Siemens SIMATIC RF650R Configuration Manual page 259

Changing the antenna position
In difficult radio conditions (e.g. where there is a lot of metal) it is possible that the
communication between transponders and readers is impaired. You can counter this by
changing the position of the antenna relative to the transponder. This also changes the
multipath propagation of the radio waves and obliteration is reduced or shifted.
Use of UHF algorithms
In the "Settings - Read points" menu item of the WBM, you will find various "Tools" in the
"Algorithms" area that you can use to improve the read/write reliability.
SIMATIC RF650R/RF680R/RF685R
Configuration Manual, 10/2015, C79000-G8976-C386-03
A.1 Planning and installation of UHF read points
Appendix
259