OK, Berlin is 480 Km away. But why be negative?? It is only 300 Miles
Anyway, I have included the colour –dish-dish size legend to the map Rolf has posted earlier.
From that it is clearly visible that Berlin needs a dish much bigger than mine. But Dusseldorf should not be a problem, it is on Latitude 51.3 North and Longitude 6.7 east. Just to compare, I am on 50.5 north and 7.3 east. The dish size I got is 66 x 57 cm offset, and the signal strength I get on the D 100 is between 75-80%. Looking at the map, I am inside the green area (75CM dish)
Even though the footprint map is not very clear, you can more or less draw an arc starting from Saarbrücken in the south, towards Koblenz-Dortmund-Oldenburg. Everything west from that should not have a problem. Anything east of that, still no problem but bigger dish.
The one thing that I noticed being in the “Green” area is that I should have a 75 cm dish, but mine is smaller- still get excellent reception. This would also explain why Berlin can use a 120 Dish, even though on the footprint it is not even on.