US3663899A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Surface-wave electro-acoustic filter
Assignee: Thales SA
•
Filing: 1970-04-02
•
Granted: 1972-05-16
•
Expires: 1990-04-02
Abstract
Abstract An electro-acoustic surface-wave (Rayleigh waves) device comprises a piezoelectric plate equipped with two transducers one at least of which is constituted by two comb-shaped electrodes having interleaved teeth. At least one of the electrodes have teeth of a dissimilar length the envelope of which is the curve representing the Fourier transform of the transfer function of the device when operated as a filter. The device finds application in the fields of radar, telecommunications, data processing, and the like.
Inventors
- 👤 Eugene Dieulesaint
- 👤 Pierre Hartemann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 07:49
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/02; H03H9/125; H03H9/145; H03H9/14517; H03H9/1452; H03H9/14526; H03H9/46; H03H9/64; H03H9/6423
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
111 words
A surface-wave electro-acoustic filter comprising a plate (3) of piezoelectric material; two transducers (1, 2) applied to said plate, at least one of which comprises two metal electrodes (1A, 1B) in comb-shaped form having interleaved teeth, at least one of the comb-shaped electrodes (1B) having teeth of dissimilar length, the envelope described by the tips of the teeth of said electrode being essentially the curve defining the Fourier transform of the transfer function of the device when operating as a fIlter; and the number of teeth in the electrode with dissimilar length teeth being sufficiently large for the envelope or envelopes to define the major undulations and lobes in said transform.
Claim 2
Dependent Claim
111 words
A surface-wave electro-acoustic filter comprising a plate (3) of piezoelectric material; two transducers (1, 2) applied to said plate, at least one of which comprises two metal electrodes (1A, 1B) in comb-shaped form having interleaved teeth, at least one of the comb-shaped electrodes (1B) having teeth of dissimilar length, the envelope described by the tips of the teeth of said electrode being essentially the curve defining the Fourier transform of the transfer function of the device when operating as a fIlter; and the number of teeth in the electrode with dissimilar length teeth being sufficiently large for the envelope or envelopes to define the major undulations and lobes in said transform.
Claim 3
Dependent Claim
58 words
A filter as claimed in claim 1, acting as a bandpass filter, wherein the envelope of the teeth of the combination of the envelopes of the teeth, is approximately the curve following the law described by the function y sin x/x ; x and y being coordinates respectively associated with the spacing and the lengths of said teeths.
Claim 4
Dependent Claim
16 words
A device as claimed in claim 1 wherein the piezoelectric plate (3) is made of quartz.
Claim 5
Dependent Claim
51 words
A device as claimed in claim 3, wherein the quartz plate (3) is X-cut and the electrodes are applied to the plate to obtain a direction of propagation of acoustic waves making an angle of about 30* with the Y axis; X and Y being crystallographic axes of said quartz plate.
Claim 6
Dependent Claim
17 words
A device as claimed in claim 1 wherein the piezoelectric plate (3) is made of cadmium sulphide.
Claim 7
Dependent Claim
19 words
A device as claimed in claim 1, wherein the pitch of said interleaved teeth is smaller than 10 microns.
Claim 8
Dependent Claim
33 words
A device as claimed in claim 1 wherein two adjacent teeth are connected to one and the same electrode at points (4) which correspond to a change in sign in the Fourier transform.
Claim 9
Dependent Claim
38 words
A device as claimed in claim 1 wherein more than one of the comb-shaped electrodes has teeth of dissimilar lengths, the combination of the envelopes of the tips of the teeth forming said curve defining the Fourier transform.
Claim 10
Dependent Claim
19 words
A device as claimed in claim 1 wherein the teeth of the comb-shaped electrodes are equidistant from each other.
Claim 11
Dependent Claim
19 words
A device as claimed in claim 7 wherein the teeth applied to the plate are equidistant from each other.
Claim 12
Dependent Claim
17 words
A device as claimed in claim 1, wherein the piezoelectric plate (3) is made of piezoelectric ceramic.
Claim 13
Dependent Claim
17 words
A device as claimed in claim 1, wherein the piezoelectric plate (3) is made of lithium methaniobate.
References Cited (Backward Citations)
US2759044A
Cited
US2922965A
Cited
US3150275A
Cited
US3310761A
Cited
US3376572A
Cited
US3446975A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |