Patent US4263571A successfully refreshed from Google Patents.
US4263571A
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Surface acoustic wave filter
Assignee: Hitachi Ltd
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Filing: 1979-11-15
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Granted: 1981-04-21
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Expires: 1999-11-15
Abstract
Abstract A broad-band surface acoustic wave filter of turn reflector type in which the number N of thin film finger or stripe electrode pairs in at least one transducer is selected to satisfy N=F/k 2 to obtain a flat selected band in the frequency response, where F is the constant determined by the material of the used piezo-electric substrate and "k 2 " is the electro-mechanical coupling coefficient.
Inventors
- 👤 Yasuaki Kinoshita
- 👤 Mitsutaka Hikita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 04:51
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/64; H03H9/6489; H03H9/6496
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
131 words
A turn reflector type of surface acoustic wave filter comprising a transmitting transducer having a group of thin film finger or stripe electrodes on the surface of a piezo-electric substrate for converting a first electric signal to a surface acoustic wave, a receiving transducer having a group of thin film finger or stripe electrodes on the substrate for converting said surface acoustic wave to a second electric signal, and reflectors provided at both sides of said transmitting and receiving transducers; wherein the number N of the thin film finger electrode pairs in at least one of said transmitting and receiving transducers is selected so as to satisfy N≅F/k 2 , where F is the constant determined by the material of said substrate and "k 2 " is the electro-mechanical coupling coefficient.
Claim 2
Dependent Claim
131 words
A turn reflector type of surface acoustic wave filter comprising a transmitting transducer having a group of thin film finger or stripe electrodes on the surface of a piezo-electric substrate for converting a first electric signal to a surface acoustic wave, a receiving transducer having a group of thin film finger or stripe electrodes on the substrate for converting said surface acoustic wave to a second electric signal, and reflectors provided at both sides of said transmitting and receiving transducers; wherein the number N of the thin film finger electrode pairs in at least one of said transmitting and receiving transducers is selected so as to satisfy N≅F/k 2 , where F is the constant determined by the material of said substrate and "k 2 " is the electro-mechanical coupling coefficient.
Claim 3
Dependent Claim
37 words
The turn reflector type of surface acoustic wave filter as defined in claim 1 wherein said piezo-electric substrate is of lithiumniobate Y-cut propagation and said constant F determined by the substrate material is selected to be 1.5.
Claim 4
Dependent Claim
30 words
The turn reflector type of surface acoustic wave filter as defined in claim 1 wherein 3 dB directional couplers are provided between said transmitting and receiving transducers and said reflectors.
Claim 5
Dependent Claim
44 words
The turn reflector type of surface acoustic wave filter as defined in claim 1 wherein said each reflector consists of a plurality of grooves cut at a 45° angle with respect to the length of the stripe electrodes in said transmitting and receiving transducers.
References Cited (Backward Citations)
US3886504A
Cited
US4130813A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-04-20 | 1984-10-20 | 1985-04-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-04-20 | 1988-10-20 | 1989-04-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-04-20 | 1992-10-20 | 1993-04-21 | $7700.00 | Window Closed / Lapsed |