The radio spectrum is the portion of the electromagnetic spectrum used for transmitting wireless signals. It’s divided into frequency bands, each with specific applications ranging from broadcast radio to satellite communications. Understanding the radio spectrum is essential for anyone involved in ham radio, monitoring, or general radio communication.
Spectrum Basics
The radio spectrum extends from about 3 Hz to 300 GHz, but practical communication usually occurs between 3 kHz and 300 GHz. Frequencies are grouped into bands, each suited for different types of communication.
Frequency Bands Overview
| Band | Frequency Range | Common Uses |
|---|---|---|
| VLF | 3–30 kHz | Submarine comms, time signals |
| LF | 30–300 kHz | Navigation, time signals |
| MF | 300–3000 kHz | AM broadcast, maritime, CB (upper end) |
| HF | 3–30 MHz | Shortwave, HF ham radio, marine, aviation over ocean |
| VHF | 30–300 MHz | FM radio, TV, ham radio, aviation, marine VHF |
| UHF | 300–3000 MHz | Cell phones, Wi-Fi, TV, GMRS/FRS, public safety |
| SHF | 3–30 GHz | Satellite, radar, microwave links |
| EHF | 30–300 GHz | Experimental, advanced radar |
Amateur Radio in the Spectrum
Ham radio operators have access to specific portions across multiple bands:
- HF Bands – 160m to 10m (1.8–30 MHz)
- VHF Band – 6m (50 MHz), 2m (144 MHz)
- UHF Band – 70cm (430–450 MHz)
- SHF and above – Advanced microwave frequencies for experimentation
These frequencies are used for:
- Local and global voice communication
- Morse code (CW)
- Digital data modes
- Satellite links
- Emergency communication
Band Plans and Allocations
Each region of the world is governed by frequency allocation rules. In the U.S., the FCC oversees spectrum use. The International Telecommunication Union (ITU) defines global guidelines.
Why Band Plans Matter
- Prevent interference between services
- Separate emergency and recreational frequencies
- Guide operators on where to transmit legally
Radio Services Across the Spectrum
Various services are assigned to distinct frequency bands:
- Broadcasting – AM, FM, TV (MF, VHF, UHF)
- Public Safety – Police, fire, EMS (VHF, UHF)
- Aviation – Civil and military (VHF airband)
- Marine – HF and VHF maritime bands
- Amateur Radio – Across HF, VHF, UHF, and above
- Satellite – SHF and higher for uplinks/downlinks
Propagation Characteristics
Each band behaves differently:
- HF – Reflects off the ionosphere for long-distance (skywave) communication
- VHF/UHF – Line-of-sight or affected by terrain; suitable for local or regional use
- SHF/EHF – High capacity, short-range, weather-sensitive; used for data, radar, satellite
Think of a long measuring tape
- AM Radio between ½-inch and 1.7-inches
- FM Radio between 88-inches and 108-inches
High Frequency spectrum
- High Frequency (HF spectrum) from 3 inches/MHz up to 30-inches (MHz)
- between about ½ -inch and 30-inches can reflect off the ionosphere
- Very-High Frequency (VHF spectrum) 30-inches up to 300-inches (MHz)
- 2-meter band 144 MHZ (or inches)
- Ultra-High Frequency (UHF spectrum) 300-inches and above
Understanding the radio spectrum helps hams and listeners alike navigate the airwaves legally and effectively. Whether you’re communicating across town on VHF or reaching across continents on HF, knowing where and how to operate is key to success in radio communications.