In this papers are introduced the very sensitive components of the ship’s antenna tracking sys-tem as the weakest chain of the Maritime Mobile Satellite Service (MMSS). Also are presented the complete components of Ship Earth Station (SES), such as antenna system and transceiver with peripheral and control subsystems independent of ship motion. The communications Mobile Satellite Antennas (MSA) for Maritime Satellite Communications (MSC) are relatively large and heavy, especially shipborne directional Inmarsat B and Fleet-77 antenna systems. Over the past two decades the directional antenna system, which comprises the mechanical assembly, the control electronic and gyroscope, the microwave electronic package and the anten-nas assembly (dish, arrays and steering elements), is reduced considerably in both physical size and weight. These reductions, brought about be greater EIRP from satellite transponders coupled with GaAs-FET tech-nology at the front end the receiver leading to higher G/N RF amplifiers, has made the redesigning, adopting and installing of shipborne antennas even on tracks and airplanes a reality.