Wave absorbing and transmitting integrated device and antenna cover

Abstract

The present invention provides an integrated wave-absorbing and wave-transmitting device and an antenna cover. The integrated wave-absorbing and wave-transmitting device comprises: a wave-transmitting structure, comprising a first substrate and a metal patch unit located on the opposite surface of the substrate; a wave-absorbing structure, which is arranged on the wave-transmitting structure and comprises a first wave-absorbing unit and a second wave-absorbing unit which are perpendicular to each other, and the first wave-absorbing unit or the second wave-absorbing unit comprises: a second substrate; a plurality of metal segments and a plurality of stop bands, which are all located on the surface of the second substrate; wherein the plurality of metal segments and the plurality of stop bands are connected to form absorption rings in an alternating manner, and the metal patch unit is arranged to be perpendicular to the absorption rings of the first wave-absorbing unit and the absorption rings of the second wave-absorbing unit. The device can achieve high L-band transmittance and high Ku-band absorption in a wide angular range, thereby effectively improving the working environment of the radio equipment.

Description

Technical Field

[0001] The present invention generally relates to the field of communication technology, and more specifically, to an integrated wave absorbing and transmitting device and a radome. Background Art

[0002] With the continuous development of modern electromagnetic technology, the division of the electromagnetic spectrum is becoming more and more detailed, and the boundaries are becoming increasingly unclear. At the same time, the development of electromagnetic technology has also given rise to electromagnetic pollution that threatens human survival. At present, wave absorption is an important means to ensure electromagnetic compatibility between different frequency bands and control electromagnetic pollution. However, wave absorption also has some problems. Wave absorbing structures often have no wave transmission ability, which may cause a certain degree of interference to the operation of radio equipment that should have been working normally.

[0003] There are many common integrated wave absorption and wave transmission structures at present. Metal narrow strips are used to manufacture capacitors and inductors on metal strips loaded with lumped resistors, so that this LC circuit can localize energy in the LC loop at a specific frequency, thereby isolating the resistor and achieving the effect of wave transmission. This structure can realize the integration of wave absorption and wave transmission functions, but because the capacitors and inductors manufactured using metal narrow strips are extremely small in size, they have high requirements for processing. At the same time, the capacitors and inductors will change when the incident angle changes, which will cause the loop resonance to change, affecting the performance of wave absorption and wave transmission. Summary of the invention

[0004] The present invention aims at the defects existing in the prior art and provides a method that can solve the above problems. The present invention proposes an integrated wave-absorbing and wave-transmitting structure with high wave transmittance in the L band and high absorption in the Ku band in a wide angular range, and an antenna cover including the structure.

[0005] According to one aspect of the present invention, there is provided an integrated wave absorbing and wave transmitting device, comprising: a wave transmitting structure, comprising a first substrate and a metal patch unit located on an opposite surface of the first substrate; a wave absorbing structure, arranged on the wave transmitting structure and comprising a first wave absorbing unit and a second wave absorbing unit perpendicular to each other, wherein the first wave absorbing unit or the second wave absorbing unit comprises: a second substrate; a plurality of metal segments and a plurality of stop bands, both of which are located on the surface of the second substrate; wherein the plurality of metal segments and the plurality of stop bands are connected to form absorption rings in an alternating manner, and the metal patch unit is arranged to be perpendicular to the absorption rings of the first wave absorbing unit and the absorption rings of the second wave absorbing unit.

[0006] Preferably, the multiple stop bands include the same first stop band and second stop band; and the multiple metal segments include a first metal segment and a second metal segment, wherein the first metal segment, the first metal segment, the first stop band and the second stop band are connected together as an absorption ring, wherein the first stop band is located between the first end of the first metal segment and the first end of the second metal segment and the second stop band is located between the second end of the first metal segment and the second end of the second metal segment.

[0007] Preferably, the first metal segment and the second metal segment include a semicircular ring and parallel metal segments extended at both ends of the semicircular ring.

[0008] Preferably, the metal patch unit includes a solid metal patch or a metal ring patch.

[0009] Preferably, the centerline length of the metal ring patch is an integer multiple of a wavelength corresponding to the resonant frequency of the metal patch unit.

[0010] Preferably, the metal ring patch also includes concentric inner ring and outer ring, the inner ring is located on the first surface of the first substrate; the outer ring is located on the second surface of the first substrate, wherein the first surface is opposite to the second surface and the centerline length of the metal ring patch is the average of the length of the inner ring and the length of the outer ring.

[0011] Preferably, the wave-transmitting structure further includes: a first dielectric layer, located on the first surface of the first substrate and covering the inner ring; and a second dielectric layer, located on the second surface of the first substrate and covering the outer ring.

[0012] Preferably, the inner ring and the outer ring are square rings, rectangular rings, circular rings or hexagonal rings.

[0013] Preferably, the stop band further comprises an inductor and / or a capacitor.

[0014] According to another aspect of the present invention, there is provided a radome, the radome comprising any one of the above-mentioned integrated wave absorbing and transmitting devices.

[0015] The present invention uses a cascade of a three-dimensional metamaterial and a simple two-dimensional frequency selective surface, and has a simple structure. The integrated wave absorbing and wave transmitting device according to the embodiment of the present invention can achieve high wave transmittance in the L band and high absorption rate in the Ku band within a wide angular range. The integrated wave absorbing and wave transmitting device can be used as a protective cover for devices such as communication antennas and radars, and can achieve wide-band and wide-angle absorption under the premise of ensuring the normal operation of the antenna, thereby ensuring a good antenna working environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 is a schematic structural diagram of an example of an absorbing ring of an absorbing structure according to an embodiment of the present invention;

[0018] Figure 2 is a schematic structural diagram of an example of an inner ring and an outer ring of a wave-transmitting structure according to an embodiment of the present invention;

[0019] Figure 3A and Figure 3B is a front view and a side view of an example of an absorbing structure according to an embodiment of the present invention;

[0020] Figure 4 is a side view of an example of a wave-transmitting structure according to an embodiment of the present invention;

[0021] Figure 5 is a three-dimensional diagram of a wave absorbing and transmitting integrated device according to an embodiment of the present invention;

[0022] Figure 6 is a parallel polarization transmission curve diagram of the wave absorbing and transmitting integrated device according to an embodiment of the present invention;

[0023] Figure 7 is a parallel polarization reflection curve diagram of the wave absorbing and transmitting integrated device according to an embodiment of the present invention;

[0024] Figure 8 is a parallel polarization absorption curve diagram of the wave absorbing and transmitting integrated device according to an embodiment of the present invention;

[0025] Fig. 9 is a vertical polarization transmission curve diagram of the wave absorbing and transmitting integrated device according to an embodiment of the present invention;

[0026] Fig.10 is a vertical polarization reflection curve diagram of the wave absorbing and transmitting integrated device according to an embodiment of the present invention; and

[0027] Fig.11 3 is a vertical polarization absorption curve diagram of the wave absorbing and transmitting integrated device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The present invention realizes an integrated wave absorbing and wave transmitting device by separately designing a wave absorbing structure and a wave transmitting structure, and then cascading them. The currently adopted method is to allow the incident wave to be superimposed with the incident wave after resonant reflection in the wave transmitting structure within the wave absorbing frequency band, and to set a resistor to absorb the electromagnetic wave at a position where the electric field strength is stronger after superposition. Therefore, the wave transmitting structure needs to achieve high wave transmission in the low-frequency L band and high cutoff characteristics in the Ku band. The wave absorbing structure needs to set a resistor at a position where the electric field strength is stronger after the incident wave and the reflected wave are superimposed in the Ku band, and have high wave transmission in the L band. Among them, the L band refers to the radio wave band with a frequency of 1-2GHz, and the Ku band is a frequency band from 12.75-18.1GHz.

[0030] Figure 1 4 is a schematic structural diagram of an example of an absorbing ring of an absorbing structure according to an embodiment of the present invention. Figure 2 1 is a schematic structural diagram of an example of an inner ring and an outer ring of a wave-transmitting structure according to an embodiment of the present invention. Figure 3A and Figure 3B 1 and 2 are front and side views of an example of an absorbing structure according to an embodiment of the present invention. Figure 4 1 is a side view of an example of a wave-transmitting structure according to an embodiment of the present invention. Figure 5 is a perspective view of an integrated wave absorbing and transmitting device according to an embodiment of the present invention. Figure 1-Figure 5 The integrated wave absorbing and transmitting device is described in detail.

[0031] Reference Figure 5According to an embodiment of the present invention, the integrated wave absorbing and wave transmitting device 500 comprises: a wave transmitting structure 508, comprising a first substrate and a metal patch unit located on the opposite surface of the substrate; a wave absorbing structure 510, which is arranged on the wave transmitting structure 508 and comprises a first wave absorbing unit 512 and a second wave absorbing unit 514 which are perpendicular to each other, and the first wave absorbing unit 512 or the second wave absorbing unit 514 comprises: a second substrate; a plurality of metal segments, which are located on the surface of the second substrate; and a plurality of stop bands, which are located on the surface of the second substrate at positions where the reflected wave generated by the incident wave at the wave transmitting structure and the incident wave are superimposed and enhanced, specifically, the plurality of stop bands can be arranged on or near a perpendicular orthogonal line perpendicular to the first wave absorbing unit 512 and the second wave absorbing unit 514, wherein the plurality of metal segments and the plurality of stop bands are connected to form an absorption ring in an alternating manner, and the metal patch unit is arranged to be perpendicular to both the absorption ring of the first wave absorbing unit and the absorption ring of the second wave absorbing unit, specifically, the alternating manner is metal segment-stop band-metal segment-stop band.

[0032] According to an embodiment of the present invention, the wave-transmitting structure has high wave transmittance in the L band and the wave-absorbing structure has high absorption rate in the Ku band. Therefore, the integrated wave-absorbing and wave-transmitting device of the cascaded wave-transmitting structure and the wave-absorbing structure can achieve high wave transmittance in the L band and high absorption in the Ku band, thereby effectively improving the working environment of the radio equipment.

[0033] In the following, refer to the attached Figure 1 , 3 and 5, the absorbing structure is described in detail.

[0034] Reference Figure 5 The wave absorbing structure 510 is arranged on the wave-transmitting structure 508, and includes a first wave absorbing unit 512 and a second wave absorbing unit 514 perpendicular to each other, and the first wave absorbing unit 512 and the second wave absorbing unit 514 are the same wave absorbing unit 300. The wave absorbing unit 300 includes: a second substrate 302; a plurality of metal segments, located on the surface of the second substrate 302; and a plurality of stop bands, located on the surface of the second substrate 302 at the position where the reflected wave generated by the incident wave at the wave-transmitting structure 502 and the incident wave are superimposed and enhanced. Specifically, the plurality of stop bands can be arranged on or near a vertical orthogonal line perpendicular to the first wave absorbing unit 512 and the second wave absorbing unit 514, wherein the plurality of metal segments and the plurality of stop bands are connected in an alternating manner (for example, metal segment-stop band-metal segment-stop band) to form an absorption ring 304 as a ring loop of the wave absorbing unit 300, and the metal patch unit is arranged to be perpendicular to both the absorption ring of the first wave absorbing unit and the absorption ring of the second wave absorbing unit. In one embodiment, referring to Figure 1and 3, a plurality of stop bands include the same first stop band R1 and second stop band R2; and a plurality of metal segments include a first metal segment 116 and a second metal segment 118, wherein the first metal segment 116, the second metal segment 118, the first stop band R1 and the second stop band R2 are connected to form an absorption ring 100, wherein the first stop band R1 is located between the first end of the first metal segment 116 and the first end of the second metal segment 118 (belonging to the same side as the first end of the first metal segment) and the second stop band R1 is located between the second end of the first metal segment 116 and the second end of the second metal segment 118 (belonging to the same side as the second end of the first metal segment). The first metal segment 116 and the second metal segment 118 each include a semicircular ring and parallel metal segments extending at both ends of the semicircular ring, wherein the first metal segment 116 and the second metal segment 118 together form the shape of a track of a sports field, that is, the ends of the same side of the two parallel lines are each connected to a semicircle. In Figure 1 In the illustrated embodiment, the first metal segment 116 includes a semicircular ring 102 and parallel metal segments 106 and 110 extending at both ends of the semicircular ring; and the second metal segment 118 includes a semicircular ring 104 and parallel metal segments 108 and 112 extending at both ends of the semicircular ring. In other embodiments, the absorption ring may also be a polygonal ring such as a square ring, a rectangular ring, a hexagonal ring, etc., and accordingly include a larger number of metal segments and stop bands, for example, including four metal segments and stop bands or six metal segments and stop bands, etc. The stop band includes a resistor, wherein the resistor is used to absorb the constructive interference electromagnetic wave generated by the superposition of the reflected wave and the incident wave. In this embodiment, refer to Figure 1 The resistor is arranged at a symmetrical position in the absorption ring, for example, on parallel opposite sides of the polygon, so that the reflected wave at the symmetrical resistor is superimposed on the incident wave to generate a stronger electromagnetic wave compared to the asymmetrical resistor. The absorption ring converts the energy of the absorbed electromagnetic wave into the internal energy of the resistor. In an optional embodiment, the stop band may also include an inductor and a capacitor.

[0035] In the following, refer to the attached Figure 2 , Figure 4 and Figure 5 The wave-transmitting structure is described in detail. The wave-transmitting structure 508 includes a first substrate and a metal patch unit located on the opposite surface of the substrate. The metal patch unit includes a solid metal patch or a metal ring patch. The centerline length of the metal ring patch is an integer multiple of the wavelength corresponding to the resonant frequency of the metal patch unit. Specifically, refer to Figure 2The metal ring patch 200 further includes a concentric inner ring 204 and an outer ring 202, wherein the inner ring 204 is located on the first surface of the first substrate; the outer ring 202 is located on the second surface of the first substrate, wherein the first surface is opposite to the second surface and the centerline length of the metal ring patch 200 is the average of the length of the inner ring 204 and the length of the outer ring 202. Figure 5 , the wave-transmitting portion 508 further includes: a first dielectric layer 504, located on the first surface of the first substrate 502 and covering the inner ring 204; and a second dielectric layer 506, located on the second surface of the first substrate 502 and covering the outer ring 202. In an embodiment, the inner ring 204 and the outer ring 202 are square rings, rectangular rings, circular rings, hexagonal rings or other polygonal rings. In this embodiment, the inner ring 204 and the outer ring 202 are set to be concentric, so as to reduce the interference of electromagnetic waves. In another embodiment, the hexagonal ring can also make the electromagnetic waves more uniform.

[0036] In a specific example of the present invention, the wave-transmitting structure requires the characteristics of high wave transmission in the L band and high cutoff in the Ku band, so it can be considered to use a frequency selective surface (FSS) to achieve this. However, a single metal patch or metal ring structure is difficult to achieve such a wide-band cutoff in the entire Ku band, so it is considered to use a multi-layer band-stop microstructure superposition with different resonant frequencies. At the same time, the center line length of a simple metal ring patch unit, that is, the average value of the length of its inner ring and outer ring, is an integer multiple of the wavelength corresponding to the resonant frequency of the unit, which can make the first-order resonance corresponding wavelength close to the center line length, and can better control the resonant frequency. Therefore, the technical solution of the present invention uses a metal ring patch unit to realize a wave-transmitting structure.

[0037] In a specific example of an absorbing structure, the absorbing structure requires the characteristics of high wave transmission at low frequency and high absorption in the Ku band. The wave absorbing method adopted by the technical solution of the present invention is to absorb at the position where the incident wave and the reflected wave are superimposed and enhanced after the electromagnetic wave is reflected at the frequency point to be absorbed, and a three-dimensional absorbing structure is also adopted. Resistors are designed at the positions where the incident wave and the reflected wave electric field are superimposed and enhanced corresponding to the two stop bands of the wave-transmitting structure. The two groups of resistors are connected in the incident direction to form a loop by using a semi-metallic ring and extending the metal structure, so as to convert energy into the internal energy of the resistor to achieve the purpose of absorption, and can meet the needs of wave absorption in the entire Ku band.

[0038] The following will use an example as an illustration. Figures 1 to 4As shown, the inner diameter Φ1 of the half metal ring is 2mm to 4mm, for example, Φ1=2.6mm, and the width D1 of the metal ring is 0.1mm to 1mm, for example, D1=0.6mm. The distance L1 between the two metal semi-circular rings in the same plane is 1mm to 4mm, for example, L1=2mm. The extension L2 of the metal ring fracture is 0.1mm to 1.5mm, for example, L2=0.9mm. The resistance R1 is 50Ω to 1000Ω, for example, R1=500Ω. The resistance R2 is 50Ω to 1000Ω, for example, R2=150Ω. The side length L3 of the small metal square ring (i.e., the inner ring) is 3mm to 5mm, for example, L3=4.1mm, the side length L4 of the large metal square ring (i.e., the outer ring) is 5mm to 8mm, for example, L4=5.66mm, and the metal width D2 is 0.1mm to 1mm, for example, D2=0.2mm. The thickness of the metal part is 20μm, and metals such as copper, silver, and gold can be used. The length L5 of the dielectric backboard of the absorbing part is 8mm to 10mm, for example, L5=8mm, the width D3 is 3mm to 8mm, for example, D3=4mm, the thickness H1 is 0.5mm to 2mm, for example, H1=0.8mm, the thickness H2 of the high dielectric skin material on both sides of the reflecting part laminated structure is 0.2mm to 1mm, for example, H2=0.5mm, the thickness H3 of the low dielectric sandwich material is 1mm to 8mm, for example, H3=6mm, wherein the two metal square rings of the transmitting part are respectively placed at the positions P1 and P2, the skin of the wave-transmitting structure and the substrate of the wave-absorbing structure both adopt a dielectric constant ε=3.1, and a loss tangent of 0.6%. The combined structure is as follows Figure 5 The simulation results are shown in Figures 6 to 11 As shown, the statistical average values ​​of the simulation results (for example, at 0°, 10°, 20°, 30°, 40°, 50° and 60°) are shown in Table 1. It can be seen from the simulation results that the purpose of high wave transmission in the L band and high absorption in the Ku band has been achieved.

[0039] Table 1

[0040] TE wave transmission (L) TM wave-transmitting (L) TE absorption (Ku) TM absorption (Ku) 0° 0.8930 0.8936 0.9263 0.9265 10° 0.8915 0.8969 0.9236 0.9252 20° 0.8844 0.9041 0.9186 0.9256 30° 0.8728 0.9161 0.9095 0.9278 40° 0.8514 0.9322 0.8913 0.9132 50° 0.8134 0.9510 0.8533 0.8682 60° 0.7394 0.9673 0.7689 0.7738

[0041] For the purpose of clarity, Figures 6 to 11 The parallel polarization transmission curve, the parallel polarization reflection curve, the parallel polarization absorption curve, the perpendicular polarization transmission curve, the perpendicular polarization reflection curve and the perpendicular polarization absorption curve are shown respectively. S21 in the figure is the transmittance, where "1" in S21 is the incident port and "2" is the exit port. S11 is the reflectance, where "1" in S11 is the incident port.

[0042] from Figure 6 and Fig. 9It can be seen that the integrated wave absorbing and transmitting device has high transmittance in the L band (1-2 GHz) and high cutoff characteristics in the Ku band (12.75-18.1 GHz), for example, it has an obvious local minimum point at 12.2 GHz. Figure 8 and Fig.11 The integrated wave absorbing and transmitting device has a very low absorption rate in the L band and a high absorption rate in the Ku band. Figure 7 and 10 There is no significant change in wave reflectivity.

[0043] The present invention can be used as a protective cover for devices such as communication antennas and radars, and can absorb light in a wide frequency and wide angle range while ensuring the normal operation of the antenna, thereby ensuring a good antenna working environment.

[0044] According to an embodiment of the present invention, a radome is also provided, which includes the aforementioned integrated wave absorbing and wave transmitting device, that is, the integrated wave absorbing and wave transmitting device includes: a wave transmitting structure, including a first substrate and a metal patch unit located on the opposite surface of the substrate; a wave absorbing structure, including a first wave absorbing unit and a second wave absorbing unit perpendicular to each other, located above the wave transmitting structure, the first wave absorbing unit and the second wave absorbing unit include: a second substrate; a plurality of metal segments located on the surface of the second substrate; and a plurality of stop bands located on the surface of the second substrate at a position where the reflected wave generated by the incident wave at the wave transmitting structure and the incident wave are superimposed and enhanced, wherein the plurality of metal segments and the plurality of stop bands are connected in an alternating manner to form an absorption ring and the metal patch unit is arranged to be perpendicular to the absorption ring of the first wave absorbing unit and the absorption ring of the second wave absorbing unit.

[0045] The present invention uses a cascade of a three-dimensional metamaterial and a simple two-dimensional frequency selective surface, and has a simple structure. The integrated wave absorbing and wave transmitting device according to the embodiment of the present invention can achieve high wave transmission in the L band and high absorption in the Ku band in a wide angular range. The integrated wave absorbing and wave transmitting device can be used as a protective cover for devices such as communication antennas and radars, and can achieve wide-band and wide-angle absorption under the premise of ensuring the normal operation of the antenna, thereby ensuring a good antenna working environment.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wave absorbing and transmitting integrated device, characterized in that: include: A wave-transmitting structure, comprising a first substrate and a metal patch unit located on an opposite surface of the first substrate; The wave absorbing structure is arranged on the wave-transmitting structure and comprises a first wave absorbing unit and a second wave absorbing unit which are perpendicular to each other, wherein the first wave absorbing unit or the second wave absorbing unit comprises: a second substrate; a plurality of metal segments and a plurality of stop bands, both located on a surface of the second substrate; The plurality of metal segments are connected to the plurality of stop bands in an alternating manner to form absorption rings, and the metal patch unit is arranged to be perpendicular to the absorption ring of the first absorbing unit and the absorption ring of the second absorbing unit. The metal patch unit includes a solid metal patch or a metal ring patch, and the stop band includes an inductor and / or a capacitor.

2. The integrated wave absorbing and transmitting device according to claim 1, characterized in that: The plurality of stopbands include identical first and second stopbands; and The multiple metal segments include a first metal segment and a second metal segment, wherein the first metal segment, the first metal segment, the first stop band and the second stop band are connected together as an absorption ring, wherein the first stop band is located between a first end of the first metal segment and a first end of the second metal segment, and the second stop band is located between a second end of the first metal segment and a second end of the second metal segment.

3. The integrated wave absorbing and transmitting device according to claim 2, characterized in that: The first metal segment and the second metal segment include a semicircular ring and parallel metal segments extended at both ends of the semicircular ring.

4. The integrated wave absorbing and transmitting device according to claim 1, characterized in that: The center line length of the metal ring patch is an integral multiple of a wavelength corresponding to the resonant frequency of the metal patch unit.

5. The integrated wave absorbing and transmitting device according to claim 4, characterized in that: The metal ring patch also includes a concentric inner ring and an outer ring, The inner ring is located on the first surface of the first substrate; The outer ring is located on the second surface of the first substrate, wherein the first surface is opposite to the second surface and the centerline length of the metal ring patch is an average of the length of the inner ring and the length of the outer ring.

6. The integrated wave absorbing and transmitting device according to claim 5, characterized in that: The wave-transmitting structure further comprises: A first dielectric layer, located on the first surface of the first substrate and covering the inner ring; and The second dielectric layer is located on the second surface of the first substrate and covers the outer ring.

7. The integrated wave absorbing and transmitting device according to claim 5, characterized in that: The inner ring and the outer ring are square rings, rectangular rings, circular rings or hexagonal rings.

8. A radome, characterized in that: The antenna cover includes the integrated wave absorbing and transmitting device according to any one of claims 1-7.

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