Influence Of Metals; Influence Of Liquids And Non-Metallic Substances - Siemens SIMATIC RF600 System Manual

RF600 system planning
4.5 The response of electromagnetic waves in the UHF band
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.
4.5.2

Influence of metals

Metal can have an effect on the electromagnetic field depending on the arrangement or
environment. The effect ranges from a hardly determinable influence through to total blocking
of communication. The term metal in this context also includes metallized materials that are
either coated with metal or shot through with metal to such an extent that UHF radiation cannot
penetrate or only to a minimal extent.
The effect of metal on the electromagnetic field can be prevented as follows:
● Do not mount tags on metal.
● Do not place metallic or conducting objects in the propagation field of the antenna and
transponder.
Tags mounted directly onto metal
In general, tags must not be mounted directly onto metallic surfaces. Due to the nature of the
magnetic field, a minimum distance must be maintained between the tag antenna and
conductive materials. For further details on the special case of attaching transponders to
electrically conducting materials, see Section SIMATIC RF620T (Page 235) and
SectionSIMATIC RF640T (Page 271) .
In the case of transponders that are not designed for mounting on metallic materials, the
minimum permissible distance from metal is 5 cm. The larger the distance between the
transponder and the metallic surface, the better the function of the transponder.
4.5.3

Influence of liquids and non-metallic substances

Non-metallic substances can also affect the propagation of electromagnetic waves.
52 System Manual, 06/2010, J31069-D0171-U001-A10-7618
Draft Version 02.06.2010
SIMATIC RF600