[Florin_Andrei]

That might work. The "cage" would be more like a sleeve in the region of the arm - just creeping out on the arm like a mesh tube (or even continuous foil tube) to protect the wires, electronics, and motors. A small hole would allow the motor hub to stick out of the cage, and the prop would be on top of that, outside the cage.

Heck, all the wires, electronics, and motors could be inside the "arm". Then coat that with some EM shield material (like a metal foil).

I like it.

Of course, from "like it" to "it's actually effective" there's still the nagging little field test to perform. It's the old shell-vs-armor game, since EM radiation has a penetration depth - Faraday cages are not magically 100% effective, make a thin enough one, and a powerful EMP would still do some damage inside. So now you need to carry thicker, heavier EMP armor.

[JoeAltmaier]

I think they are magically 100% effective. Unless the cage is breached, nothing will get through. However, an EMP pulse could melt holes in the foil.

However it also means the drone has no GPS; no wireless signaling; no sensors outside the foil at all. It becomes a dumbfire dead-reckoning device.

[Florin_Andrei]

> I think they are magically 100% effective.

No, they are not. Even a continuous, zero-hole metallic bubble will leak some radiation inside, depending on frequency, nature of material, wall thickness, etc.

Start here:

https://en.wikipedia.org/wiki/Penetration_depth

then continue reading about absorbance, skin effect, etc.

[JoeAltmaier]

I see. Only for zero-resistance metal would skin depth be zero.

[JoeAltmaier]

At microwave frequencies, skin depth is essentially zero (microns anyway) for most metals. So until the bag is melted, nothing will get through.