How to Ground an Antenna Mastby David Lipscomb
In any electrical circuit -- or anything involving electricity at all -- a proper ground is required. In the case of antennas, proper grounding is for constant bleeding of small static charges that continually build, shunting them safely to prevent static discharge. Grounds also help mitigate the effects of surges, which can wipe out your TV, DVR, shortwave radio or anything else connected to the array.
It's the Law
Regardless of whether you think it's necessary to properly ground an antenna, building codes have a say. Depending on where you live, you might get a notice for an inspection of your property for proper code compliance. Chances are, this will occur if your antenna attracts sufficient attention, such as a large HAM radio array. Failure to improperly ground an antenna might have insurance implications, since a claim could be denied if the problem pointed to an improperly grounded mast.
How to Ground
You'll need to have a ground wire of sufficient gauge -- usually around 8 gauge or more -- firmly attached to a cold water pipe or metal rod hammered at least 6 feet into the ground. Never use a natural gas pipe for this ground for obvious reasons. If you are using an existing cold water pipe, it's important that at least 10 feet of metal pipe exists below ground after the ground point -- an important consideration, since many such pipes are attached to PVC at some point inside or outside the structure. You need to remove any paint or coating on the pipe to ensure a proper ground. The wire is attached via a clamp that surrounds the pipe or rod, with the wire attached to the clamp with a set screw. Lightning arrestors may also be used in conjunction with proper grounding, aiding in static charge drain or surge. One arrestor must be placed at each end of the wire and UL-certified.
Although every antenna has a provision to route a separate ground wire, it's also wise to use a ground block to protect downstream devices against surge with the coaxial cable itself. These are inexpensive metal devices, featuring threaded connectors. Like other ground blocks, this must be connected firmly to a rod or pipe. You can also place this block at or near an electrical panel to access the structure's common ground, potentially avoiding interference and ground loops. Consult an electrician if you're not sure about working around a panel. Screw the coaxial wire from the antenna to the block and then screw another coaxial cable from the opposite side of the block onto your electronics.
Antennas are used in mobile environments as well, such as in CB applications. In these cases, the metal chassis of the vehicle serves as the ground plane, shunting noise and small spikes safely away from connected electronics. The radio or electronic device is grounded to the common ground or, in lieu of this, a solid piece of sheet metal away from weld points. In mobile applications, the vehicle's chassis is not only the ground, but comprises half of the antenna's operation for receiving and broadcasting. Boats and cars with high fiberglass content use specialized antennas that do not require a ground plane, although a grounding block located near the battery is still desirable.