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Patent US4675631A successfully refreshed from Google Patents.
US4675631A
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US
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Waveguide bandpass filter
Assignee: Microwave Associates Inc
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Filing: 1985-01-17
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Granted: 1987-06-23
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Expires: 2005-01-17
Abstract
Abstract A waveguide bandpass filter having multiple waveguide sections including alternating ridge waveguide sections and evanescent waveguide sections. The ridge waveguide sections define a resonant cavity and the evanescent waveguide sections reactively load the resonant cavity thus intercoupling the ridge waveguide sections so as to provide a low loss filter having high attenuation, not only at adjacent stop band frequencies, but also at harmonics of the pass band.
Inventors
- 👤 Michael C. Waggett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:37
CPC Classifications
H; H01; H01P; H01P1/00; H01P1/20; H01P1/219
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
83 words
A waveguide bandpass filter comprising; multiple waveguide sections including alternating ridge waveguide sections and evanescent waveguide sections, each said ridge waveguide section defining a resonant cavity and comprising at least a single ridge waveguide section having the ridge extending from the waveguide broad wall, said evanescent waveguide section reactively loading said resonant cavity thus intercoupling said ridge waveguide sections to provide a low loss filter having high attenuation not only at adjacent stop band frequencies but also at harmonics of the pass band.
Claim 2
Dependent Claim
83 words
A waveguide bandpass filter comprising; multiple waveguide sections including alternating ridge waveguide sections and evanescent waveguide sections, each said ridge waveguide section defining a resonant cavity and comprising at least a single ridge waveguide section having the ridge extending from the waveguide broad wall, said evanescent waveguide section reactively loading said resonant cavity thus intercoupling said ridge waveguide sections to provide a low loss filter having high attenuation not only at adjacent stop band frequencies but also at harmonics of the pass band.
Claim 3
Dependent Claim
30 words
A waveguide bandpass filter as set forth in claim 1 wherein the length of each resonant cavity is on the order of one-half guide wavelength at the center operating frequency.
Claim 4
Dependent Claim
18 words
A waveguide bandpass filter as set forth in claim 1 including tuning means associated with each resonant cavity.
Claim 5
Dependent Claim
23 words
A waveguide bandpass filter as set forth in claim 3 wherein said tuning means comprises a tuning screw for adjusting the center frequency.
Claim 6
Dependent Claim
28 words
A waveguide bandpass filter as set forth in claim 1 wherein the outer dimensions of the ridge waveguide section are different than that of the evanescent waveguide section.
Claim 7
Dependent Claim
27 words
A waveguide bandpass filter as set forth in claim 5 wherein the evanescent waveguide section is of smaller cross-sectional dimension than that of the ridge waveguide section.
Claim 8
Dependent Claim
30 words
A waveguide bandpass filter as set forth in claim 1 wherein the outer dimensions of the ridge waveguide section are substantially the same as that of the evanescent waveguide section.
Claim 9
Dependent Claim
50 words
A wave guide band pass filter as set forth in claim 1 wherein the lengths of the resonator sections is given by: ##EQU9## where λ g=guide wavelength, θ j =π-1/2(φ j-1 , j +φ j , j+1), φ=effective electrical length of the equivalent circuit of the evanescent waveguide coupling section.
Claim 10
Dependent Claim
79 words
A waveguide bandpass filter as set forth in claim 8 wherein the length of the evanescent waveguide section is given by: ##EQU10## where ##EQU11## B=the equivalent shunt susceptance of the evanescent waveguide coupling section, Yo=the characteristic admittance of the ridge waveguide section, X=the equivalent shunt reactance of the evanescent waveguide coupling section, Zo=the characteristic impedance of the ridge waveguide section, and a=the broad wall dimension of the evanescent waveguide section in the same units as λo (free space wavelength).
Claim 11
Dependent Claim
20 words
A waveguide bandpass filter as set forth in claim 1 including standard waveguide members at each end of the filter.
Claim 12
Dependent Claim
27 words
A waveguide bandpass filter as set forth in claim 10 including waveguide matching sections coupling each standard waveguide member to the alternating ridge and evanescent waveguide sections.
Claim 13
Dependent Claim
27 words
A waveguide bandpass filter as set forth in claim 11 wherein the waveguide matching sections couple to the ridge waveguide sections at either end of the filter.
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) | 1990-06-22 | 1990-12-22 | 1991-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-22 | 1994-12-22 | 1995-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-22 | 1998-12-22 | 1999-06-23 | $7700.00 | Window Closed / Lapsed |