US3909755A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low pass microwave filter
Assignee: United States Department of the Army
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Filing: 1974-07-18
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Granted: 1975-09-30
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Expires: 1994-07-18
Abstract
Abstract A low pass microwave filter comprised of a two conductor transmission line including at least two cascaded tapered sections wherein one of the conductors in each filter section has a tapered surface, preferably linear, and having an electrical length substantially equal to one half the wavelength of the center frequency of operation. Geometrically and performance-wise the subject filter is unsymmetrical with respect to its input and output ports. The filter does not exhibit the usual rapid transition between the pass band and stop band which is a general characteristic of conventional low pass microwave filters utilizing reflective harmonic structures.
Inventors
- 👤 Helmuth M Kaunzinger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:58
CPC Classifications
H; H01; H01P; H01P1/00; H01P1/20; H01P1/207; H01P1/211; H01P1/201
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
181 words
A low pass microwave transmission line filter having input and output end ports and being unsymmetrical about its ports, for inclusion in a transmission line having first and second continuous guiding surfaces, said filter comprising, spaced conductive means providing third and fourth guiding surfaces facing toward each other, the third guiding surface having, at each port of said filter, a configuration to form a continuation of the first guiding surface of the transmission line, the fourth guiding surface having, at each port of said filter, a configuration to form a continuation of the second guiding surface of the transmission line, said third guiding surface being geometrically continuous longitudinally throughout the extent of the filter, the fourth guiding surface including more than one tapered segment, the direction of taper of all segments being the same, each segment having a transition that is essentially perpendicular to the length of the filter, whereby said filter is operable in a frequency band having a center frequency corresponding to a wavelength that is substantially twice the length of each tapered segment measured longitudinally of the filter.
Claim 2
Dependent Claim
181 words
A low pass microwave transmission line filter having input and output end ports and being unsymmetrical about its ports, for inclusion in a transmission line having first and second continuous guiding surfaces, said filter comprising, spaced conductive means providing third and fourth guiding surfaces facing toward each other, the third guiding surface having, at each port of said filter, a configuration to form a continuation of the first guiding surface of the transmission line, the fourth guiding surface having, at each port of said filter, a configuration to form a continuation of the second guiding surface of the transmission line, said third guiding surface being geometrically continuous longitudinally throughout the extent of the filter, the fourth guiding surface including more than one tapered segment, the direction of taper of all segments being the same, each segment having a transition that is essentially perpendicular to the length of the filter, whereby said filter is operable in a frequency band having a center frequency corresponding to a wavelength that is substantially twice the length of each tapered segment measured longitudinally of the filter.
Claim 3
Dependent Claim
16 words
The filter as defined by claim 1 wherein said tapered segments have substantially linear periodic tapers.
Claim 4
Dependent Claim
18 words
The filter as defined by claim 2 wherein said guiding surfaces are on inner and outer coaxial conductors.
Claim 5
Dependent Claim
89 words
The filter as defined by claim 3 wherein said tapered segments are generally frusto-conical in configuration and each segment is terminated by a short cylindrical integral extension at its end of maximum departure relative to the fourth guiding surface, said filter additionally including a dielectric spacer between the inner surface of said outer conductor and said inner conductor at the region of said tapered segments and wherein said integral extensions of said tapered segments contact said spacer for supporting said tapered segments of inner conductor within said outer conductor.
Claim 6
Dependent Claim
33 words
The filter as defined by claim 2 wherein said inner conductor provides said third guiding surface and said outer conductor provides said tapered segments formed along the inner surface of said outer conductor.
Claim 7
Dependent Claim
43 words
The filter as defined by claim 5 wherein said inner conductor is substantially circular in cross section and additionally including a dielectric sleeve around said inner conductor in the region of said tapered segments provided by the inner surface of said outer conductor.
Claim 8
Dependent Claim
64 words
The filter As defined by claim 1 wherein said transmission line is a strip transmission line and wherein said third guiding surface is provided by a metallic substrate acting as a ground plane, and additionally including a dielectric layer on said metallic substrate, and wherein said fourth guiding surface is provided by a strip conductor of substantially constant thickness located on said dielectric layer.
Claim 9
Dependent Claim
61 words
The filter as defined by claim 1 wherein said transmission line is hollow rectangular waveguide with a pair of parallel broadwalls and a pair of parallel sidewalls, said filter being hollow rectangular waveguide having one broadwall that is geometrically continuous and providing said third guiding surface, the other broadwall of said filter having substantially parallel inclined inner surface segments formed therealong.
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) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |