To minimize damages in case of a lightning strike, both bases of the antennas are connected to the steel roof construction via a 2x20mm2 ALU strip on concrete
You here can see the artificial ground surface. It consists of 2 cheap rolls 1x25m powder coated galvanized garden fence
grid It is electrically connected to the grounded antenna bas. It is meant to try to shield the antenna from (PLC) noises coming from the apartments below.
With regular intervals ferrite clamps are placed on the cables In the concrete roof beneath them run noisy mains cables. These clamps prevent these noises to run
towards the antennas or the radios. If the distances between clamps is kept small, they also prevent induction from, and re-radiation of transmitted signals. The radiation
patterns of the antennas then are not influenced.