Abstract: A defrost vessel for a microwave oven includes a body having a certain space therein for receiving a refrigerating load, and an antenna connected to the body for oscillating a microwave into the space of the body. When microwave is supplied into a cavity of the microwave oven, the microwave is oscillated into the space of the body by the antenna and thus the microwave is deeply penetrated up to inside of the refrigerating load. Also, the microwave is secondly emitted into the space of the body from an edge of the slot, thereby completely defrosting the refrigerating load.

Abstract: A remote plasma source employs a helical coil slow wave structure to couple microwave energy to a flowing gas to produce plasma for downstream substrate processing, such as photoresist stripping, ashing, or etching. The system also includes cooling structures for removing excess heat from the plasma source components.

Abstract: The invention relates to a microwave mixer/dryer/reactor for industrial use. The inventive machine has a three-fold purpose, namely to: a) mix solid products with solids, solids with liquids and solids with very viscous fluids; b) dry aforementioned products; and c) initiate reaction between said products by means of suitable microwave discharge from a generator which is specially connected to the shaft of the machine. Said machine can be used to perform one or two of said functions or all the functions together.

Abstract: A microwave water heating system includes a metal casing having an outer wall defining an interior casing chamber. An inner housing is positioned within the casing and includes an outer wall displaced from the casing outer wall to form an insulating vacuum space. The inner housing includes an inlet port connected to an upstream water source and an outlet port connected to a downstream conduit. The casing and inner housing include generally spherical configurations. The inner housing is configured to induce a vortex of a water stream flowing between inlet and outlet ports. At least one magnetron is mounted to the casing for transmitting microwaves into the inner housing for heating the water stream at the vortex. A float valve in the inner housing allows the water stream to flow and be heated upon demand as the valve operates according to upstream and downstream pressure differentials.

Abstract: A magnetron includes semi-circularly shaped electric field adjusting grooves provided on surfaces of outer ends of vanes brought into contact with an inner surface of a positive polar body to make distribution of an electric field uniform on the surfaces of the outer ends of the vanes. Accordingly, the electric field becomes uniform by the electric field adjusting grooves provided on the surfaces of the outer ends of the vanes, so that generation of undesirable harmonics is suppressed.

Abstract: A microwave energy emitter (108) is positioned in a microwave transparent chamber (123) within a fluid holding vessel (106) of a microwave containment vessel (122). The fluid holding vessel (106) may be transparent to microwave energy and is further provided with a microwave reflective component outward, on, or beyond an exterior surface (121) of the wall of the fluid holding vessel (106). The microwave reflective component reflects microwaves back into the fluid holding vessel (106). The fluid holding vessel (106) encloses a material that absorbs microwave energy. An inlet path (116) and outlet path (112) is provided for material to flow in and out of the holding vessel upon predetermined conditions. Heated material can be condensed via a condenser (124) into a collection vessel (120). A controller (126) is provided to send control signals to a switching device (100) for controlling the material flow and receiving sensing signals for decision generation.

Abstract: A cooking device includes a first waveguide portion to make a microwave emitted into a heating chamber propagate radially in the directions almost parallel with the bottom face of the heating chamber and to guide the microwave propagated in the almost parallel directions into the heating chamber, and a second waveguide portion to make the microwave guided into the heating chamber by the first waveguide portion further propagate radially in directions almost parallel with the bottom face and to guide the propagated microwave into the heating chamber.

Abstract: A microwave delivery system for a cooking appliance includes a toroidal waveguide, a launching zone and a waveguide cover. The launching zone includes opposing top, bottom and side walls that form a pathway for a microwave energy field to travel from a magnetron through the waveguide and into a cooking chamber. In accordance with one aspect of the overall invention, the bottom wall of the launching zone is aligned with a bottom surface of the waveguide to establish a direct conducting surface for the microwave energy field. The waveguide cover shields a hollow interior portion of the waveguide from cooking byproducts generated in the cooking chamber during a cooking process. The waveguide cover is preferably constituted by a metallic conductor having a finish that enhances the microwave energy field distribution in the cooking chamber.

Abstract: In order to reduce reflected waves and improve heating matching, a microwave heating apparatus is equipped with at least one cone-shaped, bell-shaped, pyramid-shaped or similarly shaped waveguide, a reflector apparatus provided inside the waveguide, and a reflection diffusion apparatus provided inside the oven.

Abstract: A microwave oven and a method for heating a load which is placed therein. According to the invention a predetermined mode in the cavity of a microwave oven is fed by means of an associated feeding port which is arranged to feed essentially the intended mode only, the feeding of a mode other than the intended, predetermined mode being essentially prevented.

Abstract: A microwave oven includes a motor for a stirrer and a motor mounting unit. The motor is provided at an outer circumferential surface thereof with a first flange having a hole. The motor mounting unit is provided on an outer surface of a wave guide, and includes a seat, a mounting piece provided at an edge of the seat and having a hole, and a stopper. The stopper is upwardly projected from a first piece provided on the seat adjacent to the mounting piece, to delimit a mounted position of the motor. The motor mounting unit also includes a guide piece upwardly projected from a second piece provided at an edge of the seat. A slot is longitudinally formed along the guide piece. The motor has a second flange at a position opposite to the first flange to be fitted into and guided along the slot.

Abstract: This invention provides a heating and cooking apparatus in which foods can be accommodated in a heating chamber with good maneuverability and an appropriate finish can be obtained. A temperature detector detects infrared radiation through an opening provided on a wall surface opposed to an opening part for taking in and out foods of a heating chamber. The temperature detector detects the temperature of a plurality of parts on a sealing having the substantially same electric wave penetrability as that of the bottom surface of the heating chamber. Accordingly, even when two foods are arranged right and left irrespective of the size of the foods, the temperature of both the foods can be detected. Then, the user does not needs to extend a hand to the interior of the heating chamber and arrange the foods in front and back positions.

Abstract: An apparatus for the heating of pressed stock in the manufacture of boards of material or in the manufacture of veneer panels. The apparatus includes a microwave preheating device having rod antennae disposed in series, reflective shields, and a heating cell configured as a continuous oven in which the introduction of microwaves into the pressed stock takes place via the rod antennae. The rod antennae are attached to lie horizontally and transversely to the direction of production above, below, or above and below the pressed stock within the heating cell. The reflective surfaces are assigned to the rod antennae on the opposite sides of the pressed stock.

Abstract: A microwave oven has a heating chamber formed inside a body frame. A radiation antenna is provided below the heating chamber. The radiation antenna is structured in such a way that a member housed in an antenna drive box appropriately operates to change the distance between a bottom surface of the body frame and the radiation antenna. Microwaves generated by a magnetron are supplied through a waveguide and the radiation antenna into the heating chamber. When the level at which the radiation antenna is positioned is changed, the way to supply microwaves from the radiation antenna into the heating chamber is accordingly changed. Specifically, microwaves are locally supplied into the heating chamber or supplied uniformly into the whole of the heating chamber.

Abstract: An elliptical exposure chamber has an extended focal region. A plurality of cylindrical reactors (25) form the extended focal region. Reducing the size of the opening (58) to each reactor (25) reduces the amount of energy reflected and increases the overall heating. In order to efficiently deliver the electromagnetic energy to the reduced opening (58), a tapered waveguide (55) has a concave end (56). A power splitter (42) divides power from a central waveguide (52) to the plurality of reactors (25). The power that is delivered to each reactor (25) can be adjusted by adjusting the impedance of each reactor (25), the width of each reactor (25) or the width of the opening (58) to each reactor (25). The width of the opening (58) to each reactor (25) can be controlled by a movable metal plate (44). A dielectric wheel can be used to shift hot spots along the focal region.

Abstract: A microwave delivery system for a cooking appliance having a cooking chamber includes a toroidal-shaped waveguide, a magnetron, a tubular feed member interconnecting the magnetron with the toroidal-shaped wave guide and a field flux generator positioned about the tubular feed member. The flux field generator shifts a microwave energy field produced by the magnetron in the tubular feed member. The shifted microwave field focuses high energy standing waves that are directed into the toroidal-shaped wave guide and, ultimately, the cooking chamber. The field flux generator produces either magnetic or electrical fields and is driven by a pulsed DC current, a rectified AC current or a pure AC signal energy source.

Abstract: A magnetron includes a filament to irradiate thermoelectrons, a plurality of anodic vanes arranged around the filament in radial directions, and an antenna connected to at least one of the anodic vanes. The vane connected to the antenna is provided with an antenna holding part. The antenna holding part outwardly extends from an upper edge of the vane by a predetermined length to connect the antenna to the vane.

Abstract: A method and apparatus for adaptively maintaining the power-frequency spectrum in a reverberation chamber. The invention is thus capable of maintaining a relatively constant power-frequency spectrum in the chamber even when a device under examination is placed into the chamber which exhibits selective frequency absorption and or directional frequency absorption. The object disposed within the chamber need not necessarily be a device under examination. Rather, the present invention can also adaptively maintain a relatively constant power-frequency spectrum when heating any material disposed within a electromagnetic wave chamber.

Abstract: An instrument is disclosed for microwave-assisted chemical processes that avoids tuning discrepancies that otherwise result based upon the materials being heated. The instrument includes a source of microwave radiation, a waveguide in communication with the source, with at least a portion of the waveguide forming a cylindrical arc, a cylindrical cavity immediately surrounded by the cylindrical arc portions of the waveguide, and at least three slotted openings in the circumference of the circular waveguide that provide microwave communication between the waveguide and the cavity.

Abstract: A microwave polymerization system for dentistry utilizes specifically controlled microwave energy to cure polymer materials so as to produce dental prosthetics, such as dentures, bridges and crowns, that are made in an extra-oral setting such as a dental laboratory or dental office, and to create dental composites for fillings and veneers that are used in an intra-oral setting directly in the patient's mouth. Unlike the microwave energy delivered by commercial microwave ovens, the system utilizes metered and controlled microwave energy that is preferably continuous and voltage controlled, and regulates the application of this microwave energy by use of various feedback and control mechanisms. The metered and controlled microwave energy enables a higher degree of conversion of monomers into polymer chains in the polymerization process, thereby enhancing the physical and biocompatibility characteristics of both dental prosthetics and dental composites made from polymers.

Abstract: An instrument is disclosed for microwave-assisted chemical processes that avoids tuning discrepancies that otherwise result based upon the materials being heated. The instrument includes a source of microwave radiation, a waveguide in communication with the source, with at least a portion of the waveguide forming a cylindrical arc, a cylindrical cavity immediately surrounded by the cylindrical arc portions of the waveguide, and at least three slotted openings in the circumference of the circular waveguide that provide microwave communication between the waveguide and the cavity.

Abstract: In order to reduce reflected waves and improve heating matching, a microwave heating apparatus is equipped with at least one cone-shaped, bell-shaped, pyramid-shaped or similarly shaped waveguide, a reflector apparatus provided inside the waveguide, and a reflection diffusion apparatus provided inside the oven.

Abstract: A microwave delivery system for a cooking appliance includes a toroidal waveguide and a launching zone. The launching zone has an interior metallic surface into which a microwave energy field is introduced. The microwave energy field couples with the interior metallic surface of the launching zone thus increasing the efficiency of the energy field as it enters the waveguide. Additionally, a tuning form section is provided in the waveguide which further enhances the microwave energy field, thereby creating a maximum energy node around the inside and outside of the waveguide. Insulation is provided both in the interior of the waveguide and in a central, exterior depression defined by the waveguide.

Abstract: A microwave delivery system for a cooking appliance includes a toroidal waveguide having a ring diameter twice that of the wavelength of the microwaves produced by a magnetron, and a cross-sectional diameter equal to one-half of the produced microwaves. The waveguide includes a plurality of cavity excitation ports through which the microwaves enter a cooking cavity. The delivery system further includes a rotating stirrer positioned within the waveguide. The stirrer includes a plurality of openings which become aligned with the cavity excitation ports when the stirrer is rotated to create a uniform, high energy pattern of microwave energy to enter the cooking cavity. Finally, the waveguide includes a plurality of openings along spaced portions thereof to allow a flow of air through the waveguide.

Abstract: A microwave cooking appliance includes a sheathed resistive electric heating element including an outer portion, an inner portion and a cross-over portion electrically interconnecting the outer and inner portions. The heating element is arranged in a cooking chamber of the microwave cooking appliance in a manner which effects an impedance characteristic of the cooking chamber. The cross-over portion is arranged such that the heating element acts like an RF antenna moving a microwave energy field to portions of the cooking chamber in which low electric fields occur. In this manner, the broil element helps increase the operational efficiency of the cooking applaince by minimizing any hot and cold spots within the cooking chamber.

Abstract: An opening is formed in a right side of a heating chamber. The opening is covered by a protection cover. A waveguide is connected to the opening. A magnetron is connected to the waveguide. The magnetron has a magnetron antenna. An emission antenna is arranged around the magnetron antenna. A rotating plate is mounted to the protection cover. A plurality of diffusion antennas are mounted to the rotating plate. The diffusion antennas are arranged from the waveguide to the heating chamber.

Abstract: A microwave oven determines an appropriate time to stop heating even if multiple food items are placed in the heating chamber. After any position on the bottom surface of the microwave oven reaches 75 deg C., a search is made for any other position having a temperature of at least 70 deg C. If such a position is detected, heating is concentrated on that position until it reaches 75 deg C. When all food-containing positions in the microwave oven have reached a temperature of at least 75 deg C., the heating operation performed by the magnetron is stopped.

Abstract: A microwave oven having a wave distributing device. A motor-operated rotor is installed inside a cooking cavity to distribute high-frequency electromagnetic waves (“microwaves”) generated by the oscillation of a magnetron. The wave distributing device includes a rotation trace limiter which limits a rotation trace of the rotor within a predetermined range. The rotation trace limiter includes stoppers which limit the rotation of the rotor, or a cam mechanism unit which changes a movement of a motor shaft connecting the rotor to the motor. Accordingly, an optimum energy efficiency is achieved, thereby saving energy required during an operation of the microwave oven under a standard load. In addition, the amount of the microwaves reflected back to the magnetron during an operation under a no-load or a light load is reduced. Therefore, life expectancy of the magnetron and the overall operational reliability of the microwave oven are improved.

Abstract: A microwave oven heats all food in an appropriate manner even if food items are simultaneously placed at multiple locations in a heating chamber. An auxiliary antenna is periodically stopped at an orientation corresponding to a position where a lowest temperature was detected at the start of the heating operation. Between stopped periods, the auxiliary antenna is rotated for a period to apply heat evenly to all food in the oven. If multiple low-temperature points are detected, the central position of these multiple low-temperature points is used for applying concentrated heat.

Abstract: A seal for an opening defined by a sidewall portion of the pressurizable tank. The tank contains desiccant for drying gases which pass through the desiccant. An elongate antenna extends from an interior portion to an exterior portion of the tank and is used for carrying microwave energy to the desiccant for regeneration of the desiccant. The seal has an insulator with an interior surface for receiving engagement with the antenna at the opening of the tank. In one embodiment, the interior surface of the insulator is tapered such that a distance between opposing portions of the insulator reduces as the insulator extends in a direction through the opening toward the exterior of the tank. The antenna has a cross sectional dimension which reduces in size as the antenna extends in the direction through the opening toward the exterior of the tank.

Abstract: A microwave oven heats all food in an appropriate manner even if food items are simultaneously placed at multiple locations in a heating chamber. An auxiliary antenna is periodically stopped at an orientation corresponding to a position where a lowest temperature was detected at the start of the heating operation. Between stopped periods, the auxiliary antenna is rotated for a period to apply heat evenly to all food in the oven. If multiple low-temperature points are detected, the central position of these multiple low-temperature points is used for applying concentrated heat.

Abstract: A continuous flow type heating apparatus using microwave, which can continuously supply hot water with practically usable flow amount and temperature. An open part is formed on a top face of a horizontally prolonged empty box 10 to become an emitting port of the microwave. The empty box 10 is divided into two by a vertical partition except for the upper and lower part of the emitting port. One side of the space is horizontally divided into three by two of an upper and a lower partitions 12, 13 on which slits 12a, 13a are set at a desired interval. The space formed on the partition 12 becomes a first irradiation part 4. The space formed under the partition 13 and connected in lower part to the space on another side becomes a second irradiation part 5. A water supply pipe 2 is disposed at the center of the space formed between the partitions 12 and 13. The microwave from a microwave oscillator 6 is irradiated from the emitting port into the empty box 10.

Abstract: This invention relates to a dielectric heating device. More particularly, it relates to a dielectric heating device which employs microwave heating, suitable for heating or cooking foodstuffs and suitable for, but not restricted to, use as a domestic or institutional microwave oven.

Abstract: A microwave oven has an oven cavity with a wall (2) formed with a hole (6) covered on an external side of the wall by a metal launch box (8) and choke plate (7). A metal match plate (10) is mounted on the internal side of the wall (2) so that the match plate (10) and the launch box (8) form a launch cavity for delivering microwave energy to the cavity. The choke plate (7) has a peripheral choke channel which prevents leakage of microwave energy between the launch box (8) and choke plate (7), enabling the choke plate (7) and match plate (10) to be bolted to the wall (2).

Abstract: A rotational antenna has a circular portion having a disc-like shape and a cylindrical portion connected to the central portion of the circular portion, and rotates in a direction perpendicular to the sheet with the cylindrical portion serving as an axis. By driving a motor, the motive power is transmitted via a motor shaft and the cylindrical portion to the rotational antenna, thereby rotating the rotational antenna. A bearing serves the function of a spacer between the cylindrical portion and a waveguide. A spacer is attached on an upper surface of the circular portion. The dimension in the direction of height of a spacer is greater than the distance in the direction of height between a bottom plate and a portion in the vicinity of the central portion of the rotational antenna. Thus, the rotational antenna deflects from its central portion toward its outer edge portion, and is fixed with respect to the up-down direction by spacers and the bearing.

Abstract: A microwave polymerization system for dentistry utilizes specifically controlled microwave energy to cure polymer materials so as to produce dental prosthetics, such as dentures, bridges and crowns, that are made in an extra-oral setting such as a dental laboratory or dental office, and to create dental composites for fillings and veneers that are used in an intra-oral setting directly in the patient's mouth. Unlike the microwave energy delivered by commercial microwave ovens which is controlled by pulsing a maximum voltage pulse on and off at a given duty cycle, the system utilizes metered and controlled microwave energy that is preferably continuous and voltage controlled, and regulates the application of this microwave energy by use of various feedback and control mechanisms.

Abstract: A microwave heating apparatus including a cavity for heating food, a first antenna, which projects into the cavity and is arranged to pass into or through the food in order to irradiate the food internally, and a second antenna arranged to supply microwave radiation into the cavity in order to irradiate the food externally. Microwave energy is supplied to the first and second antennae in such a way that the user can independently control the levels of microwave energy irradiated by the first and second antennae.

Abstract: A combination convection/microwave oven in which a food product is cooked by microwave energy and by a heated airflow provided by a thermal energy source and a blower. The oven is capable of cooking food in a microwave reflective pan. Microwave energy enters the oven below the pan and is guided to a spacing between the pan and oven sides and then reflected by the sides and top of the oven to the food product in the pan. The heated airflow is laminar with an upper layer and a lower layer. The pan is positioned at about the interface of the two layers so that the upper layer is incident on the food product and the lower layer is incident on the bottom of the pan.

Abstract: The invention provides a dielectric heating device. The device includes a plurality of electrically conductive side walls which are electrically interconnected in use and arranged in series to define a heating cavity. At least one pair of adjacent side walls has its walls inclined to each other at a corner having an included angle selected from the group consisting of acute angles and obtuse angles. At least one electromagnetic power source capable of emitting electromagnetic radiation suitable for dielectric heating is arranged to feed waves of such radiation into the cavity with circular polarization of the waves, to cause the cavity to act as a multimode resonant heating cavity.

Abstract: A uniform heating structure for a microwave oven is provided. The structure of the invention includes: a magnetron for generating microwaves, a wave guide for guiding the microwaves generated by the magnetron, a pair of openings for radiating the microwaves guided by the wave guide in the form of circular polarized waves, and a cavity which is shaped in a polyhedron more than a rectangular and in which more than one interior walls constructing the polyhedron slope at a predetermined angle (&thgr;1) excepting a right angle with respect to a neighboring interior wall. With this structure, the microwaves generated by the magnetron are reflected to be delivered to food through a sloping interior wall of the cavity while being radiated to the cavity through the wave guide and the openings, thus ensuring a uniform distribution of the microwaves throughout the food and making the food uniformly cooked.

Abstract: A grain containment vessel equipped with one or more antennas and a vapor extraction system is disclosed. An electromagnetic heating pattern is established throughout the grain volume elevating the bulk temperature, while an air flow is applied throughout the grain volume. The electromagnetic energy desorbs the water and increases the vapor pressure and the air flow carries the heat and water from the containment vessel. A controlled amount of electromagnetic energy is introduced into the grain volume to reduce or eliminate fungus infestation and increase insect mortality.

Abstract: A device and a method for microwave feeding of an oven cavity by means of a coupling slot (1) 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 (5) and slot extensions (6,7) projecting from it at its respective sides, which extension have a substantially smaller cross-dimension than the b-dimension of the main slot part.

Abstract: A microwave heating apparatus including a cavity for heating food, a first antenna, which projects into the cavity and is arranged to pass into or through the food in order to irradiate the food internally, and a second antenna arranged to supply microwave radiation into the cavity in order to irradiate the food externally. The heating apparatus further includes at least one magnetron for supplying microwave energy to the first and second antennae, and control means for allowing a user to independently control the levels of microwave energy irradiated by the first and second antennae.

Abstract: A microwave heating apparatus is used for heating a chromatographic column assembly containing a microwave absorbing material. The microwave heating apparatus includes an antenna transmitting a microwave signal and a resonant cavity containing the chromatographic column assembly. The chromatographic column assembly extends relative to predetermined electromagnetic field strength contours within the resonant cavity to provide a predetermined heating profile along the length of the chromatographic column assembly. For example, a single-mode chromatographic column microwave oven can be used to heat a coiled chromatography column to a desired temperature gradient along its length. Oven design embodiments utilizing coaxial transmission line structures, coaxial resonators, and cylindrical resonators are described. Oven designs are provided to achieve more suitable oven size for fixed operating frequencies. Apparatuses for impedance matching an oven to a microwave source are described.

Abstract: A microwave oven has a stationary wave magnetic field detecting device. The microwave oven includes an antenna sensor having a loop portion which is protruded into a waveguide of the microwave oven, and a wire whose one end is grounded at the waveguide, wherein the wire of the antenna sensor is grounded at an outer side of the waveguide.

Abstract: The microwave oven is provided with a magnetron and a wave guide. The wave guide is formed by a combining portion and a matching portion. The magnetron is provided with a magnetron antenna, and the magnetron antenna projects into the combining portion. The combining portion has one end connected to the matching portion, and has a structure in which the cross-sectional area does not change in the horizontal direction. The matching portion has a structure in which its cross-sectional area increases toward the side surface of a heating chamber. An antenna is provided on a mica board in the portion connecting a matching portion with another matching portion.

Abstract: An opening is formed in a right side of a heating chamber. The opening is covered by a protection cover. A waveguide is connected to the opening. A magnetron is connected to the waveguide. The magnetron has a magnetron antenna. An emission antenna is arranged around the magnetron antenna. A rotating plate is mounted to the protection cover. A plurality of diffusion antennas are mounted to the rotating plate. The diffusion antennas are arranged from the waveguide to the heating chamber.

Abstract: A microwave heating apparatus is used for heating a chromatographic column assembly containing a microwave absorbing material. The microwave heating apparatus includes an antenna transmitting a microwave signal and a resonant cavity containing the chromatographic column assembly. The chromatographic column assembly extends relative to predetermined electromagnetic field strength contours within the resonant cavity to provide a predetermined heating profile along the length of the chromatographic column assembly. For example, a single-mode chromatographic column microwave oven can be used to heat a coiled chromatography column to a desired temperature gradient along its length. Oven design embodiments utilizing coaxial transmission line structures, coaxial resonators, and cylindrical resonators are described. Oven designs are provided to achieve more suitable oven size for fixed operating frequencies. Apparatuses for impedance matching an oven to a microwave source are described.

Abstract: A variable frequency microwave heating apparatus designed to allow modulation of the frequency of the microwaves introduced into a multi-mode microwave cavity for heating or other selected applications. A field-perturbing tool is disposed within the cavity to perturb the microwave power distribution in order to apply a desired level of microwave power to the workpiece.

Abstract: With a device for heating parts 8 made of a microwave absorbing plastic and having a microwave generator 1 that generates microwaves of a certain wavelength, an antenna 4 to which the microwaves are conducted, having at least one free end 5 and a device 6 which surrounds the antenna 4, it is proposed that the device for shielding 6 be designed with a tubular shape, so that the device 6 has an inside diameter smaller than half the wavelength, projects beyond the free end 5 of the antenna and has an opening 7 in its end face. With this device it is possible to achieve a spatially limited and nevertheless homogeneous heating of parts 8. Furthermore a method of heating or welding, shaping or crosslinking parts made of a microwave absorbing plastic using this device is also proposed.