SIMATIC RF642A
14
J31069-D0226-U001-A
2
-7618, 1
2
/2010
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 11), 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 and the associated representation of the reference system).
