HF frequency range for communications is which?

• A. 30-3000 MHz
• B. 0.3-3 MHz
• C. 3-30 MHz
• D. 3-30 MHz

Answer: (C)

HF refers to the High Frequency band, which covers 3 to 30 MHz. This range is used for long-range communications because those frequencies can be reflected by the ionosphere, creating a skywave that reaches distant receivers far beyond the line of sight. Conditions like time of day and solar activity influence how well this works, but when favorable, HF enables international and over‑the‑horizon contacts with relatively modest power. Frequencies above 30 MHz are typically line-of-sight VHF/UHF, while frequencies below 3 MHz have different propagation characteristics and aren’t as practical for broad, reliable voice communications in many scenarios. So the 3 to 30 MHz range is the HF band.