Can a reader recognize students wearing tags inside a moving bus?
I assume that you mean the reader is affixed to a poll or some other structure outside the bus. If that's the case, then the answer is that it depends on what type of RFID system you are using. With a passive ultrahigh-frequency (UHF) solution, the radio waves from the reader antenna would bounce off the metal body of the bus. Some radio waves might penetrate the glass, power up the passive tags of a few students and be reflected back to the reader antenna, but you would have a very low read rate. I would be surprised if you could read much more than 10 percent of the tags.
You could employ active RFID tags, which use a battery to broadcast a signal. The energy would pass through the glass and you would achieve a much higher read rate. You would need to perform some testing to determine whether you could read 100 percent of the tags, which would probably be required for this type of application.
Another solution would be to place the reader at the bus entrance and interrogate the tags of students entering the vehicle.
—Mark Roberti, Founder and Editor, RFID Journal
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