An Introduction to the Radio Frequency Spectrum
The radio frequency (RF) spectrum is the range of electromagnetic radio frequencies used for wireless communications, broadcasting, radar, and other applications. It spans frequencies from 3Hz to 300GHz. This article provides an overview of the RF spectrum and its usage.
RF Spectrum Segments
The RF spectrum is divided into different ranges based on their utility:
- Very low frequency (VLF) - 3Hz to 30kHz. Used for submarine communications.
- Low frequency (LF) - 30kHz to 300kHz. Used for navigation and broadcasting.
- Medium frequency (MF) - 300kHz to 3MHz. AM broadcast radios operate here.
- High frequency (HF) - 3MHz to 30MHz. Shortwave broadcasting occurs here.
- Very high frequency (VHF) - 30MHz to 300MHz. FM radio, two-way radios, and television broadcasts use this band.
- Ultra-high frequency (UHF) - 300MHz to 3GHz. Cellular networks, WiFi, Bluetooth, and satellite communications predominately use this range.
- Super high frequency (SHF) - 3GHz to 30GHz. Radar systems and satellite links operate in this band.
- Extremely high frequency (EHF) - 30GHz to 300GHz. Millimeter wave wireless systems use this very high band.
RF Spectrum Allocation
Governments regulate and allocate different portions of the RF spectrum for various services based on technical criteria and demand. These allocations ensure efficient utilization and prevent interference.
Common designations include bands for broadcasting (AM, FM), mobile services (2G, 3G, 4G LTE), wireless LAN (WiFi), public safety, satellite usage, microwave links, and radio navigation. Unlicensed bands allow usage for low-power consumer devices.
With the growth in wireless services, efficient and optimal RF spectrum allocation is crucial for supporting new technologies and usage paradigms. Understanding the radio frequency spectrum enables leveraging it for innovative applications.
Radio signals are transmitted through electromagnetic waves, also called radio waves, in a radio communication system. The radio waves have a wide frequency range starting from a few ten kiloHertz (kHz) to several thousand Mega Hertz (MHz). This wide range of frequencies is called the radio spectrum or RF spectrum.
The RF spectrum is classified according to the applications of the spectrum in different service areas. The classification of the RF spectrum is given in the below table along with the associated applications in communication systems.
Classification of the Radio Frequency Spectrum
| Radiofrequency range | Wavelength (meters) Mass | Class | Applications |
|---|---|---|---|
| 10-30 kHz | 3 x 104 - 104 | Very Low Frequency (VLF) | Point-to-point communication (Long Distance) |
| 30-300 kHz | 104 - 103 | Low Frequency (LF) | Point-to-point communication (Long Distance) and Navigation |
| 300-3000 kHz | 103 - 102 | Medium Frequency (MF) | Radio broadcasting |
| 3-30 MHz | 102 - 10 | High Frequency (HF) | Overseas radio broadcasting, Point to Point Radio Telegraphy, and Telephony |
| 30-300 MHz | 10 - 1.0 | Very High Frequency (VHF) | FM broadcast, television, and Radar |
| 300-3000 MHz | 1.0 - 0.1 | Ultra-high Frequency (UHF) | Television and navigation |
| 3000-30,000 MHz | 0.1 - 0.01 | Super High Frequency (SHF) | Radar navigation and radio relays |