Circuit aspects of the NRL/industrial 94 GHz gyroklystron amplifier

A wide bandwidth, high average power W-band gyroklystron amplifier is currently under cooperative development by NRL, Litton Electron Devices, and Communication and Power Industries. The amplifier circuit is comprised of 4 stagger-tuned cavities operating in the fundamental TE/sub 011/ circular cavity mode. The input coupler is the first cavity of the circuit and must exhibit reasonable coupling strength between the TE/sub 10/ mode in the rectangular waveguide and the desired TE/sub 011/ circular cavity mode over a better than 600 MHz bandwidth centered at 93.4 GHz, with high TE/sub 01/ mode purity. A single WR-8 rectangular waveguide drives a combined coaxial/cylindrical cavity system. The coaxial cavity resonating in the TE/sub 411/ mode is tightly coupled to the cylindrical cavity, excited to resonate in the TE/sub 011/ mode. The RF magnetic field couples the cavities through 4 azimuthally spaced apertures.