopping are often used to cut through interference. Onboard the drone, though, components like compass/GPS/visual sensors/cameras, and the VPU [visual processing unit] needs direct EMI shielding to be protected from the ground,” Prasolov wrote to Counteroffensive.Pro.

These solutions may ultimately lead to the obsolescence of jammers and spoofing systems.

“My personal view is that sooner or later jam systems will not work,” said Balabash, noting the rise of AI in the ‘last mile’ of FPV drone attacks. “It's just not gonna work in the near future. That's why we aren’t even considering making our own jam solution.”

But what becomes the best solution if EW stops working on Russian drones? 

Simple, said Barabash: 

“Shoot them down using your bullets.”

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