The Rubbright Group, Inc.

Whirlpool Corporation

Skandinavisk Torkteknik Ab

Per O Risman

Ulf Nordh

Dan Carlsson

Charles R Buffler

A device and a method for microwave feeding of an oven cavity by means of a coupling slot (,) which is fed by a waveguide. The a-dimension of the waveguide is significantly larger than the effective a-dimension of the slot. The slot comprised a radiating main slot part (,) and slot extensions (,) projecting from it at its respective sides, which extension have a substantially smaller cross-dimension than the b-dimension of the main slot part.

Microwave feeding of an oven cavity

An assembly for applying microwave irradiation to a load having a generally circular cross-section. The applicator supports a dominant TM.sub.120 mode and the load is aligned with a central axis in the applicator, with each aperture of a pair of feed apertures diametrically opposed (for the circular cross sectional case) or located on parallel opposed walls (for the polygonal cross sectional case) with one of the pair of feed apertures positioned at 90 degrees with respect to the other pair about the axis. The applicator may be formed as a cylinder or as a polygonal prism of the type having parallel opposed sides, such as those having a square, hexagonal or octagonal cross-section. Means such as a microwave transparent tube or conveyor provide for positioning of the load in the applicator. In an alternative embodiment, two cavities are used, with one cavity associated with each of the two feed systems, and a means for conveying the load from the first cavity to the second cavity is provided. In one octagonal cross section embodiment, the two feed aperture pairs are located in one cavity.

Tubular microwave applicator

A microwave applicator of microwave reflective material having a closed first end, four side walls and, in a first embodiment, an open second end spaced apart from and facing a ground plate, the ground plate extending in a pair of transverse directions and having a longitudinal direction perpendicular thereto, and in a second embodiment, a closed second end, the applicator forming a cavity containing a desired hybrid mode having a low wave impedance in the longitudinal direction and an absence of an E field component in one of the transverse directions.

Rectangular microwave heating applicator with hybrid modes

A microwave applicator including a generally cylindrical microwave containment chamber, a microwave energy source, and a feed structure connecting the microwave energy source to the containment chamber. The diameter of the containment chamber is designed according to a process that need only take into account supporting a microwave pattern having substantially only two transverse magnetic modes, each with a characteristic guide wavelength, where the guide wavelength of one mode is substantially equal to twice the guide wavelength of the other mode. Additionally, the interior diameter can be sized to minimize the index subscript numbers of the transverse magnetic modes. The feed structure of the applicator includes at least two feed apertures spaced physically apart around the cylindrical axis of the applicator by a physical angle equal to an electrical phase shift angle of the microwaves introduced through the respective apertures, which in a preferred embodiment is 90 degrees.

Cylindrical microwave heating applicator with only two modes

A microwave heating applicator usable in preformed holes in mansonry and the like for heating and dehumidifying areas around the holes is formed from a length of coaxial transmission line. Radiating elements are formed in the outer conductor of the coaxial line for providing an asymmetrical radiation pattern. The radiating elements are provided by forming circumferential axial discontinuities in the outer conductor, each discontinunity having a pair of non-parallel cut edges formed in the outer conductor encircling the line, leaving an asymmetrical open area extending axially between the cut edges. One of the cut edges may describe a plane perpendicular to the coaxial line's z axis while the other cut edge describes a plane which is not perpendicular to the coaxial line z axis. The radiating elements may be provided at intervals along the coaxial line. An end radiating element may be formed having only one edge cut in the outer conductor, the element being bounded by the remote end of the coaxial line with the outer conductor removed therebetween. A flattened radiation pattern may be obtained by orienting adjacent radiating elements with their respective radiating asymmetries angularly rotated 180 degrees relative one another. The interval between radiating elements must be at least on the order of one-half wavelength in the antenna medium of the coaxial line. The applicator may be provided with a microwave-transparent outer protective cover.

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Harryda, Sweden

Per O Risman