Line-of-sight propagation is commonly used for which type of links?

• A. VHF/UHF point-to-point links
• B. Deep-space radio links
• C. Submarine fiber links
• D. Satellite-only downlink

Answer: (A)

Line-of-sight propagation means the radio waves travel in a direct, unobstructed path between the transmitter and receiver, without relying on reflection from the ionosphere or diffraction around the Earth’s curvature. At VHF and UHF frequencies, the wavelengths are short enough that signals need a clear straight line between sites to maintain a reliable link. This makes VHF/UHF ideal for fixed, terrestrial point-to-point links where towers or hilltop sites are positioned to create an uninterrupted path, yielding predictable, high-quality connections over practical distances. Other options involve different media or vastly longer distances (space-based or undersea fiber), so the typical scenario described by line-of-sight propagation is those ground-based links in the VHF/UHF range.