Patent US3634788A successfully refreshed from Google Patents.
US3634788A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Waveguide filter
Assignee: International Standard Electric Corp
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Filing: 1967-09-27
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Granted: 1972-01-11
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Expires: 1987-09-27
Abstract
Abstract This invention relates to waveguide filters wherein waveguide sections functioning in the evanescent mode for frequencies in the desired passband are utilized to couple conventional cavity filter sections together. The evanescent sections operate in their normal modes at frequencies higher than the passband frequencies. Suppression devices are then coupled to one or more of the evanescent sections (instead of to the cavity filter sections) to suppress the parasitic harmonic waves while having negligible effect on the evanescent mode passband frequencies.
Inventors
- 👤 George Frederick Craven
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:56
CPC Classifications
H; H01; H01P; H01P1/00; H01P1/20; H01P1/219
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
134 words
A waveguide band-pass filter comprising: at least one waveguide section which is evanescent for the passband frequency of the filter, said waveguide section being dimensioned to propagate parasitic passband frequencies; at least a first and second resonator cavity filter section coupled together through said one evanescent waveguide section; a narrow-band absorption filter coupled to said evanescent waveguide section for suppressing parasitic frequencies, said absorption filter is of the constant resistance type and includes: at least two stubs; means including at least two broadband resonant slots for coupling said at least two stubs to said evanescent waveguide section; means coupled to one of said stubs for absorbing reflected energy from other of said stubs coupled to said evanescent waveguide section; at least one tunable screw coupled to the other of said at least two stubs.
Claim 2
Dependent Claim
134 words
A waveguide band-pass filter comprising: at least one waveguide section which is evanescent for the passband frequency of the filter, said waveguide section being dimensioned to propagate parasitic passband frequencies; at least a first and second resonator cavity filter section coupled together through said one evanescent waveguide section; a narrow-band absorption filter coupled to said evanescent waveguide section for suppressing parasitic frequencies, said absorption filter is of the constant resistance type and includes: at least two stubs; means including at least two broadband resonant slots for coupling said at least two stubs to said evanescent waveguide section; means coupled to one of said stubs for absorbing reflected energy from other of said stubs coupled to said evanescent waveguide section; at least one tunable screw coupled to the other of said at least two stubs.
Claim 3
Dependent Claim
135 words
A waveguide band-pass filter comprising: at least one waveguide section which is evanescent for the passband frequency of the filter, said waveguide section being dimensioned to propagate parasitic passband frequencies; at least a first and second resonator cavity filter section coupled together through sAid one evanescent waveguide section; a narrow-band absorption filter coupled to said evanescent waveguide section for suppressing parasitic frequencies, said absorption filter includes: a third cavity resonant at the parasitic frequency; a fourth cavity; means including a coupling hole in each of said third and fourth cavities to transfer energy at the parasitic frequency from said third cavity to said fourth cavity; a matched load coupled to said fourth cavity for absorbing said transfer energy; and a series rejection filter section coupling said third and fourth cavity to said evanescent waveguide section.
Claim 4
Dependent Claim
135 words
A waveguide band-pass filter comprising: at least one waveguide section which is evanescent for the passband frequency of the filter, said waveguide section being dimensioned to propagate parasitic passband frequencies; at least a first and second resonator cavity filter section coupled together through sAid one evanescent waveguide section; a narrow-band absorption filter coupled to said evanescent waveguide section for suppressing parasitic frequencies, said absorption filter includes: a third cavity resonant at the parasitic frequency; a fourth cavity; means including a coupling hole in each of said third and fourth cavities to transfer energy at the parasitic frequency from said third cavity to said fourth cavity; a matched load coupled to said fourth cavity for absorbing said transfer energy; and a series rejection filter section coupling said third and fourth cavity to said evanescent waveguide section.
Claim 5
Dependent Claim
111 words
A waveguide band-pass filter comprising: at least one waveguide section which is evanescent for the passband frequency of the filter, said waveguide section being dimensioned to propagate parasitic passband frequencies; at least a first and second resonator cavity filter section coupled together through said one evanescent waveguide section; a narrow-band absorption filter coupled to said evanescent waveguide section for suppressing parasitic frequencies, said absorption filter includes: a third cavity resonant at the parasitic frequency; an obstruction mounted within said third cavity for absorbing the parasitic frequency energy without having any significant effect on the passband energy; and a series rejection filter coupling said parasitic frequency cavity to said evanescent waveguide section.
Claim 6
Dependent Claim
111 words
A waveguide band-pass filter comprising: at least one waveguide section which is evanescent for the passband frequency of the filter, said waveguide section being dimensioned to propagate parasitic passband frequencies; at least a first and second resonator cavity filter section coupled together through said one evanescent waveguide section; a narrow-band absorption filter coupled to said evanescent waveguide section for suppressing parasitic frequencies, said absorption filter includes: a third cavity resonant at the parasitic frequency; an obstruction mounted within said third cavity for absorbing the parasitic frequency energy without having any significant effect on the passband energy; and a series rejection filter coupling said parasitic frequency cavity to said evanescent waveguide section.
Claim 7
Dependent Claim
13 words
A filter according to claim 3 wherein said obstruction includes an absorption screw.
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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) | 1975-01-10 | 1975-07-12 | 1976-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-10 | 1979-07-12 | 1980-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-10 | 1983-07-12 | 1984-01-11 | $7700.00 | Window Closed / Lapsed |