Band-pass filter comprising a substrate enclosed by conductive layer pairs and a post wall to define a plurality of resonators having recesses of different depths

摘要

An object of the present invention is to prevent or reduce an error between a center frequency and a target center frequency in a coupled resonator band-pass filter which uses a post-wall waveguide. A band-pass filter (1) includes: a substrate (2) made of a dielectric substrate and sandwiched by a pair of conductor layers (3 and 4); and a post wall (11, 12) constituted by a plurality of conductor posts (11i, 12i) which pass through the substrate (2) and short-circuit the pair of conductor layers (3 and 4), the pair of conductor layers (3 and 4) and the post wall (11, 12) constituting a plurality of resonators (22 to 24) which are coupled, the pair of conductor layers serving as a pair of wide walls of the plurality of resonators, the post wall serving as a narrow wall of the plurality of resonator. The plurality of resonators include at least one resonator (22 to 24) which is provided with at least one recess (221 to 241) which passes through either one (the conductor layer 4) of the pair of wide walls and directly leads to inside the substrate (2).