RFID system operate within specific bands within the radio spectrum. These bands are normally licence free bands enabling any system to use them.
Although licence free spectrum can be crowded in some areas, the short range nature of RFID means that these frequencies are normally very appropriate for RFID applications.
The particular band used for an RFID system is set during its design and it is not a user selectable item, although some bands may be selected according to the country in which it is used to conform to the licence free spectrum availability. This is normally factory set according to known area of sale. Typically band differences are only relatively small and do not affect the performance, and they only affect the UHF spectrum.
The frequency used by the RFID system determines many of the characteristics about the way in which it will operate. As a result, determining the correct RFID frequency band is an important early decision in the development process.
RFID frequency band / spectrum allocations
There four main RFID frequency bands within the radio spectrum that are used around the globe. These bands are placed widely different areas within the radio spectrum and this enables RFID to choose frequencies that will enable the right system parameters to be obtained.
|RFID Frequency Band / Spectrum Allocations|
|Typical Range||Typical RFID Applications|
|125-134.2 kHz and 140-148.5 kHz||Low frequency||Up to ~ 1/2 metre||These frequencies can be used globally without a license. Often used for vehicle identification. Sometimes referred to as LowFID.|
|6.765 - 6.795 MHz||Medium frequency||Inductive coupling is used on these RFID frequencies.|
|13.553 - 13.567 MHz||High Frequency
Often called 13.56 MHz
|Up to ~ 1 metre||These RFID frequencies are typically used for electronic ticketing, contactless payment, access control, garment tracking, etc|
|26.957 - 27.283 MHz||Medium frequency||Up to ~ 1 metre||Inductive coupling only, and used for special applications.|
|433 MHz||UHF||These RFID frequencies are used with backscatter coupling, for applications such as remote car keys in Europe|
|858 - 930 MHz||Ultra High Frequency
|1 to 10 metres||These RFID frequencies cannot be accessed globally and there are significant restrictions on their use. When they are used, it is often used for asset management, container tracking, baggage tracking, work in progress tracking, etc. and often in conjunction with Wi-Fi systems.
For further information on its use see the paragraph below.
|2.400 - 2.483 GHz||SHF||Backscatter coupling, but only available in USA / Canada|
|2.446 - 2.454GHz||SHF||3 metres upwards||These RFID frequencies are used for long range tracking and with active tags, RFID and AVI (Automatic Vehicle Identification). Backscatter coupling is generally used.|
|5.725 - 5.875 GHz||SHF||Backscatter coupling. Not widely used for RFID.|
858 - 930 MHz UHF RFID Frequencies
As the UHF RFID frequencies are not a global allocation, these frequencies cannot be used internationally. Where access is allowed, it may be found that there are different restrictions in different countries.
|UHF RFID Frequency Band Details|
|North America||Here the UHF RFID band can be used unlicensed within the limits of 915 MHz ± 15MHz (i.e. 902 - 928 MHz). There are restrictions on transmission power.|
|Europe (less exclusions)||Within this region, the RFID frequencies (and other low-power radio applications) specified ETSI recommendations EN 300 220 and EN 302 208, and ERO recommendation 70 03. These allow RFID operation within the band 865-868 MHz, but with some involved restrictions. RFID readers must to monitor a channel before transmitting - "Listen Before Talk".|
|France||The North American standard is not accepted within France as it interferes with frequencies allocated to the military.|
|China and Japan||There are no licence free RFID bands or frequencies. However it is possible to request a licence for UHF RFID which is granted in a site basis.|
|Australia & New Zealand||Within this area the RFID band exists between 918-926 MHz as these frequencies are unlicensed, but there are restrictions on the transmission power.|
As the allocated bands for RFID, particularly in the UHF portion of the spectrum may be different in different areas of the globe, it is necessary to include provision for this in the design. Fortunately the difference in the frequency bands is relatively small and can often be accommodated without major change to the RF design.
The variety of frequency bands available for RFID provides developers with a good choice. The difference in the properties along with the ways in which they can be used means that a variety of different coupling methods can be used.
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