Abstract: A method of manufacturing a waveguide includes forming two waveguide units, each waveguide unit having a channel defined by a bottom wall and two side walls generally transverse to the bottom wall, flanges extending from the side walls, outside the groove, transverse to the side walls and generally parallel to the bottom wall, the flanges including though holes; joining the two waveguide units to each other so that the flanges of a first of the waveguide units abut the flanges of a second of the waveguide units, with the grooves forming a channel for guiding waves; and, by insert molding, forming a thermoplastic resin cover that fills the through holes in the flanges and covers both of the first and second waveguide units, at least partially.

Abstract: First and second members 1a, 1b, each having a U-shaped groove 20 of identical width and length, are joined together so as to constitute a waveguide channel while the U-shaped grooves 20 are opposed to each other. The first and second members 1a, 1b are fixedly fastened together by fastening bolts 2 and nuts 3 in the direction in which mating surfaces 5 are pressed together. Fastening force caused by the bolts 2 and the nuts 3 is depicted as circles 40 projected onto the mating surfaces 5 of the first and second members 1a, 1b. The bolts 2 and the nuts 3 are arranged such that lines of intersection (junction ridge lines) 6, each defined between a wall surface of the waveguide channel and the mating surface, are included in the respective projected circles 40.

Abstract: After through holes (25) are formed on flange portions (23) of a pair of waveguide units (20) and (21), and the pair of the waveguide units (20) and (21), in which the through holes (25) have been formed, are joined together, insert molding of the pair of the joined waveguide units (20) and (21) is executed using a thermoplastic resin to form a resin cover (30) filled into the through holes (25) and covers the pair of the waveguide units (20) and (21). Accordingly, an improved assembling efficiency, stronger fastening force between waveguide units, and better air-tightness of the waveguide are obtained by using resin molding to fasten the pair of the waveguides.