| 摘要 |
<p>A bandpass filter for a differential signal applicable to a device having a wide passband. The bandpass filter has a dielectric body, a first line and a second line arranged symmetrically to each other with respect to a plane of symmetry C, a third line and a fourth line arranged symmetrically to each other with respect to the plane of symmetry, and a fifth line and a sixth line arranged symmetrically to each other with respect to the plane of symmetry. The first line, the second line, the fifth line and the sixth line respectively have a line length equivalent to an odd integer multiple of a quarter wavelength of a centre frequency of a used band. The third line and the fourth respectively have line lengths equivalent to an odd integer multiple of a half wavelength of a centre 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. Low-pass filters for stopping a signal that is higher than a predetermined frequency may be respectively provided at input/output ends of the first line and the second line. Also disclosed is a multifrequency antenna which has a wideband antenna driven by a differential signal, and which uses at least one bandpass filter as above.</p> |
