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radio frequency identification (RFID)

Radio FrequencyIdentification (RFID) is a wireless method for marking and identifying goods, objects, people and livestock. It is an electronic process that works without contact and transmits the goods data over a certain distance with radio, inductive or resonance coupling. An RFID system consists of the data carrier, i.e. the RFID tags, an antenna and the RFID reader.

RFID tags - which are transponders with a microprocessor and memory - are used to identify goods, pallets, containers or people and use the Electronic Product Code (EPC). The bridgeable distance between the tag and the RFID reader depends on the type of RFID tag, the shape and size of the antenna, the RFID frequency and the RFID transmission and can range from a few millimeters to several tens of meters. To prevent eavesdropping on the radio transmission, the distances between the RFID tag and the reader are specified and, according to ISO 14443 and ISO 15693, are about 15 cm for inductive coupling in the long-wave frequency range, about 1.5 m for high frequency and backscatter, and about 15 m in the UHF range.

Active, passive and semi-passive RFID tags

In general, a distinction is made between active, passive and semi-passive tags. Active tags have a rechargeable battery and a transmitter and send the data to the RFID reader.

Different distance based RFID systems

Different distance based RFID systems

The range of active tags is much longer than that of passive tags. Passive RFID tags do not have their own power supply, they receive their power from the reader via radio. Depending on the system and the application, frequencies in the long-wave and short-wave range, but also in the UHF range and in the microwave range are used as RFID frequencies. As a rule, the frequency bands are ISM bands.

Structure of an RFID card as a contactless chip card with antenna coil and chip

Structure of an RFID card as a contactless chip card with antenna coil and chip

When an RFID tag is activated, the reader sends its carrier and data signal to the RFID transponder. This influences the electromagnetic field of the carrier signal by rapidly switching on and off attenuations, which is expressed in a temporary attenuation of the carrier signal. This temporary attenuation of the carrier signal, which is a load modulation and is detected by the reader, contains the information from the RFID card to the RFID reader. The readout time is in the millisecond range and the bridgeable distance depends on the transmission technology and the antenna. With radio transmission, which works with frequencies from 128 kHz, distances of up to one meter can be bridged with stationary readers. The RFID transmission between tag and reader works with an anti-collision algorithm and has a data transfer rate of 9 kbit/s.

Application areas of RFID

RFID tag with flat coil, photo: Tagnew

RFID tag with flat coil, photo: Tagnew

Tags are used in merchandise management systems and logistics, as well as in the personal area for access control and electronic ticketing, in animal identification or in motor vehicles as immobilizers, in the recording of tolls and the creation of traffic profiles, and also on smart cards.

RFID supports manufacturers, suppliers, freight forwarders and distributors in logistics, optimization of warehousing and invoicing. In personal use and on smart cards, RFID technology can be used to create movement patterns and analyze purchasing behavior.

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Englisch: radio frequency identification - RFID
Updated at: 26.11.2018
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