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RFID tag

The radio frequency identification (RFID) tag is a small integrated-circuit chip with a radio circuit and an identification code embedded into it that can be scanned from a distance.

The tags can be used for the identification of persons and goods. The tiny tags are likely to replace the current barcodes at such places as retail chains.

RFID tag
RFID tag

The RFID tag consists of microchip and an antenna. There exists three kind of tags:

  • Passive tags
  • Semi-passive tags
  • Active tags

Passive tags get their energy from the field of the reader through induction. Passive tags are the simplest, smallest and cheapest version of an RFID tag as they do not contain a built-in power source and consequently cannot initiate communication with a reader. As the available power from the reader field diminishes rapidly with distance, passive tags have practical read ranges that vary from about 10 mm up to about 5 metres.

Semi-passive tags have built-in batteries to power the chip on the tag. They use power from the RFID reader to respond. Due to the use of batteries, semi-passive tags are faster and stronger to respond back on receiving a signal compared to passive tags. This allows them to act over greater distances.

Active tags are battery powered devices that have an active transmitter onboard. They can communicate over longer distances (several kilometres) and have read/write capabilities allowing tag data to be rewritten or modified over the lifecycle.


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