@graydon @cstross Some of the anti-drone solutions evolving in the Ukraine conflict are distinctly low tech, like dangling chains from your tank for the drone to bump into... https://www.rferl.org/a/anti-drone-evolution-ukraine-war-russia/33020303.html
@m @cstross Drones are a way to convert manufacturing capacity into dead enemy soldiers (useful) and reconnaissance (vital).
It's really unlikely there's an effective passive counter; armour exists to get knowledge about how you fucked up off the battlefield. It isn't ever going to provide a functional counter to reconnaissance.
Aka, drones are expendable cavalry. (That IS new; cavalry is traditionally a scarce, expensive, prestige asset.) All the traditional cavalry things apply.