Antennas
6.5 SIMATIC RF642A
SIMATIC RF600
306
System Manual, 06/2019, J31069-D0171-U001-A22-7618
6.5.6.3
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]
Read/write range [%]
0
100
-3
70
-6
50
-9
35
-12
25
-15
18
-18
13
Example
As can be seen in Directional radiation pattern in the ETSI frequency band (Page 303), the
maximum antenna gain in the horizontal plane is 6 dBi. In this plane and with the parallel
polarization axis at +70° or 300°, the antenna gain dropped to about 0 dBi. Therefore the dBr
value is 6. The antenna range is only 70° of the maximum range at + 50° or +300° from the Z
axis within the horizontal plane (see values shown in red in the directional radiation pattern:
Characteristic of the vertical plane of the antenna (Page 302) and the associated
