In satellite transmission, a transmission takes place between a satellite and a ground station. The satellite area is called the space segment, and the ground station area is called the ground segment. The transmission itself takes place using microwaves and is characterized by an extremely large transmission capacity.
In terms of connectivity, a satellite transmission can be a point-to-point link between earth station and satellite, or in the reverse direction between satellite and earth station, or as in the case of the Inter Satellite Link( ISL) between two satellites. Point-to-multipoint links can be established between satellites and mobile stations. The link from the ground station to the satellite is the uplink, and that from the satellite to the ground station is the downlink. Line-of-sight( LOS) is mandatory for transmission.
The transmission of the satellite radio to the terminal can refer to stationary, fixed, but also to mobile terminals. In addition, satellite services can also be used for broadcast communications. The disadvantages of satellite communication are the long delay times between the ground station and the satellite, which are caused by the long transmission paths, and the high attenuation due to the earth's atmosphere. Although the satellite transmission frequencies were selected at around 12 GHz so that the attenuation due to the earth's atmosphere is very low, the attenuation for the transmission link is over 100 decibels( dB). As a result, the received field strength is extremely low. It must be compensated by parabolic antennas and high- sensitivity RF amplifiers.