Broadband quasi-optical mode converters for high power microwaves

The electron cyclotron maser is a high-power step-tunable MM-wave source which produces conical TE^o_mn radiation distributions with complicated E-field structure and usually no field on the waveguide axis. For nearly all applications, which include radar systems, plasma heating by ECRH and plasma diagnostics, a well defined plane polarized pencil beam is required. Quasi-optical mode converters of the Vlasov (step-cut) or Nakajima (obliquely-cut radiator) type can be used to convert the TE^o_mn output modes of the maser into a highly directional pencil beam. In applications this would allow the frequency of operation to be varied without need to change physically the mode conversion system