The Effects of Metal on RFID Tags: Detuning

Filed in archive Tags and Readers on November 3, 2005

Over at MoreRFID.com, our content partner (and an excellent site by the way), I found a link to a good white paper about RFID issues in metal environments.

The white paper, "How RFID Will Work in Metal Environments" (PDF), is by Trenstar. In one part it talks about a technical phenomenon known as "detuning":

Detuning
Metal can also detune both reader and tag antenna, causing added parasitic capacitance (which means energy drain caused by the electromagnetic "friction" from the metal) and reduced system performance. Finally, at some frequencies the energy reflected by metal creates interference between the tag and reader. RFID in heavy metal environments can mean reductions in actual read and write rates, ranges and reliabilities far below those experienced in the clean lab environments of RFID pilots. But what's also true is that proper system design and engineering will overcome most interference obstacles, and one use in particular has led companies to believe that this solution is worth looking into.

The physics of RFID make testing and re-testing imperative -- and can trip up information technology professionals.

I was speaking the other day with an executive of an RFID integrator who made this very point. He noted that IT departments, if they have not had previous experience dealing with RFID, may not grasp the full ramifications of pre-pilot equipment testing, pilots and field testing.

These tests serve a number of purposes, not the least of which is to see how well RFID tags and readers work in actual physical settings.

Certainly, IT Departments are used to the need to test software applications. But when you are dealing with software, it is not a question of how the software works in a particular physical environment. Physics does not enter into the equation all that much.

For IT professionals used to dealing with the virtual world of zeros and ones, it is a whole new ballgame to have to take into account the physical world. But that's precisely what they have to do with RFID.