ABOUT CE
6
INSTALLATION NOTES
• Compliance of base station transmitter installa-
tions with EN50385
• Installation with a vertical type antenna at VHF-
UHF
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)
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 for-
ward gain of 1.6 and downward gain of unity has been
assumed.
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.
Height
clearance clearance
Front
Power
EIRP Distance
1.6 watts 0.32 m
1
1 watt
2.1 m
2.8 m
3.4 m
5 m
0.4 m
1.3 m
2 m
2
10 watts
25 watts
16 watts
40 watts
1 m
1.6 m
3.2 m
10 m
3
100 watts 160 watts
1 kW 1600 watts
4 m
12 m
13 m
4
The RF output power of this repeater is 25 watts.
5
The figures contained in this guide are based on the
recommended limits for the general public and are
obtained by ‘worst case’ numerical analysis. For a de-
finitive evaluation of any given installation, measure-
ments should be made with an EM field meter and a
broadband calibrated probe.
• 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.
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7
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• Installation
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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.
The figures assume the worst case emission of con-
stant carrier.
10
11
12
13
14
15
16
17
18
19
20
21
RF power Clearance heights by frequency band
13 cm
and above
Watts
10–2 m
70 cm
23 cm
If there are any objects or structures larger than
half a wavelength close to the antenna, or within the
clearance distances specified, then these can cause
reflections which will have an effect on the overall ra-
diation pattern.
1
10
25
2.1 m
2.8 m
3.4 m
5 m
2 m
2.7 m
3.3 m
4.7 m
2 m
2.5 m
2.7 m
3.6 m
7.3 m
2 m
2.3 m
2.5 m
3.2 m
6.3 m
100
1000
12 m 11.5 m
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 vi-
cinity.
EIRP
Forward clearance, EIRP by frequency band
13 cm
Watts
10–2 m
70 cm
23 cm
and above
0.7 m
3 m
100
1000
10,000
100,000
2 m
6.5 m
20 m
65 m
2 m
6 m
18 m
60 m
1.1 m
3.5 m
11 m
35 m
7 m
29 m
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