Multiport power amplifier: a flexible architecture for multi-channel amplification on board satellites [linearized TWTs]

Summary form only given. The amplification of multiple signals on board telecommunication satellites is normally implemented with one TWT per channel. Thus each TWT must be able to amplify the maximum peak power required for its channel, even though it is very unlikely that all channels will require the maximum power at the same time. A flexible architecture - the multiport power amplifier (MPA) (or Butler matrix) - solves this problem by sharing the power of several TWTs between the channels. The challenge lies in the paralleling of several TWTs whose insertion phase is very sensitive to voltage drifts. The strong non-linear characteristics of the TWTs also deteriorate the isolation between the channels. Hopefully, the advent of linearized TWTs (LTWT) at 20 GHz overcomes the linearity issue. We present the main LTWTA parameters relevant for the operation in the MPA and show experimental results of a matrix of two LTWTAs.