Understanding Antenna Gain and dBi

When buying an antenna there are a few aspects to consider to ensure you get the antenna that is right for you. Gain and dBi might sound confusing at first but are important considerations in choosing the right antenna. The gain of an antenna is simply the measure of an antenna’s ability to direct or concentrate radio frequency energy in a particular direction or pattern, with dBi being the unit of measure.

It is important to consider which gain is right for your application, and there are a few questions you can ask to determine this. Firstly, where will you be using your antenna? Is the terrain flat and expansive or hilly and rugged? Will it primarily be used for on-road use, or 4WDing? The answers to these questions can help point you in the right direction.

High gain antennas (8.1 dBi) take the signal and radiate it along a straight plane in a tight, narrow pattern. This is ideal where the terrain is quite flat with few obstacles in the signal path, such as when touring across the outback. Antennas  like GME’s AE4706/B or the AE4006 are both high gain 8.1 dBi antennas and are ideal for these uses.

A medium gain antenna (6.6, 5.1 dBi) has a more rounded, wider pattern than a high gain antenna. This means the signal is less likely to be obstructed by obstacles such as buildings, trees  or mountains. These factors make a medium gain antenna the best choice for those in suburban areas and the country side. The AE4705/B and the AE4018K1 are two of GME’s most popular medium gain antennas.

Unity gain (2.1 dBi) is a way of describing an antenna that outputs a signal at the same level at which it is input. The broad radiation pattern of unity gain antennas is less likely to be obstructed by buildings, bushland and hilly terrain. Therefore, a unity gain antenna is the best choice for rugged and hilly country. The AE4704/B is the ideal antenna choice for the rough terrain often encountered when 4WDing. The AE4704B is also available in a specifically designed 4WD pack, paired with GME’s venerable UHF CB radio, the XRS-370C (XRS-370C4P).