Patent ID: 8248977

Claim:
Apparatus for selectively directing downlink channels to downlink beams of a communications satellite, including: at least one multiport amplifier, the or each multiport amplifier comprising a plurality of microwave power amplifier units, a plurality of input ports and a plurality of output ports, the input ports and the output ports being connected to said amplifier units by signal dividing networks, so that an input signal at any input port is amplified by all amplifier units, and then recombined into an output signal at an output port, at least one output multiplexer, the or each output multiplexer comprising a plurality of input ports coupled via transmission lines to an output port, and each input port being coupled to the output port via a respective band pass filter, each said band pass filter having a predetermined pass bandwidth with guard bands between the pass band and adjacent pass bands of the output multiplexer, and the input ports of said one output multiplexer being selectively coupled to the output ports of said one multiport amplifier wherein said guard bands are dimensioned to be a predetermined width in frequency so as to compensate at least partially for cross-talk characteristics of said one multiport amplifier.