Foreign RFID (Radio Frequency Identification): Principles and Applications RFID is a complete system that is composed of important components: the RFID tags, the RFID readers or transceivers, and the database. The tags carry object-identifying data. RFID readers or transceivers can read and write tag data, while the database stores records that is used for tag identification. (Weis, S., 2007)
RFID tags can be divided into three classes based on their power source: active, semi-passive and passive. Active tags have their own source of power source, such as a battery, and can initiate communication to a reader or other active tags. Semi-passive tags also have their own internal battery, but they are unable of initiating communication. This ensures that it is only active when readers query it. Passive tags have neither a power source nor a capability of initiating communication but are the cheapest among the three. (Weis, S., 2007)
RFID systems can operate at a variety of radio frequencies. Each of these frequencies has its own operating range, power requirements and performance. Low Frequency, or LF, operates at 120-149 KHz and have a read distance of 10-20 cm. High Frequency, or HF, operates at 12.56 MHz and have a read distance of 10-20 cm. Ultra-High Frequency (UHF) operates at 868-928 MHz and has a range of 3 meters. Microwave operates at 2.45 and 5.78 GHz and can read up to 3 meters. Ultra-Wide Band (UWB) operates at 3.1-10.6 GHz and has a read distance of 10 meters.