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What is RFID?



The abbreviation RFID stands for Radio Frequency Identification . It refers to a technology that uses radio waves for the remote exchange of data between an RFID reader and a so-called RFID tag, which is attached to a specific (mobile) object.

The signals from an RFID chip (mounted on the RFID tag) are received by the RFID reader by means of an antenna. The RFID reader translates the radio signal into digital form, for example a tag identification number. The RFID tag is also equipped with an antenna which can be used to add new data to the RFID Chip or to modify or remove existing data .

RFID is not a new technology. A well-known application is the recording of timing during sport competitions. A chip is attached to the runners' shoes in order to measure start and finish times in track and field sports. The time is recorded as the competitors run across a special mat.


  Passive versus active technology?

RFID tags are available in a wide range of formats and dimensions. The figure on the left shows a tag at actual size. Whether a tag is passive, semi-passive or active is significant for its dimensions. The main difference between these types of tag is that the active and semi-passive tags contain batteries. An active tab continuously transmits its unique identification number at set intervals (for example every 5 seconds). A passive tag only becomes active and sends out its unique identification number when it is in the vicinity of an antenna. Like passive tags, semi-passive tags only transmit their unique ID when they are in the vicinity of an antenna. The battery is used to support the chip's memory capacity and intelligence, and can also amplify the transmitted signal, allowing the reading distance to be increased.
Active tags are generally more expensive, and the service life of the tag is determined by the tag. Passive tags are generally smaller and cheaper and last many times longer than the active and semi-passive varieties.

For a categorization of tags by EPC Global see Standardisation→ Tags