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| Background RFID or Radio Frequency Identification was originally developed during the second world war by the UK air force to tell friendly planes from enemy planes. All friendly planes had an RFID tag in the tail, that beaconed a code that was recognized by the other planes. At its base, RFID is a very simple radio that basically emits or receives an identification code. High usage started in the mid 1980's when farmers starting inserting RFID tags in the ear of their cows, so they could be automatically individually identified. The largest application is still access control. There are two basic types of tags: passive tags that
do not have a battery and active tags that do. A passive RFID tag
is basically just an integrated circuit and an antenna. There are several
types of active tags with or without sensors. Active tags send a beaconing
signal at a predefined moment for example every minute which are picked
up by a reader. There are also semi active or battery assisted tags, that
work like passive but use the battery to strengthen the return signal. |
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