Patent ID: 7439822

Claim:
A waveguide substrate in which a dielectric-medium waveguide for propagating and coupling a high-frequency signal to a cavity waveguide is structured, comprising: a dielectric plate; and conductor layers disposed on first and second surfaces of said dielectric plate; a plurality of conducting posts arranged in two columns, and penetrating between said conductor layers on the first and second surfaces of said dielectric plate to electrically conduct between the conductor layers, wherein said dielectric-medium waveguide comprises said plurality of conducting posts in two columns, said conductor layers and a dielectric portion enclosed by said plurality of conducting posts in two columns and said conductor layers, said dielectric-medium waveguide further comprises a transition part for a transition of the high-frequency signal between said dielectric-medium waveguide and said cavity waveguide; and said transition part comprises: waveguide shutting-off conducting posts arranged in a line at positions shutting off an end of said dielectric-medium waveguide, and penetrating between said conductor layers on the first and second surfaces of said dielectric plate to electrically conduct between the conductor layers; and two slit-like regions which are cutouts of said conductor layer on said first surface of said dielectric plate and are disposed substantially in parallel to each other, a first of said two slit-like regions being disposed in a separated position from said waveguide shutting-off conducting posts by a first distance and a second of said two slit-like regions being disposed in a separated position from said waveguide shutting-off conducting posts by a second distance larger than said first distance, wherein said two slit-like regions are apart from each other by a distance corresponding to substantially a half of a wavelength of the high-frequency signal propagated in said dielectric-medium waveguide.