The choice of antennas for
base stations rarely receives any attention. Antennas are regarded as a
cheap commodity that will "do its job" regardless of which antenna you
choose.
Nothing could be further from the truth. Antennas have a tremendous
impact on coverage, performance, capacity and efficiency, and choosing
the right ones can make or break a mobile operator's ability to cope
with the rapidly increasing demand for data.
Looking at the installed base, one could get the impression that the
obvious, or even optimal, choice for almost all sites would be the
traditional 18 dBi antenna.
This antenna has 65° of horizontal beamwidth and around 6.5° of vertical
beam width, as do about 80 percent of all installations on 1,700 to
2,100 MHz.
The 15 dBi antenna is still quite common, especially on the lower frequencies, with a vertical beam width of around 14°.
There are also high gain 21 dBi antennas and new so-called ultra
high-efficiency antennas using air as dielectric and virtually
eliminating power losses.
These antennas improve base stations' transmission capacity, resulting
in higher signal strength, an increase in geographical area coverage,
improved indoor penetration, increased traffic, improved data throughput
and reduced production costs per call.
One newly launched multiband antenna (by Swedish manufacturer CellMax
Technologies) offers 21 dBi radiated power on the high band with 4° of
vertical beam.
18 dBi antenna is chosen for historical reasons, not with forethought
