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What is peak gain?

If you have a strong LTE network, strong devices but a weak antenna, your signal will be inconsistent and you won't have the traction you need to reach peak speeds. Antenna gain is a popular statistic used to evaluate different antennas. Although higher gain is frequently thought to be better, this is not always the case.

dB(i)

Antenna gain is numerically expressed as a decibel value. The values you typically see are on a logarithmic scale, which means that for every 3dB increase in gain, the power increases by 2. This means that a 12dB antenna is not twice as potent as a 6dB antenna, but rather four times as powerful.

Antenna gain is typically expressed as a certain number of dBi rather than dB. Since this gain is isotropic—the i stands for isotropic—it is measured in relation to a theoretically perfect antenna. Obviously, this is oversimplifying. Unfortunately, antennas cannot precisely emit energy in the desired direction or directions in practice. This is so because the antenna's design greatly affects the radiation pattern. A high gain antenna with a poor radiation pattern may still have a high peak gain, but its performance may suffer due to a gain that drops off dramatically over frequency bands.

Gain

The amount of radio frequency that an antenna concentrates is measured by its gain. Let’s use the example of a flashlight to make it clearer. A lower gain antenna has a wider beam, similar to a flashlight. Because the energy is less concentrated, the light is less bright and has a less effective ability to penetrate shadows. However, a thin shaft of light that deeply penetrates shadows but doesn't cast much light out to the sides is produced when the beam is narrowed.
Antenna gain measures this exactly, how intense radiofrequency signals can be directed.

While directional antennas, perfect example of this flashlight analogy, omnidirectional antennas are not. These antennas emit signals in 360 degrees of space. As a result, the radiation pattern resembles a ring or a donut rather than a light beam. An omnidirectional antenna's gain can be increased to flatten the donut by basically pushing the "dough" farther out. This increases range in the horizontal plane but reduces the depth of the radiation pattern in the vertical plane.

Higher gain primarily results in the ability to reach a tower farther away, although positioning becomes more challenging. This makes sense for a directional antenna, however it operates a little differently with an omnidirectional antenna.
Consider an omnidirectional antenna on a ship at sea. If the gain is too high, the high-gain omnidirectional beam (the flat donut) will wave over a cell mast on the shore as it rolls from side to side due to waves. A lower gain antenna and a sailing closer to shore would be the answer in this case.