US3758737A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Waveguide filter for microwave heating apparatus
Assignee: Goodman Co LP
•
Filing: 1972-06-13
•
Granted: 1973-09-11
•
Expires: 1992-06-13
Abstract
Abstract A low pass filter is provided for rectangular waveguide of the type employed for launching electromagnetic energy in microwave ovens. The filter substantially rejects the transmission of harmonic frequencies of the fundamental generator operating frequency as well as adjacent energy oscillation modes. The structure described has a corrugated configuration with ribs defining alternate cavities and constrictions have cutoff frequency characteristics. Uniform and nonuniform spacing as well as dissimilar sections are discussed. The structure is electrically isolated from the broad waveguide walls to define two propagation paths for the electromagnetic energy. Lightweight conductive materials are suggested. The interrelationships of the alternating rib members provide a series of open and short circuit admittances which are analyzed to determine the desired electrical cutoff frequencies. Identical rib structure is defined on opposing sides of a reference plane extending along the longitudinal axis of the waveguide. Transforming means are utilized for impedance matching.
Inventors
- 👤 R Ironfield
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:31
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/64; H05B6/72; H05B6/725; H01; H01P; H01P1/00; H01P1/16; H01P1/20; H01P1/207; H01P1/211; H01P1/212; H05B6/70; H05B6/707
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
79 words
In combination: an enclosure; means for generating electromagnetic energy having at least a predetermined operating frequency; means for launching said energy within said enclosure; and low pass filter means comprising a body member having alternately spaced rib members mounted in said launching means; said rib members and alternate spaces defining an inductance and capacitance in series along said launching means to provide a predetermined propagation characteristic to substantially prevent transmission of energy at harmonic frequencies of said operating frequency.
Claim 2
Dependent Claim
79 words
In combination: an enclosure; means for generating electromagnetic energy having at least a predetermined operating frequency; means for launching said energy within said enclosure; and low pass filter means comprising a body member having alternately spaced rib members mounted in said launching means; said rib members and alternate spaces defining an inductance and capacitance in series along said launching means to provide a predetermined propagation characteristic to substantially prevent transmission of energy at harmonic frequencies of said operating frequency.
Claim 3
Dependent Claim
13 words
The combination according to claim 1 wherein said rib members are spaced uniformly.
Claim 4
Dependent Claim
13 words
The combination according to claim 1 wherein said rib members are spaced nonuniformly.
Claim 5
Dependent Claim
25 words
The combination according to claim 1 wherein said filter means comprise a body member having spaced rib members extending symmetrically from a predetermined reference plane.
Claim 6
Dependent Claim
87 words
Heating apparatus comprising: an enclosure defined by conductive walls; an electromagnetic energy generator having a fundamental operating frequency characteristic; rectangular waveguide having broad and narrow walls for coupling said energy from said generator to said enclosure; low pass filter means comprising a body member having alternately spaced rib members mounted in said waveguide; said rib members and alternate spaces defining an inductance and capacitance in series along said waveguide to provide a propagation characteristic to substantially prevent transmission of energy at harmonic frequencies of said operating frequency.
Claim 7
Dependent Claim
87 words
Heating apparatus comprising: an enclosure defined by conductive walls; an electromagnetic energy generator having a fundamental operating frequency characteristic; rectangular waveguide having broad and narrow walls for coupling said energy from said generator to said enclosure; low pass filter means comprising a body member having alternately spaced rib members mounted in said waveguide; said rib members and alternate spaces defining an inductance and capacitance in series along said waveguide to provide a propagation characteristic to substantially prevent transmission of energy at harmonic frequencies of said operating frequency.
Claim 8
Dependent Claim
21 words
The apparatus according to claim 6 wherein said rib members extending transversely to the direction of energy propagating along said waveguide.
Claim 9
Dependent Claim
26 words
The apparatus according to claim 5 wherein said rib members extend parallel to the broad waveguide walls and are spaced therefrom to define a propagation path.
Claim 10
Dependent Claim
17 words
The apparatus according to claim 6 wherein said body member is supported by said narrow waveguide walls.
Claim 11
Dependent Claim
23 words
The apparatus according to claim 6 wherein said filter means comprise a body member having spaced rib members symmetrically disposed from opposite sides.
Claim 12
Dependent Claim
30 words
The apparatus according to claim 6 and means for matching the impedance electrical characteristics of said filter means and said waveguide means disposed at the ends of said body member.
Claim 13
Dependent Claim
31 words
The apparatus according to claim 5 wherein the outer extremities of said rib members are spaced from opposing broad walls to define parallel energy propagation paths having substantially identical transmission characteristics.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-10 | 1977-03-12 | 1977-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-10 | 1981-03-12 | 1981-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-10 | 1985-03-12 | 1985-09-11 | $7700.00 | Window Closed / Lapsed |