Three-dimensional wideband wave-absorbing structure with enhanced wave-absorbing performance

Abstract

The application discloses a three-dimensional wide-band wave-absorbing body structure with enhanced wave-absorbing performance. The wave-absorbing body structure comprises a planar part and a vertical part. Resonance units and a metal back plate are arranged on the upper and lower surfaces of a double-layer dielectric substrate in the planar part. The vertical part is composed of dielectric plates and resonance units arranged vertically in a cross shape. The dielectric plates are divided into four areas on the double-layer dielectric substrate, and each area is provided with a resonance unit. The resonance unit comprises a cross-shaped unit, a square-shaped unit and a triangular-shaped unit. The cross-shaped unit is arranged at the center, and four vacancy areas are formed around the cross-shaped unit. Each vacancy area is provided with a square-shaped unit and two triangular-shaped units. The application improves the defects of narrow absorption bandwidth and poor incident angle stability of a conventional two-dimensional dielectric loss type wave-absorbing body structure, enhances the wave-absorbing performance, has a wider absorption bandwidth, more stable polarization and angle insensitivity characteristics, and has a wide application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metamaterial wave absorber structure, and particularly relates to a three-dimensional broadband wave absorber structure capable of enhancing wave absorption performance, which can be applied to radar imaging, satellite communication, 5G communication and electromagnetic radiation suppression of chip system. BACKGROUND

[0002] The metamaterial wave absorber structure is one of important application fields of metamaterials, and its working principle mainly utilizes resonance loss of its own structure to absorb electromagnetic waves, converts electromagnetic energy into heat energy or other forms of energy for dissipation, so as to realize loss of electromagnetic waves. The above properties make the metamaterial wave absorber structure have great application value in the fields of national defense and military, radar communication and the like, and become an important research direction in the field of electromagnetic shielding.

[0003] At present, the metamaterial wave absorber structure can be divided into dielectric loss type wave absorber structure and ohmic loss type wave absorber structure according to different loss mechanisms. The dielectric loss type wave absorber structure usually uses a periodic metal structure printed on a dielectric plate, and adjusts part of parameters according to actual requirements to realize impedance matching, so as to achieve good wave absorption performance. The traditional dielectric loss type wave absorber structure usually refers to a two-dimensional "sandwich" type wave absorber structure, which is composed of three layers of "metal layer-dielectric layer-metal layer". The two-dimensional dielectric loss type wave absorber structure has advantages of high absorption rate and lightness, but also has problems such as narrow absorption bandwidth and sensitive to incident angle. When the wave absorber structure is applied to scenes such as chip packaging, the electromagnetic wave is not ideally vertically incident, and the problems of narrow absorption bandwidth and sensitive to large incident angle of the two-dimensional dielectric loss type wave absorber structure will cause the original wave absorption performance to weaken and the shielding efficiency to decrease. Therefore, improving the angle stability and expanding the absorption bandwidth have become technical problems to be solved in the field of metamaterial wave absorber structure. SUMMARY

[0004] In view of the problems in the above-mentioned existing research contents, the present application provides a three-dimensional broadband wave absorber structure capable of enhancing wave absorption performance, which improves the angle stability and expands the absorption bandwidth.

[0005] The present application is a three-dimensional broadband wave absorber structure for improving overall wave absorption performance. The electromagnetic wave in free space is incident to the resonant unit of the wave absorber structure through impedance matching. Since the bottom layer of the wave absorber structure is covered with a metal back plate, the electromagnetic wave cannot penetrate, so it is all reflected and dissipated multiple times in the wave absorber structure unit, thereby realizing absorption of the electromagnetic wave.

[0006] The technical scheme adopted by the present application to solve the above technical problems is as follows:

[0007] The wave absorber structure comprises a planar part and a vertical part.

[0008] The planar part is mainly composed of a layer of metal back plate, double-layer dielectric substrate and resonant units on the surface of the double-layer dielectric substrate, and the resonant units and the metal back plate are respectively located on the upper and lower surfaces of the double-layer dielectric substrate.

[0009] The vertical part is located directly above the planar part, and the vertical part is composed of a cross-shaped dielectric plate vertically placed and resonant units printed on the surface of the dielectric plate.

[0010] The bottom of the dielectric plate is located on the upper surface of the double-layer dielectric substrate, and the dielectric plate divides the upper surface of the double-layer dielectric substrate into four areas, which are respectively located at the four corners, and one resonant unit is arranged on each area.

[0011] The wave-absorbing body structure is composed of a planar part and a vertical part, wherein the planar part is composed of a surface loss layer, a double-layer dielectric substrate and a single-layer metal back plate; the vertical part is composed of a cross-shaped dielectric plate vertically placed on the planar part and a loss layer printed on the surface of the dielectric plate. The loss layer is composed of multiple groups of resonant units with central symmetry, wherein each group of resonant units includes one cross-shaped cross-shaped unit placed at 45°, four square-shaped square-shaped units placed at 45° and eight inverted triangular-shaped triangular-shaped units.

[0012] The side surface of each branch of the cross-shaped dielectric plate is provided with a resonant unit.

[0013] The resonant unit is a square as a whole, including a cross-shaped cross-shaped unit, four square-shaped square-shaped units and eight isosceles triangular-shaped triangular-shaped units; the cross-shaped cross-shaped unit is placed in the center, two intersecting lines in the cross-shaped cross-shaped unit are arranged along the diagonal lines of the resonant unit, four isosceles triangular-shaped larger hollow areas are formed around the cross-shaped cross-shaped unit, one square-shaped square-shaped unit and two triangular-shaped triangular-shaped units are placed in each larger hollow area, the square-shaped square-shaped unit is placed in the middle of the larger hollow area and close to the center side, two diagonal lines of the square-shaped square-shaped unit and the diagonal lines of the resonant unit are arranged at an angle of 45 degrees, two isosceles triangular-shaped smaller hollow areas exist in the larger hollow area except the area where the square-shaped square-shaped unit is located, one triangular-shaped triangular-shaped unit is placed in each smaller hollow area, and two waists of the triangular-shaped triangular-shaped unit are arranged along the diagonal lines of the resonant unit.

[0014] The cross-shaped cross-shaped unit, the square-shaped square-shaped unit and the triangular-shaped triangular-shaped unit have gaps between each other, and the gaps are equal at different positions.

[0015] The double-layer dielectric substrate is laminated by an upper dielectric substrate layer and a lower dielectric substrate layer.

[0016] All the resonant units located at the planar part are arranged symmetrically along the circumferential direction with respect to the horizontal center point of the planar part, and all the resonant units located at the vertical part are arranged symmetrically in pairs with respect to the vertical center axis.

[0017] The medium plate is made of FR-4 material.

[0018] The upper medium substrate and the lower medium substrate are made of different materials, and are made of FR-4 material and ECCOSORB-BSRU1 material respectively.

[0019] The dielectric constant of the FR-4 material is 4.3, and the loss tangent is 0.025.

[0020] The metal back plate and the resonant unit are both made of copper, and the conductivity is 5.96*10 7 S / m.

[0021] The three-dimensional broadband wave-absorbing body structure has better wave-absorbing performance than the traditional two-dimensional medium loss type wave-absorbing body structure, specifically, a wider absorption bandwidth (7-22GHz) and more stable angle insensitivity (stable absorption bandwidth and high absorption rate when the incident angle is 70°).

[0022] Firstly, the double-layer medium substrate is used to expand the absorption bandwidth; secondly, the vertical structure is introduced to upgrade the wave-absorbing body structure from the traditional two-dimensional mode to the three-dimensional mode, and the vertical structure improves the angle stability of the wave-absorbing body structure; finally, the two are combined, and the three-dimensional broadband wave-absorbing body structure solves the problems of narrow absorption bandwidth and poor angle stability of the traditional two-dimensional medium loss type wave-absorbing body structure.

[0023] In specific implementation, the double-layer medium substrate of the planar part of the three-dimensional broadband wave-absorbing body structure improves the narrow absorption bandwidth of the original two-dimensional medium loss type wave-absorbing body structure; the cross-shaped medium substrate and the multiple groups of resonant units on the surface thereof of the vertical part of the three-dimensional broadband wave-absorbing body structure provide good angle stability for the wave-absorbing body structure, so that the wave-absorbing body structure realizes absorption of electromagnetic waves scattered in various directions.

[0024] In specific implementation, the three-dimensional broadband wave-absorbing body structure realizes an absorption rate of more than 85% in a frequency range of 7-22GHz, and still maintains good wave-absorbing performance when the incident angle reaches 70 degrees, and high absorption rate in the required frequency band can be realized by adjusting part of the parameters of the wave-absorbing body structure, such as the substrate thickness and the medium material.

[0025] The working principle of the wave-absorbing body structure is as follows:

[0026] Electromagnetic wave radiation sources in free space are usually complex in type and large in scattering angle, and the wave-absorbing performance of two-dimensional wave-absorbing body structures is easily affected by the incident angle, resulting in changes in resonant frequency and reduction in absorption rate, and meanwhile, two-dimensional dielectric loss type wave-absorbing body structures also have the defect of narrow absorption bandwidth. In order to solve the problems of large incident angle instability and narrow absorption bandwidth of the above two-dimensional wave-absorbing body structure, the three-dimensional wideband wave-absorbing body structure combining the double-layer substrate, the three-dimensional structure and the traditional two-dimensional structure is pushed out by referring to the design concept of new wave-absorbing body structures such as multilayer wave-absorbing structure, the absorption bandwidth is expanded, and the angle stability of the wave-absorbing structure is improved.

[0027] When electromagnetic waves are incident on the surface of a metal structure, reflection or transmission occurs, and the expressions of reflectivity and transmissivity are R(omega) and T(omega) respectively. 11 | 2 T(omega) = |S 21 | 2 . The absorption rate A(omega) is expressed by the following formula: A(omega) = 1-R(omega)-T(omega) = 1-|S 11 | 2 -|S 21 | 2 . Wherein omega represents the frequency of the incident electromagnetic wave; R(omega) is the reflectivity of the wave-absorbing body, which represents the energy intensity of the incident electromagnetic wave reflected back by the wave-absorbing body; T(omega) is the transmissivity of the wave-absorbing body, which represents the energy intensity of the incident electromagnetic wave transmitted through the wave-absorbing body; S 11 represents the reflection coefficient of the wave-absorbing body; S 21 represents the transmission coefficient of the wave-absorbing body; A(omega) represents the absorption rate of the wave-absorbing body.

[0028] The back plate of the structure of the present application is fully covered with copper, which blocks the transmission of electromagnetic waves, and the transmissivity T(omega) = 0, so that the formula of the absorption rate A(omega) is: A(omega) = 1-R(omega) = 1-|S 11 | 2 . It can be seen from the formula that when the reflectivity is close to 0, the wave-absorbing body of the present application can achieve the maximum absorption efficiency.

[0029] The present application can be applied to radar imaging, satellite communication, 5G communication and electromagnetic radiation suppression of chip system.

[0030] The beneficial effects of the present application are:

[0031] The three-dimensional wideband wave-absorbing body structure of the present application realizes wideband absorption and large-angle working stability of the wave-absorbing body structure by using double-layer dielectric substrates and three-dimensional vertical structures. The present application can realize periodic arrangement of multiple wave-absorbing body structures in a certain space, and the present application is suitable for traditional PCB process for processing and production, and the production cost is controllable.

[0032] The three-dimensional broadband wave-absorbing body structure has the advantages of broadband absorption, polarization insensitivity and stability at large incidence angles, and can realize high wave-absorbing performance in different frequency ranges by adjusting the surface resonance unit structure, dielectric material and thickness of the wave-absorbing body structure, and therefore has a wide range of applications. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a three-dimensional structure diagram of a three-dimensional broadband wave-absorbing body structure unit used in the application;

[0034] Figure 2 is a top view of a three-dimensional broadband wave-absorbing body structure unit structure used in the application;

[0035] Figure 3 is a side view of a three-dimensional broadband wave-absorbing body structure unit structure used in the application;

[0036] Figure 4 is a front view of a resonance unit in a loss layer of a three-dimensional broadband wave-absorbing body structure used in the application;

[0037] Figure 5 is a reflection coefficient result diagram of a three-dimensional broadband wave-absorbing body structure used in the application under different polarization modes

[0038] S11 result diagram;

[0039] Figure 6 is an absorption rate result diagram of a three-dimensional broadband wave-absorbing body structure used in the application under different polarization modes;

[0040] Figure 7 is an absorption rate result diagram of a three-dimensional broadband wave-absorbing body structure used in the application under different incidence angles.

[0041] In the figure: medium plate 1, resonance unit 2, upper layer medium substrate 3, lower layer medium substrate 4, metal back plate 5. DETAILED DESCRIPTION

[0042] The application will be further described below with reference to the accompanying drawings.

[0043] The purpose of the application is to provide a new type of metamaterial wave-absorbing body structure, which solves the problems of narrow absorption bandwidth and angle sensitivity of traditional two-dimensional wave-absorbing body structures to some extent.

[0044] As shown in Figure 1 , the wave-absorbing body structure comprises a planar part and a vertical part;

[0045] The planar part is a square, and the planar part mainly comprises a layer of metal back plate 5, double-layer medium substrate and resonance unit 2 on the surface of the double-layer medium substrate, and the resonance unit 2 and the metal back plate 5 are respectively located on the upper and lower surfaces of the double-layer medium substrate;

[0046] The vertical part is located directly above the planar part, and is composed of a medium plate 1 arranged vertically in a cross shape and a resonant unit 2 printed on the surface of the medium plate 1, the medium plate 1 being arranged perpendicularly to the double-layer medium substrate 5.

[0047] As shown in Figure 2 , the bottom of the medium plate 1 is located on the upper surface of the double-layer medium substrate, the side length of the medium plate 1 is aligned with the side length of the double-layer medium substrate, and the medium plate 1 divides the upper surface of the double-layer medium substrate into four areas, each of which is located at a corner and has one resonant unit 2 arranged thereon, and the resonant unit 2 is arranged at the center of the area.

[0048] The main side of each branch of the medium plate 1 in the cross shape can be a square, and each branch is provided with one resonant unit 2 arranged at the center of the side.

[0049] The resonant unit 2 serves as a surface loss layer, and all resonant units 2 have the same pattern and have central symmetry. Whether in the vertical part or the planar part, the surface loss layer is located on the surface of the medium layer and is composed of multiple groups of resonant units 2 with the same pattern.

[0050] As shown in Figure 4 , the resonant unit 2 as a whole is a square, including a cross-shaped cross unit, four square-shaped square units and eight isosceles triangular triangular units; the cross unit is placed in the center, and the two intersecting lines in the cross unit are arranged along the diagonals of the resonant unit 2; four larger isosceles triangular void areas are formed around the cross unit in the circumferential direction, one square unit and two triangular units are placed in each larger void area, the square unit is placed in the middle of the larger void area and close to the center side, the two diagonals of the square unit are arranged at an angle of 45 degrees with the diagonals of the resonant unit 2, and two smaller isosceles triangular void areas are formed in the larger void area except the area where the square unit is located, one triangular unit is placed in each smaller void area, and the two waists of the triangular unit are arranged along the diagonals of the resonant unit 2.

[0051] The adjacent edges of the cross unit and the square unit, the adjacent edges of the square unit and the triangular unit, and the adjacent edges of the cross unit and the triangular unit are arranged in parallel at intervals. In this way, the cross unit, the square unit and the triangular unit have gaps between each other, and the gaps are equal at different positions.

[0052] The surface resonant units in the planar part and the surface resonant units in the vertical part have the same pattern, and the gaps between the cross units, the square units and the triangular units of each group of resonant units are equal in size.

[0053] AsFigure 1 and Figure 3 As shown, the double-layer dielectric substrate is formed by stacking an upper dielectric substrate 3 and a lower dielectric substrate 4 located on the upper and lower layers respectively. The upper dielectric substrate 3 and the lower dielectric substrate 4 have the same shape and structure and are arranged in an overlapping manner.

[0054] All resonant units 2 located in the planar part are symmetrically arranged with respect to the horizontal center point of the planar part along the circumference, and all resonant units 2 located in the vertical part are arranged symmetrically in pairs with respect to the vertical central axis.

[0055] The planar portion has four resonant units, which are symmetrically arranged around the horizontal center point of the planar portion at even intervals along the circumference. The vertical portion has eight resonant units, which are symmetrically arranged in pairs around the vertical central axis. The metal backplate 5 is completely attached to the underside of the lower dielectric substrate 4, and its shape and area are the same as those of the lower dielectric substrate 4.

[0056] The loss layer and metal backplate of the three-dimensional broadband absorber structure are both made of copper, with a conductivity of 5.96 × 10⁻⁶. 7 The dielectric constant is S / m, and the thickness is 0.017 mm. The planar portion of the double-layer dielectric substrate consists of ECCOSORB-BSRU1 material and FR-4 material from bottom to top, while the cross-shaped dielectric substrate in the vertical portion is made of FR-4 material. The FR-4 material has a dielectric constant of 4.3 and a loss tangent of 0.025.

[0057] like Figure 2 As shown in the front view of the three-dimensional broadband absorber structure, the length of the planar substrate of the absorber structure is l, and the thickness of the vertical cross substrate is l1. The specific dimensional parameters are shown in Table 1.

[0058] like Figure 3 As shown in the side view of the three-dimensional broadband absorber structure, the thicknesses of the double-layer planar substrates of the absorber structure are h1 and h2, respectively, and the height of the vertical cross substrate is h. The specific dimensional parameters are shown in Table 1.

[0059] like Figure 4 As shown, the main view of the resonant unit of the loss layer of the three-dimensional broadband absorber structure is given, and the specific dimensional parameters are shown in Table 1.

[0060] Figure 5 and Figure 6 The figures show the reflection coefficient and absorption rate of the present invention under different polarization modes. The results show that the three-dimensional broadband absorber structure can achieve an absorption rate of more than 85% in the frequency range of 7-22 GHz in both TE and TM modes, and has the characteristic of being polarization insensitive.

[0061] like Figure 7As shown, the absorptivity curves of the three-dimensional broadband absorber structure under different incident angles of electromagnetic waves are presented. The results show that the absorber structure maintains good absorption performance in the range of 0°-70°. With the increase of the incident angle, the absorption bandwidth of the absorber structure shifts to the right and broadens to some extent, but the overall operating frequency band remains stable and the absorption performance is good. Therefore, the absorber structure has a stable incident angle insensitivity characteristic.

[0062] The detailed dimensions of this invention are shown in Table 1. In practical applications, the resonant unit, dielectric substrate material, and thickness can be adjusted according to the specific required operating frequency band to obtain the corresponding wave absorption effect.

[0063] Table 1 Dimensions of each part of the three-dimensional broadband absorber structure of the present invention

[0064] l ​ [l2] [l3] [l4] 6 mm 0.5 mm 3 mm 0.85 mm 0.25 mm h [CDATA[h2]]> [ h2 ] d 2.75 mm 0.5 mm 0.6 mm 0.1 mm

[0065] Compared to traditional two-dimensional dielectric loss absorber structures, this invention innovatively introduces the design of a vertical absorbing structure, combining it with the traditional two-dimensional absorbing structure to obtain the three-dimensional broadband absorber structure of this invention. The three-dimensional broadband absorber structure improves upon the shortcomings of traditional two-dimensional absorber structures, such as narrow absorption bandwidth and poor incident angle stability. Figure 6 , Figure 7 As shown, the absorption performance remains stable within the range of 0-70°, achieving absorption stability under large angle incidence.

[0066] Therefore, this invention realizes a three-dimensional absorbing structure design that enhances the absorbing performance compared to the traditional two-dimensional dielectric loss type absorbing body structure.

[0067] The three-dimensional broadband absorber structure of the present invention improves the shortcomings of traditional two-dimensional dielectric loss absorber structures, such as narrow absorption bandwidth and poor incident angle stability, enhances absorption performance, and has a wider absorption bandwidth as well as more stable polarization and angle insensitivity characteristics. It has important application prospects in radar imaging, satellite communication and radiation suppression of chip systems.

Claims

1. A three-dimensional broadband wave-absorbing structure with enhanced wave-absorbing performance, characterized in that: the wave-absorbing structure comprises a planar part and a vertical part; the planar part is mainly composed of a metal back plate (5), a double-layer dielectric substrate, and resonant units (2) on the surface of the double-layer dielectric substrate, with the resonant units (2) and the metal back plate (5) respectively located on the upper and lower surfaces of the double-layer dielectric substrate; the vertical part is located directly above the planar part and is composed of a dielectric plate (1) vertically placed in a cross shape and resonant units (2) printed on the surface of the dielectric plate (1); the resonant units (2) are square in shape as a whole and comprise a cross-shaped cross unit, four square-shaped square units, and eight isosceles triangular triangular units; the cross unit is placed in the center, with the two intersecting lines in the cross unit arranged along the diagonals of the resonant units (2), and four larger hollow areas in the shape of isosceles triangles are formed around the cross unit, with a square unit and two triangular units placed in each larger hollow area, the square unit being placed in the middle of the larger hollow area and arranged close to the center side, the two diagonals of the square unit being arranged at an angle of 45 degrees with the diagonals of the resonant units (2), and two smaller hollow areas in the shape of isosceles triangles being formed in the larger hollow area except for the area where the square unit is located, with a triangular unit placed in each smaller hollow area, the two waists of the triangular unit being arranged along the diagonals of the resonant units (2); the cross unit, the square unit, and the triangular unit all have gaps between each other, and the gaps are equal in size. The bottom of the dielectric plate (1) is located on the upper surface of the double-layer dielectric substrate, and the dielectric plate (1) divides the upper surface of the double-layer dielectric substrate into four areas, with one resonant unit (2) arranged in each area. Each side of each branch of the dielectric plate (1) in the cross shape is provided with a resonant unit (2). The double-layer dielectric substrate is composed of an upper dielectric substrate (3) and a lower dielectric substrate (4) stacked one above the other. All resonant units (2) in the planar part are arranged symmetrically along the circumference with respect to the horizontal center point of the planar part, and all resonant units (2) in the vertical part are arranged symmetrically in pairs with respect to the vertical center axis. The dielectric plate (1) is made of FR-4 material.

2. The three-dimensional wideband wave-absorbing structure with enhanced wave-absorbing performance according to claim 1, characterized in that: The upper dielectric substrate (3) and the lower dielectric substrate (4) are made of different materials, with the upper dielectric substrate (3) made of FR-4 material and the lower dielectric substrate (4) made of ECCOSORB-BSRU1 material. 3.The three-dimensional wideband wave-absorbing structure with enhanced wave-absorbing performance of claim 1, wherein: The structure is applied to electromagnetic radiation suppression in radar imaging, satellite communication, 5G communication, and chip systems.

4. The three-dimensional wideband wave-absorbing structure with enhanced wave-absorbing performance according to claim 1, characterized in that: ​ 5. The three-dimensional wideband wave-absorbing structure with enhanced wave-absorbing performance according to claim 1, characterized in that: ​ 6. The three-dimensional wideband wave-absorbing structure with enhanced wave-absorbing performance according to claim 1, characterized in that: ​ 7. The three-dimensional wideband wave-absorbing structure with enhanced wave-absorbing performance according to claim 4, characterized in that: ​ 8. The use of a three-dimensional wideband wave-absorbing structure according to any one of claims 1-7, characterized in that: ​

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