Characteristics - Siemens Simatic RF600 System Manual

RF600 system planning
4.3 Antenna configurations
* (L) is the reference to the linear polarization.
Dependencies
● Frequency dependency:
if a frequency dependency exists in the frequency band used, you must apply the highest
value in each case for the antenna gain. With the cable loss, on the other hand, you must
select the smallest value in each case it frequency dependency exists.
This procedure means that the permissible radiated power will not be exceeded in the
extreme case.
● Dependency on the plane
If the data for the antenna gain are different in the horizontal and vertical planes, you
must use the higher value in each case.
Impedance
Definition
Impedance is understood as the frequency-dependent resistance. The impedances of the
antenna, reader and antenna cables should always be the same. Differences in the
impedance result in mismatching which in turn means that part of the applied signal is
reflected again and that the antenna is not fed with the optimum power.
Specifications
● Only antennas can be used whose connection has a characteristic impedance of Z =
50 Ohm.
● The mechanical design of the coaxial antenna connection is of secondary importance; N,
TNC and SMA plug connectors are usual.
Return loss / VSWR
Definition
Since the impedance at the antenna connection is frequency-dependent, mismatching
automatically occurs with broadband use. This mismatching can be reflected by two
parameters:
● The voltage standing wave ratio VSWR
● The return loss
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System Manual, xx/2014, J31069-D0171-U001-A15-7618
SIMATIC RF600