Drones dont show up on radar as they are mostly plastic.
Picture on a news website shows just the red and green running lights.
Easy way to cause chaos.
350 euro would get you drone witb 25 min endurance and 2km range, 60kph speed and gps features.
The person could buzz the airport for a while and fly it back, swap the battery and then return a few minutes later.
I have 3 batterys for my main one snd regularly keep it up for over an hour if the weather is good.
Jammers exist to block their control signals but these might interfere with other airport systems.
Birds of prey have been trained to catch them but is risky for the bird.
Best way to take these down is to use another drone but armed with a device that will project something to disrupt their props.
Even in daytime drones are a bit too high for a shotgun and a rifle would need a lucky shot.