What is the antenna gain?

Antenna gain is the ratio of the power density of the signal produced by the actual antenna at the same point in space as the ideal radiating element, under the condition of equal input power. It quantitatively describes the extent to which an antenna concentrates the input power.

The gain is obviously closely related to the antenna pattern. The narrower the main lobe of the pattern, the smaller the side lobes and the higher the gain. Antenna gain is a measure of the ability of an antenna to transmit and receive signals in a particular direction. It is one of the most important parameters for selecting a base station antenna. In general, the increase in gain is primarily dependent on reducing the width of the lobes that are perpendicular to the radiation, while maintaining omnidirectional radiation performance on the horizontal plane. Antenna gain is extremely important to the quality of the mobile communication system because it determines the signal level at the edge of the cell. Increasing the gain can increase the coverage of the network in a certain direction or increase the gain margin within the determined range. Any cellular system is a two-way process that increases the gain of the antenna while reducing the gain of the two-way system gain budget.

There are two types of antenna gain: dBi and dBd, where dBi is the reference of the ideal point source antenna, and the radiation in all directions is uniform; dBd is based on the half-wave array (dipole) antenna. The reference, the gain dBi = dBd + 2.15 with respect to the symmetric array antenna. Under the same conditions, the higher the gain, the farther the distance the wave travels.