Experimental Observation of Coherent Millimeter Wave Radiation in a Folded Waveguide Employed with a Gyrating Electron Beam

Abstract

The first experimental observation of a strong millimeter wave radiation from a gyrating electron beam propagating through an H-plane bend rectangular folded waveguide is reported. Measurements of power, frequency, and relative phase change of both forward- and backward-wave radiations verified that the oscillation originated from an absolute instability near a stop band of the second space harmonic. A high power radiation of 5.5 kW which corresponds to an electronic efficiency of 24% was observed at 32.8 GHz.