Microwave near-field applicator and system

Abstract

Microwave near-field applicator (1) for near-field coupling of microwaves into a composite material (M) in order to locally at least partially melt a thermoplastic matrix of the composite material (M), wherein the microwave near-field applicator (1) comprises: - a flattened application end section (2) which extends longitudinally along a first longitudinal axis (L1) of the microwave near-field applicator (1) and which has an application surface (A), wherein the application surface (A) extends in an end plane (E) of the application end section (2) parallel to the first longitudinal axis (L1), - a connecting end section (3) which extends longitudinally along a second longitudinal axis (L2) of the microwave near-field applicator (1) and which is designed for connecting the microwave near-field applicator (1) to a microwave generator (20), - an electrically conductive inner conductor element (4) and an electrically conductive return conductor tube body (5) capacitively coupled to the inner conductor element (4), wherein the inner conductor element (4) and the return conductor tube body (5) extend coaxially longitudinally from the application end section (2) to the connection end section (3), - wherein the inner conductor element (4) and the return conductor tube body (5) are bent between the application end section (2) and the connection end section (3) such that the second longitudinal axis (L2) is perpendicular, for example perpendicular, to the end plane (E) of the application end section (2).

Description

[0001] The invention relates to a microwave near-field applicator for near-field coupling of microwaves into a composite material in order to locally melt a thermoplastic matrix of the composite material, in particular in a spot to be heated. The invention also relates to a system for producing fiber-reinforced composite components with or from ribbon-shaped composite material.

[0002] Composite materials with a thermoplastic matrix and embedded fibers are used to manufacture fiber-reinforced composite components. The composite material, in the form of a strip-shaped and / or sheet-like semi-finished product (particularly one with limited flexibility or flexural rigidity), can be placed on a negative mold for the component to be manufactured, so that the contour of the negative mold is transferred to the composite material. The molded contour can be preserved by melting the thermoplastic matrix of the composite material and then resolidifying it on the negative mold. In the case of a multi-layered composite material, melting the thermoplastic matrix creates a material-uniform bond between the composite material layers.

[0003] From WO 2005 / 002852 A1, it is already known to deposit composite material in the form of a tape with a thermoplastic matrix and embedded fibers to produce a fiber-reinforced composite component, and to melt the matrix using microwave energy and weld it under pressure to a substrate, which may be formed by a previously deposited layer of composite material. EP 2 444 451 A1 proposes a similar procedure.

[0004] It is an object of the present invention to provide a microwave near-field applicator for near-field coupling of microwaves into a composite material in order to locally melt a thermoplastic matrix of the composite material, and a system for producing fiber-reinforced composite components with or from ribbon-shaped composite material, each exhibiting improved properties. In other words, the present invention is specifically aimed at providing a microwave near-field applicator suitable for near-field coupling of microwaves into the composite material, by means of which a thermoplastic matrix of the composite material can be locally melted.In particular, the microwave near-field applicator, integrated into a dispensing head for ribbon-shaped composite material, is intended to create a system for manufacturing fiber-reinforced composite components, in which both the microwave near-field applicator and the system exhibit improved properties. Specifically, the system aims to enable targeted, localized heating of a specific area of ​​the composite material, particularly in a spot-like manner, achieving a particularly high power density within that area. Alternatively or additionally, the system is designed to minimize peripheral microwave radiation.

[0005] This problem is solved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims. The wording of all claims is made explicit by reference to the content of this description.

[0006] A microwave near-field applicator according to the invention is designed for near-field coupling of microwaves into a composite material, in particular a flexible or flexible material, in order to locally at least partially melt a thermoplastic matrix of the composite material, in particular by absorption of the coupled microwaves. The microwave near-field applicator has an application end section that is flattened on one side and extends longitudinally along a first longitudinal axis of the microwave near-field applicator, and which has an application surface, in particular a planar one. The application surface runs, in particular completely, in an end plane of the application end section that is parallel to the first longitudinal axis, in particular a geometric one.The microwave near-field applicator also has a connection end section, located opposite the application end section, which extends longitudinally along a second longitudinal axis of the microwave near-field applicator and is designed for connecting the microwave near-field applicator to a microwave generator. Advantageously, a coupling connector for attaching the microwave near-field applicator to the microwave generator can be provided on the connection end section. The microwave near-field applicator has an electrically conductive inner conductor element and an electrically conductive return conductor tube body capacitively coupled to the inner conductor element. The inner conductor element and the return conductor tube body extend coaxially along the length of the application end section to the connection end section.The inner conductor element and the return conductor tube body run between the application end section and the connection end section in such a curved manner that the second longitudinal axis runs at an angle, for example at right angles or at an angle to the end plane of the application end section.

[0007] The microwave near-field applicator is specifically designed to concentrate the extracted microwaves within a microwave extraction area of ​​the inner conductor element, particularly a spot-shaped area, within the application surface. This allows for a particularly high power density to be provided at the application surface. Furthermore, the microwave near-field applicator enables targeted and localized heating of the specific spot of the composite material to be heated within the application surface by absorbing the coupled microwaves. It has also been shown that when microwaves are coupled into composite material using the microwave near-field applicator, unwanted peripheral radiation into the surrounding environment is particularly low.

[0008] In particular, the inner conductor element functions as an active high-frequency element of the microwave near-field applicator and serves for energy transfer and field shaping. The microwave coupling area of ​​the inner conductor element in the application end section of the microwave near-field applicator is, in particular, the location of maximum field strength and can act as a capacitive probe. Specifically, an electric field is generated, shaped, and coupled out in this microwave coupling area. Advantageously, the inner conductor element is designed without sharp edges or points to avoid local field peaks, sparking, and / or unstable microwave coupling.

[0009] In particular, the return conductor tube body can also be described as an outer shield. It functions primarily as a return conductor and closes an electrical circuit. Specifically, the return conductor tube body limits the electric field and shapes it precisely for coupling at the designated spot where the composite material is to be heated. Furthermore, the return conductor tube body serves to prevent uncontrolled microwave radiation into the surrounding environment.

[0010] Within the scope of this disclosure, the term "composite material" refers throughout to composite materials comprising a thermoplastic matrix with embedded, in particular reinforcing, fibers. The fibers may be selected from the following group: inorganic reinforcing fibers, in particular basalt fibers, boron fibers, glass fibers, ceramic fibers, silica fibers, carbon fibers, quartz fibers; metallic reinforcing fibers, in particular steel fibers; organic reinforcing fibers, in particular aramid fibers, PBO fibers, polyester fibers, nylon fibers, polyethylene fibers, polymethyl methacrylate fibers; natural fibers, in particular flax fibers, hemp fibers, wood fibers, sisal fibers. In the composite material, the fibers may be used in their pure form or in various mixtures of the aforementioned types.It is understood that other composite materials without a thermoplastic matrix may exist in principle – however, these are specifically not meant within the scope of this disclosure.

[0011] A particularly preferred microwave near-field applicator for near-field coupling of microwaves into a composite material is designed in the form of a thermoplastic carbon fiber tape. Such a thermoplastic carbon fiber tape is a ribbon-shaped semi-finished product comprising a matrix component made of or consisting of thermoplastic polymer material, as well as carbon fibers supported by, and in particular embedded within, the matrix component. Optionally, other types of reinforcing fibers may also be present in addition to the carbon fibers. The reinforcing fibers may, in particular, be long or continuous fibers and / or be longitudinally oriented in the longitudinal direction of the carbon fiber tape. Preferably, the ribbon-shaped composite material has a thickness dimension that is smaller than a width dimension of the ribbon-shaped composite material.However, a cord-shaped composite material with essentially the same thickness and width dimensions can also be understood as ribbon-shaped in the sense of the present disclosure.

[0012] Advantageously, the circumferential wall of the return conductor tube is not continuous in one circumferential direction only at the application end section on the application surface. In an embodiment of the invention, the return conductor tube is designed at least partially in the application end section as approximately a half-tube. Alternatively or additionally, the return conductor tube is designed as a solid tube in the connection end section.

[0013] In a further embodiment of the invention, the microwave near-field applicator comprises a separating element, in particular a foil-shaped one, which extends over a flat surface parallel to the end plane and covers an opening formed on the application surface of the application end section. The separating element on the application surface covers an opening edge of the application end section that surrounds the opening, making it impermeable to molten matrix components of the composite material. Alternatively or additionally, the separating element on the application surface covers the microwave output area of ​​the inner conductor element, making it impermeable to molten matrix components of the composite material. Advantageously, the separating element prevents molten matrix components from adhering to the opening edge and / or the microwave output area, thus avoiding contamination.

[0014] In a further embodiment of the invention, the return conductor tube body has an opening edge section of an opening edge of the application end section extending along the end plane of the application end section. In particular, the opening edge, which comprises the opening edge section of the return conductor tube body, extends completely around the end plane.

[0015] In a further embodiment of the invention, the return conductor tube body has an end-opening edge section extending outside the end plane in the application end section. This end-opening edge section defines an axial end opening of the return conductor tube body. The application end section has a cover element that at least partially covers the axial end opening. The cover element has an edge section that extends along the end plane. In particular, the circumferential opening edge of the application end section, especially in the end plane, can each comprise the cover element edge section and the opening edge section of the return conductor tube body in certain areas. The cover element can be detachably and / or permanently connected to the return conductor tube body, and in particular, be made of a single material.

[0016] Advantageously, the cover element can be designed as an end cap, wherein the end cap has a flat or convex covering section that connects axially to the end opening. Alternatively, the cover element can be designed as a web, so that it does not completely cover the axial end opening, but only in an area of ​​the end opening directly adjacent to the application surface.

[0017] In a further embodiment of the invention, the return conductor tube body has a recess in the application end section on a side opposite the application surface, in particular radially, which in particular penetrates the circumferential wall of the tube body radially.

[0018] Advantageously, the microwave near-field applicator features a shell-shaped grid element that covers the recess opposite the application surface. The grid element can be bonded to the return conductor tube body, for example, by soldering. The grid element prevents uncontrolled escape of microwaves emitted by the inner conductor element through the recess. In particular, the grid element increases the efficiency of the microwave near-field applicator by improving the ratio of the supplied electrical energy to the heat energy generated at the application surface through absorption of microwaves coupled into the composite material.

[0019] In a further embodiment of the invention, the inner conductor element is designed with a flat profile, in particular with an inner conductor cross-sectional width of 8.0 mm and an inner conductor cross-sectional height of 4.0 mm. Alternatively, the inner conductor element can be designed with a square profile, in particular with an inner conductor cross-sectional width of 6.0 mm and the same inner conductor cross-sectional height. As a further alternative, the inner conductor element can be designed with a round profile, in particular with an inner conductor cross-sectional diameter of at least 3.0 mm and / or at most 10.0 mm. It is understood that other cross-sectional shapes may also prove advantageous under certain circumstances.

[0020] In a further embodiment of the invention, the microwave near-field applicator further comprises a fixing device for fixing the inner conductor element and the return conductor tube body relative to each other. In particular, the fixing device is arranged in a gap of the microwave near-field applicator that surrounds the inner conductor and is surrounded by the return conductor tube body. In particular, the fixing device can alternatively or additionally consist of an electrically insulating non-polar material. Polypropylene, polyethylene, polytetrafluoroethylene, or polystyrene can be used as the material for the fixing device.

[0021] The fixing device may expediently include at least one spacer. Alternatively or additionally, the fixing device may be formed by at least partially or even completely filling the gap with the material for the fixing device.

[0022] In a further embodiment of the invention, at least one component consisting of a return conductor tube body, inner conductor element, and cover element is formed with or from a metallic material. Copper, brass, steel, or another highly conductive metal alloy is particularly suitable as a metallic material. Alternatively or additionally, at least one surface area of ​​at least one component consisting of a return conductor tube body, inner conductor element, and cover element can have a metallic coating, in particular of silver, gold, or nickel.

[0023] A system according to the invention is designed for the production of fiber-reinforced composite components with or from, in particular, flexible or rigid, tape-shaped composite material, especially in the form of thermoplastic carbon fiber tapes, and comprises a microwave near-field applicator according to the invention as described above. The advantages of the microwave near-field applicator according to the invention, as explained above, also apply to the system according to the invention. The system has a microwave generator to which the connecting end section of the microwave near-field applicator is connected. Furthermore, the system has a dispensing head that is adjustable relative to a substrate, in particular automatically, for dispensing tape-shaped composite material. The substrate can be formed by a negative mold or, optionally, by composite material already lying on the negative mold. The dispensing head carries the microwave near-field applicator.In particular, the dispensing head also carries the microwave generator. The dispensing head and the microwave near-field applicator are coordinated in such a way that the band-shaped composite material can be guided along the application surface of the microwave near-field applicator during dispensing. This allows microwaves to be coupled into the composite material at the application surface, at least partially melting the thermoplastic matrix of the band-shaped composite material locally, thus bonding the locally melted thermoplastic matrix to the substrate. Particularly if the substrate is composite material already applied to the negative mold, the bonding can be achieved primarily by welding.

[0024] Further advantages and features of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are illustrated with reference to the drawings. In this context, identical reference numerals refer to identical, similar, or functionally equivalent components.

[0025] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of this disclosure. Fig. Figure 1 shows a schematic sectional view of an embodiment of a microwave near-field applicator, Fig. Figure 2 shows a schematic perspective view of the microwave near-field applicator according to Fig. 1, Fig. Figure 3 shows a schematic perspective view of another embodiment of the microwave near-field applicator, Fig. Figure 4 shows a further embodiment of the microwave near-field applicator in a schematic perspective view, and Fig. Figure 5 roughly illustrates the structure of a system for manufacturing fiber-reinforced composite components, in which a microwave near-field applicator is selectively applied according to one of the Fig. 1 to 4 can be used.

[0026] System 100 is used to manufacture fiber-reinforced composite components with or from tape-shaped composite material M. For example, System 100 processes composite material M in the form of a thermoplastic carbon fiber tape to produce the fiber-reinforced composite components. In this case, the tape-shaped composite material M has limited flexural elasticity.

[0027] System 100 comprises a microwave generator 20 and a microwave near-field applicator 1. The microwave near-field applicator 1 has a connection end section 3 to which the microwave generator 20 is connected to supply the microwave near-field applicator 1 with energy. System 100 also comprises a dispensing head 30, which is designed for dispensing ribbon-shaped composite material M, in this case in the form of thermoplastic carbon fiber tape. The dispensing head 30 is adjustable relative to a substrate B. The substrate B is formed, for example, by composite material M previously deposited on a negative mold to be used in the production of a respective fiber-reinforced composite component.

[0028] The dispensing head 30 carries the microwave near-field applicator 1. In this case, the dispensing head 30 also carries the microwave generator 20. The dispensing head 30 and the microwave near-field applicator 1 are coordinated in the system 100 such that the ribbon-shaped composite material M is guided along an application surface A of the microwave near-field applicator 1 during the dispensing process, such that microwaves can be coupled out of the microwave near-field applicator 1 and coupled into the composite material M at the application surface A for the local spot-shaped melting of a thermoplastic matrix of the ribbon-shaped composite material M. The microwaves that can be coupled into the composite material M in a spot-shaped area in this way enable spot-shaped heating of the composite material M, as a result of which the matrix of the composite material M melts only locally and can thus bond with the substrate B, in particular weld.

[0029] The microwave near-field applicator 1 has a flattened application end section 2. The application end section 2 extends longitudinally along a first longitudinal axis L1 of the microwave near-field applicator 1. The application end section 2 has the application surface A of the microwave near-field applicator 1. The application surface A is planar and lies in a geometric end plane E of the application end section 2. The end plane E is parallel to the first longitudinal axis L1. The connection end section 3, provided for connecting the microwave generator 20, extends longitudinally along a second longitudinal axis L2 of the microwave near-field applicator 1.

[0030] In the exemplary embodiments, the first longitudinal axis L1 and the second longitudinal axis L2 are orthogonal to each other. However, other embodiments with an angle other than 90° between the first longitudinal axis L1 and the second longitudinal axis L2 are conceivable.

[0031] The microwave near-field applicator 1 has an electrically conductive inner conductor element 4 and an electrically conductive return conductor tube body 5. The return conductor tube body 5 and the inner conductor element 4 are capacitively coupled to each other. The return conductor tube body 5 and the inner conductor element 4 extend coaxially from the application end section 2 to the connection end section 3. Between the application end section 2 and the connection end section 3, the inner conductor element 4 and the return conductor tube body 5 are bent in certain sections. The inner conductor element 4 and the return conductor tube body 5 are bent such that the second longitudinal axis L2 is perpendicular to the end plane E of the application end section 2.

[0032] In the embodiments shown, the second longitudinal axis L2 runs orthogonally to the end plane E. However, other embodiments with an angle other than 90° between the second longitudinal axis L2 and the end plane E are conceivable.

[0033] The return conductor tube body 5 is, in the application end section 2, at least partially designed as an approximately half-tube. Alternatively or additionally, the return conductor tube body 5 can be designed as a solid tube in the connection end section 3, as is the case here.

[0034] The return conductor tube body 5 has an outer diameter of 28 mm and a wall thickness of 2 mm. The return conductor tube body 5 is bent at a defined radius of 90°, resulting in a bend of the microwave near-field applicator 1 with a defined curvature between the straight application end section 2 and the straight connection end section 3. The bend is, for example, uniaxial, meaning it bends around a single imaginary axis. This axis is perpendicular to the longitudinal axes L1 and L2. The bend around this axis can have a radius of, for example, 75 mm, relative to a virtual neutral fiber of the return conductor tube body 5.

[0035] An opening 7 of the application end section 2 is formed at the application surface A. The application end section 3 has, for example, an opening edge 8 which defines the opening 7 around its circumference. The opening edge 8 of the application end section 2, which in particular extends completely around the end plane E, is, for example, partially formed by an opening edge section 10 of the return conductor tube body 5 extending in the end plane E.

[0036] In the area of ​​an axial end opening 11 of the return conductor tube body 5, the opening edge 8 can be partially formed by a cover element edge section 14 of a cover element 13 of the application end section 2 that covers the end opening 11. An end opening edge section 12 of the return conductor tube body 5, defining the axial end opening 11, extends – unlike the cover element edge section 14 – outside the end plane E.

[0037] The cover element 13 can be materially bonded to the return conductor tube body 5, for example by soldering, welding or gluing.

[0038] In the example of the Fig. 1 and Fig. 2. The cover element 13 is curved, more precisely with an approximately quarter-spherical cover area. In contrast, in the example of the Fig. 3. The end cap is flat, i.e., with a flat covering area. In the example of the Fig. 4 the cover element 13 is in turn formed by a bridge that only partially covers the front opening 11, in particular only in an area of ​​the front opening 11 directly adjacent to the application surface A.

[0039] As particularly evident from the presentation of the Fig.As can be further seen in Figure 4, the return conductor tube body 5 can have a recess 15 on a side S opposite the application surface A. The recess 15 can be covered by a shell-shaped grid element 16 of the microwave near-field applicator 1. The shell-shaped grid element 16 can continue flush with an outer contour of the return conductor tube body 5 in the area of ​​the recess 15.

[0040] For example, the microwave near-field applicator 1 has a fixing device 17 by means of which the inner conductor element 4 and the return conductor tube body 5 are fixed relative to each other. The fixing device 17 is, for example, arranged in a gap 18 of the microwave near-field applicator 1, wherein the gap 18 surrounds the inner conductor 4 and is enclosed by the return conductor tube body 5.

[0041] The fixing device 17 consists, for example, of an electrically insulating non-polar material. The fixing device 17 can be designed with separate mounting devices or, for example, as a complete or partial filling of the gap 18 with the electrically insulating non-polar material.

[0042] The microwave near-field applicator 1 can have a separating element 6 that covers the opening 7 on the application surface A. The separating element 6 can, for example, be film-shaped and extend horizontally across the opening 7 parallel to the end plane E. The separating element 6 can cover the edge of the opening 8 on the application surface A, making it impermeable to molten matrix components of the composite material M. Alternatively or additionally, the separating element 6 can cover a microwave coupling area 9 of the inner conductor element 4 on the application surface A, making it impermeable to molten matrix components of the composite material M.

[0043] The return conductor tube body 5 is, for example, made of or with a metallic material. The return conductor tube body 5 can be made of or with copper, brass, steel, or another metal alloy.

[0044] The inner conductor element 4 is, for example, made of or with a metallic material. The inner conductor element 4 can, for example, be made of or with copper, brass, steel, or another metal alloy.

[0045] The cover element 13 is, for example, made of or with a metallic material. The cover element 13 can, for example, be made of or with copper, brass, steel, or another metal alloy.

[0046] At least one surface area of ​​the material of the return conductor tube body 5 can be metal-coated, in particular silver-plated, gold-plated, or nickel-plated. Alternatively or additionally, at least one surface area of ​​the material of the inner conductor element 4 can be metal-coated, in particular silver-plated, gold-plated, or nickel-plated. Furthermore, alternatively or additionally, at least one surface area of ​​the material of the cover element 13 can be metal-coated, in particular silver-plated, gold-plated, or nickel-plated.

[0047] The inner conductor element 4 can, for example, be designed with a flat profile, in particular with an inner conductor cross-sectional width of 8.0 mm and an inner conductor cross-sectional height of 4.0 mm. Alternatively, the inner conductor element 4 can be designed with a square profile, in particular with an inner conductor cross-sectional width of 6.0 mm and the same inner conductor cross-sectional height. As a further alternative, the inner conductor element 4 can be designed with a round profile, in particular with an inner conductor cross-sectional diameter of at least 3.0 mm and / or at most 10.0 mm. Other cross-sectional shapes of the inner conductor element 4 are also conceivable, for example hexagonal or octagonal.

[0048] The return conductor tube body 5 has, at least in those areas where it is designed as a solid tube, an annular cross-section. Other cross-sectional shapes of the return conductor tube body 5 may also be advantageous under certain circumstances, for example rectangular (square or non-square) or hexagonal.

[0049] In particular, the inner conductor 4, the return conductor tube body 5, and the composite material M can be understood as components of an electric field system, with the composite material M representing the component of the field system into which the high-frequency electromagnetic microwave energy is coupled and by which this energy is absorbed. From this perspective, the composite material M to be heated is intended to extract high-frequency energy from the field system and transform this energy into thermal energy. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2005 / 002852 A1

[0003] EP 2 444 451 A1

[0003]

Claims

[1] Microwave near-field applicator (1) for near-field coupling of microwaves into a composite material (M) in order to locally at least partially melt a thermoplastic matrix of the composite material (M), wherein the microwave near-field applicator (1) comprises: - a flattened application end section (2) which extends longitudinally along a first longitudinal axis (L1) of the microwave near-field applicator (1) and which has an application surface (A), wherein the application surface (A) extends in an end plane (E) of the application end section (2) parallel to the first longitudinal axis (L1), - a connecting end section (3) which extends longitudinally along a second longitudinal axis (L2) of the microwave near-field applicator (1) and which is designed for connecting the microwave near-field applicator (1) to a microwave generator (20), - an electrically conductive inner conductor element (4) and an electrically conductive return conductor tube body (5) capacitively coupled to the inner conductor element (4), wherein the inner conductor element (4) and the return conductor tube body (5) extend coaxially longitudinally from the application end section (2) to the connection end section (3), - wherein the inner conductor element (4) and the return conductor tube body (5) are bent between the application end section (2) and the connection end section (3) such that the second longitudinal axis (L2) is perpendicular, for example perpendicular, to the end plane (E) of the application end section (2). [2] Microwave near-field applicator (1) according to claim 1, - wherein in the application end section (2) the return conductor tube body (5) is at least partially formed in an approximately semi-tubular shape; and / or - wherein in the connection end section (3) the return conductor tube body (5) is formed as a solid tube. [3] Microwave near-field applicator (1) according to claim 1 or 2, - further comprising a separating element (6), in particular a foil-shaped element, which extends over a surface parallel to the end plane (E) in order to cover an opening (7) of the application end section (2) formed on the application surface (A), - wherein the separating element (6) on the application surface (A) covers an opening edge (8) of the application end section (3) surrounding the opening (7) and / or a microwave coupling area (9) of the inner conductor element (4) impermeably to molten matrix components of the composite material (M). [4] Microwave near-field applicator (1) according to any one of claims 1 to 3, - wherein the return conductor tube body (5) has an opening edge section (10) extending along the end plane (E) of the application end section (2) of an opening edge (8) of the application end section (2) which in particular completely surrounds the end plane (E). [5] Microwave near-field applicator (1) according to any one of the preceding claims, - wherein in the application end section (2) the return conductor tube body (5) has a front opening edge section (12) extending outside the end plane (E) and defining an axial end opening (11) of the return conductor tube body (5), - wherein the application end section (2) has a cover element (13) which at least partially covers the axial end opening (11), - wherein the cover element (13) has a cover element edge section (14) extending along the end plane (E), - in particular wherein a circumferential opening edge (8) of the application end section (2) has the cover element edge section (14) and an opening edge section (10) of the return conductor tube body (5). [6] Microwave near-field applicator (1) according to any one of the preceding claims, - wherein in the application end section (2) the return conductor tube body (5) has a recess (15) on a side (S) opposite the application surface (A), - in particular wherein the microwave near-field applicator (1) has a shell-shaped grid element (16) covering the recess (15). [7] Microwave near-field applicator (1) according to any one of the preceding claims, - wherein the inner conductor element (4) is designed with a flat profile, in particular with an inner conductor cross-sectional width of 8.0 mm and with an inner conductor cross-sectional height of 4.0 mm; or - wherein the inner conductor element (4) is designed with a square profile, in particular with an inner conductor cross-sectional width of 6.0 mm and an inner conductor cross-sectional height of the same size; or - wherein the inner conductor element (4) is designed with a round profile, in particular with an inner conductor cross-sectional diameter of at least 3.0 mm and / or at most 10.0 mm. [8] Microwave near-field applicator (1) according to any one of the preceding claims, - further comprising a fixing device (17) for fixing the inner conductor element (4) and the return conductor tube body (5) relative to each other, - in particular wherein the fixing device (17) is arranged in a gap (18) of the microwave near-field applicator (1) surrounding the inner conductor (4) and the return conductor tube body (5) and / or is made of an electrically insulating non-polar material. [9] Microwave near-field applicator (1) according to any one of the preceding claims, - wherein at least one of the return conductor tube body (5), inner conductor element (4) and a cover element (13) of the microwave near-field applicator (1) is formed with or from a metallic material; and / or - wherein at least one surface area of ​​at least one of the return conductor tube body (5), inner conductor element (4) and the cover element (13) of the microwave near field applicator (1) has a metal coating. [10] System (100) for the production of fiber composite components with or from ribbon-shaped composite material (M), comprising: - a microwave near-field applicator (1) according to any one of the preceding claims, - a microwave generator (20) to which the terminal end section (3) of the microwave near-field applicator (1) is connected, and - a depositing head (30) adjustable relative to a base (B) for depositing band-shaped composite material (M), - wherein the laying head (30) carries the microwave near-field applicator (1), in particular and the microwave generator (20). - wherein the dispensing head (30) and the microwave near-field applicator (1) are coordinated in such a way that the ribbon-shaped composite material (M) can be guided along the application surface (A) of the microwave near-field applicator (1) during dispensing in such a way that microwaves can be coupled into the composite material (M) at the application surface (A) for at least partial local melting of the thermoplastic matrix of the elongated composite material (M) in order to bond the locally melted thermoplastic matrix to the substrate (B).

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