The enemy could be hiding precisely at the windmills /s

Perhaps if tip speed is X and radar installation is perpendicular to wind turbine, then an enemy can approach at speed X in the turbine's radar shadow. There would still be multiple pulses with timing differences but if there's a field of turbines then I'd guess there's enough interference/scatter to be a problem. Like using approaching from the sun causes problems for pilots.

The reflections from the turbines would pulse due to the blades so in theory their scatter could be cancelled out in processing?