Multiport power combining transmitter for multibeam satellite communications

A multiple beam power combining transmitter which has the flexibility to adapt beam power to varying beam traffic is proposed. The new multiport power combining network consists of a power-dividing multiport directional coupler, multiple amplifiers and a power-combining multiport directional coupler. The multiport directional coupler consists of multiple quadrature hybrids. Since each amplifier commonly amplifies signals to each beam, the power allotment to each beam can be changed with flexibility. The concept and configuration of the multiport directional coupler which divides and combines input signals are described. Also, the effects of uneven gain and phase distribution or failure of amplifiers are represented theoretically. Implementation to 8-or 10-beam systems is shown. Finally, the characteristics of the 8-port experimental transmitter utilizing 1.5W FET amplifiers and branch line type hybrids are shown.