The main frequency ranges in the ISM band are as follows.
1, frequency 6.78MHz.
This frequency range of 6.765 ~ 6.795MHz, belonging to the short-wave frequency, this frequency range in the international has been assigned by the International Telecommunication Union as the ISM band to use, and will be more and more by the use of RFID systems.
This band was initially set up for short-wave communications, according to the propagation characteristics of electromagnetic waves in this band, short-wave communications during the day can only reach a very small role in the distance, up to a few hundred kilometers, the night can be spread across the continent. Users of this frequency range are different categories of radio services, such as radio broadcasting services, radio meteorological services and radio aviation services.
2, frequency 13.56MHz.
This frequency range is 13.553 to 13.567MHz, which is in the short-wave band and also the ISM band. In this frequency range, in addition to inductively coupled RFID systems, there are other ISM applications such as remote control systems, remote control modeling systems, demonstration radio systems and pagers.
This frequency band was also initially set up for shortwave communications, and based on the propagation characteristics of electromagnetic waves in this band, wireless signals allow for day and night transcontinental contact. Users of this frequency range are different categories of radio services, such as news organizations and telecommunication agencies.
3. Frequency 27.125 MHz.
. This frequency range is 26.957 to 27.283MHz. In addition to inductively coupled RFID systems, ISM applications in this frequency range include medical electrothermal therapeutic devices, industrial high-frequency welding devices and pagers. When installing an industrial 27MHz RFID system, special attention should be paid to any high-frequency welding devices that may exist in the vicinity. High-frequency welding devices generate very high field strengths, which will seriously interfere with RFID systems operating at the same frequency. In addition, when planning a 27MHz RFID system for hospitals, special attention should be paid to the possible existence of electrothermal therapeutic interference.
4, frequency 40.680MHz.
This frequency range of 40.660 ~ 40.700MHz, at the lower end of the VHF band, in this frequency range, the main application of ISM is telemetry and remote control.
In this frequency range, inductively coupled radio frequency identification of the role of the smaller distance, and this frequency 7.5m wavelength is not suitable for the construction of smaller and inexpensive backscatter electronic tags, so the band is currently no radio frequency identification system work, belongs to the radio frequency identification system is not very suitable for the frequency band.
5, frequency 433.920MHz.
This frequency range is 430.050 ~ 434.790MHz, in the world allocated to the amateur radio service use, this frequency band is located roughly in the middle of the amateur radio frequency band, at present has been occupied by the various ISM application. This frequency range belongs to the UHF band, and electromagnetic waves will experience significant attenuation and reflection when they encounter buildings or other obstacles.
This band can be used for backscatter RFID systems, in addition to small telephones, telemetry transmitters, wireless headsets, proximity low-power wireless radios, and automotive wireless central locking devices. However, in this band, due to the many applications, ISM's mutual interference is relatively large.
6, frequency 869.0MHz.
This frequency range is 868 ~ 870MHz, in the UHF band. Since 1997, this band in Europe allows short-range devices to use, and thus can also be used as RFID frequency. Some countries in the Far East are also considering allowing the use of this frequency range for short-range devices.
7, frequency 915.0MHz.
In the United States and Australia, the frequency range 888 ~ 889MHz and 902 ~ 928MHz has been available and is used by backscatter RFID systems. This frequency range is not yet available in Europe for ISM applications. The frequency range adjacent to this is occupied by cordless phones manufactured to the CT1 and CT2 standards.
8. Frequency 2.45 GHz.
This ISM frequency ranges from 2.400 to 2.483 5 GHz, which belongs to the microwave band, and is also in the UHF band, which partially overlaps with the range of frequencies used by amateur radio enthusiasts and radiolocation services. Electromagnetic waves in this band are quasi-optical propagation, buildings and obstacles are good reflective surfaces, and electromagnetic waves attenuate greatly during transmission.
This frequency range is suitable for backscatter RFID systems, in addition to typical ISM applications in this band such as Bluetooth and 802.11 protocol wireless networks.
9, frequency 5.8 GHz.
This ISM frequency range is 5.725 to 5.875 GHz, which belongs to the microwave band and partially overlaps with the frequency range used by amateur radio enthusiasts and radiolocation services.
Typical ISM applications in this frequency range are backscatter RFID systems, which can be used for highway RFID systems, and also for gate opening and closing (in stores or department stores) systems.
10, Frequency 24.125 GHz.
This ISM frequency range of 24.00 to 24.25 GHz is in the microwave band, which partially overlaps with the frequency ranges used by amateur radio enthusiasts, the radiolocation service, and the Earth resource satellite service.
No RFID systems currently operate in this frequency range, and this band is used primarily for mobile signal sensors, but also for radio directional systems that transmit data.
11, other frequency applications.
The frequency range below 135 kHz is not reserved as an Industrial, Scientific and Medical (ISM) frequency, and this band is heavily used by various radio services. In addition to the ISM frequencies, the entire frequency range below 135kHz RFID is also available, because this band can work with a larger magnetic field strength, especially suitable for inductively coupled RFID systems.