I don't know if you could ever stop a low cost drone short of using a shotgun. Even if you had some sort of directed EMP technology, the drone could position itself along the correct precomputed vector from far away, cut off electric, and glide the bomb to the target silently.
> the drone could position itself along the correct precomputed vector from far away, cut off electric, and glide the bomb to the target silently.
An octocopter/ordinary drone can't do this - their electric goes out and they fall from the sky.
For a glider you'd need an actual flyable airplane model (something like this: https://laughingsquid.com/a-15-foot-long-radio-controlled-ai...), and these are expensive as fuck - a single engine alone will run up well into four digit range, if not five digits (something like the JetCat P1000). And at that point, you could also go ahead and buy an outright RPG, should be far cheaper to acquire depending where you are, or buy a couple junker cars, load them up with fertilizer bombs, and distribute them where one expects the target.
ISIS used[1] the X-UAV Talon. This is a off-the-shelf 1.7M wingspan drone plane available for about $150 without electronics (which are around $50-$200 depending on how elaborate you want to get).
It's capable of 100km+ flights[3].
Here's a pic of one after being shot down in Iraq[4]
Reliably jamming drone comms would also jam all other radio based systems in the area. You could try to narrow your beam, but that could lead to evasive pattern dodge manouvers, and would be harder against a swarm of the things. Even then, the drones could get by with extremely crude, near ballistic autonomy (erraticly fly 500m in that compass direction and detonate on the moving blob near the pool).
INS chips providing enough precision for autonomous operation over last few kilometers are rather cheap nowadays too.
A small-ish plane frame could easily deliver a grenade from sleepy suburbs 10km straight to the Oval Office with only few minutes of warning (assuming somebody could actually detect it in time at all). We're just lucky nobody seems to be bothered to do that.
Well, if you managed to detect and track an incoming drone you could ‘jam’ its camera with a high-powered laser - or something that threw up a curtain of flares or burning magnesium, or whatever.
A drone swarm dropping hand grenades is like targeted artillery. Experience from WW 1 is that it's straightforward to defend against artillery fire, just retreat into a shelter. A target that's worth five dozen drones with grenades can afford a bunker.
