The basic working principle of RFID technology is not complicated: after the tag enters the magnetic field, it receives the RF signal sent by the interpreter, and sends the product information stored in the chip (Passive Tag, passive tag or passive tag) with the energy obtained by the induced current, or actively sends the signal of a certain frequency (Active Tag, active tag or active tag); After the information is read and decoded by the interpreter, it is sent to the central information system for relevant data processing.

A complete RFID system consists of a reader, an electronic tag (TAG), the so-called transponder and an application software system. Its working principle is that the reader transmits radio wave energy of a specific frequency to the transponder to drive the transponder circuit to send the internal data. At this time, the reader receives the interpreted data in order and sends it to the application program for corresponding processing.

From the perspective of communication and energy sensing between RFID card readers and electronic tags, it can be roughly divided into two types: inductive coupling and backscatter coupling. Generally, the first type is used for low frequency RFID, while the second type is used for high frequency RFID.

The reader can be a read or read/write device according to the structure and technology used, and it is the information control and processing center of the RFID system. Reader is usually composed of coupling module, transceiver module, control module and interface unit. Half duplex communication mode is generally adopted for information exchange between the reader and the balise, and the reader provides energy and timing for the passive balise through coupling. In practical application, it can further realize the collection, processing, remote transmission and other management functions of object identification information through Ethernet or WLAN. Balise is the information carrier of RFID system. At present, most balises are passive units composed of coupling elements (coils, microstrip antennas, etc.) and microchips.

In the practical application of RFID system, the electronic tag is attached to the surface of the object to be identified, and the electronic data in the agreed format is stored in the electronic tag. The reader can read and identify the electronic data stored in the electronic tag without contact, so as to achieve the purpose of automatic identification of objects. The reader sends a RF signal of a certain frequency through the antenna. When the tag enters the magnetic field, it generates induced current to obtain energy, and sends out its own coding and other information, which is read and decoded by the reader and then sent to the computer host for related processing.