125 W Solid State Power Amplifier for 17.3-20.2 GHz SatCom Applications

This paper reports the design, realization and tests of the first prototype of a 125 W Solid State Power Amplifier (SSPA) based on spatial power combining technique for 17.3 GHz to 20.2 GHz SatCom applications. Sixteen 10 W high efficiency Gallium Nitride (GaN) Monolithic Microwave Integrated Circuits (MMICs) Power Amplifiers are combined through a low-lossy Radial structure developed in waveguide (WR-42). The MMICs are individually packaged and equipped with input/output microwave-to-waveguide hermetic transitions showing negligible losses. The Radio Frequency Tray (RFT) of the SSPA includes also a gain control unit, an analogue linearizer and a driver, while a waveguide coupler and an isolator are placed in sequence at the output. From 17.3 GHz to 20.2 GHz, the developed SSPA supplies more than 125 W of saturated output power with a gain and an overall efficiency better than 70 dB and 20%, while satisfying space constraints in terms of de-rating and reliability.