Question 29C6

An Inmarsat Fleet Broadband RADOME houses the critical components for communicating with the satellite from a moving platform, such as a ship. 1. **Stabilized antenna:** This is crucial for maritime use. It includes the antenna element itself (often a patch array or helical antenna for L-band) and the mechanical system (gyroscopes, motors) that compensates for ship motion (pitch, roll, yaw) to keep the antenna continuously pointed at the geostationary satellite. 2. **RF unit:** This unit handles the radio frequency signals. It typically includes the Low Noise Amplifier (LNA) for receiving weak satellite signals and the High Power Amplifier (HPA) for transmitting signals back to the satellite. Placing the RF unit within the RADOME minimizes cable losses between the antenna and the transceiver. 3. **Antenna Control Unit (ACU):** This is the "brain" that processes data from the stabilization system and the GPS receiver to calculate the correct satellite look angle and command the motors to steer the antenna. 4. **GPS antenna:** The terminal's own position is vital for the ACU to determine the exact pointing direction for the geostationary satellite relative to the vessel's location. **Why other options are incorrect:** * **A) Phased array antenna** can be used, but many Fleet Broadband systems use mechanically steered patch or helical antennas. Also, it's less comprehensive than option B. * **C) and D) Parabolic dish antenna** is generally not used for L-band Inmarsat Fleet Broadband systems due to their larger size and beam characteristics; smaller, flatter antennas are preferred. **HV power supply** is also misleading. A **TDMA Control Unit** is part of the indoor modem unit, not typically within the outdoor RADOME itself.