Huawei DBS3900 Installation Manual page 116

1.3 Electromagnetic Field Exposure
Introduction
The Base Transceiver Station (BTS) emits Radio Frequency (RF) radiation. Follow the local
safety regulations when installing and operating the BTS to avoid radiation hazard.
Location of Base Station Antennas
Base station antennas, the source of the radiation, are usually mounted:
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Generally, the antenna cannot be located in a position lower than 10 m. The energy usually
forms a horizontal main beam and is slightly tilted downwards. The remaining energy forms
into weaker beams on both sides of the main beam. The main beam, however, does not reach
the ground if the antenna is around 50–200 m away from the ground.
The highest level of emission would be expected in close vicinity of the antenna and in line of
sight to the antenna.
Exclusion Zones
The requirements for exclusion zones are as follows:
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Guidelines on Choosing Antenna Sites
The guidelines on choosing the antenna sites are as follows:
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Issue (02)
On freestanding towers, with a height up to 30 m
On a tower on the top of buildings
To the side of buildings, on rare occasions
The antenna should be properly located to prevent the public from accessing the area
where the RF radiation exceeds the previously mentioned limits.
If areas with excessive RF radiation are accessible to the operation and maintenance
(O&M) personnel, ensure that they know the source of radiation and can power off or
shut down the transmitters before entering high radiation areas. In addition, such areas
must be confined within a distance of 10 m from the antennas.
Each exclusion zone should be defined by a physical barrier and by a recognizable sign
warning the public or O&M personnel.
For roof-mounted antennas, raise the antennas above the height of the personnel who
may have to work on the rooftop.
For roof-mounted antennas, keep the transmitter antennas away from the areas accessible
to the public, such as roof access points, telephone service points, and HVAC devices.
For roof-mounted directional antennas, place the antennas near the periphery, and do not
make the antennas face the building.
Consider the trade-off between large aperture antennas (lower maximum RF) and small
aperture antennas (lower visual impact).
Keep higher-power antennas away from accessible areas.
Keep the antennas in a site that is far away from urban areas, though this may contradict
the coverage area requirements.
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