EP2046093B1

EP2046093B1 - Method and device for homogeneously heating materials by means of high-frequency electromagnetic radiation

Info

Publication number: EP2046093B1
Application number: EP20070019535
Authority: EP
Inventors: Rudolf Dr. Emmerich; Tomaz Lasic; Liliana Chamudis Varan; Inma Roig Asensi
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV; Asociacion de Investigacion de Materiales Plasticos y Conexas AIMPLAS
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV; Asociacion de Investigacion de Materiales Plasticos y Conexas AIMPLAS
Priority date: 2007-10-05
Filing date: 2007-10-05
Publication date: 2014-01-01
Anticipated expiration: 2027-10-05
Also published as: EP2046093A1; ES2455241T3

Description

The present invention relates to a method for heating materials being capable of absorbing high-frequency electromagnetic radiation, in particular microwaves, by means of irradiating said materials with high-frequency electromagnetic radiation, wherein the high-frequency electromagnetic radiation is coupled into said material at a plurality of radiation areas by means of a plurality of microwave antennas. Moreover, the present invention is directed to a device for heating materials being capable of absorbing high-frequency electromagnetic radiation, the device comprising at least one source of radiation capable of generating high-frequency electromagnetic radiation, in particular microwaves, said source of radiation being connected to at least one microwave antenna being capable of incoupling the high-frequency electromagnetic radiation generated by said source of radiation into the material to be heated, wherein the device is provided with a plurality of microwave antennas.
Devices for the generation of high-frequency electromagnetic radiation are well-known in the art in order to heat different types of materials, e.g., meals and drinks (microwave ovens), polymers which are to be plastified (thermoplastics) or cured/cross-linked (thermosetting plastics, elastomers), etc. Usually, the frequency and wavelength of the generated radiation are in the range of microwaves, i.e. between approximately 300 MHz and 300 GHz and between approximately 1 mm and 1 m, respectively, although said parameters may vary in a broader range dependent on the material to be heated.
FR 2 874 473 A1 describes a process for heat treatment of a resilient material. Said process comprises the step of circulating the resilient material on rotating rolls being heated from the inside, wherein the rolls are radiated with microwaves from several microwave sources being spaced apart from each other and being arranged around the circumference of each roll. The rotating cylinders are provided with an inner heating device as well as with infrared sensors on their walls.
WO 97/13136 A1 discloses a microwave processing system for concurrently controlling a plurality of chemical reactions in separate reaction vessels from a single microwave source. Apart from that said device is not adapted for uniformly heating one and the same material, it does not comprise microwave antennas, but containers which surround the reaction vessels serve as resonators thereby producing a diffuse microwave field in each reaction vessel.
One basic problem of the heating by means of high-frequency electromagnetic radiation, in particular microwaves, consists in that a rather inhomogeneous temperature distribution is achieved in the material being heated as conventional incoupling means, e.g. microwave antennas in the form of substantially rectangular or cylindrical wave guides and the like, usually emit a rather acute "jet", in the centre thereof the material tends so get overheated whereas in the circumferential area of this "jet" no significant heating occurs. Furthermore, the radiation field itself generated by an incoupling means, e.g. a microwave antenna, of a source of radiation being capable of generating microwaves, e.g. a magnetron, klystron or the like, tends to be rather inhomogeneous. Moreover, as heating of a material by means of high-frequency electromagnetic radiation is dependent on its material properties, e.g. density, water content, material type and especially absorption capacity for high-frequency electromagnetic radiation, it is practically impossible to provide for a substantially homogeneous heating of the material by means of high-frequency electromagnetic radiation, which not only applies in connection with materials to be heated itself being not very homogenous.
Conventional microwave ovens try to cope with this problem by rotating the material to be heated in order to obtain on the one hand a broader area being exposed to the microwaves and on the other hand to prevent discrete areas of the material from being overheated due to be being exposed to the microwaves over a too long period of time. As far as the use of high-frequency electromagnetic radiation in the field of plastics procession is concerned, e.g. in order to cure or cross-link curable or cross-linkable resins or polymers, the problem above is conventionally also addressed by moving or rotating a mould being filled with the resin or polymer relative to one or more microwave incoupling means or antennas or vice versa.
However, while merely moving the material to be heated relative to a microwave radiation field being generated by appropriate microwave antennas of a microwave radiation source might largely prevent the material from being overheated in certain areas being most exposed to the radiation field, it is obvious that a substantially homogeneous heating of the material cannot achieved in doing so, even if microwave absorbing additives are added to the material to be heated in order to enhance its microwave absorbance.
In addition, in particular in the field of plastics processing, especially in connection with curing or cross-linking resins or polymers or, generally speaking, monomers, dimers, oligomers or polymers, it is often required to observe very strict processing conditions due to the need of having a reproducible curing, cross-linking or polymerisation which can even make it necessary to formulate the resin batch-wise by manual preparation, as the case may be together with fibrous material for reinforcement purposes. As conventional microwave antennas cannot provide for a substantially homogenous and reproducible heating on the occasion of subsequent curing or cross-linking the resin, the latter is usually heated convectively.
In the case of rather large-scale components or products such as boats or hulls, blades of windmills, pipes and the like which are usually manufactured by resin infusion using an appropriate form tool or mould, the formulation often even has to be cured at ambient temperature over a long period of time, because there is no economical and environmental friendly solution for a homogeneous and reproducible heating-technology. Therefore, the manufacturer of such parts has to tailor a resin formulation for the processing (mixing of the resin components, additives, reinforcement fibres etc.) as well as for the curing at ambient temperature. However, while for the processing a rather low viscosity of the resin is beneficial (small molecules, short chain length, substantially no cross-linking) in order to provide for a homogeneous mixture and for a complete impregnation of reinforcement fibres, for the subsequent curing or cross-linking a fast polymerisation of the resin is advantageous which induces a strong increase of the viscosity, and therefore impregnation properties as well as mixing properties decrease drastically. Accordingly, if no change in boundary conditions, e.g. temperature, between the filling process of the mould and the curing or cross-linking process can be performed, the resin formulation has to fulfil conflicting conditions.
US 5 459 301 A describes a method and an apparatus according to the preamble of independent claims 1 and 19 which are intended for treating chemically treated garments with microwaves. According to said document, a plurality of microwave generators is provided in a microwave chamber being further provided with a temperature sensor in order to sense the overall temperature of the garments. Dependent on this temperature, a controller is provided for controlling the microwave generators in order to maintain the desired temperature.
It is therefore an object of the present invention to provide for a method and a device for heating materials being capable of absorbing high-frequency electromagnetic radiation by means of such radiation of the type mentioned by way of introduction, where the above drawbacks are wholly or at least partially eliminated and which are preferably applicable for substantially homogeneously and reproducibly heating and curing or cross-linking resins or polymers.
On the one hand, this object is achieved by a method as defined by way of introduction, the method being characterised in that the microwave antennas are arranged substantially in parallel relationship and the centres of said radiation areas being spaced apart from each other, wherein the temperature of the material is measured in each of said plurality of radiation areas, and the radiation dose provide by each of said plurality of microwave antennas is controlled, dependent on the respective temperature of the respective radiation area, in such a way that a substantially uniform temperature of the material is obtained in all of said plurality of radiation areas.
On the other hand, the above object is achieved by a device as defined by way of introduction, the device being characterised in that said microwave antennas are arranged substantially in parallel rows so that radiation areas are obtained the centres thereof being spaced apart from each other, wherein a temperature measuring means is assigned to each microwave antenna being capable of measuring the temperature of each radiation area, and wherein the radiation dose provided by each microwave antenna is controllable, dependent on the temperature of its radiation area measured by the respective temperature measuring means, in such a way that a substantially uniform temperature of the material to be heated is obtained in the radiation areas of all microwave antennas, respectively.
The invention combines the main advantage of conventionally heating of materials by means of high-frequency electromagnetic radiation being comparatively fast and economical due to a comparatively high effectiveness with the essential further advantage of being able to provide for a substantially homogeneous and reproducible heating of the material in an effective and inexpensive manner due to the possibility of controlling the radiation dose provided by each of the plurality of microwave antennas being spaced apart from each other dependent on the temperature of the respective radiation area of the material being radiated from the respective microwave antenna. In this manner, a local overheating of the material ("hot spots") as well as more or less important temperature gradients in the material are reliably avoided which enables the invention to be particularly applied to plastics procession processes, e.g. curing or cross-linking of curable or cross-linkable resins or polymers for shaped parts of any size and especially also for relatively large-scaled shaped parts as described below in more detail. However, it is obvious for one skilled in the art that the present invention may be useful for heating any material being capable of absorbing high-frequency electromagnetic radiation at least partially and, therefore, the invention must not be regarded as being restricted to the heating of plastics materials.
In an embodiment of the invention, the temperature of the material being heated is measured at least in the central region of each area being radiated, e.g., in the central point of the radiation field being emitted from the respective microwave antenna. For this reason, the temperature measuring means can be arranged in such a way that it is capable of measuring the temperature of at least the central region of the radiation area of the respective microwave antenna, e.g., in the central region of each microwave antenna and thus in alignment with the focus of the latter.
In order to provide for a substantially continuous control of the temperature profile in the material to be heated by the plurality of microwave antennas, the temperature is preferably measured substantially continuously, especially in real-time and in time intervals of, e.g., 0.01 s to 1 s, respectively. In this case, the temperature measuring means is adapted to measure the temperature of the respective radiation area substantially continuously, wherein a data processing means as a central processing unit (CPU) or the like may be provided for processing the temperature data being supplied from all of the temperature measuring means and for controlling the radiation dose being emitted from the respective microwave antenna dependent on the actual temperature, respectively.
Although the temperature of the material being radiated by the plurality of microwave antennas may be basically measured by any suitable temperature measuring means, measurement of the temperature preferably takes place without contact of the measuring means with the material to be heated, in particular by means of infrared sensors.
With regard to the control of the radiation dose provided by each microwave antenna in dependence on the temperature of the respective radiation area of the material to be heated, it can be preferable for each microwave antenna to be connected to an individual source of radiation capable of generating high-frequency electromagnetic radiation, e.g., a magnetron, klystron, maser or the like. In this case, the radiation dose provided by each microwave antenna can be controlled by means of individually controlling the radiation efficiency, in particular the amplitude of the high-frequency electromagnetic radiation, of its respective source of radiation. Alternatively or additionally, the radiation dose provided by each microwave antenna can be controlled by means of individually controlling the duration of generating radiation of its respective source of radiation, e.g., the source of radiation can be pulsed in order to generate discrete pulses of radiation being transmitted to the respective microwave antenna, the duration and/or the frequency of the pulses being controlled dependent on the temperature measured in the respective radiation area. In this manner, the radiation power, in particular the amplitude of the high-frequency electromagnetic radiation, of each source of radiation can be held on a substantially constant level, preferably on an adjustable level or can, of course, be varied additionally.
As an alternative or in addition to controlling the radiation dose provided by the microwave antennas by modifying the radiation power of its respective source of radiation, it is, of course, also possible to modify the radiation dose provided by each microwave antenna by directly affecting its emission properties. This provides for the possibility to reduce the number of radiation sources such as magnetrons, klystrons etc. as all or at least some - controllable - microwave antennas may be connected to one and the same source of radiation. To this end, according to an embodiment of the invention, the radiation dose provided by each microwave antenna is controlled by means of individually influencing the emission properties of the respective microwave antenna, wherein the radiation dose provided by each microwave antenna preferably is controlled by means of varying a magnetic field affecting the respective microwave antenna.
Accordingly, an embodiment of a device according to the invention can be designed in such a way that the radiation dose provided by each microwave antenna is controllable by means of individual interference of the emission properties of the respective microwave antenna. In this regard, according to a preferred embodiment, the emission properties of each microwave antenna of the device can be controllable by means of a magnet being assigned to each microwave antenna, wherein the magnet has a variable magnetic field and is arranged in such a way that its magnetic field is allowed to affect the radiation power of the high-frequency electromagnetic radiation emitted from the respective microwave antenna. Preferably, the magnet having a variable magnetic field is in the form of an electromagnet which is assigned to each microwave antenna.
The electromagnet is suitably in the form of a coil whose windings surround the respective microwave antenna, wherein the coil is connected to a power supply unit such as a voltage or current generator, the power of which is controlled dependent on the temperature measured by the respective temperature measuring means, e.g., by means of a CPU as indicated above.
According to a preferred embodiment of the present invention, the plurality of microwave antennas may be arranged in such a way that the radiation areas thereof overlap partially so that the circumferential areas of each radiation area generated by the plurality of microwave antennas (in which the radiation dose is decreased compared to their central area and, therefore, an inferior heating capacity is obtained) can be radiated by more than one microwave antenna, e.g., by two microwave antennas being positioned adjacently. This may contribute to a very homogenous heating of the material avoiding any serious temperature gradients therein.
The plurality of microwave antennas may be, e.g., arranged in an array, wherein such array preferably can comprise several rows of microwave antenna, the rows being arranged substantially in parallel relationship. In order to provide for a homogenous overall radiation field as possible and, preferably, for a peripheral overlapping of the individual radiation fields being emitted from each microwave antenna, the microwave antennas of at least some rows, in particular of adjacent rows, can be arranged in a staggered relationship, wherein the offset of different or adjacent rows may correspond to the reciprocal value of the number of rows multiplied by the distance of microwave antennas or their radiation area in a row, respectively.
In an embodiment of the invention, the plurality of microwave antennas is arranged on a carrier means, wherein the microwave antennas are movable relative to said carrier means and/or said carrier means is movably mountable on the ground. The displacement of the array of microwave antennas in respect of the carrier means or the displacement of the latter in respect to the ground may be, e.g., ensured through the provision of guide rails, portal cranes, robots or the like. By this means, it is for example possible to move the array of microwave antennas along a shaped part or along a mould being filled with a curable resin in order to provide for a substantially homogenous curing or cross-linking thereof being initiated by the heating by means of high-frequency electromagnetic radiation.
In any case, the material being heated may be selected from a group comprising curable and/or cross-linkable monomers, dimers, oligomers and polymers.
As indicated above, the invention is especially applicable to a thermally initiatable curing of resins or a cross-linking of polymers or, generally speaking, to the curing and/or cross-linking of curable and/or cross-linkable monomers, dimers, oligomers and/or polymers which can be heated to a sufficient temperature in order to substantially homogeneously cure and/or cross-link said monomers, dimers, oligomers and polymers at least partially, wherein the curing/cross-linking process can, of course, be influenced by previously known measures such as the provision of additives in the form of cross-linking agents, accelerators, promoters, hardeners (e.g., substances being capable to be decomposed to radicals such as peroxides etc.), additives being capable of enhancing the microwave absorbance (such as glycols, phthalates, amines etc.) and so on.
In practice, the curable and/or cross-linkable monomers, dimers, oligomers and polymers will be arranged in a mould, wherein the microwave antennas are moved over substantially the entire mould in order to achieve a substantially homogenous curing and/or cross-linking of the curable and/or cross-linkable monomers, dimers, oligomers and/or polymers thereby obtaining a cured and/or cross-linked moulding. For this reason, the device according to the present invention may further comprise a mould being capable of accommodating curable and/or cross-linkable monomers, dimers, oligomers and/or polymers, the microwave antennas being movable over substantially the entire mould in order to achieve a substantially homogenous curing and/or cross-linking of the curable and/or cross-linkable monomers, dimers, oligomers and/or polymers thereby obtaining a cured and/or cross-linked moulding or shaped part.
The invention will now be described in more detail by way of a preferred embodiment of a device for heating materials being capable of absorbing high-frequency electromagnetic radiation according to the present invention and with reference to the accompanying drawings, in which

fig. 1: is a perspective view of an embodiment of a device for heating materials by means of micro-waves according to the present invention; and
fig. 2: is a schematic top plan view of an array of microwave antennas of the device as shown in fig. 1.

Referring to fig. 1, an embodiment of a device 1 for heating materials being capable of absorbing high-frequency electromagnetic radiation such as microwaves comprises a plurality of incoupling means in the form of microwave antennas 2 which may, e.g., be composed of hollow waveguides, coaxial waveguides or the like. Each microwave antenna 2 is connected to an individual source of radiation 3 being capable of generating microwaves such as magnetrons. The microwave antennas 2 are arranged in an array which, in the present embodiment, comprises two parallel rows R₁, R₂ of microwave antennas 2 being positioned equidistantly and in a staggered relationship, wherein the offset of the antennas 2 of the first row R₁ and the ones of the second row R₂ is approximately half the distance of the antennas 2 in the first and second rows R₁, R₂, respectively, in order to provide for a substantially homogenous overall radiation field, the radiation field of the individual antennas 2 overlapping each other peripherally (see also fig. 2).
Referring again to fig. 1, the array of microwave antennas 2 and their sources of radiation or magnetrons 3 are arranged on a carrier means 4 in the form of a frame, wherein the array of microwave antennas 2 is movable relative to the frame 4. For this reason, the array can, for example, be positioned on a slide 5 which is guidably mounted on guide rails 6 being fixedly mounted on the frame 4 in order to be able to be displaced a least translationally along the guides 6. Of course, the array of antennas 2 or the slide 5 can further be displaceable in a direction substantially perpendicular to that of the guides, and/or can be mounted rotatable around a vertical axis (not shown), if need be.
As shown in fig. 2, a temperature measuring means such as an infrared sensor 7, preferably being adapted to deliver measurement signals with regard to the temperature substantially continuously or in real-time, is assigned to each microwave antenna 2 in order to measure the temperature of the material to be heated (not shown) in a radiation area of the material being radiated from the respective antenna 2. The infrared sensors 7 can be arranged in the central region of each antenna 2 or its radiation area, respectively although, of course, more than one sensor may be assigned to each of the antennas 2 in order to measure the temperature of the radiated material in more than one point of the respective radiation area. A control means such as a CPU unit (also not shown) is provided in order to receive the information in regard to the temperature of all infrared sensors 7, and to control the microwave antennas 2, dependent on the respective temperature, in such a way that a substantially uniform temperature of the material to be heated is obtained in the radiation areas of all antennas 2. To this end, the radiation power of the radiation of the respective magnetrons 2 and/or the duration/frequency of discrete pulses of radiation being generated by the respective magnetrons 3 may be controllable dependent on the temperature measured in the respective radiation area.
In a particularly preferred embodiment, the device 1 is further provided with a mould (not shown) being positioned beneath the slide 5 carrying the array of microwave antennas 2 so that the microwaves can be incoupled directly into the mould. The width of the mould should correspond approximately to the width of the array of microwave antennas 2, whereas the length of the mould should not exceed the length of the guide rails 6 so that it is possible for the mould to be radiated substantially over the whole projection thereof by means of moving the array of microwave antennas 2 along the guide rails 6. In any case, the mould should be positionable relative to the microwave antennas 2 in such a way that it is enabled to be radiated by the array of microwave antennas 2 substantially completely, e.g., beneath the array being mounted on the slide 5 which is movably mounted on the guide rails 6. The mould serves to accommodate curable and/or cross-linkable polymer or resins systems such as di or multifunctional acids, anhydrides, alcohols, isocyanates etc., if need be together with suitable additives, reinforcement fibres and so on, the resin system being curable or cross-linkable by means of radiating it with microwaves.
In this manner, mouldings or shaped parts, in particular also large-scale and/or rather complex mouldings such as blades of windmills, hulls etc. can be produced under preadjustable, reproducible and homogeneous curing conditions and in an inexpensive and time-saving manner, e.g. compared to a curing at ambient temperature or a curing employing convective heating.

Claims

A method for heating materials being capable of absorbing high-frequency electromagnetic radiation, in particular microwaves, by means of irradiating said materials with high-frequency electromagnetic radiation, wherein the high-frequency electromagnetic radiation is coupled into said material at a plurality of radiation areas by means of a plurality of microwave antennas (2), characterised in that the microwave antennas (2) are arranged substantially in parallel rows and the centres of said radiation areas being spaced apart from each other, wherein the temperature of the material is measured in each of said plurality of radiation areas, and the radiation dose provide by each of said plurality of microwave antennas (2) is controlled, dependent on the respective temperature of the respective radiation area, in such a way that a substantially uniform temperature of the material is obtained in all of said plurality of radiation areas.
A method as claimed in claim 1, wherein the temperature of the material being heated is measured at least in the central region of each area being radiated.
A method as claimed in claim 1 or 2, wherein the temperature is measured substantially continuously.
A method as claimed in any one of claims 1 to 3, wherein the temperature is measured by means of infrared sensors.
A method as claimed in any one of claims 1 to 4, wherein each microwave antenna (2) is connected to an individual source of radiation (3) capable of generating high-frequency electromagnetic radiation.
A method as claimed in claim 5, wherein the radiation dose provided by each microwave antenna (2) is controlled by means of individually controlling the radiation power, in particular the amplitude of the high-frequency electromagnetic radiation, of its source of radiation (3).
A method as claimed in claim 5, wherein the radiation dose provided by each microwave antenna (2) is controlled by means of individually controlling the duration of generating radiation of its source of radiation (3).
A method as claimed in claim 7, wherein the radiation power, in particular the amplitude of the high-frequency electromagnetic radiation, of each source of radiation (3) is held on a substantially constant level.
A method as claimed in any one of claims 1 to 8, wherein the radiation dose provided by each microwave antenna (2) is controlled by means of individually influencing the emission properties of the respective microwave antenna (2).
A method as claimed in claim 9, wherein the radiation dose provided by the microwave antennas (2) is controlled by means of varying a magnetic field affecting the respective microwave antenna (2).
A method as claimed in any one of claims 1 to 10, wherein the plurality of microwave antennas (2) is arranged in such a way that the radiation areas thereof overlap partially.
A method as claimed in any one of claims 1 to 11, wherein the plurality of microwave antennas (2) is arranged in an array.
A method as claimed in claim 12, wherein the array comprises several rows (R₁, R₂) of microwave antennas (2), the rows (R₁, R₂) being arranged substantially in parallel relationship.
A method as claimed in claim 13, wherein the microwave antennas (2) of at least some rows (R₁, R₂), in particular of adjacent rows (R₁, R₂), are arranged in a staggered relationship.
A method as claimed in any one of claims 1 to 14, wherein the plurality of microwave antennas (2) is arranged on a carrier means (4), wherein the microwave antennas (2) are movable relative to said carrier means (4) and/or said carrier means (4) is movably mountable on the ground.
A method as claimed in any one of claims 1 to 15, wherein the material being heated is selected from a group comprising curable and/or cross-linkable resins, monomers, dimers, oligomers and polymers.
A method as claimed in claim 16, wherein the curable and/or cross-linkable resins, monomers, dimers, oligomers and/or polymers are heated to a sufficient temperature in order to substantially homogeneously cure and/or cross-link said resins, monomers, dimers, oligomers and polymers at least partially.
A method as claimed in claim 16 or 17, wherein the curable and/or cross-linkable resins, monomers, dimers, oligomers and polymers are arranged in a mould, wherein the microwave antennas (2) are moved over substantially the entire mould in order to achieve a substantially homogenous curing and/or cross-linking of the curable and/or cross-linkable resins, monomers, dimers, oligomers and/or polymers thereby obtaining a cured and/or cross-linked moulding.
A device (1) for heating materials being capable of absorbing high-frequency electromagnetic radiation, the device (1) comprising at least one source of radiation (3) capable of generating high-frequency electromagnetic radiation, in particular microwaves, said source of radiation (3) being connected to at least one microwave antenna (2) being capable of incoupling the high-frequency electromagnetic radiation generated by said source of radiation (3) into the material to be heated, wherein the device (1) is provided with a plurality of microwave antennas (2), characterised in that said microwave antennas (2) are arranged substantially in parallel relationship so that radiation areas are obtained the centres thereof being spaced apart from each other, wherein a temperature measuring means (7) is assigned to each microwave antenna (2) being capable of measuring the temperature of each radiation area, and wherein the radiation dose provided by each microwave antenna (2) is controllable, dependent on the temperature of its radiation area measured by the respective temperature measuring means (7), in such a way that a substantially uniform temperature of the material to be heated is obtained in the radiation areas of all microwave antennas (2), respectively.
A device as claimed in claim 19, wherein the temperature measuring means (7) is arranged in the central region of each microwave antenna (2) so that it is capable of measuring the temperature of at least the central region of the radiation area of the respective microwave antenna (2).
A device as claimed in claim 19 or 20, wherein the temperature measuring means (7) is composed of an infrared sensor.
A device as claimed in any one of claims 19 to 21, wherein the device (1) comprises a plurality of sources of radiation (3) capable of generating high-frequency electromagnetic radiation, each source of radiation (3) being connected to an individual microwave antenna (2).
A device as claimed in claim 22, wherein the radiation power, in particular the amplitude of the high-frequency electromagnetic radiation, of the source of radiation (3) of each microwave antenna (2) is individually controllable.
A device as claimed in claim 22, wherein the duration of generating radiation of the source of radiation (3) of each microwave antenna (2) is individually controllable.
A device as claimed in claim 24, wherein the radiation power, in particular the amplitude of the high-frequency electromagnetic radiation, of each source of radiation (3) is adjustable on a constant level.
A device as claimed in any one of claims 19 to 25, wherein the emission properties of each microwave antenna (2) are controllable by means of a magnet being assigned to each microwave antenna (2), wherein the magnet has a variable magnetic field and is arranged in such a way that its magnetic field is allowed to affect the radiation power of the high-frequency electromagnetic radiation emitted from the respective microwave antenna (2).
A device as claimed in claim 26, wherein the magnet is an electromagnet.
A device as claimed in any one of claims 19 to 27, wherein the plurality of microwave antennas (2) is arranged in an array.
A device as claimed in claim 28, wherein the array comprises several rows (R₁, R₂) of microwave antennas (2), the rows (R₁, R₂) being arranged in a substantially parallel relationship.
A device as claimed in claim 29, wherein the microwave antennas (2) of at least some rows (R₁, R₂), in particular of adjacent rows, a arranged in a staggered relationship.
A device as claimed in any one of claims 19 to 30, wherein the plurality of microwave antennas (2) is arranged on a carrier means (4), wherein the microwave antennas (2) are movable relative to said carrier means (4) and/or said carrier means (4) is movably mountable on the ground.
A device as claimed in any one of claims 19 to 31, wherein it further comprises a mould being capable of accommodating curable and/or cross-linkable resins, monomers, dimers, oligomers and/or polymers, the microwave antennas (2) being movable over substantially the entire mould in order to achieve a substantially homogenous curing and/or cross-linking of the curable and/or cross-linkable resins, monomers, dimers, oligomers and/or polymers thereby obtaining a cured and/or cross-linked moulding.