Wireless tag technology is a non-contact automatic identification technology. It automatically recognizes target objects and obtains relevant data through radio frequency signals. The identification work can work in various harsh environments without manual intervention. Wireless tag recognition technology can recognize high-speed moving objects. It can identify multiple labels at the same time, and the operation is quick and convenient. RFID has the characteristics of waterproof, anti-magnetic, high temperature resistance, long service life, large reading distance, data encryption on the label, larger storage data capacity, and changeable storage information.
The key to RFID is that it allows for truly automated management of items without the need for scanning like barcodes. The RFID tag stores information that can be used interchangeably by the specification, and can be automatically collected to the central information system through the wireless data communication network. The RFID magnetic strip can be attached to the package in any form and does not require a fixed space like a barcode. On the other hand, RFID does not need to manually identify the tag, and the reader can read the location and product related data from the RF tag every 250ms.
When the system works, the reader sends a microwave inquiry (energy) signal. After receiving the microwave query energy signal, the electronic tag (passive) rectifies a part into a DC power supply for the circuit in the electronic tag, and another part of the microwave energy signal is tagged by the electronic tag. The stored data information is modulated (ASK) and reflected back to the reader. The reader receives the amplitude modulated signal reflected back, and extracts the identification data information stored in the electronic tag. During the working process of the system, the microwave signal emitted by the reader and The amplitude modulated signals received back reflected are simultaneously performed. The signal strength reflected back is much weaker than the transmitted signal, so the technical difficulty lies in the same frequency reception.
Electronic tag antenna
The following performance requirements must be met:
Sufficiently small enough to be made on an electronic tag that is already small;
Directionality with omnidirectional or hemispherical coverage;
Providing the largest possible signal to the chip of the electronic tag and providing energy to the tag;
Regardless of the direction of the tag, the polarization of the antenna can match the interrogation signal of the read head;
As part of the consumables, the price of the antenna must be very cheap.
VI. RFID application system
Low-frequency short-range RFID systems are mainly concentrated in 125kHz and 13.56MHz systems; high-frequency long-distance RFID systems are mainly concentrated in the UHF band (902-928MHz) 915MHz, 2.45GHz, 5.8GHz.
2. Working distance
For contactless payment applications, such as tickets in the bus system. The minimum distance among the multiple tags is the distance between the two passengers entering the car. For such systems, the optimal distance is 5-10 cm, and a larger distance may cause the system to read multiple tickets simultaneously.
3. Security requirements
Encryption and authentication.
4. Storage capacity
For applications that are price sensitive and require less on-site information, a fixed-coded read-only data carrier should be selected.
5. Multi-label simultaneous reading
Sometimes you need to consider the need for the system to recognize multiple tags at the same time.
6. Label packaging form
Sometimes for different working environments and operating conditions, the size of the label, the package form determines the performance of the label and the performance of the installation. The package form does not affect the performance of the work, but also affects the installation performance and aesthetic performance.