US4673903A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Evanescent mode triple ridge lowpass harmonic filter
Assignee: Honeywell Ltd Canada
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Filing: 1984-11-02
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Granted: 1987-06-16
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Expires: 2004-11-02
Abstract
Abstract A waveguide lowpass filter has successive groups of three separate ridges spaced longitudinally in said filter. A center ridge of each filter has a larger cross-sectional area than two side ridges which are the same size. All ridges are parallel to one another in a longitudinal direction. The groups are associated with shunt capacitances and the spaces between adjacent groups are associated with series inductances in an evanescent mode. In operation, the filter is capable of supporting a TE10 mode in the passband and three modes, TE10, TE20 and TE30 in the stopband. The filter has a relatively high power handling capability as compared to previous evanescent mode lowpass harmonic filters.
Inventors
- 👤 Abdelmegid K. Saad
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:23
CPC Classifications
H; H01; H01P; H01P1/00; H01P1/20; H01P1/207; H01P1/211
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
123 words
A waveguide lowpass filter comprising a filter body with successive groups of three separate ridges formed therein, said groups being spaced longitudinally throughout said filter with spaces there between, all ridges being parallel to one another in a longitudinal direction, said groups being associated with shunt capacitances in a passband and stopband, said spaces between successive groups being associated with series inductances in an evanescent mode in the passband, each group having one centre ridge and two side ridges disposed transversely across said filter, with said side ridges being equally spaced from said centre ridge, said side ridges being smaller in width than said centre ridge, said filter being capable of supporting one mode in the passband and three modes in the stopband.
Claim 2
Dependent Claim
123 words
A waveguide lowpass filter comprising a filter body with successive groups of three separate ridges formed therein, said groups being spaced longitudinally throughout said filter with spaces there between, all ridges being parallel to one another in a longitudinal direction, said groups being associated with shunt capacitances in a passband and stopband, said spaces between successive groups being associated with series inductances in an evanescent mode in the passband, each group having one centre ridge and two side ridges disposed transversely across said filter, with said side ridges being equally spaced from said centre ridge, said side ridges being smaller in width than said centre ridge, said filter being capable of supporting one mode in the passband and three modes in the stopband.
Claim 3
Dependent Claim
34 words
A filter as claimed in claim 3 wherein the one mode in the passband is TE 10 and the three modes in the stopband are TE 10 , TE 20 and TE 30 .
Claim 4
Dependent Claim
25 words
A filter as claimed in claim 1 wherein said side ridges are identical to one another and are smaller in height than said centre ridges.
Claim 5
Dependent Claim
42 words
A filter as claimed in any one of claims 1, 3 or 2 wherein the centre ridges are top loaded with dielectric material between a top surface of each of said ridges and an interior surface of a cover for said filter.
Claim 6
Dependent Claim
41 words
A filter as claimed in any one of claims 1, 3 or 2 wherein all of the ridges are to loaded with dielectric material between a top surface of said ridges and an interior surface of a cover for said filter.
Claim 7
Dependent Claim
67 words
A filter as claimed in any one of claims 1, 3 or 2 wherein the series inductance=jX o sinh (γl) where ##EQU2## where: a is the broad wall dimension of the evanescent mode waveguide b is the narrow wall dimension of the evanescent mode waveguide λ is the free space wavelength λ c is the cut-off wavelength=2a l is the distance between two adjacent groups of ridges.
Claim 8
Dependent Claim
24 words
A filter as claimed in any one of claims 1, 3 or 2 where the element values are selected from a Zolotarev function prototype.
Claim 9
Dependent Claim
24 words
A filter as claimed in any one of claims 1, 3 or 2 where the element values are selected from a Chebyshev function prototype.
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) | 1990-06-15 | 1990-12-15 | 1991-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-15 | 1994-12-15 | 1995-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-15 | 1998-12-15 | 1999-06-16 | $7700.00 | Window Closed / Lapsed |