Where Can I Find an RFID Device That Would Detect When a Tag Crossed a Line?


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Ask The ExpertsCategory: QuestionsWhere Can I Find an RFID Device That Would Detect When a Tag Crossed a Line?
Kealan Mannix asked 2 years ago

The device must be accurate (that is, it can't just read tags a few meters in front of or behind the line), as it will be used for timing purposes. It must read passive tags and it would be used underwater. Do you know of any device that would be capable of reading tags as they passed the line consistently and accurately? I was thinking of using a reader that would be placed along the length of the line (50 to 100 meters) and could read tags that passed 4 or 5 meters over the top. If you know of a method of doing this, or a device that is available for that purpose, it would be great.


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If you are looking for an RFID system that would allow tags to be read underwater, low-frequency (LF) or high-frequency (HF) RFID are your only options. Ultrahigh-frequency (UHF) RFID tags cannot be read underwater since the liquid would absorb the RF energy at that frequency. However, LF and HF tags can be read from a distance of only about 3 feet (1 meter), so you would be unable to read tags that were located 4 or 5 meters above the reader antenna. You would need to find a way to keep the tags within about a meter of the antenna. I suggest you contact  RFID Inc. to find out if they can assist you. You might also try  Oregon RFID, which has had success in tracking fish by running a loop antenna across streams 200 feet wide. Good luck!

Mark Roberti
Founder and Editor
RFID Journal


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