Radio frequency identification (Radio Frequency Identification, RFID) technology is a non-contact automatic identification technology that uses the transmission characteristics of radio frequency signals through spatial coupling (inductive or electromagnetic coupling) or radar reflection to achieve contactless information transmission and achieve Identify the purpose. Radio frequency identification technology is widely used around the world. The obvious advantage over other technologies is that electronic tags and readers can be identified without contact.
The RFID system consists of five components, including: transmitter, receiver, microprocessor, antenna, and tag. Transmitters, receivers and microprocessors are usually packaged together, also known as readers, so the industry often divides the RFID system into three components: reader (reader), antenna (antenna) and tag (tag) .
Reader: A device that reads or reads/writes electronic tag information. The main task is to control the radio frequency module to transmit a read signal to the tag and receive the tag response, decode the tag's object identification information, and attach the object identification information to the tag. Other relevant information is transmitted to the host for processing.
Antenna: A transmitting and receiving device that transmits data between the tag and the reader.
Electronic tag (or radio frequency tag, transponder): composed of chip and built-in antenna. The electronic data stored in a certain format in the chip, as the identification information of the item to be identified, is the real data carrier of the radio frequency identification system. The built-in antenna is used to communicate with the RF antenna.
After the electronic tag enters the antenna magnetic field, if it receives a special radio frequency signal from the reader, it can send the product information (passive tag) stored in the chip by the energy obtained by the induced current, or actively send a signal of a certain frequency (Active tag), after the reader reads the information and decodes it, it is sent to the central information system for relevant data processing.
1. The reader sends a radio frequency signal of a certain frequency through the transmitting antenna;
2. When the RF card enters the working area of the transmitting antenna, an induced current is generated, and the RF card obtains energy and is activated;
3. The radio frequency card transmits its own code and other information through the card's built-in transmission antenna;
4. The system receiving antenna receives the carrier signal sent from the radio frequency card, and transmits it to the reader through the antenna regulator. The reader demodulates and decodes the received signal, and then sends it to the background main system for related processing;
5. The main system judges the legality of the card according to the logic operation, makes corresponding processing and control according to different settings, and issues command signals to control the action of the actuator.
RFID frequency is a very important parameter index of RFID system, which determines the working principle, communication distance, equipment cost, antenna shape and application field and other factors. Typical working frequencies of RFID are 125KHz, 133KHz, 13.56MHz, 27.12MHz, 433MHz, 860-960MHz, 2.45GHz, 5.8GHz and so on. According to the different operating frequencies, RFID systems are concentrated in three areas: low frequency, high frequency and ultra high frequency.
The higher the frequency, the farther the propagation distance, but the diffraction or penetration ability is weaker.
(Above article citation from luoxu34)