Document Type : Scientific extension


Assistant Professor. Aerospace Research Institute, Ministry of Science, Research and Technology، Tehran، Iran


A communications satellite is an artificial satellite that relays and amplifies radio telecommunications signals via a transponder; it creates a communication channel between a source transmitter and a receiver on different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Communications satellites are usually composed of the following subsystems:1) Communication payload, normally composed of transponders, antennas, and switching systems; 2)Engines used to bring the satellite to its desired orbit; 3)Station keeping tracking and stabilization subsystem used to keep the satellite in the right orbit;4)Power subsystem, used to power the satellite systems, normally composed of solar cells; and 5)Command and control subsystem. There has been longstanding debate regarding the comparative reliability of solid-state power amplifiers (SSPAs) versus traveling wave tube amplifiers (TWTAs) for the satellite downlink. Many trade studies on comparing SSPAs and TWTAs rely on transistor device life test data on the ground for SSPAs due to the lack of statistically significant data on orbit. It is expected that the current on-orbit statistics in the industry shed relevant light on the debate.


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