Patent ID: 7250834

Claim:
A bandpass filter for a differential signal, comprising a dielectric body, a first line and a second line on a surface of the dielectric body or a first surface of an inner part of the dielectric body arranged symmetrically to each other with respect to a surface of symmetry crossing the first surface, a third line and a fourth line on another surface of the dielectric body or a second surface which is another surface of an inner part of the dielectric body and faces the first surface, arranged symmetrically to each other with respect to the surface of symmetry, and a fifth line and a sixth line arranged symmetrically to each other with respect to the surface of symmetry on the first surface, wherein, the first line, the second line, the fifth line, and the sixth line respectively have a line length equivalent to a quarter wavelength of a center frequency of a used band; the third line and the fourth respectively have line lengths equivalent to a half wavelength of a center frequency of a used band; the first line, the second line, the fifth line, and the sixth line respectively have one end as an input/output end, and the other end as an open end; both ends of each of the third line and the fourth line are open ends; the first line and the fifth line are arranged in a cascade manner with their open ends adjacent, and both are facing the third line; and the second line and the sixth line are arranged in a cascade manner with their open ends adjacent, and both are facing the fourth line.