User's Manual

COBALT UHF-SERIES CHAPTER 9: RFID OVERVIEW
PAGE 127 OF 140
CHAPTER 9:
RFID OVERVIEW
9.1 RFID OVERVIEW
Cobalt UHF-Series products
are designed for use with
passive RFID tags, which do
not require batteries or
contain an internal power
supply. The tags collect the
power necessary to operate
from the RF field generated
by the reader and through a
process called backscattering
they can reflect some of this
power back to the reader,
thus creating a
communication channel.
When a passive tag comes in
contact with the RF field from
an RFID antenna, the
incoming radio frequency
signal generates a small, but
sufficient, electrical current
that powers the passive tag’s integrated circuit (IC)
When mounting RFID antennas and tags, it is important to understanding certain
principles. If your RFID application requires that the tag be attached directly to a
metal surface, always use a non-metallic tag spacer to avoid a possible reduction in
read/write range.
In addition, motors, conveyors and other automation equipment can produce
excessive electrical noise that may also negatively affect RF performance. Cobalt
UHF-Series products should only be used with well-grounded systems. Conveyor
equipment should be tied directly to an earth ground by an electrician. All cables
used on or around Cobalt UHF RFID devices must be shielded. Cable shields
typically should be grounded at only one end.
The majority of the Antenna-to-Tag range results specified in this publication were
measured in a free air environment – where no metallic objects were within the
antenna’s RF field. Yet because proximity to metals and other environmental
conditions can adversely affect read and write range, it is not possible to state
absolute range results achieved under all conditions. System integrators should
validate the RF performance of the RFID products used and should not rely solely on
Datalogic’s published range specifications.