Planning wireless systems
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8.14 Equivalent isotropically radiated power (EIRP)
The equivalent isotropically radiated power (EIRP) is a gauge of the radiation power of an
antenna. The EIRP value is the sum of the transmission power in dBm and the antenna gain
in dBi.
Example at 2.4 GHz:
– Transmission power = 14 dBm
– Antenna gain = 8 dBi
– Cable attenuation (3 m EF 142) = 2.85 dB
– EIRP = 14 dBm + 8 dBi - 2.85 dB = 19.15 dBm
The EIRP depends on the frequency used. You may not exceed the following maximum
EIRP for legal reasons.
–For 2.4GHz:
– Maximum of 20 dBm outside Europe
– Maximum of 19 dBm in Europe, depending on the set transmission rate
– For 868 MHz:
–Maximum of 27dBm
• If the maximum EIRP is exceeded, adapt the cable, adapter or transmission power, if
necessary.
Panel antenna, 4 dBi
120 kbps 5 km
60 kbps 6 km
19.2 kbps 9 km
9.6 kbps 10 km
1.2 kbps 13 km
Yagi directional antenna, 8 dBi
120 kbps 7 km
60 kbps 8 km
19.2 kbps 12 km
9.6 kbps 15 km
1.2 kbps 18 km
Yagi directional antenna, 12 dBi
120 kbps 8 km
60 kbps 10 km
19.2 kbps 15 km
9.6 kbps 20 km
1.2 kbps 25 km
Table 8-10 Ranges for different antennas at 868 MHz
Antenna, 868 MHz [...] Data rate of the
wireless interface
Maximum range [...]