Minimum Distance To Antenna In Accordance With Etsi - Siemens SIMATIC RF600 System Manual

Safety Information
2.3 Safety distance to transmitter antenna
2.3.2

Minimum distance to antenna in accordance with ETSI

Minimum distance to antenna in accordance with ETSI (EU, EFTA, Turkey)
At a transmission frequency of 900 MHz, the wavelength of the electromagnetic wave λ is
approximately 0.34 m. For distances less than 1 λ in the near field, the electrical field
strength (1/r) diminishes exponentially to the power three over distance, and for distances
greater than 1 λ, it diminishes exponentially to the power two over distance.
The horizontal line at 41.25V/m marks the "safety limit value".
For the maximum permissible transmit power (1/r
"safety distance" d = 0.24 m. This means that personnel should not remain closer than 24cm
to the transmitter antenna for extended periods (more than several hours without
interruption). Remaining within the vicinity of the antenna for a brief period, even for repeated
periods (at a distance < 0.24 m), is harmless according to current knowledge.
Distance to transmitter antenna [m]
If the transmitter power is set lower than the highest permissible value (2 watts ERP), the
"safety distance" reduces correspondingly.
The values for this are as follows:
20
100
90
80
70
60
50
40
30
20
10
0
0,1 0,2 0,3
1
5
Radiated power ERP [W]
2.0
1.0
0.5
0,4 0,5 0,6
) in accordance with ETSI (2W ERP), the
2
Feld strength [V/m]
10
2
Safety distance to transmitter antenna [m]
System Manual, 05/2012, J31069-D0171-U001-A13-7618
0,7 0.8 0.9
% of limit value
24
5
0.24
0.17
0.12
SIMATIC RF600
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