As a core component of radio frequency identification (RFID) technology, electronic labels enable contactless identification and transmission of object information through electromagnetic coupling. Their operating process can be divided into three key steps: energy activation, data modulation, and backscattering. Together, they form a wireless communication system that requires no physical contact and adapts to complex environments.
When an electronic label enters the electromagnetic field emitted by a reader, the antenna within the label senses the electromagnetic waves and generates an induced current. For passive electronic labels, this current directly powers the tag chip, activating it from its dormant state. Active electronic labels are powered by an internal battery, but the electromagnetic field still triggers signal transmission. The key to this stage is the efficiency of converting electromagnetic energy into electrical energy. The size, shape, and material of the tag antenna directly influence its energy capture capabilities. For example, antennas using flexible substrates can adapt to curved surfaces, while increasing the number of antenna turns can increase the induced voltage, ensuring stable operation in weak electromagnetic fields.
After activation, the electronic label must encode the stored information into an electromagnetic signal. Passive tags achieve this through backscatter modulation technology: the tag chip dynamically adjusts the antenna's impedance characteristics, changing the amplitude or phase of the reflected electromagnetic wave, thereby "embedding" binary data into the reflected signal. Active tags directly transmit modulated RF signals, achieving longer transmission distances but consuming more energy. Data encoding methods must balance efficiency and reliability. Manchester encoding is widely used in tag-to-reader communication due to its self-synchronization capability, effectively avoiding clock drift caused by long strings of "0s" or "1s."
The reader continuously transmits a fixed-frequency RF carrier through its antenna, creating an electromagnetic field covering a specific area. When the electronic tag enters this area, communication between the tag and the reader is established through inductive coupling or electromagnetic backscatter coupling. Inductive coupling is suitable for low- and high-frequency tags, transferring energy and data through a high-frequency alternating magnetic field in space. Typical applications include access control systems. Electromagnetic backscatter coupling is used in ultra-high-frequency and microwave tags, transmitting information by modulating the reflected carrier wave. It is suitable for long-distance scenarios such as logistics tracking. The choice between the two coupling methods depends on the application's requirements for read range, speed, and environmental adaptability.
Wireless transmission of electronic labels requires resolving multi-tag collision issues. When multiple tags simultaneously enter the reader's range, time division multiple access (TDMA) and frequency division multiple access (FDMA) technologies ensure orderly communication. TDMA assigns each tag a separate time slot to avoid signal overlap, while FDMA utilizes different frequency channels for parallel reading. Furthermore, a dynamic anti-collision algorithm automatically adjusts time slot allocation based on tag responses, significantly improving batch identification efficiency. For example, in warehouse inventory, the system can identify hundreds of tags per second, significantly reducing manual operation time.
Data security is a core guarantee for electronic label transmission. Encoding tag data using encryption algorithms prevents unauthorized access or tampering. Symmetric encryption technologies such as AES are suitable for resource-constrained tag chips due to their low computational complexity and high efficiency. Asymmetric encryption is used in high-security scenarios, such as financial payments. Furthermore, physical-layer security mechanisms such as random ID generation and signal interference suppression can further enhance attack resistance. For example, some e-wallets use dynamic key technology, generating a unique encryption code for each transaction, effectively preventing the risk of duplication.
The transmission performance of electronic labels is significantly affected by environmental factors. Metal surfaces reflect electromagnetic waves, causing signal attenuation. This requires the use of metal-resistant tags or adjustments to reader power. Liquid environments can absorb electromagnetic energy, necessitating optimized tag packaging materials. Temperature and humidity can also affect the stability of electronic components. Industrial-grade tags typically meet IP67 protection rating testing, ensuring reliable operation within a temperature range of -40°C to 85°C. Furthermore, the distance, angle, and relative speed between the tag and reader must be comprehensively considered during system design to achieve optimal transmission.
From logistics tracking to healthcare management, electronic label wireless identification and transmission technology is profoundly transforming the operations of various industries. Its contactless, efficient, and scalable nature not only improves data collection accuracy but also lays the foundation for the widespread adoption of the Internet of Things. With continued innovations in materials science, chip technology, and communication protocols, electronic labels will continue to evolve towards smaller size, lower power consumption, and higher security, becoming a core link between the physical and digital worlds.
