Radio frequencies refer to the rate of oscillation of electromagnetic radio waves in the range of 3 kHz to 300 GHz. This band is used for communications transmission and broadcasting. Different radio frequencies are useful for different wireless technologies. For example, some frequencies are used for radio broadcasting, and others are used for television broadcasting.
Radio waves are used in many different types of communication, which are defined in the electromagnetic spectrum. The electromagnetic spectrum contains all the frequencies of electromagnetic waves, including visible light waves, microwaves, and radio waves. The radio wave spectrum is included in the electromagnetic wave spectrum, having a frequency range between 3 kHz and 300 GHz.
The radio frequency spectrum is divided into radio frequency bands for many applications, including AM Radio, FM radio, television, cellular networks, Bluetooth, walkie-talkies, satellite communications, and military applications. All wireless devices operate in the radio frequency range of the electromagnetic spectrum.
The International Telecommunication Union – Radiocommunication Sector (ITU-R) is responsible for allocating radio frequencies from the spectrum. The radio frequency bands are allocated for different purposes. Some bands in the electromagnetic spectrum are used for applications such as air traffic control and emergency responder communications networks. Some bands, such as the Industrial, Scientific, and Medical Band (ISM) and the unlicensed National Information Infrastructure (UNII) band, are license-free.
The frequency range for wireless communication is 3 Hz to 300 GHz. The WLANs, Bluetooth, cellular, and satellite communication all operate in the microwave UHF, SHF, and EHF ranges. The WLAN frequency is 2.4GHz ISM bands and 5 GHz UNII bands. Specifically, the following frequency bands are allocated to 802.11 wireless LANs:
- 4 GHz (UHF)- 802.11b/g/n/ad
- 5 GHz (SHF)- 802.11a/n/ac/ad
- 60 GHz(EHF) – 802.11ad
The components of the electromagnetic spectrum are gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, and radio waves. We will discuss radio waves in detail. Radio waves have the longest wavelengths, from a few centimeters to thousands of meters. The Tagle below illustrates the radio frequency band.
| Frequency Range | Band | Wavelength Range |
|---|---|---|
| Extremely Low Frequency (ELF) | 3 Hz – 30 Hz | 100,000 km – 10,000 km |
| Very Low Frequency (VLF) | 30 Hz – 300 Hz | 10,000 km – 1,000 km |
| Low Frequency (LF) | 300 Hz – 3 kHz | 1,000 km – 100 km |
| Medium Frequency (MF) | 3 kHz – 30 kHz | 100 km – 10 km |
| High Frequency (HF) | 30 kHz – 300 kHz | 10 km – 1 km |
| Very High Frequency (VHF) | 300 kHz – 3 MHz | 1 km – 100 m |
| Ultra High Frequency (UHF) | 3 MHz – 30 MHz | 100 m – 10 m |
| Super High Frequency (SHF) | 30 MHz – 300 MHz | 10 m – 1 m |
| Extremely High Frequency (EHF) | 300 MHz – 3 GHz | 1 m – 10 cm |
| Tremendously High Frequency (THF) | 3 GHz – 30 GHz | 10 cm – 1 cm |
| Very Tremendously High Frequency (VTHF) | 30 GHz – 300 GHz | 1 cm – 1 mm |
| Tremendously Very High Frequency (TVHF) | 300 GHz – 3 THz | 1 mm – 0.1 mm |
| Extremely Tremendously High Frequency (ETHF) | 3 THz – 30 THz | 0.1 mm – 0.01 mm |
| Very Extremely Tremendously High Frequency (VETHF) | 30 THz – 300 THz | 0.01 mm – 0.001 mm |
