US3813618A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Surface wave electromechanical filter
Assignee: Thales SA
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Filing: 1972-07-13
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Granted: 1974-05-28
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Expires: 1992-07-13
Abstract
Abstract The invention relates to a narrow band surface wave electromechanical filter, comprising arrays of radiator elements constituted by two sets of comb-shaped electrodes deposited upon the surface of a piezoelectric substrate; one of said arrays serves to excite vibrational surface waves, and the other serves to receive them; the spacing of the radiator elements is constant in each array and equal to a whole number of times the mean wavelength of operation and are either equal, or different from one another, in the two arrays; this results in a high performance narrow band filtering device.
Inventors
- 👤 P Hartemann
- 👤 E Dieulesaint
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 11:57
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/64; H03H9/6423; H03H9/6426; H03H9/02; H03H9/125; H03H9/145; H03H9/14517; H03H9/1452
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
116 words
A narrow-band electromechanical filter for high frequency signals comprising a piezoelectric substrate and applied to said substrate excitatory and receiver transducers arranged on a longitudinal axis at the surface of said substrate, each of which includes a set of two comb-shaped electrodes having interleaved conductive fingers arranged at right angles in relation to said longitudinal axis, fingers of similar order facing each other on mutually overlapping opposite portions and defining an array of interdigital zones or radiator elements, the spacing between said radiator elements, or pitch of the array, being constant in each transducer and equal to a whole number of times the mean wavelength of operation, said whole number of times being greater than one.
Claim 2
Dependent Claim
116 words
A narrow-band electromechanical filter for high frequency signals comprising a piezoelectric substrate and applied to said substrate excitatory and receiver transducers arranged on a longitudinal axis at the surface of said substrate, each of which includes a set of two comb-shaped electrodes having interleaved conductive fingers arranged at right angles in relation to said longitudinal axis, fingers of similar order facing each other on mutually overlapping opposite portions and defining an array of interdigital zones or radiator elements, the spacing between said radiator elements, or pitch of the array, being constant in each transducer and equal to a whole number of times the mean wavelength of operation, said whole number of times being greater than one.
Claim 3
Dependent Claim
55 words
An electromechanical filter as claimed in claim 1, characterized in that said arrays have the same pitch, preliminary filter means being coupled to said filter; the transmitted frequency band of said preliminary filtering means is less than the reciprocal of the time taken by said surface wave to transit a distance equal to said pitch.
Claim 4
Dependent Claim
35 words
An electromechanical filter as claimed in claim 1, characterized in that the mutually opposite portions of the fingers of similar order belonging to each of said sets of comb-shaped electrodes, have equal overlapping opposite portions.
Claim 5
Dependent Claim
35 words
An electromechanical filter as claimed in claim 1, characterized in that the mutually opposite portions of the fingers of similar order, belonging to each of said sets of comb-shaped electrodes have dissimilar overlapping opposite portions.
Claim 6
Dependent Claim
31 words
An electromechanical filter as claimed in claim 1, characterized in that said surface is a flat surface containing said axis and said arrays of radiator elements are orientated along said axis.
Claim 7
Dependent Claim
51 words
An electromechanical filter as claimed in claim 1, characterized in that considering the excitatory transducers on the one hand and the receiver transducers on the other, the pitches of said arrays have different values; the smallest of said values is not contained a whole number of times in the other value.
Claim 8
Dependent Claim
41 words
An electromechanical filter as claimed in claim 6, characterized in that the difference between the reciprocals of said values is greater in absolute value than the reciprocal of the sum of the length of said arrays, said lengths being substantially equal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-27 | 1977-11-26 | 1978-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-27 | 1981-11-26 | 1982-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-27 | 1985-11-26 | 1986-05-28 | $7700.00 | Window Closed / Lapsed |