A three-dimensional wave-absorbing metamaterial, unit structure, preparation method and device

Abstract

This invention discloses an ultrawideband thin-film three-dimensional absorbing metamaterial, comprising a first three-dimensional metastructure, a resistive frequency selective surface, and a second three-dimensional metastructure sequentially coupled together. The first three-dimensional metastructure has stepped bosses and is coupled to the resistive frequency selective surface via the boss surfaces in an inverted step configuration. The second three-dimensional metastructure has a tower-shaped central pillar, and its top surface is coupled to the resistive frequency selective surface. A first resistive film is disposed on the surface of the first three-dimensional metastructure. A ninth resistive film is disposed on the surface of the second three-dimensional metastructure. A metasurface is also disposed on the surface of the second three-dimensional metastructure. The resistive frequency selective surface includes a substrate and a first structural unit formed on the substrate.

Description

Technical Field

[0001] This disclosure belongs to the field of electromagnetic wave absorption technology, and relates to a three-dimensional wave-absorbing metamaterial, unit structure, preparation method and equipment, specifically to an ultra-wideband thin-layer wave-absorbing metamaterial and its unit structure based on a three-dimensional metastructure loaded with a two-dimensional metasurface. Background Technology

[0002] The continuous development of electronic information technology has brought about a series of problems related to electromagnetic radiation and electromagnetic pollution. Electromagnetic shielding technology for electronic devices and components, and electromagnetic protection technology for human health are current research priorities. Compared to electromagnetic shielding technology based on the principle of reflection, electromagnetic absorption technology, which eliminates harmful electromagnetic energy through the loss of electromagnetic energy, is currently the ideal electromagnetic protection technology approach.

[0003] Traditional absorbing coatings are limited by their impedance mismatch as thickness increases, resulting in narrow absorption bandwidths and high areal density at corresponding thicknesses. Circuit-simulated absorbing structures based on resistive loading or resistive films represent ultra-wideband electromagnetic absorbing technology, achieving relatively ideal absorption performance at thinner thicknesses, but suffer from the problem of large absorption thicknesses at low frequencies. Electromagnetic metasurfaces based on pure metallic structural units, as a novel electromagnetic absorbing technology, can achieve absorption peaks at any frequency band at very thin thicknesses, but the absorption bandwidth is extremely narrow. Therefore, the development of novel electromagnetic absorbing materials with thin layers, low areal density, multiple absorption bands, ultra-wideband absorption performance, and good oblique incidence stability is an urgent need. Summary of the Invention

[0004] One embodiment of this disclosure discloses an ultrawideband thin-film three-dimensional absorbing metamaterial, comprising a first three-dimensional metastructure, a resistive frequency-selective surface, and a second three-dimensional metastructure sequentially combined, wherein...

[0005] The first three-dimensional superstructure has a stepped boss, and is connected to the resistive frequency selection surface through the boss surface in an inverted step manner;

[0006] The second three-dimensional superstructure has a tower-shaped central column, and the top surface of the central column is combined with the resistive frequency selection surface.

[0007] The first three-dimensional superstructure surface is provided with a first resistive film. The second three-dimensional superstructure surface is provided with a ninth resistive film. The second three-dimensional superstructure surface is also provided with a metasurface.

[0008] The resistive frequency selective surface includes a substrate and a first structural unit formed on the substrate. Attached Figure Description

[0009] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which:

[0010] Figure 1 A schematic diagram of an ultrawideband thin-layer three-dimensional absorbing metamaterial structure unit according to one embodiment of the present disclosure.

[0011] Figure 2 A schematic diagram of an ultra-wideband thin-layer three-dimensional absorbing metamaterial structure unit according to one embodiment of the present disclosure, wherein: (a) is a schematic diagram of the first three-dimensional metastructure, and (b) is a schematic diagram of the position and geometry of the loaded resistive film.

[0012] Figure 3 A schematic diagram of an ultra-wideband thin-layer three-dimensional absorbing metamaterial structure unit according to one embodiment of the present disclosure, wherein: (a) a schematic diagram of the second three-dimensional metastructure, (b) a schematic diagram of the position and geometry of the loaded resistive film, and (c) a schematic diagram of the position and geometry of the loaded metasurface metal structure unit.

[0013] Figure 4 A schematic diagram of a surface structure unit with resistance loading frequency selection in an ultrawideband thin-layer three-dimensional absorbing metamaterial structure unit according to one embodiment of the present disclosure.

[0014] Figure 5 The reflection coefficient and absorptivity of the loaded metasurface under different oblique incidence angles and TE polarization according to one embodiment of the present disclosure.

[0015] Figure 6 The reflection coefficient and absorptivity of the loaded metasurface under different oblique incidence angles and TM polarization according to one embodiment of the present disclosure.

[0016] Figure 7 According to one embodiment of the present disclosure, without loading a metasurface, the reflection coefficient and absorptivity under TE polarization at different oblique incident angles.

[0017] Figure 8 According to one embodiment of this disclosure, without loading a metasurface, the reflection coefficient and absorptivity under TM polarization at different oblique incident angles.

[0018] Figure 9 The reflection coefficient and absorptivity under TE polarization at different oblique incidence angles, according to one embodiment of the present disclosure.

[0019] Figure 10 The reflection coefficient and absorptivity under TM polarization at different oblique incidence angles, according to one embodiment of the present disclosure.

[0020] Figure 11A schematic diagram of the exploded structure of an ultrawideband thin-layer three-dimensional absorbing metamaterial according to one embodiment of the present disclosure.

[0021] Wherein, 1 represents the first three-dimensional superstructure;

[0022] 2—Second resistive film (loaded on the surface of the first three-dimensional superstructure protrusion);

[0023] 3—Third resistive film (loaded on the first side of the first three-dimensional superstructure step);

[0024] 4—Fourth resistive film (loaded on the second side of the first three-dimensional superstructure step);

[0025] 5 — First structural unit (structural unit located on the surface where the resistor loading frequency is selected);

[0026] 6—Substrate of the first structure (substrate of the structural unit of the resistive loading frequency selective surface);

[0027] 7—The fifth resistive film (loaded on the first surface of the second three-dimensional superstructure);

[0028] 8—Metasurface (loaded on the second surface of the second three-dimensional metastructure);

[0029] 9—Second three-dimensional superstructure;

[0030] 10 — First lumped resistance (the first lumped resistance on the structural unit of the surface where the resistance loading frequency is selected).

[0031] 11 — Second lumped resistance (second lumped resistance on the structural unit of the surface where the resistance loading frequency is selected).

[0032] 12 — Third total resistance (the third total resistance on the structural unit of the surface where the resistance loading frequency is selected). Detailed Implementation

[0033] The purpose of this disclosure is to provide an ultrawideband thin-film three-dimensional absorbing metamaterial. This is achieved by loading a non-destructive two-dimensional metasurface, a resistance-loaded frequency-selective surface, and a resistive film onto a three-dimensional metastructure possessing dielectric loss characteristics, thereby achieving a thickness of less than 0.06λ. L It covers multiple absorption frequency bands with a continuous absorption bandwidth greater than 42.0 GHz and an oblique incidence angle greater than 45°, meeting the current demand for electromagnetic absorbing materials.

[0034] According to one or more embodiments, the ultrawideband thin-film three-dimensional absorbing metamaterial of this disclosure is composed of three stacked parts, from top to bottom: a first three-dimensional metastructure, a resistive frequency selective surface, and a second three-dimensional metastructure. The first three-dimensional structure is an inverted stepped structure, with the geometry of each step gradually decreasing in size, and resistive films 2, 3, and 4 are loaded on it. The resistive frequency selective surface is composed of a metal structural unit 5 loaded with lumped resistance and its substrate 6. The second three-dimensional structure is a tower-shaped structure, on which resistive films 7 and a metal metasurface 8 are loaded.

[0035] The ultra-wideband thin-layer three-dimensional absorbing metamaterial can be periodically arranged and shaped in the X and Y directions in a two-dimensional plane according to the actual size requirements, depending on the specific application scenario. The period size is 12.0~30.0mm.

[0036] The ultra-wideband thin-layer three-dimensional absorbing metamaterial, wherein the first and second three-dimensional metastructures can be made of materials with certain electromagnetic loss characteristics, such as PLA, PETG, TPU, PVA, BVOH, ABS, ASA, PC, PA, PET, Carbon / Glass Fiber Reinforced PLA, PPA-CF / GF, PPS, PPS-CF / GF, etc., with a relative permittivity ranging from 2.0 to 20.0 and a dielectric loss ranging from 0.001 to 0.1.

[0037] The ultrawideband thin-layer three-dimensional absorbing metamaterial described above has a uniform sheet resistance resistive film loaded on the first three-dimensional metastructure. Specifically, the thickness of the sheet resistance film 2 (flat structure) is 0.3~2.0 mm, and it can be any symmetrical geometric shape, with its maximum size smaller than the maximum size of the inner wall of the rectangular prism of the resistive film 3. The sheet resistance of the resistive film 2 ranges from 10 to 1000 Ω / □. The three-dimensional structure of the resistive film 3 is a hollow rectangular prism with a thickness of 0.5~6.0 mm. The resistive film 3 is loaded on the outer and inner walls of the hollow rectangular prism, with its maximum size smaller than the period. The sheet resistance of the resistive film 3 also ranges from 10 to 1000 Ω / □. The three-dimensional structure of the resistive film 4 is also a hollow rectangular prism with a thickness of 0.5~6.0 mm. The resistive film 4 is loaded on the outer and inner walls of the hollow rectangular prism, with its maximum size smaller than the size of the outer wall of the three-dimensional structure of the resistive film 3. The sheet resistance of the resistive film 4 also ranges from 10 to 1000 Ω / □. Resistive films can be obtained through methods such as screen printing and spraying conductive paste.

[0038] The ultrawideband thin-layer three-dimensional absorbing metamaterial has a lumped resistance loading frequency-selective surface metal structure unit composed of four identical irregular square rings rotated 90° and connected. The side length of the square rings is between 3.5 and 7.0 mm, and each square ring has the same metal branch with a length between 2.0 and 39.0 mm. The four branches are rotated symmetrically with a 90° rotation. A lumped resistance 10 with a value of 50 to 400 Ω is loaded on the metal branches. The outer edge of each square ring has a wider line width, between 0.5 and 1.2 mm, on which a lumped resistance 11 with a value of 200 to 1000 Ω is loaded. The inner edge has a narrower line width, between 0.2 and 1.0 mm, on which a lumped resistance 12 with a value of 200 to 1000 Ω is loaded. There are right-angle gaps at the corners of the outer edge of the square rings. The length of each gap is less than half the length of the edge, and the width is less than the width of the edge.

[0039] The ultrawideband thin-layer three-dimensional absorbing metamaterial has metal units of gold, silver, or copper as the metal structural units of the lumped resistance loaded frequency selective surface, which are prepared on the substrate of the lumped resistance loaded frequency selective surface by methods such as inkjet printing, electrochemical etching, or magnetron sputtering.

[0040] The lumped resistor used on the surface can be obtained through methods such as screen printing or spraying conductive paste, or it can be directly loaded with commercial chip resistors through PCB manufacturing processes.

[0041] The material of the lumped resistance loading frequency selection surface can be one of the common PCB board materials such as PI film, PEN film, FR4 board, and F4B board, with a relative permittivity of 2.0~5.0 and a thickness of 0.1~0.5mm.

[0042] The ultrawideband thin-layer three-dimensional absorbing metamaterial has a uniform sheet resistance resistive film 7 loaded on the second three-dimensional metastructure. The three-dimensional structure of the resistive film 7 is a hollow cross-shaped column with a thickness of 0.5~6.0mm. The resistive film 7 is loaded on the outer and inner walls of the hollow cross-shaped column, with the long side being smaller than the period. The sheet resistance of the resistive film 7 ranges from 10 to 700Ω / □. The resistive film can be obtained by screen printing, spraying conductive paste, etc.

[0043] The ultra-wideband thin-layer three-dimensional absorbing metamaterial has a metasurface 8 on the second three-dimensional metastructure whose structural unit is a slotted metal square ring. The side length of the square ring is 11.0~29.0mm, the width is 0.6~1.6mm, the length of the slot is less than the side length of the square ring, and the width is less than the width of the square ring.

[0044] The ultra-wideband thin-layer three-dimensional absorbing metamaterial, the metal unit of the metal structure unit of the metasurface 8 and the metal unit of the metasurface are made of gold, silver and copper metal materials, and are prepared and attached to the second three-dimensional metastructure by methods such as inkjet printing, magnetron sputtering and bonding.

[0045] The first and second three-dimensional structures of the ultrawideband thin-layer three-dimensional absorbing metamaterial disclosed herein can be prepared by 3D printing or engraving processes.

[0046] The design principles involved in this disclosed ultrawideband thin-layer three-dimensional absorbing metamaterial include:

[0047] a. The absorption performance is mainly achieved through three functional structures: the first three-dimensional superstructure and the second three-dimensional superstructure, which are mainly used to achieve the absorption performance in the high-frequency band of 18.0-50.0 GHz. The resistive frequency selective surface is mainly used to achieve the absorption performance in the mid-frequency band of 5.0-18.0 GHz. The metal metasurface 8 loaded on the second three-dimensional superstructure is mainly used to achieve the narrowband absorption performance near the low-frequency band of 2.7 GHz.

[0048] b. The second three-dimensional superstructure achieves the control of its equivalent dielectric constant through a hollow tower-shaped structure design. By covering the inner and outer walls of the bottom hollow cross column with a uniform resistive film to increase loss, the high-frequency absorption band is broadened.

[0049] c. By designing the hollow tower-shaped structure of the second three-dimensional superstructure, a metal metasurface 8 was directly attached to the surface of the first layer of the three-dimensional superstructure. Electromagnetic absorption performance was achieved by utilizing the loss characteristics of the second three-dimensional structure, thus realizing the functional reuse of the three-dimensional structure.

[0050] d. The resistive frequency selective surface achieves miniaturization through a spiral stub design, controls its impedance characteristics through a ring-shaped slit structure design, and meets the loss circuit impedance requirements of the absorption frequency band by loading resistors with different local resistance values, thereby achieving strong absorption performance at different oblique incidence angles and increasing the oblique incidence angle.

[0051] e. The inverted step structure design of the first three-dimensional superstructure realizes the addition of uniform resistive films with different sheet resistances on different steps. Through the non-gradient change loading design of the resistive film, the impedance matching control and absorption performance enhancement of the structure under different oblique incident angles in three-dimensional space are realized.

[0052] f. The inverted step structure design of the first three-dimensional metastructure enables the ultra-wideband thin-layer three-dimensional absorbing metamaterial of this disclosure to have a surface protective layer, reducing the influence of external environmental factors on the internal functional layer.

[0053] Therefore, the beneficial effects of the embodiments disclosed herein include:

[0054] a. The present disclosure provides an ultra-wideband thin-layer three-dimensional absorbing metamaterial that can cover the L, S, C, X, Ku, K, and Ka frequency bands when electromagnetic waves are incident perpendicularly, and has a continuous absorption bandwidth greater than 42.0 GHz, achieving multi-band, ultra-wideband absorption performance;

[0055] b. This disclosure provides an ultrawideband thin-film three-dimensional absorbing metamaterial with a relative thickness of less than 0.06λ. L This enables multi-band, ultra-wideband absorption in an ultra-thin thickness.

[0056] c. The ultra-wideband thin-layer three-dimensional absorbing metamaterial provided in this disclosure has the following absorption performance under TE polarization: for the reflection coefficient below -10 dB, the oblique incidence angle at the L-band absorption frequency is 30°, and the oblique incidence angles at the S, C, X, Ku, K, and Ka frequency bands are greater than 45°.

[0057] d. Under TM polarization, for absorption performance with a reflection coefficient below -10 dB, the oblique incidence angle of the S, C, X, Ku, K, and Ka bands is greater than 60°. In addition, at an oblique incidence angle of about 45°, there is an absorption band with a reflection coefficient below -20 dB and an absolute bandwidth of not less than 22 GHz.

[0058] According to one or more embodiments, an ultrawideband thin-film three-dimensional absorbing metamaterial comprises three parts: a first three-dimensional metastructure, a resistive frequency selective surface, and a second three-dimensional metastructure. The first three-dimensional structure is an inverted stepped structure, with the geometry of each step gradually decreasing in size, and resistive films 2, 3, and 4 are loaded on it. The resistive frequency selective surface is composed of a metal structural unit 5 loaded with lumped resistance and its substrate 6. The second three-dimensional structure is a tower-shaped structure, on which resistive films 7 and a metal metasurface 8 are loaded.

[0059] The materials of the first and second three-dimensional superstructures can be PLA, PETG, TPU, PVA, BVOH, ABS, ASA, PC, PA, PET, Carbon / Glass Fiber Reinforced PLA, PPA-CF / GF, PPS, PPS-CF / GF, etc., which have certain electromagnetic loss characteristics. The relative permittivity ranges from 2.0 to 20.0, and the dielectric loss ranges from 0.001 to 0.5. The thickness of the first and second three-dimensional superstructures is 0.5 to 5.0 mm.

[0060] The resistive film loaded on the first three-dimensional superstructure is a uniform sheet resistance resistive film. Specifically, the thickness of the sheet resistance film 2 (flat structure) is 0.3~2.0 mm, and it can be any symmetrical geometric shape. Its maximum size is smaller than the maximum size of the inner wall of the rectangular prism of the resistive film 3. The sheet resistance of the resistive film 2 ranges from 10 to 1000 Ω / □. The three-dimensional structure of the resistive film 3 is a hollow rectangular prism with a thickness of 0.5~6.0 mm. The resistive film 3 is loaded on the outer and inner walls of the hollow rectangular prism, and its maximum size is smaller than the period. The sheet resistance of the resistive film 3 ranges from 10 to 1000 Ω / □. The three-dimensional structure of the resistive film 4 is a hollow rectangular prism with a thickness of 0.5~6.0 mm. The resistive film 4 is loaded on the outer and inner walls of the hollow rectangular prism, and its maximum size is smaller than the size of the outer wall of the three-dimensional structure of the resistive film 3. The sheet resistance of the resistive film 4 ranges from 10 to 1000 Ω / □. The resistive films can be obtained through methods such as screen printing or spraying conductive paste.

[0061] The ultrawideband thin-layer three-dimensional absorbing metamaterial has a lumped resistance loading frequency-selective surface metal structure unit composed of four identical irregular square rings connected together. The side length of the square rings is between 3.5 and 7.0 mm, and each square ring has the same metal branches with a length between 2.0 and 39.0 mm. The branches are arranged in a spiral shape. A lumped resistance 10 with a value of 50 to 400 Ω is loaded on the metal branches. The outer edge of each square ring has a wider line width, between 0.5 and 1.2 mm, on which a lumped resistance 11 with a value of 200 to 1000 Ω is loaded. The inner edge has a narrower line width, between 0.2 and 1.0 mm, on which a lumped resistance 12 with a value of 200 to 1000 Ω is loaded. There are right-angle gaps at the corners of the outer edge of the square rings. The length of each gap is less than half the side length, and the width is less than the side width.

[0062] The material of the lumped resistance loading frequency selection surface can be one of the common PCB board materials such as PI film, PEN film, FR4 board, and F4B board, with a relative permittivity of 2.0~5.0 and a thickness of 0.1~0.5mm.

[0063] The ultrawideband thin-layer three-dimensional absorbing metamaterial has a uniform sheet resistance resistive film 7 loaded on the second three-dimensional metastructure. The three-dimensional structure on which the resistive film 7 is loaded is a hollow cross-shaped column with a thickness of 0.5~6.0mm. The resistive film 7 is loaded on the outer and inner walls of the hollow cross-shaped column, with the long side being smaller than the period. The sheet resistance of the resistive film 7 ranges from 10 to 700Ω / □.

[0064] The ultra-wideband thin-layer three-dimensional absorbing metamaterial has a metasurface 8 on the second three-dimensional metastructure whose structural unit is a slotted metal square ring. The side length of the square ring is 11.0~29.0mm, the width is 0.6~1.6mm, the length of the slot is less than the side length of the square ring, and the width is less than the width of the square ring.

[0065] According to one or more embodiments, a schematic diagram of an ultrawideband thin-layer three-dimensional absorbing metamaterial structure is shown below. Figure 1 As shown, from top to bottom, it consists of three parts: a first three-dimensional superstructure, a resistive frequency selective surface, and a second three-dimensional superstructure. The first three-dimensional structure is an inverted stepped structure, with the geometry of each step gradually decreasing in size, and resistive films 2, 3, and 4 are loaded on it. The resistive frequency selective surface is composed of a metal structural unit 5 loaded with lumped resistance and its substrate 6. The second three-dimensional structure is a tower-shaped structure, on which resistive film 7 and a metal metasurface 8 are loaded.

[0066] The ultra-wideband thin-layer three-dimensional absorbing metamaterial described in the embodiment was simulated and verified using electromagnetic simulation software CST 2025. A Floquet port was used, and the simulation of an infinitely large plane was achieved through a Unit cell, with a period of 14.0~18.0 mm.

[0067] The ultra-wideband thin-layer three-dimensional absorbing metamaterial described in the embodiment can be made of PLA / CF, with a relative permittivity ranging from 2.9 to 3.5 and a dielectric loss ranging from 0.01 to 0.1.

[0068] The ultra-wideband thin-layer three-dimensional absorbing metamaterial of the embodiment has a uniform sheet resistance resistive film loaded on the first three-dimensional metastructure. Specifically, the thickness of the sheet resistance film 2 (flat structure) is 0.3~2.0 mm, and it can be any symmetrical geometric shape, with its maximum size smaller than the maximum size of the inner wall of the rectangular prism of the sheet resistance film 3. The sheet resistance of the sheet resistance film 2 ranges from 100~400 Ω / □. The three-dimensional structure of the sheet resistance film 3 is a hollow rectangular prism with a thickness of 0.5~6.0 mm. The sheet resistance film 3 is loaded on the outer and inner walls of the hollow rectangular prism, with its maximum size smaller than the period. The sheet resistance of the sheet resistance film 3 ranges from 100~400 Ω / □. The three-dimensional structure of the sheet resistance film 4 is also a hollow rectangular prism with a thickness of 0.6~1.6 mm. The sheet resistance film 4 is loaded on the outer and inner walls of the hollow rectangular prism, with its maximum size smaller than the size of the outer wall of the three-dimensional structure of the sheet resistance film 3. The sheet resistance of the sheet resistance film 4 ranges from 50~200 Ω / □. Resistive films can be obtained through screen printing.

[0069] The ultrawideband thin-layer three-dimensional absorbing metamaterial of the embodiment has a lumped resistance loading frequency-selective surface metal structure unit composed of four identical irregular square rings connected together. The side length of the square rings is between 4.0 and 6.0 mm, and each square ring has the same metal branches with a length between 12.0 and 17.0 mm. The branches are arranged in a spiral shape. A lumped resistance 10 with a value of 50 to 300 Ω is loaded on the metal branches. The outer edge of each square ring has a wider line width, between 0.6 and 1.0 mm, on which a lumped resistance 11 with a value of 250 to 400 Ω is loaded. The inner edge has a narrower line width, between 0.2 and 0.9 mm, on which a lumped resistance 12 with a value of 250 to 500 Ω is loaded. There are right-angle gaps at the corners of the outer edge of the square rings. The length of each gap is less than half the side length, and the width is less than the side width.

[0070] The ultra-wideband thin-layer three-dimensional absorbing metamaterial of the embodiment has metal units of the lumped resistance loaded frequency selective surface, which are made of gold, silver or copper metals, and are prepared on the substrate of the lumped resistance loaded frequency selective surface by means of inkjet printing, electrochemical etching or magnetron sputtering.

[0071] The lumped resistor used on the surface can be obtained through methods such as screen printing or spraying conductive paste, or it can be directly loaded with commercial chip resistors through PCB manufacturing processes.

[0072] In the embodiment of the ultra-wideband thin-layer three-dimensional absorbing metamaterial, the lumped resistance loading frequency selection surface material is a PI film with a relative permittivity of 3.0~3.5 and a thickness of 0.1~0.4mm.

[0073] The ultrawideband thin-layer three-dimensional absorbing metamaterial has a uniform sheet resistance resistive film 7 loaded on the second three-dimensional metastructure. The three-dimensional structure of the loaded resistive film 7 is a hollow cross-shaped column with a thickness of 0.5-4.0 mm. The resistive film 7 has a value range of 50~400Ω / □. The resistive film can be obtained by screen printing, spraying conductive paste, etc.

[0074] The ultra-wideband thin-layer three-dimensional absorbing metamaterial has a metasurface 8 on the second three-dimensional metastructure whose structural unit is a slotted metal square ring. The square ring has a side length of 11.5~16.0mm and a width of 0.6~1.2mm. The length of the slot is less than the side length of the square ring and the width is less than the width of the square ring.

[0075] The ultra-wideband thin-layer three-dimensional absorbing metamaterial, the metal units of the metal structure unit of the metasurface 8 and the metasurface metal unit are made of copper metal, and are attached to the second three-dimensional metastructure by bonding.

[0076] The first and second three-dimensional structures of the ultra-wideband thin-layer three-dimensional absorbing metamaterial in the embodiment were prepared by 3D printing.

[0077] like Figure 5 The figures show the reflection coefficient and absorptivity of the metasurface loaded in this embodiment under different oblique incidence angles and TE polarization. It can be seen that a single metallic metasurface 8 can achieve absorption peaks at different frequency points. In this embodiment, it is mainly used to achieve an absorption peak at 2.7 GHz. For absorption performance with a reflection coefficient below -10 dB, the oblique incidence angle at the L-band absorption frequency is 45°. In the figure, "theta" (θ) represents the oblique incidence angle.

[0078] Figure 6 These are the reflection coefficient and absorptivity of the metasurface loaded in this embodiment under different oblique incidence angles and TM polarization. It can be seen that a single metallic metasurface 8 can achieve absorption peaks at different frequency points. In this embodiment, it is mainly used to achieve an absorption peak at 2.7 GHz. For absorption performance with a reflection coefficient below -10 dB, the oblique incidence at the L-band absorption frequency is 60°.

[0079] Figure 7 This disclosure presents the reflection coefficient and absorptivity under TE polarization at different oblique incidence angles without a metasurface. For perpendicular incidence, the absorption frequency band with a reflection coefficient below -10dB (corresponding to an absorptivity of 90%) is 5.5~40.0GHz / 40.3~50.0GHz. For oblique incidence angles greater than 45°, and with an incidence angle of 60°, the absorptivity is greater than 80% in the 6.4~29.8GHz / 40.8~50.0GHz range.

[0080] Figure 8 This disclosure presents the reflection coefficient and absorptivity under different oblique incidence angles with TM polarization when no metasurface is loaded in the embodiments of this disclosure. For perpendicular incidence, the absorption frequency band with a reflection coefficient below -10dB is 5.5~40.0GHz / 40.3~50.0GHz; for an oblique incidence angle of 45°, the absorption frequency band with a reflection coefficient below -10dB is 7.4~50.0GHz, and the frequency band with a reflection coefficient below -20dB (corresponding to an absorptivity of 99%) is 17.0~35.7GHz; and for an incidence angle of 60°, the absorption frequency band with a reflection coefficient below -10dB is 10.9~50.0GHz.

[0081] Figure 9This disclosure presents an embodiment of the reflection coefficient and absorptivity under TE polarization at different oblique incidence angles. With vertical incidence, a strong absorption frequency with an absorptivity greater than 97.6% is observed at 2.74 GHz, and the absorption band with a reflection coefficient below -10 dB (corresponding to an absorptivity of 90%) is 5.7–50.0 GHz. With an oblique incidence angle of 45°, the strong absorption frequency in the L-band shifts only slightly to 2.81 GHz, with an absorptivity greater than 86.5%, and the absorption band with a reflection coefficient below -10 dB is 5.7–50.0 GHz, demonstrating good oblique incidence stability. With an incidence angle of 60°, the absorptivity is greater than 80% in the ranges of 6.9–32.9 GHz and 43.4–50.0 GHz.

[0082] Figure 10 This disclosure describes the reflection coefficient and absorptivity under TM polarization at different oblique incidence angles. With vertical incidence, a strong absorption frequency with an absorptivity greater than 97.6% is observed at 2.74 GHz, and the absorption band with a reflection coefficient below -10 dB (corresponding to an absorptivity of 90%) is 5.7–50.0 GHz. With an oblique incidence angle of 45°, the strong absorption frequency in the L-band shifts only slightly to 2.73 GHz, with an absorptivity greater than 97.5%, and absorption bands with reflection coefficients below -10 dB and -20 dB are 7.8–50.0 GHz and 13.2–36.0 GHz, respectively. With an incidence angle of 60°, the frequency bands with absorptivity greater than 90% and 80% are 7.8–50.0 GHz and 6.3–50.0 GHz, respectively, demonstrating good oblique incidence performance.

[0083] Therefore, this disclosure provides an ultrawideband thin-film three-dimensional absorbing metamaterial. By loading a non-destructive two-dimensional metasurface, a resistance-loaded frequency-selective surface, and a resistive film onto a three-dimensional metastructure with dielectric loss characteristics, it is possible to achieve a relative thickness of less than 0.06λ. L With its performance covering multiple absorption frequency bands and a continuous absorption bandwidth greater than 42.0 GHz, and an oblique incidence angle greater than 45°, it meets the current demand for electromagnetic absorbing materials, making it extremely valuable in the fields of reducing electromagnetic radiation and electromagnetic protection.

[0084] It should be understood that in the embodiments of this disclosure, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0085] It is worth noting that although the foregoing has described the spirit and principles of this disclosure with reference to several specific embodiments, it should be understood that this disclosure is not limited to the disclosed specific embodiments, and the division of aspects does not imply that the features in these aspects cannot be combined; such division is merely for the convenience of expression. This disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A three-dimensional microwave absorbing metamaterial unit structure, characterized in that, The unit structure comprises a first three-dimensional superstructure, a resistive frequency-selective surface, and a second three-dimensional superstructure sequentially combined, wherein... The first three-dimensional superstructure has an inverted stepped structure, with each step having a hollow square column geometry that gradually decreases in size from top to bottom. A boss is provided in the hollow part of each hollow square column, and a resistive film is loaded onto the surface of the boss. Resistive films are loaded onto the outer and inner walls of each hollow square column. The first three-dimensional superstructure is connected to the resistive frequency selection surface through the boss surface. The second three-dimensional superstructure is loaded with a metasurface, which is a slotted metal square ring; the second three-dimensional superstructure also includes a hollow cross-shaped three-dimensional structure, which is disposed inside the slotted metal square ring, and the outer and inner walls of the hollow cross-shaped three-dimensional structure are loaded with resistive films; the second three-dimensional superstructure has a hollow column, which is disposed in the hollow part of the hollow cross-shaped column, and the top surface of the hollow column is combined with the resistive frequency selection surface; The resistive frequency selection surface is composed of a metal structural unit with a lumped resistor and a substrate. The metal structural unit is composed of four identical irregular square rings rotated 90° and connected. Each side of the square ring has a gap, and a lumped resistor is loaded at the gap. Each square ring has the same metal branch, and the four branches are rotated 90° symmetrically. A lumped resistor is loaded on the metal branch.

2. A three-dimensional microwave absorbing metamaterial, characterized in that, It includes an array composed of multiple unit structures as described in claim 1.

3. A method for preparing a three-dimensional microwave absorbing metamaterial, characterized in that, The method for preparing the metamaterial as described in claim 2 includes at least a 3D printing process or an engraving process.

4. An electronic device, characterized in that, The electronic device employs at least the three-dimensional absorbing metamaterial as described in claim 2.

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