Do you mean a civil airfield that takes private aircraft or a private airstrip?
The Germans are a bit more rule-bound than UK in that one need permission to establish a private airstrip, in the UK one can just do it.
The result of this is airstrips are not as common, I can see some on Google earth 10-14 miles away. I have no contact details.
I'm sure someone will be along shortly with a web site for this.