Multilayer waveguide with metasurface, arrangement, and method for manufacturing same

Abstract

A multilayer waveguide (1) comprising at least three physical layers (21, 2a, 2b, 2c, ... 2n, 22) assembled as a multilayer waveguide (1), the layers being a top layer (21), one or more intermediate layers (2a, 2b, ... 2n), and a bottom layer (22). The multilayer waveguide (1) comprises a waveguide channel (77) which is an elongated aperture (7) in at least one intermediate layer (2a, 2b, ... 2n). At least one layer (21, 2a, 2b, ... 2n, 22) has a metasurface (3) on a first surface (5a) facing a first adjacent layer, the metasurface (3) surrounding the elongated aperture (7) and comprising a thick section (3a) and a thin section (3b).

Description

[Technical Field]

[0001] The present invention generally relates to a multilayer waveguide transmission line having a layer comprising an electromagnetic metasurface. [Background technology]

[0002] Waveguides are well known in the art and are common components used to conduct electromagnetic waves from one point to another. In its most common designation, a waveguide can be a hollow metal pipe.

[0003] Waves propagating through open space lose power over distance, reducing both the distance and the quality of the waves. For this reason, a waveguide is a structure adapted to guide waves by restricting their propagation in at least one dimension. The concept is to reduce losses by forcing the waves to propagate in a specific direction. In an ideal situation, this would result in the waves losing no power, but this is rarely or never the case. Depending on the waveguide transmission line, there will be losses and leakage, and energy losses will occur when the waves couple to the edges of the waveguide. The waveguide concept has been known for a long time and is used to transmit signals, sound, or light, etc.

[0004] At the same time, the increasing use of wireless communications is driving market demand for waveguides and antenna arrays based on this technology, which in turn is driving demand for compact, inexpensive waveguides.

[0005] One available solution is the substrate integrated waveguide (SIW), a compact waveguide based on printed circuit board (PCB) technology that uses via holes to connect the top and bottom layers. Vias are holes that extend between the layers of the waveguide, connecting at least the top and bottom layers. While cost-effective manufacturing methods exist for substrate integrated waveguides, the need for high-frequency dielectrics increases the cost as the frequency increases.

[0006] Another available solution is the so-called gap waveguide technology. Gap waveguides generally consist of two parts. One part has a pin that forms a barrier that prevents electromagnetic waves from propagating in directions other than the intended waveguide direction. This reduces leakage in such structures. Gap waveguides are suitable for some applications, but are limited in terms of size. The typical height of the pin is the wavelength divided by 2 to 6, i.e., λ / 2 to λ / 6. Summary of the Invention

[0007] While compact waveguide technology is available, there is a need for compact components with reduced losses and leakage. SIW, as an example, has inherent losses that are higher than the corresponding losses of, for example, air-filled hollow waveguides. Therefore, while SIW offers a cost-effective alternative, other solutions are needed. Hollow waveguides generally have other drawbacks. For example, leakage occurs because magnetic fields penetrate metals only a short distance. This leakage can be significant when hollow waveguide structures are fabricated from split blocks if a gap exists between two layers, especially if the gap is horizontal. This is because the electromagnetic waves are tightly confined and only penetrate metals a short distance.

[0008] Dielectric waveguides are another option for reducing leakage, but the nature of the problem is different for such waveguides, e.g., due to non-propagating evanescent waves. This is also why such waveguides require a high level of conductivity between layers to reduce leakage. The high level of conductivity significantly increases production costs and requires very high precision during manufacturing. In addition, losses are generally still higher than for air-filled waveguides.

[0009] Although a useful solution, gap waveguides have limitations in both design and pin asperity size that make them inapplicable to some applications.

[0010] An additional problem with waveguide manufacturing is that current levels of CNC milling and forming often result in poor tolerances in manufacturing methods compared to other methods, such as laser cutting, etching, or chemical etching. This makes waveguide structures difficult and / or expensive to manufacture. This problem is more pronounced for some frequency ranges than others. For example, CNC milling and forming are both common manufacturing methods for waveguides compatible with frequencies below 60 GHz. In the higher E-band and D-band frequency ranges, i.e., 71 GHz to 86 GHz and 110 GHz to 170 GHz, CNC milling and forming becomes very expensive due to the very small differences in how the manufacturing techniques work. Therefore, it may not be suitable in some cases and may not produce the desired results in some cases.

[0011] One object is to provide a new implementation of an air-filled waveguide transmission line that is easy to manufacture.

[0012] Another object is to provide a waveguide that is cost-effective to manufacture.

[0013] Another object is to provide a waveguide and design that can be conveniently used in antenna arrays.

[0014] Another object is to provide a waveguide that can be conveniently used in the design of waveguide filters and diplexers.

[0015] Another object is to provide a waveguide that can be conveniently used for packaging and integration with passive components of active electronic circuits, i.e., power amplifiers (PAs), array antennas, etc.

[0016] Another object is to provide a low leakage multilayer waveguide having stacked but unconnected layers.

[0017] Another object is to provide a multi-layer waveguide that does not require galvanic contact between layers to reduce leakage.

[0018] Another object of the present invention is to provide a multi-layer waveguide that does not require connections between layers to reduce leakage.

[0019] A further object of the present invention is to provide a multilayer waveguide that is more compact than prior art solutions.

[0020] Therefore, a waveguide that is compact yet overcomes at least some of the shortcomings of the prior art would be beneficial.

[0021] The present solution therefore relates to a cost-effective and easy-to-manufacture multilayer waveguide transmission line with an electromagnetic metasurface arranged in a specific configuration. This solution is a compact air-filled waveguide with thin layers stacked together but not connected, overcoming many of the drawbacks of prior art solutions. This solution can advantageously be used with metal layers having a typical thickness of λ / 10 or λ / 15 and a leakage suppression structure depth of λ / 20 or even less than λ / 30. The multilayer waveguide comprises at least three physical layers assembled as a multilayer waveguide. The layers are at least one top layer, one or more middle layers, and one bottom layer. The multilayer waveguide comprises a waveguide channel, which is an elongated aperture in at least one middle layer. At least one layer has a metasurface on a first surface facing a first adjacent layer, the metasurface surrounding the elongated aperture. The metasurface comprises a thick section and a thin section.

[0022] In various embodiments, the waveguide channels are arranged in layers as elongated apertures of different sizes. In some embodiments, all layers have elongated apertures of different sizes. In other embodiments, only some of the layers have corresponding apertures.

[0023] The metasurface is a textured surface with a subwavelength thickness, typically less than λ / 10 in this particular example, comprising thick and thin sections that form the texture.

[0024] One advantage is that the metastructure in the multilayer arrangement produces a leakage reduction effect due to the small gap between the layers and the metasurface. This effect comes from the electromagnetic bandgap. Compared to conventional multilayer waveguides, metasurface structures have the advantage of being small in size and inexpensive to fabricate.

[0025] According to one embodiment, the first face has a flat portion surrounding the metasurface, the thick section having a thickness corresponding to the thickness of the layer in the flat portion, and the thin section having a thickness smaller than the thickness in the flat portion.

[0026] According to one embodiment, the second surface of the intermediate layer faces a second adjacent layer which is flat except for the elongated aperture.

[0027] The metasurface faces a flat surface, creating small air-filled spaces between the layers, forming an electromagnetic bandgap structure.

[0028] According to one embodiment, the layers are separate layers stacked together without any elements extending between them.

[0029] One advantage of this solution is that small gaps can be accommodated between all or some of the layers without increasing leakage.

[0030] According to one embodiment, each thick section has any one of the following shapes: circular, oval, triangular, square, pentagonal, rectangular, square, hexagonal, or rectangular.

[0031] One advantage is that the shape of the thickened sections can be varied between different layers or between different waveguides.

[0032] According to one embodiment, said thickened sections are arranged in rows parallel to said elongated apertures.

[0033] According to one embodiment, the thickened sections are positioned at irregular distances from the elongated aperture.

[0034] According to one embodiment, the thickened sections are arranged in a random pattern surrounding the elongated aperture.

[0035] According to one embodiment, the metasurface surrounds the elongated aperture.

[0036] According to one embodiment, the multilayer waveguide comprises a first intermediate layer, a second intermediate layer, and a third intermediate layer, each having an elongated aperture, and the second intermediate layer further comprises a central member disposed within the elongated aperture.

[0037] In various embodiments, all or some of the layers have a metasurface. In one embodiment, only the middle layer has a metasurface. In another embodiment, at least one of the top and bottom layers has a metasurface. In one embodiment, the metasurface is positioned so that it faces the flat surface of an adjacent layer. That is, in such an embodiment, the two metasurfaces do not face each other.

[0038] According to one embodiment, the multi-layer waveguide comprises a first intermediate layer, a second intermediate layer and a third intermediate layer, and the second intermediate layer is a non-relief layer for an integrated electronic chipset.

[0039] One advantage is that non-rough layers, i.e., layers without metasurfaces, can be used for integration in electronic chipsets.

[0040] According to one embodiment, the thickness difference between the thick and thin sections of the metasurface is less than the wavelength divided by 10.

[0041] According to one embodiment, the thickness difference between the thick and thin sections of the metasurface is less than the wavelength divided by 20.

[0042] According to one embodiment, the thickness difference between the thick and thin sections of the metasurface is less than the wavelength divided by 30.

[0043] One advantage of this solution is that metasurfaces allow for smaller waveguide sizes compared to other available alternatives without increasing leakage. Another advantage is that in multilayer structures combined with metasurfaces, leakage between layers is significantly reduced. While larger metasurfaces are also possible, one clear advantage is that smaller metasurfaces are easier to fabricate than alternatives for the corresponding frequencies.

[0044] According to one aspect, a method for manufacturing the multi-layer waveguide described herein is disclosed.

[0045] According to an embodiment, the metasurfaces of different layers in the multilayer waveguide have an asymmetric configuration.

[0046] One advantage of this solution is that the metasurfaces of each layer in a multilayer waveguide with a metasurface do not need to be identical: For example, the metasurfaces can be arranged so that the thick and thin sections between layers are aligned with each other, or they can be arranged in an asymmetric configuration where the thick and thin sections are not aligned.

[0047] According to one embodiment, the thickened and thinned sections are periodically arranged along the outer periphery of the elongated aperture in each layer.

[0048] According to one embodiment, the metasurface is not identical in each layer.

[0049] According to one embodiment, the central member of the elongated aperture connects to the rest of the layer using a single connection tab that spans the aperture and is an integral part of the layer.

[0050] According to one embodiment, the distance between layers of the multi-layer waveguide is 0 to 20 μm.

[0051] According to one embodiment, the distance between layers of the multi-layer waveguide is 0 to 50 μm.

[0052] According to one embodiment, the multi-layer waveguide is a transmission line implemented as one of an antenna, an antenna array, or a filter.

[0053] One advantage of this solution is that the multi-layer waveguide can be realized as, for example, a grooved waveguide antenna.

[0054] Another advantage of this solution is that multi-layer waveguides can be realized for chipset packages such as MMIC (Monolithic Microwave Integrated Circuit) packages.

[0055] According to one embodiment, the waveguide is made from a single material.

[0056] According to one embodiment, the waveguide is made from a single layer of material coated with a metal.

[0057] According to one embodiment, the multi-layer waveguide is assembled using a non-conductive adhesive.

[0058] According to one embodiment, the layers are directly laminated.

[0059] According to one embodiment, the layers are thin films that are stacked without being connected.

[0060] One advantage is that multilayer waveguides do not require galvanic, electrical, or physical connections between layers. This means that small gaps can exist between layers. These gaps can be, for example, air gaps that are not controlled from the fabrication of the layers. The gaps can be, for example, on the micron (μm) or even atomic level.

[0061] According to one embodiment, the layers are thin metal layers stacked without any connections.

[0062] According to one embodiment, the layers of the multi-layer waveguide are held together by one of the following: conductive glue, insulating glue, or two screws.

[0063] One advantage of this solution is that any form of bonding or adhesive means can be used to hold the layers together, since electrical conductivity is not required between the layers to suppress leakage. However, it should be noted that electrical conductivity does not adversely affect performance; that is, the multilayer waveguides according to the solution described herein perform well regardless of the conductive properties between the layers.

[0064] The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0065] [Figure 1] FIG. 1 shows one embodiment of a multilayer waveguide with a layer with a metasurface, with the top layer shown in an exploded view. [Figure 2] FIG. 2 shows one embodiment of an isometric cross section of an intermediate layer. [Figure 3] FIG. 3 shows an exploded view of one embodiment of a multilayer waveguide having a layer with a metasurface. [Figure 4] FIG. 4 shows a cross section of an embodiment such as that shown in FIG. [Figure 5] Figure 5 shows a cross-section of a portion of the intermediate layer, detailing the thick and thin sections of the metasurface. [Figure 6] Figure 6 shows a cross-section of one embodiment of a metasurface in multiple layers, fabricated using chemical etching as a fabrication method. [Figure 7] FIG. 7 illustrates an embodiment showing a coaxial multilayer waveguide with metasurfaces in multiple layers. [Figure 8] FIG. 8 shows a cross section of one embodiment of a coaxial multilayer waveguide with planar layers between layers with metasurfaces. [Figure 9] Figure 9 shows a cross section of one embodiment of a rectangular multilayer waveguide with a metasurface on the bottom layer. [Figure 10] FIG. 10 shows an embodiment in which the metasurface sections have circular shapes. [Figure 11] FIG. 11 illustrates an embodiment in which thick and / or thin sections are unevenly distributed across the metasurface. [Figure 12] FIG. 12 shows an embodiment in which multiple waveguides are arranged in one unit as a slotted waveguide antenna. [Figure 13] FIG. 13 shows a bottom view of the top layer according to the embodiment shown in FIG. [Figure 14] FIG. 14 shows an embodiment of a multi-layer waveguide arranged as a slotted waveguide antenna. [Figure 15] FIG. 15 shows an embodiment of a multi-layer waveguide arranged as a slotted waveguide antenna, with corrugations along the length of the waveguide channel to reduce unwanted signal propagation. DETAILED DESCRIPTION OF THE INVENTION

[0066] In the following, a detailed description of various embodiments of the present invention will be disclosed with reference to the accompanying drawings. All examples in this specification should be considered as part of the general description and can therefore be combined in any way in a general sense. Individual features of the various embodiments and aspects can be combined or exchanged as long as such combination or exchange does not obviously contradict the overall function of the multilayer waveguide, arrangement, or its manufacturing method.

[0067] Briefly, the present solution relates to a compact multilayer waveguide that does not require electrical or galvanic contact between layers. The multilayer waveguide has metasurfaces in its layers configured as leakage suppression structures to reduce energy leakage between the layers of the waveguide. The metasurfaces comprise multiple thick and thin sections surrounding the waveguide channel.

[0068] 1 shows one embodiment of a multilayer waveguide 1 having multiple layers 21, 1a, 2b, 2c, 22 of the multilayer waveguide. The intermediate layers 2a, 2b, 2c, 2d, 2e each have an elongated aperture 7. The elongated aperture 7, alone or in conjunction with elongated apertures in other layers, forms a waveguide channel 77. The elongated aperture 7 is in some or all of the intermediate layers surrounded by the metasurface.

[0069] Figure 2 shows a cross section of a portion of intermediate layer 2b. The layer comprises an elongated aperture 7, only part of which is visible in Figure 2. The elongated aperture 7 is surrounded by a metasurface 3 comprising a thick section 3a and a thin section 3b. Together, the thick section 3a and the thin section 3b form the metasurface. The metasurface suppresses leakage in a manner that helps guide the wave and keeps it in the waveguide channel 77 of which the elongated aperture 7 is a part.

[0070] 2 further shows flat portions 4 surrounding the metasurface 3. In one embodiment, the flat portions 4 have the same thickness as the thickened sections 3a. In the embodiment shown in FIG. 2, the thickened sections 3a are arranged in linear rows 6a, 6b, and 6c. In one embodiment, the number of linear rows 6a, 6b, and 6c can be one, two, three, or more on any or all sides of the elongated aperture 7.

[0071] FIG. 3 illustrates one embodiment of a multilayer waveguide 1 in which the layers are spaced apart. This exploded view illustrates an important feature of the multilayer waveguide 1: no galvanic, electrical, or physical connection is required between the layers. That is, small gaps may exist between the layers. These gaps may be, for example, air gaps that are not controlled from the fabrication of the layers. The gaps may also be, for example, at the micron or even atomic level. However, it should be noted that the gap size illustrated in FIG. 3 is merely exemplary, and the gap between layers may typically be anywhere between 0 and 15 micrometers.

[0072] FIG. 4 shows a cross section of one embodiment of a multilayer waveguide 1, showing the entrance opening 30 and the exit opening 31. These openings 30, 31 are the openings through which waves enter and exit the waveguide channel 77. FIG. 4 also shows the first and second faces 5a, 5b identified for one intermediate layer 2b. Note that each layer has a first and second face 5a, 5b. The entrance opening 30 and the exit opening 31 need not be located on the bottom layer 22. In another embodiment, the entrance opening 30 and the exit opening 31 are instead located on the top layer 21. In yet another embodiment, the entrance opening 30 and the exit opening 31 are located on different layers. For example, the entrance opening 30 can be located on the top layer 21 and the exit opening 31 can be located on the bottom layer 22, or vice versa.

[0073] FIG. 5 shows a portion of an intermediate layer 2a, 2b, ..., 2n having a metasurface 3, or a portion of a top layer 21 or a bottom layer 22. FIG. 5 shows the thickness difference between the thick section 3a, the flat portion 4, and the thin section 3b. This difference can be, for example, 50-70%, 50-60%, 55-65%, or 60-70% of the total thickness of the layer, although the thickness difference can also vary outside of these ranges.

[0074] Figure 6 shows one embodiment of the metasurface 3. The metasurface 3 is fabricated by metal chemical etching, which creates a characteristic shape at the edges of the metasurface, resulting in a rounded edge. Note that other fabrication methods are also possible, such as CNC or laser cutting.

[0075] 7 shows a coaxial multilayer waveguide 1. The waveguide channel 77 comprises a central member 8 disposed within an elongated aperture 7 of one of the intermediate layers 2a, 2b, 2c, ..., 2n. The central member 8 is attached to the rest of the layers at one or more points that connect the central member to the layers and keep it in place.

[0076] FIG. 8 illustrates one embodiment of a coaxial multilayer waveguide 1. The top layer 21 and the bottom layer 22 have a metasurface 3. Note that in some embodiments, the top layer 21 and the bottom layer 22 have a metasurface 3, while in others they do not. Furthermore, in some embodiments, one or more of the intermediate layers do not have a metasurface 3, as shown in FIG. 8, for example.

[0077] 9 shows another embodiment of a multilayer waveguide 1. The top layer 21 does not have a metasurface, but the middle layers 2a, 2b, 2c and the bottom layer 22 do.

[0078] 10 shows an embodiment of intermediate layers 2a, 2b, 2c, ..., 2n in which thickened sections 3a have a rounded shape. Note that this shape is not critical to functionality, and metasurfaces 3 can have thickened sections 3a with many different shapes, both in the same metasurface 3 and in different metasurfaces 3.

[0079] Figure 11 shows another embodiment in which the thick sections 3a of the metasurface 3 are randomly placed around the elongated aperture 7. While Figure 11 illustrates how the thick sections 3a may be arranged, it should be noted that what is described here are only various possible embodiments, and other arrangements of the thick sections 3a are possible within the scope of the claims. The small gap between the layer and the metasurface provides an electromagnetic bandgap (EBG) structure.

[0080] FIG. 12 shows an exploded isometric view of a multilayer grooved waveguide antenna 40 as one example of a waveguide 1 described herein. The embodiment shown in FIG. 12 includes a top layer 21, a middle layer 2a, and a bottom layer 22. The top layer 21 includes an antenna slot 41 and a corrugation 42 located at one end of the waveguide 1. The middle layer 2a includes an elongated aperture 7 that provides a root shape for each waveguide 1. The bottom layer 22 and top layer 21 include a metasurface 3 that is positioned to surround the elongated aperture 7 of the middle layer 2a.

[0081] The elongated aperture 7 shown in Figure 12 includes support structures to enhance the mechanical support of the layer. The support structures are located within the elongated aperture 7. This provides an embodiment where multiple elongated apertures 7 are located instead of a single aperture running along its entire length. In one embodiment, this is simply for structural support.

[0082] FIG. 13 shows a bottom view of the top layer 21 shown in FIG. 12. As shown, in one embodiment, the top layer 21 comprises a metasurface 3 arranged to surround the elongated aperture 7 of the middle layer 2a. It should be understood that the embodiments shown in FIGS. 12 and 13 are merely examples of how the solutions described herein may be implemented as a grooved waveguide antenna 40. FIGS. 12 and 13 further illustrate how the root shape of the waveguide 1 may vary depending on the implementation. For example, the root shape may be straight in some embodiments, while other embodiments may comprise one or more turns.

[0083] FIG. 14 shows one embodiment of a multilayer waveguide 1 implemented as a grooved waveguide antenna 40. FIG. 15 shows a more complex multilayer waveguide 1 implemented as a grooved waveguide antenna 40. Here, corrugations 42 are arranged to reduce ripple in the transmission pattern. The corrugations 42 reduce surface currents on the top layer, thereby improving the propagation pattern. As shown in FIG. 14, the corrugations 42 extend through the top layer 21 and the middle layer 2a. In another embodiment, where the multilayer waveguide implemented as a grooved waveguide antenna 40 includes additional middle layers 2b, 2c, ..., 2n, the corrugations 42 extend through the top layer 21 and the middle layers 2a, 2b, 2c, ..., 2n. In yet another embodiment, the corrugations 42 extend through at least the top layer 21 and at least some of the middle layers 2a, 2b, 2c, ..., 2n.

Claims

1. A multilayer waveguide (1) comprising at least three physical layers (21, 2a, 2b, 2c, ... 2n, 22) assembled as a multilayer waveguide (1), said layers being a top layer (21), one or more intermediate layers (2a, 2b, ... 2n) and a bottom layer (22), said multilayer waveguide (1) comprising a waveguide channel (77) which is an elongated aperture (7) in at least one intermediate layer (2a, 2b, ... 2n), At least one layer (21, 2a, 2b, ... 2n, 22) has a metasurface (3) on a first side (5a) facing a first adjacent layer, The metasurface (3) surrounds the elongated aperture (7) and comprises a thick section (3a) and a thin section (3b). A multilayer waveguide (1).

2. The first surface (5a) has a flat portion (4) surrounding the metasurface (3), said thick section (3a) having a thickness corresponding to the thickness (L1) of said layer in said flat portion (4); the thinned section (3b) has a thickness (L2) which is smaller than the thickness in the flat portion (4); A multilayer waveguide (1) according to claim 1.

3. the second surface (5b) of said layer (21, 2a, 2b, ... 2n, 22) facing the second adjacent layer is a flat surface except for said elongated aperture (7); A multilayer waveguide (1) according to claim 1 or 2.

4. the layers (21, 2a, 2b, 2c, ... 2n, 22) are separate layers stacked together without any elements extending between the layers (21, 2a, 2b, 2c, ... 2n, 22); A multilayer waveguide (1) according to any one of claims 1 to 3.

5. Each thick section (3a) has one of the following shapes: circular, elliptical, triangular, square, pentagonal, rectangular, quadrangular, square, hexagonal, or rectangular. A multilayer waveguide (1) according to any one of claims 1 to 4.

6. said thickened sections (3a) are arranged in rows (6a, 6b, 6c, ... 6n) parallel to said elongated apertures (7); A multilayer waveguide (1) according to any one of the preceding claims.

7. said thickened sections (3a) being arranged at irregular distances from said elongated apertures (7); A multilayer waveguide (1) according to any one of the preceding claims.

8. The metasurface (3) surrounds the elongated aperture (7). A multilayer waveguide (1) according to any one of the preceding claims.

9. The multi-layer waveguide comprises a first intermediate layer (2a), a second intermediate layer (2b) and a third intermediate layer (2c), each of which comprises an elongated aperture (7); The second intermediate layer (2b) further comprises a central member (8) disposed within the elongated aperture (7). A multilayer waveguide (1) according to any one of the preceding claims.

10. The multilayer waveguide comprises a first intermediate layer (2a), a second intermediate layer (2b) and a third intermediate layer (2c); said second intermediate layer (2b) being a non-relief layer for an integrated electronic chipset; A multilayer waveguide (1) according to any one of the preceding claims.

11. The thickness difference (L3) between the thick section (3a) and the thin section (3b) of the metasurface (3) is less than the wavelength divided by 20; A multilayer waveguide (1) according to any one of the preceding claims.

12. The thickness difference (L3) between the thick section (3a) and the thin section (3b) of the metasurface (3) is less than the wavelength divided by 25; A multilayer waveguide (1) according to any one of the preceding claims.

13. One of the top layer (21) and the bottom layer (22) comprises a metasurface (3); A multilayer waveguide (1) according to any one of the preceding claims.

14. The multilayer waveguide (1) is realized as a waveguide slot antenna (40). A multilayer waveguide (1) according to any one of the preceding claims.

15. The top layer (21) comprises an antenna slot (41). A multilayer waveguide (1) according to any one of the preceding claims.

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