Icom IC-910H Instruction Manual Download Page 84

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INSTALLATION NOTES

For amateur base station installations it is recommend-
ed that the forwards clearance in front of the antenna
array is calculated relative to the EIRP (Effective Iso-
tropic 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 recommend-
ed for different frequencies, a relative table shows a
guideline for installation considerations.

Below 30 MHz, the recommended limits are speci-
fied in terms of V/m or A/m fields as they are likely
to fall within the near-field region. Similarly, the an-
tennae may be physically short in terms of electrical
length and that the installation will require some an-
tenna matching device which can create local, high in-
tensity magnetic fields. Analysis of such MF installa-
tions is best considered in association with published
guidance notes such as the FCC OET Bulletin 65 Edi-
tion 97-01 and its annexes relative to amateur trans-
mitter installations. The EC recommended limits are al-
most identical to the FCC specified ‘uncontrolled’ limits
and tables exist that show pre-calculated safe distanc-
es for different antenna types for different frequency

bands. Further information 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 vertical-
ly 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 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 have been recommended:

10–400 MHz

2 W/sq m

435 MHz 2.2 W/sq m

1296 MHz 6.5 W/sq m

EIRP Clearance heights by frequency band
Watts 10–2 m 70 cm 23 cm 13 cm and above

1 2.1 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

Forward clearance, EIRP by frequency band
Watts 10–2 m 70 cm 23 cm 13 cm and above

100

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

In all cases any possible risk depends on the trans-
mitter being activated for long periods. (actual recom-
mendation limits are specified as an average during 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 assessed
risk is even lower.

Versions of the IC-910H 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 condi-
tions 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.

• List of Country codes (ISO 3166-1)

Country

Codes

1 Austria

2 Belgium

3 Bulgaria

4 Croatia

5 Czech Republic

6 Cyprus

7 Denmark

8 Estonia

9 Finland