High frequency window formed in a circular waveguide that is plastically deformable to adjust a waveguide length and manufacturing method therefor

A high frequency window, comprising:

• a circular waveguide that has a cylindrical section having a circular pipe conduit with a circular shaped cross section, and end wall sections joined to both sides in an axial direction of the cylindrical section;
• a first rectangular waveguide that has a first rectangular pipe conduit with a rectangular shaped cross section and that is joined to one of the end wall sections so that the first rectangular pipe conduit communicates with the circular pipe conduit;
• a second rectangular waveguide that has a second rectangular pipe conduit with a rectangular shaped cross section and that is joined to the other of the end wall sections so that the second rectangular pipe conduit communicates with the circular pipe conduit;
• and
• a dielectric plate that is configured as a plate shape, is disposed in the circular pipe conduit, and is airtightly held to the cylindrical section;
• wherein
• the circular waveguide has a plastically deformable section that is plastically deformable so that a length in an axial direction of the circular waveguide can be changed, wherein
• the plastically deformable section comprises a diaphragm that protrudes to an outer side in the axial direction of the circular waveguide, the diaphragm being disposed at a periphery of a predetermined part of one or both of the end wall sections;
• and
• the axial direction of the circular waveguide is the same direction as the axial direction of the cylindrical section.