A kind of negative-magnetic-permeability meta-material
Technical field
The present invention relates to Meta Materials field, relate to a kind of negative-magnetic-permeability meta-material particularly.
Background technology
At present, international community has large quantifier elimination to magnetic permeability aspect, research wherein for positive magnetic permeability has been tending towards ripe, research for negative-magnetic-permeability meta-material is the focus of research both at home and abroad now, negative magnetoconductivity has quantum polarization, polarization can be produced to incident wave, therefore sphere of action is very large, as the mr imaging technique in medical imaging field, negative magnetic-inductive capacity material can strengthen electromagnetic imaging effect, negative magnetic-inductive capacity material also plays an important role in lens research in addition, at engineering field, magnetic permeability all refers to relative permeability usually, for absolute permeability μ and the magnetic constant μ of material
0the ratio of (also known as permeability of vacuum), μ
r=μ/μ
0, dimensionless number.Usually " relatively " two word and symbol subscript r be all removed.Magnetic permeability is when representing that material is subject to magnetizing field H effect, the increase (μ > 1) of inner true magnetic field relative to H or the degree of minimizing (μ < 1).So far, in the already present material of the nature found, μ is greater than 0.
Meta Materials refers to some artificial composite structures with the extraordinary physical property not available for natural material or composite material.By the structurally ordered design on the key physical yardstick of material, the restriction of some apparent natural law can be broken through, thus obtain the meta-materials function exceeding the intrinsic common character of nature.The character of Meta Materials and function mainly come from the structure of its inside but not form their material.At present, the geometry of existing man-made microstructure is the open annular of " work " font or similar " recessed " font as shown in Figure 1, but this structure all can not realize magnetic permeability μ and be significantly less than 0 or make meta-material resonant frequency significantly reduce, only has the man-made microstructure by design with special geometric figure, just can make this artificial electromagnetic material in special frequency channel, reach magnetic permeability μ value and be less than 0, and there is lower resonance frequency.
Summary of the invention
Technical problem to be solved by this invention is, is anisotropy and the narrower situation of resonant frequency range, provides the isotropism negative-magnetic-permeability meta-material that a kind of frequency point ranges is wider for negative-magnetic-permeability meta-material in prior art.
The technical scheme that the present invention realizes goal of the invention employing is, described Meta Materials comprises medium substrate and is fixed on the man-made microstructure on medium substrate, described man-made microstructure forms by four Archimedes spirals are equidistantly nested from inside to outside, and described man-made microstructure is around the starting point half-twist of arbitrary Archimedes spiral, overlap with initial man-made microstructure after 180 °, 270 °.
In negative-magnetic-permeability meta-material of the present invention, the live width 0.05-0.15mm of described Archimedes spiral.
In negative-magnetic-permeability meta-material of the present invention, the distance between centers of tracks 0.05-0.15mm of described Archimedes spiral.
In negative-magnetic-permeability meta-material of the present invention, the thickness 0.015-0.020mm of described Archimedes spiral.
In negative-magnetic-permeability meta-material of the present invention, the medium substrate of described Meta Materials is FR-4 substrate or ceramic substrate.
In negative-magnetic-permeability meta-material of the present invention, the dielectric constant of described FR-4 substrate is 4.2-4.6, and the dielectric constant of described ceramic substrate is 8-16.
In negative-magnetic-permeability meta-material of the present invention, described medium substrate is divided into multiple identical cube medium substrate unit, each medium substrate unit is attached with a man-made microstructure.
In negative-magnetic-permeability meta-material of the present invention, described medium substrate unit is along vertical x, y, z three the direction array arrangements of pairwise orthogonal.
In negative-magnetic-permeability meta-material of the present invention, the number of turns of described four spiral of Archimedes spirals is equal and be all not less than 1.
Beneficial effect of the present invention is, man-made microstructure forms by four Archimedes spirals are equidistantly nested from inside to outside, the characterisation of structures of helical length can be equivalent to inductance, adjacent two helicals can be equivalent to electric capacity, helical winding turns increases, helical length increases thereupon, then inductance increases, electric capacity increases, Meta Materials of the present invention is while realizing negative magnetoconductivity, and corresponding resonance frequency will reduce, according to the shape of man-made microstructure, Meta Materials of the present invention is isotropism, has good development prospect.
Accompanying drawing explanation
Fig. 1, existing negative-magnetic-permeability meta-material man-made microstructure schematic diagram;
Fig. 2, preferred embodiment of the present invention Meta Materials schematic diagram;
Fig. 3, preferred embodiment of the present invention metamaterial unit schematic diagram;
Fig. 4, preferred embodiment of the present invention man-made microstructure schematic diagram;
Fig. 5, Archimedes spiral schematic diagram;
Fig. 6, the magnetic permeability simulated effect schematic diagram of existing negative-magnetic-permeability meta-material;
Fig. 7, the magnetic permeability simulated effect schematic diagram of the preferred embodiment of the present invention;
In figure, 1 man-made microstructure, 2 medium substrates, 3 medium substrate unit, 10 metamaterial unit.
Embodiment
Below in conjunction with drawings and Examples, the present invention is described in detail.
The invention provides a kind of negative-magnetic-permeability meta-material, as shown in Figure 2, comprise medium substrate 2 and be fixed on the man-made microstructure 1 on medium substrate, to be that four Archimedes spirals are equidistantly nested from inside to outside form man-made microstructure 1, man-made microstructure 1 is around the starting point half-twist of arbitrary Archimedes spiral, overlap with initial man-made microstructure after 180 °, 270 °, the schematic diagram of man-made microstructure 1 of the present invention is see Fig. 4, and the micro-structural of this shape can make Meta Materials be isotropism.
Here Archimedes spiral refers to, for the P of in plane along moving ray OP with while rate motion such as grade, this ray rotates around O with constant angular velocity again, and the track of some P is called Archimedes spiral.The wire-shaped that the present invention forms man-made microstructure is Archimedes spiral, from Fig. 5 Archimedes spiral schematic diagram, if O
efor the limit of polar coordinate system, O
ebe the pole axis of polar coordinate system with the line of an end points of Archimedes spiral, then all available polar coordinates (ρ of any point on this helical
e, θ) represent, wherein ρ
efor the footpath, pole of this point, θ is the polar angle of this point, ρ
e(θ) represent the extremely long function about polar angle, Archimedes spiral meets following condition: 1) ρ
e=a θ; 2) distance of the every arm of this helical equals 2 π a forever, and a is constant, and in the present invention, the starting point of Archimedes spiral is the limit O of polar coordinate system
e, according to the demand of frequency realizing negative magnetoconductivity, the number of turns of Archimedes spiral coiling can be controlled, namely increases winding turns, then reduce the resonance frequency that Meta Materials realizes negative magnetoconductivity.
As shown in Figure 1, the number of turns of existing single radial cut resonant ring is not more than 1.A circle herein, refers to as shown in Figure 5, and any of the ring-shaped inner part surrounded with split ring resonator is polar limit O
e, from limit O in split ring resonator two distal point
enear distal point line is to the extreme this polar pole axis, and getting is positive direction counterclockwise, then use polar coordinates (ρ successively along the every bit on split ring resonator
e, θ) represent, every one 360 degree is a circle, until reach split ring resonator from another distal point away from limit.
The medium substrate 2 of negative-magnetic-permeability meta-material of the present invention can be divided into identical multiple cube shaped medium substrate unit 3 by virtual, medium substrate 2 can be regarded as by multiple such medium substrate unit 3 with x direction be row, y direction is row, the array that forms for stacked direction of z direction, wherein x, y, z direction pairwise orthogonal is vertical.Medium substrate 2 can be made up of FR-4, F4b, CEM1, CEM3 and TP-1 ceramic material, if use the substrate of FR-4 grade, its dielectric constant is 4.2-4.6, if use ceramic substrate, its dielectric constant is 8-16.The medium substrate of embodiment of the present invention negative-magnetic-permeability meta-material selects the epoxy resin base plate of FR-4 grade, and dielectric constant is 4.4, and thickness is 0.4mm.
Each medium substrate unit 3 is fixed with a man-made microstructure 1, man-made microstructure 1 on medium substrate unit 3 and medium substrate unit 3 forms metamaterial unit 10 jointly, as shown in Figure 3, therefore the present invention can be regarded as and formed along x, y, z three direction array arrangements by multiple metamaterial unit 10.
Man-made microstructure 1 is generally metal wire, as copper cash, silver-colored line, copper alloy, or even gold thread, also can be by least two kinds of metal alloys, or even nonmetallic electric conducting material, as conductive plastics, ITO(indium tin oxide), carbon nano-tube, graphite etc., the live width of metal wire controls at 0.05-0.15mm, the distance between centers of tracks of metal broken line controls at 0.05-0.15mm, and the THICKNESS CONTROL of metal wire is at 0.015-0.020mm.Man-made microstructure of the present invention all has response to magnetic field, and between its two just right broken lines to walk distance between centers of tracks d equal, minimumly at present 0.1mm can be accomplished, the man-made microstructure of prior art to magnetic responsiveness is generally opening resonance loop structure, as shown in Figure 1, this structure is similar to unsealed " recessed " font micro-structural.
Below in conjunction with accompanying drawing, the principle of compositionality of the negative-magnetic-permeability meta-material of the embodiment of the present invention and beneficial effect are elaborated.
Man-made microstructure 1 is periodic arrangement on the surface of medium substrate 2, such as rectangular array arrangement, namely with an x direction be row, with perpendicular to the y direction in x direction be row arrange, and each line space, each column pitch are respectively equal, and even line space equals column pitch.Preferred line space, column pitch are not more than 1/5th of the wavelength of the incident electromagnetic wave that will respond, the i.e. electromagnetic wave of such as operational environment to be wavelength be λ, Meta Materials is needed to be present negative magnetoconductivity to this electromagnetic electromagnetic property, when then designing man-made microstructure, above-mentioned line space, column pitch are selected to be not more than λ/5, be preferably λ/10.Obviously, in order to make man-made microstructure 1 not overlapping mutually, length and the width of each man-made microstructure 1 are also not more than λ/5.Periodic arrangement can also have other to have the arrangement mode of circulation law, such as when medium substrate 2 is circular or polygon time, man-made microstructure 1 is along the external cylindrical surface of circular or polygon substrate 2 equally spacedly around one week, and embodiment of the present invention medium substrate 2 is rectangle, see Fig. 2.
The principle that the present invention realizes negative magnetoconductivity is, for micro-structural of the present invention, can be equivalent to LC oscillating circuit, whole Archimedes spiral can be equivalent to the electric capacity that a pole plate length approximates helical total length, every two sections of pole plates facing helical mutually and be equivalent to electric capacity, helical length characterisation of structures can be equivalent to inductance, found by emulation, in the immovable situation of other conditions, copper cash is longer, the number of turns that helical rotates is more, then the equivalent inductance value of structure, capacitance are larger.
By LC oscillating circuit formula
known, when inductance value, capacitance all increase, the resonance frequency of its correspondence then reduces.
Prior art directly will not seal " recessed " shape split ring resonator array arrangement on medium substrate shown in Fig. 1, make Meta Materials, the present invention is from any outside equidistantly spiral by a broken line, form man-made microstructure, for comparing the difference of prior art and negative-magnetic-permeability meta-material performance of the present invention, with CST, prior art negative-magnetic-permeability meta-material and preferred embodiment of the present invention negative-magnetic-permeability meta-material are emulated respectively, Meta Materials in prior art is set identical with the structural parameters of the embodiment of the present invention Meta Materials during emulation, in simulation process, embodiment of the present invention concrete structure parameter is as follows: copper cash live width 0.1mm, copper cash distance between centers of tracks 0.1mm, coiling 1 is enclosed, copper cash thickness 0.164mm, the thickness of FR-4 grade epoxy resin base plate 3 is 0.164mm, dielectric constant 4.8, Meta Materials man-made microstructure 1 is of a size of 5mm × 5mm.The magnetic permeability of existing negative magnetic conductance Meta Materials about the electromagnetic response curve of frequency see Fig. 6, as shown in Figure 6, prior art will realize magnetic permeability and be less than 0, its respective resonant frequencies is at 400MHz, magnetic permeability simulated effect schematic diagram of the present invention is see Fig. 7, as shown in Figure 7, it is negative that Meta Materials of the present invention all can realize Meta Materials magnetic permeability between 2GHz-2.8GHz, expand the range of choice of negative-magnetic-permeability meta-material frequency range, meanwhile, can also by the frequency regulating the size of artificial micro-structure metal wound coil number or convergent-divergent man-made microstructure to regulate negative magnetoconductivity.
Superior part of the present invention is, design a kind of brand-new man-made microstructure 1, as shown in Figure 4, this man-made microstructure 1 not only makes negative-magnetic-permeability meta-material of the present invention be isotropism, and all can to realize Meta Materials magnetic permeability between 2GHz-2.8GHz be negative, increase or reduce the winding turns of Meta Materials, obtain the frequency needed, this novel low-frequency negative-magnetic-permeability meta-material is for Meta Materials industrial expansion, significant.
Above-described embodiment in the present invention has only done exemplary description; those skilled in the art can carry out various amendment and retouching to the present invention without departing from the spirit and scope of the present invention after reading present patent application, and these amendments and retouching all belong to protection scope of the present invention.