For a drone that is entirely stationary, this may work, but for specialized FPV drones that can go >100 km/h these are effectively useless. You can't hear it and you can't see it until it's already in proximity to you.
And this is only in relationship to consumer quadcopters. Actual UCAVs like the Bayraktar TB2 or LANCET you need something to the effect of a C-RAM and proper air defense system to get them out of the sky.
There is really only one defense to quadcopters and that is jamming the video transmit (VTX) and link between the drone and the operator,
if they are radio enabled. Because these drones are consumer drones using consumer hardware, there is a set frequency range of where they operate. While it's possible to have spread spectrum radio modules the cost / availability of these is not quite there to the extent of something like a out of the box like a DJI is yet.
The issue with jammers is a they are a radio that transmits continuously. You may as well be sending out a beacon saying "I'm here, look at me" to your adversary. And when your adversary has MLRS and artillery that's not a good thing. Russia has extensively used EW batteries for fire direction. And any modern military also has this capability.
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I think the only solution to quadcopters is some type of laser system. But whatever the solution is - it has to somehow be cheaper than the UCAV or quadcopter itself. I hope we do see one though because this has to be the most cowardly way to conduct warfare possibly ever.