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17
ABOUT CE
INSTALLATION NOTES
• Compliance of base station transmitter installa-
tions with EN50385
The installation of this equipment and it’s associated
antenna should be made in such a manner as to re-
spect the EC recommended electromagnetic (EM) field
exposure limits. (1999/519/EC)
In order not to exceed these exposure limits it is nec-
essary to determine the ‘Compliance Boundary,’ that
means the volume within which the EM field radiated
by the transmitter/antenna installation may exceed the
1999/519/EC limits. You will then need to ensure that
members of the general public do not have access
within this area. The actual Compliance Boundary for
this repeater will be totally dependant on the antenna,
feeder, RF amplifier and other passive or active de-
vices used in the installation.
The RF output power of this repeater is 25 watts.
The figures contained in this guide are based on the
recommended limits for the general public and are ob-
tained by ‘worst case’ numerical analysis. For a defini-
tive evaluation of any given installation, measurements
should be made with an EM field meter and a broad-
band calibrated probe.
• Installation
The antenna should be installed as high as possible
for maximum efficiency and minimum EM field at
ground-level. The evaluation of radiated field should
take into account any additional RF amplifiers used,
any loss in the antenna feeder cable and the gain of
the antenna used as well as its polar radiation pattern.
If there are any objects or structures larger than half a
wavelength close to the antenna, or within the clear-
ance distances specified, then these can cause reflec-
tions which will have an effect on the overall radiation
pattern.
For any installation you need to consider ‘height clear-
ance’ (i.e. the height above any place where persons
may have access) and ‘front clearance’ (i.e. the dis-
tance in front of the antenna where the radiated field
may exceed the recommended limits). Normally with
an antenna installed on a reasonably high mast or
tower, there will not be any access point directly in
front but care should be exercised when there are
other buildings higher than the antenna within the
vicinity.
• Installation with a vertical type antenna at
VHF-UHF
You need to consider the distances between the an-
tenna and any point where persons may have access.
Allowing an average height of 1.8 m for a person in the
vicinity of the antenna the clearance distances can be
evaluated as follows. For the antenna a forward gain
of 1.6 and downward gain of unity has been assumed.
Power EIRP Distance
Height Front
clearance clearance
1 watt 1.6 watts 0.32 m 2.1 m 0.4 m
10 watts 16 watts 1 m 2.8 m 1.3 m
25 watts 40 watts 1.6 m 3.4 m 2 m
100 watts 160 watts 3.2 m 5 m 4 m
1 kW 1600 watts 10 m 12 m 13 m
• Installation with a yagi or directive type antenna
Exposure distance assumes that the predominant ra-
diation pattern is forwards and that radiation vertically
downwards is at unity gain (sidelobe suppression is
equal to main lobe gain). This is true of almost every
gain antenna today. Exposed persons are assumed to
be beneath the antenna array and have a typical
height of 1.8 m.
The figures assume the worst case emission of con-
stant carrier.
RF power Clearance heights by frequency band
Watts 10–2 m 70 cm 23 cm
13 cm
and above
1 2.1 m 2 m 2 m 2 m
10 2.8 m 2.7 m 2.5 m 2.3 m
25 3.4 m 3.3 m 2.7 m 2.5 m
100 5 m 4.7 m 3.6 m 3.2 m
1000 12 m 11.5 m 7.3 m 6.3 m
EIRP
Forward clearance, EIRP by frequency band
Watts 10–2 m 70 cm 23 cm
13 cm
and above
100 2 m 2 m 1.1 m 0.7 m
1000 6.5 m 6 m 3.5 m 3 m
10,000 20 m 18 m 11 m 7 m
100,000 65 m 60 m 35 m 29 m
