For an RFID system, its frequency band concept refers to the frequency range of the tag signal that the reader sends, receives, and reads through the antenna. From the application concept, the operating frequency of the radio frequency tag is also the operating frequency of the radio frequency identification system, which directly determines various aspects of the system application. In an RFID system, the system works just like we usually listen to FM radio, and the RF tags and readers have to be modulated to the same frequency to work.

The working frequency of the radio frequency tag not only determines the working principle of the radio frequency identification system (inductive coupling or electromagnetic coupling), the recognition distance, but also determines the difficulty level and equipment cost of the radio frequency tag and the reader. The frequency bands or frequencies occupied by RFID applications are recognized internationally, that is, in the ISM band. Typical operating frequencies are: 125 kHz, 133 kHz, 13.56 MHz, 27.12 MHz, 433 MHz, 902 MHz to 928 MHz, 2.45 GHz, 5.8 GHz, and so on.

Depending on the operating frequency, RFID tags can be classified into different types such as low frequency (LF), high frequency (HF), ultra high frequency (UHF), and microwave. The working principle of RFID in different frequency bands is different. RFID tags in LF and HF bands generally adopt the principle of electromagnetic coupling, while RFID in UHF and microwave bands generally adopt the principle of electromagnetic emission. At present, the frequencies widely used in the world are distributed in four kinds of bands, low frequency (125KHz), high frequency (13.54MHz), ultra high frequency (850MHz ~ 910MFz) and microwave (2.45GHz). Each frequency has its own characteristics and is used in different fields, so to use it properly, you must first select the appropriate frequency.

Low-band RF tags, referred to as low-frequency tags, have an operating frequency range of 30 kHz to 300 kHz. Typical operating frequencies are 125KHz and 133KHz. The low frequency tag is typically a passive tag whose operating energy is obtained by inductive coupling from the near field of the radiation of the reader coupling coil. When transmitting data 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 for low frequency tags are: animal identification, container identification, tool identification, electronic latching theft (car keys with built-in transponders).

The operating frequency of the mid-high frequency band RF tag is generally 3MHz ~ 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. Since the RF tag in this band may be the largest RF tag in practical applications, we only need to understand the high and low understanding as a relative concept, that is, it will not cause confusion. For ease of description, we refer to it as an IF RF tag. IF 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. Because the IF tag can be easily formed into a card shape, it is widely used in electronic tickets, electronic ID cards, electronic lockout anti-theft (electronic remote control door lock controller), residential property management, building access control systems, etc.

The radio frequency tags in the UHF and microwave bands are referred to as microwave radio frequency tags. The 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. At present, advanced RFID systems regard multi-label reading problems as an important feature of the system. UHF tags are mainly used for automatic identification of railway vehicles, container identification, and can also be used in road vehicle identification and automatic toll collection systems.

At the current state of the art, relatively successful products of passive microwave radio frequency tags are relatively concentrated in the operating frequency band of 902 MHz to 928 MHz. 2.45 GHz and 5.8 GHz RFID systems are mostly available with semi-passive microwave RF tags. Semi-passive tags are typically powered by button batteries and have a farther reading distance. The typical characteristics of microwave radio frequency tags mainly focus on whether passive, wireless read/write distance, whether to support multi-tag reading and writing, whether it is suitable for high-speed identification applications, the transmit power tolerance of readers, the price of radio frequency tags and readers, etc. . For wirelessly writeable RF tags, the write distance is usually less than the read distance because the write requires more energy. The data storage capacity of microwave radio frequency tags is generally limited to 2Kbits. The large storage capacity does not seem to have much significance. From the perspective of technology and application, microwave radio frequency tags are not suitable as carriers for large amounts of data. Their main function is Identify the item and complete the contactless identification process. Typical data capacity indicators are: 1Kbits, 128Bits, 64Bits, etc. The product electronic code EPC set by the Auto-ID Center has a capacity of 90 Bits. Typical applications for microwave radio frequency tags include mobile vehicle identification, electronic latching theft (electronic remote door lock controller), medical research and other industries.

Different frequency tags have different characteristics. For example, low frequency tags are cheaper than UHF tags, save energy, penetrate through scrap metal objects, and work frequency is not subject to radio frequency control. It is most suitable for objects with high water content. For example, fruits, etc.; UHF has a wide range of effects, and the data transmission speed is fast, but it is relatively energy-consuming, the penetration is weak, and the working area cannot have too much interference. It is suitable for monitoring items in the logistics fields such as ports and warehouses; The frequency tag is medium and short distance identification, the reading and writing speed is also centered, and the product price is relatively cheap, such as application on the electronic ticket card.

At present, different countries use different frequencies for the same band. The UHF used in Europe is 868MHz, and the U.S. is 915MHz.

Currently in practical applications, the commonly used frequency bands are 13.56MHz, 860MHz ~ 960MHz, 2.45GHz. The short-range RFID system mainly uses LF and HF frequency bands such as 125KHz and 13.56MHz, and the technology is the most mature; the long-distance RFID system mainly uses UHF frequency bands such as 433MHz, 860MHz to 960MHz, and microwave frequency bands such as 2.45GHz and 5.8GHz, and is still testing more. Among them, there is no large-scale application.

15 common RFID application areas:

1. Logistics:

Logistics warehousing is one of the most promising applications of RFID. UPS, DHL, Fedex and other international logistics giants are actively testing RFID technology, in order to enhance its logistics capabilities in large-scale applications in the future. Applicable processes include: cargo tracking in the logistics process, automatic information collection, warehouse management applications, port applications, postal parcels, express delivery, etc.

2. Retail:

RFID applications promoted by large supermarkets such as Wal-Mart and Metro will bring benefits such as reduced labor costs, improved visibility of goods, reduced losses due to out-of-stocks, and reduced product theft. Applicable processes include: real-time statistics of sales data of goods, replenishment, anti-theft, etc.

3. Manufacturing:

Real-time monitoring of production data used in production processes, quality tracking, automated production, and personalized production. It is more urgent to apply in the production of valuable and sophisticated goods.

4. Clothing industry:

It can be applied to the automatic production of garments, warehouse management, brand management, item management, channel management and other processes. With the reduction of label prices, this field will have great application potential. However, when applying, you must carefully consider how to protect your privacy.

5. Medical:

Can be applied to hospital medical device management, patient identification, baby theft and other fields. The medical industry is less sensitive to the cost of labels, so the industry will be one of the pioneers of RFID applications.

6. Identification:

RFID technology is widely used in personal identification documents due to its inherently fast reading and difficult forgery. For example, the e-passport projects currently being carried out in countries around the world, China’s second-generation ID cards, student ID cards and other various electronic documents.

7. Anti-counterfeiting:

RFID technology has characteristics that are difficult to forge, but how to apply it to anti-counterfeiting also requires active promotion by the government and enterprises. Areas that can be applied include: anti-counterfeiting of valuables (smoke, alcohol, medicine), anti-counterfeiting of tickets, etc.

8. Asset Management:

Various types of assets (precious or large similarities or dangerous goods, etc.)
As the price of the label decreases, almost all items can be involved.

9. Transportation:

High-speed no parking, taxi management, bus hub management, railway locomotive identification, etc.
There have been many successful cases. The application potential is great.

10. Food:

Preservation management of fruits, vegetables, fresh food, food, etc.
Because foods, fruits, vegetables, and fresh water contain a lot of moisture, which will affect normal label recognition, applications in this field will be innovative in the design and application of labels.

11. Animal Identification:

Training animals, livestock animals, pets and other identification management, animal disease tracking, individualized breeding of livestock animals.
There have been many successful cases in the international arena.

12. Library:

Bookstores, libraries, publishing houses, etc. Can greatly reduce the inventory of books, management time, can achieve automatic rent, borrow, return books and other functions. In the United States, Europe, Singapore and other existing library application success stories. There are libraries in the country that are being tested.

13. Automobile:

Manufacturing, anti-theft, positioning, car key
It can be applied to automobile automation, personalized production, car anti-theft, car positioning, and can be used as a safety key. There are successful cases in the world.

14. Aviation:

Manufacturing, passenger ticket, baggage tracking
Can be used in the manufacture of aircraft, maintenance and quality tracking of aircraft parts, passenger tickets, fast boarding, passenger tracking.

15. Military:

Identification and tracking of ammunition, guns, supplies, personnel, trucks, etc.
The United States has used it extensively in the Iraq war. The US Department of Defense has been tagging and identifying electronic tags for military supplies with its tens of thousands of suppliers.

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