Originally Posted by
_Agrajag_
For surveillance and air traffic type radars that's true, there's a Doppler limit set to ignore slow moving stuff to get rid of clutter. However, drones can fly very slowly and I doubt the plastic propellers give much of a return. My guess is that an air defence radar has to have the ability to detect a target with very low, even no, relative motion with respect to the radar.
The old Met radio sonde people derived some great spectaculars ..... the big balloons had a decent payload, reflector was standard issue, fuses and explosives easily improvised ....so give low buoyancy, low rate of climb, long fuse and the right wind direction. sirens every night in Moscow, cost peanuts.
I might even be pursuaded to come out of retirement.