The basic workflow of the working principle system is: the reader sends a certain frequency of RF signal through the transmitting antenna, and when the RF card enters the working area of the transmitting antenna, it generates induced current, which activates the energy obtained by the RF card; The RF card sends its own encoding and other information through the built-in transmission antenna of the card; The receiving antenna of the system receives the carrier signal sent from the RF card, which is transmitted to the reader through the antenna regulator. The reader demodulates and decodes the received signal, and then sends it to the backend main system for relevant processing; The main system judges the legitimacy of the card based on logical operations, makes corresponding processing and control for different settings, and sends command signals to control the action of the executing mechanism. There are fundamental differences in the coupling method (inductance electromagnetic), communication process (FDX, HDX, SEQ), data transmission method from RF card to reader (load modulation, backscatter, high-order harmonics), and frequency range among different non-contact transmission methods. However, all readers are similar in terms of functional principles and the resulting design and construction, All readers can be simplified into two basic modules: high-frequency interface and control unit. The high-frequency interface includes a transmitter and a receiver, and its functions include: generating high-frequency transmission power to activate the RF card and provide energy; Modulate the transmission signal to transmit data to the RF card; Receive and demodulate high-frequency signals from RF cards. There are some differences in the design of high-frequency interfaces between different RFID systems. The functions of the control unit of the reader include: communicating with the application system software and executing commands sent by the application system software; Control the communication process with the RF card (master-slave principle); Encoding and decoding of signals. For some special systems, there are additional functions such as executing anti-collision algorithms, encrypting and decrypting the data to be transmitted between the RF card and the reader, and performing identity verification between the RF card and the reader. The reading and writing distance of a wireless radio frequency identification system is a crucial parameter. The price of long-distance wireless radio frequency identification systems is still very expensive, so it is important to find ways to improve their reading and writing distance. The factors that affect the reading and writing distance of RF cards include antenna operating frequency, RF output power of the reader, reception sensitivity of the reader, power consumption of the RF card, Q value of the antenna and resonant circuit, antenna direction, coupling degree between the reader and the RF card, as well as the energy obtained by the RF card itself and the energy used to send information. The read distance and write distance of most systems are different, with the write distance being approximately 40-80% of the read distance