Design Studies of Re-Entrant Square Cavities for V-Band Klystrons

V-band Klystrons find applications in satellite communications and 5G technology. Here, we present a V-band Klystron using radial re-entrant square cavities (RRSCs). The RRSCs are easy to fabricate, assemble, align, and tune to the operating frequency, which are significant concerns in V-band. We have optimized the number of cavities and the gap for best possible gain and bandwidth. The eigenmode and particle-in-cell (PIC) simulation results of the CST microwave studio are presented. The optimum design uses eleven equidistantly placed RRSCs, producing the maximum gain of 27.17 dB at 60.1 GHz with a bandwidth of ∼150 MHz.