Sector antennas

As their name implies, sector antennas receive (and transmit) a signal from a specific sector. This sector is usually in the horizontal plane 60°, 90° or 120° and from 5° to 15° in the vertical plane.

Sector antennas are mainly installed on base stations by mobile operators or the mobile Internet, or they are used as part of repeaters. In order to have a signal at any point around the base station, the following antenna installations are used:

– 6 antennas with a radiation pattern (further RP) of 60°;

– 4 antennas with a RP of 90°;

– 3 antennas from RP to 120°.

A sector antenna in all working directions of its radiation pattern has approximately the same signal gain. This is the first difference between sectoral antennas and ordinary directional ones, whose RP has a pronounced maximum, falling to its borders.

A narrow RP in a vertical plane allows a sector antenna to receive (and transmit) a signal only from devices located on the ground surface and slightly above it. That is, the signal seems to "creep" along the surface, without creating unnecessary reflections from it and not irradiating the sky. In the usual directional antenna RP in the vertical plane will not allow to achieve this.

Imagine a building on the roof of which there are 6 sector antennas with a RP of 60°. These antennas are evenly spaced in a circle to turn the entire 360° around. This is how the signal propagation will look like if you look at this building from above:

And side view (only one antenna is shown):

At the subscriber, you can put either omnidirectional, or directional, or sector antennas. Advantage and disadvantage of each case:

1. Omnidirectional antennas

Advantage: the antenna catches the signal from all base stations located around, and the subscriber device connects to the least loaded base station with the most powerful signal level; simple installation of the antenna

Disadvantage: weak signal amplification (usually from 3 to 12 dB).

2. Directional antennas

Advantage: high gain allows you to achieve high speed, quality and stability of the connection; A narrow radiation pattern catches the signal only from the right direction and does not capture the side noise.

Disadvantage: when installing the antenna, you need to know the exact direction to the base station; if the base station fails or when it is heavily loaded, the subscriber unit will not be able to switch to another base station, you will have to manually redirect the antenna.

3. Sector antennas

Advantage: the gain comparable to directional antennas also allows to achieve high speed, quality and stability of the connection; RP in the form of a sector allows you to capture several base stations and switch between them depending on the communication conditions and the state of the BS.

Disadvantage: higher cost compared with directional and omnidirectional antennas (due, as a rule, their relatively low prevalence).

It is also worth noting that the sector antennas installed on the building do not pose a threat to the health of people in it. Sector antennas radiate all their power to the territory around them, and practically nothing is radiated down to the building itself. On the contrary, the reception of a signal in a building from the antenna installed on it will be much worse than on the territory next to them.