The radio frequency spectrum is the range of electromagnetic wave frequencies used for wireless communication. From AM and FM broadcasting to emergency services and satellite signals, virtually all modern wireless technology depends on this finite shared resource.
How Radio Frequencies Are Organised
Frequencies are measured in hertz (Hz) and organised into bands. Key broadcasting bands include:
- Medium Wave (AM): 530–1700 kHz — used for AM radio, capable of long-distance travel at night
- Very High Frequency (VHF): 87.5–108 MHz — home to FM radio, offering cleaner sound over shorter distances
- Ultra High Frequency (UHF): includes digital broadcasting and mobile data services
In the UK, Ofcom is the regulatory body responsible for allocating and managing spectrum licences. In the US, the Federal Communications Commission (FCC) performs this role. Both aim to prevent interference between broadcasters and ensure fair access.
Why Spectrum Is a Scarce Resource
Only a finite number of frequencies exist within usable ranges. With radio, television, mobile phones, Wi-Fi, aviation, and military communications all competing for space, careful management is essential. Without regulation, stations would overlap and render each other unintelligible.
Spectrum auctions, where mobile operators pay billions for access to particular frequency bands, demonstrate just how economically valuable this invisible resource has become.
What This Means for Radio Stations
A radio station cannot simply choose its own frequency. Broadcasters apply for licences specifying transmitter location, power output, and target coverage area. Adjacent stations in the same region must be far enough apart on the dial to avoid interference — a technical and regulatory balancing act that shapes the landscape of every local radio market.
Understanding spectrum helps explain why FM stations sound better close to a transmitter and why AM signals can sometimes be picked up from hundreds of miles away overnight — physics and licensing working together.