I had one problem with the Homematic CCU2: The radio range.
Some actors or sensors kept having connection issues and some others simply were out of the radio range. The goal was to get a power adapter connected 2 levels under our apartment and get rid of all those warning messages.
Cosnidering the small antenna of the Homematic CCU2 in the below pictures (yes, this tiny black thing is the antenna), it was clear what could be optimized.
While researching for radio range optimization I stumbled upon https://www.stall.biz
A great page describing various approaches on how to optimize the radio range with differnt kinds of antennas. You can also buy the parts there and DIY. I decided to go with the flat antenna as it promised to be most effective for the desired purpose.
The following page includes some information about the flat antenna and also a comparison with other DIY antennas:
Find below pictures of my “modification”.
The result is amazing!
I really got rid of those warning messages and I finally can reach sensors and actors in the basement allowing me to implement new use cases 🙂