antenna gain information

Why is the antenna important?

An antenna is a device for transmitting and/or receiving signals – the ‘ears’ of your communication system. A good antenna is designed to be
‘in-tune’ to the signal you are seeking – your phone or radio ‘hears’ the signal, and you hear a clear signal. Use a poor antenna and you simply cannot communicate effectively.

Antenna radiation patterns and gain

In a perfect world, mobile antennas should radiate in a symmetrical pattern 360-degrees around the antenna/vehicle, however, this can only be achieved by mounting the antenna high in the middle of the vehicle’s roof. The next and most popular alternative is the purchase of a ground-independent antenna. While other mounting positions (i.e. side of roof rack, guard, or bull bar) will affect the pattern, purchasing a ground-independent antenna and mounting it as high as possible on your vehicle will minimize the pattern distortion. Antenna gain is the ability of the antenna to radiate more or less in a direction compared to a theoretical/known antenna. In a mobile situation, the gain you want may depend on the terrain you are driving in. As the gain is increased, the radiation gets compressed into a thinner pattern and reaches out further to the sides. 

Antenna Applications

A thinner radiation pattern may prevent a strong signal reception when driving through hills and valleys, or amongst built-up areas, such as city centres, where base station antennas tend to be located on top of buildings. 

In summary, the ideal gain for each situation is as follows:

• Low gain antennas (2-3 dBi) are good for hilly terrain but can lack range in flat terrain.
• Medium gain antennas (5-6.5 dBi) are good all-round antennas which work well in hilly and flat terrain.
• High gain antennas (8+ dBi) are good in flat terrain but poor in hilly terrain