User Manual

28
Mini-RFM - Reference Guide November ’00
d.
Noise
, i.e. magnetic interference energy in or close to the TIRIS frequency range
can reduce the read range remarkably. Sources of interference can be, for
example: electronic equipment with built-in switch mode power supplies, monitors
and TV-sets with their magnetic deflection, which are not shielded enough. In such
conditions you may be able to obtain better read/write ranges with a smaller
antenna rather than a large one. The reason for this is that a large antenna collects
signals within a larger area and therefore produces a stronger interference signal
compared with the relatively small transponder signal. Under some conditions,
charging and/or writing to the transponder works excellently, but the reading unit
cannot detect the transponder signal.
Figure 15 shows the dimensions of the ferrite stick antenna RI-ANT-P02A available
for the RF Module RI-RFM-003B.
Figure 15: Stick Antenna RI-ANT-P02A