Patent ID: 7679475
Filing Date: 2010-03-16
Classification: H01P

Abstract:
1. A bandpass filter comprising: a laminate formed by stacking a plurality of dielectric layers; a first ground electrode arranged on a bottom surface of the laminate; a second ground electrode arranged on a top surface of the laminate; a plurality of strip-shaped first resonance electrodes arranged in parallel with each other on a first inter-layer portion of the laminate to be electromagnetically coupled with each other, each of the plurality of first resonance electrodes having a ground end and an open end, each of the ground ends being connected to a ground potential so that the plurality of first resonance electrodes function as a ¼ wavelength resonator; a strip-shaped input coupling electrode arranged on a second inter-layer portion of the laminate, different from the first inter-layer portion of the laminate, and overlapping more than half of the length of one of the plurality of first resonance electrodes corresponding to an input stage; a strip-shaped output coupling electrode arranged on a third inter-layer portion of the laminate, different from the first inter-layer portion of the laminate and overlapping more than half of the length of one of the plurality of first resonance electrodes corresponding to an output stage, wherein the input coupling electrode has a portion where an electrical signal inputted from an external circuit is supplied, the portion is located closer to the open end of the first resonance electrode corresponding to the input stage than the center of the input coupling electrode in the longitudinal direction, and the output coupling electrode has a portion where an electrical signal outputted to the external circuit is drawn, the portion is located closer to the open end of the first resonance electrode corresponding to the output stage than the center of the output coupling electrode in the longitudinal direction.