What type of system could be used to recognize objects moving inside or outside of a motor vehicle?
Detecting an RFID tag as it moved through a car's doorway would be difficult. One issue is that if a person were to cover the tag with his or her hand, it would likely not be readable, since the RF energy would be absorbed by the body's water. Another issue is that passive RFID systems cannot determine a tag's precise location. A tagged object just outside a car's window could be read, for example, and the system might assume that the tag was within the vehicle.
My suggestion would be to employ a passive ultrahigh-frequency (UHF) system with a reader antenna in the roof of the car's interior. The interrogator could fill the interior with RF energy to power up the tag so that it could be read. The system would tell you if a tag were in or near the car. Testing would be required in order to determine the most effective locations for the reader antennas.
Perhaps one of our readers might have a better idea. If so, please post information here.
—Mark Roberti, Founder and Editor, RFID Journal
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