Highly Overmoded MM-wave Oscillator Experiments

Overmoded oscillator research has been an active area of interest at the University of Strathclyde for several years. Interaction structures based on complex electrodynamic structures can facilitate higher powers from overmoded mm-wave sources. The gain media used can be vacuum electronic, or condensed matter. The present work reports on the most recent experimental results using a vacuum electronic overmoded source in W-band (75-110 GHz). A two dimensional cylindrical slow wave interaction region is excited by an annular electron beam. Whereas in conventional sources the transverse dimensions of the slow wave structure (SWS) are comparable with the free space wavelength, in these experiments the structure diameter is approximately five free space wavelengths. Recent experimental progress is presented.