Instruction manual

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60
INSTALLATION NOTES
For amateur base station installations, it is
recommended that the forwards clearance in front of
the antenna array is calculated relative to the EIRP
(Effective Isotropic Radiated Power). The clearance
height below the antenna array can be determined in
most cases from the RF power at the antenna input
terminals.
As different exposure limits have been recommended
for different frequencies, a relative table shows a
guideline for installation considerations.
Below 10 MHz, the recommended limits are specified
in terms of V/m or A/m fields as they are likely to fall
within the near-field region. Similarly, at antennae may
be physically short in terms of electrical length and that
the installation will require some antenna matching de-
vice which can create high intensity magnetic fields.
Analysis of such MF installations is best considered in
association with published guidance notes such as the
FCC OET Bulletin 65 Edition 97-01 and its annexes
relative to amateur transmitter installations. Further in-
formation can be found at http://www.arrl.org/
• Typical amateur radio installation
Exposure distance assumes that the predominant ra-
diation pattern is forwards and that radiation vertically
downwards is at unity gain (sidelobe suppresion 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 to 1.8 m.
The figures assume the worst case emission of con-
stant carrier.
For the bands 10 MHz and higher the following power
density limits are recommended :
10–30 MHz 2 W/sq m
Watts (EIRP)/ Clearance heights
1 2.1 (m)
10 2.8
25 3.4
100 5
1000 12
Watts (EIRP)/ Forward clearance
100 2 (m)
1,000 6.5
10,000 20
100,000 65
In all cases any possible risk depends on the transmit-
ter being activated for long periods. (actual recom-
mendation limits are specified as an average of 6
minutes) Normally the transmitter is not active for long
periods of time. Some radio licenses will require that a
timer circuit automatically cuts the transmitter after 1–2
minutes etc.
Similarly some types of transmitter, SSB, CW, AM, etc.
have a lower ‘average’ output power and the perceived
risk is even lower.
Versions of the IC-718 which display the “CE”
symbol on the serial number seal, comply with
the essential requirements of the European
Radio and Telecommunication Terminal Direc-
tive 1999/5/EC.
This warning symbol indicates that this equip-
ment operates in non-harmonised frequency
bands and/or may be subject to licensing con-
ditions in the country of use. Be sure to check
that you have the correct version of this radio or
the correct programming of this radio, to com-
ply with national licensing requirement.
IC-718.qxd 02.9.6 14:30 Page 60