A study of waveguide power combiner allowing for the variable number of input ports

A high power transmitter frequently consists of two or more SSPAs (Solid State Power Amplifier), and outputs of the power amplifiers are combined by a power combiner. However, when some power amplifiers fail, a power loss in the power combiner increases because the number of the input powers vary. In this paper, a waveguide power combiner allowing for the variable number of input ports is presented. The proposed power combiner is a tournament-shaped combiner in which lengths of lines between T junctions are an odd multiple of a 1/4 wavelength. When some amplifier stops, the powers of each amplifier can be combined with low loss in the proposed combiner, because the lines between the T junctions operate as impedance transformers. The proposed 8-way combiner is simulated and experimentally demonstrated in S-band. The power loss at six amplifiers is 0.25 dB in the experiments.