IFM Electronic ANT805, Руководство по эксплуатации

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UK
RFID UHF antennas
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4 Reading range and selectivity
The reading range and the selectivity are the most important features of an RFID
application� The reading range describes the greatest distance at which a tag
can be read� The selectivity indicates the required minimum distance for clear
distinction between two adjacent tags�
The system features depend considerably on the tag type used� In general, the
UHF RFID tags can be divided into three groups�
Figure: Loop-shaped tag
The first group consists of loop-shaped tags that
couple magnetically with the antenna� These tags
have the smallest ranges since the magnetic field
decreases rapidly with the distance from the antenna�
The second group consists of hybrid-type tags which
are a mix of loop-shaped and dipole-type tags� These
tags can be activated by the antenna via the
magnetic field, the electric field or a combination of
both�
The third group is made up of dipole-type tags (far
field tags) which mostly couple via the electric field�
Ranges of more than 10 m are possible�
4.1 Antenna allocation according to tag types
The ANT805 ultra-low-range antenna was developed to meet the most challenging
demands with regard to range and selectivity of the tags from all three groups� It is
a universal antenna for many low-range applications� With this antenna very low
reading ranges below 10 cm and high selectivity with far-field tags are possible� It
can also read near-field tags at distances of up to 3 cm�
In order to significantly increase the read distance for near-field tags, the ANT810/
ANT910 low-range antenna was developed for reading ranges of 7 cm with
conventional loop-shaped tags�
The ANT805 ultra-low-range antenna is suited for all groups while the ANT810/
ANT910 low-range antenna is particularly suited for use with loop-shaped tags�
4.2 Reading range
In order to quantify the reading range of the ANT805 and ANT810/ANT910
antennas the figures below show the respective reading ranges for different tag
designs� The tags are aligned parallel to the antenna�
The ANT805 antenna has a very well-defined reading range for all tags� The
ANT810/ANT910 antennas are special solutions for near-field tags with a
considerably larger reading range than the ANT805 antennna�
Figure: Hybrid-type tag
Figure: Dipole-type tag