high power amplifier (HPA)

High Power Amplifiers (HPA) are microwave transmit amplifiers used in ground stations ofsatellite transmission systems. They amplify the microwaves so that they can be radiated from the parabolic antenna with an appropriate transmission power( EIRP).

HPA amplifiers use RF power transistors constructed as Travelling Wave Tube Amplifiers( TWTA) or Solid State Power Amplifiers( SSPA) and employ Travelling Wave Tubes( TWT), Metal Semiconductor Field Effect Transistors( GaAs- MESFET), High Electron Mobility Transistors( GaN- HEMT) or LDMOS transistors. They amplify microwaves in the frequency bands used for satellite communications. These can be frequencies in the S-band at 3 GHz, in the C-band at 6 GHz, in the X-band at 8 GHz or in the Ku-band at 14 GHz.

Solid State Power Amplifier (SSPA) for 5.8 GHz, photo: alibaba.com

The power range of the high power amplifiers is up to a few 100 W. In addition to the amplification factor, the power efficiency is a key characteristic of high power amplifiers. This can be 50% or more when using HEMTs.

HPA amplifiers amplify highly transformed frequencies which are fed to the parabolic antenna via waveguides or high-frequency cables.