Now I think I'll take a guess at how much a R9000 5kW wind turbine will produce. My guess it will produce a maximum of about 5kW?
I believe thats about 2 kettles...
Evance Wind - Small Wind Turbines
They are 18' (5.5m) diameter. Is that large enough to cause radar issues? It looks like they deal with individual turbines - not entire farms.
At a maximum of 25.5 meters high (about 70') - I suggest that these are unlikely to cause a problem to airfields unless they are put where late finals should be. You get trees much taller than that!