Radar device

Abstract

A radar device is shown and described, the radar device having a circuit board, at least one electronic component and at least one antenna, wherein the electronic component is arranged on the circuit board and is used at least to generate a high-frequency signal, the radar device having at least one line structure included by the circuit board, for guiding the high-frequency signal from the electronic component to the area of ​​the antenna, wherein the line structure radiates the high-frequency signal in an open radiation area and applies the radiated high-frequency signal to the antenna. The circuit board has at least four conductive layers running substantially parallel to each other, which are isolated from each other by at least three electrically insulating layers, the electronic component is arranged on a first conductive outer layer of the circuit board, the antenna is at least partially constructed in a second outer layer of the circuit board, and the high-frequency signal generated by the electronic component is transmitted to the antenna constructed at least partially in the second conductive outer layer of the circuit board via the area of ​​the conductive inner layer and the electrically insulating inner layer of the circuit board.

Description

Technical Field

[0001] The present invention relates to a radar device, which comprises a circuit board, at least one electronic component and at least one antenna, wherein the electronic component is arranged on the circuit board and is used at least to generate a high-frequency signal, and the radar device comprises at least one line structure included by the circuit board, which is used to guide the high-frequency signal from the electronic component to the area of ​​the antenna, wherein the line structure radiates the high-frequency signal in an open radiation area and applies the radiated high-frequency signal to the antenna. Background Art

[0002] The aforementioned radar devices have long been known from the prior art from various fields of application, for example from fill level measurement technology or also from the automotive sector. Radar devices of the type described often have not only a single antenna and a single electronic component for generating a high-frequency signal, but can have multiple antennas and multiple electronic components for generating different - for example phase-shifted - high-frequency signals. This makes it possible to achieve antenna arrays in which, by corresponding control, high-frequency signals, for example phase-shifted, are generated electronically and thus a directional effect can be achieved (patch antenna array, flat antenna).

[0003] It is known in the prior art that the antenna and the line structure are arranged on one side of the circuit board, on which the electronic components for generating the high-frequency signal are also arranged. The advantages of this arrangement are the relatively simple high-frequency design on only one circuit board plane and the simple antenna structure that is achieved. This has disadvantages with regard to the process isolation that is partly required, since the electronics are arranged on the antenna side and thereby also on the side of the circuit board that faces the process to be monitored. There may also be problems with regard to explosion protection requirements. Summary of the invention

[0004] It is therefore an object of the present invention to specify a radar device in which the above-mentioned disadvantages from the prior art are at least partially avoided.

[0005] In the radar device described at the outset, the resulting object is firstly and essentially achieved in the following manner: the circuit board has at least four conductive layers running essentially parallel to one another, the at least four conductive layers being separated from one another by at least three electrically insulating layers, so that two conductive outer layers of the circuit board, namely the first conductive outer layer and the second conductive outer layer, are formed by two of the at least four conductive layers and the remaining at least two conductive layers form the conductive inner layer of the circuit board, wherein the first conductive inner layer is adjacent to the first conductive outer layer and wherein the second conductive inner layer is adjacent to the second conductive outer layer; and the at least three electrically insulating layers all form the electrically insulating inner layer of the circuit board. As a result, the following structure is visible along the surface normal direction of the layers running parallel to one another of the circuit board: first conductive outer layer, electrically insulating inner layer, first conductive inner layer, another electrically insulating inner layer, second conductive inner layer, another electrically insulating inner layer, and second conductive outer layer. However, if further conductive layers are to be implemented, it remains in this structure that the first conductive layer and the second conductive layer form the conductive outer layers of the circuit board and all electrically insulating layers form the electrically insulating inner layer; i.e. the number of electrically insulating layers is always less than the number of conductive layers.

[0006] The radar device according to the invention is also characterized in that the electronic components are arranged on the first outer layer of the circuit board, which first outer layer thus forms the mounting side of the circuit board. In addition, according to the invention, the antenna is at least partially constructed in the second conductive outer layer of the circuit board, that is, it is usually constructed as a so-called patch, the size of which depends on the wavelength of the high-frequency signal to be emitted. In general, in the radar device according to the invention, the high-frequency signal generated by the electronic components is transmitted through the area of ​​the conductive inner layer and the electrically insulating inner layer of the circuit board to the antenna at least partially constructed in the second outer layer of the circuit board. Then, the high-frequency signal is finally radiated into the external space via the antenna.

[0007] The described design has the advantage that a strict separation is achieved between the process side, i.e. the side on which the antenna is implemented, and the installation side, i.e. the side on which the electronic component - or also a plurality of components - is arranged. This separation makes it possible to achieve a particularly compact design, in particular when the radar device has a plurality of antennas and a plurality of electronic components.

[0008] If different conductive layers are mentioned in the circuit board construction, this does not mean that the conductive layers conduct electricity continuously, i.e. form a continuous metal layer, because it is naturally impossible to realize a radar device according to this understanding. The professional understanding is that non-conductive structures can also be constructed within the conductive layer, for example, in such a way that metal spraying has not been performed in the relevant area or the conductive layer has been removed. This is a common and professional understanding of the reasonable realization of a multi-layer circuit board. That is, different conductive structures can be constructed in the corresponding conductive layers, and these different conductive structures are electrically insulated from each other.

[0009] In a preferred embodiment of the radar device, it is provided that the electrically insulating layer has a thickness of 50 μm to 200 μm, in particular a layer thickness between 90 μm and 110 μm. It is also preferably provided that the electrically insulating layer is composed of a high-frequency substrate, which has a slight attenuation for electromagnetic waves at the frequency of the high-frequency signal. This ensures that the high-frequency signal radiated by the radiation region of the line structure can be transmitted through the circuit board with as little attenuation as possible, which is naturally a prerequisite that the conductive layer has cutouts in the corresponding areas, that is, the conductive layer is not formed in these cutouts.

[0010] According to a further advantageous embodiment, the conductive inner layer has a layer thickness of 10 μm to 30 μm, in particular 15 μm to 21 μm, wherein the conductive inner layer is preferably formed from copper. These layer thicknesses allow forming a line structure sufficient for the present purpose within the conductive inner layer.

[0011] It is particularly preferred that the conductive outer layer has a layer thickness of 15 μm to 60 μm, in particular a layer thickness of 40 μm to 55 μm, wherein the conductive outer layer is preferably also formed from copper. Preferably, the greater layer thickness of the conductive outer layer relative to the layer thickness of the conductive inner layer is achieved by firstly designing all conductive layers to be of equal thickness and then electroplating a further copper layer onto the conductive outer layer. This electroplating is achieved, for example, by producing conductive through-holes in the circuit board, wherein additional conductive material is electroplated onto the through-hole walls in the circuit board, so that a corresponding material thickness is then also deposited on the already existing conductive outer layer and contributes to its thickening.

[0012] If the layer thicknesses described above are used, the circuit board structure is generally obtained, which is flexible but not particularly mechanically stable, so that, for example, the installation side, that is, the first conductive outer layer, of the circuit board with electronic components may also cause problems. For this reason, in a preferred embodiment, it is also provided that a reinforcement layer is fixed to the second conductive outer layer, in particular the reinforcement layer is laminated or glued to the second conductive outer layer, wherein the reinforcement layer preferably consists of a metallized non-metal or of a metal. The non-metal is preferably a composite material, preferably a composite material made of glass fiber cloth and epoxy resin, such as FR4. As a result, the circuit board obtains a mechanically stable structure, which not only simplifies the implementation in terms of the production of the circuit board, that is, for example, also in terms of the installation of the circuit board, but also enables the circuit board to be used in harsh environments. Preferably, metallization is provided on both sides of the reinforcement layer, alternatively only on the outer side of the reinforcement layer, that is, no metallization is provided on the connection side of the reinforcement layer to the second conductive outer layer.

[0013] In order to achieve sufficient stability of the printed circuit board as a whole, it is preferably provided that the reinforcement layer has a thickness of 0.5 mm to 0.9 mm, in particular a thickness of between 0.6 mm and 0.8 mm.

[0014] Another preferred embodiment of the radar device is characterized in that the reinforcement layer has a cutout in the region of the antenna at least partially formed in the second conductive outer layer, in particular wherein the delimiting edge of the cutout is metallized. As a result, the radiation characteristics of the antenna are influenced to a certain extent, for example, a better directional effect can be achieved than in the case of an embodiment without the proposed reinforcement layer.

[0015] Another preferred design of the radar device is characterized in that, viewed along the surface normal of the conductive layers from the first outer layer to the second outer layer, three of the conductive layers are implemented with: a radiation zone of a line structure for guiding high-frequency signals; a fine hole for passing electromagnetic radiation emitted by the radiation zone of the line structure in a defined manner; and an antenna in the second conductive outer layer. That is, in general, an aperture-coupled patch antenna is implemented in this way. The electromagnetic wave emitted by the radiation zone of the line structure passes through the fine hole (which is different from the preferably slit-shaped opening in the relevant conductive layer) to the antenna in the second conductive outer layer, and then the antenna outputs the electromagnetic wave into free space according to excitation. The radiation zone of the line structure, the fine hole and the antenna in the second conductive outer layer can be matched to each other in terms of geometry to meet certain requirements regarding polarization, bandwidth and radiation characteristics, but this is not the subject of the present invention in detail.

[0016] A preferred design of the aperture-coupled antenna described above is that a radiation zone of a line structure for guiding high-frequency signals is implemented in a first conductive outer layer, a fine hole is implemented in a first conductive inner layer, and a coarse hole is implemented in a second conductive inner layer, wherein the coarse hole is larger than the fine hole and is used to allow electromagnetic radiation passing through the fine hole to pass unimpeded to the antenna at least partially constructed in the second conductive outer layer. The coarse hole is constructed to be significantly larger than the fine hole and simply allows the electromagnetic radiation shaped by the fine hole to pass over a large area relative to the fine hole, so as to affect the radiation as little as possible. If the line structure is implemented as a stripline or microstrip line, the stripline is an asymmetric stripline in the described structure.

[0017] An alternative design solution is to realize the radiation area of ​​the line structure for guiding the high-frequency signal in the first conductive inner layer, realize the fine hole in the second conductive inner layer; and the first conductive outer layer realizes metal shielding in the radiation area of ​​the line structure for guiding the high-frequency signal. If the line structure is realized as a stripline in this configuration, the stripline forms a symmetrical stripline in this arrangement.

[0018] As long as the radar device has only one single antenna, which is then usually fed with only one high-frequency signal, the above-described variants of the radar device as the basis are largely problem-free. However, if a plurality of adjacent antennas are to be implemented within the radar device, which are then usually also fed with different, especially phase-shifted, high-frequency signals, mutual influences of adjacent antennas and adjacent transmission paths from the first conductive outer layer to the second conductive outer layer cannot be excluded and are not desirable. A preferred embodiment of the radar device starts from this point, which is characterized in that a grid-like electromagnetic shielding is implemented by means of a plurality of electrical through-holes between the four conductive layers, more precisely around the radiation area of ​​the line structure for guiding the high-frequency signal, around the fine holes for passing the electromagnetic radiation emitted by the radiation area of ​​the line structure in a defined manner and around the antenna in the second conductive outer layer and around the coarse holes implemented in the second conductive inner layer as applicable. In this way, the final structure consisting of the grid-like electromagnetic shielding, the radiation area of ​​the line structure, the fine holes and the antenna in the second conductive outer layer forms a primitive cell. The described design makes it easy to construct a plurality of primitive cells in the radar device, wherein the primitive cells can also be constructed close together. The electrical vias between the four conductive layers must be selected to be close so that the electromagnetic waves transmitted in each primitive cell cannot overcome the grid-like electromagnetic shielding.

[0019] In order to achieve the highest possible density of the primitive cells, it is also preferably provided that the dimensions of the grid-shaped electromagnetic shielding and thereby the primitive cells are selected at most so that a plurality of primitive cells can be arranged on a preferably hexagonal grid at a spacing of half a wavelength or even a whole wavelength of the high-frequency signal to be radiated. It can be provided that the grid-shaped electromagnetic shieldings of adjacent primitive cells at least partially overlap, that is, two adjacent primitive cells share a single section of the grid-shaped electromagnetic shielding.

[0020] In conjunction with the realization of the grid-like electromagnetic shielding, it is advantageously provided that the grid-like electromagnetic shielding and thereby the unit cells have a circular or hexagonal cross section, viewed in the direction of the surface normals of the electrically conductive layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Now, there are different possibilities for designing and expanding the radar device according to the invention. For this purpose, reference is made to the dependent patent claims of the independent patent claim and to the subsequent description of the exemplary embodiments in conjunction with the drawings. In the drawings:

[0022] Figure 1 An embodiment of a radar device known from the prior art is shown;

[0023] Figure 2 An embodiment of a circuit board for a radar device according to the present invention is shown;

[0024] Figure 3 An embodiment of a circuit board for a radar device according to the invention having a thicker conductive outer layer is shown;

[0025] Figure 4 An embodiment of a circuit board for a radar device having a reinforcement layer according to the present invention is shown;

[0026] Figure 5 An exemplary embodiment of a radar device according to the invention having a cutout in a reinforcement layer is shown;

[0027] Figure 6 A diagram showing different conductive layers for realizing a radar device according to the invention with an asymmetric stripline;

[0028] Figure 7 A diagram showing different conductive layers for realizing a radar device according to the invention with a symmetrical stripline;

[0029] Figure 8 An exemplary embodiment of a circuit board for a radar device according to the invention is shown with electrical vias between all four conductive layers; and

[0030] Fig. 9 An exemplary embodiment of a radar device according to the invention having a plurality of primitive cells is shown. DETAILED DESCRIPTION

[0031] Figure 1 A radar device 1 known from the prior art is shown. The radar device 1 has a printed circuit board 2 and an electronic component 3 and an antenna 4. The electronic component 3 is arranged on the printed circuit board 2 and is used to generate a high-frequency signal. The radar device 1 also has a line structure 5 included by the printed circuit board 2 for guiding the high-frequency signal from the electronic component 3 to the area of ​​the antenna 4, wherein the line structure 5 radiates the high-frequency signal in an open radiation area 6 and applies the radiated high-frequency signal to the antenna 4.

[0032] In accordance with Figure 1 In the schematic diagram of FIG. 4 , the antenna 4 also includes a horn portion for shaping and guiding the radiated electromagnetic wave 7 , but this is not necessary for the implementation of the antenna 4 . Figure 1 The embodiment of the embodiment shown is also a schematic diagram, in which the dimensions of the components shown are not shown to scale. The illustration is selected so that the components, for example the line structure 5, can be seen on their own. It is important in any case that in the embodiment shown, the side of the circuit board 2, on which the electronic component 3 is mounted, is identical to the side on which the antenna 4 is implemented.

[0033] Obviously, this allows a very simple design of the radar device 1 shown, but there are disadvantages here with regard to the desired process isolation and a compact design with a plurality of antennas can only be achieved to a certain extent.

[0034] exist Figures 2 to 9 The following shows different aspects of the radar device 1, which can be used to avoid Figure 1 Various shortcomings of the implementation scheme.

[0035] According to Figure 2 In the embodiment of the circuit board 2, it is clear that the circuit board 2 has four conductive layers 8, 9, 10, 11 extending substantially parallel to one another and being isolated from one another by at least three electrically insulating layers 12, 13, 14. When it is said that the different layers extend "substantially" parallel to one another, it is meant that parallelism is not in the mathematically exact sense, but rather that parallelism in the technically reasonable sense can be achieved in principle - with the usual technically unavoidable errors.

[0036] The two outer layers 8, 11 of the circuit board, namely the first conductive outer layer 8 and the second conductive outer layer 11, are formed by two conductive layers 8, 11 of the at least four conductive layers 8, 9, 10, 11, and the remaining at least two conductive layers 9, 10 form the conductive inner layers 9, 10 of the circuit board 2.

[0037] The first conductive inner layer 9 is adjacent to the first conductive outer layer 8, and the second conductive inner layer 10 is adjacent to the second conductive outer layer 11. These three electrically insulating layers 12, 13, 14 are all electrically insulating inner layers 12, 13, 14 of the circuit board 2.

[0038] The electronic component 3 is arranged on the first outer layer 8, i.e., the mounting side, of the circuit board 2, while the antenna 4 is constructed in the second outer layer 11, i.e., the antenna side, of the circuit board. Therefore, the high-frequency signal generated by the electronic component 3 is transmitted to the antenna constructed in the second outer layer 11 of the circuit board 2 via the region of the conductive inner layer and the electrically insulating inner layer 9, 10, 12, 13, 14 of the circuit board 2. Figure 2 The illustration in FIG. 1 is very schematic. As will also be seen later on from the indicated layer thicknesses, the electronic component 3 must be significantly larger, ie approximately in the order of magnitude of the total thickness of the printed circuit board 2 shown here.

[0039] Figure 2 The illustration in FIG. 1 is also schematic, in which it is not explicitly shown how the antenna 4 is constructed in the second conductive outer layer 11 and how the conductive inner layers 9, 10 of the circuit board 2 are constructed so that the high-frequency signal generated by the electronic component 3 can reach the second conductive outer layer 11 or the antenna 4 constructed in the second conductive outer layer from the first conductive outer layer 8. This is naturally impossible when the conductive inner layers 9, 10 are not interrupted. This also applies to Figures 3 to 4 In the illustration in FIG. 1 , no cuts are made here either in the region in which the required interruptions in the conductive inner layers 9, 10 are realized. Figures 2 to 4 What is important is that the structure of the circuit board 2 becomes clear.

[0040] exist Figures 2 to 9 In the illustrated exemplary embodiment of the radar device 1 in , the electrically insulating layers 12 , 13 , 14 have a thickness of approximately 100 μm and consist of a high-frequency substrate that has a low attenuation for electromagnetic waves at the frequency of the high-frequency signal generated by the electronic component 3 .

[0041] In accordance with Figure 2 The conductive layers 8, 9, 10, 11 in the embodiment have a uniform thickness of about 18 μm, that is, the same is true for the conductive outer layers 8, 11.

[0042] Correspondingly, in accordance with Figure 3 The conductive outer layers 8, 11 in the exemplary embodiment of , which are likewise formed from copper, have a layer thickness of approximately 43 μm. The greater layer thickness of the conductive outer layers 8, 11 is achieved by electroplating copper onto the initially present conductive copper layer having the thickness of the conductive inner layers 9, 10 until the mentioned layer thickness of the conductive outer layers 8, 11 is reached. The ratio of the layer thicknesses of the different conductive layers 8, 9, 10, 11 and the electrically insulating layers 12, 13, 14 is Figures 2 to 5 is roughly reproduced in the

[0043] In accordance with Figure 4 and 5 In an embodiment of the radar device 1 of the embodiment of the invention, a reinforcement layer 15 is fixed on the second conductive outer layer 11, wherein the reinforcement layer 15 is glued to the second conductive outer layer 11 by means of an adhesive layer 24. Here, the adhesive layer 24 has a thickness of about 30 μm. The reinforcement layer 15 consists of a metallized non-metal, wherein the non-metal is a composite material, in the present case a composite material made of glass fiber cloth and epoxy resin, namely FR-4. The reinforcement layer 15 is provided with a metallization 18 on both sides. Here, the reinforcement layer 15 has a thickness of 0.7 mm. Since the adhesive layer 24 is conductive in the present case, the second conductive outer layer 11, the adhesive layer 24 and the metallization 18 form a conductive unit. Even if the adhesive layer 24 is not conductive, the capacitor formed by the second conductive outer layer 11, the electrically insulating adhesive layer 24 and the metallization 18 will form a short circuit in electrical terms during operation due to the high frequency of electromagnetic radiation commonly found in the radar field.

[0044] exist Figure 5In the embodiment of the present invention, a cutout 16 is formed in the reinforcement layer 15 in the region of the antenna 4 formed in the second conductive outer layer 11, thereby forming a delimiting edge 17. The delimiting edge 17 of the cutout 15 is provided with a metallization 18 and is thus metallized. The metallized delimiting edge 17 thus has an influence on the directional effect of the radar device 1.

[0045] exist Figure 5 It is also shown for the first time how the antenna 4 can be implemented in the second conductive outer layer 11 , namely by providing the second conductive outer layer 11 with corresponding interruptions, as a result of which the antenna 4 in the second conductive outer layer 11 is exposed.

[0046] exist Figure 6 and 7 , two different designs with specific geometries are shown, which illustrate how the radar device 1 can be advantageously realized. Only the conductive layers 8, 9, 10, 11 are shown respectively, wherein from top to bottom a first conductive outer layer 8, a first conductive inner layer 9, a second conductive inner layer 10, and a second conductive outer layer 11 are shown. Figure 6 and 7 The common point of the design schemes is that: looking from the first conductive outer layer 8 to the second conductive outer layer 11 along the surface normal of the conductive layers 8, 9, 10, 11, three of the conductive layers 8, 9, 10, 11 are implemented with: the radiation area 6 of the line structure 5 for guiding high-frequency signals; the fine holes 19 for allowing the electromagnetic radiation 7 emitted by the radiation area 6 of the line structure 5 to pass in a defined manner; and the antenna 4 in the second conductive outer layer 11. That is, Figure 6 and 7 The embodiments in the drawings respectively implement aperture-coupled patch antennas.

[0047] In accordance with Figure 6 In the embodiment of the present invention, the radiation area 6 ( Figure 6 a), realizing fine holes 19 in the first conductive inner layer 9 ( Figure 6 b), and realizing the coarse pores 20 in the second conductive inner layer 10 ( Figure 6 c). The coarse hole 20 is larger than the fine hole 19 and is used to allow the electromagnetic radiation 7 passing through the fine hole 19 to pass through unimpeded to the antenna 4 constructed in the second conductive outer layer 11 ( Figure 6 d).

[0048] And in accordance with Figure 7In the embodiment of the present invention, the radiation area 6 of the line structure 5 for guiding the high-frequency signal is realized in the first conductive inner layer 9, and the fine hole 19 is realized in the second conductive inner layer 10. The first conductive outer layer 8 is configured as a metal shield in the radiation area 6 of the line structure 5 for guiding the high-frequency signal. Since the line structure 5 is configured as a strip line here, according to Figure 7 The design of φ1 realizes a symmetrical stripline based on the two-sided shielding caused by the first conductive outer layer 8 and the second conductive inner layer 10 except for the fine hole 19.

[0049] exist Figure 8 In the figure, it is shown that Figure 6 , 7 The special feature of the radar device of FIG. 9 is the electrical vias 21 between the four conductive layers 8, 9, 10, 11, which naturally also extend through the three electrically insulating layers 12, 13, 14. All conductive layers 8, 9, 10, 11 are electrically connected to each other via the vias. Here, the electrical vias 21 are holes with metallized inner walls. Figure 6 , 7 In the exemplary embodiments of FIGS. 1 and 9 , a plurality of such through-hole contacts 21 are implemented.

[0050] By means of the plurality of electrical vias 21 between the four conductive layers 8, 9, 10, 11, a grid-like electromagnetic shielding 22 is achieved, namely around the radiation zone 6 of the conductor structure 5 for guiding the high-frequency signal, around the fine holes 19 for allowing the electromagnetic radiation 7 emitted by the radiation zone 6 of the conductor structure 5 to pass in a defined manner and around the antenna 4 in the second conductive outer layer 11 and, if applicable (according to Figure 6 (In an embodiment) a grid-like electromagnetic shielding 22 is implemented around the coarse hole 20 implemented in the second conductive inner layer 10, so that the final structure consisting of the grid-like electromagnetic shielding 22, the radiation zone 6 of the line structure 5, the fine hole 19 and the antenna 4 in the second conductive outer layer 11 forms a primitive cell 23.

[0051] Therefore, in Figure 6 and 7 2 also shows the structure of the grid-like electromagnetic shielding 22 and also the unit cells 23 layer by layer. Viewed along the surface normal direction of the conductive layers 8, 9, 10, 11, the grid-like electromagnetic shielding 22 and thus the unit cells 23 have a hexagonal cross section.

[0052] at last, Fig. 9The implementation of a plurality of elementary cells 23 within the radar device 1 is shown, and thereby the implementation of a patch antenna field, with which the directional effect of the radar device 1 can also be varied - provided that the different elementary cells are controlled accordingly. Here, the view is from above onto the first conductive outer layer, in which the line structure 5 with its radiation zone 6 is implemented. The fine holes 19 in the first conductive inner layer below are also outlined. The dimensions of the grid-like electromagnetic shield 22 and thereby the elementary cells 23 are selected so that a plurality of elementary cells 23 can be arranged on a hexagonal grid with a spacing of the entire wavelength of the radiated high-frequency signal.

[0053] Reference numerals

[0054] 1 Radar device

[0055] 2 Circuit Board

[0056] 3 Electronic components

[0057] 4 Antenna

[0058] 5 Line structure

[0059] 6 Radiation area of ​​line structure

[0060] 7 Electromagnetic waves

[0061] 8 First conductive outer layer

[0062] 9 First conductive inner layer

[0063] 10 Second conductive inner layer

[0064] 11. Second conductive outer layer

[0065] 12 Electrical insulation layer

[0066] 13 Electrical insulation layer

[0067] 14 Electrical insulation layer

[0068] 15 Reinforcement layer

[0069] 16 Recesses in reinforcement layer

[0070] 17 Delimiting edge of the cutout in the reinforcement layer

[0071] 18 Metal spraying

[0072] 19 Pores

[0073] 20 Coarse hole

[0074] 21 Electrical through hole plating

[0075] 22 Grid-shaped electromagnetic shielding

[0076] 23 Primitive Cell

[0077] 24 Adhesive layer.

Claims

1. A radar device (1), comprising a circuit board (2), at least one electronic component (3) and at least one antenna (4), wherein the electronic component (3) is arranged on the circuit board (2) and is used at least to generate a high-frequency signal, the radar device comprising at least one line structure (5) included by the circuit board (2) for guiding the high-frequency signal from the electronic component (3) to the area of ​​the antenna (4), wherein the line structure (5) radiates the high-frequency signal in an open radiation area (6) and applies the radiated high-frequency signal to the antenna (4), in, The circuit board has at least four conductive layers running substantially parallel to each other, the at least four conductive layers being isolated from each other by at least three electrically insulating layers, so that two outer layers of the circuit board (2), namely the first outer layer and the second outer layer, are formed by at least two of the at least four conductive layers, and the remaining at least two conductive layers form the conductive inner layers of the circuit board (2), wherein the first conductive inner layer (9) is adjacent to the first conductive outer layer (8), and wherein the second conductive inner layer (10) is adjacent to the second conductive outer layer (11), and the at least three electrically insulating layers all form the electrically insulating inner layers of the circuit board (2). The electronic component (3) is arranged on a first conductive outer layer (8) of the circuit board (2). The antenna (4) is at least partially constructed in the second outer layer of the circuit board (2). wherein the high-frequency signal generated by the electronic component (3) is transmitted to an antenna (4) at least partially constructed in a second conductive outer layer (11) of the circuit board (2) via regions of the conductive inner layer and the electrically insulating inner layer of the circuit board (2), and wherein, viewed along the surface normal of the conductive layer from the first conductive outer layer (8) to the second conductive outer layer (11), three conductive layers in the conductive layer are implemented with: a radiation zone (6) of a line structure (5) for guiding the high-frequency signal; fine holes (19) for allowing electromagnetic radiation (7) emitted by the radiation zone (6) of the line structure (5) to pass in a defined manner; and an antenna (4) in the second conductive outer layer (11), It is characterized in that A radiation zone (6) of a line structure (5) for guiding the high-frequency signal is implemented in the first conductive outer layer (8), the fine hole (19) is implemented in the first conductive inner layer (9), and a coarse hole (20) is implemented in the second conductive inner layer (10), wherein the coarse hole (20) is larger than the fine hole (19) and is used to allow electromagnetic radiation (7) passing through the fine hole (19) to reach an antenna (4) at least partially constructed in the second conductive outer layer (11) without hindrance, Alternatively, a radiation zone (6) of a circuit structure (5) for guiding the high-frequency signal is implemented in the first conductive inner layer (9), and the fine hole (19) is implemented in the second conductive inner layer (10); and the first conductive outer layer (8) implements metal shielding in the radiation zone (6) of the circuit structure (5) for guiding the high-frequency signal.

2. The radar device (1) according to claim 1, characterized in that The electrically insulating layer has a thickness of 50 μm to 200 μm.

3. The radar device (1) according to claim 2, characterized in that The electrically insulating layer has a layer thickness of between 90 μm and 110 μm.

4. The radar device (1) according to any one of claims 1 to 3, characterized in that: The electrically insulating layer consists of a high-frequency substrate which has a low attenuation for electromagnetic waves at the frequency of the high-frequency signal.

5. The radar device (1) according to any one of claims 1 to 3, characterized in that: The conductive inner layer has a layer thickness of 10 μm to 30 μm, wherein the conductive inner layer is formed from copper.

6. The radar device (1) according to claim 5, characterized in that The electrically conductive inner layer has a layer thickness of 15 μm to 21 μm.

7. The radar device (1) according to any one of claims 1 to 3, characterized in that: The electrically conductive outer layer has a layer thickness of 15 μm to 60 μm, wherein the electrically conductive outer layer is formed from copper.

8. The radar device (1) according to claim 7, characterized in that The electrically conductive outer layer has a layer thickness of 40 μm to 55 μm.

9. The radar device (1) according to any one of claims 1 to 3, characterized in that: A reinforcement layer (15) is fixed on the second conductive outer layer (11), wherein the reinforcement layer (15) is composed of a metal-sprayed non-metal or a metal, wherein the non-metal is a composite material.

10. The radar device (1) according to claim 9, characterized in that The reinforcement layer (15) is laminated or adhered to the second conductive outer layer (11).

11. The radar device (1) according to claim 9, characterized in that The non-metal is a composite material made of glass fiber cloth and epoxy resin (FR4).

12. The radar device (1) according to claim 9, characterized in that The reinforcement layer (15) has a thickness of 0.5 mm to 0.9 mm.

13. The radar device (1) according to claim 12, characterized in that The reinforcement layer (15) has a thickness between 0.6 mm and 0.8 mm.

14. The radar device (1) according to claim 9, characterized in that A cutout (16) is formed in the reinforcement layer (15) in the region of an antenna (4) formed at least partially in the second electrically conductive outer layer (11), wherein a delimiting edge (17) of the cutout (16) is metallized.

15. The radar device (1) according to any one of claims 1 to 3, characterized in that The line structure (5) for guiding the high-frequency signal is constructed as a strip line.

16. The radar device (1) according to any one of claims 1 to 3, characterized in that: By means of a plurality of electrical vias (21) between the four conductive layers, a grid-like electromagnetic shielding (22) is realized around the radiation zone (6) of the line structure (5) for guiding the high-frequency signal, around the fine holes (19) for allowing the electromagnetic radiation (7) emitted by the radiation zone (6) of the line structure (5) to pass in a defined manner, around the antenna (4) in the second conductive outer layer (11) and, if applicable, around the coarse holes (20) realized in the second conductive inner layer (10), so that the final structure consisting of the grid-like electromagnetic shielding (22), the radiation zone (6) of the line structure (5), the fine holes (19) and the antenna (4) in the second conductive outer layer (11) forms a primitive cell (23).

17. The radar device (1) according to claim 16, characterized in that Viewed along the surface normal direction of the conductive layer, the grid-shaped electromagnetic shield (22) and thereby the unit cell (23) have a circular or hexagonal cross section.

18. The radar device (1) according to claim 16, characterized in that The dimensions of the grid-like electromagnetic shield (22) and thereby the unit cells (23) are selected at most such that a plurality of unit cells (23) can be arranged on a hexagonal grid with a spacing of half a wavelength or even a whole wavelength of the radiated high-frequency signal.

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