Which frequency band is used for SATCOM transmissions?

• A. UHF frequencies
• B. VHF frequencies
• C. HF frequencies
• D. LF frequencies

Answer: (A)

SATCOM transmissions rely on a satellite relay, so you need a line-of-sight path to a satellite and a frequency band that allows a reasonably small, high-gain antenna on the aircraft. UHF bands are commonly used for satellite communications in aviation and military applications because they support compact antennas and offer reliable performance with the equipment typically carried on aircraft. VHF is used for air-to-ground voice and data within line-of-sight of ground stations, not for satellite links. HF and LF are favored for long-range, over-the-horizon communications that rely on ionospheric propagation, not satellites, so they’re not the standard choice for SATCOM. Therefore, among the given options, UHF frequencies best align with the typical needs of SATCOM transmissions on aircraft.