How to Ground an Antenna: aerial earthing

The antenna ground or earth system can be key to its operation whilst also being a key safety feature.

Antenna Grounding Includes:
How to ground an antenna     Antenna RF ground     Antenna ground plane    

Knowing how to ground or earth an antenna system can be a key factor in the operation of some antennas.

Knowing how to ground an antenna properly can make significant improvements to its performance, whereas a poor ground or earth connection can mean that its performance is greatly impaired.

Grounding an antenna properly makes the antenna safe to use and also enables the best to be made of the performance of the antenna.

Earth or ground circuit symbol

How to ground antenna

There are several aspects to grounding an antenna. When looking at how to ground an antenna it is necessary to look at what is required and then proceed accordingly:

  • How to ground an antenna for RF performance:   Some types of antenna are unbalanced and are designed to operate with a ground connection to enable them to operate correctly. Balanced antennas like dipoles do not need an RF ground for their correct operation as long as common-mode currents are kept off the feeder. However many vertical antennas and many end fed wires use their RF earth connection as an integral part of the antenna. For system like these it is imperative that a good ground connection is made.
    • Physical grounded earth system:   The physical RF ground system is made by making direct contact with the ground. As conductivity of the ground is relatively low, a good surface area must be presented by the conductor to the ground. The volume in which conduction can take place is huge, and therefore once a good connection has been made to the ground, the actual resistance can be low even though the resistivity of the ground material is high.     . . . . .Read more about the antenna RF ground.
    • Ground plane:   Many vertical antennas employ what is called a ground plane. This is a simulated ground made from a sheet of conductor which typically extends out to a quarter wavelength from the antenna. Often the conductor is simulated by a number of radials, often a quarter wavelength long.     . . . . .Read more about the antenna ground plane.
  • How to ground an antenna for safety:   An antenna is a metallic object that can sometimes be in danger of becoming live. It could be as a result of being connected to equipment that becomes defecting and puts a live voltage onto the antenna. It could be as a result of the accidental of live power lines. These have all happened in the past and could be a danger.
  • How to ground antenna for lightning:   The occurrence of lightning is a fact of life. There are many dramatic photographs of lightning striking tall buildings or even just striking the ground. The lightning strike can have a very destructive effect. With typical current levels rising to anywhere between about 3 000 and 140 000 amps, it is hardly surprising that anywhere that receives a direct strike is damaged. Even if a direct strike is not experienced, induces voltages can be very high.
    Lightning strike
    A lightning strike
    Photo taken from top of Petronas Towers in Kuala Lumpur Malaysia

Whatever the reason for needing to ground an antenna, there are many instances where this is required. When grounding an antenna it is necessary t undertake it knowing how to ground the antenna properly.

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