A High-Power $Ka$-Band (31–36 GHz) Solid-State Amplifier Based on Low-Loss Corporate Waveguide Combining

A method of using low-loss waveguide septum combiners is developed into a high-power $Ka$-band (31–36 GHz) amplifier producing $>$50 W at 33 GHz ($Ka$-band) using 32 low-power ($?$2 W) solid-state amplifier modules. By using low-loss waveguide combining and a packaged monolithic microwave integrated circuit with a low-loss microstrip-to-waveguide launcher, the output loss is minimized, allowing for the overall power-combining efficiency to remain high, $>$80% (average insertion loss of combiner $?$ 0.7 dB and average insertion loss of launcher $?$0.3 dB) over 31–36 GHz. In the past, lower power-combining efficiencies have limited the number of modules that can be combined at $Ka$ -band, and hence, have limited the power output. The approach demonstrated in this paper, with high power-combining efficiency, allows a very large number (32) of solid-state amplifier modules to be combined to produce high powers. Greater than 50 W was demonstrated with low power modules, but even higher powers $>$120 W are possible. The current approach is based on corporate combining, using low-loss waveguide septum combiners that provide isolation, maintaining the true graceful degradation of a modular solid-state amplifier system.