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RFID Reads Through Metal? Yes!


A funny thing happened on the way to the forum: innovation broke down yet another long-held myth. Myths are powerful. They become common knowledge. Everyone clings to them. They shape the way we thing about the world and the decisions we make. I’m not talking about Theseus, Paris, Helen and a thousand ships here. I’m talking about RFID reading through metal.

Pat King from Technologies ROI (TROI) knows a thing or two about busting myths. A materials chemist by training, he has become one of the most innovative RF engineers around through decades of experience and an unwavering faith in bulls-eye empiricism. That faith doesn’t rely on myth; it focuses on needs, oArmored RFID Tagpportunities, experimentation and results. It leads to innovation.

RFID Innovation Busts another Myth

The Armored Tag line is TROI’s latest innovation: a passive RFID tag with the tag encapsulated under a metal dome. Aside from the trick that reader antennas facing the metal surface can capture the tag ID behind the metal, it has the practical benefit of being rugged. And, it is specifically designed to be mounted on other metal surfaces. The Armored Tag’s (I’m told the first of several variations) rugged exterior and metal surface makes it almost seem camouflaged when applied to metal assets.

Putting the Armored Tag to the Test

We didn’t have a formal benchmark scheduled, but ODIN labs still wanted test the tag to verify the claims. The short summary of the testing: it works. The read range isn’t as long as other TROI tags due to the attenuation and shadowing caused by all of that metal, but it is more than sufficient to work with a variety of common use cases. We have a good idea why it works based on our engineering experience with RFID pipe tagging. However, we’ll let you ask Pat for his official answer.

Metal Still Poses Challenges for RFID

Does this mean metal no longer impedes RFID performance? Not at all. Metal still has properties that reflect RF waves and can effectively prohibit tag reads in certain use cases (laptops in stored at the bottom of metal file cabinets comes to mind). However, it shows that some ingenuity and good engineering can produce useful new products and bust a myth in the process.

I recall the RFID World conference in Dallas in 2006 when Impinj demonstrated that passive RFID tags could be read while floating in bottle of water. In fact, many tags will work in the same scenario but Impinj was the first to see the marketing value of the demonstration. Despite the evidence, people still tell me that RFID can’t read around water. Others tell me that passive RFID can’t read on metal. It is true that read performance is typically less in both cases than in more benign RF settings, but both statements are false, persistent myths. I am sure I will be told several times this year that passive RFID can’t read tags through metal. I will be happy to set the record straight and use the new TROI Armored Tag as my evidence.


Well done Brett. Would be interested to learn more of your testing and the applications that this new tag may open
Posted @ Sunday, June 27, 2010 5:28 PM by Ken Laing
We will be showing some testing of this tag and others in the future on this blog and through publications of the RFID Benchmark Series. Post a comment if there are any tests you would like to see performed and we may be able to get them included. Thanks for the comment Ken.
Posted @ Wednesday, August 04, 2010 9:41 PM by Bret Kinsella
Very nice this blog, 
im looking for information about cases of study in medicinal cylinders or LGP cylinder.  
If someone knows about this please contact me. Thanks.
Posted @ Monday, August 23, 2010 10:54 AM by Alejandro
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