Patent ID: 6977566

Claim:
A filter including three or more resonators each comprising a waveguide having an electromagnetic wave propagation region surrounded by conductors, wherein the resonators are arranged so that an electromagnetic wave enters through an input end into one of the resonators and exits through an output end from another resonator, the resonators are arranged so that a plurality of propagation paths of the electromagnetic wave in TE mode are formed between the input end and the output end, and the resonators each have a plurality of portions, the plurality of portions each including a rectilinear side in a cross section parallel to an H-plane, the resonators are arranged so that a rectilinear side of one resonator is shared with another resonator, the shared rectilinear sides form boundaries between resonators for electric and/or magnetic coupling between the resonators, and the boundaries between the resonators are in the general shape of the letter Y.