HF capabilities?

• A. It supports over-the-horizon communications
• B. It is only used for local ground-to-ground
• C. It cannot support NVIS
• D. It is primarily used for satellite communications

Answer: (A)

High-frequency communications enable long-range links by bouncing radio waves off the ionosphere, creating skywave paths that go beyond the horizon. That ionospheric reflection lets signals travel from one point on the globe to another far away without relying on satellites or a direct line of sight. This capability is fundamental for maintaining reach across continents and in environments where infrastructure is limited or contested.

This is why the statement about over-the-horizon communications best captures HF’s strength: it highlights the long-range, beyond-line-of-sight nature of HF links that come from skywave propagation.

HF can also be used for regional coverage with Near-Vertical Incidence Skywave, which sends signals at higher angles to cover nearby areas, so the claim that it cannot support NVIS isn’t accurate. And HF isn’t primarily used for satellite communications; satellites operate in different bands and rely on line-of-sight to orbiting platforms.