User Manual

ThingMagic Nano User Guide 61
www.JADAKtech.com
Identifying ESD as the Cause of Damaged Readers
The following are some suggested methods to determine if ESD has caused reader failures, i.e., ESD
diagnostics. Some of these suggestions have the negative result experiment issue.
• Return failed units for analysis.
Analysis should determine if it is the power amplifier that has failed, but won’t be able to definitively
identify that the cause is ESD. However, ESD is one of the more common causes of PA failure.
• Measure ambient static levels with static meter, for example, AlphaLabs SVM2. High static doesn’t mean
discharges, but should be considered cause for further investigation. High levels that keep changing are
highly indicative of discharges.
• Touch some things around the antenna and operating area.
If you feel static discharges, that is an indication of what is in front of the antenna. What gets to the
ThingMagic Nano is also strongly influenced by the antenna installation, cabling, and grounding
discussed above.
• Use the mean operating time statistic before and after one or more of the changes listed below to
quantitatively determine if the change has resulted in an improvement. Be sure to restart your statistics
after the change.
Common Installation Best Practices
The following are common installation best practices to ensure the reader isn’t being unnecessarily
exposed to ESD, in even low risk environments. These should be applied to all installations, full power or
partial power, ESD or not:
• Ensure that ThingMagic Nano, reader housing, and antenna ground connection are all grounded to a
common low impedance ground.
• Verify R-TNC knurled threaded nuts are tight. Don’t use a thread locking compound that would
compromise the grounding connection of the thread to thread mate. If there is any indication that field
vibration might cause the R-TNC to loosen, apply RTV or other adhesive externally.
• Use antenna cables with double shield outer conductors, or full metallic shield semi rigid cables. JADAK
specified cables are double shielded and adequate for most applications. ESD discharge currents
flowing on the outer surface of a single shield coaxial cable have coupled to the inside of coaxial cables,
causing ESD failure. Avoid RG-58. RG-223 is preferred.
• Minimize ground loops in coaxial cable runs to antennas. Tying both the ThingMagic Nano and antenna
to ground (per item 1) leads to the possibility of ground currents flowing along antenna cables. The
tendency of these currents to flow is related to the area of the conceptual surface marked out by the
antenna cable and the nearest continuous ground surface. When this conceptual surface has minimum
area, these ground loop currents are minimized. Routing antenna cables against grounded metallic
chassis parts helps minimize ground loop currents.
• Keep the antenna radome in place. It provides significant ESD protection for the antenna’s metallic parts
and protects the antenna from performance changes due to environmental accumulation.
• Keep careful track of serial numbers, operating lifetimes, and numbers of units operating in order to
determine the mean operating lifetime. This number indicates if you have a failure problem, ESD or
otherwise. After any given change, it also indicates whether things have improved and if the failures are
confined to one instantiation or distributed across your population.