ThingMagic M5e-Compact - Manual (Page 250)

ElectroStatic Discharge (ESD) Considerations
250 Appendix E: Environmental Considerations
Raising the ESD Threshold
For applications where full M5E power is needed for maximum tag read range and ESD is
suspected the following components are recommended additions to the installation to
raise the level of ESD the reader can tolerate:
Select or change to an antenna with all radiating elements grounded for DC. The MTI
MT-262031-T(L,R)H-A is such an antenna. The Laird IF900-SF00 and CAF95956
are not such antennas. The grounding of the antenna elements dissipates static
charge leakage, and provides a high pass characteristic that attenuates discharge
events. (This also makes the antenna compatible with the M5e antenna detect
methods.)
Install a Minicircuits SHP600+ high pass filter in the cable run at the M5E (or Vega or
other finished reader) end. This additional component will reduce transmit power by
0.4 dB which may affect read range in some critical applications. However the filter
will significantly attenuate discharges and improve the M5E ESD survival level.
Note
The SHP600+ is not rated for the full +30 dBm output of the M5E of Vega
reader at +85 degree C. Operation at reduced temperature has been
anecdotally observed to be OK, but has not been fully qualified by
ThingMagic.
Install a Diode Clamp* circuit immediately outboard from the SHP600 filter. This will
reduce transmit power by an additional 0.4 dB, but in combination with the SHP600
will further improve the M5E ESD survival level. * Not yet productized. Needs DC
power, contact [email protected] for details.
Further ESD Protection for Reduced RF Power Applications
In addition to the protective measures recommended above, for applications where
reduced M5E RF power is acceptable and ESD is suspected the following protective
measures can also be applied:
Install a one watt attenuator with a decibel value of +30 dBm minus the dBm value
needed for tag power up. Then run the reader at +30 dBm instead of reduced
transmit power. This will attenuate inbound ESD pulses by the installed decibel
value, while keeping the tag operation generally unchanged. Attenuators of 6 dB
have been shown to not adversely effect read sensitivity. Position the attenuator as
close to the M5E as feasible.
As described above add the SHP600 filter immediately adjacent to the attenuator, on
the antenna side.
Add Diode Clamp, if required, adjacent to the SHP600, on the antenna side.