A shaped-reflector high-power converter for a whispering-gallery mode gyrotron output

A dual-shaped dual-reflector synthesis technique is applied to the design of a quasi-optical antenna system in a high-power microwave application for which the primary radiator is not conveniently described as a point source (spherical constant-phase surface). In addition, the output beam is required to be focused, and neither the entrance nor the exit pupil is conveniently described as being circular. The synthesis technique developed in this paper is a generalization of a well-established method which has found widespread application in the design of dual-shaped reflectors for satellite communication, radio astronomy, etc. Removing the usual assumptions of point-source illumination and parallel-ray output, as well as circular entrance and exit pupils, however, leads to expressions which may find application in a broader class of shaped-reflector designs. A reflector system has been designed using the general synthesis procedure which we have developed. The system transforms the right-hand rotating TE(15,2) mode propagating in 50.8 mm (2 in) diameter circular waveguide at 110 GHz into the HE(11) mode in 31.8 mm (1-1/4 in) diameter corrugated waveguide. A brief description of the experimental verification of the device performance is given.