Siemens SIMATIC RF200 System Manual page 23

Secondary fields without shielding
The following graphic shows typical primary and secondary fields, if no shielding measures
are taken.
Figure 4-6
In this arrangement, the reader can also read transponders via the secondary field. Shielding
is required in order to prevent unwanted reading via the secondary field, as shown and
described in the following.
SIMATIC RF200 IO-Link
System Manual, 03/2012, C79000-G8976-C276-01
Secondary field without shielding
Planning an RF200 IO-Link system
4.1 Fundamentals of application planning
23