US3753166A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Surface wave bandpass filter with non-linear fm input and output transducers and design method therefor
Assignee: Unisys Corp
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Filing: 1971-12-06
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Granted: 1973-08-14
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Expires: 1991-12-06
Abstract
Abstract A microwave acoustic surface wave bandpass filter comprises a piezoelectirc substrate with interdigital comb input and output transducers on the surface thereof. The spacing of the interdigital fingers of the input transducer is chosen to be a non-linear function of the distance along the transducer. Thus the input transducer is constructed to possess a non-linear frequency versus time response such that the amplitude versus frequency response thereof is the square root of the desired amplitude versus frequency response of the filter. The output transducer is constructed as a translated image of the input transducer thereby providing the matched filter thereof. The desired amplitude versus frequency characteristic of the filter is the square of the amplitude versus frequency characteristic of either of the transducers. A method for deriving the non-linear FM function that provides the desired amplitude versus frequency characteristic for the filter is disclosed.
Inventors
- 👤 J Worley
- 👤 R Price
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 01:39
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/02; H03H9/125; H03H9/145; H03H9/14517; H03H9/1452; H03H9/46; H03H9/64; H03H9/6423; H03H9/6426
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
83 words
A non-dispersive surface wave bandpass filter having a predetermined amplitude versus frequency characteristic comprising substrate means, input transducer means on siad substrate means constructed to have a plurality of parallel electrodes with interelectrode spacing varying in accordance with a substantially continuous non-linear frequency versus time characteristic, and output transducer means on said substrate means constructed as the translated image of said input transducer means, said non-linear frequency versus time characteristic being chosen to provide said predetermined amplitude versus frequency characteristic for said filter.
Claim 2
Dependent Claim
83 words
A non-dispersive surface wave bandpass filter having a predetermined amplitude versus frequency characteristic comprising substrate means, input transducer means on siad substrate means constructed to have a plurality of parallel electrodes with interelectrode spacing varying in accordance with a substantially continuous non-linear frequency versus time characteristic, and output transducer means on said substrate means constructed as the translated image of said input transducer means, said non-linear frequency versus time characteristic being chosen to provide said predetermined amplitude versus frequency characteristic for said filter.
Claim 3
Dependent Claim
42 words
The filter of claim 1 in which said input transducer means includes interleaved fingers, the inter-finger spacing thereof varying in accordance with a substantially continuous non-linear function of distance along said input transducer means, thereby providing said non-linear frequency versus time characteristic.
Claim 4
Dependent Claim
36 words
The filter of claim 1 in which said input transducer means comprises a non-linear FM pulse expansion filter, and said output transducer means comprises a non-linear FM pulse compression filter matched to said pulse expansion filter.
Claim 5
Dependent Claim
31 words
The filter of claim 2 in which said fingers aRe constructed and arranged with respect to each other to have an overlap grading to impart desirable characteristics to said bandpass filter.
Claim 6
Dependent Claim
39 words
The filter of claim 2 in which said fingers are constructed and arranged with respect to each other to have an overlap grading to compensate for the non-constant smapling rate of the time domain waveform by said transducer means.
Claim 7
Independent Claim
103 words
A method for designing a surface wave bandpass filter comprising the steps of determining the desired amplitude versus frequency characteristic for said filter, deriving a phase function of distance along the input transducer of said filter, the corresponding frequency versus time characteristic determining said amplitude versus frequency characteristic, disposing said input transducer on the substrate of said filter with the edges of the fingers thereof positioned in accordance with the distances determined by said phase function assuming values of integral multiples of pi /2, and disposing the output transducer of said filter on said substrate as, the translated image of said input transducer.
Claim 8
Independent Claim
103 words
A method for designing a surface wave bandpass filter comprising the steps of determining the desired amplitude versus frequency characteristic for said filter, deriving a phase function of distance along the input transducer of said filter, the corresponding frequency versus time characteristic determining said amplitude versus frequency characteristic, disposing said input transducer on the substrate of said filter with the edges of the fingers thereof positioned in accordance with the distances determined by said phase function assuming values of integral multiples of pi /2, and disposing the output transducer of said filter on said substrate as, the translated image of said input transducer.
Claim 9
Dependent Claim
26 words
The method of claim 6 in which said deriving step comprises the step of deriving said phase function in accordance with the principle of stationary phase.
Claim 10
Dependent Claim
38 words
The method of claim 7 in which said deriving step comprises the steps of substituting said desired amplitude versus time characteristic A( omega ) and the desired amplitude versus time characteristic a(t) for said filter in the equation
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-13 | 1977-02-12 | 1977-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-13 | 1981-02-12 | 1981-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-13 | 1985-02-12 | 1985-08-14 | $7700.00 | Window Closed / Lapsed |