Antenna HO and sectorized Grid

Antenna HO and sectorized Grid

Two lobes (radiation maxima) :The main lobe in the front direction should be maximised and the back lobe should be minimised. Sites are often configured with three cells where each cell represents a 120° sector. This sector width is not the same as the half power beamwidth (-3 dB point) for the antenna used. An antenna with 65° half power beamwidth is often used in a 120° sector.

A radiation pattern on top of a hexagon. The distance from the site to the cell border along the 120° line is half the distance from the site to the cell border in the front direction (“R” compared to “2R”).

As the antenna only needs to cover half the distance along the 120° line it roughly needs 10 dB less gain in that direction. This means that a three sector site needs antennas with a -10 dB beamwidth of 120°. Such an antenna normally has a -3 dB beamwidth of 60° - 65° (the value which is specified by the manufacturer).