Losses Based On The Example Of A 2.4 Ghz Rcoax Cable - Siemens SCALANCE W788-1PRO Operating Instructions Manual

Losses Based on the Example of a 2.4 GHz RCoax Cable

Losses due to Longitudinal Attenuation
The longitudinal attenuation of the leaky feeder cable depends on its length and is
calculated according to the following formula:
a = α * l
rc rc
a Longitudinal attenuation of the cable in dB
rc
α Attenuation coefficient in dB/m as specified in the technical specifications of
rc
the cable:
RCoax Cable 0.17 dB/m at 2.4 GHz
connecting cable: 0.55 dB/m at 2.4 GHz
l Total length of the cable in m
The values for the RCoax cable can be found in the technical specifications in
Chapter 7.
Losses due to Coupling Loss
Coupling loss c
surrounding space. The coupling loss depends on the construction of the cable and
its physical properties. Values for coupling loss are therefore specified for the
particular cable in the technical specifications.
Losses Due to Spatial Attenuation
Spatial attenuation a
communications partner. The decisive factor here is therefore the distance
between the RCoax cable and communication partner. The following formula is
used:
a = 20 * log(4πd / λ)
fr
a Spatial attenuation in dB.
fr
d Distance between cable and antenna in m.
λ Wavelength of the electromagnetic oscillation in m; at a frequency of 2.4
GHz, the wavelength is 0.125 m.
Note
The formula is valid only for the 2.4 GHz RCoax cable.
Operating Instructions SCALANCE W78x
C79000-G8976-C184-07
includes the losses at the transition from the cable to the
d
specifies the attenuation between the RCoax cable and the
fr
Appendix
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