I plan to install a Diamond X-200 antenna at this corner location, and I want to mount it directly on this angle steel.
Currently, we are considering how to address grounding issues. Is a 8-square millimeter tin-plated copper woven textile cable sufficient?
2.5 meters should be outside the lightning protection range of the building, but I'm still a bit uncertain. Does anyone have a better solution?

The cable can be directly run from inside the building to my house.
