Would the technology be appropriate for such an application?
Generally speaking, RFID technology is used to identify things that are tagged or have ID cards with embedded transponders. So an access-control system, for instance, can keep people out by requiring them to present an RFID-enabled employee badge to a door reader. Without the proper badge, the door would remain locked.
RFID is not generally used to detect intruders, since they typically do not tag themselves so they can be tracked and identified. However, I am aware of one novel use of passive ultrahigh-frequency (UHF) tags that takes advantage of the human body's ability to absorb radio waves at the frequencies used by passive UHF systems, in order to detect the unauthorized presence of a person.
Here's how it works: Tags are placed along a perimeter wall, every few feet, with readers installed every 10 feet or so from each other and set back from the wall by about 15 to 20 feet. The tags are read constantly, so if someone climbs over the wall, his or her body comes between a tag and a reader, temporarily blocking the signal from reaching the reader, and thus indicating an intruder's presence.
We feature a white paper in our library explaining the design of such a system, titled "Intrusion Detection with Radio Frequency Identification: Secure, Consistent and Easily Deployed Intrusion Detection." I am unaware of any business or organization that has deployed this patented solution so far, though it is possible that companies have done so and simply want to keep quiet about it. The patent holder and author is Kenneth B. Cecil, whose contact information is listed in the white paper.
—Mark Roberti, Founder and Editor, RFID Journal
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