As we know, we listen to the radio for the same reason, RFID tags and readers should be modulated to the same frequency to work. LF, HF, UHF to correspond to different RF frequencies. LF low frequency radio representatives, in around 125KHz, HF high frequency RF representatives, at about 13.56MHz, UHF UHF radio representatives in the 860 to 960MHz range.
For an RFID system, its band concept refers the reader through an antenna to send, receive and read the tag signal frequency range. Conceptually from the application, the operating frequency of the RF tag is a radio frequency identification system operating frequency directly determine the characteristics of the various aspects of system applications. In the RFID system, the system worked like we usually listen to FM radio, as radio frequency tags and readers should be modulated to the same frequency to work.
RFID tags not only determines the operating frequency of the radio frequency identification system works (or inductively coupled electromagnetic coupling), identification distance, but also determines the ease and facility cost RFID tags and readers to achieve. RFID applications occupy a frequency band or frequency division has recognized in the international arena, which is located ISM band. Typical operating frequencies: 125kHz, 133kHz, 13.56MHz, 27.12MHz, 433MHz, 902MHz ~ 928MHz, 2.45GHz, 5.8GHz and so on.
According to different operating frequencies, RFID tags can be divided into low-frequency (LF), High Frequency (HF), Ultra High Frequency (UHF) and microwave and other different types. RFID works different bands different, LF and HF band RFID tags using electromagnetic coupling general principle, while RFID UHF and microwave frequency bands commonly used electromagnetic emission principle. Currently widely used international frequency distribution in four kinds of bands, low frequency (125KHz), high frequency (13.54MHz), UHF (850MHz ~ 910MFz) and microwave (2.45GHz). Each frequency has its own characteristics, is used in different fields, and therefore to the proper use must first select the appropriate frequency.
Low frequency RF tag, referred to as low-frequency tags, the operating frequency range of 30kHz ~ 300kHz. Typical operating frequency of 125KHz and 133KHz. Low-frequency tags typically passive tags, which work by inductive coupling energy obtained from the radiating near-field coupling coil of the reader. When transferring data between the tag and the reader low frequency, low frequency tag reader antenna radiation must be located near-field region. Read LF tags of less than one meter distance under normal circumstances. Typical applications for low-frequency tags are: animal identification, container identification, tool identification, electronic anti-theft lock (car key with a built-in answering device) and the like.
High-frequency RFID tags operating frequency is generally 3MHz ~ 30MHz. Typical operating frequency is 13.56MHz. The band RF tag, because the low-frequency tag works exactly the same principle, namely by inductively coupled manner, so should be classified as low-frequency tag class. On the other hand, according to the general division of radio frequencies, also known as high-frequency band of its work, it is also often referred to as high-frequency tags. Given that the band RF tag may be the practical application of the maximum amount of a radio frequency tag, so we just high and low understood as a relative concept, that will not cause confusion in understanding. For ease of description, we will be referred to the IF frequency tag. IF tag generally provided passive master, its work with low-frequency tags, like energy, but also through the inductor (magnetic) coupling obtained from the radiating near-field coupling coil of the reader. When the tag and reader data exchange, the label must be in the reader antenna radiating near-field region. IF tag reading distance under normal circumstances is less than one meter. IF tag can be easily made since the card-shaped, widely used in electronic tickets, electronic / child // certificate, electronic locking anti-theft (electronic remote door lock controller), residential property management, building access control systems.
UHF and microwave band RF tag referred to as microwave radio frequency tag, its typical operating frequency of 433.92MHz, 862 (902) MHz ~ 928MHz, 2.45GHz, 5.8GHz. Microwave RFID tags can be divided into two types of active tags and passive tags. In operation, the RF tag reader antenna located coupling radiation field far zone field, tags and readers between the electromagnetic coupling. Reader antenna radiation field to provide radio frequency energy to passive tags, active tags will wake up. Radio frequency identification systems read the corresponding distance is generally greater than 1m, typically of 4m ~ 6m, up to 10m or more. General reader antennas are directional antennas, only in a radio frequency tag reader antenna orientation within the beam range can be read / write. Since the reading distance increases, the application might appear in the reading area, while a plurality of radio frequency tags, which made the demand for multi-tag read simultaneously. Currently, advanced radio frequency identification systems are multi-tag reading problems as an important feature of the system. UHF tag is mainly used in railway automatic vehicle identification, container identification, but also for road vehicle identification and automatic toll systems.
The current level of technology, passive microwave radio frequency tag of the more successful the product is relatively concentrated work on 902MHz ~ 928MHz band. 2.45GHz and 5.8GHz radio frequency identification system and many more semi-passive microwave radio tag products available. Semi-passive tags commonly used button batteries, has far reading distance. Typical features of microwave radio tags focused on whether a passive, wireless reading distance, support multi-tag reader that is appropriate to identify aspects of high-speed applications, the reader transmit power margin RF tag and reader prices, etc. . Can write for radio frequency tag, the write distance is usually less than the reading distance, the reason is that write requires more energy. Microwave radio frequency tag data storage capacity is generally limited to less than 2Kbits, another large storage capacity does not seem to make much sense, from the perspective of technology and application, the microwave radio frequency tag is not suitable as a carrier of large amounts of data, and its main function is to logo items and complete contact-free identification process. Typical data capacity indicators: 1Kbits, 128Bits, 64Bits like. Auto-IDCenter developed by the Electronic Product Code EPC capacity of 90Bits. Typical applications include mobile microwave radio frequency vehicle identification tag, an electronic locking anti-theft (electronic remote door lock controllers), medical research and other industries.
Different frequencies have different characteristics tag, for example, low-frequency tags cheaper than UHF tags, saving energy, and strong penetration of scrap metal object, the operating frequency from the radio frequency control constraints, the most suitable for high moisture content of the object such as fruit, etc; the role of a wide range of UHF transmit data faster, but more energy, penetration is weak, the work area can not have too much interference, suitable for monitoring port, warehousing and other logistics items; and high frequency identification tag belongs in short, read and write speed is centered, product prices are relatively cheap, such as used in the electronic ticket card.
Currently, different countries for the same band, the frequency of use are not the same. European super-high frequency using a 868MHz, the United States is 915MHz. Japan does not currently used in ultra-high-frequency radio technology.
Currently in the practical application, more commonly used is 13.56MHz, 860MHz ~ 960MHz, 2.45GHz and other bands. Proximity RFID system mainly uses 125KHz, 13.56MHz and other LF and HF bands most mature technology; long-range RFID system mainly uses 433MHz, 860MHz ~ 960MHz UHF band, etc., as well as 2.45GHz, 5.8GHz and other microwave band, yet more testing which, no large-scale applications.