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Comment by TheRealPomax | Hacker News Reader

Did they also trial it against a drone swarm that knew about THOR (which an assailant would) and had put the drones in "not even Faraday mesh" but just a fairly open wire sphere because microwaves are trivially neutralized with a "mesh" that has several inches of space between the wires?

(E.g. wired cages that are already commonly used by drone-operators in the ducting/smoke stack/container/etc inspection business to prevent their $50k industrial drones from crashing into walls/ceilings)

Because a test that doesn't test "what happens when the enemy knows the weaknesses" is not a test.

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> put the drones in "not even Faraday mesh" but just a fairly open wire sphere because microwaves are trivially neutralized with a "mesh" that has several inches of space between the wires?

My physics is getting a little rusty, but I wonder - are microwaves going to "flow around" this mesh, or "flow through" (following a path along the surface and not leaking inside, ofc.)? Because if it's the latter, then I'd guess that enough energy pumped into microwaves will melt the Faraday cage.

Very true, although the question is at what distance it would effect that, because a clustered explosive payload just needs to go off near the target and have the pressure wave do the rest. Going off "on" the target is ideal, but not strictly necessary to do the damage it needs to do.

So I'm thinking - on the one hand, the effectiveness of microwaves drops with r². On the other hand, this solution enables continuous tracking and delivery (whether the beam itself is continuous or pulsed), and it only uses electricity, which may have significant logistics benefits over any kind of physical projectile.

Definitely, but when it comes to counter-offensive, the same rules apply: you don't need to blow up each drone in a swarm. You just need to cause a big enough explosion near enough drones (just like how we don't shoot airplanes or ships by direct impact anymore, we "make thing go boom" close enough to a plane or ship to cause enough catastrophic damage to the flight surfaces/hull and if there's a direct impact, that's just a bonus)

It's 1/r², and the pulsed currents induced into the proposed wire mesh would likely produce some strong local EM effects -- possibly enough to overwhelm the rest of the drone electronics.

Sure, you could build a drone to resist this sort of attack, but SWAP would go way up, and range + mission effectiveness would go down.

I wonder if pulse-wave beamforming can amplify the microwaves to the point where it is < 1/r^2.

You are way way off on your faraday cage gap sizing.

In order to block EM fields with frequencies of 10 GHz and lower, the hole size of the Faraday cage should be smaller than 3 mm.

You want the hole to be less than 1/10th the wavelength of the frequency you’re trying to block

> Because a test that doesn't test "what happens when the enemy knows the weaknesses" is not a test.

Sure it is, if the opponent can't deploy effective counter-measures.

It doesn't matter if a protected drone is possible what matters is whether or not the opponent is capable of actually deploying protected drones. In a cat-and-mouse game all that is important is having an advantage for some period of time. It's not necessary to have the advantage persist indefinitely.

See: Russia's military being battered by very old technology every day in Ukraine, where in many cases counter-measures are well known but unavailable.

The drones would fly in a faraday cage? Really? Even if so, that's more cost and less weight they can carry. I am sure the US mil would also be concerned its own drones can be shot down like that.

A faraday cage protects against interference but does it shield against energy? Are they using microwaves to excite components in the drone or is it more like a MASER where microwave is used to deliver energy?

If this was light for example, I would equate what you are saying to coating the drones with a mirror, but if it is something like a LASER it would still damage the drone.

Conductive paints/coatings exist.

You've clearly never heard of building inspection drones. The drones fly in a sperical cage, which you can trivially run wires through, or over, to create a Faraday cage after programming the drones to fly whatever pattern you need them to. Hell, buy some copper tape, off you go.

Just because you didn't know about this thing, doesn't mean drone operators in military positions don't know about this either.

I did not know, I did not presume what military folks know either.

Military folks participate in drone competitions, and talk to R&D labs working with drones as well as civilian services that operate drones (mostly because the military itself also needs drones, and they need to stay on top of what's happening in the field). They know what's happening in this space, even if most other folks don't.

> You've clearly never heard of building inspection drones.

Maybe they haven't (also, you're being kind of aggressive here - why?) but I think most likely the people building these weapons have. Just because the article doesn't mention drones-in-Faraday-cages doesn't mean that the military are dummies who haven't thought about it / don't know anything about what kind of drones exist.

Eh, just responded in kind. The "Really?" to make it sound like I was talking out of my ass was as necessary as my "clearly".

Why do building inspection drones need a social cage?

I'm fairly certain that countermeasures could be had for a few grams of increased drone weight that wouldn't otherwise change the drone form factor or flight characteristics.

This is left as an exercise to the reader.

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