Antenna gain explained

An antenna is an electrical device that receives electrical current and converts it to a radio wave, used for transmitting and receiving voice and data.

Antennas are made of conductive metals such as gold, silver, copper, aluminum and steel. They’re also typically wrapped in an insulator such as hard rubber or plastic. These materials in themselves cannot create power from the current the antenna receives, but rather are able to conduct.

The following are some terms that illustrate how the antennas on your TP-Link network device work.

Definitions

Decibel (dB)
This is the unit of measure of loss or gain. This value represents the ratio between two amounts of electrical or acoustical power received. In basic terms, it’s a measurement of power.

Decibel-isotropic (dBi)

This is a hypothetical reference point where an isotropic antenna transmits a signal in a perfect sphere. It should be noted that a perfect sphere is impossible to create so 0Dbi is a realistically impossible number.

Antenna Gain
Also simply known as ‘gain’, this is a measurement of power that represents the efficiency in which the antenna converts electricity into radio waves. When speaking in terms of antennas:

Gain + dB = dBi of an antenna

The gain can affect the direction in which the antenna operates. The higher the gain, the more directional the antenna is. The antennas power doubles for every 3dBi.

Radiation Pattern
This is a graphical representation of signal emitted from the antenna. In simple terms, it represents if your Antenna is directional, Bi-directional, or Omni-directional.

Radiation Angle
This is the beamwidth of the antenna. It has a horizontal and vertical number in the unit of degrees. This number indicates the area of coverage where the radiation pattern is emitting.

For example, if a TP-Link outdoor access point TL-WA7510N has a directional antenna with a radiation angle of 60 degrees horizontal and 15 degrees vertical, this means the receiver endpoint must be at the same angle to receive a signal. This becomes very important when setting up an extended wireless network.

Coverage
This is the physical area in which a signal can still be received and transmitted. In general, the more powerful an antenna is, the more coverage it provides. However, the more powerful an antenna is, the more directional the signal becomes as well.

In Closing

Antennas do not create power, but rather converts it to a useable RF radio signal. The power or gain will determine the general distance and direction your antenna will achieve. The higher the power gets, the lower the beam width becomes.