What is a satellite beacon?

A satellite beacon is a continuous or periodic transmission sent by the satellite itself. This signal usually contains telemetry data, which provides vital status information about the satellite's health, such as battery voltage, temperature, and system status. Beacons are incredibly useful for ground stations, even if they aren't actively transmitting to the satellite. They serve as a reliable reference signal to help operators locate the satellite, adjust for Doppler shift, and confirm the satellite is operational before attempting a two-way contact. The other options are incorrect because a beacon in the context of amateur radio is an RF transmission, not a physical component like an antenna, a reflective surface, or a visual indicator light.