Siemens SIMATIC RF600 Series System Manual page 195

6.2.6.4 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.
Deviation from maximum antenna gain [dBr]
0
-3
-6
-9
-12
-15
-18
Example
As can be seen from the Antenna pattern ETSI (Page 189), the maximum antenna gain is -
5 dBi. In the vertical plane, the antenna gain has dropped to approx. -11 dBi at +40° and
320°. Therefore the dBr value is -6. The antenna range is only 50% of the maximum range at
± 40° from the Z axis within the vertical plane (see values shown in blue in the directional
radiation pattern: Characteristic of the vertical plane of the antenna and the associated
representation of the reference system).
SIMATIC RF600
System Manual, 10/2016, J31069-D0171-U001-A19-7618
Read/write range [%]
100
70
50
35
25
18
13
Antennas
6.2 RF620A antenna
195