Long Range Certificate Course

Satellite antennas are not all the same. The type of antenna that will be used depends on the type of INMARSAT that will be connected to the antenna.
The Inmarsat B, M and Fleet are using parabolic dish antennas. These systems need a high signal strength that will be obtained by a dish antenna beaming into the direction of the satellite.

The INMARSAT C system uses an omni-directional antenna. This antenna receives and transmits in all directions and doesn't have to be pointed at the satellite's direction. For this reason the Inmarsat C antennas are much cheaper and easier to install because you don't need a complex antenna control and rotating system. The signal strength of this received/transmitted signal will be much weaker when you compare this to the parabolic dish antennas, and this is the reason for the limited capabilities of this INMARSAT C system.

The cable connections between terminal and antenna will be made by a coax cable. This coax cable will be of a higher quality when you compare this to the cables that are normally used in VHF or other equipment. Because of the SHF frequencies the Inmarsat equipment works on, there would be a great loss of signal strength if the normal coax cable had been used.