what is LF,HF,UHF ?

For an RFID system, it is the concept of frequency reader through the antenna sending,receiving and reading the tag signal frequency range. Concepts from theapplication , the operating frequency of the RF tag is radio frequencyidentification system , directly determines the characteristics of varioussystem applications . In the RFID system, the system worked like we usuallylisten to FM radio , like RFID tags and readers have the same frequency can bemodulated to work .

RFIDtags operating frequency determine not only the working principle of radiofrequency identification system ( inductive coupling or electromagneticcoupling ) , recognition distance , but also determines the RFID tags andreaders to achieve the degree of difficulty and equipment costs. RFIDapplications or frequency band occupied by the internationally recognized ,that are located in ISM band . Typical operating frequencies : 125kHz, 133kHz,13.56MHz, 27.12MHz, 433MHz, 902MHz ~ 928MHz, 2.45GHz, 5.8GHz and so on.

Accordingto different frequency , RFID tags can be divided into low-frequency (LF), HighFrequency (HF), Ultra High Frequency (UHF) and microwave and other differenttypes . Different frequency bands for RFID works differently , LF, and HF bandsRFID tags generally using electromagnetic coupling principle , while RFID UHFand microwave bands generally using electromagnetic emission principle .Currently widely used in the frequency distribution in four kinds of bands ,low frequency (125KHz), HF (13.54MHz), UHF (850MHz ~ 910MFz) and microwave(2.45GHz). Each frequency has its own characteristics, are used in differentareas , so to proper use must first select the appropriate frequency.

Lowfrequency RFID tags , referred to as low-frequency tags , the operatingfrequency range of 30kHz ~ 300kHz. Typical operating frequency of 125KHz and133KHz. Low-frequency tags are generally passive tags , and its working energythrough inductive coupling from the reader 's radiating near-field couplingcoil obtained . Low-frequency tags and readers when transferring data betweenlow-frequency tag reader antenna must be located near field zone. Low-frequencytag reading distance under normal circumstances is less than 1 meter. Typicalapplications for low-frequency tags : animal identification , containeridentification , tool identification, electronic locking anti-theft ( withbuilt-in transponder car keys ) and so on.

Highoperating frequency band RF tag is generally 3MHz ~ 30MHz. Typical operatingfrequency of 13.56MHz. The band RFID tags , because it works exactly the samewith the low-frequency tags that use inductive coupling work, so should beclassified as low-frequency tags category. On the other hand , according to thegeneral division of radio frequencies , also known as high-frequency band ofits work , it is also often be referred to as HF tags . Given the band RFIDtags may be the most practical application of a large number of RFID tags , sowe simply high and low understood as a relative concept , that will not causeconfusion in understanding . For ease of description , we will call the IFfrequency tag . IF label generally passive design master , whose work with theenergy of low-frequency tags, also through inductive ( magnetic ) couplingcoupling coil from the reader to get near-field radiation . Tag and reader fordata exchange , the label must be in the reader antenna near-field region . IFtag reading distance under normal circumstances is less than 1 meter. IF labelcan easily be made because the card -shaped , widely used in electronic ticket, electronic / child / / certificates , electronic locking anti-theft (electronic remote lock controller ) , residential property management , buildingaccess control systems.

UHFand microwave frequency band referred to as microwave RFID tags RFID tags , thetypical working frequency 433.92MHz, 862 (902) MHz ~ 928MHz, 2.45GHz, 5.8GHz.Microwave radio frequency tags can be divided into two types of active tags andpassive tags . Work, the RF tag reader antenna radiation field in the far zonevenue, tags and readers for the coupling between the electromagnetic coupling.Reader antenna radiation field of passive tags to provide RF energy , theactive label wake . Corresponding radio frequency identification system readingdistance is generally greater than 1m, typical of 4m ~ 6m, up to 10m or more.Reader antennas are normally directional antenna , the reader only within adirectional beam antenna RF tag can be read / write. Since the increase inreading distance , the application may occur simultaneously in the reading areaof a plurality of RFID tags , and thereby proposed a multi- tag readsimultaneously needs. Currently , advanced radio frequency identification tagreader system are the multi- system is an important issue as a feature . UHFtag is mainly used for automatic identification of railway vehicles , containeridentification , but also for road vehicle recognition and automatic tollcollection systems.

Thecurrent level of technology , passive microwave RFID tags more successfulproducts are relatively concentrated in the working frequency band 902MHz ~928MHz . 2.45GHz and 5.8GHz radio frequency identification system mostly semi-passive microwave RFID tags products available. Semi- passive tags commonlyused button batteries , with a distant reading distance . The typicalcharacteristics of microwave radio frequency tags focused on whether passive ,wireless reading distance , whether to support multi-tag reading and writing,whether for high-speed recognition applications , the reader transmit powertolerance , RFID tags and reader prices, etc. . Can be written for the radiofrequency tag , the distance is usually less than the reading distance iswritten , the write request because the greater energy . Microwave radio tag datastorage capacity is generally limited to 2Kbits less, then a big storagecapacity does not seem to make much sense , from a technical and applicationstandpoint, microwave radio frequency tags are not suitable as a carrier oflarge amounts of data , and its main function is to identify items and completenon-contact recognition process. Typical data capacity indicators : 1Kbits,128Bits, 64Bits and so on. Auto-IDCenter developed by the Electronic ProductCode EPC capacity of 90Bits. Microwave radio tags Typical applications includemobile vehicle identification, electronic locking anti-theft ( electronicremote lock controller ) , medical research and other industries .

Differentfrequencies have different characteristics labels , for example , low-frequencytags cheaper than the UHF tags , to save energy , through the scrap metalobjects and strong , the operating frequency from radio frequency controlconstraints , the most suitable for a high water content of the object such asfruits, etc. ; UHF effect a wide range of data transfer speed, but more energy, less penetrating , work area can not have too much interference , suitablefor monitoring ports , warehousing and other logistics items ; while highfrequency identification tags are in short , read and write speed is centered ,the product price is relatively cheap , such as an application on the electronicticket card .

Currently, different countries for the same band , the frequency of use are not the same. Europe is using UHF 868MHz, the United States is 915MHz. Japan currently doesnot allow to use ultra high frequency radio frequency technology .

Currentlyin practice, the more commonly used is 13.56MHz, 860MHz ~ 960MHz, 2.45GHz otherbands. Close RFID system mainly uses 125KHz, 13.56MHz , etc. LF and HF bands ,the most mature technology ; range RFID systems primarily use 433MHz, 860MHz ~960MHz UHF band , etc. , as well as 2.45GHz, 5.8GHz and other microwave bands ,there is more in the test which there is no large-scale applications .

Chinain the LF and HF bands RFID tag chip design technology is relatively mature ,HF bands technical aspects of the design approach international advanced level, have been developed to meet ISO14443TypeA, TypeB and ISO15693 standard RFIDchip, and successfully applied to the transportation card and second /Generation / certificates and other items .