Antenna Coaxial Cable - Grounding and Surge Protection

Due to the fact the communication tower beside the station acts as a lightning rod or sorts, it is important to keep any electrical charges that it receives outside of the building.  The tower structure combined with a tower grounding system normally helps to accomplish this; however, the nature of the tower’s purpose means that there will usually be a connection from the tower to the structure by way of the antenna’s coaxial cable.  This cable is highly susceptible to induced charges and is usually connected to a valuable piece of communication equipment which can be totally wiped out by surge, not to mention any other equipment connected to it or injury to the personnel using the equipment.  To reduce this exposure, any coax connected to an antenna that has been discontinued should be terminated outside of the building.  Active coax should have the outer shield of the cable grounded at the top and bottom of the cable run on the tower and before entry into the building, and the inner conductor of the cable should be connected to a grounded surge protection device (sometimes referred to by the brand name PolyPhaser) at or as near as possible to the point of entry.  The company servicing your radio equipment should be familiar with standard lightning protection measures for antennas, communication towers and coaxial cable, or you can contact a lightning protection company serving your area.  You may also want to have the servicing company verify that the tower legs are properly grounded since we could not visually verify this during my visit.