Siemens SIMATIC RF600 System Manual page 62

RF600 system planning
4.3 Antenna configurations
Use with other units
As with other units, there are also different versions of the unit for decibel depending on the
reference variable. With this reference, the logarithmic power ratio becomes an absolute
variable. The following table lists the most important combinations in this context with other
units:
Versions of decibel
0 dBm
dBi
dBd
dBic
Antenna gain
Definition
The antenna gain specifies the degree to which the antenna outputs or receives its power in
the preferred angle segment.
With this theoretical variable, a comparison is always made with an isotropic spherical
radiator, a loss-free antenna which does not exist in reality. It describes how much power
has to be added to the isotropic spherical radiator so that it outputs the same radiated power
in the preferred direction like the antenna to be considered. The unit for the antenna gain is
therefore specified in dBi (dB isotropic).
The antenna gain is defined for the receive case as the ratio between the power received in
the main beam direction and the received power of the isotropic spherical radiator.
Specifications
You must know the antenna gain in the corresponding frequency band or range. You can
obtain the value of the antenna gain from the technical specifications of your antenna
vendor.
● With a cable loss of 4 dB, a gain ≥ 6 dBi(L) is required since otherwise the maximum
● In the case of antennas used in the FCC area of approval, a gain of at least 6 dBi(L) is
● If the gain is > 6 dBi(L)*, the difference is compensated in accordance with the directives
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radiated power will not be achieved.
required since otherwise the permissible radiated power of 4 W EIRP will not be reached.
by reducing the transmitted power.
Description
Power level with the reference variable 1 mW.
Power level with the reference variable on the isotropic spherical
radiator (see also Section Antenna gain (Page 60) ).
The relationship between dBi and dBic is as follows:
dBi = dBic - 3
Power level with the reference variable on the dipole radiator.
The relationship between dBd and dBi is as follows:
dBd = dBi - 2.15
Power level with the reference variable on the isotropic radiator for
circular antennas.
The relationship between dBi and dBic is as follows:
dBic = dBi + 3
System Manual, 05/2012, J31069-D0171-U001-A13-7618
SIMATIC RF600