Design of an input coupler for a Ka-band second harmonic gyroklystron amplifier

A design of a coaxial input coupler with an outer TE/sub 811/ mode and inner TE/sub 021/ mode for the Ka-band second harmonic gyroklystron is presented in this paper. Simulation results from three-dimensional electromagnetic code show that 91% of the total energy is stored in the inner cylindrical cavity, and a circular TE/sub 021/ mode with high mode purity in an input cavity is obtained.