High Power Amplifiers are used to amplify a signal before it is transmitted to the satellite. There are various mechanical means to amplify a signal before uplinking it to the satellite. Which type of amplifier you chose depends on a number of factors. Linearity, efficiency, reliability and cost are major considerations in an uplink design.
The three types of amplifiers are:
Klystron Power Amplifiers (KPA)
Traveling Wave Tube Amplifiers (TWTA)
Solid State Power Amplifiers (SSPA)
The high-power amplifier (HPA) provides the RF power for a payload downlink. Before the signal goes to the HPA, the preamplifier boosts the signal to a level proper for input to the HPA. We may call these two together the HPA subsystem. There are two types of HPA subsystem: the traveling-wave tube amplifier(TWTA) subsystem and the solid-state power amplifier (SSPA).
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