Medium power high efficiency Ka band

The paper shows a new generation high efficiency Ka- band TWT especially for high data rate signals which demands high output back-off operation. This TWT, named TL20075S, was not only designed for geostationary payloads but also for MEO orbits with electrical in orbit transfer (EOT). It is based on the well-known TL20073S Ka-band TWT. With this setup first time an average efficiency of more than 69% over 2.5GHz for saturation operation could be demonstrated. Simultaneously at 3 dB back-off operation with only half RF output power an average efficiency of more than 52%% over 2.5 GHz could be achieved. In this paper the new feasibilities of this efficiency improvement will be discussed. It could be used either for increased number of output channels, for significantly reduced thermal payload layout or for new ideas to omit a linearizer before the TWT for cost improvements. All together this design will give a high flexibility to the customer in his payload layout, as well as a changeability of orbit operation with flexible output power and flexible back-off adjustments. A broadband performance of 2.5 GHz extendable to 2.9GHz will give new standard Ka-band product for a wide operation usage.