Abstract: A microwave applicator system exposing a material flowing through multiple applicator stages to a different radial heating pattern in each stage for uniform heating. A two-stage applicator system has a pair of back-to-back applicators, each having offset, outwardly jutting walls on opposite sides of a material flow path through a microwave exposure region. The offset, cylindrical juts formed in the wide walls of the generally rectangular waveguide cause hot spots to occur in material flowing through and between the narrow walls of the waveguide at opposite radial positions on a radial line oblique to the longitudinal direction of the waveguide. Uniform product heating can be achieved by directing a material sequentially through these two applicators in opposite directions. A cascaded applicator in which each wide wall has a pair of outward juts offset from each other and from the pair of juts on the other side wall may be used.

Abstract: Microwave apparatus for exposing materials on an elongated member, such as a mandrel, to microwave energy. The apparatus includes a cylindrical microwave exposure chamber (10). Elongated slots (20) spaced about the circumference of the chamber (10) are in communication with openings (50) in the walls of waveguides (28) attached to the exterior (19) of the chamber. Microwave energy fed into the waveguide (28) is coupled into the chamber (10) through the associated openings (50) and slots (20). Bars (54) spaced apart in the direction of wave propagation span the opening (50) in the waveguide for uniform or customized delivery of microwave energy into the chamber (10). A low-profile mode stirrer (38) at the rear end of the chamber further evens out the energy distribution. A front plate (62) seals to the chamber and supports a rotatable mandrel (60) on which material to be exposed to microwave energy in the chamber (10) is wrapped.

Abstract: A microwave applicator system exposing a material flowing through multiple applicator stages to a different radial heating pattern in each stage for uniform heating. A two-stage applicator system has a pair of back-to-back applicators, each having offset, outwardly jutting walls on opposite sides of a material flow path through a microwave exposure region. The offset, cylindrical juts formed in the wide walls of the generally rectangular waveguide cause hot spots to occur in material flowing through and between the narrow walls of the waveguide at opposite radial positions on a radial line oblique to the longitudinal direction of the waveguide. Uniform product heating can be achieved by directing a material sequentially through these two applicators in opposite directions. A cascaded applicator in which each wide wall has a pair of outward juts offset from each other and from the pair of juts on the other side wall may be used.

Abstract: Heating and drying devices including generally rectangular waveguide applicators forming exposure chambers for uniformly heating materials. Material to be heated enters and exits a microwave exposure region of the chamber through entrance and exit ports at opposite ends of the chamber. Various techniques are used to achieve uniform or preferred heating effects.

Abstract: Microwave apparatus for exposing materials on an elongated member, such as a mandrel, to microwave energy. The apparatus includes a cylindrical microwave exposure chamber (10). Elongated slots (20) spaced about the circumference of the chamber (10) are in communication with openings (50) in the walls of waveguides (28) attached to the exterior (19) of the chamber. Microwave energy fed into the waveguide (28) is coupled into the chamber (10) through the associated openings (50) and slots (20). Bars (54) spaced apart in the direction of wave propagation span the opening (50) in the waveguide for uniform or customized delivery of microwave energy into the chamber (10). A low-profile mode stirrer (38) at the rear end of the chamber further evens out the energy distribution. A front plate (62) seals to the chamber and supports a rotatable mandrel (60) on which material to be exposed to microwave energy in the chamber (10) is wrapped.

Abstract: Heating and drying devices including generally rectangular waveguide applicators forming exposure chambers for uniformly heating materials. Material to be heated enters and exits a microwave exposure region of the chamber through entrance and exit ports at opposite ends of the chamber. Various techniques are used to achieve uniform or preferred heating effects.

Abstract: A device for heating a material utilizes a rectangular waveguide with an elongated opening for passing a planar material through the rectangular waveguide. A source creates an electric field between a top surface and a bottom surface of the rectangular waveguide. The electric field is controlled to compensate for attenuation of the electric field. The electric field can be controlled by, for example, using a dielectric slab along the top surface of the rectangular waveguide or a tapered dielectric slab along the top surface of the rectangular waveguide. The electric field can also be controlled by, for example, making the waveguide appear electrically wider at one end. The waveguide can be made to appear electrically wider at one end by, for example, inserting one or more tapered fins. The tapered fins can be adjusted or removed to account for the lossiness of the planar material.