Can an RFID Tag Be Masked By a Radio Signal?

How can I prevent a UHF tag from being read?

—Name withheld

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There are radio waves all around us all the time. Cell phones, Wi-Fi routers, cordless phones and many other devices use radio waves, but if you are concerned that these or other devices can pick up data on a passive ultrahigh-frequency (UHF) tag, you need not worry. First, for a tag to be interrogated, the reader must be operating at the same frequency. A 2.4 GHz Wi-Fi router cannot communicate with a 915 MHz passive UHF tag, any more than an FM radio can pick up AM stations. Antennas are tuned to receive signals only in a certain frequency band.

Another issue is that passive UHF tags use a very specific air-interface protocol, which is the language by which tags and readers communicate. Other RF devices use completely different air-interface protocols. Trying to read a passive UHF tag with a Wi-Fi router is like trying to understand a German AM radio station when you have an FM radio and speak Japanese.

It is possible for any passive UHF reader based on the EPC Gen 2 air-interface protocol standard to read any tag based on the same standard. That's important, so that supply chain partners can read information on the same tag. If you are concerned about others reading data on a tag, then you might look at the EPC Gen2V2 protocol, which enables tags to authenticate a reader for additional security (see GS1 Ratifies EPC Gen2v2, Adds Security Features, More Memory). There aren't a lot of tags available that use the new features, but there will be a growing number of them over time.

You could also put data in a secure database and associate it with a specific tag ID. That way, anyone interrogating a tag would only read a serial number, and would not have access to secure data.

—Mark Roberti, Founder and Editor, RFID Journal