Radio frequency identification (RFID) technology uses radio signals to identify, locate and track a variety of objects, such as merchandise, animals, people and vehicles. An RFID system consists of an RFID tag or transponder, which carries information about an object; an RFID reader or scanner, which reads the tag, and a database, which stores further information about the tagged object.
RFID Tag
An RFID tag or chip consists of a tiny silicon microchip; an integrated circuit, which modulates and demodulates the radio signals, and an antenna, which receives and transmits the radio signals. An RFID tag contains a unique identity code, has a small amount of storage capacity and can typically perform a limited amount of processing in its own right. An RFID tag can be thought of as an electronic bar code, but no direct line of sight is needed between an RFID tag and an RFID reader because the technology uses radio signals rather than visible light. The RFID reader transmits a low-level radio signal and it is to this signal that the RFID tag responds.
Active Tags
Active RFID tags contain an internal power source in the form of a battery, which allows them to be read at a longer range than their passive counterparts and to store information sent by the RFID reader. The presence of a battery means that active RFID tags are larger than passive RFID tags and are dependent on the life of the battery. However, batteries typically last about 10 years and provide better accuracy, reliability and performance, particularly under adverse conditions. Active RFID tags can typically be read from many feet away.
Passive Tags
Passive RFID tags, on the other hand, have no internal power source. Incoming signals from an RFID reader create electrical current in the antenna of a passive RFID tag and energize, or activate, the tag just long enough to transmit simple information, such as an electronic product code. Passive RFID tags are small and inexpensive when compared with active RFID tags, but their range is usually limited to less than 20 feet.
Frequency
RFID tags are categorized by the range of radio frequencies in which they operate. Microwave tags operate at the highest frequency, around 2.45 gigahertz; followed by ultra-high frequency tags between 868 and 956 megahertz; high frequency tags at around 13.56MHz and low frequency tags between 125 and 134.2 kilohertz.
Tags: RFID tags, RFID reader, radio signals, frequency tags, active RFID