Patent ID: 7719196

Claim:
A structure of a coaxial-to-waveguide transition, comprising: a waveguide for inputting or outputting a radio frequency wave; a vacuum envelope provided with a slow-wave circuit; a coaxial connection part connecting said waveguide and said vacuum envelope; an insulating and sealing member which is provided in said coaxial connection part, and which hermetically seats a side of said vacuum envelope and a side of said waveguide; a coaxial center conductor of an exterior portion with one end supported by said waveguide; and a coaxial center conductor of an interior portion with one end abutting on said slow-wave circuit and the other end connected to said coaxial center conductor of the exterior portion, wherein said waveguide is provided with a screw part supporting said coaxial center conductor of said exterior portion movably in an axial direction of said coaxial center conductor of said exterior portion, and an end portion of said coaxial center conductor of said exterior portion is connected to the other end of said coaxial center conductor of said interior portion movably in an axial direction of said coaxial center conductor of said exterior portion, wherein in said coaxial center conductor of said exterior portion, the end portion connected to said coaxial center conductor of said interior portion is projected to an interior of said waveguide with respect to the axial direction of said coaxial center conductor of said exterior portion, and said end portion is located in the interior of said waveguide.