This paper outlines THALES ALENIA SPACE activities in the context of reconfigurable missions with channelized amplification in Ku-band. Flexibility in Tx pattern coverage is achieved thanks to an antenna including a shaped reflector and a focal array controlled by Ferrite phase-shifter. This paper focuses on the design of the focal feed array and details the guidelines that allowed to converge on a compact architecture.

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Demand for broadcasting services is likely to increase in the next years because of the emergence and growth of new services: Internet access, content delivery services and mostly HD-TV broadcasting. However satellite operators are also expressing a strong interest for flexible satellites, providing that satellites are cost effective. Flexible satellites allow fleet rationalization, optimization of back-up policy, and early entry in new or local markets. Flexibility in the coverage definition and power allocation appears as the best solution to follow the market evolutions and revolutions. Another concern of satellite operators is the cost effectiveness of the repeaters. Although, the craft of broadcasters was traditionally to broadly cast TV or radio programs to the largest audience, with the highest possible power, today trends go toward a geographic segmentation of the market. In this context, antennas, which are providing linguistic coverage, prevent broadcasting all over Europe by focusing power at the targeted audience. At antenna level, several technologies can answer to these requirements. Passive antenna technologies are able to provide some flexibility. However, active antennas appear to be the ideal tool to create multi-beam linguistic coverage, to introduce flexibility in beam pointing and shaping, to cope with changes of the orbital position of the satellite by adapting the coverage's shape, and finally to allocate dynamically the available radio power to beams. This paper reviews antenna active and passive technologies and the associated levels of flexibility. It then focuses on the description of an active antenna working in the Ka-band that is able to provide both HD-TV broadcasting and multimedia multicasting. These last technologies allow a complete flexibility and should be available for development after 2015.

This paper proposes a new wideband predistortion linearizer for TWTA enabling to use broadband multi-carrier signals for the new Telecom satellite transmit sections. The linearizer has been embedded in a channel amplifier equipment and successfully tested with a wideband Ku-band TWTA. A state-of-the-art NPR performance was obtained over the entire 10.7-12.75GHz Ku-band with multi-carrier signals up to 1GHz instantaneous bandwidth.

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