What is the HF frequency range?

What is the HF frequency range?

• A. 3-30 MHz
• B. 3-30 GHz
• C. 30-300 MHz
• D. 300-3000 MHz

Answer: (A)

High Frequency communications use waves in the 3 to 30 MHz range. This band supports long-range, beyond-the-horizon links because the ionosphere can reflect these frequencies back to Earth, enabling skip and over-the-horizon transmission. The other ranges belong to different bands: 3-30 GHz is microwave territory and not HF; 30-300 MHz is VHF, typically used for line-of-sight VHF radio; and 300-3000 MHz is UHF, used for many terrestrial wireless systems. Therefore, 3 to 30 MHz is the correct HF range.

High Frequency communications use waves in the 3 to 30 MHz range. This band supports long-range, beyond-the-horizon links because the ionosphere can reflect these frequencies back to Earth, enabling skip and over-the-horizon transmission. The other ranges belong to different bands: 3-30 GHz is microwave territory and not HF; 30-300 MHz is VHF, typically used for line-of-sight VHF radio; and 300-3000 MHz is UHF, used for many terrestrial wireless systems. Therefore, 3 to 30 MHz is the correct HF range.