What is RFID technology?

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What is RFID technology? [Copy link]

RFID (Radio Frequency Identification) is a contactless automatic identification technology that automatically identifies target objects and obtains relevant data through radio frequency signals. It can quickly track items and exchange data, and its identification work does not require human intervention.

RFID, as a new technology, is a combination of radio technology and radar technology. In 1948, Harry Stockman published "Communication Using Reflected Power", which laid the theoretical foundation for radio frequency identification RFID. The technology that laid the foundation for RFID was developed during World War II. At that time, it was used to identify aircraft, also known as "friend or foe" identification technology. Subsequent versions of this technology are still used in aircraft identification today.

A typical RFID system consists of three main components: electronic tags, readers (including antennas) and application systems.

The electronic tag is the data carrier of the radio frequency identification system. It consists of a tag antenna and a tag-specific chip. It can receive the electromagnetic field modulation signal of the reader and return a response signal to realize the reading or writing operation of the tag identification code and memory data.

The reader/writer is used to receive commands from the host and transmit the data stored in the sensor back to the host via wired or wireless means. It contains a controller and an antenna. If the reading distance is long, the antenna will exist alone.

The application system refers to the user's original MIS system. The terminal computer of the application system that interacts with the RFID system transmits the work instructions issued by the application system, controls the coordination between the electronic tags and readers through the middleware, processes all the data collected by the RFID system, and performs calculations, storage and data transmission.

The working principle of the RFID system is: when an item with an electronic tag enters the radiation range of the reader antenna, it receives the wireless radio frequency signal sent by the reader. Passive electronic tags use the energy obtained by the induced current to send out the data stored in the tag chip, while active electronic tags actively send the data stored in the tag chip. The reader is generally equipped with a middleware with certain functions, which can read the data, decode it, and directly perform simple data processing, and then send it to the application system. The application system determines the legitimacy of the electronic tag based on logical operations, and performs corresponding processing and control according to different settings, thereby realizing the basic functions of the RFID system.

Radio frequency tag is also called radio frequency card, also known as contactless IC card. It consists of IC chip and induction antenna. The chip and antenna are not exposed and are encapsulated in a standard PVC card. The reading and writing process of radio frequency card is usually completed by radio waves between radio frequency card and reader/writer. It successfully combines radio frequency identification technology and IC card technology, solving the two major technical problems of passive and contactless, which is a major breakthrough in the field of electronic devices.

According to the power supply method of the tag, RFID tags can be divided into two forms: active and passive .

Active tags use energy provided by a power source within the tag and have a longer identification distance (can reach tens of meters or even hundreds of meters), but their lifespan is limited and their cost is high.

Passive tags do not contain a power source and obtain energy from the electromagnetic field of the reader when working. They are light in weight, small in size, long in life, and low in cost, but their communication distance is limited.

According to the different working frequencies, RFID systems can be divided into low frequency , medium and high frequency , ultra-high frequency and microwave systems .

The operating frequency of the low-frequency system is generally between 30KHz and 300KHz, and its typical operating frequencies are 125KHz and 133KHz. Its basic characteristics are low tag cost, small amount of data stored in the tag, short reading and writing distance (about 10cm), diverse tag shapes, and weak reading antenna directionality. It is mainly used in animal husbandry and animal management.

The operating frequency of the medium and high frequency system is generally between 3MHz and 30MHz, and its typical operating frequency is 13.56MHz. Its basic characteristics are low cost of tags and readers, large amount of data stored in tags, long reading and writing distance (up to 1m or more), strong adaptability, generally card-shaped, and both the reader and tag antenna have certain directionality. It is mainly used in the second-generation ID card system and the one-card system.

The operating frequency of UHF and microwave systems is generally between 300MHz and 3GHz or greater than 3GHz. The typical operating frequencies are 433MHz, 915MHz, 2.45GHz and 5.8GHz. According to the characteristics of each frequency band, it can be applied to different occasions.

For example, 433MHz active tags are often used in short-distance communication and industrial control. 915MHz passive tags are the choice in the logistics field. In addition to being widely used in short-distance communication, 2.45GHz is also widely used in my country's railway transportation identification management. The 5.8GHz RFID system is used as the working frequency band of my country's ETC and has taken the lead in formulating the national ETC standard.