Which range corresponds to HF communications?

Which range corresponds to HF communications?

• A. 30-300 MHz
• B. 3-30 MHz
• C. 0.3-3 MHz
• D. 300-3000 MHz

Answer: (B)

HF communications occupy the 3 to 30 MHz range. This band is distinctive because radio waves at these frequencies can reflect off the ionosphere and return to Earth, enabling long-distance, worldwide reach without satellites or extensive infrastructure. That skywave propagation is the defining feature of HF. The other ranges sit in different bands with different behavior: 30–300 MHz is VHF and is mainly line-of-sight, 30–3? MHz? is MF (roughly 0.3–3 MHz) which propagates differently and doesn’t give the same global reach, and 300–3000 MHz is UHF, which is also largely line-of-sight and used for different technologies. So the 3–30 MHz range is the correct match for HF communications.

HF communications occupy the 3 to 30 MHz range. This band is distinctive because radio waves at these frequencies can reflect off the ionosphere and return to Earth, enabling long-distance, worldwide reach without satellites or extensive infrastructure. That skywave propagation is the defining feature of HF. The other ranges sit in different bands with different behavior: 30–300 MHz is VHF and is mainly line-of-sight, 30–3? MHz? is MF (roughly 0.3–3 MHz) which propagates differently and doesn’t give the same global reach, and 300–3000 MHz is UHF, which is also largely line-of-sight and used for different technologies. So the 3–30 MHz range is the correct match for HF communications.