Planning wireless systems
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8.10 Free space attenuation
When using wireless transmission technology, the signal between the transmitter and
receiver is attenuated by the air. The following table lists attenuation values for different dis-
tances with a free Fresnel zone.
Table 8-6 Free space attenuation
Distance Attenuation at 2.4 GHz Attenuation at 868 MHz
5m -54dB ...
10 m -60 dB ...
20 m -66 dB ...
30 m -69.5 dB ...
50 m -74 dB ...
100 m -80 dB -71.2 dB
110 m -80.8 dB ...
120 m -81.6 dB ...
150 m -83.5 dB ...
200 m -86 dB -77.2 dB
250 m -88 dB ...
300 m -89.5 dB -80.7 dB
350 m -90.9 dB ...
400 m -92 dB -83.2 dB
450 m -93.1 dB ...
500 m -94 dB -85.1 dB
550 m -94.8 dB ...
600 m -95.6 dB -86.7 dB
650 m -96.3 dB ...
700 m -96.9 dB -88.1 dB
750 m -97.5 dB ...
800 m -98.1 dB -89.2 dB
850 m -98.6 dB ...
900 m -99.1 dB -90.3 dB
950 m -99.6 dB ...
1000 m -100 dB -91.2 dB
2000 m - -97.2 dB
3000 m - -100.7 dB
4000 m - -103.2 dB
5000 m - -105.1 dB
6000 m - -106.7 dB
7000 m - -108.1 dB
8000 m - -109.2 dB
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