Environmental Conditions For Transponders/Tags; The Response Of Electromagnetic Waves In The Uhf Band; The Effect Of Reflections And Interference - Siemens Simatic RF600 System Manual

4.4

Environmental conditions for transponders/tags

Basic rules
The transponder/tag must not be placed directly on metal surfaces or on containers of liquid.
For physical reasons, a minimum distance must be maintained between the tag antenna and
conductive material. A minimum distance of 5 cm is recommended. The tag operates better
when the distance is greater (between 5 and 20 cm).
● Tag assembly on non-conductive material (plastic, wood) has a tendency to be less
critical than assembly even on poorly conductive material.
● The best results are achieved on the materials specified by the tag manufacturer.
● You can obtain more detailed information from the tag manufacturer.
4.5

The response of electromagnetic waves in the UHF band

4.5.1

The effect of reflections and interference

Reflections and interference
Electromagnetic waves in the UHF band behave and propagate in a similar manner to light
waves, that is they are reflected from large objects such as ceilings, floors, walls and
windows and interfere with each other. Due to the nature of electromagnetic waves,
interference can lead to wave amplification which can produce an increased reading range.
In the worst case, interference can also result in waves being extinguished which causes
holes in reader coverage.
Reflections can also be beneficial when they cause electromagnetic waves to be routed
around objects to a certain extent (deflection). This can increase the reading probability.
Due to these electromagnetic characteristics, it is extremely difficult in the multiple-reflection
environment that is usually found in the real environment on site, to determine propagation
paths and field strengths for a particular location.
Reducing the effect of reflections/interference on tag identification
● Reducing the transmit power:
To reduce interference to a minimum, we recommend that the transmitter power of the
reader is reduced until it is sufficient for an identification rate of 100%.
● Increasing the number of antennas to 3 or 4:
More antennas in a suitable antenna configuration can prevent gaps in reader coverage.
SIMATIC RF600
System Manual, xx/2014, J31069-D0171-U001-A15-7618
4.4 Environmental conditions for transponders/tags
RF600 system planning
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