Geo-stationary & Communication Satellite

Geo-stationary Orbits:

     Geo-stationary satellite is the one whose orbital motion is synchronized with the rotation of the Earth. In this way the synchronous satellite remains always over the same point on the equator as the Earth spins on its axis. Such a satellite is very useful for worldwide communication, weather observations, navigation and other military uses 4.23 X 104 km is the orbital radius measured from the center of the Earth, for Geo-stationary satellite. A satellite above a particular point on the surface of the Earth. This height above the equator comes to be 36000 km.

Communication Satellite: 

       A satellite communication system can be set up by placing several geostationary satellites orbiting over different points on the surface of the Earth. One such such satellite covers 120 degree of longitude, so that whole of the populated Earth's surface can be covered by three correctly positioned satellites. The energy needed to amplify and retransmit the signals is provided by the large solar cell panels fitted on the satellites. There are over 200 Earth stations, which transmit signal to satellites and receive signals via satellite from other countries. The largest satellite system is managed by 126 countries, International Telecommunication Satellite Organization (INTELSAT). An INTELSAT VI operates at microwave frequencies of 4, 6, 11 and 14 GHZ and has a capacity of 30,000 two way telephone circuits plus three TV channels.