I plan to build an RFID-based bus-monitoring system. Can you please tell me the reception range of an RFID interrogator and its price? How about the tags?
The range would depend on the type of RFID technology you plan to use. Passive high-frequency (HF) ID cards would have a range of about 18 to 24 inches. Passive ultrahigh-frequency (UHF) transponders would have a read range of probably 10 to 15 feet, though the UHF signal could be blocked by people (UHF radio waves are absorbed by water, of which the human body is mostly composed). Battery-assisted UHF transponders could be read from 30 feet away or so, and would work better around the human body, while active systems could be interrogated from a distance of 1,000 feet.
I would not recommend using an active RFID system, since you would likely be reading tags on children outside of a bus. Passive HF readers can be purchased for $300 to $400 apiece, but would require that each student present his or her ID card. Passive UHF readers cost $800 to $2,000 each, depending on the model and features chosen. They would be able to read tags in student IDs without each child having to present the card to the reader.
As for the tags, they would probably cost you about a dollar each, when encased in plastic and printed with a photo and the student’s name. Battery-assisted tags would cost more, since they would have a battery and a plastic housing. I’d say you would likely pay $5 to $10 each.
—Mark Roberti, Founder and Editor, RFID Journal
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