Ultra-wideband three-dimensional metamaterial wave absorber with large angular domain stability

Abstract

The invention discloses an ultra-wideband three-dimensional metamaterial wave absorber with large angular domain stability, which comprises M * N wave absorber units, and is characterized in that M is more than or equal to 10 rows, N is more than or equal to 10 columns, and each wave absorber unit sequentially comprises an upper-layer three-dimensional vertical resistive film patch cylindrical structure, a bottom square resistive film structure or a metal bottom plate II from top to bottom, a lower-layer three-dimensional vertical resistive film patch cylindrical structure and a lower-layer square resistive film patch cylindrical structure from top to bottom. And the cylindrical structure of the upper-layer three-dimensional vertical resistive film patch is adhered to the bottom square resistive film structure through optical cement or adhered to the metal bottom plate II. According to the invention, the effects of ultra-wide absorption bandwidth, large angular domain stability and polarization insensitivity can be realized.

Description

Technical Field

[0001] This invention belongs to the field of metamaterial absorber technology, specifically referring to an ultra-wideband three-dimensional metamaterial absorber with large angular domain stability. Background Technology

[0002] With the development of advanced detectors and precision guidance technologies, electromagnetic absorbing devices (EMDs) play a crucial role in both civilian and military fields. In stealth technology, EMDs are widely used in stealth aircraft, ships, and ground vehicles to reduce their radar cross-section, enhance military mobility, and decrease the likelihood of detection by the enemy. In communications, EMDs reduce signal leakage from communication equipment, improve communication security, and reduce the risk of being eavesdropped on and jammed by the enemy. In radar systems, EMDs improve radar performance and reduce the likelihood of interference from enemy electronic warfare methods. Furthermore, EMDs play a vital role in electronic warfare systems and missile technology, weakening enemy system performance and reducing the likelihood of missile detection. These applications highlight the strategic value of EMDs in military strategy, playing a key role in improving combat effectiveness, ensuring communication security, and maintaining military secrecy.

[0003] To meet the demands of modern stealth technology, one of the most effective methods is to utilize absorbers capable of absorbing broadband and wide-angle electromagnetic waves. On one hand, current research data shows that traditional absorbing metamaterials (such as multilayer impedance-gradient structures and ferrite composites) can achieve energy absorption efficiencies of over 80% in the mid-to-high frequency band (e.g., 2-18 GHz) through optimized design, and their broadband performance has been verified in radar stealth and electromagnetic shielding scenarios. However, limited by the material's inherent frequency response characteristics and structural coupling mechanisms, the effective absorption bandwidth of these absorbers (defined as the frequency range with reflectivity ≤ -10 dB) is typically difficult to exceed the 20 GHz limit. This restricts their application in multi-band compatible electronic devices and broadband stealth technology. On the other hand, regarding adaptability to electromagnetic wave incident angles, when the incident angle exceeds 30° (e.g., in scenarios where an aircraft is side-illuminated by radar), the reflectivity attenuation of traditional absorbers deteriorates sharply from -30 dB at vertical incidence to below -8 dB (taking the Ku band as an example). These shortcomings directly hinder their engineering deployment in scenarios such as wide-angle scanning phased array radar (requiring coverage of ±60° incident angle) and stealth on curved carriers (such as the conical nose of a missile). Therefore, existing absorbing metamaterials are large in size and weight, have a small angular coverage range, and have not yet been widely used in certain application areas. Furthermore, they cannot simultaneously address the issues of large-angle stability, ultra-wideband absorption, and polarization insensitivity. Summary of the Invention

[0004] The purpose of this invention is to provide an ultra-wideband three-dimensional metamaterial absorber with large-angle stability, which can simultaneously address the issues of large-angle stability, ultra-wideband absorption, and polarization insensitivity.

[0005] This invention discloses a wide-angle stable ultra-wideband metamaterial absorber, comprising M×N absorber units, where M ≥ 10 rows and N ≥ 10 columns. Each absorber unit comprises, from top to bottom, an upper three-dimensional vertical resistive film patch cylindrical structure, a bottom square resistive film structure, or a metal base plate II. The upper three-dimensional vertical resistive film patch cylindrical structure is bonded to the bottom square resistive film structure by optical adhesive, or bonded to the metal base plate II.

[0006] As a further embodiment of the present invention: the cylindrical structure of the upper three-dimensional vertical resistive film patch consists of a coaxial cylindrical foam layer, a cylindrical dielectric substrate layer, and a cylindrical resistive film layer from the inside out. The cylindrical resistive film layer is printed on the cylindrical dielectric substrate layer, and optical adhesive is used to bond the cylindrical dielectric substrate layer and the cylindrical foam layer. The cylindrical foam layer plays a supporting role.

[0007] The bottom square resistive film structure consists of, from top to bottom, a square resistive film layer, a square dielectric substrate layer, a square dielectric base plate layer, and a metal base plate I. The square resistive film layer is printed on the square dielectric substrate layer, and the square dielectric substrate layer and the square dielectric base plate layer are bonded together using optical adhesive.

[0008] As a further aspect of the present invention: the horizontal plane of the bottom square resistive film structure or metal base plate II is square.

[0009] As a further aspect of the present invention: the cylindrical foam layer, the cylindrical dielectric substrate layer, and the cylindrical resistive film layer have the same height; the center of the cylindrical foam layer coincides with the center of the bottom square resistive film structure, or the center of the cylindrical foam layer coincides with the center of the metal base plate II.

[0010] As a further aspect of the present invention: the diameter of the cylindrical resistive film layer is smaller than the side length of the square resistive film layer, or the diameter of the cylindrical resistive film layer is smaller than the side length of the metal base plate II.

[0011] As a further aspect of the present invention: the side length of the square resistive film layer is equal to the side length of the square dielectric substrate layer, the side length of the square dielectric substrate layer is equal to the side length of the metal base plate I, and the side length of the square resistive film layer is less than the side length of the square dielectric substrate layer.

[0012] As a further embodiment of the present invention: the diameter d of the cylindrical foam layer is 7 mm and the height h1 is 21 mm; the thickness th1 of the cylindrical dielectric substrate layer is 0.175 mm; the side length w1 of the square resistive film layer is 15 mm and the thickness th2 of the square dielectric substrate layer is 0.175 mm; the side length p1 of the square dielectric substrate layer is 16 mm and the thickness th3 is 1 mm; and the thickness of the metal base plate I is 0.018 mm.

[0013] As a further aspect of the present invention: the side length p3 of the metal base plate II is 16mm, and the thickness of the metal base plate II is 0.018mm.

[0014] As a further embodiment of the present invention: the cylindrical foam layer is made of polymethacrylamide foam with a dielectric constant of 1.05 and a loss of 0.001; the cylindrical dielectric substrate layer is made of polyethylene terephthalate with a dielectric constant of 3 and a loss of 0.061; the square dielectric substrate layer is made of polyethylene terephthalate with a dielectric constant of 3 and a loss of 0.061; and the square dielectric substrate layer is made of TLY-5 with a dielectric constant of 2.2 and a loss of 0.0009.

[0015] Both the cylindrical and square resistive film layers use resistive films with a sheet resistance of 300Ω / sq.

[0016] As a further aspect of the present invention: the thickness of the optical adhesive is 0.01 mm, and its impact on the performance of the metamaterial absorber is negligible.

[0017] Compared with the prior art, the present invention provides two types of absorbing unit structures: one is an absorbing unit composed of a cylindrical structure of a vertical resistive film patch and a metal base plate, and the other is an absorbing unit composed of a cylindrical structure of a vertical resistive film patch and a square resistive film structure at the bottom. Ultra-wideband performance is achieved through the dynamic complementarity of the vertical cylindrical structure and the square resistive film structure of the absorbing unit, and large-angle stability is achieved through the electromagnetic resonance of the cylindrical resistive film layer. Both structures can achieve ultra-wide absorption bandwidth, large-angle stability, and polarization insensitivity. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the absorber unit composed of the cylindrical structure of the vertical resistive film patch and the square resistive film structure at the bottom of the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of the absorber unit composed of the cylindrical structure of the vertical resistive film patch and the metal base plate of the present invention.

[0020] Figure 3 This is a schematic diagram of the bottom square resistive film structure in this invention.

[0021] Figure 4 This is a diagram showing the reflection coefficient and absorptivity of the cylindrical structure in Embodiment 1 of the present invention when incident perpendicularly.

[0022] Figure 5 This is an absorption rate diagram of the upper vertical cylindrical structure of Embodiment 1 of the present invention under TE polarization when obliquely incident.

[0023] Figure 6 This is an absorption rate diagram of the upper vertical cylindrical structure of Embodiment 1 of the present invention under TM polarization when obliquely incident.

[0024] Figure 7 This is a reflection coefficient diagram for vertical incidence in Embodiment 2 of the present invention.

[0025] Figure 8 This is the absorption rate diagram of the structure of Embodiment 2 of the present invention under TE polarization when incident obliquely.

[0026] Figure 9 This is the absorption rate diagram of the structure of Embodiment 2 of the present invention under TM polarization when obliquely incident.

[0027] In the figure: 1. Cylindrical foam layer, 2. Cylindrical dielectric substrate layer, 3. Cylindrical resistive film layer, 4. Square resistive film layer, 5. Square dielectric substrate layer, 6. Square dielectric substrate layer, 7. Metal base plate I, 8. Metal base plate II. Detailed Implementation

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] A large-angle-domain stable ultrawideband three-dimensional metamaterial absorber comprises M×N absorber units, where M ≥ 10 rows and N ≥ 10 columns; as shown... Figures 1 to 2 As shown, each absorber unit comprises, from top to bottom, a cylindrical structure of an upper three-dimensional vertical resistive film patch, a bottom square resistive film structure or a metal base plate II8; the bottom square resistive film structure consists of, from top to bottom, a square resistive film layer 4, a square dielectric substrate layer 5, a square dielectric substrate layer 6, and a metal base plate I7. The cylindrical structure of the upper three-dimensional vertical resistive film patch can simultaneously generate electric and magnetic resonance under the excitation of incident electromagnetic waves. As the incident angle increases, the component of the magnetic field on the cylinder gradually increases, thus increasing the intensity of the magnetic resonance. However, the electric field remains perpendicular to the upper plane of the cylinder, enabling the excitation of electric resonance. Simultaneously, the multiple standing wave reflections brought about by the bottom square resistive film structure or the metal base plate II8 further expand the absorption bandwidth and increase the absorption intensity. Therefore, the cylindrical structure of the upper vertical resistive film patch possesses large-angle stability and broadband performance. Finally, the bottom square resistive film structure or the metal base plate further broadens the absorber bandwidth.

[0030] The cylindrical structure of the upper three-dimensional vertical resistive film patch consists of, from the inside out, a coaxial cylindrical foam layer 1, a cylindrical dielectric substrate layer 2, and a cylindrical resistive film layer 3. The cylindrical resistive film layer 3 is printed on the cylindrical dielectric substrate layer 2. The cylindrical dielectric substrate layer 2 and the cylindrical foam layer 1 are bonded together using optical adhesive. The thickness of the optical adhesive is 0.01 mm, which has a negligible impact on the performance of the metamaterial absorber. The cylindrical foam layer 1 serves as a support.

[0031] The bottom square resistive film structure or the horizontal plane of the metal base plate II is square.

[0032] The cylindrical foam layer 1, the cylindrical dielectric substrate layer 2, and the cylindrical resistive film layer 3 have the same height. The center of the cylindrical foam layer 1 coincides with the center of the bottom square resistive film structure, or the center of the cylindrical foam layer 1 coincides with the center of the metal base plate II8.

[0033] The diameter of the cylindrical resistive film layer 3 is smaller than the side length of the square resistive film layer 4, or the diameter of the cylindrical resistive film layer 3 is smaller than the side length of the metal base plate II8.

[0034] like Figure 3 As shown, the square resistive film layer 4 is printed on the square dielectric substrate layer 5. Optical adhesive is used to bond the square dielectric substrate layer 5 and the square dielectric base layer 6. The thickness of the optical adhesive bonding is 0.01 mm, and its impact on the performance of the metamaterial absorber is negligible. The side length of the square resistive film layer 4 is equal to the side length of the square dielectric substrate layer 5, and the side length of the square dielectric base layer 6 is equal to the side length of the metal substrate I7. The side length of the square resistive film layer 4 is less than the side length of the square dielectric base layer 6.

[0035] The cylindrical structure of the upper three-dimensional vertical resistive film patch and the square resistive film structure at the bottom are bonded together using optical adhesive. The thickness of the optical adhesive is 0.01 mm, and its impact on the performance of the metamaterial absorber is negligible.

[0036] The cylindrical structure of the upper three-dimensional vertical resistive film patch and the metal base plate II8 are bonded together using optical adhesive. The thickness of the optical adhesive is 0.01 mm, and its impact on the performance of the metamaterial absorber is negligible.

[0037] The cylindrical foam layer 1 has a diameter d of 7 mm and a height h1 of 21 mm; the cylindrical dielectric substrate layer 2 has a thickness th1 of 0.175 mm, and the cylindrical resistive film 3 is coated on the cylindrical dielectric substrate layer 2.

[0038] A square resistive film layer 4 covers a square dielectric substrate layer 5. The side length w1 of the square resistive film layer 4 is 15 mm and the thickness th2 is 0.175 mm. The side length p1 of the square dielectric substrate layer 6 is 16 mm and the thickness th3 is 1 mm. The side length p2 of the bottom metal base plate I7 ​​is 16 mm and the thickness of the metal base plate I7 ​​is 0.018 mm.

[0039] The side length p3 of the metal base plate II8 is 16mm, and the thickness of the metal base plate II8 is 0.018mm.

[0040] The cylindrical foam layer 1 is made of polymethacrylamide foam (PMI) with a dielectric constant of 1.05 and a loss of 0.001; the cylindrical dielectric substrate layer 2 is made of polyethylene terephthalate (PET) with a dielectric constant of 3 and a loss of 0.061; the square dielectric substrate layer 5 is made of polyethylene terephthalate (PET) with a dielectric constant of 3 and a loss of 0.061; and the square dielectric substrate layer 6 is made of TLY-5 with a dielectric constant of 2.2 and a loss of 0.0009.

[0041] Both the cylindrical resistive film layer 3 and the square resistive film layer 4 use resistive films with a sheet resistance of 300Ω / sq.

[0042] Metal base plate I7 ​​and metal base plate II8 are both high conductivity metal characteristic plates. In this embodiment, metal base plate I7 ​​and metal base plate II8 are both copper metal, M=19, N=19.

[0043] In Example 1, for a cylindrical structure with a metal base plate II8 and an upper three-dimensional vertical resistive film patch as the absorber unit, electromagnetic waves are incident perpendicularly on the surface of this structure. The electric field is along the x-axis, and the magnetic field is along the y-axis. Due to the presence of the metal base plate II8, each cylindrical structure unit can be considered as a vertical short-circuit transmission line. According to microwave transmission line theory, the response of a short-circuit transmission line to electromagnetic waves at odd multiples of wavelength can be equivalent to an LC parallel circuit, i.e., LC resonance occurs at odd multiples of the length of the short-circuit transmission line. When the cylinder height is an odd multiple of a quarter wavelength in the filling medium, electromagnetic resonance occurs. When resonance occurs, the local electric field is significantly amplified, thus the incident wave will be consumed if the material has losses. The use of a three-dimensional structure can achieve broadband absorption performance without the need for multiple layers. However, the final broadband strong absorption performance still requires the introduction of a metal substrate II8. This is because the introduction of the metal substrate II8 enables the structure to generate multiple standing waves, which are continuously dissipated within the loss structure formed by the resistive film. As a result, the cylindrical structure of the upper three-dimensional vertical resistive film patch achieves an absorption rate of over 90% in the frequency range of 2.1 GHz to 27.1 GHz. Figure 4 As shown.

[0044] like Figure 5 , 6As shown, for the cylindrical structure of the upper three-dimensional vertical resistive film patch, when electromagnetic waves are obliquely incident on the surface of the structure, under TE polarization, the structure maintains an absorption performance of over 70% up to 70°. Under TM polarization, the structure maintains an absorption performance of over 80% up to 70°. The insensitivity of the absorption performance of the structure of this invention to the incident angle is mainly attributed to the design of the selected three-dimensional structural unit. When a beam of TE wave is incident, its magnetic field H component is perpendicular to the cylindrical plane, so both electric resonance and magnetic resonance can be excited simultaneously. As the incident angle increases, the component of H on the cylinder gradually increases, resulting in an increase in the intensity of magnetic resonance. However, the electric field E remains perpendicular to the upper plane of the cylinder, enabling the excitation of electric resonance. For planar metamaterials, since magnetic resonance cannot be excited, as the incident angle increases, the component of H parallel to the structural unit decreases, leading to a weakening of the magnetic resonance intensity and thus a deterioration in absorption performance. Therefore, three-dimensional metamaterials can maintain a wide and strong absorption performance over a wide range of incident angles.

[0045] In Example 2, to further broaden the bandwidth of the metamaterial absorber, a bottom square resistive film structure was added to the cylindrical structure of the upper three-dimensional vertical resistive film patch to form a metamaterial absorber. The bottom square resistive film structure can broaden the bandwidth. The ultra-wideband three-dimensional metamaterial absorber with large-angle stability provided by this invention has an ultra-wide low-reflection band with a -10dB fractional bandwidth of 189% in the 2-68GHz range, while maintaining large-angle stability of over 70° under TE and TM polarization. Figure 7-9 As shown.

[0046] This invention uses a combination of a vertical cylindrical structure and a square metal base plate or a square resistive film structure to form a metamaterial absorber unit. This symmetrical structure makes the absorber insensitive to polarization.

[0047] This invention addresses the problems of large-angle instability, narrow absorption bandwidth, and oblique incidence sensitivity in existing metamaterial absorbers. It achieves an ultra-wide absorption bandwidth, large-angle stability, polarization insensitivity, and lower cost by combining a vertical cylindrical structure with a bottom resistive film structure or metal plate structure. The ultra-wideband performance is achieved through the dynamic complementarity of the absorber's three-dimensional and two-dimensional structures, and large-angle stability is achieved through the electromagnetic resonance of the three-dimensional resistive film patch cylindrical structure. For practical applications, this large-angle stable ultra-wideband absorber has broader application value, paving the way for practical applications in sensing, imaging, and stealth technologies. Furthermore, the structure proposed in this invention can be extended to the terahertz, infrared, and optical regions.

[0048] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A wide-angle domain stable ultra-wideband three-dimensional metamaterial absorber, comprising M×N absorber units, characterized in that, M≧10 rows, N≧10 columns, the absorber unit includes, from top to bottom, a cylindrical structure of an upper three-dimensional vertical resistive film patch, a square resistive film structure at the bottom, or a metal base plate II (8). The cylindrical structure of the upper three-dimensional vertical resistive film patch is bonded to the square resistive film structure at the bottom by optical adhesive, or bonded to the metal base plate II (8).

2. The ultrawideband three-dimensional metamaterial absorber with large-angle domain stability according to claim 1, characterized in that, The cylindrical structure of the upper three-dimensional vertical resistive film patch consists of a coaxial cylindrical foam layer (1), a cylindrical dielectric substrate layer (2), and a cylindrical resistive film layer (3) from the inside out. The cylindrical resistive film layer (3) is printed on the cylindrical dielectric substrate layer (2), and the cylindrical dielectric substrate layer (2) and the cylindrical foam layer (1) are bonded together using optical adhesive. The cylindrical foam layer (1) serves as a support. The bottom square resistive film structure consists of a square resistive film layer (4), a square dielectric substrate layer (5), a square dielectric substrate layer (6), and a metal base plate I (7) from top to bottom. The square resistive film layer (4) is printed on the square dielectric substrate layer (5), and the square dielectric substrate layer (5) and the square dielectric substrate layer (6) are bonded together using optical adhesive.

3. The ultrawideband three-dimensional metamaterial absorber with large-angle domain stability according to claim 1, characterized in that, The horizontal plane of the bottom square resistive film structure or metal base plate II (8) is square.

4. The ultrawideband three-dimensional metamaterial absorber with large-angle domain stability according to claim 2, characterized in that, The cylindrical foam layer (1), cylindrical dielectric substrate layer (2), and cylindrical resistive film layer (3) have the same height; the center of the cylindrical foam layer (1) coincides with the center of the bottom square resistive film structure, or the center of the cylindrical foam layer (1) coincides with the center of the metal base plate II (8).

5. The ultrawideband three-dimensional metamaterial absorber with large-angle domain stability according to claim 2, characterized in that, The diameter of the cylindrical resistive film layer (3) is smaller than the side length of the square resistive film layer (4), or the diameter of the cylindrical resistive film layer (3) is smaller than the side length of the metal base plate II (8).

6. The ultrawideband three-dimensional metamaterial absorber with large-angle domain stability according to claim 2, characterized in that, The side length of the square resistive film layer (4) is equal to the side length of the square dielectric substrate layer (5), the side length of the square dielectric substrate layer (6) is equal to the side length of the metal base plate I (7), and the side length of the square resistive film layer (4) is less than the side length of the square dielectric substrate layer (6).

7. The ultrawideband three-dimensional metamaterial absorber with large-angle domain stability according to claim 2, characterized in that, The cylindrical foam layer (1) has a diameter d of 7 mm and a height h1 of 21 mm; the cylindrical dielectric substrate layer (2) has a thickness th1 of 0.175 mm; the square resistive film layer (4) has a side length w1 of 15 mm; the square dielectric substrate layer (5) has a thickness th2 of 0.175 mm; the square dielectric substrate layer (6) has a side length p1 of 16 mm and a thickness th3 of 1 mm; and the metal base plate I (7) has a thickness of 0.018 mm.

8. The ultrawideband metamaterial absorber with large-angle domain stability according to claim 1, characterized in that, The side length p3 of the metal base plate II (8) is 16 mm, and the thickness of the metal base plate II (8) is 0.018 mm.

9. The ultrawideband three-dimensional metamaterial absorber with large-angle domain stability according to claim 7, characterized in that, The cylindrical foam layer (1) is made of polymethacrylamide foam with a dielectric constant of 1.05 and a loss of 0.001; the cylindrical dielectric substrate layer (2) is made of polyethylene terephthalate with a dielectric constant of 3 and a loss of 0.061; the square dielectric substrate layer (5) is made of polyethylene terephthalate with a dielectric constant of 3 and a loss of 0.061; and the square dielectric substrate layer (6) is made of TLY-5 with a dielectric constant of 2.2 and a loss of 0.0009. Both the cylindrical resistive film layer (3) and the square resistive film layer (4) use resistive films with a sheet resistance of 300Ω / sq.

10. A large-angle domain stable ultrawideband three-dimensional metamaterial absorber according to claim 1 or 2, characterized in that, The thickness of the optical adhesive bonding is 0.01 mm, and its impact on the performance of the metamaterial absorber is negligible.

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