RFID Journal Staff asked 8 years ago If we had a reader at the top of each corner of a hangar, and each one tracked an object's RFID chip, could we pinpoint that chip's location?
—Jordan
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Jordan,
There are many different types of RFID systems. Conventional passive low-frequency (LF), high-frequency (HF) and ultrahigh-frequency (UHF) solutions generally tell you that a tag is within the read field or has passed a reader antenna. These systems do not give you a reliable fix on the tag's distance from the antenna, however.
There are phased-array antenna systems that can provide three-dimensional location data. There are readers from Impinj, Mojix and View Technologies that can do this.
The tag's location is not extremely precise because radio waves bounce around and the signal from the tag might reach the reader antenna after bouncing off a metal shelf, rebar in the concrete floor or some other surface. This means you can't simply time how long it takes the tag's signal to reach the reader antenna and calculate the distance.
There is an active RFID technology called ultra-wideband (UWB) RFID that overcomes this multipath issue by having the tag broadcast at different frequencies. UWB systems are usually accurate to within 10 centimeters (3.9 inches). So if you were to put a tag on a container and placed reader antennas around your facility, you could locate that container very precisely. I hope this answers your question.
—Mark Roberti, Founder and Editor, RFID Journal
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