A complete RFID system consists of a reader, an electronic tag or the so-called transponder and an application software system. The working principle is that the reader transmits a specific frequency of radio wave energy to the transponder to drive the transponder circuit and send out the internal data. At this time, the reader receives and decodes the data in sequence, then sends data to the application program for corresponding processing.
In terms of the communication and energy induction mode between the RFID card reader and the electronic tag, it can be roughly divided into inductive coupling and back scattering coupling. Generally, low frequency RFID mostly adopts the first mode, while the second mode is mostly used for higher frequency RFID.
An RFID reader can be a reading or reading/writing device according to the different structure and technology used. The RFID reader is the information control and processing center of RFID system. Readers are usually composed of coupling module, transceiver module, control module and interface unit. Half duplex communication is generally used for information exchange between the reader and the transponder. Meanwhile, RFID readers provide energy and timing sequence to passive transponders through coupling. In practical application, the management functions such as collection, processing and remote transmission of object recognition information can be further realized through Ethernet or WLAN. The transponder is the information carrier of the RFID system. At present, transponders are mostly passive units composed of coupling elements (coils, microstrip antenna, etc.) and microchips.