For an RFID system , it is the concept of frequency by the reader antenna transmission , receiving and reading 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 determines the characteristics of the system application areas . In the RFID system, the system worked like we usually listen to FM radio as radio frequency tags and readers to have the same frequency modulation to work .
RFID tags not only determines the operating frequency of the RFID system works ( inductive coupling or electromagnetic coupling ) , the identification distance , but also determines the degree of difficulty and equipment costs RFID tags and readers to achieve. RFID applications or frequency band occupied by the division has recognized internationally, 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 frequency , RFID tags can be divided into low-frequency (LF), high frequency (HF), Ultra High Frequency (UHF) and microwave and other different types . RFID works differently in different frequency bands , LF and HF band RFID tags generally using electromagnetic coupling principle , while RFID UHF and microwave bands generally using 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, are used in different areas , so to proper use must first select the appropriate frequency.
Low frequency RFID tags , referred to as low-frequency tags , the operating frequency range of 30kHz ~ 300kHz. Typical operating frequency of 125KHz and 133KHz. LF tag is generally passive tags , which work to obtain energy through inductive coupling from the radiating near -field coupling coil of the reader . When transferring data between the tag and reader low frequency , low-frequency tag reader antenna must be located near field radiation zone . Read the low frequency of less than one meter from the label under normal circumstances . Typical applications for the low-frequency tagged: animal identification, container identification, tool identification, electronic latching alarm ( car keys with built-in transponder ) and so on.
High operating frequency band RF tag is generally 3MHz ~ 30MHz. Typical operating frequency is 13.56MHz. The band RFID tags , because exactly the same principle to work with low-frequency tags that use inductive coupling work, so should be classified as low-frequency tags class. On the other hand , according to the general division of radio frequencies , also known as high-frequency bands of their work , it is also often referred to as high-frequency tags . Given that the band RFID tags may be the most practical application of a large number of RFID tags , so we just high and low understood as a relative concept , which does not cause confusion in understanding. For ease of description , we call IF RF tags . IF label generally passive design master , whose work with the energy of low-frequency tags, also through inductive (magnetic ) coupling obtained from the radiating near -field coupling coil of the reader . When 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 label can easily be made because the card-shaped , widely used in electronic tickets, electronic identity cards , electronic latching alarm ( electronic remote control door lock controller ) , residential property management , building access control systems.
UHF and microwave frequency band referred to as microwave radio frequency tag label , 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 . When working , the RF tag reader antenna coupling located in the radiation field inside the far zone , between the tag and reader electromagnetic coupling. Reader antenna radiation field to provide RF energy to passive tags , active tags will wake up . Appropriate radio frequency identification system reading distance is generally greater than 1m, typical of 4m ~ 6m, up to 10m or more. Reader antennas are directional antennas generally only in the RF tag reader antenna orientation within the range of the beam can be read / write. Since reading distance increases, the application may appear simultaneously in the reading area, a plurality of radio frequency tags , which made the need for multi-tag read simultaneously . Currently , advanced multiple RFID tag reading systems are an important issue as a feature of the system. UHF tag is mainly used in railway automatic vehicle identification , container identification , but also for road vehicle recognition and automatic toll systems.
The current level of technology , the more successful passive microwave RFID tags on products relative concentration of 902MHz ~ 928MHz operating frequency band . 2.45GHz and 5.8GHz radio frequency identification systems to semi-passive microwave radio multi- label products available. Semi- passive tags commonly used button batteries , with distant reading distance . Typical characteristics of microwave radio tags focused on whether passive , wireless reading distance , whether to support multi- tag reader , suitability aspects speed identification applications, the reader transmit power tolerance , RFID tags and readers , such as the price . Can write the wireless frequency tag , the distance is usually less than the reading from writing , the write request due to the greater energy . Microwave radio tag data storage capacity is generally limited to less than 2Kbits, then a large storage capacity does not seem to make much sense , from the perspective of technology and applications , the microwave radio frequency tags are not suitable as a carrier large amounts of data , and its main function is to identify the non-contact article and complete the identification process . Typical data capacity indicators : 1Kbits, 128Bits, 64Bits and so on. Developed by the Auto-ID Center 's Electronic Product Code EPC capacity of 90Bits. Typical applications of microwave radio frequency identification tags , including moving vehicles , electronic anti-theft lockout ( electronic remote control door lock controller ) , medical research and other industries .
Label different frequencies have different characteristics , such as low-frequency tags cheaper than UHF tags , saving energy , and strong penetration of scrap metal object , the operating frequency from radio frequency control constraints , the most suitable for high moisture component objects such as fruits, etc. ; UHF effect a wide range of data transfer speed, but more energy, penetration is weak , the operating area can not have too much interference for monitoring ports , warehousing and other logistics items ; while high frequency identification tag is in short , read and write speed is middling, 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 . Europe using a UHF 868MHz, the United States is 915MHz. Japan currently does not allow to use ultra high frequency radio frequency technology .
In present practice, the more commonly used is 13.56MHz, 860MHz ~ 960MHz, 2.45GHz other bands. Close RFID system is mainly used 125KHz, 13.56MHz , etc. LF and HF bands , the most mature technology ; distance RFID system mainly uses 433MHz, 860MHz ~ 960MHz UHF band , etc. , as well as 2.45GHz, 5.8GHz and other microwave bands , there is more in the test which , no large-scale applications.
China's technology in LF and HF band RFID tag chip design is relatively mature , HF bands aspects of design technology close to the international advanced level, has been developed in line with ISO14443 Type A, Type B and ISO15693 standard RFID chips , and successfully applied transportation card and second-generation ID cards and other items .