Icom IC-7610 Instruction Manual basic - Page 77

INSTALLATION NOTES For amateur base station installations it is recommended that the forward 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 30 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, the antennas may be physically short in terms of electrical length and that the installation will require some antenna matching device which can create local, 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. The EC recommended limits are almost identical to the FCC specified 'uncontrolled' limits and tables exist that show pre-calculated safe distances 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 radiation pattern is forward 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 a constant carrier. For the bands 10 MHz and higher the following power density limits have been recommended: 10-50 MHz 2 W/sq m Vertical clearance by EIRP output 1 Watts 2.1 m 10 Watts 2.8 m 25 Watts 3.4 m 100 Watts 5 m 1000 Watts 12 m Forward clearance by EIRP output 100 Watts 2 m 1000 Watts 6.5 m 10,000 Watts 20 m 100,000 Watts 65 m In all cases any possible risk depends on the transmitter being activated for long periods. (actual recommendation 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 emission, i.e., SSB, CW, AM etc. have a lower 'average' output power and the assessed risk is even lower. ••List of Country codes (ISO 3166-1) Country Codes Country Codes 1 Austria AT 18 Liechtenstein LI 2 Belgium BE 19 Lithuania LT 3 Bulgaria BG 20 Luxembourg LU 4 Croatia HR 21 Malta MT 5 Czech Republic CZ 22 Netherlands NL 6 Cyprus CY 23 Norway NO 7 Denmark DK 24 Poland PL 8 Estonia EE 25 Portugal PT 9 Finland FI 26 Romania RO 10 France FR 27 Slovakia SK 11 Germany DE 28 Slovenia SI 12 Greece GR 29 Spain ES 13 Hungary HU 30 Sweden SE 14 Iceland IS 31 Switzerland CH 15 Ireland IE 32 Turkey TR 16 Italy IT 33 United Kingdom GB 17 Latvia LV 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 I