I plan to use passive RFID tags (operating at 865 to 867 MHz) for the purpose of vehicle identification. How would mobile phone radio signals affect the tags? How would electromagnetic interference (EMI) or electromagnetic compatibility (EMC) testing affect the tags? And how can chip memory data retention life be predicted?
—R. Suresh (Chennai, India)
Dear R. Suresh,
Your mobile phone should not interfere with a passive ultrahigh-frequency (UHF) tag's transmissions to a reader, or with a reader's transmissions to a tag. But best practices for any RFID deployment call for performing a site survey, which would involve having an RFID professional visit the locations where you intend to read tags with a spectrum analyzer, and determine any sources of EMI that could impact system performance or compatibility. This survey would tell you if cell phones, cordless phones or other devices would likely cause an issue for you.
As far as memory life is concerned, manufacturers include data retention information on their specification sheets for individual chips or tags. Impinj's Monza 5 chip, for example, offers 50 years of data retention. The data sheets for read-write chips would also tell you the number of read-write cycles.
—Mark Roberti, Founder and Editor, RFID Journal
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