Earthing, bonding and protection of radio base stations

Radio base stations (RBS), especially in rural areas, are often located on top of hills and mountains in order to get as good coverage as possible. The towers with antennas are therefore a perfect target for lightning strikes and special attention must be paid to earthing, bonding and protection of these sites for the safety of personnel, and to prevent expensive damage and lost communication. Of the more than 100000 installed Ericsson RBS-sites world wide, we can estimate that about 2-5% of the sites will suffer damage from different kinds of atmospheric disturbances. In some countries this figure can be much higher and therefore it is of utmost importance to have a reliable site protection. The damage can be related to either direct lightning strikes or coming in from the AC mains supply which may result in lost communications. This paper describes some of the nature of lightning and atmospheric disturbances that occur on sites in lightning exposed areas and also cover examples of solutions for special “problem” sites and how to protect equipment supplied by different kinds of public AC-mains supplies. The importance of, and how to create, a reliable strong equipotential environment for all equipment installed on the radio base station is also described. The conclusion shows the basic site requirements that always ought to be implemented, and also some examples of extra equipment that it might be necessary to install in places with special problems or extraordinary circumstances