This is part 4, the final technical note about grounds. This time we’ll look at antenna grounds. Since a lightning strike can generate several hundred thousands of volts, you want a good antenna ground system to dissipate the voltage and current before it reaches you or your equipment.

The most important factor in determining your antenna ground system is it’s location. Since a lightning strike will leave a dearth of electron on your antenna and like charges repel you want to get these into the ground as quickly as possible. However, the ground will generally become saturated within 50 to 75 feet and be unable to absorb any more electrons. Thus, it is a good idea to locate your antenna at least 50 to 75 feet from the ham shack.

Your antenna support should not be made of non-conductive material such as wood. Only use metal towers to support your antenna. Crank-up or push-up antenna supports should have jumpers across their joints with short pieces of copper strapping. Self support towers do not need these jumpers.

The least expensive way to construct your ground system for the antenna is to use ground radials (see figure below).

These radials should be at least 50 feet long and connected to ground rods . The ground rods should be spaced twice their length apart, that is 8 foot ground rods should be spaced 16 feet apart along the length of the radials.

Finally, if necessary, dope the ground in the same manner as discussed in the previous article to obtain a good earth ground.

Last updated on March 30, 2006