An artificial satellite that uses a transponder to relay and amplify radio telecommunication signals is known as a communications satellite. It opens a channel for communication between a source transmitter and a receiver in different parts of the world. Television, telephone, radio, internet, and military applications all make use of communications satellites. There will be 2,224 communications satellites in Earth orbit on January 1, 2021. The majority of communications satellites are in geostationary orbits, which appear to be stationary at the same location in the sky and are 22,300 miles (35,900 kilometres) above the equator. As a result, ground station satellite dish antennas do not need to move to follow the satellite because they can aim permanently at that location. The Earth's curvature prevents the high-frequency radio waves used in telecommunications links from traveling straight ahead. The signal from communications satellites is transmitted around the Earth's arc to enable communication between geographically distant points. Radio and microwave frequencies are utilized by communications satellites in great detail. International organizations have rules about which frequency ranges, or "bands," certain organizations can use to avoid signal interference. There are two primary types of communications satellites: Passive and active. This allocation of bands reduces the likelihood of signal interference. Only the signal coming from the source, in the direction of the receiver, is reflected by passive satellites. Only a very small amount of the transmitted energy actually reaches the receiver with passive satellites because the reflected signal is not amplified at the satellite. The radio signal is attenuated by free-space path loss because the satellite is so high above Earth consequently the signal received on Earth is extremely weak. On the other hand, active satellites amplify the received signal before retransmitting it to the ground receiver. Passive satellites were the first communications satellites, but they are no longer used much. A project known as Communication moon relay resulted from the electrical intelligence gathering work that was started in 1951 at the United States Naval Research Laboratory. The creation of the longest communications circuit in human history, with the moon, Earth's natural satellite, serving as a passive relay, was the ultimate objective of this project. Military planners had long shown a lot of interest in secure and dependable communications lines as a tactical necessity. Telstar was the first active, direct relay communications commercial satellite and the first transatlantic transmission of television signals.

One more detached transfer try principally expected for military correspondences designs was task west passage, which was driven by Massachusetts Organization of Innovation's Lincoln Laboratory.  After an underlying disappointment in 1961, a send-off on 9 May 1963 scattered 350 million copper needle dipoles to make a latent reflecting belt. The project was able to successfully experiment and communicate using frequencies in the SHF X band spectrum, despite the fact that only about half of the dipoles were properly separated. Hughes Aircraft Company's Syncom 2, which was launched on July 26, 1963, was an immediate precursor to the geostationary satellites. The first communications satellite to be in a geosynchronous orbit was Syncom 2.  Its successor, Syncom 3, launched on July 19, 1964, was the first geostationary communications satellite.

John Gresham  
journal coordinator
international journal of innovative research in computer and communication engineering