DC-Grounded Antennas

Prefer DC-grounded antennas because they do not build up static electricity. If you must use a non-DC-grounded antenna, use an inductor-type arrestor with it.

A DC-grounded antenna displays a short when an Ohmmeter is connected between the center conductor and shield of the connector. Examples of antenna types which are DC-grounded include folded dipoles and shunt fed Yagi antennas. An advantage of DC-grounded antennas is that they do not build up static electricity since the charge is shunted to ground.

A non-DC-grounded antenna displays an open when an Ohmmeter is connected between the center conductor and shield of the connector. Many common collinear ground plane antennas are not DC-grounded. This includes the Comet CX-333 antenna used at our county network radio sites and at many EOCs.

Gas discharge tube arrestors should not be used with non-DC-grounded antennas, because they will allow static electricity to build up in the antenna, resulting in extra noise. When the static build up is high enough, the gas discharge tube will fire and short the static to ground. Some transients can occur at the equipment during discharge. The constant cycle of static build-up, followed by discharge, followed by build-up will prematurely age the gas discharge tube, potentially leaving the equipment unprotected.