> You’ll need vastly expanded radar coverage to detect drones flying too high to be detected by camera.

I’d actually argue it’s not possible with current radar tech. The radar signature of most consumer drones is so small that if you had radar tuned to that size, you’d be getting false positives all the time. Even in the bigger drones, there’s still a very small radar signature too. I’ve not tested it, but even my 6’ wide dual octocopter likely wouldn’t even be identified on radar.