RADIO FREQUENCY IDENTIFICATION IntroductionRFID is a technology that allows objects to be detected and identified using electromagnetic radio waves. This is processed through the exchange of information between a reader and a tag attached to the object that includes the data associated with the object. It can be used to detect and classify vehicles, animals, patients, shipping cargo and airline baggage. [1]RFID technology involves two main components, transponders, also known as tags or labels, which contain the relevant information about the object and other interrogators, also known as readers or transceivers, which extract data from the tags. These tags can be passive or active tags. Passive tags use the reader's EM radiation energy for its processing, while active tags receive energy from an internal battery for its processing and communication with the reader. The tags incorporate an integrated electronic circuit for storage and processing operations and an antenna that transmits and receives the RF signal. [2]Figure: Components of RFIDSource: http://www.docstoc.com/docs/17328767/Draft-SP800-98Tags used in RFID are enabled with read-write operations, with large storage capacity. The data can be modified any number of times. Tag and reader act as two-way radio communication where each antenna carries modulation and demodulation of RF signals, with operating frequency ranges from low frequency to UHF. Because radio waves are used, RFID does not require line of sight for communication, and the operating distance between the reader and the tag varies depending on the frequency range from a few centimeters to a few meters. [3] [1] http://en.wikipedia.org/wiki/Radio-frequency_identification[2] [3] http://www.docstoc.com/docs/17328767/Draft-SP800-98HistoryThe beginning of RFID took place in 1915, by the British with a system called IFF, which means Identification Friend or Foe. In 1940, during World War II, the first installation of the IFF transponder occurred on a German aircraft called FUG. [4]Leon Theremin, in 1945, invented a device that retransmits an incident radio wave and audio information. This passive device activated by an external source became the precursor of RFID technology. [5]The concept of RFID originated in 1973 when Mario Cardullo invented a passive transponder that emitted information when activated by an interrogative signal and consisted of a 16-bit memory unit for archival purposes. [6]In 1973, at Los Alamos National Laboratory, Steven Depp, Alfred Koelle and Robert Freyman developed the RFID tag system using 12-bit tags, operating at 915 MHz. [7]After many years of research, the tags RFID came out with active tags that eliminated the use of an external power source.