T-ETUL Radar feed?

[langelot]

I'm receiving periodically (very good) coverage from aircraft on the ground at LFPG LFPO EHAM and in a lesser proportion at EGLL. It has also a coverage over Switzerland and central France for enroute A/C. Because ETUL is Laarbruch in Germany, I'm wondering how they manage to do that? Well I have a small idea but the fact that it's almost only aircraft on the ground is pretty weird but interesting to get anyway...