Width extensional resonator and coupled mode filter

Claim 2

A piezoelectric resonator comprising: an elongated plate, at least a portion of which remote from the ends thereof is piezoelectric and adapted to vibrate in extension parallel to the width when subjected to an alternating electric field; a pair of electrodes on opposite surfaces of said plate located only at substantially the central portion of the length of said plate and extending substantially to the edges of said plate so that they are adapted to apply to a piezoelectric portion of the plate remote from the ends thereof an alternating electric field in a direction which will induce said width extensional vibrations, said electrodes establishing with said piezoelectric material adjacent thereto a piezoelectric resonator having a resonance frequency controlled by the width of the plate, and whereby energy trapping is achieved.

Claim 3

A resonator as described in claim 1 in which the electrodes are on the major surfaces of the plate.

Claim 4

A resonator as described in claim 1 in which the electrodes are on the long edge surfaces of the plate.

Claim 5

A resonator as described in claim 1 in which the plate comprises lead zirconate-lead titanate ceramic.

Claim 6

A resonator as described in claim 1 in which the plate is supported at end areas thereof by acoustic damping material.

Claim 7

A resonator as described in claim 1 in which the plate comprises X-cut quartz crystal with the width of the plate parallel to the Y axis of the crystal.

Claim 8

A piezoelectric bandpass filter comprising: an elongated plate having substantially uniform width, at least a portion of the plate remote from the ends thereof being piezoelectric and adapted to vibrate in extension parallel to the width when subjected to an alternating electric field; a plurality of pairs of electrodes on opposite surfAces of said plate located only at substantially the central portion of the length of said plate and extending substantially to the edges of said plate so that the electrodes of each pair are adapted to apply to a piezoelectric portion of the plate remote from the ends thereof an alternating electric field which will induce said width extensional vibrations, each pair of electrodes establishing with said piezoelectric material adjacent thereto a piezoelectric resonator having a resonance frequency primarily controlled by the width of the plate, and whereby energy trapping is achieved; and the spacing of adjacent pairs of electrodes being sufficiently small that acoustic coupling exists between adjacent resonators.

Claim 9

A piezoelectric bandpass filter comprising: an elongated plate having substantially uniform width, at least a portion of the plate remote from the ends thereof being piezoelectric and adapted to vibrate in extension parallel to the width when subjected to an alternating electric field; a plurality of pairs of electrodes on opposite surfAces of said plate located only at substantially the central portion of the length of said plate and extending substantially to the edges of said plate so that the electrodes of each pair are adapted to apply to a piezoelectric portion of the plate remote from the ends thereof an alternating electric field which will induce said width extensional vibrations, each pair of electrodes establishing with said piezoelectric material adjacent thereto a piezoelectric resonator having a resonance frequency primarily controlled by the width of the plate, and whereby energy trapping is achieved; and the spacing of adjacent pairs of electrodes being sufficiently small that acoustic coupling exists between adjacent resonators.

Claim 10

A filter as described in claim 7 in which the electrodes are on the major surfaces of the plate.

Claim 11

A filter as described in claim 7 in which the electrodes are on the long edge surfaces of the plate.

Claim 12

A filter as described in claim 7 in which the plate comprises lead zirconate-lead titanate ceramic.

Claim 13

A filter as described in claim 7 in which the plate is supported at end areas thereof by acoustic damping material.

Claim 14

A filter as described in claim 7 in which the plate comprises X-cut quartz crystal with the width of the plate parallel to the Y axis of the crystal.