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Does Direct Sunlight Affect Tag Readability?

Posted By RFID Journal, 05.07.2018

My company utilizes RFID tags to mark commodities for the purpose of tracking their every move. When they are unloaded or loaded from a container, they are scanned so we can know where they are. An issue has cropped up a couple of times, and I'm trying to understand how it may be occurring.

An individual takes various commodities and places them on a belt to be dispersed where they need to go. The belt uses a laser line to determine when an item has crossed a threshold, communicating to the RFID reader to interrogate the tags. If items are too close, we see the safety mechanism kick in and stop the belt, because not more than one will be scanned at a time. We don't want un-scanned items moving by.

However, when direct sunlight is involved, the whole system seems to be troubled. I thought maybe the Sun was shining into the lasers and causing a problem, but when we created shadows over the laser eyes providing the laser line, the issue remained. It only seems to occur in direct sunlight. Could the Sun somehow interfere with RFID scanning? I'm at a loss for what is taking place.




Direct sunlight should have no impact on a reader's ability to interrogate an RFID tag. The only thing I can think of as a potential problem would be if the sunlight were causing the readers to overheat and stop working. You could check this by determining whether the reader antennas are emitting energy; you could use an ePix PowerMapper, or another device that measures RF energy, to ascertain whether signals are being emitted from readers when this problem occurs.

—Mark Roberti, Founder and Editor, RFID Journal


Jos Kunnen 2018-05-10 04:05:55 AM
Hunter, We were intrigued by your reported problem. One potential failure mechanism we thought of was the potential of strong sunlight affecting unencapsulated tag chips, similar to that reported with the Raspberry Pi. https://www.raspberrypi.org/blog/xenon-death-flash-a-free-physics-lesson/s We tested a variety of unencapsulated tags, subjecting them to strong light, but were not able to reproduce any such failures. The operating temperature range of readers typically is up to around 80 C, so we are unsure if this would be the cause. As Mark suggests, try to diagnose with an RF meter. Alternatively, try shielding the various system components from the direct sunlight and see if you can isolate the cause. Jos Kunnen, CEO Times-7 Research Limited

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