Band-pass filter and communication apparatus

A band-pass filter comprising a dielectric filter including:

• electrodes formed on both upper and lower surfaces of a substantially rectangular dielectric plate;
• and
• a plurality of sets of substantially rectangular non-electrode portions, each set of non-electrode portions facing across the dielectric plate, forming resonators in regions confined by the non-electrode portions on the dielectric plate,
• wherein the resonators are arranged so that electric fields for a resonance mode used by the resonators are oriented in the same direction, and adjacent resonators in the resonators are shifted by a predetermined value in a parallel manner to the orientation of magnetic fields for said resonance mode.

A band-pass filter comprising a dielectric filter including:

• electrodes formed on both upper and lower surfaces of a substantially rectangular dielectric plate;
• and
• a plurality of sets of substantially rectangular non-electrode portions, each set of non-electrode portions facing across the dielectric plate, forming resonators in regions confined by the non-electrode portions on the dielectric plate,
• wherein the resonators are arranged so that electric fields for a resonance mode used by the resonators are oriented in the same direction, adjacent resonators in the resonators are shifted by a predetermined value in a parallel manner to the orientation of magnetic fields for said resonance mode, and the longitudinal axes of said resonators are at a non-right angle with respect to the longitudinal and widthwise axes of the dielectric plate.

A band-pass filter comprising a dielectric filter including:

• electrodes formed on both upper and lower surfaces of a substantially rectangular dielectric plate;
• and
• a plurality of sets of non-electrode portions, each set of non-electrode portions facing across the dielectric plate, forming resonators in regions confined by the non-electrode portions on the dielectric plate,
• wherein at least some of the resonators other than input- and output-stage resonators are dual-mode resonators which resonate in a mode for which an electric field is oriented in the direction of alignment of the resonators, and in a mode for which an electric field is oriented in the direction perpendicular thereto, and adjacent dual-mode resonators are capacitively and inductively coupled with each other.