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Antenna patterns
5.4 Interpretation of directional radiation patterns
5.4
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 you can see in the pattern in the section "Antenna patterns in the ETSI frequency band
(Page 18)", the maximum antenna gain is -5 dBi. In the vertical plane, the antenna gain has
dropped to approx. -10 dBi at +40° and 320°. This means that the dBr value is -5. The antenna
range is only 50% of the maximum range at ± 40° from the Z axis within the vertical plane
(see line shown in blue in the directional radiation pattern: Characteristic of the vertical plane
of the antenna and the associated representation of the reference system).
24
Read/write range [%]
100
70
50
35
25
18
13
Operating Instructions, 11/2020, C79000-G8976-C601-01
SIMATIC RF622A
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