WO2012129924A1 - 一种吸波超材料 - Google Patents

一种吸波超材料 Download PDF

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Publication number
WO2012129924A1
WO2012129924A1 PCT/CN2011/083221 CN2011083221W WO2012129924A1 WO 2012129924 A1 WO2012129924 A1 WO 2012129924A1 CN 2011083221 W CN2011083221 W CN 2011083221W WO 2012129924 A1 WO2012129924 A1 WO 2012129924A1
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WIPO (PCT)
Prior art keywords
metal
metamaterial
substrate
branch
absorbing
Prior art date
Application number
PCT/CN2011/083221
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English (en)
French (fr)
Inventor
刘若鹏
栾琳
赵治亚
王文剑
Original Assignee
深圳光启高等理工研究院
深圳光启创新技术有限公司
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Priority claimed from CN 201110081014 external-priority patent/CN102480909B/zh
Priority claimed from CN201110080843.3A external-priority patent/CN102892278B/zh
Application filed by 深圳光启高等理工研究院, 深圳光启创新技术有限公司 filed Critical 深圳光启高等理工研究院
Priority to US14/009,023 priority Critical patent/US9208913B2/en
Priority to EP11862653.0A priority patent/EP2693860B1/en
Publication of WO2012129924A1 publication Critical patent/WO2012129924A1/zh

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Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F1/00—Shielding characterised by the composition of the materials
    • G21F1/02—Selection of uniform shielding materials
    • G21F1/08—Metals; Alloys; Cermets, i.e. sintered mixtures of ceramics and metals
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • H05K9/0086—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising a single discontinuous metallic layer on an electrically insulating supporting structure, e.g. metal grid, perforated metal foil, film, aggregated flakes, sintering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H01Q17/002—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems using short elongated elements as dissipative material, e.g. metallic threads or flake-like particles

Definitions

  • the invention relates to a wave absorbing material, in particular to a wave absorbing super material. ⁇ Background technique ⁇
  • Absorbing materials are functional composites that absorb and attenuate the energy of incident electromagnetic waves and convert their electromagnetic energy into thermal or other forms of energy through the dielectric loss of the material. Absorbing materials have great application prospects in the control of electromagnetic pollution and the manufacture of stealth materials.
  • the commonly used absorbing materials are ferrite, barium titanate, metal micropowder, graphite, silicon carbide, conductive fiber, etc.
  • ferrite absorbing materials are more and more mature absorbing materials.
  • Ferrite has a high magnetic permeability and electrical resistivity at high frequencies, and electromagnetic waves are easy to enter and can be rapidly attenuated.
  • such a absorbing material represented by ferrite has defects such as poor high-temperature characteristics, large areal density, and difficulty in matching electromagnetic parameters.
  • the technical problem to be solved by the present invention is to provide a absorbing wave metamaterial having good absorbing performance, light weight, thin thickness and easy adjustment of electromagnetic parameters in view of the above-mentioned deficiencies of the prior art.
  • the technical solution adopted by the present invention to solve the technical problem thereof is to provide a absorbing wave metamaterial comprising a substrate, a plurality of artificial metal microstructures periodically arranged inside the substrate; and the super material when electromagnetic waves pass through the metamaterial
  • the relative dielectric constant and relative magnetic permeability are approximately equal.
  • an imaginary part of a relative dielectric constant and/or a relative magnetic permeability of the metamaterial is greater than an imaginary part of a relative dielectric constant and/or a relative magnetic permeability of the substrate such that the electromagnetic wave is absorbed.
  • the absorbing wave metamaterial comprises a substrate having two opposite side surfaces, at least one side surface having a plurality of artificial metal microstructures periodically arranged thereon; when the incident direction is perpendicular to the opposite side surfaces of the substrate.
  • the relative dielectric constant and relative magnetic permeability of the metamaterial are substantially equal when the electromagnetic wave passes through the metamaterial.
  • the metamaterial when the electromagnetic wave having an incident direction perpendicular to opposite side surfaces of the substrate passes through the metamaterial The imaginary part of the relative dielectric constant and/or the imaginary part of the relative magnetic permeability is greater than the imaginary part of the relative dielectric constant of the substrate and/or the imaginary part of the relative magnetic permeability such that the electromagnetic wave is absorbed.
  • a first man-made metal microstructure is attached to one surface of the opposite side surfaces of the substrate, and a second man-made metal microstructure corresponding to the first man-made metal microstructure is attached to the other side surface;
  • the man-made metal microstructure includes two first metal branches that are perpendicular to each other and connected in a "ten" shape, respectively connected to the second metal branches at both ends of the first metal branch and perpendicular to the first metal branch;
  • the metal microstructure is composed of a third metal branch having a quadrangular shape with a notch on one side.
  • a midpoint of each of the second metal branches of the first man-made metal microstructure is respectively disposed at an end point of the first metal branch connected thereto; the second man-made metal microstructure is square-shaped having a notch at a midpoint of the side
  • the third metal branch is formed.
  • the man-made metal microstructure includes a first metal branch, the first metal branch forming a quadrilateral shape having a notch on one side; one end is disposed on the opposite quadrilateral side of the notch and extends toward the notch and protrudes the second metal branch of the notch; a third metal branch at the other end of the second metal branch.
  • the man-made metal microstructure has a bilaterally symmetric structure with the second metal branch as a symmetry axis.
  • the substrate is a sheet-like substrate, and the metamaterial is formed by stacking the sheet-like substrates to which a plurality of the man-made metal microstructures are attached.
  • the man-made metal microstructure is formed by three identical planar topologies perpendicularly intersecting at a common center point in three dimensions.
  • the planar topology includes: two first metal branches intersecting each other perpendicularly in a "ten" shape; respectively connected to the two ends of the two first metal branches, having a length smaller than the first metal branch and perpendicular to the first metal branch Four second metal branches; eight third metal branches extending inwardly from both ends of the second metal branch; a fourth metal branch having a notch on one side and disposed in a plane surrounded by the four second metal branches The fourth metal branch has a length shorter than the second metal branch and a side having the gap does not intersect the first metal branch, and the other three sides intersect the first metal branch.
  • the planar topology also includes two fifth metal branches extending inwardly from opposite ends of the gap.
  • the third metal branch forms an angle of 45 ° with the second metal branch connected thereto.
  • the fourth metal branch center point coincides with two of the first metal branch intersections.
  • the substrate is composed of a plurality of sheet-like substrates, and a plurality of metal branches are attached to each of the sheet-like substrates; and when a plurality of the sheet-like substrates are combined, they are attached to the plurality of the sheet-like substrates.
  • a plurality of the metal branches are combined into the man-made metal microstructure.
  • the substrate is a high molecular polymer, a ceramic, a ferroelectric material, a ferrite material or a ferromagnetic material.
  • a plurality of the artificial metal microstructures periodically arranged are adhered to at least one surface of the opposite side surfaces of the substrate by etching, electroplating, drilling, photolithography, electron engraving, and ion etching.
  • the invention adopts the absorbing principle different from the traditional absorbing material, and achieves the ideal absorbing effect by arranging various artificial metal microstructures on the substrate periodically and adjusting the size of the artificial metal microstructure, which has light weight and thickness. Thin, low interference from external environment and easy adjustment of electromagnetic parameters.
  • the artificial metal microstructure of the present invention can be a three-dimensional structure, which can effectively absorb electromagnetic waves in any three-dimensional incident direction, and improves the practicability of the absorbing wave metamaterial.
  • the present invention adopts a method in which a sheet substrate is combined into a unitary substrate to constitute a metamaterial, so that the size and spacing of the artificial metal microstructure inside the metamaterial can be conveniently adjusted separately, that is, the relative of the metamaterial of the present invention. The dielectric constant and relative magnetic permeability are easily adjusted.
  • Figure 1 is a first artificial metal microstructure view attached to a side surface of a substrate in a first preferred embodiment of the wave absorbing material of the present invention
  • FIG. 2 is a second artificial metal microstructure view attached to the other side surface of the substrate in the first preferred embodiment of the wave absorbing material of the present invention
  • FIG. 3 is a view showing a microstructure of an artificial metal in a second preferred embodiment of the absorbing wave metamaterial of the present invention.
  • Figure 4 is a view showing the incident electromagnetic wave of the artificial metal microstructure in the second preferred embodiment of the absorbing wave metamaterial of the present invention. Decomposition diagram of field and magnetic field response;
  • Figure 5 is a schematic view showing the relationship between the relative dielectric constant ⁇ of the absorbing wave metamaterial of the present invention and the ⁇ -f of the electromagnetic wave frequency f;
  • FIG. 6 is a schematic view showing the relationship between the relative magnetic permeability ⁇ of the absorbing material of the present invention and the frequency f of the electromagnetic wave f;
  • FIG. 7 is a second preferred embodiment of the absorbing wave metamaterial of the present invention, wherein the artificial metal microstructure is attached to the substrate. a computer simulation rendering of one side surface;
  • Figure 8 is a plan top view showing the three-dimensional structure of the man-made metal microstructure in the third preferred embodiment of the absorbing wave metamaterial of the present invention.
  • FIG. 9 is a perspective view showing a three-dimensional structure of a man-made metal microstructure in a third preferred embodiment of the absorbing wave metamaterial of the present invention.
  • FIG. a plurality of equivalent topologies that are responsive to an electric field that are resolved perpendicular to the electromagnetic waves incident on the plane;
  • FIG. 11 is a plurality of equivalent topological views of a magnetic field response of a man-made metal microstructure in accordance with a third preferred embodiment of the absorbing wave metamaterial of the present invention in response to electromagnetic waves incident in a three-dimensional space perpendicular to the plane;
  • Fig. 12 is a derivative diagram showing a planar topological view of a three-dimensional structure of an artificial metal microstructure in a fourth preferred embodiment of the absorbing wave metamaterial of the present invention.
  • the basic physical principle of the absorbing material is that the material absorbs the incident electromagnetic wave effectively, and the electromagnetic wave energy is converted into thermal energy or other forms of energy and is dissipated.
  • the material should have two characteristics, namely impedance matching characteristics and attenuation characteristics.
  • the impedance matching characteristic refers to a reflection characteristic in which electromagnetic waves incident from the free space to the surface of the absorbing material are reflected by the surface of the absorbing material.
  • the ideal absorbing material should make the electromagnetic wave incident from the free space form zero reflection on the surface of the ideal absorbing material, that is, the electromagnetic wave all enters the ideal absorbing material.
  • the ideal impedance matching characteristic can be achieved when the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ of the absorbing material are equal.
  • the relative dielectric constant ⁇ ⁇ '-" ⁇
  • relative magnetic permeability ⁇ ⁇ '-] ⁇
  • the metamaterial is composed of artificial metal microstructures having a certain pattern shape periodically arranged in a substrate in a specific manner.
  • Each of the man-made metal microstructures and the substrate to which they are attached constitute a basic unit of the metamaterial, and the plurality of metamaterial base units are arranged in a regular pattern so that the metamaterial has a macroscopic response to electromagnetic waves.
  • the response of each metamaterial basic unit to the incident electromagnetic wave needs to form a continuous response, which requires that the size of each metamaterial basic unit is less than one fifth of the incident electromagnetic wave wavelength, preferably One tenth of the wavelength of the incident electromagnetic wave.
  • we artificially divide the supermaterial into a plurality of basic units of metamaterials but it should be understood that this method of division is only convenient for description, and should not be regarded as supermaterial being spliced or assembled by multiple metamaterial basic units.
  • the super material is formed by arranging the artificial metal microstructure period on the substrate, and the process is simple and the cost is low.
  • the periodic arrangement means that the man-made metal microstructures on the basic units of each metamaterial divided by us can produce a continuous electromagnetic response to incident electromagnetic waves.
  • the pattern shape or size of the man-made metal microstructure on each of the metamaterial base elements is varied such that the supermaterials have different dielectric constants and different magnetic permeability such that the metamaterials have different electromagnetic responses.
  • the invention utilizes the above principle of metamaterial to design a metamaterial capable of strongly absorbing electromagnetic waves in a specific frequency band.
  • the metamaterial includes a substrate having two opposite side surfaces to which a plurality of periodically arranged man-made metal microstructures are attached on at least one side surface of the opposite side surfaces.
  • the surface of the substrate When the surface of the substrate is not attached with the artificial metal microstructure, it exhibits an initial relative dielectric constant ⁇ and an initial relative permeability ⁇ 1 for the electromagnetic field ; when the artificial metal microstructure is attached to the surface of the substrate, the artificial metal microstructure Responding to the incident electromagnetic field, so that the substrate and the man-made metal microstructure constitute a metamaterial.
  • the response of the metamaterial to the electromagnetic field changes due to the change of the microstructure of the man-made metal, that is, the relative dielectric constant ⁇ and relative of the metamaterial.
  • the magnetic permeability ⁇ varies depending on the size of the artificial metal microstructure.
  • the metamaterial is used as the absorbing material, it is necessary to combine the initial relative dielectric constant ⁇ of the substrate and the initial relative magnetic permeability ⁇ to design the topological pattern and size of the initial man-made metal structure to meet the design requirements of the absorbing material, that is, the impedance. Both the matching characteristics and the attenuation characteristics are excellent. Because the artificial metal microstructure needs to respond to both the electric and magnetic fields of the incident electromagnetic wave, the plane of the artificial metal microstructure must have electric and magnetic components.
  • the substrate of the present invention adopts various common materials which have large loss of electromagnetic waves, such as high molecular polymers, ceramics, ferroelectric materials, ferrite materials or ferromagnetic materials, among which
  • the molecular polymer is preferably a FR-4 or F4B material.
  • the first artificial metal microstructure 10 on one side surface of the substrate comprises two first metal branches 11 which are perpendicular to each other and connected in a "ten" shape, respectively connected at both ends of each of the first metal branches 11 and perpendicular to the first metal
  • the second metal branch 12 of the branch 11 The second man-made metal microstructure 20 on the other side surface of the substrate includes a third metal branch 201 which constitutes a quadrilateral shape having a notch 2011 on one side.
  • the two man-made metal microstructures are paired on opposite sides of the substrate.
  • the midpoints of the second metal branches 12 of the first artificial metal microstructures 10 are respectively disposed at the end points of the first metal branches 11 to which they are connected, and the second man-made metal microstructures 20 are notched by the midpoints of the sides.
  • the square-shaped third metal branch 201 of 2011 is constructed.
  • the relative dielectric constant of the metamaterial is the second metal branching area, the second metal branching interval, k is a constant, C is an equivalent capacitance, and the relative dielectric constant ⁇ of the metamaterial can be adjusted by the second The area S of the metal branch 12 and the spacing d of the second metal branch 12 are adjusted, and the pitch d of the second metal branch 12 is the length of the first metal branch 11; the third metal branch 201 of the second artificial metal microstructure 20 A ring current is formed, and according to the right-handed screw rule, the ring current generates a magnetic field to affect the relative magnetic permeability ⁇ of the metamaterial.
  • Adjusting the size and spacing of the metal branches of the first man-made metal microstructure 10 and the second man-made metal microstructure 20 respectively can adjust the response of the man-made metal microstructure to the incident electric field and the incident magnetic field to adjust the relative dielectric constant ⁇ of the overall material.
  • relative magnetic permeability ⁇ The relationship between the relative permittivity ⁇ and the relative permeability ⁇ of the ultra-material as a whole and the frequency f of the electromagnetic wave As shown in Figure 5 and Figure 6. In Fig. 5 and Fig.
  • the electromagnetic wave frequency band required by the present invention is generally a frequency band which deviates from the artificial metal microstructure resonance frequency point and which can attenuate the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ exponentially.
  • this paragraph description is only for describing the regularity of the experimental process of the present invention, and is not intended to limit the electromagnetic wave incident frequency band of the present invention.
  • the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ of the metamaterial are substantially equal to satisfy the design requirement of the impedance matching of the present invention.
  • the so-called basic equality means that the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ have only errors that do not affect the impedance matching effect.
  • the energy loss is mainly characterized by the electrical loss factor tan ⁇ e and the magnetic loss factor tan ⁇ m .
  • ferroelectric materials are mainly electrical loss factors
  • ferromagnetic materials are mainly magnetic loss factors.
  • Ferrite materials are available in both.
  • the effect of the artificial metal microstructure on the overall attenuation characteristics of the metamaterial is to improve the attenuation characteristics of the substrate, that is, to improve the relative dielectric constant of the overall material and/or the imaginary part of the relative magnetic permeability, thereby improving the overall attenuation characteristics of the metamaterial.
  • the man-made metal microstructure 30 includes a first metal branch 301, which has a quadrangular shape with a notch 3011 on one side; one end is disposed on the opposite quadrilateral side of the notch 3011 and extends toward the notch 3011 and protrudes the second of the notch 3011.
  • the artificial metal microstructure 30 is attached to one of the opposite side surfaces of the substrate, preferably, in order to obtain A better absorbing effect adheres to the man-made metal microstructures 30 on both opposite side surfaces of the substrate and the man-made metal microstructures of the opposite side surfaces are mirror symmetrical, more preferably the man-made metal microstructures 30 on each side of the surface.
  • the second metal branch 302 has a bilaterally symmetric structure with the axis of symmetry.
  • the artificial metal microstructure 30 in the preferred embodiment is equivalent to the first artificial metal microstructure 10 and the second artificial metal microstructure 20 in the first preferred embodiment, and the electromagnetic response principle of the vertically incident electromagnetic wave is
  • the first preferred embodiment is the same, that is, the opposite metal branch is equivalent to a capacitive element to adjust the relative dielectric constant ⁇ of the metamaterial, and the current induced on the annular metal branch induces a magnetic field according to the right-handed screw rule to adjust the metamaterial. Relative magnetic permeability. Specifically, in this embodiment, as shown in FIG.
  • the artificial metal microstructure 30 is split into a first portion 30' in the shape of "work” and a second portion 30" in the shape of a quadrangle having one side, the first portion 30
  • the metal branches respectively collect positive and negative charges to form equivalent capacitive elements to adjust the relative dielectric constant of the metamaterial, and the metal branches of the second portion 30" form a ring current and induce a magnetic field to adjust the relative magnetic permeability of the metamaterial.
  • a synthetic metal microstructure can be attached to the substrate to meet the design requirements.
  • the substrate and the process of attaching the artificial metal microstructure to the substrate are the same as those of the first preferred embodiment and will not be described again.
  • Fig. 7 is a computer simulation effect view of the artificial metal microstructure 30 of the preferred embodiment attached to one surface of the substrate.
  • S n is used to indicate the reflection coefficient of the material, that is, the impedance matching characteristic
  • S 21 is used to indicate the transmission coefficient, that is, the attenuation characteristic of the material.
  • S n has a distinct absorption peak near 17 GHz, and S 21 can be less than -15 dB in the vicinity of a large bandwidth, that is, impedance matching characteristics and attenuation characteristics are good, and electromagnetic wave absorption can be achieved.
  • a three-dimensional man-made metal microstructure is adopted, and its unique topological structure design enables the artificial microstructure to generate the same electromagnetic response to both the electric field and the magnetic field of electromagnetic waves in any incident direction, and thus any incident direction.
  • the electromagnetic wave can be absorbed by the absorbing wave metamaterial, which greatly improves the practical range of the absorbing wave metamaterial, and is described in detail below:
  • FIG. 9 is a schematic diagram of a three-dimensional three-dimensional structure of the artificial metal microstructure according to the embodiment, which is formed by three planar topographic patterns shown in FIG. 8 intersecting perpendicularly at a common center point in a three-dimensional space.
  • the planar topographic pattern includes two first metal branches that intersect each other perpendicularly in a "ten" shape.
  • the relative dielectric constant ⁇ of the metamaterial can be adjusted by adjusting the area S and the spacing d of the metal branches having the spacing; the plane corresponding to the polarization direction of the electromagnetic wave is equivalent to the inductive component and forming a ring current thereon.
  • the ring current generates a magnetic field to affect the relative magnetic permeability ⁇ of the metamaterial.
  • the two-dimensional topological pattern shown in FIG. 8 is regarded as a planar topology of the artificial metal microstructure of the present invention.
  • the planar topology The electromagnetic wave whose pattern is responsive to any incident direction perpendicular to the plane in the three-dimensional space can be equally divided into a plurality of topologies as shown in FIGS. 10 and 11.
  • Figure 10 shows the topology of the planar topology in response to the electric field.
  • Figure 11 shows the topology of the planar topology in response to the magnetic field.
  • the topological structure split in Figure 10 consists of three categories: (1) two pairs of second metal branches 102,
  • the planar topology in FIG. 11 is split into a plurality of open annular metal branches, and is mainly composed of two types: (1) a first metal branch 101, a third metal branch 103, and a first metal branch 101 and a third metal branch 103 connected thereto. Part of the second metal branch 102, (2) the fourth metal branch 104. It can be seen from FIG. 10 and FIG. 11 that, due to the special topology design of the present invention, when the electromagnetic wave in the arbitrary direction of the three-dimensional space perpendicular to the planar topology is passed through the metamaterial, the metamaterial can be adjusted by the artificial metal microstructure.
  • the area and/or length of the metal branches adjust the relative dielectric constant and relative permeability of the bulk material as a whole.
  • the overall artificial microstructure of the present invention consists of three identical The planar topology is formed by perpendicularly intersecting two points in the three-dimensional space. Therefore, the artificial metal microstructure of the present invention can adjust the relative dielectric constant and relative magnetic permeability of the electromagnetic wave in any three-dimensional space.
  • the relationship between the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ of the supermaterial and the electromagnetic wave frequency f is shown in Fig. 5 and Fig. 6.
  • Fig. 5 and Fig. 6 we can find that the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ are small at a distance away from the resonance frequency, so the adjustment of the artificial metal microstructure metal size changes the relative dielectric constant ⁇ and The effect of the relative magnetic permeability ⁇ is also very small.
  • the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ both change exponentially. At this time, adjusting the artificial metal microstructure metal size will greatly affect the relative dielectric constant ⁇ and relative of the supermaterial.
  • the magnetic permeability ⁇ can thus achieve the impedance matching requirement of the present invention, that is, the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ at one frequency band are equal. Therefore, the electromagnetic wave frequency band required by the present invention is generally a frequency band which deviates from the resonance frequency of the artificial metal microstructure and which causes the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ to be exponentially attenuated.
  • this paragraph is only for describing the regularity of the experiment in the present invention, and is not intended to limit the electromagnetic wave incident frequency band of the present invention.
  • the relative dielectric constant ⁇ of the metamaterial and the relative magnetic permeability ⁇ are substantially equal to satisfy the design requirement of the impedance matching of the present invention.
  • the term "substantially equal” means that the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ have only errors that do not affect the impedance matching effect.
  • the energy loss is mainly characterized by the electrical loss factor tan S e and the magnetic loss factor tan S m . Different substrates correspond to different main losses.
  • ferroelectric materials are mainly electrical losses
  • ferromagnetic materials are mainly magnetic losses
  • ferrite The materials are both.
  • the effect of the artificial metal microstructure on the overall attenuation characteristics of the metamaterial is to improve the attenuation characteristics of the substrate by improving the attenuation characteristics of the substrate, that is, increasing the imaginary part of the overall relative dielectric constant and/or relative permeability of the supermaterial. It can be understood that the process of adjusting the size of the artificial metal microstructure so that the metamaterial satisfies the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ and the improvement of the attenuation characteristic of the substrate is interactive, and is not based on the adjustment of a condition. Adjust the second condition on.
  • FIG. 12 is a plan view showing a three-dimensional structure of a man-made metal microstructure in a fourth preferred embodiment of the absorbing wave metamaterial of the present invention; Derived graph of a two-dimensional topological pattern.
  • the difference from the third preferred embodiment is that the two ends of the notch 1041 further extend inwardly with two opposite fifth metal branches 105.
  • the fifth metal branch 105 adds one type of equivalent capacitive elements formed by the artificial microstructures to electromagnetic waves incident in all directions of the three-dimensional space, and changes the open annular current distribution in the fourth metal branch 104. It is easier to achieve the object of the present invention by increasing the parameter of adjusting the relative dielectric constant ⁇ and the relative magnetic permeability ⁇ of the entire metamaterial by one.
  • the substrate may be selected from materials having high energy loss such as high molecular polymers, ceramics, polytetrafluoroethylene, ferroelectric materials, ferrite materials or ferromagnetic materials.
  • the substrate generally adopts a sheet-like structure, and each of the sheet-like substrates has a plurality of artificial metal microstructures, a plurality of sheet-like substrates, attached to one of the two opposite side surfaces or each of the opposite side surfaces according to design requirements.
  • the gapless superposition is tightly combined to form a whole.
  • etching is a superior manufacturing process, and the steps are in design.
  • a metal foil is integrally attached to the substrate, and then the chemical reaction of the solvent and the metal is used to remove the artificial metal microstructure preset pattern by etching equipment.
  • the remaining man-made metal microstructures are arranged in the array.
  • the material of the above metal foil may be any metal such as copper or silver.

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Abstract

本发明涉及一种吸波超材料，其包括具有两相对侧表面的基材，该两相对侧表面至少一侧表面上附着有周期排列的多个人造金属微结构；当入射方向垂直于该基材两相对侧表面的电磁波通过该超材料时该超材料的相对介电常数和相对磁导率基本相等。本发明采用不同于传统吸波材料的吸波原理，通过将各种人造金属微结构周期排列于基材上并调整该人造金属微结构以达到理想吸波效果，其具有质量轻、厚度薄且电磁参数易于调节的优点。

Description

一种吸波超材料
【技术领域】
本发明涉及一种吸波材料， 尤其涉及一种吸波超材料。 【背景技术】
吸波材料是指能够吸收和衰减入射电磁波能量， 通过材料的介质损耗使其电 磁能转换成热能或其他能量形式的一类功能复合材料。 吸波材料在治理电磁污 染、 制造隐身材料等方面具有巨大的应用前景。
目前常用的吸波材料有铁氧体、 钛酸钡、 金属微粉、 石墨、 碳化硅、 导电纤 维等， 其中又已铁氧体吸波材料是研究将多且比较成熟的吸波材料。 铁氧体在 高频下有较高的磁导率和电阻率， 电磁波易于进入并能快速衰减。 但是， 以铁 氧体为代表的此类吸波材料存在高温特性差、 面密度大且电磁参数匹配困难等 缺陷。
【发明内容】
本发明要解决的技术问题在于针对现有技术的上述不足， 提出一种吸波性能 好、 质量轻、 厚度薄且电磁参数易于调节的吸波超材料。
本发明解决其技术问题所采用的技术方案是提出一种吸波超材料， 其包括基 材、 周期排列于该基材内部的多个人造金属微结构； 当电磁波通过该超材料时 该超材料的相对介电常数和相对磁导率大致相等。
当该电磁波通过该超材料时该超材料的相对介电常数和 /或相对磁导率的虚 部大于该基材的相对介电常数和 /或相对磁导率的虚部使得该电磁波被吸收。
该吸波超材料包括具有两相对侧表面的基材， 该两相对侧表面至少一侧表面 上附着有周期排列的多个人造金属微结构； 当入射方向垂直于该基材两相对侧 表面的电磁波通过该超材料时该超材料的相对介电常数和相对磁导率基本相等。
当入射方向垂直于该基材两相对侧表面的电磁波通过该超材料时该超材料 的相对介电常数的虚部和 /或相对磁导率的虚部大于该基材的相对介电常数的 虚部和 /或相对磁导率的虚部使得该电磁波被吸收。
该基材两相对侧表面的一侧表面上附着有第一人造金属微结构， 另一侧表面 上附着有与该第一人造金属微结构一一对应的第二人造金属微结构； 该第一人 造金属微结构包括相互垂直而连接成 "十"字形的两个第一金属分支， 分别连 接在该第一金属分支两端且垂直于该第一金属分支的第二金属分支； 该第二人 造金属微结构由一边具有缺口的四边形状的第三金属分支构成。
该第一人造金属微结构的每个该第二金属分支的中点分别设于与其连接的 该第一金属分支的端点； 该第二人造金属微结构由一边中点具有缺口的正方形 状的该第三金属分支构成。
该人造金属微结构包括第一金属分支， 该第一金属分支构成一边具有缺口的 四边形状； 一端设于该缺口相对的四边形边上并向该缺口延伸且突出该缺口的 第二金属分支； 垂直于该第二金属分支另一端的第三金属分支。
该人造金属微结构以该第二金属分支为对称轴成左右对称结构。
该基材为片状基材， 该超材料由附着有多个该人造金属微结构的该片状基材 叠加而成。
该人造金属微结构由三个相同的平面拓扑结构在三维空间共中心点两两垂 直相交而成。
该平面拓扑结构包括： 相互垂直相交呈 "十"字形的两条第一金属分支； 分 别连接于该两条第一金属分支两端、 长度小于该第一金属分支并垂直于该第一 金属分支的四条第二金属分支； 从该第二金属分支两端向内延伸的八条第三金 属分支； 一边具有缺口并设置于该四条第二金属分支围成的平面内的四边形状 的第四金属分支， 该第四金属分支的四边长度小于该第二金属分支且具有该缺 口的一边不与该第一金属分支相交， 其他三边均与该第一金属分支相交。
该平面拓扑结构还包括从该缺口两端向内延伸的两条第五金属分支。
该第三金属分支与与其相连的该第二金属分支形成的角度为 45 ° 。 该第四金属分支中心点与两条该第一金属分支交点重合。
该基材由多个片状基材组合而成， 每一片状基材上附着有多个金属分支； 当 多个该片状基材组合后， 附着在多个该片状基材上的多个该金属分支组合为该 人造金属微结构。
该基材为高分子聚合物、 陶瓷、 铁电材料、 铁氧材料或铁磁材料。
周期排列的多个该人造金属微结构是通过蚀刻、电镀、钻刻、光刻、电子刻、 离子刻附着于该基材两相对侧表面至少一侧表面上。
本发明采用不同于传统吸波材料的吸波原理， 通过将各种人造金属微结构周 期排列于基材上并调整该人造金属微结构的尺寸以达到理想吸波效果， 其具有 质量轻、 厚度薄、 受外部环境干扰小且电磁参数易于调节的优点。 进一歩地， 本发明的人造金属微结构可为三维结构， 其对三维空间任意入射方向的电磁波 均能有效吸收， 提高了吸波超材料的实用性。 更进一歩地， 本发明采用片状基 材组合成整体基材的方法来构成超材料， 使得超材料内部人造金属微结构的尺 寸和间隔均可分别地方便地调节即本发明超材料的相对介电常数和相对磁导率 调节方便。
【附图说明】
为了更清楚地说明本发明实施例中的技术方案， 下面将对实施例描述中所 需要使用的附图作简单地介绍， 显而易见地， 下面描述中的附图仅仅是本发明 的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下， 还可以根据这些附图获得其他的附图。 其中：
图 1是本发明吸波超材料第一较佳实施例中附着于基材一侧表面的第一人造 金属微结构图；
图 2是本发明吸波超材料第一较佳实施例中附着于基材另一侧表面的第二人 造金属微结构图；
图 3是本发明吸波超材料第二较佳实施例中人造金属微结构图；
图 4是本发明吸波超材料第二较佳实施例中人造金属微结构对入射电磁波电 场和磁场响应的分解原理图；
图 5是本发明吸波超材料相对介电常数 ε 与电磁波频率 f 的 ε -f关系示意 图；
图 6是本发明吸波超材料相对磁导率 μ与电磁波频率 f的 μ -f关系示意图； 图 7是本发明吸波超材料第二较佳实施例中人造金属微结构被附着在基材一 侧表面的计算机仿真效果图；
图 8是本发明吸波超材料第三较佳实施例中人造金属微结构立体结构的平面 拓扑图；
图 9是本发明吸波超材料第三较佳实施例中人造金属微结构立体结构示意图; 图 10 是本发明吸波超材料第三较佳实施例中人造金属微结构平面拓扑图对 应三维空间垂直于该平面入射的电磁波而拆分的可对电场响应的多个等效拓扑 图；
图 11 是本发明吸波超材料第三较佳实施例中人造金属微结构平面拓扑图对 应三维空间垂直于该平面入射的电磁波而拆分的可对磁场响应的多个等效拓扑 图；
图 12 是本发明吸波超材料第四较佳实施例中人造金属微结构立体结构平面 拓扑图的衍生图。
【具体实施方式】
吸波材料的基本物理原理是材料对入射电磁波实现有效吸收， 将电磁波能 量转换为热能或其他形式的能量而耗散掉， 该材料应具备两个特性即阻抗匹配 特性和衰减特性。 阻抗匹配特性是指从自由空间入射到吸波材料表面的电磁波 被吸波材料表面反射而形成的反射特性。 理想的吸波材料要达到完美阻抗匹配 特性时应使得从自由空间入射的电磁波在理想吸波材料表面形成零反射， 即电 磁波全部进入理想吸波材料内部。由于自由空间阻抗 ζ=ι，根据公式 ζ= β可知， 当该吸波材料的相对介电常数 ε和相对磁导率 μ相等时即可达到理想阻抗匹配 特性。 其中由于吸波材料存在损耗， 所以相对介电常数 ε=ε'-」ε"，相对磁导率 μ=μ'-]μ 衰减特性是指进入材料内部 电磁波产生损耗而被吸收的现象， 损耗 大小可用电损耗因子 tan δ ε=ε"/ε'和磁损耗因子 tan δ πι=μ"/μ'来表征。既满足阻 抗匹配特性又满足尽可能大的衰减特性是各类吸波材料追求的目标。 超材料是由具有一定图案形状的人造金属微结构按照特定方式周期排列于 基材中而构成。 每一人造金属微结构和其所附着的基材构成了超材料的基本单 元， 多个超材料基本单元按一定规律排列即可使得超材料对电磁波具有宏观的 响应。 由于超材料整体需对入射电磁波有宏观电磁响应因此各个超材料基本单 元对入射电磁波的响应需形成连续响应， 这要求每一超材料基本单元的尺寸小 于入射电磁波波长的五分之一， 优选为入射电磁波波长的十分之一。 本段描述 中， 我们人为的将超材料整体划分为多个超材料基本单元， 但应知此种划分方 法仅为描述方便， 不应看成超材料由多个超材料基本单元拼接或组装而成， 实 际应用中超材料是将人造金属微结构周期排布于基材上即可构成， 工艺简单且 成本低廉。 周期排布即指上述我们人为划分的各个超材料基本单元上的人造金 属微结构能对入射电磁波产生连续的电磁响应。
改变每一超材料基本单元上的人造金属微结构的图案形状或尺寸使得超材 料具有不同的介电常数和不同的磁导率从而使得超材料具有不同的电磁响应。
本发明利用超材料上述原理设计一种能强烈吸收特定频段电磁波的超材料。 该超材料包括具有两相对侧表面的基材， 在该两相对侧表面的至少一侧表面上 附着有多个周期排列的人造金属微结构。 当基材表面未附着人造金属微结构时， 其对电磁场表现出具有初始相对介电常数 ει和初始相对磁导率 μ1 ; 当基材表面 附着有人造金属微结构后， 人造金属微结构会对入射电磁场产生响应从而使得 基材和人造金属微结构整体构成一种超材料， 超材料对电磁场的响应会因人造 金属微结构尺寸的变化而变化， 即超材料的相对介电常数 ε和相对磁导率 μ会 因人造金属微结构尺寸的变化而变化。 当超材料用作吸波材料时， 需要结合基 材的初始相对介电常数 ει和初始相对磁导率 μι设计初始人造金属结构的拓扑图 案和尺寸使之达到吸波材料的设计要求， 即阻抗匹配特性和衰减特性均十分优 良。 因为人造金属微结构需对入射电磁波的电场和磁场均产生响应， 因此人造 金属微结构所在平面必须存在电场和磁场分量， 根据电磁场理论， 当电磁波入 射方向垂直于人造金属微结构所在表面时即可满足要求。 并且为了更好的满足 衰减特性的要求， 本发明的基材采用对电磁波损耗大的各类常见材料， 例如高 分子聚合物、 陶瓷、 铁电材料、 铁氧材料或铁磁材料等， 其中高分子聚合物优 选 FR- 4或 F4B材料。
请参阅图 1至图 7，下面结合对几种人造金属微结构拓扑图案详细说明本发 明设计原理。
本发明第一较佳实施例中， 在基材两相对侧表面附着有不同的两种人造金 属微结构， 如图 1和图 2所示。 基材一侧表面的第一人造金属微结构 10包括相 互垂直而连接成 "十"字形的两个第一金属分支 11， 分别连接在每个第一金属 分支 11两端且垂直于第一金属分支 11的第二金属分支 12。 基材另一侧表面的 第二人造金属微结构 20包括第三金属分支 201， 该第三金属分支 201构成一边 具有缺口 2011的四边形状。 该两个人造金属微结构在基材两相对侧表面一一对 应。 优选地， 第一人造金属微结构 10的第二金属分支 12中点分别设于其所连 接的该第一金属分支 11的端点， 第二人造金属微结构 20 由一边中点具有缺口
2011的正方形状的第三金属分支 201构成。
当入射方向垂直于基材两相对侧表面的电磁波该超材料时， 第一人造金属 微结构 10的第二金属分支 12分别聚集正负电子形成等效容性元件。根据公式8= ε S d
4πκα 可知， 其中 为超材料相对介电常数、 为第二金属分支面积、 为第二金 属分支间隔、 k为常数、 C为等效电容量， 超材料的相对介电常数 ε可通过调整 第二金属分支 12的面积 S与第二金属分支 12的间距 d来调整， 第二金属分支 12的间距 d即为第一金属分支 11的长度； 第二人造金属微结构 20的第三金属 分支 201 上形成环形电流， 根据右手螺旋定则， 环形电流产生磁场从而影响超 材料的相对磁导率 μ。 分别调节第一人造金属微结构 10和第二人造金属微结构 20 的金属分支的尺寸和间隔即可调节人造金属微结构对入射电场和入射磁场的 响应从而调节超材料整体的相对介电常数 ε和相对磁导率 μ。 超材料整体的相对介电常数 ε和相对磁导率 μ的与电磁波频率 f 的关系图 如图 5、 图 6所示。 在图 5和图 6中我们可以发现， 相对介电常数 ε和相对磁导 率 μ在远离谐振频点处， 其变化是微小的， 因此调整人造金属微结构金属尺寸 改变相对介电常数 ε和相对磁导率 μ所起到的作用也十分微小。 但是在接近谐 振频点的频段处， 相对介电常数 ε和相对磁导率 μ均成指数变化， 此时调整人 造金属微结构金属尺寸将极大影响超材料整体的相对介电常数 ε和相对磁导率 μ， 因此可以达到本发明的阻抗匹配要求，即一频段处相对介电常数 ε和相对磁导率 μ相等。 因此， 本发明所需的电磁波频段通常为偏离人造金属微结构谐振频点且 可使相对介电常数 ε和相对磁导率 μ成指数衰减的频段。 当然， 此段说明仅为 描述本发明实验过程中的规律， 并非用以限定本发明电磁波入射频段。
当人造金属微结构的尺寸使得具有一频段的入射电磁波通过超材料时， 超 材料的相对介电常数 ε和相对磁导率 μ基本相等时即满足本发明阻抗匹配的设 计要求。 所谓基本相等是指相对介电常数 ε和相对磁导率 μ只存在不影响阻抗 匹配效果的误差。 同时， 为了达到优良的吸波性能还需要继续调整人造金属微 结构的尺寸使超材料对入射电磁波有最大的能量损耗。 能量损耗主要是通过电 损耗因子 tan δ e和磁损耗因子 tan δ m来表征，不同的基材对应不同的主要损耗 因子， 例如铁电材料主要为电损耗因子、 铁磁材料主要为磁损耗因子而铁氧材 料则两者皆有。 人造金属微结构对超材料整体衰减特性的影响是通过改善基材 的衰减特性即提高超材料整体的相对介电常数和 /或相对磁导率的虚部从而提 高超材料整体的衰减特性。 可以理解的， 调整人造金属微结构的尺寸使超材料 满足相对介电常数 ε和相对磁导率 μ基本相等以及改善基材衰减特性的过程是 交互的， 并非调整完一个条件以后再在原有基础上调整第二个条件。
图 3为本发明第二较佳实施例的人造金属微结构图。 该人造金属微结构 30 包括第一金属分支 301， 该第一金属分支 301构成一边具有缺口 3011的四边形 状； 一端设于缺口 3011相对的四边形边上并向缺口 3011延伸且突出缺口 3011 的第二金属分支 302; 垂直于第二金属分支 302另一端的第三金属分支 303。 人 造金属微结构 30附着于基材两相对侧表面其中之一表面上， 优选地， 为了取得 更好的吸波效果在基材两相对侧表面上均附着有人造金属微结构 30且两相对侧 表面的人造金属微结构成镜像对称， 更优选地， 每一侧表面的人造金属微结构 30以第二金属分支 302为对称轴成左右对称结构。
本较佳实施例中人造金属微结构 30相当于结合了第一较佳实施例中的第一 人造金属微结构 10和第二人造金属微结构 20，其对垂直入射的电磁波的电磁响 应原理与第一较佳实施例相同， 即相对的金属分支等效为电容元件从而调整超 材料的相对介电常数 ε，环形金属分支上感生的电流根据右手螺旋定则感生磁场 从而调整超材料的相对磁导率 。 具体到本实施例可表现为， 如图 4所示， 人造 金属微结构 30拆分为呈 "工"字形的第一部分 30'以及呈一边缺口的四边形状 的第二部分 30"， 第一部分 30'的金属分支分别聚集正负电荷形成等效容性元件 从而调整超材料的相对介电常数，第二部分 30"的金属分支形成环形电流并感生 磁场从而调整超材料的相对磁导率。 同时， 由于本较佳实施例对人造金属微结 构独特的图案设计使得基材上附着一面人造金属微结构即可满足设计要求。
基材以及在基材上附着人造金属微结构的工艺与第一较佳实施例相同， 在 此不再赘述。
图 7为本较佳实施例的人造金属微结构 30被附着在基材一侧表面的计算机 仿真效果图。 在计算机仿真中， 用 Sn表示材料的反射系数即阻抗匹配特性， 用 S21表示材料的透射系数即衰减特性。 在图 5中可以看出， 在 17GHZ附近 Sn有明 显吸收峰， S21在很大带宽附近都能小于 -15dB，即阻抗匹配特性和衰减特性都较 好， 能实现电磁波的吸收。
在本发明的另一实施例中， 采用立体的人造金属微结构， 其独特的拓扑结 构设计使得人造微结构对任意入射方向的电磁波的电场和磁场均能产生相同的 电磁响应， 因此任意入射方向的电磁波通过该吸波超材料时均能被吸收， 极大 地提高了该吸波超材料的实用范围， 下面进行详细描述：
请参阅图 5、 图 6以及图 8至图 12， 下面对几种人造金属微结构拓扑图案 对本发明进行详细说明： 请参照图 8和图 9。 图 9为本实施例人造金属微结构三维立体结构示意图， 其由三个图 8所示的平面拓扑图案在三维空间共中心点两两垂直相交而成。 如 图 8所示， 平面拓扑图案包括相互垂直相交呈 "十"字形的两条第一金属分支
101； 分别连接于两条第一金属分支 101两端， 长度小于第一金属分支 101并垂 直于第一金属分支 101的四条第二金属分支 102;从第二金属分支 102两端以相 同角度向内延伸的八条第三金属分支 103; —边具有缺口 1041并设置于第二金 属分支 102围成的平面内的四边形状的第四金属分支 104，第四金属分支 104的 四边长度小于第二金属分支 102， 具有缺口 1041的一边不与第一金属分支 101 相交， 其他三边均与第一金属分支 101相交。
当三维空间任意入射方向的电磁波通过该超材料时， 电磁波的电场方向对 应的平面的金属分支之间的间隔等效为容性元件。根据公式8=
4πκα 可知，超材 料的相对介电常数 ε可通过调整具有间隔的金属分支的面积 S以及间距 d来调整; 电磁波的磁场极化方向对应的平面整体等效为感性元件并在其上形成环形电流， 根据右手螺旋定则， 环形电流产生磁场从而影响超材料的相对磁导率 μ。
具体到本实施例中， 将图 8所示的二维拓扑图案看作为本发明人造金属微 结构其中的一个平面拓扑结构， 当入射方向垂直于该平面的电磁波通过该超材 料时， 该平面拓扑图案响应三维空间垂直于该平面的任意入射方向的电磁波可 等效拆分为如图 10和图 11所示的多个拓扑结构。 其中图 10为平面拓扑结构响 应电场而拆分的多个拓扑结构， 图 11为平面拓扑结构响应磁场而拆分的多个拓 扑结构。 图 10中被拆分的拓扑结构是由三类组成： （1 )两对第二金属分支 102，
(2) 四队第三金属分支 103， (3)缺口 1041相对的第二金属分支 102以及缺口
1041相对的对边 1042。 图 11中平面拓扑结构拆分为多个开口环形金属分支， 主要由两类组成： （1 )第一金属分支 101、 第三金属分支 103以及连接第一金属 分支 101和第三金属分支 103的部分第二金属分支 102，（2 )第四金属分支 104。 从图 10和图 11中可以看出， 由于本发明特殊的拓扑结构设计使得入射方向为 三维空间垂直于平面拓扑结构任意方向的电磁波通过超材料时， 超材料都可以 通过调整人造金属微结构各个金属分支的面积和 /或长度来调整超材料整体的 相对介电常数和相对磁导率。 进一歩地， 本发明整体人造微结构由三个相同的 该平面拓扑结构在三维空间两两共交点垂直相交而成， 因此本发明人造金属微 结构对应三维空间任意入射方向的电磁波均可调整其相对介电常数和相对磁导 率。
超材料整体的相对介电常数 ε和相对磁导率 μ的与电磁波频率 f 的关系图 如图 5、 图 6所示。 在图 5和图 6中我们可以发现， 相对介电常数 ε和相对磁导 率 μ在远离谐振频点处， 其变化是微小的， 因此调整人造金属微结构金属尺寸 改变相对介电常数 ε和相对磁导率 μ所起到的作用也十分微小。 但是在接近谐 振频点的频段处， 相对介电常数 ε和相对磁导率 μ均成指数变化， 此时调整人 造金属微结构金属尺寸将极大影响超材料整体的相对介电常数 ε和相对磁导率 μ， 因此可以达到本发明的阻抗匹配要求，即一频段处相对介电常数 ε和相对磁导率 μ相等。 因此， 本发明所需的电磁波频段通常为偏离人造金属微结构谐振频点且 可使相对介电常数 ε和相对磁导率 μ成指数衰减的频段。 当然， 此段说明仅为 描述本发明实验过程中的规律， 并非用以限定本发明电磁波入射频段。
当人造金属微结构的尺寸使得具有一频段的入射电磁波通过超材料时， 超 材料的相对介电常数 ε和相对磁导率 μ大致相等时即满足本发明阻抗匹配的设 计要求。 所谓大致相等是指相对介电常数 ε和相对磁导率 μ只存在不影响阻抗 匹配效果的误差。 同时， 为了达到优良的吸波性能还需要继续调整人造金属微 结构的尺寸使超材料对入射电磁波有最大的能量损耗。 能量损耗主要是通过电 损耗因子 tan S e和磁损耗因子 tan S m来表征，不同的基材对应不同的主要损耗， 例如铁电材料主要为电损耗、 铁磁材料主要为磁损耗而铁氧材料则两者皆有。 人造金属微结构对超材料整体衰减特性的影响是通过改善基材的衰减特性， 即 提高超材料整体相对介电常数和 /或相对磁导率的虚部从而提高超材料整体的 衰减特性。 可以理解的， 调整人造金属微结构的尺寸使超材料满足相对介电常 数 ε和相对磁导率 μ大致相等以及改善基材衰减特性的过程是交互的， 并非调 整完一个条件以后再在原有基础上调整第二个条件。
图 12为本发明吸波超材料第四较佳实施例中人造金属微结构立体结构平面 二维拓扑图案的衍生图。 其与第三较佳实施例的不同点在于， 缺口 1041两端还 向内延伸有两条相对的第五金属分支 105。第五金属分支 105使得人造微结构对 应三维空间各方向入射的电磁波形成的等效容性元件增加一类， 并改变第四金 属分支 104中开口环形电流分布。使得调整整个超材料相对介电常数 ε和相对磁 导率 μ的参数增加一个， 更容易实现本发明目的。
基材可选取高分子聚合物、 陶瓷、 聚四氟乙烯、 铁电材料、 铁氧材料或铁 磁材料等能量损耗大的材料。
基材通常采用片状结构， 每个片状基材根据设计要求在两相对侧表面其中 之一表面上或两相对侧表面每一表面上附着多个人造金属微结构， 多个片状基 材无间隙的叠加而紧密结合构成一个整体。
在基材表面上附着人造金属微结构的制造工艺有多种， 例如蚀刻、 电镀、钻刻、 光刻、 电子刻、 离子刻等， 其中蚀刻是较优的制造工艺， 其歩骤是在设计好合 适的人造金属微结构的平面图案后， 先将一张金属箔片整体地附着在基材上， 然后通过蚀刻设备， 利用溶剂与金属的化学反应去除掉人造金属微结构预设图 案以外的箔片部分， 余下的即可得到阵列排布的人造金属微结构。 上述金属箔 片的材质可以是铜、 银等任何金属。
上面结合附图对本发明的较佳实施例进行了描述， 但是本发明并不局限于 上述的具体实施方式，上述的具体实施方式仅仅是示意性的，而不是限制性的， 本领域的普通技术人员在本发明的启示下， 在不脱离本发明宗旨和权利要求所 保护的范围情况下， 还可做出很多形式， 这些均属于本发明的保护之内。

Claims

权 利 要 求
1、 一种吸波超材料， 其特征在于： 所述吸波超材料包括基材、 周期排列于 该基材内部的多个人造金属微结构； 当电磁波通过该超材料时该超材料的相对 介电常数和相对磁导率大致相等。
2、 如权利要求 1所述的吸波超材料， 其特征在于： 当该电磁波通过该超材 料时该超材料的相对介电常数和 /或相对磁导率的虚部大于该基材的相对介电 常数和 /或相对磁导率的虚部使得该电磁波被吸收。
3、 如权利要求 2所述的吸波超材料， 其特征在于： 所述吸波超材料包括具 有两相对侧表面的基材， 该两相对侧表面至少一侧表面上附着有周期排列的多 个人造金属微结构； 当入射方向垂直于该基材两相对侧表面的电磁波通过该超 材料时该超材料的相对介电常数和相对磁导率基本相等。
4、 如权利要求 3所述的吸波超材料， 其特征在于： 当入射方向垂直于该基 材两相对侧表面的电磁波通过该超材料时该超材料的相对介电常数的虚部和 / 或相对磁导率的虚部大于该基材的相对介电常数的虚部和 /或相对磁导率的虚 部使得该电磁波被吸收。
5、 如权利要求 4所述的吸波超材料， 其特征在于： 该基材两相对侧表面的 一侧表面上附着有第一人造金属微结构， 另一侧表面上附着有与该第一人造金 属微结构一一对应的第二人造金属微结构； 该第一人造金属微结构包括相互垂 直而连接成 "十"字形的两个第一金属分支， 分别连接在该第一金属分支两端 且垂直于该第一金属分支的第二金属分支； 该第二人造金属微结构由一边具有 缺口的四边形状的第三金属分支构成。
6、 如权利要求 5所述的吸波超材料， 其特征在于： 该第一人造金属微结构 的每个该第二金属分支的中点分别设于与其连接的该第一金属分支的端点； 该 第二人造金属微结构由一边中点具有缺口的正方形状的该第三金属分支构成。
7、 如权利要求 3所述的吸波超材料， 其特征在于： 该人造金属微结构包括 第一金属分支， 该第一金属分支构成一边具有缺口的四边形状； 一端设于该缺 口相对的四边形边上并向该缺口延伸且突出该缺口的第二金属分支； 垂直于该 第二金属分支另一端的第三金属分支。
8、 如权利要求 7所述的吸波超材料， 其特征在于： 该人造金属微结构以该 第二金属分支为对称轴成左右对称结构。
9、 如权利要求 3所述的吸波超材料， 其特征在于： 该基材为片状基材， 该 超材料由附着有多个该人造金属微结构的该片状基材叠加而成。
10、 如权利要求 2所述的吸波超材料， 其特征在于： 该人造金属微结构由 三个相同的平面拓扑结构在三维空间共中心点两两垂直相交而成。
11、如权利要求 10所述的吸波超材料，其特征在于：该平面拓扑结构包括： 相互垂直相交呈 "十"字形的两条第一金属分支； 分别连接于该两条第一金属 分支两端、 长度小于该第一金属分支并垂直于该第一金属分支的四条第二金属 分支； 从该第二金属分支两端向内延伸的八条第三金属分支； 一边具有缺口并 设置于该四条第二金属分支围成的平面内的四边形状的第四金属分支， 该第四 金属分支的四边长度小于该第二金属分支且具有该缺口的一边不与该第一金属 分支相交， 其他三边均与该第一金属分支相交。
12、 如权利要求 11所述的吸波超材料， 其特征在于： 该平面拓扑结构还包 括从该缺口两端向内延伸的两条第五金属分支。
13、 如权利要求 11所述的吸波超材料， 其特征在于： 该第三金属分支与与 其相连的该第二金属分支形成的角度为 45 ° 。
14、 如权利要求 11所述的吸波超材料， 其特征在于： 该第四金属分支中心 点与两条该第一金属分支交点重合。
15、 如权利要求 1 所述的吸波超材料， 其特征在于： 该基材由多个片状基 材组合而成，每一片状基材上附着有多个金属分支；当多个该片状基材组合后， 附着在多个该片状基材上的多个该金属分支组合为该人造金属微结构。
16、 如权利要求 1 所述的吸波超材料， 其特征在于： 该基材为高分子聚合 物、 陶瓷、 铁电材料、 铁氧材料或铁磁材料。
17、 如权利要求 1 所述的吸波超材料， 其特征在于： 周期排列的多个该人 造金属微结构是通过蚀刻、 电镀、 钻刻、 光刻、 电子刻、 离子刻附着于该基材 两相对侧表面至少一侧表面上。
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EP2693860B1 (en) 2017-04-19

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