[tejon]

Frequencies are heavily regulated in the US as well. There are a handful of public bands, but anything else requires FCC licensing to use. Broadcast power is also restricted.

Of course, Germany could still be more restrictive, I don't know the law there! But there must be a fairly simple licensing path for some microwave bands, or nobody would be able to sell wireless routers. This is the same general class of equipment, so unless there's too much restriction on broadcast power to connect at kilometer+ ranges (with a focused directional antenna, rather than the broadcast antenna of a router!) there should be a way to make it work.