Radio Station Grounding

There are three types of ground systems to be considered within a radio station environment:

1) Safety Ground
This ground is simply the AC power neutral system, formed by a single driven ground.  This is found in most residential installations.  Some electrical codes still allow a connection to a cold water pipe.  This seems to be going out of style with the installation of PVC or other “non-conductive” carriers of water. Never chop off or isolate the 3rd pin ground on any power supply or other equipment.  It is there to prevent electric shock in the event a component fails.

2) Lightning Ground
This ground is found on most antenna support structures (towers), buildings and other tall structures.  Several ground rods are driven and spaced equally around the base of the tower.  These ground rods must be connected to each other as well as the tower in the form of a ring or circle.  The spacing should be about 2 - 2.5 meters.  All conductors must be attached using the lowest possible resistance connection possible (i.e. crimp, clamp and cad-weld).  The goal is during a lightning strike the energy is dispersed to as large an area as possible.

3) RF Ground
The station ground must provide both an effective DC and RF ground.  Creating a good DC ground is not a problem, but an effective RF ground must be carefully planned.
Bonding Grounds
All grounds should be bonded together !

This includes a house ground, exterior antenna tower ground and station shack ground. This “bonding” should occur at a single point ground (SPG) located immediately outside the structure (house or operating location). During a nearby lightening strike the energy is dispersed over a wide area (several thousand feet in all directions). Should there be two driven grounds in the area, a “step voltage” is produced and these grounds are not at the same potential.

Allowing a difference in potential will allow large currents to travel from one point to another. The path between the two separate grounds may be through the house electrical system or radio equipment causing damage and danger to the radio operator.

The various ground connections in the shack (shown above) must be grounded to a SPG (single point ground) in the radio room.  Connections which leave the radio room and cross the line shown in RED must be protected.  This can be accomplished via lightning arrestors or other surge suppression methods at the bulkhead (as they enter the house/structure)  Following these basic rules prevents noisy ground loops or a dangerous difference in electrical potential during a lightning strike event. 

The radio room SPG should then be bonded to the exterior SPG at the entrance bulkhead into the building. (see below)