3 ms·

Put sensitive electronics in a metal box, comms over a fiber (already common), and you’re good to go. Only tricky thing is if currents induced in motors are to

Put sensitive electronics in a metal box, comms over a fiber (already common), and you’re good to go. Only tricky thing is if currents induced in motors are too hard to reject in driver circuitry, tho even at the extreme this should be possible to insulate with capacitors (or worse/heavier with transformers)

varjag 1y ago
Sounds like a great plan if you don't need a camera, positioning and magnetic compass. You also want your cage grounded or very thick, otherwise with sufficiently strong field it will become preemable.
- pulse7 1y ago
  You can put camera in transparent Faraday cage. With camera and gyro one can do basic positioning...
  - XorNot 1y ago
    Basic yes, but drones are precision strike weapons by necessity: they can't carry enough payload to kill everything in a 50m radius for example. They depend on generally nailing a single target with cm-level precision. And all that stuff is a new supply chain and more weight which isn't payload. That a countermeasure can be built doesn't mean it's necessarily effective to do so - your drones get less cheap, less numerous, you have to incorporate such systems into tactical and strategic planning.
    - imtringued 1y ago
      Also you can't buy the drones off AliExpress anymore. This shouldn't be underestimated, because all the drone swarm wet dreams were built on this.
    - ReptileMan 1y ago
      >payload to kill everything in a 50m radius for example. cluster heads solve this beautifully because 1kg of high explosive kills everything good enough in 5 meters radius.
      - XorNot 1y ago
        Which is still nothing in terms of area lethality terms. For comparison, the Excalibur GPS guided artillery shell was considered precision because it would hit within 5m reliably. Compare to the lethal range of a 155mm, where the kill radius is 50m and casualty at 100m.
        ReptileMan 1y ago
        155mm has payload of around 7kg.
    - themgt 1y ago
      You're talking about a counterdrone system that's at technology demonstrator stage. I don't think they even have any contract or timeline for delivering production systems. Meanwhile tech used in the Ukraine war is adapting by the month. "That a countermeasure can be built doesn't mean it's necessarily effective to do so" applies especially to reading a corporate press release about a system doesn't even have a timeline for being on the battlefield.
  - Animats 1y ago
    More than basic. DJI offers full GPS-less camera and accelerometer based nav technology on their drones.
- KK7NIL 1y ago
  A compass is not blocked by a Faraday cage as low frequency magnetic fields still get through.
  - varjag 1y ago
    I was thinking a ferrous shield would warp magnetic flux lines but I could be wrong. And guess you could mill the enclosure from brass, tho it's still not clear how would you get an RF ground up there.
    - KK7NIL 1y ago
      > ferrous shield would warp magnetic flux lines It wouldn't, the only way to "shield" from magnetic fields is to get them to induce Eddy currents and but that requires more and more length and as the wavelength gets longer and essentially infinite for the Earth's field which is very slow moving. > RF ground up there. "ground" is relative and not at all required for a Faraday cage to work.
      - spwa4 1y ago
        However that is still vulnerable to the microwaves. The issue is that this setup catches microwaves and while, yes, it prevents the waves from entering the electronics it does so by converting them to heat. So if this cage has caught 100J * volume (say 100W for slightly over 1.5 minutes), the electronics are above 100 degrees, and the solder joints are releasing. The advantage of microwaves is that unlike lasers, kilowatt strong microwaves are easy to generate, it is an incredibly well studied problem, because that's how early radar systems worked. They are what secured the skies above London against the Nazi air force. Israel seems to be trying another approach with lasers. They decided it doesn't matter if the laser is powerful, if you just have hundreds of 2W lasers aimed at the same target.
cyberax 1y ago
Or you can put motors inside the cage, with purely mechanical linkage to the propellers.
- varjag 1y ago
  You'd have to make sure the linkages are not conductive and there is not even a 1mm clearance on their ports in the enclosure. Non-metal axles are possible but it's hard to find material that would withstand the torque. You also need to think through your cooling solution. Enclosed batteries, converters and motors will generate a lot of heat over typical mission, and you don't have the benefit of direct air cooling anymore.
  - amluto 1y ago
    How about using a metal axle that penetrates the cage using an intentionally conductive bearing, i.e. a slip ring? It would need very low RF impedance, but it would only need to last for the expected lifespan of the drone. At just a few GHz, metal mesh ought to be adequate for the cage material, so cooling isn’t necessarily a huge problem.
topspin 1y ago
> Only tricky thing is if currents induced in motors Many of the drones in the Russia-Ukraine war are powered by ICEs. I'm thinking of Ukraine's long range drones presently deleting Russia's refinery distillation towers, fixed radar installations, parked aircraft, ammo dumps, etc. Those engines are not purely mechanical, but purely mechanical engines have been widespread and are still commonplace today. A 2-stroke diesel being one example, but even gas turbines can be purely mechanical. So one can imagine such an adaptation in response to microwave countermeasures.
Animats 1y ago
The motor drive side probably isn't that vulnerable, since that's the output side of large power transistors, but the Hall-effect sensors and current sensing in brushless DC motors might be a problem. But you don't have to use brushless motors. They last longer, but drones are ammo, not assets, today.

varjag 1y ago

Sounds like a great plan if you don't need a camera, positioning and magnetic compass. You also want your cage grounded or very thick, otherwise with sufficiently strong field it will become preemable.

pulse7 1y ago
You can put camera in transparent Faraday cage. With camera and gyro one can do basic positioning...
- XorNot 1y ago
  Basic yes, but drones are precision strike weapons by necessity: they can't carry enough payload to kill everything in a 50m radius for example. They depend on generally nailing a single target with cm-level precision. And all that stuff is a new supply chain and more weight which isn't payload. That a countermeasure can be built doesn't mean it's necessarily effective to do so - your drones get less cheap, less numerous, you have to incorporate such systems into tactical and strategic planning.
  - imtringued 1y ago
    Also you can't buy the drones off AliExpress anymore. This shouldn't be underestimated, because all the drone swarm wet dreams were built on this.
  - ReptileMan 1y ago
    >payload to kill everything in a 50m radius for example. cluster heads solve this beautifully because 1kg of high explosive kills everything good enough in 5 meters radius.
    - XorNot 1y ago
      Which is still nothing in terms of area lethality terms. For comparison, the Excalibur GPS guided artillery shell was considered precision because it would hit within 5m reliably. Compare to the lethal range of a 155mm, where the kill radius is 50m and casualty at 100m.
      - ReptileMan 1y ago
        155mm has payload of around 7kg.
  - themgt 1y ago
    You're talking about a counterdrone system that's at technology demonstrator stage. I don't think they even have any contract or timeline for delivering production systems. Meanwhile tech used in the Ukraine war is adapting by the month. "That a countermeasure can be built doesn't mean it's necessarily effective to do so" applies especially to reading a corporate press release about a system doesn't even have a timeline for being on the battlefield.
- Animats 1y ago
  More than basic. DJI offers full GPS-less camera and accelerometer based nav technology on their drones.
KK7NIL 1y ago
A compass is not blocked by a Faraday cage as low frequency magnetic fields still get through.
- varjag 1y ago
  I was thinking a ferrous shield would warp magnetic flux lines but I could be wrong. And guess you could mill the enclosure from brass, tho it's still not clear how would you get an RF ground up there.
  - KK7NIL 1y ago
    > ferrous shield would warp magnetic flux lines It wouldn't, the only way to "shield" from magnetic fields is to get them to induce Eddy currents and but that requires more and more length and as the wavelength gets longer and essentially infinite for the Earth's field which is very slow moving. > RF ground up there. "ground" is relative and not at all required for a Faraday cage to work.
    - spwa4 1y ago
      However that is still vulnerable to the microwaves. The issue is that this setup catches microwaves and while, yes, it prevents the waves from entering the electronics it does so by converting them to heat. So if this cage has caught 100J * volume (say 100W for slightly over 1.5 minutes), the electronics are above 100 degrees, and the solder joints are releasing. The advantage of microwaves is that unlike lasers, kilowatt strong microwaves are easy to generate, it is an incredibly well studied problem, because that's how early radar systems worked. They are what secured the skies above London against the Nazi air force. Israel seems to be trying another approach with lasers. They decided it doesn't matter if the laser is powerful, if you just have hundreds of 2W lasers aimed at the same target.

cyberax 1y ago

Or you can put motors inside the cage, with purely mechanical linkage to the propellers.

varjag 1y ago
You'd have to make sure the linkages are not conductive and there is not even a 1mm clearance on their ports in the enclosure. Non-metal axles are possible but it's hard to find material that would withstand the torque. You also need to think through your cooling solution. Enclosed batteries, converters and motors will generate a lot of heat over typical mission, and you don't have the benefit of direct air cooling anymore.
- amluto 1y ago
  How about using a metal axle that penetrates the cage using an intentionally conductive bearing, i.e. a slip ring? It would need very low RF impedance, but it would only need to last for the expected lifespan of the drone. At just a few GHz, metal mesh ought to be adequate for the cage material, so cooling isn’t necessarily a huge problem.

topspin 1y ago

> Only tricky thing is if currents induced in motors Many of the drones in the Russia-Ukraine war are powered by ICEs. I'm thinking of Ukraine's long range drones presently deleting Russia's refinery distillation towers, fixed radar installations, parked aircraft, ammo dumps, etc. Those engines are not purely mechanical, but purely mechanical engines have been widespread and are still commonplace today. A 2-stroke diesel being one example, but even gas turbines can be purely mechanical. So one can imagine such an adaptation in response to microwave countermeasures.

Animats 1y ago

The motor drive side probably isn't that vulnerable, since that's the output side of large power transistors, but the Hall-effect sensors and current sensing in brushless DC motors might be a problem. But you don't have to use brushless motors. They last longer, but drones are ammo, not assets, today.