Radio Frequency Identification

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RADIO FREQUENCY IDENTIFICATION Introduction RFID is a technology which enables detecting and identifying objects using electromagnetic radio waves. This is processed through exchange of information between a reader and a tag being attached to the object that includes the data associated with the object. This can be used to detect and classify vehicles, animals, patients, shipment goods and airline baggage. [1] RFID technology involves two main components, they are transponders which are also known as tags or labels, contain the relevant information about the object and other the interrogators, also known as readers or transceivers, that extract the data from the tags. These tags can be passive or active tags. Passive tags use the energy from the EM radiation of the reader for its processing, where as active tags receive power from an internal battery for its processing and communication with the reader. An integrated electronic circuit is embedded in tags for storage and processing operations and an antenna that transmits and receives the RF signal. [2] Figure : components of RFID Source : The tags used in RFID are enabled with read-write operations, with a large storage capacity. Data can be modified any number of times. Tag and reader act as two way radio communication in which each antenna carries the modulation and demodulation of RF signals, with operation frequency ranges from low frequency to UHF. As radio waves are used, RFID does not require line of sight for communication and the operating distance between the reader and tag varies according to the frequency range from few centimetres to few meters. [3] [1] [2] [3] History The start of RFID took place in 1915, by the British with a system called IFF, which means Identification Friend or Foe. In 1940, during Second World War, the first installation of IFF transponder was in a German aircraft named FUG. [4] Leon Theremin, in 1945 invented a device which retransmits an incident radio wave and audio information. This passive device which was activated from an external source became the forerunner for RFID technology. [5] The concept of RFID came into existence in 1973 when Mario Cardullo invented a passive transponder which emits information when activated by an interrogating signal and consisted a 16bit memory unit for storage purposes. [6] In 1973, at the Los Alamos National Laboratory, Steven Depp, Alfred Koelle, and Robert Freyman developed the RFID tag system that uses 12bit tags, operating at 915 MHz. [7] After many years of research RFID tags came out with active tags that eliminated the use of external power source.
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