Radio Frequency (RF) Readers
RF readers comprise an antenna and electronic power circuitry to locate nearby tags and receive encoded information using radio frequency communication.
The reader emits high frequency radio waves that any nearby passive RF tag absorbs and stores long enough to power-up its own integrated circuit - which then uses the energy to beam back the ID number and any associated information to the reader.
The reader can also write basic information to the chip on the tag. For example, if the RF tag is inside a book, a code written to the chip may indicate the book has been checked out. A security gate reader will then receive this information from the tag to allow the book to pass through.
Many models of reader are hand-held devices (resembling a barcode scanner or pricing gun), but they can also be fixed in place (such as in security gates or counter-tops) or even hidden completely (embedded in ceilings or walls).