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RFID technology

Warm hints: The word in this article is about 1570 and  reading time is about 15 minutes.  
Guidance: Radio Frequency Identification (RFID) is a wireless communication technology, which can identify specific targets and read and write related data through radio signals, without establishing mechanical or optical contact between recognition system and specific targets. This article mainly consists of four parts: what is the radio frequency identification system, the composition and working principle of the radio frequency identification system, the classification of the radio frequency identification system, the RFID and the Internet of Things.

What is the RF identification?

Radio Frequency Identification () is a wireless communication technology that can identify specific targets and read and write related data through radio signals without identifying the system. Establish mechanical or optical contact with specific targets. The most important advantage of RFID is non-contact identification, which penetrates the harsh environment of snow, fog, ice, paint, dirt and bar codes that are not available, and is extremely fast to read, in most cases less than 100 milliseconds.

The advantage of RFID technology is not in monitoring equipment and environmental conditions, but in “recognition.” That is, the corresponding processing is performed by actively recognizing an object that enters the magnetic field recognition range. The RF ID is not a sensor, it mainly identifies the marker by the unique ID number corresponding to the tag. The sensor is a detecting device that can sense the information measured by the , and can transform the detected information into an electrical signal or other desired form of information output according to a certain rule.To meet the requirements of information transmission, processing, storage, display, recording and control. It is the first step in achieving automatic detection and automatic control.

The composition and working principle of RFID

The composition of the radio frequency identification system

The radio frequency identification system is mainly composed of three parts: label, antenna, reading Device. In addition, a special application system is required to handle the reader recognition accordingly.

  • 1) Label:An electronic tag, or radio frequency tag, transponder, consists of a chip and an internal antenna. The electronic data in a certain format is stored in the chip as the identification information of the item to be identified, and is the data carrier of the radio frequency identification system. The built-in antenna is used to communicate with the RF antenna.
  • 2) 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 response of the tag, and perform object identification information on the tag. Decoding, the object identification information and other related information on the label are transmitted to the host for processing.
  • 3) Antenna: A transmitting and receiving device that transmits data between a tag and a reader.

The operating principle of RFID

After the electronic tag enters the antenna magnetic field, if it receives a special radio frequency signal from the reader, it can send out the energy obtained by the induced current. The product information (passive tag) stored in the chip, or actively transmitting a signal of a certain frequency (active tag), the reader reads the information and decodes it, and sends it to the central information system for data processing.

In addition, according to the coupling method of the RF signal between the reader and the tag, the communication between them can be divided into: Inductance coupling and electromagnetic backscatter coupling.

  • 1) Inductive coupling: According to the law of electromagnetic induction, coupling is realized by spatial high-frequency alternating magnetic field. Inductive coupling The method is generally suitable for short-range RFID systems working at medium and low frequencies.
  • 2) Electromagnetic backscatter coupling: According to the spatial propagation law of electromagnetic waves, the emitted electromagnetic waves are reflected after hitting the target, and are carried back. Corresponding target information. The electromagnetic backscatter coupling method is generally suitable for high-frequency, microwave-operated long-distance RFID systems.

Popular understanding, inductive coupling is mainly used in low frequency (LF) and intermediate frequency (HF) bands due to low frequency RFID systems. The wavelength is longer and the energy is relatively weak, so it mainly relies on close proximity sensing to read information. Electromagnetic backscatter coupling is mainly applied in high frequency (HF) and ultra high frequency (UHF) bands due to the high frequency wavelength. Short, high energy. Therefore, the reader antenna can radiate electromagnetic waves to the tag, and some of the electromagnetic waves are modulated by the tag and then reflected back to the reader antenna. After decoding, they are sent to the central information system for processing.

Identification System Classification

At present, according to the frequency range used by the RFID system, the RFID system can be divided into four application frequency bands: low frequency, high frequency, ultra high frequency and microwave.

ncies are 125 kHz and 133 kHz. Low-frequency tags are typically passive tags, and their operating energy is passed through the inductor. The coupling method is obtained from the near field of the radiation of the reader coupling coil. When the data is transmitted between the low frequency tag and the reader, the low frequency tag needs to be located in the near field region radiated by the reader antenna. The reading distance of the low frequency tag is generally less than 1 meter.

Typical applications: animal identification, container identification, tool identification, electronic closure, security, car keys with built-in transponders, etc.

High-frequency RF tags

The operating frequency of high-band RF tags is generally 3MHz to 30MHz. The typical operating frequency is 13.56 MHz. The RF tag in this band, because its working principle is exactly the same as the low-frequency tag, that is, it works by inductive coupling, so it should be classified as a low-frequency tag. On the other hand, according to the general division of the radio frequency, its operating frequency band is also called high frequency, so it is often referred to as a high frequency tag.

High-frequency tags are also generally passive, and their working energy is the same as that of low-frequency tags. It is also obtained by inductive (magnetic) coupling from the near-field of the coupled coil of the reader. When the tag exchanges data with the reader, the tag must be located in the near field region of the reader antenna radiation. The reading distance of the IF tag is generally less than 1 meter.

Typical applications: electronic ticket, electronic ID card, electronic lockout anti-theft (electronic remote control door lock controller), residential property management, building access control system, etc.

UHF, microwave radio frequency tags

The radio frequency tags in the UHF and microwave bands are referred to as microwave radio frequency tags.Typical operating frequencies are 433.92 MHz, 862 (902) MHz to 928 MHz, 2.45 GHz, and 5.8 GHz.

Microwave radio frequency tags can be classified into active tags and passive tags. In operation, the RF tag is located in the far field of the radiation field of the reader antenna, and the coupling between the tag and the reader is electromagnetic coupling. The reader antenna radiation field provides RF energy to the passive tag and wakes up the active tag. The reading distance of the corresponding RFID system is generally greater than 1 m, typically 4 m to 6 m, and the maximum is more than 10 m. The reader antennas are generally directional antennas, and only the radio frequency tags within the directional beam range of the reader antenna can be read/written. Due to the increase of the reading distance, it is possible to have multiple RF tags in the reading area at the same time, which raises the need for simultaneous reading of multiple tags.

Typical applications: automatic identification of railway vehicles, container identification, and can also be used in road vehicle identification and automatic toll collection systems.

RFID and Internet of Things

RFID is an important supporting technology for the Internet of Things to perceive the outside world. The sensor can monitor the sensing of various information,However, there is a lack of ability to identify items, and RFID technology has a strong ability to identify items. Therefore, for the development of the Internet of Things, both sensors and RFID are indispensable.

Without the ability of RFID to identify objects, the Internet of Things will not be able to achieve the highest ideal of Internet of Everything. Without the support of RFID technology, the application scope of the Internet of Things will be greatly limited. On the other hand, because RFID radio frequency identification technology can only realize the recognition of objects in the magnetic field range, its read/write range is affected by the distance between the reader and the tag. Therefore, improving the sensing capability of the RFID system and expanding the coverage capability of the RFID system are currently urgent problems to be solved. At the same time, considering the long effective distance of the sensor network can greatly expand the application range of RFID technology. In the future, the integration of RFID and sensor networks will be an inevitable direction.

As far as the development of RFID is concerned, the initial integration of RFID and sensor network applications has been realized in many industrial industries. The complementary advantages of the two complement each other are deepening the Internet application, and their integration And system integration will greatly promote the development of the entire Internet of Things industry.The application prospects are immeasurable.

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