Siemens SIMATIC RF640A, Системное руководство

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5.2 SIMATIC RF615R
SIMATIC RF600
System Manual, 11/2018, J31069-D0171-U001-A21-7618
109
Overview of the antenna parameters
Table 5- 8 Maximum linear electrical aperture angle at 915 MHz:
Polarization (circular)
Azimuth section 100°
Elevation section 100°
Typical antenna gain
in the frequency band 902 to 928 MHz
0 dBi
Antenna axis ratio 2 dB
You will find more information on the antennas in the section "Guidelines for selecting RFID
UHF antennas (Page 51)".
5.2.2.2 Interpretation of directional radiation patterns
The following overview table will help you with the interpretation of directional radiation
patterns.
The table shows which dBi values correspond to which read/write ranges (in %): You can
read the radiated power depending on the reference angle from the directional radiation
patterns, and thus obtain information on the read/write range with this reference angle with
regard to a transponder.
The dBr values correspond to the difference between the maximum dBi value and a second
dBi value.
Table 5- 9 Range of antenna depending on antenna gain
Deviation from maximum antenna gain [dBr] Read/write range [%]
0 100
-3 70
-6 50
-9 35
-12 25
-15 18
-18 13
Example
As can be seen in the section Antenna diagram RF615R (ETSI) (Page 105), the maximum
antenna gain 0 dB is standardized. In the Azimuth diagram, the antenna gain falls by 3°dB at
approximately ± 39°. This means that the dBr value is -3. The antenna range is only 50 % of
the maximum range at ± 39° from the Z axis within the horizontal plane.