Line-of-sight is the unobstructed physical path a radio signal needs between a transmitter and a receiver. It matters in satellite links, spacecraft relays, microwave backhaul, and point-to-point wireless systems because buildings, terrain, weather, or the curve of the Earth can block or weaken the signal. When the path is clear, communication is usually stronger, faster, and more reliable.
In cyber security, line-of-sight is a security and operational constraint. Defenders must plan antenna placement, redundancy, and relay coverage so critical links do not fail when visibility is lost. Attackers may exploit this dependency by jamming, physically obstructing antennas, or positioning rogue equipment to intercept or spoof wireless traffic. For deep-space and remote networks, maintaining line-of-sight is part of preserving availability, integrity, and trust in the communication channel.