What is RFID technology

RFID, short for Radio Frequency Identification, is a technology closely related to radar. Its origins are evident in the word "Radio," indicating its connection to radio frequency communication. RFID emerged in the 1940s and 50s, developing from radar technology. It's a contactless data communication method that uses

 electromagnetic coupling between the tag and the reader's antenna for reading and writing. This is a two-way process: the reader can read the tag's content, decode it, and transmit the data to the backend system; it can also transmit information to modify the tag's content and status. Therefore, a complete RFID system consists of at least three parts: tags, readers, and a data system.         RFID can be categorized by frequency, including low-frequency, high-frequency, ultra-high-frequency, and microwave. Low-frequency and high-frequency RFID share the same induction principle: electromagnetic coupling. Coupling is achieved through a high-frequency alternating magnetic field in space, based on the law of electromagnetic induction. The radio frequency power ranges from 120kHz to 134kHz for low-frequency and 13.56MHz for high-frequency. Ultra-high frequency (UHF) induction utilizes electromagnetic backscatter coupling, a principle model similar to radar. The emitted electromagnetic waves reflect off the target, carrying back target information. This relies on the spatial propagation laws of electromagnetic waves, with a radio frequency power of 860-960MHz.         RFID can be further categorized into three main types based on the tag's power supply method: active RFID, passive RFID, and semi-active RFID. Passive RFID uses microwave signals transmitted from an RFID reader and energy from an electromagnetic induction coil to briefly power itself, thus completing the information exchange. Eliminating the power supply system allows for smaller tags. Active RFID is powered by an external power source and actively transmits signals to the RFID reader. These tags are typically larger but offer greater transmission distance and speed. Semi-active RFID uses a weak power source within the tag for data transmission during sleep mode. When the tag needs to be identified, the reader activates it by emitting a low-frequency signal, then uses a high-frequency signal to transmit data.        The RFID technologies we commonly use are passive low-frequency, high-frequency, and ultra-high-frequency (UHF) RFID. Due to the different information transmission methods, the signal strength, read/write distance, and operating environment also vary. Low-frequency RFID cannot penetrate metal environments, has the slowest transmission rate compared to other frequency bands, and a short read/write distance. Because it was developed earlier, it is mainly used in livestock management and simple access control systems. High-frequency RFID has a transmission rate between low-frequency and UHF. With anti-metal design, high-frequency RFID can be used in metal environments, has a longer read/write distance, and usually includes anti-collision design to improve anti-interference capabilities. It can read multiple electronic tags simultaneously. High-frequency RFID has matured significantly after a long period of development, with relatively stable reading performance and a wide range of applications, such as libraries, retail, logistics warehousing, healthcare, fixed assets, and archives. UHF RFID has the widest range and the fastest data transmission rate, but also higher energy consumption. Because it has a shorter development history, the technology is not yet mature or stable. Due to its superior reading speed and quantity, UHF RFID is typically used in situations requiring the reading of multiple tags at once. Regardless of the frequency band, RFID is based on the principle of electromagnetic induction, so it has strict requirements for the working environment. Electromagnetic interference from the surrounding environment will affect the reading performance.