Patent ID: 7268648

Claim:
A dual mode band-pass filter comprising: a dielectric substrate having first and second main surfaces; a metallic film having one of a cross-shaped opening, an opening with bent portions and a plurality of openings, and disposed on the first main surface of the dielectric substrate or inside of the dielectric substrate; at least one ground electrode disposed on the second main surface of the dielectric substrate or inside of the dielectric substrate, so as to be opposed to the metallic film with the dielectric substrate disposed therebetween; and a pair of input-output coupling circuits connected to different portions of the metallic film; wherein the metallic film consists of only a single metallic film; the opening in the metallic film has a longitudinal dimension that extends in a direction that is substantially parallel to an imaginary line passing through connection points at which the pair of input-output coupling circuits are connected to the metallic film; the metallic film includes at least a first vertex and a second vertex; the first vertex and the second vertex are disposed at end portions of a first straight side of the metallic film; one of the different portions to which one of the pair of input-output coupling circuits is connected is located between the first vertex and the second vertex of the metallic film; a length of a first portion of the first straight side between the first vertex and the one of the different portions to which one of the pair of input-output coupling circuits is connected and a length of a second portion of the first straight side between the second vertex and the one of the different portions to which the one of the pair of input-output coupling circuits is connected are different from each other.