Radio frequency identification is a broad term used to describe any method of identifying unique items via radio waves. Typically, a reader (also known as an interrogator) communicates with a transponder, which holds digital information in a microchip. The reader sends radio waves to the transponder, which responds with analogue signals that are converted into digital information.
RFID covers passive transponders that have no battery, as well as active tags that have a power source and can broadcast a signal. There are also chipless forms of RFID tags that utilize material to reflect back a portion of the radio waves beamed at them. Some of these systems use inks with chemicals that resonate at certain frequencies, or random metal fibers that reflect back a unique signal that can then be interpreted by a reader.
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—Mark Roberti, Founder and Editor, RFID Journal
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