US3757070A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microwave heating apparatus with tuning means
Assignee: Canadian Patents and Development Ltd
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Filing: 1972-06-19
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Granted: 1973-09-04
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Expires: 1992-06-19
Abstract
Abstract In a microwave heating apparatus the tuning means, connecting the microwave source to the microwave heating means in which a material is heated by exposure to microwave energy, comprises a main section of waveguide having first, second and a third branch waveguides each having an adjustable tuning stub in the form of a rotatable vane in a circular extension of each branch waveguide. A group of four sensing probes attached to the main section of waveguide between the source and first branch adjusts the effective electrical lengths of the tuning stubs in the first and second branch waveguides, and a further two sensing probes between the second and third branch waveguides adjust the effective electrical length of the tuning stub in the third branch waveguide.
Inventors
- 👤 Koughnett A Van
- 👤 W Wyslouzil
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 08:05
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/64; H05B6/78; H05B6/66; H05B6/68
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
280 words
In a microwave heating apparatus, comprising a microwave energy source, and a microwave heating means conected thereto for heating a material by exposure to microwave energy from the microwave energy source, a microwave tuning means forming the connection between the microwave energy source to the microwave heating means, the tuning means comprising a main waveguide section connecting the output of the microwave energy source to the input of the microwave heating means, first, second and third branch waveguides connected to the main waveguide section at spaced positions therealong from the microwave energy source, first, second and third adjustable tuning stubs attached to the first, second and third branch waveguides respectively, four signal sensing probes attached to the main waveguide section at spaced positions therealong between the microwave energy source and the first branch waveguide two further sensing probes attached to the main waveguide section as spaced positions therealong between the second and third branch waveguides, four microwave detectors each connected to one of said four sensing probes, two microwave detectors each connected to one of said two further sensing probes, a control circuit connected to said four micowe detectors and to said first and second adjustable tuning stubs to adjust, in response to said four microwave detector outputs, the effective electrical lengths of said first and second adjustable tuning stubs, and a control circuit connected to said two microwave detectors and to said third tuning stub to adjust, in response to the outputs of said two microwave detectors, the effective electrical length of the third tuning stub, whereby the microwave tuning means, in combination with the microwave heating means presents a substantially non-reflecting microwave load to the microwave energy source.
Claim 2
Dependent Claim
280 words
In a microwave heating apparatus, comprising a microwave energy source, and a microwave heating means conected thereto for heating a material by exposure to microwave energy from the microwave energy source, a microwave tuning means forming the connection between the microwave energy source to the microwave heating means, the tuning means comprising a main waveguide section connecting the output of the microwave energy source to the input of the microwave heating means, first, second and third branch waveguides connected to the main waveguide section at spaced positions therealong from the microwave energy source, first, second and third adjustable tuning stubs attached to the first, second and third branch waveguides respectively, four signal sensing probes attached to the main waveguide section at spaced positions therealong between the microwave energy source and the first branch waveguide two further sensing probes attached to the main waveguide section as spaced positions therealong between the second and third branch waveguides, four microwave detectors each connected to one of said four sensing probes, two microwave detectors each connected to one of said two further sensing probes, a control circuit connected to said four micowe detectors and to said first and second adjustable tuning stubs to adjust, in response to said four microwave detector outputs, the effective electrical lengths of said first and second adjustable tuning stubs, and a control circuit connected to said two microwave detectors and to said third tuning stub to adjust, in response to the outputs of said two microwave detectors, the effective electrical length of the third tuning stub, whereby the microwave tuning means, in combination with the microwave heating means presents a substantially non-reflecting microwave load to the microwave energy source.
Claim 3
Dependent Claim
171 words
Tuning means according to claim 1, wherein said first, second and third tuning stubs each comprise a circular cross-section waveguide each forming a butt joint with their respective said first, second and third branch waveguides, said first, second aNd third branch waveguides are rectangular in cross-section, symmetrical inductive irises partially match the resulting discontinuity presented to microwave energy between said first, second and third branch waveguides, said circular cross-section waveguides are each identical comprising two tubular sections joined by a lap joint forming a choke for reflected microwave energy therein, each circular cross-section waveguide contains a metal block of circular cross-section, rotatably mounted coaxially therein, with a diametrically disposed, short circuiting fin, and an annular slot forming a radial waveguide, and driving means, controlled by said control circuits, are coupled to said metal blocks to rotate them to angular adjust the short circuit fins in response to the outputs of said four and said two microwave detectors, thereby adjusting the effective electrical lengths of said first, second and third tuning stubs.
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) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |