Siemens SCALANCE W788-1PRO Operating Instructions Manual page 265

IEC 61196-4
Values for coupling losses according to IEC 61196-4 already include spatial
attenuation of 2 m. To calculate the actual coupling loss, a spatial attenuation for
the distance of 2 m must be deducted from this value. The coupling loss for a
specified distance between the RCoax cable and the antenna of the
communication partner is therefore calculated according to the following formula:
c = c - 20 * log(4π * 2m / λ) + 20 * log(4πd / λ)
d 95
c Coupling loss of the cable in dB for a specified distance between cable and
d
antenna.
c c
95 95
λ Wavelength of the electromagnetic oscillation in m; at a frequency of 2.4
GHz, the wavelength is 0.125 m.
d Distance between cable and antenna in m.
For a frequency of 2.4 GHz, you can also calculate with the following equation in
which you must specify the distance d in meters:
c
d 2.4 GHz
For a SIEMENS SIMATIC NET IWLAN RCoax Cable PE 1/2'' 2.4 GHz (c
dB at 2.4 GHz), for example, this results in the following coupling losses:
D istance
U U
1 m
2 m
5 m
10 m
100 m
Note
The formula is valid only for the 2.4 GHz RCoax cable.
Losses due to Power Splitters
Normally. when a double power splitter is used (one input, two outputs, for
example, RCoax N-Connect Female Power Splitter 2-Way) a loss of 3 dB must be
taken into account.
Operating Instructions SCALANCE W78x
C79000-G8976-C184-07
value of the coupling loss (specified in the data sheet of the cable)
= c - 46 dB + 20 * log(100 * d)
95
C oupling loss
U U
63 dB
69 dB
77 dB
83 dB
103 dB
Appendix
= 69
95
265