A Single-Stage Multimode Extended Interaction Circuit

A Ka-band single-stage extended interaction circuit capable of multimode amplification is studied to overcome the bandwidth limitation of the conventional extended interaction circuits with single-mode amplification. High-frequency features, particle-in-cell (PIC) simulation, and experimental study related to the multimode amplification are presented. The feasibility of the multimode amplification is indicated in the high-frequency simulation; a −3-dB bandwidth of more than 600 MHz (1.80% relative −3-dB bandwidth) using multiple operating modes is predicted by the PIC simulation; reflection and transmission features are verified by the experimental study. Furthermore, the high-order modes and the structural parameter sensitivity are analyzed.