RFID is a technology that uses radio waves to automatically locate and identify individual products, place and transact data quickly. An RFID system comprises of an electronic portable device called transponders or tags, an antenna, a controller and a reader. These systems communicate via radio signals that carry data either unidirectionally or bidirectionally.
An RFID tag is made of three components, an antenna, a substrate and an integrated circuit. The circuit comprises of coded information that draws power from a magnetic field to transmit information back to the reader. The tag can be of two types, active (emitting radiation) or passive (not emitting radiation), which means that tags can broadcast information or just transmit when queried by a reader. The tag can be either read-only or read-write. Passive RFID tags have a limited range of around 50 cm, while active tags can transmit up to 85 cm, which can be detected by high-frequency readers. Tags can store a vast range of data, including product serial number, manufacturing and expiry dates.
The purpose of the antenna is to transmit radio waves to and from the mobile tracking device. The controller manages this communication and moves the data between the antenna and the personal computer or PLC (Programmable Logic Controller) device. A PLC device is an RFID reader and writer machine that has both an internal antenna and a controller.
The reader emits radiation to a tag, which helps in detecting products if it is within the reach, usually within 100 meters. The reader automatically captures data transmitted from the tag if it is within the prescribed range. RFID readers can be of low frequency, high frequency or UHF (Ultra High Frequency), and can support a very broad range of protocols. There is also a choice of low-power readers, and high-power readers for intensive operations. Readers can be easily set up anywhere because the tags do not need to be in line-of-sight of transmit.
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