WO2012126249A1 - 一种实现电磁波偏折的超材料 - Google Patents

一种实现电磁波偏折的超材料 Download PDF

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Publication number
WO2012126249A1
WO2012126249A1 PCT/CN2011/082392 CN2011082392W WO2012126249A1 WO 2012126249 A1 WO2012126249 A1 WO 2012126249A1 CN 2011082392 W CN2011082392 W CN 2011082392W WO 2012126249 A1 WO2012126249 A1 WO 2012126249A1
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WIPO (PCT)
Prior art keywords
metamaterial
electromagnetic wave
refractive index
gradually
wave deflection
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PCT/CN2011/082392
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English (en)
French (fr)
Inventor
刘若鹏
徐冠雄
栾琳
季春霖
赵治亚
李岳峰
岳玉涛
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 201110066154 external-priority patent/CN102480057B/zh
Priority claimed from CN201110081021.7A external-priority patent/CN102738592B/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 EP11854537.5A priority Critical patent/EP2688149B1/en
Priority to US13/522,017 priority patent/US9198334B2/en
Publication of WO2012126249A1 publication Critical patent/WO2012126249A1/zh

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    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
    • H01Q15/0086—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials
    • 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
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
    • H05K1/0236—Electromagnetic band-gap structures
    • 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
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0237—High frequency adaptations
    • H05K1/024—Dielectric details, e.g. changing the dielectric material around a transmission line
    • 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
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/09—Shape and layout
    • H05K2201/09818—Shape or layout details not covered by a single group of H05K2201/09009 - H05K2201/09809
    • H05K2201/09972—Partitioned, e.g. portions of a PCB dedicated to different functions; Boundary lines therefore; Portions of a PCB being processed separately or differently
    • 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
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/46—Manufacturing multilayer circuits
    • H05K3/4688—Composite multilayer circuits, i.e. comprising insulating layers having different properties
    • H05K3/4694—Partitioned multilayer circuits having adjacent regions with different properties, e.g. by adding or inserting locally circuit layers having a higher circuit density

Definitions

  • the present invention relates to the field of electromagnetic communication, and more particularly to a metamaterial that achieves electromagnetic wave deflection. ⁇ Background technique ⁇
  • the communication field mainly relies on electromagnetic waves for detection, positioning, and communication. Electromagnetic waves can be separated, concentrated, deflected, diverged, etc. by different materials or components.
  • a material that can achieve electromagnetic wave deflection even if the direction of propagation of the electromagnetic wave changes is mainly a non-uniform material, that is, a material that is heterogeneous and causes an uneven distribution of the refractive index. Different materials, different materials, etc. will change the distribution of refractive index.
  • Non-uniform materials used in the prior art for deflecting electromagnetic waves are generally formed by stacking multiple layers of materials having different refractive indices. According to the characteristics of the frequency, wavelength and the like of the electromagnetic wave to be deflected, the refractive index distribution of the non-uniform material can be designed, and then a suitable material having a corresponding refractive index is selected in each distribution region.
  • a disadvantage of such a material that deflects electromagnetic waves is that the refractive index of the existing material is inherent and cannot be arbitrarily designed. When the refractive index of a portion of the desired refractive index distribution is not available with existing natural materials. Will result in the entire non-uniform material not meeting the required deflection requirements.
  • Metamaterials are artificial composite structures or composites that have extraordinary physical properties not found in natural materials. Through the orderly design of the structure at the key physical scale of the material, it is possible to break through the limitations of certain apparent natural laws, thereby obtaining the functions of ordinary metamaterials beyond the natural ones.
  • conventional metamaterials mainly achieve the purpose of changing the dielectric constant and magnetic permeability of each point of the metamaterial by periodically arranging different man-made metal microstructures on the substrate.
  • it is not the only way to arrange the artificial metal microstructure on the metamaterial substrate, and arrange the artificial metal micro on the metamaterial substrate. The structural process is complicated and difficult to implement.
  • the technical problem to be solved by the present invention is that the non-uniform material of the prior art cannot be arbitrarily designed, and thus the defects of the electromagnetic wave deflection cannot be satisfied under some special circumstances, and an electromagnetic wave capable of freely designing and adapting to various application conditions is provided. Deflection of metamaterials.
  • the technical solution adopted by the present invention to solve the technical problem thereof is to provide a metamaterial for realizing electromagnetic wave deflection, which comprises a functional layer, the functional layer comprising a plurality of mutually parallel slices, each of the slices comprising a slice a plurality of artificial microstructures arranged in an array on the sheet substrate or a plurality of small holes formed in the sheet substrate, the sheet substrate comprising a plurality of unit blocks, each of the The artificial microstructure or the small hole forms a cell with the unit block occupied thereby, and the refractive index of each of the plurality of cells arranged in the first direction of each of the slices gradually changes, each of the The cells have anisotropic electromagnetic parameters.
  • the refractive indices of the plurality of cells arranged in the first direction of each of the sheets gradually become smaller, and each of the layers is in a second direction perpendicular to the first direction a plurality of the cells arranged to have the same or gradually decreasing refractive index, and the plurality of cells arranged in a third direction perpendicular to the surface of the sheet have the same or gradually decreased refractive index small.
  • a plurality of the artificial microstructures on each of the sheets have the same pattern, and a plurality of the artificial microstructures arranged along the first direction are gradually reduced in size, each of which is The plurality of the artificial microstructures arranged in the second direction are the same size or gradually decreasing, and each of the plurality of artificial microstructures arranged along the third direction The dimensions are the same or gradually decreasing.
  • the artificial microstructure has a non-90 degree rotationally symmetrical pattern, and the artificial microstructure is a planar I-shaped structure or a planar snow-like structure.
  • each of the artificial microstructures is a wire constituting a geometric figure, and the number and size of the wires attached to the sheet substrate are gradually decreased along the first direction, so that each of the pieces The refractive indices of the plurality of cells arranged in the first direction of the layer gradually decrease.
  • each of the artificial microstructures is identical, and the number of the artificial microstructures attached to the sheet substrate is not completely the same.
  • the artificial microstructure is a planar "work" shape, including two parallel and equal to each other. And a first wire, the two ends of which are respectively connected to the two first wires and perpendicular to the second wire of the first wire.
  • the artificial microstructure is a "ten" shape, a ring having a notch or a closed curve. Further, the artificial microstructure is a three-dimensional structure comprising three orthogonal wires that are perpendicular to each other and intersect at one point, and end wires that are vertically connected at both ends of each of the orthogonal wires.
  • optical axes of the plurality of cells arranged in the first direction of each of the sheets are rotated in parallel or sequentially.
  • the ratio of the aperture volume to the cell volume in the plurality of cells arranged along the first direction gradually changes, and the medium filled in the aperture is the same, such that each A refractive index of a plurality of the cells arranged in the first direction of the sheet gradually changes.
  • one of the small holes is formed in each of the cells, and the size of the small holes of the plurality of cells arranged in the first direction gradually changes.
  • a plurality of the small holes having the same volume are formed in each of the cells, and refractive indexes of the plurality of cells arranged in the first direction are gradually changed.
  • the refractive index of the medium filled in the small hole is smaller than the refractive index of the sheet substrate, and the small pore volume in the plurality of cells arranged along the first direction and the unit
  • the trend of the ratio of the volume of the lattice is opposite to the tendency of the refractive index of the whole of the metamaterial.
  • the refractive index of the medium filled in the small hole is larger than the refractive index of the sheet substrate, and the small pore volume in the plurality of cells arranged along the first direction and the unit
  • the ratio of the change in the lattice volume is the same as the change in the refractive index of the entire metamaterial.
  • the ratio of the small hole volume in the plurality of cells arranged in the first direction to the cell volume is the same, and the medium filled in the small hole is different, so that each The refractive indices of the plurality of cells arranged in the first direction of the sheet gradually change.
  • the medium filled in the small holes in the plurality of cells arranged in the first direction is a medium whose refractive index gradually changes.
  • the cell size is less than one fifth of the wavelength of the electromagnetic wave of the desired deflection.
  • the metamaterial further includes an impedance matching layer disposed on the incident surface and/or the exit surface of the functional layer; the manufacturing material of the sheet substrate comprises a ceramic material, a polymer material, a ferroelectric material or a ferrite material. .
  • the implementation of the ultra-material for realizing electromagnetic wave deflection of the present invention has the following beneficial effects:
  • the present invention uses a metamaterial technique to realize electromagnetic wave deflection, and the metamaterial is composed of a plurality of sheets, and the artificial microstructure on each layer is changed.
  • the refractive index of the corresponding portion can be changed. Therefore, by uniformly designing the specific shape and structure of each artificial microstructure, an orderly varying refractive index can be obtained, thereby forming an artificial material having a non-uniform refractive index, thereby realizing deflection of electromagnetic waves.
  • the metamaterial of the present invention can meet various electromagnetic wave deflection conditions by arranging different designs of artificial microstructures. Further, by utilizing the characteristics of cell anisotropy, by rotating its optical axis, it is possible to control the position at which electromagnetic waves are emitted.
  • FIG. 1 is a schematic structural view of a functional layer of a metamaterial for realizing electromagnetic wave deflection provided by the present invention
  • FIG. 2 is a schematic cross-sectional view showing an index ellipsoid in an xy plane
  • FIG. 3 is a schematic structural view of a metamaterial functional layer of a first embodiment of the present invention.
  • FIG. 4 is a schematic structural view of a metamaterial functional layer of a second embodiment of the present invention.
  • FIG. 5 is a schematic structural view of a metamaterial for realizing electromagnetic wave deflection provided by the present invention.
  • Figure 6 is a schematic view of a planar snowflake structure in the artificial microstructure of the present invention.
  • FIG. 7 is a schematic view showing a cubic structure unit of a first embodiment of a super-material for realizing electromagnetic wave deflection according to a third embodiment of the present invention.
  • Figure 8 is a schematic view showing the structure of a metamaterial formed by stacking the cubic structural units shown in Figure 7 in the XYZ direction;
  • Figure 9 is a front view of the metamaterial shown in Figure 8;
  • FIG. 10 is a front view of a second embodiment of a metamaterial according to the present invention for realizing electromagnetic wave deflection
  • FIG. 11 is a front view of a fourth embodiment of a metamaterial for realizing electromagnetic wave deflection according to the present invention
  • Figure 12 is a schematic view showing the structure of a fifth embodiment of the super-material for realizing electromagnetic wave deflection of the present invention
  • Figure 13 is a schematic view showing the structure of the embodiment shown in Figure 12 for deflecting the direction of propagation of electromagnetic waves;
  • Figure 14 is a schematic view of an artificial microstructure of a sixth embodiment of the present invention.
  • Figure 15 is a schematic view of an artificial microstructure of a seventh embodiment of the present invention.
  • Figure 16 is a schematic structural view of a super-material sheet according to an eighth embodiment of the present invention.
  • FIG. 17 is a structural view of a metamaterial for realizing electromagnetic wave deflection obtained by superposing super-material sheets shown in FIG. 16;
  • Figure 18 is a schematic view showing the structure of an artificial microstructure according to a ninth embodiment of the present invention.
  • Supermaterial refers to artificial composite structures or composite materials that have extraordinary physical properties not found in natural materials. Through the orderly design of the structure at the key physical scale of the material, it is possible to break through the limitations of certain apparent natural laws, thereby obtaining the extraordinary material function beyond the ordinary nature inherent in nature.
  • Supermaterial is usually a composite material with a novel artificial structure
  • the metamaterial for realizing electromagnetic wave deflection includes a functional layer 10 including a plurality of mutually parallel sheet layers 1, each of which includes a sheet substrate 2 And a plurality of artificial microstructures 3 arranged in an array arranged on the sheet substrate, the sheet substrate 2 being divided into a plurality of unit blocks V, each of the artificial microstructures 3 constituting a cell 4 with the unit block V occupied by the same
  • a functional layer 10 including a plurality of mutually parallel sheet layers 1, each of which includes a sheet substrate 2 And a plurality of artificial microstructures 3 arranged in an array arranged on the sheet substrate, the sheet substrate 2 being divided into a plurality of unit blocks V, each of the artificial microstructures 3 constituting a cell 4 with the unit block V occupied by the same
  • Each layer 1 along the first The plurality of cells 4 arranged in the direction gradually decrease in refractive index, and each of the cells 4 has an anisotropic electromagnetic parameter.
  • Each unit block may be an identical block, which may be a cube or a rectangular parallelepiped.
  • the length, width and height of each unit block V are between one tenth and one fifth of the wavelength of the incident electromagnetic wave.
  • Each cell 4 has an anisotropic electromagnetic parameter.
  • the refractive index distribution of each point in the cell space is not the same for each point, and its refractive index is an ellipsoidal distribution. This ellipsoid is called an index ellipsoid.
  • the index ellipsoid can be calculated by the prior art simulation software and calculation method.
  • the first direction in Fig. 1 refers to the X-axis direction in the figure.
  • isotropic means that for any electromagnetic wave incident at any angle on the two-dimensional plane, the electric field response and the magnetic field response of the artificial microstructure on the plane are the same, That is, the dielectric constant and the magnetic permeability are the same; for an artificial microstructure having a three-dimensional structure, isotropic refers to the electric field response of each of the above-mentioned artificial microstructures in three-dimensional space for electromagnetic waves incident in any direction in three-dimensional space. The magnetic field response is the same.
  • the artificial microstructure is a 90-degree rotationally symmetric structure, the artificial microstructure is characterized by isotropy.
  • 90 degree rotational symmetry means that it aligns with the original structure arbitrarily rotated 90 degrees around a plane perpendicular to the plane and passing its symmetry center on the plane; for a three-dimensional structure, if there are two or two vertical And the three rotation axes of the intersection point (the intersection point is the rotation center), so that the structure rotates 90 degrees around any rotation axis and overlaps with the original structure or is symmetric with the original structure by a boundary, the structure is 90 degree rotation symmetry. structure.
  • the artificial microstructure does not satisfy the plane or three-dimensional 90 degree rotational symmetry (non-90 degree rotational symmetry), it is anisotropic (there is also two-dimensional anisotropy and three-dimensional anisotropy).
  • FIG. 2 is a schematic cross-sectional view of the ellipsoid of the refractive index ellipsoid in the xy plane of the incident direction of the electromagnetic wave (taking an I-shaped artificial microstructure as an example), the cross section being an ellipse, and the ne axis representing the light of the refractive index ellipsoid 5 Axis, set the origin of the two-dimensional plane coordinate 0 at the center of the index ellipsoid, with the ne axis as the y axis, the direction perpendicular to the y axis as the X axis, and the index ellipsoid at any point on the xy plane with nx, Ny said that as common knowledge, we know that the two components of the wave propagation constant k of the light passing through the index ellipsoid in the y-axis and the X-axis direction can be expressed by the following two formulas, that is, k
  • the propagation constant k is also ellipsoidal in three-dimensional space, and its relationship with the index ellipsoid is the same shape and orthogonal.
  • This ellipsoid defining k is a wave propagation ellipsoid 6. It can be seen that the wave propagation ellipsoid 6 has the same shape as the index ellipsoid 5 (the dimensions are not necessarily the same), and the long axis direction of the wave propagation ellipsoid 6 is the short axis direction of the index ellipsoid, and the wave propagation ellipsoid 6 is short.
  • the axial direction is the long axis direction of the refractive index ellipsoid.
  • the x and y axes in Fig. 2 are only definitions for deriving the wave propagation ellipsoid 6, which is different from the other figures.
  • the deflection direction of the electromagnetic wave after passing through the cell 4 can be drawn by the wave propagation ellipsoid.
  • the electromagnetic wave incident in the direction shown in FIG. 2 intersects with the point on the surface of the wave propagation ellipsoid 6 to be emitted, and the intersection point of the wave propagation ellipsoid 6 is made at this intersection point, from the intersection point
  • the normal direction of the tangent is the direction of propagation of the energy s of the electromagnetic wave, so that the electromagnetic wave propagates in this direction in the metamaterial.
  • the normal line extends to intersect with a surface of the electromagnetic wave splitting element, that is, the exit surface, and the intersection from the exit surface continues to exit in a direction parallel to the incident direction, and the outgoing direction It is the direction of electromagnetic wave phase propagation. That is to say, the anisotropic metamaterial can change the direction of energy propagation of the electromagnetic wave passing through it without changing its phase propagation direction, and the electromagnetic wave is shifted when it exits.
  • the refractive index distribution in the metamaterial is uniform, and the uniformity here means that each cell has the same refractive index ellipsoid.
  • the direction of energy propagation and the direction of phase propagation of electromagnetic waves change after passing through such metamaterials.
  • the phase propagation direction is determined by the non-uniform distribution of the refractive index
  • the energy propagation direction is determined by the distribution of the anisotropic cell optical axis.
  • Each of the sheets 1 of the present invention has two surfaces which are front and rear parallel, and thus each layer is a sheet having a uniform thickness.
  • the first direction referred to in the present invention refers to the direction of the columns of the artificial microstructures 3 arranged in an array on each of the layers 1, the second direction refers to the direction of the rows of the array, and the third direction below refers to the vertical direction.
  • the direction of the surface of the sheet In the drawings (except Figure 2), the first direction, the second direction, and the The three directions are represented by the X-axis, y-axis, and z-axis directions of the three-dimensional coordinate system, respectively.
  • ⁇ the magnetic permeability
  • ⁇ the dielectric constant
  • FIG. 3 is a schematic structural view of a metamaterial functional layer 10 according to a first embodiment of the present invention, the artificial microstructure 3 being an I-shaped metal microstructure, and an artificial microstructure 3 on each layer 1 of the functional layer 10.
  • a plurality of artificial microstructures 3 on each layer 1 Arranged in a rectangular array, a plurality of artificial microstructures 3 on each layer 1 have the same I-shaped pattern, and a plurality of artificial microstructures 3 arranged along the y-axis direction are gradually reduced in size, and are along the X-axis direction.
  • the plurality of artificial microstructures 3 arranged in the same size remain unchanged. It has been experimentally found that the dielectric constant of the metal microstructure of the same pattern exhibited in the same cell is proportional to its size.
  • the regular arrangement of the size of the artificial microstructure is actually the regular arrangement of the dielectric constant of the cell 4, and in the case where the magnetic permeability is constant, it can be regarded as the cell 4.
  • the regular distribution of the refractive index Therefore, in the present embodiment, the refractive indices of the plurality of cells 4 on each column gradually decrease in the y direction, and the refractive indices of the plurality of cells 4 in the X direction remain unchanged.
  • the size of the artificial microstructures 3 of the plurality of cells 4 arranged in the z-axis direction is also kept constant, and therefore, the refractive indices of the plurality of cells 4 arranged along the z-axis direction are also not maintained. change.
  • the optical axis directions of all the cells 4 are parallel, and have an angle of not zero with respect to the X-axis direction.
  • the direction of the optical axis is the short-axis direction of the wave propagation ellipsoid. Therefore, it can be said that the short-axis direction of the wave-propagating ellipsoid has a non-zero angle with the X-axis direction.
  • each cell has a deflection effect on the electromagnetic wave (so that the electromagnetic wave is always deflected in the same direction), and after the electromagnetic wave passes through the plurality of cells, The deflection effect is accumulated, and due to the anisotropy of each cell, the exit position of the electromagnetic wave can be controlled, that is, by controlling the angle between the optical axis and the X-axis, the electromagnetic emission position can be controlled.
  • 4 is a schematic structural view of a metamaterial functional layer according to a second embodiment of the present invention. Different from the first embodiment, in this embodiment, the optical axis directions of the cells 4 on each of the layers 1 are not parallel, in order.
  • the rotation form is the angle at which the refractive index of the sheet layer 1 is the largest, and the angle between the optical axis direction (the short-axis direction of the wave propagation ellipsoid in the figure) and the X-axis direction is 0 degree.
  • the position where the refractive index of the sheet layer 1 is the smallest, the angle between the optical axis direction and the X-axis direction is 90 degrees.
  • each cell has a deflection effect on the electromagnetic waves (so that the electromagnetic waves are always deflected in the same direction), and after the electromagnetic waves pass through the plurality of cells, The deflection effect is accumulated, and due to the anisotropy of each cell, the exit position of the electromagnetic wave can be controlled.
  • the electromagnetic wave can be more gathered to achieve a more concentrated energy. That is, the anisotropic deflection technique is used to deflect the electromagnetic wave, and the deflection is achieved by using the non-uniform (isotropic non-uniformity) of the refraction, which has an additional effect, for example, the electromagnetic wave is more divergent and more concentrated. Or, when the electromagnetic wave is deflected, the electromagnetic wave is split.
  • the sheet substrate 2 of the functional layer 10 of the present invention may be made of a ceramic material, a polymer material, a ferroelectric material, a ferrite material or a ferromagnetic material.
  • the above polymer material may be polytetrafluoroethylene.
  • PTFE has excellent electrical insulation, so it does not interfere with the electric field of electromagnetic waves, and has excellent chemical stability, corrosion resistance, long service life, and is a good choice for substrates attached to metal microstructures.
  • the above polymer material may be a composite material such as FR-4 or F4b.
  • the artificial microstructure of the present invention preferably employs a metal microstructure which is a metal wire having a predetermined pattern.
  • a metal wire such as a copper wire or a silver wire.
  • the above metal wires may be attached to the sheet substrate by etching, plating, drilling, photolithography, electron engraving or ion etching. Of course, a three-dimensional laser processing process can also be employed.
  • FIGS. 1 to 4 adopt an I-shaped artificial microstructure, and the I-shape is a relatively simple structure of anisotropy.
  • the artificial microstructure of the present invention may also be as shown in FIG. Flat snowflake structure.
  • it is an I-shaped artificial microstructure or an artificial micro-structure of a flat snow fever as shown in Fig. 6, as long as it has an anisotropic (non-rotating 90-degree symmetrical pattern) characteristic.
  • the metamaterial may further include an impedance matching layer provided on the incident surface and/or the outgoing surface of the functional layer 10.
  • an impedance matching layer (201, 202) is provided on both the entrance surface and the exit surface.
  • the present invention achieves impedance matching by the impedance of the side of the impedance matching layer 201 on the incident side that is in contact with the incident side medium (for example, air) is close to the impedance of the incident medium, and the incident side impedance matching layer 201
  • the impedance of one side of the functional layer 10 is close to the incident side impedance of the functional layer 10, and the impedance of the incident side impedance matching layer 201 continuously changes its impedance in a direction perpendicular to the functional layer.
  • the impedance of the side of the impedance matching layer 202 on the exit side that is in contact with the exit side medium (for example, air) is close to the exit medium, and the side of the exit side impedance matching layer 202 near the functional layer 10 has its impedance and functional layer.
  • the exit side impedance of 10 is close, and the impedance of the exit side impedance matching layer continuously changes in impedance perpendicular to the functional layer.
  • the larger the impedance difference between different media interfaces the stronger the reflection. Therefore, through the above impedance matching layer (201, 202), the impedance mutation can be eliminated, thereby eliminating the reflection phenomenon when electromagnetic waves pass through different media interfaces. Electromagnetic wave energy loss problem.
  • the impedance matching layer described above may also be a metamaterial having a similar structure to the functional layer. Of course, it can also be other materials with similar functions.
  • the impedance referred to herein refers to the wave impedance.
  • impedance Z ⁇
  • the internal impedance distribution of the impedance matching layer can be realized by the distribution of the dielectric constant, that is, the impedance distribution inside the impedance matching layer can be artificially designed.
  • the supermaterial as a whole can be seen as a plurality of cubic structural units superposed in a three-dimensional XYZ direction. Since the metamaterial itself has an influence on electromagnetic waves, it is required that the size of the solid structural unit is smaller than one fifth of the wavelength of the electromagnetic wave of the desired response. Preferably, each cubic structural unit is of equal size and is required One tenth of the wavelength of the electromagnetic wave that responds.
  • the response of the metamaterial to the electromagnetic field is mainly determined by the response of each cubic structural unit to the electromagnetic field.
  • the response of each cubic structural unit to the electromagnetic field will be superimposed to macroscopically change the physical properties of the incident electromagnetic wave.
  • the metamaterial that realizes the deflection of the electromagnetic wave needs to be in at least one direction.
  • the refractive index of the X direction is gradually changed, and the refractive index of the Y direction and the Z direction is constant or gradually changes.
  • the rate of change of the refractive index in this direction is large. The gradual decrease in this paper refers to the data of the next reference point is less than or equal to the data of the previous reference point.
  • the rate of change is large, which means that among the three reference points arranged one after another, the difference between the second reference point and the third reference point is greater than the difference between the first reference point and the second reference point.
  • the magnetic permeability at the electromagnetic wave frequency can change the dielectric constant and magnetic permeability of each point to finally achieve the purpose of deflecting electromagnetic waves of the present invention.
  • FIG. 7 is a schematic diagram of a cubic structural unit of a third embodiment of a metamaterial for realizing electromagnetic wave deflection according to the present invention
  • FIG. 8 is a third embodiment of the present invention.
  • - a schematic view of a metamaterial structure in which the directions are stacked
  • Fig. 9 is a front view showing a third embodiment of the present invention.
  • the cubic structural unit in FIG. 9 includes a substrate 11 and an aperture 20 formed in the substrate 11.
  • the aperture 20 may or may not be a through hole but both occupy a certain volume of the substrate 11.
  • the volume of the small holes 20 formed in the base material of the metamaterial cubic structure unit occupies the volume ratio of the substrate 11 in the ⁇ direction, and remains unchanged along the X and ⁇ directions, thereby causing the refractive index to gradually decrease along the ⁇ direction.
  • the apertures 20 may be filled with a medium to change the dielectric constant and magnetic permeability of the cubic structural unit. Since the present embodiment mainly changes the dielectric constant and the magnetic permeability by changing the size of the small hole 20 in the cubic structural unit, the medium filled in each small hole 20 in this embodiment is the same but different from the substrate material. It can be air, ceramic, polymer material, ferroelectric material or ferrite material. The medium filled in this embodiment is air. Since the refractive index of the air is definitely smaller than the refractive index of the substrate, the change in the volume ratio of the cubic structural unit of the small pores 20 is still gradually increased in the ⁇ direction so that the overall refractive index of the supermaterial gradually decreases in the Y direction.
  • the refractive index of the medium filled in the small hole 20 is larger than the refractive index of the substrate, the larger the volume of the small hole 20 is, the larger the refractive index of the cubic structural unit is. Therefore, the volume ratio of the cubic structural unit occupied by the small hole 20 at this time tends to change. In order to gradually decrease in the Y direction, the overall refractive index of the metamaterial gradually increases in the ⁇ direction.
  • Changing the apertures 20 has a different embodiment of the volume of the cubic structural unit.
  • the first embodiment is shown in Fig. 7, Fig. 8, and Fig. 9.
  • Fig. 10 is a front elevational view showing a second embodiment in which the small holes 20 are changed to occupy the volume of the cubic structural unit.
  • a plurality of small holes 20 are formed in the cubic structural unit substrate, and the number of small holes 20 in the plurality of cubic structural unit substrates arranged in the Y direction is gradually increased to increase the volume ratio of the cubic structural units of the small holes 20. .
  • the small holes 20 can still be filled with a medium different from the material of the substrate. In the present embodiment, the filling medium is air.
  • the refractive index of the air is definitely smaller than the refractive index of the substrate, the variation of the number of small holes 20 of the cubic structural unit is still gradually increased in the Y direction so that the overall refractive index of the supermaterial gradually decreases in the Y direction.
  • the refractive index of the medium filled in the small hole 20 is larger than the refractive index of the substrate, the larger the number of the small holes 20, the larger the refractive index of the cubic structural unit is. Therefore, the number of small holes 20 of the cubic structural unit changes toward the edge.
  • the Y direction is gradually reduced so that the overall refractive index of the metamaterial gradually increases in the Y direction.
  • the cross-sectional shapes of the various types of small holes 20 are not necessarily the circular shapes shown in FIG. 9 and FIG. 10, and may be various shapes such as square, triangular, trapezoidal, etc., as long as the design thinking of the embodiment is satisfied. It is thought that the volume ratio of the cubic structural unit occupied by the small hole 20 in one direction can be gradually changed. Similarly, if you want to achieve the effect of deflecting electromagnetic waves in both the X direction and the Z direction, you only need to apply the distribution trend of the small holes 20 in the cubic structural unit along the Y direction.
  • Figure 11 is a front elevational view of a fourth embodiment of a metamaterial for achieving electromagnetic wave deflection in accordance with the present invention.
  • the volume of the small holes 20 in the cubic structural unit substrate accounts for the same ratio of the volume of the cubic structural unit.
  • the small holes 20 may be the same number, the same size, the same cross-sectional pattern, or different numbers, different cross-sectional patterns or different sizes, but only need to satisfy all the small holes 20 in all the cubic structural unit substrates.
  • the ratio of the volume of the cubic structural unit is the same.
  • the number of the small holes 20 in the cubic structural unit substrate is the same, one is the same, the same size, the same cross-sectional pattern, and all are circular, as a preferred embodiment.
  • the Y direction is still the first direction, and only the embodiment in which the refractive index gradually decreases in the Y direction is described.
  • the embodiment in which the refractive index gradually decreases along the X, along the Z, or in the mixing direction of the three can be followed by Embodiments in which the refractive index in the Y direction is gradually reduced are easily introduced.
  • each of the small holes 20 occupies the same volume ratio of the cubic structural unit, so the small holes 20 of the plurality of cubic structural units arranged in the Y direction are filled with different media to change the dielectric constant of the cubic structural unit and Magnetic permeability.
  • a medium having a gradually reduced magnetic permeability For example, iodine crystals, copper oxide, crystal, quartz, polystyrene, sodium chloride, glass, and air are sequentially packed.
  • the shading in the small hole 20 in Fig. 11 indicates the filled medium, and the higher the density of the shadow indicates the greater the refractive index of the filling medium.
  • the various embodiments of the third embodiment described above and the various embodiments of the fourth embodiment can be combined to facilitate a combination of various possible embodiments.
  • the volume of the small holes 20 is different in the volume of the cubic structural unit, and the small holes 20 are also filled with a medium having a different refractive index.
  • the invention relates to a metamaterial for realizing electromagnetic wave deflection which can deflect the electromagnetic wave propagation direction.
  • a metamaterial for realizing electromagnetic wave deflection which can deflect the electromagnetic wave propagation direction.
  • FIG. 12 it is composed of at least one metamaterial sheet.
  • it is vertical. Stacked in the direction of the surface of the sheet and formed into a three-dimensional whole by a certain assembly or connection.
  • each of the sheets includes a sheet-like substrate 2 and a plurality of artificial microstructures 3 attached to the substrate 2.
  • the sheet-like substrate 2 has front and rear two mutually parallel surfaces such that the substrate 2 is an equal-thick sheet.
  • the direction in which the metamaterial sheets 1 are stacked is the third direction ⁇ .
  • the artificial microstructure 3 is attached to the substrate 2, including two cases: one is that the artificial microstructure 3 is a planar structure attached to the front surface of the substrate 2; the other is that the artificial microstructure 3 is a three-dimensional structure. It adheres to the inside of the sheet substrate 2.
  • Each of the artificial microstructures 3 is usually composed of a metal wire such as silver or copper, or may be composed of a non-metallic wire. These wire bonds are inscribed on the surface of the substrate 2 or inside the substrate 2 and form a certain geometry.
  • the substrate 2 is divided into a plurality of equal cubic substrate units, for example, cubes whose length, width, and height are one tenth of the wavelength of the incident electromagnetic wave, and a certain number of artificial microstructures are attached to each of the substrate units. Forming a metamaterial unit 40. Thus each metamaterial unit 40 contains a certain amount of filaments that constitute the artificial microstructure 3.
  • the refractive index of the electromagnetic wave deflecting the electromagnetic wave of the present invention is gradually reduced in at least one direction such as the X direction. Small, and the refractive index of either the ⁇ direction and the ⁇ direction does not change or gradually decreases. In order to make the angle of the deflection large, the rate of change of the refractive index in this direction is large.
  • the gradual decrease in this paper refers to the data of the next reference point is less than or equal to the data of the previous reference point.
  • the rate of change is large, which means that among the three reference points arranged one after another, the difference between the second reference point and the third reference point is greater than the difference between the first reference point and the second reference point.
  • the rule is that the density of the wire on the substrate 2 is large, that is, the position of the wire in the substrate unit is high, and the equivalent refractive index of the substrate unit is large, so that the component is oriented in the X direction. As the refractive index gradually decreases, the content of the filaments in the substrate unit should be gradually reduced at least in the X direction.
  • the substrate unit here may be a conventional volume unit such as cubic millimeters, cubic centimeters, etc., or may be any
  • a custom volume size, such as each of the metamaterial units 40 described above, is a substrate unit, and the entire metamaterial sheet 1 is comprised of tens of thousands of metamaterial units 40.
  • each metamaterial unit 40 contains an artificial microstructure 3
  • the filament content of the base unit is gradually decreased, and the refractive index is gradually decreased, such as As shown in Fig. 12 and Fig. 13, at this time, each of the metamaterial units 40 has the same size in the Y direction, and the refractive index in the Y direction does not change.
  • the metamaterial that realizes the electromagnetic wave deflection of the present invention can gradually reduce the refractive index in the Y direction according to the same principle as the X direction, and the Z direction is also the same.
  • the super material which realizes the electromagnetic wave deflection can be designed to make the super material units along the X direction.
  • the number of artificial microstructures 3 of 40 is gradually reduced to achieve a gradual decrease in the wire content and a gradual decrease in the refractive index.
  • the Y direction and the Z direction are also the same.
  • the artificial microstructure 3 of the present invention may be of any shape.
  • the artificial microstructure 3 may be a "work" shape as shown in FIG. 12 and FIG. 13, including two first wires 50 that are parallel and equal to each other, and two ends are respectively connected to the two first wires. a second wire 51 having a midpoint and perpendicular to the first wire 50;
  • the artificial microstructure 3 may also be a "ten" shape, as shown in Fig. 14, comprising two long wires 60 intersecting perpendicularly and respectively A short wire 61 attached to and perpendicular to each of the long wires 60;
  • the artificial microstructure 3 may also be a ring having a notch, as shown in FIG.
  • the super-material for realizing electromagnetic wave deflection of the present embodiment includes a plurality of the same super-material sheet layers 1, that is, the refractive index in the Z direction is unchanged. .
  • the refractive index in the X direction gradually decreases, and the refractive index in the Y direction does not change.
  • the array of the artificial microstructures 3 arranged inside the substrate 2 is gradually reduced in size in the X direction, Y. The direction size does not change.
  • the artificial microstructure 3 of the present embodiment includes two orthogonal wires 70 perpendicular to each other and intersecting at one point, and are respectively vertically connected at both ends of each of the orthogonal wires 70 and are orthogonally golded.
  • the wire 70 is divided into end wires 71.
  • the three-dimensional artificial microstructure 3 can also be implemented in various ways, such as the regular tetrahedral frame formed by the four wires connected as shown in FIG. 18, and any other three-dimensional structure such as an arbitrary space curve. Five prismatic frames, rings, and more.
  • the metamaterial for realizing the electromagnetic wave deflection of the present invention is not limited to all the artificial microstructures 3 having the same shape, and each of the artificial microstructures 3 may have any different shape, for example, the component may At the same time, it includes an artificial microstructure 3 with a "work" shape and a circular shape;
  • the artificial microstructure 3 is not necessarily scaled down as in the above embodiment, and the filament content of the metamaterial unit 40 can be gradually reduced by gradually reducing one or several wires of the artificial microstructure to thereby gradually reduce the refractive index.
  • the length of the second wire 51 of each column of artificial microstructures is gradually decreased in the X direction
  • the length of the first wire 50 is constant, along the Y direction
  • the individual artificial microstructures in the Z direction are the same. This design also achieves the purpose of gradually decreasing the refractive index in the X direction and the refractive index in the Y direction and the Z direction.
  • the metamaterial for realizing electromagnetic wave deflection of the present invention is realized by a metamaterial technology, and the metamaterial is composed of a plurality of metamaterial sheets, and the refractive index of the corresponding portion can be changed by changing the artificial microstructure on each of the supermaterial sheets. Therefore, by uniformly designing the specific shape and structure of each artificial microstructure, an orderly varying refractive index can be obtained, thereby forming a non-uniform material, thereby realizing deflection of electromagnetic waves. It can be seen that the metamaterial for realizing electromagnetic wave deflection of the present invention can be freely designed and combined, and can meet various electromagnetic wave deflection conditions.

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Description

一种实现电磁波偏折的超材料
【技术领域】
本发明涉及电磁通信领域，更具体地，涉及一种实现电磁波偏折的超材料。 【背景技术】
通讯领域主要依赖电磁波来进行探测、 定位、 通信等。 电磁波可以通过不 同的材料或元器件实现分离、 汇聚、 偏折、 发散等。 能实现电磁波偏折即使电 磁波传播方向改变的材料主要是非均匀材料， 也就是不均质从而导致折射率的 分布不均衡的材料。材料疏密不同、材质不同等都会使得折射率的分布有变化。
现有技术的用于使电磁波偏折的非均匀材料通常是通过折射率不同的多层 材质叠加所形成的整体。 根据将要被偏折的电磁波的频率、 波长等特性， 可以 设计出此非均匀材料的折射率分布， 然后在各分布区域选择具有对应折射率的 合适材料。
这种偏折电磁波的材料的缺陷在于， 现有的材料其折射率是固有的， 并不是 可任意设计的， 当所需的折射率分布中部分区域的折射率用现有的天然材料无 法得到， 将导致整个非均匀材料不能达到所需的偏折要求。
超材料是指一些具有天然材料所不具备的超常物理性质的人工复合结构或 复合材料。 通过在材料的关键物理尺度上的结构有序设计， 可突破某些表观自 然规律的限制， 从而获得超出自然界固有的普通的超常材料功能。
目前常规的超材料主要是通过在基材上周期排列不同的人造金属微结构从 而达到改变超材料各点的介电常数和磁导率的目的。 然而想要改变超材料各点 的介电常数和磁导率以实现不同的功能， 在超材料基材上排列人造金属微结构 并不是唯一的办法， 且在超材料基材上排列人造金属微结构工艺复杂、 实现困 难。
【发明内容】 本发明要解决的技术问题在于， 针对现有技术的非均匀材料不能任意设计因 而在有些特殊情况下无法满足电磁波偏折要求的缺陷， 提供一种可以自由设计 也适应各种应用条件的实现电磁波偏折的超材料。
本发明解决其技术问题所采用的技术方案是提出一种实现电磁波偏折的超 材料， 其包括一功能层， 所述功能层包括多个相互平行的片层， 每一所述片层 包括片状基板和附着在所述片状基板上阵列排布的多个人造微结构或在所述片 状基板中形成的多个小孔， 所述片状基板包括多个单元块， 每一所述人造微结 构或所述小孔与其所占据的所述单元块构成一个单元格， 每一所述片层沿第一 方向排布的多个所述单元格的折射率逐渐变化， 每一所述单元格具有各向异性 的电磁参数。
进一歩地， 每一所述片层沿所述第一方向排布的多个所述单元格的折射率逐 渐变小， 每一所述片层沿垂直于所述第一方向的第二方向排布的多个所述单元 格的折射率相同或逐渐减小， 所述超材料沿垂直于所述片层表面的第三方向排 布的多个所述单元格的折射率相同或逐渐减小。
进一歩地， 每一所述片层上的多个所述人造微结构具有相同的图案， 并且沿 所述第一方向排布的多个所述人造微结构的尺寸逐渐减小， 每一所述片层沿所 述第二方向排布的多个所述人造微结构的尺寸相同或逐渐减小， 每一所述片层 沿所述第三方向排布的多个所述人造微结构的尺寸相同或逐渐减小。
进一歩地， 所述人造微结构具有非 90度旋转对称的图形， 所述人造微结构 为平面的 I形结构或平面雪花状结构。
进一歩地， 每一所述人造微结构为构成几何图形的丝线， 附着在所述片状基 板上的所述丝线数量和尺寸沿所述第一方向逐渐减小， 以使每一所述片层沿所 述第一方向排布的多个所述单元格的折射率逐渐减小。
进一歩地， 每个所述人造微结构完全相同， 附着在所述片状基板上的所述人 造微结构的数量不完全相同。
进一歩地， 所述人造微结构为平面的 "工"字形， 包括相互平行且相等的两 个第一金属丝、 两端分别连接在所述两第一金属丝上且垂直于所述第一金属丝 的第二金属丝。
进一歩地， 所述人造微结构为 "十"字形、 具有缺口的圆环或封闭曲线。 进一歩地， 所述人造微结构为三维结构， 包括两两垂直且相交于一点的三根 正交金属丝和分别垂直连接在每根所述正交金属丝两端的端部金属丝。
进一歩地， 每一所述片层沿所述第一方向排布的多个所述单元格的光轴平行 或依次旋转。
进一歩地， 沿所述第一方向排布的多个所述单元格中的所述小孔体积与所述 单元格体积的比值逐渐变化， 且所述小孔内填充的介质相同， 使得每一所述片 层沿所述第一方向排布的多个所述单元格的折射率逐渐变化。
进一歩地， 每一所述单元格中形成一所述小孔， 沿所述第一方向排布的多个 所述单元格的所述小孔的尺寸逐渐变化。
进一歩地， 每一所述单元格中形成多个体积相同的所述小孔， 沿所述第一方 向排布的多个所述单元格的折射率逐渐变化。
进一歩地， 所述小孔内填充所述介质的折射率小于所述片状基板的折射率， 沿所述第一方向排布的多个所述单元格中的小孔体积与所述单元格体积的比值 变化趋势与所述超材料整体的折射率变化趋势相反。
进一歩地， 所述小孔内填充所述介质的折射率大于所述片状基板的折射率， 沿所述第一方向排布的多个所述单元格中的小孔体积与所述单元格体积的比值 变化趋势与所述超材料整体的折射率变化趋势相同。
进一歩地， 沿所述第一方向排布的多个所述单元格中的所述小孔体积与所述 单元格体积的比值相同， 且所述小孔内填充的介质不同， 使得每一所述片层沿 第一方向排布的多个所述单元格的折射率逐渐变化。
进一歩地， 沿所述第一方向排布的多个所述单元格中的所述小孔填充的所述 介质为折射率逐渐变化的介质。
进一歩地， 所述单元格尺寸小于所需偏折的电磁波波长的五分之一。 进一歩地，所述超材料还包括设置在功能层入射面和 /或出射面上的阻抗匹配 层； 所述片状基板的制造材料包括陶瓷材料、 高分子材料、 铁电材料或铁氧材 料。
实施本发明的实现电磁波偏折的超材料， 具有以下有益效果： 本发明使用超 材料技术来实现电磁波偏折， 超材料是由多个片层构成的， 改变每个片层上的 人造微结构即可改变相应部位的折射率， 因此通过统一设计各个人造微结构的 具体形状和结构即可得到有序变化的折射率， 从而形成折射率非均匀的人造材 料， 进而实现电磁波的偏折。 可见， 本发明的超材料通过对人造微结构的不同 设计排布， 可以满足各种电磁波偏折条件的要求。 并且利用单元格各向异性的 特点， 通过旋转其光轴， 可以对电磁波出射时的位置进行控制。
【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是本发明提供的实现电磁波偏折的超材料其功能层的结构示意图； 图 2是所示为折射率椭球在 xy平面的截面示意图；
图 3是本发明的第一实施例其超材料功能层的结构示意图；
图 4是本发明的第二实施例其超材料功能层的结构示意图；
图 5是本发明所提供的实现电磁波偏折的超材料其结构示意图；
图 6是本发明的人造微结构中的平面雪花状结构的示意图；
图 7为本发明实现电磁波偏折的超材料第三实施例第一实施方式立方体结构 单元示意图；
图 8为由图 7所示立方体结构单元沿 X-Y-Z方向堆叠而成的超材料结构示意 图； 图 9为图 8所示超材料主视图；
图 10为本发明实现电磁波偏折的超材料第三实施例第二实施方式主视图; 图 11为本发明实现电磁波偏折的超材料第四实施例主视图；
图 12是本发明的实现电磁波偏折的超材料的第五实施例的结构示意图； 图 13是图 12所示实施例使电磁波传播方向偏折的结构示意图；
图 14是本发明的第六实施例的人造微结构的示意图；
图 15是本发明的第七实施例的人造微结构的示意图；
图 16是本发明第八实施例的超材料片层的结构示意图；
图 17是图 16所示超材料片层叠加得到的实现电磁波偏折的超材料的结构 意图；
图 18是本发明第九实施例的人造微结构的结构示意图。
【具体实施方式】
结合图 1至图 6对第一实施例和第二实施例进行详细描述。
"超材料"是指一些具有天然材料所不具备的超常物理性质的人工复合结构或 复合材料。 通过在材料的关键物理尺度上的结构有序设计， 可以突破某些表观 自然规律的限制， 从而获得超出自然界固有的普通性质的超常材料功能。
"超材料"所具有的三个重要特征：
( 1 ) "超材料"通常是具有新奇人工结构的复合材料；
(2) "超材料"具有超常的物理性质 （往往是自然界的材料中所不具备的）；
(3 ) "超材料"性质由构成材料的本征性质及其中的人造微结构共同决定。 本发明利用超材料来构建一种实现电磁波偏折的超材料。 具体如下： 如图 1所示， 根据本发明的实现电磁波偏折的超材料包括一功能层 10， 所述 功能层 10包括多个相互平行的片层 1， 每一片层 1包括片状基板 2和附着在片 状基板上阵列排布的多个人造微结构 3， 所述片状基板 2分成多个单元块 V， 每 一人造微结构 3与其所占据的单元块 V构成一个单元格 4， 每一片层 1沿第一 方向排布的多个单元格 4其折射率逐渐减小， 所述每一单元格 4具有各向异性 的电磁参数。 每一单元块可以是完全相同的方块， 可以是立方体， 也可是长方 体， 每一单元块 V的长、 宽、 高尺寸为入射电磁波波长的十分之一至五分之一 之间。 每一单元格 4 具有各向异性的电磁参数是指， 单元格空间中每一点的折 射率分布并不是每点都相同， 其折射率呈椭球分布， 此椭球称为折射率椭球。 对于任一给定的单元格， 可通过现有技术的模拟仿真软件和计算方法算出其折 射率椭球， 图 1中的第一方向是指图中的 X轴方向。
对于具有平面结构的人造微结构， 各向同性， 是指对于在该二维平面上以任 一角度入射的任一电磁波， 上述人造微结构在该平面上的电场响应和磁场响应 均相同， 也即介电常数和磁导率相同； 对于具有三维结构的人造微结构， 各向 同性是指对于在三维空间的任一方向上入射的电磁波， 每个上述人造微结构在 三维空间上的电场响应和磁场响应均相同。 当人造微结构为 90度旋转对称结构 时， 人造微结构即具有各向同性的特征。
对于二维平面结构， 90度旋转对称是指其在该平面上绕一垂直于该平面且过 其对称中心的旋转轴任意旋转 90度后与原结构重合； 对于三维结构， 如果具有 两两垂直且共交点 （交点为旋转中心） 的 3 条旋转轴， 使得该结构绕任一旋转 轴旋转 90度后均与原结构重合或者与原结构以一分界面对称， 则该结构为 90 度旋转对称结构。
相应地， 如果人造微结构不满足平面或三维的 90度旋转对称 （非 90度旋转 对称）， 则其是各向异性 （同样有二维的各向异性与三维的各向异性）。
如图 2所示为折射率椭球的在电磁波的入射方向的 xy平面的截面示意图（以 I形人造微结构为例）， 此截面为一个椭圆， ne轴表示此折射率椭球 5的光轴， 设定二维平面坐标原点 0在折射率椭球的中心上， 以 ne轴为 y轴， 与 y轴垂直 的方向为 X轴， 折射率椭球在 xy平面上的任意一点用 nx， ny表示， 做为公知 常识我们知道， 通过此折射率椭球的光的波其传播常数 k在 y轴与 X轴方向的 两个分量可以由以下两个公式表示， 即 ky=nxaVc， kx=nyro/c; 其中， ω为电磁波 的角频率， C为光速； 通过坐标变换， 我们可以得到传播常数 k在此单元格中也 是呈椭圆分布的， 并且其椭圆与折射率椭球在此 xy平面的椭圆为相同的形状， 且位置上正交。 同理， 我们可以得到传播常数 k在三维空间中也是呈椭球分布 的， 其与折射率椭球的关系为， 形状相同且正交。 定义 k 的这个椭球为波传播 椭球 6。 可见， 波传播椭球 6与折射率椭球 5形状相同 （尺寸不一定相同）， 且 波传播椭球 6的长轴方向为折射率椭球的短轴方向， 而波传播椭球 6的短轴方 向为折射率椭球的长轴方向。 图 2中的 x、 y轴仅是为了推导出波传播椭球 6所 做的定义， 与其它附图不同。
电磁波经过单元格 4后的偏折方向可通过波传播椭球画出来。 如图 2所示， 对于如图 2中所示方向入射的电磁波， 与要出射的波传播椭球 6的面上一点相 交， 做此相交点关于波传播椭球 6 的切线， 自相交点做的切线的法线方向即为 电磁波的能量 s传播方向， 因此电磁波在超材料内部能量 s沿此方向传播。 电磁 波沿此方向前进直至离开超材料时， 所述法线延伸至与电磁波分裂元件的一表 面也即出射面相交后， 自出射面上的交点继续沿与入射方向平行的方向出射， 此出射方向为电磁波相位传播方向。 也就是说， 各向异性超材料， 能改变通过 其中的电磁波的能量传播方向， 而不改变其相位传播方向， 电磁波出射时发生 平移。 当然， 这里有一个前提， 就是超材料中的折射率分布均匀， 此处的均匀 是指， 每一单元格具有相同的折射率椭球。
对于折射率分布不均匀、 且对电磁波呈各向异性的超材料， 电磁波穿过这样 的超材料后其能量传播方向和相位传播方向都会改变。 其中， 相位传播方向由 折射率的非均匀分布决定， 而能量传播方向由各向异性的单元格光轴的分布决 定。
本发明的所述每一片层 1具有前、 后平行的两个表面， 因而每片层均为一厚 度均匀的片层。 本发明中所涉及的第一方向指的是每一片层 1 上阵列排布的人 造微结构 3 的列的方向， 第二方向是指上述阵列的行的方向， 以下的第三方向 是指垂直于片层表面的方向。 各附图中 （图 2除外）， 第一方向、 第二方向及第 三方向分别用三维坐标系的 X轴、 y轴及 z轴方向表示。
折射率可以表示电磁波传播方向的改变， 已知折射率 n= ^， 其中 μ为磁导 率， ε为介电常数。实验证明，电磁波通过超材料时，会向折射率大的方向偏折。 由此， 在磁导率 μ不改变的条件下， 通过改变 ε可以得到我们想要的折射率， 因此通过合理设计功能层 10中内部每一单元格的介电常数， 可以得到任意我们 想要的偏折效果。
图 3所示为本发明第一实施的超材料功能层 10的结构示意图， 所述人造微 结构 3为 I形的金属微结构， 所述功能层 10的每一片层 1上的人造微结构 3呈 矩形阵列排布， 每一片层 1上的多个人造微结构 3具有相同的 I形图案， 并且沿 y轴方向排布的多个人造微结构 3其尺寸逐渐减小，而沿 X轴方向排布的多个人 造微结构 3 其尺寸保持不变。 通过实验得到， 同一图案的金属微结构在同一单 元格中所表现出来的介电常数与其尺寸成正比。 困此， 本实施例中， 人造微结 构尺寸的规律排布实际上是单元格 4 的介电常数的规律排布， 并且在磁导率不 变的情况下， 即可视为是单元格 4折射率的规律分布。 因此， 本实施例中， 每 一列上的多个单元格 4的折射率沿 y方向逐渐减小，而沿 X方向的多个单元格 4 其折射率保持不变。
另外， 本实施中， 沿 z轴方向排布的多个单元格 4其人造微结构 3的尺寸也 保持不变， 因此， 沿 z轴方向排布的多个单元格 4的折射率也保持不变。
同时， 本实施例中， 所有单元格 4的光轴方向平行， 且与 X轴方向具有一不 为零的夹角。 光轴的方向即波传播椭球的短轴方向， 因此， 也可以这么说， 即 波传播椭球的短轴方向与 X轴方向具有一不为零的夹角。
本实施例中， 由于每一列的单元格的折射率规律相同， 因此， 每一单元格都 对电磁波有偏折作用 （使得电磁波始终向同一个方向偏折）， 电磁波通过多个单 元格后， 偏折效果得到累加， 并且由于每个单元格各向异性的特性， 使得电磁 波的出射位置可以得到控制， 即通过控制光轴与 X轴的角度， 可以控制电磁的 出射位置。 图 4所示为本发明第二实施的超材料功能层的结构示意图， 与实施例一不同 的是， 本实施例中， 每一片层 1上的单元格 4的光轴方向不平行， 呈依次旋转 形态， 如图 4所示， 片层 1折射率最大的位置其光轴方向 （图中波传播椭球的 短轴方向）与 X轴方向的夹角为 0度。 片层 1折射率最小的位置， 光轴方向与 X 轴方向的夹角为 90度。 本实施例中， 由于每一列的单元格的折射率规律相同， 因此，每一单元格都对电磁波有偏折作用（使得电磁波始终向同一个方向偏折）， 电磁波通过多个单元格后， 偏折效果得到累加， 并且由于每个单元格各向异性 的特性， 使得电磁波的出射位置可以得到控制， 例如可以使得电磁波更加的收 拢， 达到能量更为集中的目的。 即利用各向异性的偏折技术来偏折电磁波， 比 单纯的利用折射的非均匀（各向同性的非均匀）来实现偏折， 具有附加的效果， 例如使得电磁波更加的发散、 更加的收拢或是使得电磁波偏折的同时， 实现电 磁波的分裂。
本发明的功能层 10的片状基板 2可以采用陶瓷材料、 高分子材料、 铁电材 料、 铁氧材料或铁磁材料制成。 上述的高分子材料可以是聚四氟乙烯。 聚四氟 乙烯的电绝缘性非常好， 因此不会对电磁波的电场产生干扰， 并且具有优良的 化学稳定性、 耐腐蚀性， 使用寿命长， 作为金属微结构附着的基材是很好的选 择。 当然， 上述的高分子材料也可是 FR-4、 F4b等复合材料。
本发明的人造微结构， 优选地， 采用金属微结构， 所述金属微结构为具有一 定图案的金属线。 例如， 铜线或银线等金属线。 上述的金属线可以通过蚀刻、 电镀、 钻刻、 光刻、 电子刻或离子刻的方法附着在片状基板上。 当然， 也可以 采用三维的激光加工工艺。
另外， 图 1至 4采用的是 I形的人造微结构， I形是各向异性的一种比较简单 的结构， 除此之外， 本发明的人造微结构还可以是如图 6所示的平面雪花状结 构。 当然， 不管是 I形人造微结构， 还是如图 6所示的平面雪花叛乱的人造微结 构， 只要其具有各向异性 （非旋转 90度对称的图形） 的特性即可。
我们知道， 当电磁波在同一介质传播时， 基本没有能量的损失； 而当电磁波 经过不同介质的分界面时， 会发生部分反射现象。 通常两边介质的阻抗差距越 大反射就会越大。 由于部分电磁波的反射， 沿传播方向的电磁能量就会相应损 耗， 严重影响电磁信号传播的距离和传输信号的质量。
因此， 本发明中， 如图 5所示， 在上述的两个实施例中， 所述超材料还可以 包括设置在功能层 10入射面和 /或出射面上的阻抗匹配层。优选地， 在入射面和 出射面上都设有阻抗匹配层 （201， 202)。 本发明通过以下方法实现阻抗匹配， 即， 位于入射侧的阻抗匹配层 201 的与入射侧介质 （例如空气） 相接触的那一 侧的阻抗与入射介质的阻抗接近， 而入射侧阻抗匹配层 201的靠近功能层 10的 一侧其阻抗与功能层 10的入射侧阻抗接近， 且入射侧阻抗匹配层 201的阻抗沿 垂直于功能层的方向其阻抗连续变化。 而位于出射侧的阻抗匹配层 202 与出射 侧介质 （例如空气） 相接触的那一侧的阻抗与出射介质接近， 而出射侧阻抗匹 配层 202的靠近功能层 10的一侧其阻抗与功能层 10的出射侧阻抗接近， 且出 射侧阻抗匹配层的阻抗沿垂直于功能层的方向其阻抗连续变化。 我们知道， 不 同介质分界面其阻抗差值越大，反射越强，因此，通过上述的阻抗匹配层（201， 202)， 可以消除阻抗突变， 进而消除电磁波经过不同介质分界面时的反射现象 以及电磁波能量损耗问题。
上述的阻抗匹配层也可以是一种超材料， 其与功能层有类似的结构。 当然也 可以是其它具有类似功能的材料。 另外， 本文所说的阻抗指的是波阻抗。
由公式阻抗 Z= ^，我们知道只要改变磁导率与介电常数的比值， 就可以 改变阻抗。 因此， 在阻抗匹配层的磁导率均匀分布的情况下， 通过介电常数的 分布可以实现阻抗匹配层内部阻抗分布， 也就是说阻抗匹配层内部的阻抗分布 是可以人为设计的。
结合图 7至图 11对第三实施例和第四实施例进行详细描述。
超材料整体可看成多个立方体结构单元沿三维 X-Y-Z方向叠加而成。 由于超 材料自身需对电磁波产生影响， 因此要求立体结构单元的尺寸小于所需响应的 电磁波波长的五分之一。 优选地， 每一立方体结构单元的尺寸相等且均为所需 响应的电磁波波长的十分之一。
超材料对电磁场的响应主要取决于各个立方体结构单元对电磁场的响应， 当 立方体结构单元数量足够多时， 每个立方体结构单元对电磁场的响应将会叠加 从而从宏观上改变入射电磁波的各个物理特性。
本领域普通技术人员可知， 一束电磁波入射到介质上后会向介质之中折射率 大的地方偏折， 因此要实现电磁波的偏折， 本发明实现电磁波偏折的超材料需 至少沿一个方向如 X方向其折射率是逐渐变化的， 而 Y方向和 Z方向中的任一 方向其折射率不变或者也逐渐变化。 要使偏折的角度大， 则折射率在该方向上 的逐渐减小的变化率要大。 本文的逐渐减小， 是指下一参考点的数据小于或等 于前一参考点的数据。 这里的变化率大， 是指三个前后排列的参考点中， 第二 参考点与第三参考点的差值大于第一参考点与第二参考点的差值。 本文的折射 率， 是由公式 n = " 推算得出的， 其中 α为一个常数， ε为一个超材料立方体 结构单元在某一电磁波频率下的介电常数， μ为此超材料立方体结构单元在该电 磁波频率下的磁导率。 改变各点的介电常数和磁导率即可最终达到本发明偏折 电磁波的目的。
达到改变各点的介电常数和磁导率并使得电磁波偏折的实施方式有多种。 下 面详细论述两种能够达到本发明目的的实施方式。 两种实施例均以 Υ方向为第 一方向， 并且沿 Υ方向超材料折射率的变化趋势是逐渐减小来说明本发明设计 原理。
如图 7、 图 8、 图 9所示， 图 7为本发明实现电磁波偏折的超材料第三实施 例立方体结构单元示意图、图 8为本发明第三实施例由立方体结构单元沿 Χ-Υ-Ζ 方向堆叠而成的超材料结构示意图、 图 9为本发明第三实施例主视图。 图 9中 立方体结构单元包括基材 11、 在基材 11中形成的小孔 20， 小孔 20可以为通孔 也可以不是通孔但其都占据基材 11一定体积。 本实施例中超材料立方体结构单 元基材中形成的小孔 20的体积所占基材 11体积的比值沿 Υ方向逐渐增大， 沿 X和 Ζ方向保持不变从而导致折射率沿 Υ方向逐渐减小， 当电磁波通过超材料 后电磁波的传播方向即向折射率大的地方偏折。
另外， 小孔 20 中可填充介质以改变立方体结构单元的介电常数和磁导率。 由于本实施例主要是通过改变小孔 20占立方体结构单元的体积大小来改变介电 常数和磁导率， 因此本实施例中填充于各小孔 20的介质是相同的但不同于基材 材质， 其可为空气、 陶瓷、 高分子材料、 铁电材料或铁氧材料等。 本实施例中 填充的介质为空气。 由于空气折射率肯定小于基材折射率， 因此小孔 20所占立 方体结构单元的体积比值变化趋势仍然是沿 γ方向逐渐增大使得超材料整体折 射率沿 Y方向逐渐减小。但是当小孔 20中填充的介质的折射率大于基材折射率 时， 小孔 20体积越大将导致立方体结构单元折射率越大， 因此此时小孔 20所 占立方体结构单元的体积比值变化趋势为沿 Y方向逐渐减小使得超材料整体折 射率沿 γ方向逐渐增大。
改变小孔 20占立方体结构单元的体积有不同的实施方式。 图 7、 图 8、 图 9 所示的即为第一实施方式。
图 10为改变小孔 20占立方体结构单元体积的第二实施方式主视图。 立方体 结构单元基材中上形成有多个小孔 20， 沿 Y方向排布的多个立方体结构单元基 材中的小孔 20的数量逐渐增多从而增大小孔 20所占立方体结构单元的体积比 值。 采用改变小孔 20数量的方法来改变其所占立方体结构的体积使得超材料整 体折射率更易于调节， 并能节省打孔模具的开模费用。 与第一实施方式相同的 是， 该些小孔 20内仍可填充不同于基材材质的介质， 本实施方式中填充介质为 空气。 由于空气折射率肯定小于基材折射率， 因此立方体结构单元的小孔 20数 量变化趋势仍然是沿 Y方向逐渐增多使得超材料整体折射率沿 Y方向逐渐减小。 但是当小孔 20中填充的介质的折射率大于基材折射率时， 小孔 20数量越多将 导致立方体结构单元折射率越大， 因此此时立方体结构单元的小孔 20数量变化 趋势为沿 Y方向逐渐减少使得超材料整体折射率沿 Y方向逐渐增大。
可以想象地， 各类小孔 20的横截面图形不一定是图 9、 图 10所表现出来的 圆形， 亦可往为方形、 三角形、 梯形等各类图形， 只要满足本实施例的设计思 想即沿一方向小孔 20所占立方体结构单元的体积比值逐渐变化即可。 同理， 若想沿 X方向和 Z方向均达到偏折电磁波的效果， 只需应用沿 Y方 向立方体结构单元中小孔 20的分布趋势即可。
图 11为本发明实现电磁波偏折的超材料的第四实施例主视图。本实施例中， 立方体结构单元基材中的小孔 20体积所占立方体结构单元体积的比值相同。 小 孔 20既可以是数量相同、 尺寸相同、 横截面图案相同， 也可以是数量不同、 横 截面图案不同或尺寸不同， 但只需要满足所有立方体结构单元基材中所有的小 孔 20体积所占立方体结构单元体积的比值均相同即可。 本实施例中， 以立方体 结构单元基材中的小孔 20 数量相同， 均为一个， 尺寸相同， 横截面图案相同， 均为圆形来作为较佳实施方式。 本实施方式中， 依然以 Y方向为第一方向， 仅 描述折射率沿 Y方向逐渐减小的实施方式， 沿 X、 沿 Z或者沿三者的混合方向 折射率逐渐减小的实施方式可由沿 Y方向折射率逐渐减小的实施方式轻易推出。
由于本实施方式中，各小孔 20占立方体结构单元的体积比例相同，因此沿 Y 方向排布的多个立方体结构单元的小孔 20内需填充不同的介质以改变立方体结 构单元的介电常数和磁导率。 要达到沿 Y方向折射率逐渐减小的目的需在沿 Y 方向一列立方体结构单元的小孔 20 内填充介电常数和磁导率逐渐减小的介质。 例如依次填充碘晶体、 氧化铜、 水晶、 石英、 聚苯乙烯、 氯化钠、 玻璃、 空气。 图 11 中小孔 20中的阴影表示填充的介质， 阴影密度越大表示该填充介质折射 率越大。
将上述第三实施例的各种实施方式和第四实施例的各种实施方式结合起来 能方便的组合出多种可行的实施例。 例如小孔 20体积所占立方体结构单元体积 不同且小孔 20内还填充有折射率不同的介质等。
下面， 结合图 12至图 18对第五实施例至第九实施例进行详细描述。
本发明涉及一种可以使电磁波传播方向发生偏折的实现电磁波偏折的超材 料， 如图 12所示， 由至少一个超材料片层构成， 当超材料片层有多个时， 其沿 垂直于片层表面的方向堆叠并通过一定的组装或连接方式构成一个立体的整体。 如图 12所示， 每个片层包括片状的基材 2和附着在所述基材 2上的多个人 造微结构 3。 片状基材 2具有前、 后两个相互平行的表面， 使得基材 2为一个等 厚的片体。 在任一平行于片状基材 2前表面的平面上， 设置两个相互垂直的方 向， 其中一个为第一方向 X， 另一个为第二方向 Y， 则垂直于基材 2表面的方 向也即超材料片层 1堆叠的方向为第三方向 Ζ。
基材 2上附着有人造微结构 3， 包括有两种情况： 一种是人造微结构 3为平 面结构， 其附着在基材 2前表面上； 另一种是人造微结构 3为三维立体结构， 其附着在片状基材 2 内部。 每个人造微结构 3通常是由银、 铜等金属丝线组成 的， 也可以由非金属丝线组成。 这些丝线连接被刻在基材 2表面或基材 2内部 并构成一定的几何图形。 将基材 2划分成很多个相等的立方体基材单元， 例如 为长、 宽、 高均为入射电磁波波长的十分之一的立方体， 每个基材单元上附着 有一定数量的人造微结构 3， 构成一个超材料单元 40。 因此每个超材料单元 40 含有一定量的构成人造微结构 3的丝线。
已知一束电磁波入射到介质上会向折射率大的地方偏折， 因此要实现电磁波 的偏折， 本发明的实现电磁波偏折的超材料至少沿一个方向如 X方向其折射率 是逐渐减小的，而 Υ方向和 Ζ方向中的任一方向其折射率不变或者也逐渐减小。 要使偏折的角度大， 则折射率在该方向上的逐渐减小的变化率要大。 本文的逐 渐减小， 是指下一参考点的数据小于或等于前一参考点的数据。 这里的变化率 大， 是指三个前后排列的参考点中， 第二参考点与第三参考点的差值大于第一 参考点与第二参考点的差值。本文的折射率， 是由公式 η = " 推算得出的， 其 中 α为一个常数， ε为一个超材料单元 40在某一电磁波频率下的介电常数， μ 为此超材料单元 40在该电磁波频率下的磁导率。
通过大量的试验和仿真得出规律， 即基材 2上的丝线密度大也即基材单元内 丝线含量高的位置该基材单元整体体现的等效折射率大， 因此要使元件沿 X方 向折射率逐渐减小， 则应该至少沿 X方向其基材单元内的丝线含量逐渐减小。 这里的基材单元可以是常规的体积单位如立方毫米、 立方厘米等， 也可以是任 一自定义的体积大小， 例如上述每个超材料单元 40为一个基材单元， 整个超材 料片层 1既是由数以万计的超材料单元 40构成的。
当每个超材料单元 40含有一个人造微结构 3时，当人造微结构 3的尺寸沿 X 方向逐渐减小， 则其基材单元的丝线含量也逐渐减小， 折射率也逐渐减小， 如 图 12、 图 13所示， 此时， 沿 Y方向每个超材料单元 40具有相同的尺寸大小， Y方向折射率不变。 当然， 本发明的实现电磁波偏折的超材料沿 Y方向可依与 X方向同样的原理实现折射率逐渐减小， Z方向亦然。
当各个超材料单元 40所含的人造微结构 3数量不等时，若每个人造微结构 3 的形状、 尺寸完全相同， 可以设计实现电磁波偏折的超材料使其沿 X方向各超 材料单元 40的人造微结构 3数量逐渐减小来实现丝线含量逐渐减少进而折射率 逐渐减小。 Y方向和 Z方向亦然。
本发明的人造微结构 3可以是任何形状的结构。 对于平面结构， 人造微结构 3可以是如图 12、 图 13所示的 "工"字形， 包括相互平行且相等的两个第一金 属丝 50、 两端分别连接在所述两第一金属丝 50 中点且垂直于所述第一金属丝 50的第二金属丝 51 ; 人造微结构 3也可以是 "十"字形， 如图 14所示， 包括 垂直相交的两根长金属丝 60和分别连接在每个长金属丝 60两端且与之垂直的 短金属丝 61 ; 人造微结构 3还可以是具有缺口的圆环， 如图 15所示。 当然， 其 他任意形状如封闭或者不封闭的平面曲线， 例如三角形、 四边形、 "匚"字形、 椭圆环等， 都可以作为本发明的人造微结构 3的丝线所构成的形状。
对于三维立体的人造微结构 3， 其优选实施例如图 16至图 17所示， 本实施 例的实现电磁波偏折的超材料包括多个相同超材料片层 1，即 Z方向的折射率不 变。 对于每个超材料片层 1， 沿 X方向的折射率逐渐减小， Y方向的折射率不 变。 如图 16所示， 由于每个超材料单元 40只含有一个人造微结构 3， 且形状均 相似， 因此， 阵列排布在基材 2内部的人造微结构 3沿 X方向尺寸逐渐减小、 Y方向尺寸不变。 其中， 本实施例的人造微结构 3包括两两垂直且相交于一点 的三根正交金属丝 70和分别垂直连接在每根正交金属丝 70两端且被该正交金 属丝 70平分的端部金属丝 71。
在其他实施例中， 三维的人造微结构 3也有很多种实现方式， 例如图 18所 示的由四根金属丝相接构成的正四面体框， 还可以是其他任意三维结构如任意 空间曲线、 五棱柱框、 圆环等等。
需要说明的是， 本发明的实现电磁波偏折的超材料， 并不限定其所具有的所 有人造微结构 3必然形状相似，各个人造微结构 3可以为各不相同的任意形状， 例如该元件可以同时包括有 "工"字形和圆环形的人造微结构 3 ;
另外， 人造微结构 3并不一定如上述实施例一样比例缩小， 可以通过逐渐减 短人造微结构的某一根或几根丝线从而使超材料单元 40的丝线含量逐渐减少从 而达到折射率逐渐减小的目的， 例如当所有人造微结构均为 "工"字形， 沿 X 方向逐渐减小每一列人造微结构的第二金属丝 51 的长度、 第一金属丝 50长度 不变， 沿 Y方向、 Z方向的各个人造微结构均相同。 这种设计也可实现折射率 沿 X方向逐渐减小、 Y方向和 Z方向折射率不变的目的；
本发明的实现电磁波偏折的超材料使用超材料技术来实现， 超材料是由多个 超材料片层构成的， 改变每个超材料片层上的人造微结构即可改变相应部位的 折射率， 因此通过统一设计各个人造微结构的具体形状和结构即可得到有序变 化的折射率， 从而形成非均匀材料， 进而实现电磁波的偏折。 可见， 本发明的 实现电磁波偏折的超材料可自由设计和组合， 可以满足各种电磁波偏折条件的 要求。
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、一种实现电磁波偏折的超材料， 其特征在于，所述超材料包括一功能层， 所述功能层包括多个相互平行的片层， 每一所述片层包括片状基板和附着在所 述片状基板上阵列排布的多个人造微结构或在所述片状基板中形成的多个小孔， 所述片状基板包括多个单元块， 每一所述人造微结构或所述小孔与其所占据的 所述单元块构成一个单元格， 每一所述片层沿第一方向排布的多个所述单元格 的折射率逐渐变化。
2、 根据权利要求 1 所述的实现电磁波偏折的超材料， 其特征在于， 每一所 述片层沿所述第一方向排布的多个所述单元格的折射率逐渐变小， 每一所述片 层沿垂直于所述第一方向的第二方向排布的多个所述单元格的折射率相同或逐 渐减小， 所述超材料沿垂直于所述片层表面的第三方向排布的多个所述单元格 的折射率相同或逐渐减小。
3、 根据权利要求 2所述的实现电磁波偏折的超材料， 其特征在于， 每一所 述片层上的多个所述人造微结构具有相同的图案， 并且沿所述第一方向排布的 多个所述人造微结构的尺寸逐渐减小， 每一所述片层沿所述第二方向排布的多 个所述人造微结构的尺寸相同或逐渐减小， 每一所述片层沿所述第三方向排布 的多个所述人造微结构的尺寸相同或逐渐减小。
4、 根据权利要求 3 所述的实现电磁波偏折的超材料， 其特征在于， 所述人 造微结构具有非 90度旋转对称的图形， 所述人造微结构为平面的 I形结构或平 面雪花状结构。
5、 根据权利要求 2所述的实现电磁波偏折的超材料， 其特征在于， 每一所 述单元格具有各向异性的电磁参数。
6、 根据权利要求 2所述的实现电磁波偏折的超材料， 其特征在于， 每一所 述人造微结构为构成几何图形的丝线， 附着在所述片状基板上的所述丝线数量 和尺寸沿所述第一方向逐渐减小， 以使每一所述片层沿所述第一方向排布的多 个所述单元格的折射率逐渐减小。
7、 根据权利要求 6所述的实现电磁波偏折的超材料， 其特征在于， 每个所 述人造微结构完全相同， 附着在所述片状基板上的所述人造微结构的数量不完 全相同。
8、 根据权利要求 6所述的实现电磁波偏折的超材料， 其特征在于， 所述人 造微结构为平面的 "工"字形， 包括相互平行且相等的两个第一金属丝、 两端 分别连接在所述两第一金属丝上且垂直于所述第一金属丝的第二金属丝。
9、 根据权利要求 6所述的实现电磁波偏折的超材料， 其特征在于， 所述人 造微结构为 "十"字形、 具有缺口的圆环或封闭曲线。
10、 根据权利要求 6所述的实现电磁波偏折的超材料， 其特征在于， 所述人 造微结构为三维结构， 包括两两垂直且相交于一点的三根正交金属丝和分别垂 直连接在每根所述正交金属丝两端的端部金属丝。
11、 根据权利要求 2所述的实现电磁波偏折的超材料， 其特征在于， 每一所 述片层沿所述第一方向排布的多个所述单元格的光轴平行或依次旋转。
12、 根据权利要求 1所述的实现电磁波偏折的超材料， 其特征在于， 沿所述 第一方向排布的多个所述单元格中的所述小孔体积与所述单元格体积的比值逐 渐变化， 且所述小孔内填充的介质相同， 使得每一所述片层沿所述第一方向排 布的多个所述单元格的折射率逐渐变化。
13、 根据权利要求 12所述的实现电磁波偏折的超材料， 其特征在于， 每一 所述单元格中形成一所述小孔， 沿所述第一方向排布的多个所述单元格的所述 小孔的尺寸逐渐变化。
14、 根据权利要求 12所述的实现电磁波偏折的超材料， 其特征在于， 每一 所述单元格中形成多个体积相同的所述小孔， 沿所述第一方向排布的多个所述 单元格的折射率逐渐变化。
15、 根据权利要求 12所述的实现电磁波偏折的超材料， 其特征在于， 所述 小孔内填充所述介质的折射率小于所述片状基板的折射率， 沿所述第一方向排 布的多个所述单元格中的小孔体积与所述单元格体积的比值变化趋势与所述超 材料整体的折射率变化趋势相反。
16、 根据权利要求 12所述的实现电磁波偏折的超材料， 其特征在于， 所述 小孔内填充所述介质的折射率大于所述片状基板的折射率， 沿所述第一方向排 布的多个所述单元格中的小孔体积与所述单元格体积的比值变化趋势与所述超 材料整体的折射率变化趋势相同。
17、 根据权利要求 1所述的实现电磁波偏折的超材料， 其特征在于， 沿所述 第一方向排布的多个所述单元格中的所述小孔体积与所述单元格体积的比值相 同， 且所述小孔内填充的介质不同， 使得每一所述片层沿第一方向排布的多个 所述单元格的折射率逐渐变化。
18、 根据权利要求 17所述的实现电磁波偏折的超材料， 其特征在于， 沿所 述第一方向排布的多个所述单元格中的所述小孔填充的所述介质为折射率逐渐 变化的介质。
19、 根据权利要求 1所述的实现电磁波偏折的超材料， 其特征在于， 所述单 元格尺寸小于所需偏折的电磁波波长的五分之一。
20、 根据权利要求 1所述的实现电磁波偏折的超材料， 其特征在于， 所述超 材料还包括设置在功能层入射面和 /或出射面上的阻抗匹配层； 所述片状基板的 制造材料包括陶瓷材料、 高分子材料、 铁电材料或铁氧材料。
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