Patent US3555232A successfully refreshed from Google Patents.
US3555232A
Expired / Lapsed
US
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Waveguides
Assignee: Canadian Patents and Development Ltd
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Filing: 1968-10-21
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Granted: 1971-01-12
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Expires: 1988-10-21
Abstract
Abstract A rectangular waveguide has two pairs of inwardly projecting ridges. Intensification of the electric field occurs between the ridges of each pair, thus causing an area of relative field rarefaction in a central region of the waveguide between the pairs of ridges. The ridges are tapered longitudinally to vary the ratio of intensification to rarefaction. Workpieces to be heated (dried or cooked or otherwise processed) are passed through the central area to receive controlled quantities of microwave energy, thus improving the uniformity of heating. matchbox can also be used in a slotted waveguide antenna. Variants include use of a region of field intensification for energy extraction instead of a region of field rarefaction, in which case the taper will usually be negative, i.e. will take the form of enlargement. Alternatively, the ridges can be caused to converge to vary the electric field, or a combination of converging and tapering ridges can be used. Alternatively, two spaced areas of field intensification can be used simultaneously, for example to dry the match striking compound on the sides of a matchbox cover.
Inventors
- 👤 William J Bleackley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:39
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/64; H05B6/78; H05B6/782; H01; H01Q; H01Q21/00; H01Q21/0006; H01Q21/0037; H01Q21/0043
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
145 words
An elongated waveguide having an interior cross-sectional shape symmetrical about each of a pair of mutually perpendicular planes intersecting each other to define the longitudinal axis of the waveguide, said waveguide being formed with two pairs of conducting ridges projecting inwardly of the waveguide, said pairs being arranged each on a respective side of a first one of said planes with the respective ridges of each pair having surfaces approaching each other from a pair of walls of the waveguide arranged on opposite sides of the second of said planes, to form regions of electric field intensification between said approaching surfaces upon energization of the waveguide, said pairs being spaced apart from each other to provide a region of electric field rarefaction in the vicinity of said axis; and means for propagating microwave energy along the waveguide in the direction of extent of said ridges.
Claim 2
Dependent Claim
145 words
An elongated waveguide having an interior cross-sectional shape symmetrical about each of a pair of mutually perpendicular planes intersecting each other to define the longitudinal axis of the waveguide, said waveguide being formed with two pairs of conducting ridges projecting inwardly of the waveguide, said pairs being arranged each on a respective side of a first one of said planes with the respective ridges of each pair having surfaces approaching each other from a pair of walls of the waveguide arranged on opposite sides of the second of said planes, to form regions of electric field intensification between said approaching surfaces upon energization of the waveguide, said pairs being spaced apart from each other to provide a region of electric field rarefaction in the vicinity of said axis; and means for propagating microwave energy along the waveguide in the direction of extent of said ridges.
Claim 3
Dependent Claim
29 words
A waveguide according to claim 1, for use as a microwave heater, including means for conveying a workpiece along the waveguide in the direction of extent of said ridges.
Claim 4
Dependent Claim
23 words
A waveguide according to claim 2, wherein said conveying means comprise means for conveying the workpiece along said region of electric field rarefaction.
Claim 5
Dependent Claim
47 words
A waveguide according to claim 1 for use as a microwave heater and including means for conveying a generally sheetlike workpiece in a direction transverse to the longitudinal extent of the waveguide and substantially along said first plane to pass through said region of electric field rarefaction.
Claim 6
Dependent Claim
46 words
A waveguide according to claim 1, wherein said ridges are tapered in the longitudinal direction of the waveguide to vary the spacing between said approaching surfaces and hence the ratio between the degree of said intensification and the degree of said rarefaction of the electric field.
Claim 7
Dependent Claim
33 words
A waveguide according to claim 5 for use as a microwave heater and including means for conveying a workpiece in the longitudinal direction of the waveguide along said region of electric field rarefaction.
Claim 8
Dependent Claim
47 words
A waveguide according to claim 5 for use as a microwave heater and including means for conveying a generally sheetlike workpiece in a direction transverse to the longitudinal extend of the waveguide and substantially along said first plane to pass through said region oF electric field rarefaction.
Claim 9
Dependent Claim
54 words
A waveguide according to claim 5 for use as a slotted antenna and including a series of radiating slots formed in one of said pair of walls, said series of slots extending in the longitudinal direction of the waveguide with alternate slots offset to respective sides of said first plane by substantially equal amounts.
Claim 10
Dependent Claim
69 words
A waveguide according to claim 8, wherein each of said ridges is tapered from a maximum degree of projection at one end of the waveguide down to a minimum degree of projection at a location intermediate the ends of the waveguide and is tapered out again to a degree of projection at the other end of the waveguide intermediate in degree between said maximum and minimum degrees of projection.
Claim 11
Dependent Claim
44 words
A waveguide according to claim 1, for use as a microwave heater and including means for conveying a workpiece in the longitudinal direction of the waveguide with a portion of said workpiece to be heated located in a said region of electric field intensification.
Claim 12
Dependent Claim
83 words
A waveguide according to claim 10, including means defining a direction of microwave energy flow along the waveguide, wherein said ridges are tapered in the longitudinal direction of the waveguide from a maximum degree of projection at an energy downstream location in the waveguide to a minimum degree of projection at an energy upstream location in the waveguide to vary the ratio between the field intensification and rarefaction to compensate in heating effect on the workpiece for attenuation in the energy downstream direction.
Claim 13
Dependent Claim
64 words
A waveguide according to claim 6, wherein said ridges are tapered from a maximum degree of projection at an energy upstream location in the waveguide to a minimum degree of projection at an energy downstream location in the waveguide to vary the ratio between the field intensification and rarefaction to compensate in heating effect on the workpiece for attenuation in the energy downstream direction.
Claim 14
Dependent Claim
47 words
A waveguide according to claim 1, including a mass of dielectric material provided in the waveguide at a location on the side of each pair of ridges remote from said axis, said material comprising means for further rarefying the electric field in the vicinity of said axis.
Claim 15
Dependent Claim
35 words
A waveguide according to claim 13, wherein each said mass of dielectric material is tapered in the longitudinal direction of the waveguide to vary the effect thereof on such further rarefaction of the electric field.
Claim 16
Dependent Claim
57 words
A waveguide according to claim 1, laterally extended to include at least one further pair of similar projecting ridges arranged to form a further region of electric field intensification between approaching surfaces thereof, each such further pair of ridges being spaced from another of said pairs of ridges to provide a further region of electric field rarefaction.
Claim 17
Dependent Claim
48 words
A waveguide according to claim 15, wherein at a selected location in the longitudinal direction of the waveguide the degree of closeness of the pairs of approaching ridge surfaces is greater nearer the lateral edges of the waveguide and becomes progressively less towards the center of the waveguide.
Claim 18
Dependent Claim
86 words
In a microwave heater, an elongated waveguide having two inwardly projecting, elongated, conducting ridge structures, each extending longitudinally along said waveguide, means for propagating microwave energy along the waveguide in the direction of extent of said ridge structures, each of said structures forming an area of electric field intensification upon energization of the waveguide, said ridge structures being spaced apart from each other to provide between them a region of electric field rarefaction, and means for conveying a workpiece through said region of electric field rarefaction.
Claim 19
Dependent Claim
86 words
In a microwave heater, an elongated waveguide having two inwardly projecting, elongated, conducting ridge structures, each extending longitudinally along said waveguide, means for propagating microwave energy along the waveguide in the direction of extent of said ridge structures, each of said structures forming an area of electric field intensification upon energization of the waveguide, said ridge structures being spaced apart from each other to provide between them a region of electric field rarefaction, and means for conveying a workpiece through said region of electric field rarefaction.
Claim 20
Dependent Claim
34 words
The structure of claim 17, wherein said ridge structures are tapered in the longitudinal direction of the waveguide to vary the ratio between the degree of said intensification and the degree of said rarefaction.
Claim 21
Dependent Claim
179 words
An elongated waveguide for use as a microwave heater and havIng a cross section including an internal conducting ridge structure comprising at least one ridge projecting from one wall of the wave guide towards an opposite wall of the waveguide and to a location spaced from said opposite wall to form opposed surfaces defining at least one region in which, upon energization of the waveguide, the electric field is more intensified than in at least one other region of the waveguide where the electric field is more rarefied, and including means defining a direction of microwave energy flow along the waveguide, and means for conveying a workpiece in the longitudinal direction of the waveguide along said region of field intensification, said ridge structure being tapered in the longitudinal direction of the waveguide from a maximum degree of projection at an energy downstream location to a minimum degree of projection at an energy upstream location to vary the ratio between such field intensification and rarefaction to compensate in heating effect on the workpiece for attenuation in the energy downstream direction.
Claim 22
Dependent Claim
179 words
An elongated waveguide for use as a microwave heater and havIng a cross section including an internal conducting ridge structure comprising at least one ridge projecting from one wall of the wave guide towards an opposite wall of the waveguide and to a location spaced from said opposite wall to form opposed surfaces defining at least one region in which, upon energization of the waveguide, the electric field is more intensified than in at least one other region of the waveguide where the electric field is more rarefied, and including means defining a direction of microwave energy flow along the waveguide, and means for conveying a workpiece in the longitudinal direction of the waveguide along said region of field intensification, said ridge structure being tapered in the longitudinal direction of the waveguide from a maximum degree of projection at an energy downstream location to a minimum degree of projection at an energy upstream location to vary the ratio between such field intensification and rarefaction to compensate in heating effect on the workpiece for attenuation in the energy downstream direction.
Claim 23
Dependent Claim
79 words
A waveguide according to claim 19, wherein said ridge structure comprises a pair of ridges projecting from said wall of the waveguide towards said opposite wall, said pair of ridges lying closely adjacent each other to form a substantially uninterrupted region of field intensification between such ridges and said opposite wall, and a slot in said opposite wall for receiving a flat workpiece projecting therethrough to locate a portion of said workpiece to be heated in said last-mentioned region.
Claim 24
Dependent Claim
136 words
An elongated waveguide for use as a microwave heater and having a cross section including an internal conducting ridge structure comprising at least two ridges projecting from one wall of the waveguide towards an opposite wall of the waveguide and each to a location spaced from said opposite wall to form opposed surfaces defining a region of electric field intensification between said opposed surfaces upon energization of the waveguide, said ridges converging in the longitudinal direction of the waveguide between a first condition in which said ridges are spaced apart from each other to provide a region of electric field rarefaction between them and a second condition in which said ridges lie closely adjacent each other with their respective said regions of electric field intensification merging to form a substantially uninterrupted combined region of field intensification.
Claim 25
Dependent Claim
136 words
An elongated waveguide for use as a microwave heater and having a cross section including an internal conducting ridge structure comprising at least two ridges projecting from one wall of the waveguide towards an opposite wall of the waveguide and each to a location spaced from said opposite wall to form opposed surfaces defining a region of electric field intensification between said opposed surfaces upon energization of the waveguide, said ridges converging in the longitudinal direction of the waveguide between a first condition in which said ridges are spaced apart from each other to provide a region of electric field rarefaction between them and a second condition in which said ridges lie closely adjacent each other with their respective said regions of electric field intensification merging to form a substantially uninterrupted combined region of field intensification.
Claim 26
Dependent Claim
65 words
A waveguide according to claim 21, including means defining a direction of microwave energy flow along the waveguide, said first condition of the ridges being upstream of said second condition in relation to said direction of energy flow, and including means for conveying a workpiece in the longitudinal direction of the waveguide between said region of field rarefaction and said combined region of field intensification.
Claim 27
Dependent Claim
61 words
The structure of claim 18, said taper being from a maximum degree of projection and hence a maximum value of said ratio at an energy upstream location to a minimum degree of projection and hence a minimum value of said ratio at an energy downstream location to compensate in heating effect on the workpiece for attenuation in the energy downstream direction.
Claim 28
Dependent Claim
120 words
An elongated waveguide for use as a slotted antenna and including a series of radiating slots formed in one wall thereof, said series of slots extending in the longitudinal direction of the waveguide with alternate slots offset to respective sides of a central electric plane of the waveguide, said waveguide having an inwardly projecting conducting ridge structure for forming at least one region of electric field intensification and at least one region of electric field rarefaction upon energization of the waveguide, said ridge structure being tapered in the longitudinal direction of the waveguide to vary the ratio between the degree of said intensification and the degree of said rarefaction to control the level of energy loss from the respective slots.
Claim 29
Dependent Claim
120 words
An elongated waveguide for use as a slotted antenna and including a series of radiating slots formed in one wall thereof, said series of slots extending in the longitudinal direction of the waveguide with alternate slots offset to respective sides of a central electric plane of the waveguide, said waveguide having an inwardly projecting conducting ridge structure for forming at least one region of electric field intensification and at least one region of electric field rarefaction upon energization of the waveguide, said ridge structure being tapered in the longitudinal direction of the waveguide to vary the ratio between the degree of said intensification and the degree of said rarefaction to control the level of energy loss from the respective slots.
Claim 30
Dependent Claim
102 words
A waveguide accOrding to claim 22, wherein said slots are offset by substantially equal amounts to respective sides of said central plane, and wherein said ridge structure is tapered from a maximum degree of projection at one end of the waveguide down to a minimum degree of projection at a location intermediate the ends of the waveguide and is tapered out again to a degree of projection at the other end of the waveguide intermediate in degree between said maximum and minimum degrees of projection to enable said waveguide to radiate a symmetrical energy lobe while compensating for attenuation along the waveguide.
Claim 31
Dependent Claim
82 words
An elongated waveguide for use as a microwave heater and having a cross section including an internal conducting ridge structure comprising at least one ridge projecting from one wall of the waveguide towards an opposite wall of the waveguide to form opposed surfaces defining a region of electric field intensification between said surfaces upon energization of the waveguide, said ridge structure further constituting means for supporting workpieces for travel in the longitudinal direction of the waveguide along said region of field intensification.
Claim 32
Dependent Claim
82 words
An elongated waveguide for use as a microwave heater and having a cross section including an internal conducting ridge structure comprising at least one ridge projecting from one wall of the waveguide towards an opposite wall of the waveguide to form opposed surfaces defining a region of electric field intensification between said surfaces upon energization of the waveguide, said ridge structure further constituting means for supporting workpieces for travel in the longitudinal direction of the waveguide along said region of field intensification.
Claim 33
Dependent Claim
114 words
A waveguide according to claim 26, wherein said ridge structure comprises two pairs of ridges arranged with said pairs each on a respective side of a first longitudinal plane, with the respective ridges of each pair having surfaces approaching each other from a pair of walls of the waveguide arranged on opposite sides of a second longitudinal plane extending perpendicularly to said first plane to form regions of electric field intensification between said approaching surfaces upon energization of the waveguide, said surfaces being formed as rail means for supporting workpieces for travel in the longitudinal direction of the waveguide with portions of said workpieces to be heated located in said regions of field intensification.
Claim 34
Dependent Claim
76 words
The structure according to claim 32, wherein said energy is removed as heat by a workpiece travelling in the longitudinal direction of the waveguide in a said region of field rarefaction, said modification of the ridge structure being such as to reduce the ratio between field intensification and field rarefaction in the energy downstream direction to cause the level of heating of the workpiece to be substantially uniform along at least a portion of the waveguide.
Claim 35
Dependent Claim
76 words
The structure according to claim 32, wherein said energy is removed as heat by a workpiece travelling in the longitudinal direction of the waveguide in a said region of field intensification, said modification of the ridge structure being such as to increase the ratio between field intensification and field rarefaction in the energy downstream direction to cause the level of heating of the workpiece to be substantially uniform along at least a portion of the waveguide.
Claim 36
Dependent Claim
75 words
The structure according to claim 32, wherein said energy is removed as heat by a sheetlike workpiece travelling transversely of the longitudinal direction of the waveguide essentially through a said region of field rarefaction, said modification of the ridge structure being such as to reduce the ratio between field intensification and field rarefaction in the energy downstream direction to cause the level of heating of the workpiece to be substantially uniform across the width thereof.
Claim 37
Dependent Claim
34 words
The structure according to claim 32, wherein said energy is removed by slots formed in a wall of the waveguide and arranged substantially equally offset alternately from a central electrical plane of the waveguide.
Claim 38
Dependent Claim
146 words
In an elongated waveguide having means for supplying microwave energy at an input end thereof for propagation therealong, means for controlling the level of removal of said microwave energy at various locations along the waveguide, said control means comprising: a. a conducting ridge structure extending along the waveguide from said input end in the direction of propagation of microwave energy therealong and projecting inwardly of the cross section of tHe waveguide for distorting the electric field to provide at least one region of field intensification and at least one region of field rarefaction; b. means for removing microwave energy from the waveguide along the length thereof from one of said regions; and c. means modifying said ridge structure longitudinally of the waveguide to vary the degree of said distortion to compensate for attenuation along the waveguide and control the level of energy removal along the waveguide.
Claim 39
Dependent Claim
146 words
In an elongated waveguide having means for supplying microwave energy at an input end thereof for propagation therealong, means for controlling the level of removal of said microwave energy at various locations along the waveguide, said control means comprising: a. a conducting ridge structure extending along the waveguide from said input end in the direction of propagation of microwave energy therealong and projecting inwardly of the cross section of tHe waveguide for distorting the electric field to provide at least one region of field intensification and at least one region of field rarefaction; b. means for removing microwave energy from the waveguide along the length thereof from one of said regions; and c. means modifying said ridge structure longitudinally of the waveguide to vary the degree of said distortion to compensate for attenuation along the waveguide and control the level of energy removal along the waveguide.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-01-11 | 1974-07-13 | 1975-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-11 | 1978-07-13 | 1979-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-11 | 1982-07-13 | 1983-01-12 | $7700.00 | Window Closed / Lapsed |