201 results about "Broadband absorption" patented technology

The invention provides a conductive foam filled aramid honeycomb wave-absorbing composite material as well as a preparation method and application thereof, and belongs to the technical field of advanced materials. The aramid fiber honeycomb wave-absorbing composite material is prepared by pressing a mixture obtained by mixing thermal expansion microspheres and multi-walled carbon nanotubes into aramid fiber honeycomb holes and foaming. The wave-absorbing composite material prepared by the invention has the characteristic of broadband absorption and is excellent in wave-absorbing effect; meanwhile, compared with an existing filling and dipping process, the preparation method does not involve addition and blending of any reagent, the production cost can be saved, and the preparation process can be simplified; the aramid honeycomb holes are completely and uniformly filled, the aramid honeycomb material is not processed and damaged in the preparation process, and the mechanical bearing capacity of the prepared wave-absorbing composite material is obviously enhanced compared with that of the wave-absorbing composite material prepared by a traditional dipping or filling process. Therefore, the wave-absorbing composite material and the preparation method thereof have wide application prospects in the field of electromagnetic wave stealth.

The invention discloses a metasurface wave absorber based on a square and round multi-nested structure. The structure is composed of a top metal resonance layer, a dielectric layer and a bottom metal layer. The wave absorber is composed of a periodic unit structure, and a resonance layer of the wave absorber is composed of a split circular ring, a split square ring, a metal wafer and eight chip resistors. The split circular ring is distributed on the outermost periphery of the resonance layer, a certain distance is kept between the split circular ring and the boundary of the resonance unit, and chip resistors with the resistance value of 250 ohms are welded to the four split positions of the circular ring; the split square ring is arranged on the inner side of the circular ring and keeps a certain distance from the circular ring, and 300-ohm chip resistors are welded at four split positions; the inner side of the split circular ring is provided with a metal disc and keeps a certain distance from the square ring. The metasurface wave absorber is low in manufacturing cost and simple in structure, the electromagnetic wave absorption rate can reach 90% or above at 10.15 GHz-20.91 GHz, and the metasurface wave absorber has the very good broadband absorption characteristic.

The invention relates to the field of super-hydrophobic materials, in particular to a basalt fiber composite material as well as a preparation method and application thereof. According to the composite fabric material provided by the invention, a multistage micro-nano rough surface of the MoS2 nanoflowers and the silver nanoparticles is constructed on the fiber substrate, so that not only is super-hydrophobic self-cleaning realized, but also the anti-icing performance is relatively high, and particularly, rapid heating is realized by combining broadband absorption of the MoS2 nanoflowers and a local surface plasma resonance effect of the silver nanoparticles; and meanwhile, the silver nanoparticles accelerate heat conduction, so that excellent ice melting capability is obtained. The high conductivity of the silver nanoparticles constructs a conductive path, and the layered structure of MoS2 triggers interface polarization, so that the electromagnetic shielding effectiveness of the X wave band is improved. The dual antibacterial mechanism of the MoS2 nanoflowers and the silver nanoparticles also realizes broad-spectrum efficient antibiosis, the preparation method is green and environment-friendly, the cost is low, and the requirements of complex scenes such as wearable electronic equipment, medical protection, polar region protection and national defense can be met.

The invention discloses a metasurface array antenna housing, belongs to the technical field of electromagnetic wave regulation and control, and solves the problem of how to improve the transmittance and absorptivity of a metasurface to electromagnetic waves. Electromagnetic waves with different frequencies resonate on the first metasurface wave-absorbing layer and the second metasurface wave-absorbing layer respectively, so that the electromagnetic waves are absorbed by the lumped resistor. And the metasurface wave-transmitting layer re-radiates electromagnetic waves of a communication frequency band to enable the electromagnetic waves to penetrate through the metasurface unit, and meanwhile, the surface of the metasurface wave-transmitting layer can serve as a metal floor of the first metasurface wave-absorbing layer and the second metasurface wave-absorbing layer due to copper coating. The antenna can be widely used in the scenes of radar stealth, communication antenna integration, electromagnetic compatibility, wireless energy transmission and the like, and has a good application prospect.

The invention provides a high-frequency band-pass radar and infrared dual-stealth optical transparent metamaterial, and aims to overcome the defect that an existing stealth material cannot have optical transparency, infrared low emission, microwave broadband absorption and high-frequency band-pass at the same time. The antenna is formed by periodically arranging a plurality of structural units, and each structural unit sequentially comprises a low infrared emission layer, a first transparent dielectric substrate, a radar wave absorbing layer, a second transparent dielectric substrate and a frequency selection wave-transparent layer from top to bottom; the low infrared emission layer and the radar wave absorbing layer are respectively composed of a square patch array made of a transparent conductive material and a low duty ratio circular ring; the frequency selection wave-transparent layer is composed of a square ring aperture type metal mesh. Optical transparency, infrared stealth and radar stealth are integrated, meanwhile, the band-pass performance is achieved in the high-frequency guidance wave band, and the high application prospect is achieved in the field of actual engineering.

The invention discloses a multifunctional broadband metamaterial structure with a polarization independent characteristic and a control method. The structure has a switchable tri-state function and a complete polarization operation capability irrelevant to polarization. By introducing the guide circuit design, three different electromagnetic energy regulation and control modes of second-order filtering, broadband absorption and multi-reflection shielding are efficiently integrated in the same structure, the real broadband performance in the band is realized, and meanwhile, the higher reflection efficiency outside the band is kept. Different from a traditional method which depends on a broadband lossless reflecting layer to expand the transmission bandwidth of an absorption structure, the three arrays are considered as an integral operating system, support three-state switching operation and have real broadband and efficient behaviors.

The invention provides an infrared broadband absorber. According to the invention, an efficient absorption structure is formed by introducing the non-antisymmetric Bragg structure layer and the metal material film with relatively high absorption rate. The phase change material and the dielectric material form an antisymmetric Bragg structure, the absorptivity of the device is further improved, and the MgF2 low-refractive-index layer is combined, and the materials and the thickness of each layer are optimized, so that effective reflection suppression and absorption enhancement of light with different wavelengths are realized. Compared with the prior art, the infrared broadband absorber is simple in structure, the absorption effect of 90% or above can be achieved within the ultra-wide range, the relative absorption bandwidth exceeds 152.8%, a great opportunity is provided for ultra-wide spectrum detection, a feasible technical approach is provided for ultra-wide spectrum confrontation and invisibility, and the infrared broadband absorber has the advantages of being high in practicability and wide in application range. And confrontation and stealth on active and passive composite sensing detection equipment are expected to be realized, and the application potential of the material in the fields of infrared absorption, infrared stealth, photothermal conversion, sensing and the like is expanded.

The invention discloses a carbon-based metamaterial electromagnetic wave absorber and a preparation method and application thereof. The wave absorbing body adopts a three-layer composite structure, wherein the bottom layer is a copper plate reflecting layer; the lower layer is of a honeycomb-like structure and is formed by periodically arranging regular octagons and square hollow quadrangular prisms externally connected with the regular octagons, and the adjustable wave absorbing frequency band is achieved by adjusting and controlling the width and height of the hollow cores; the upper layer is of a pointed cone structure, and the impedance matching characteristic is enhanced by optimizing the vertex angle of the regular rectangular pyramid. The wave absorber is made of photosensitive resin, based on the photocuring 3D printing technology, honeycomb-like and pointed cone structures are printed step by step and bonded and combined, and high-precision forming is achieved in combination with parameterized regulation and control. The wave absorber has the advantages of light weight, broadband absorption and adjustable mechanical performance, can be applied to the fields of EMI shielding of electronic equipment, military radar stealth, high-frequency communication protection, electromagnetic environment protection and the like, and remarkably improves the electromagnetic wave absorption and shielding effectiveness through the metamaterial structure design and a multi-component cooperative loss mechanism.

The invention provides a wave-absorbing material, and belongs to the technical field of electromagnetic wave absorption. The wave-absorbing material comprises a metal reflection bottom layer, a wave-absorbing middle layer and a scattering upper layer, the wave-absorbing middle layer is made of a ferroferric oxide loaded reduced graphene oxide and epoxy resin (Fe3O4 (at) RGO / EP) composite material and used for absorbing electromagnetic wave energy, and the scattering upper layer is of a patterned metasurface structure made of chopped carbon fiber reinforced epoxy resin (SCF / EP). And a phase-regulated two-dimensional periodic array is formed. By arranging a three-layer structure of the metal reflecting layer, the Fe3O4 (at) RGO / epoxy composite wave-absorbing layer and the chopped carbon fiber scattering layer, broadband absorption and directional scattering control of electromagnetic waves within the range of 2-18 GHz are achieved, a stealth function composite material system with dissipation and deflection dual-mechanism cooperative work is formed, the structure utilizes the patterning design of the scattering layer, and the structure has the advantages that the structure is simple, the structure is compact, and the application range is wide. On the basis of the generalized Snell's law, engineering regulation and control of the radar wave reflection direction are achieved by regulating and controlling the reflection phase difference between pattern units, reflection energy is effectively deviated from the main lobe direction of a radar receiver, and therefore the reflection signal intensity of a target in a radar detection system is reduced.

The invention belongs to the technical field of mid-infrared photoelectric detectors, and particularly relates to a mid-infrared photoelectric detector based on an ultra-thin metasurface and a preparation method thereof.The method comprises the steps that firstly, a substrate and an element atomic material are provided, an ellipsometry test is conducted to obtain dielectric functions of the substrate and the element atomic material, the dielectric functions serve as input to be substituted into finite element software, and the finite element software serves as the input to obtain the ultra-thin metasurface-based mid-infrared photoelectric detector; theoretical modeling design is carried out on the metasurface, the metasurface is manufactured after the appropriate metasurface size is obtained, then reflectivity and transmissivity tests under different polarizations are carried out on the metasurface through an ellipsometry test, a metal layer is deposited on the metasurface through a standard electron beam evaporation technology to serve as an electrode, and the metasurface is manufactured. And finally, a CO2 laser is selected to irradiate the metasurface in a photoelectric detection experiment. By optimizing the structure parameters and the material performance of the metasurface, middle and far infrared broadband absorption, efficient photo-thermal conversion and photoelectric response are achieved, and therefore the problems that in the prior art, the corresponding wavelength is short, devices are heavy, and the detection efficiency is insufficient are solved.

A broadband low-transmittance and high-absorption wave absorption and transmission integrated frequency selection surface comprises three wave absorption layers and two wave transmission layers which are sequentially stacked from top to bottom, and the three wave absorption layers are sequentially divided into an upper wave absorption layer, a middle wave absorption layer and a lower wave absorption layer from top to bottom; the two wave-transparent layers are sequentially divided into an upper wave-transparent layer and a lower wave-transparent layer from top to bottom; the multi-layer composite structure design is adopted, collaborative optimization of the wave absorbing performance and the wave transmitting performance is achieved by combining the two wave transmitting layers on the lower portion and the three wave absorbing layers on the upper portion, through organic combination of the upper layer structure and the lower layer structure, dual performance improvement of broadband wave absorbing and broadband wave transmitting is achieved, and a transition zone between a wave absorbing zone and a wave transmitting zone is greatly reduced.

The invention provides a display structure. The display structure comprises a narrow-band absorber structure; the broadband absorber structure comprises a thin film composed of a dielectric layer and a metal layer, the metal layer is multi-layer and has loss, the K value is larger than a preset threshold value, and the broadband absorber structure is located on the narrow-band absorber structure and coupled with the narrow-band absorber structure to generate bright colors. The multi-layer metal layer with the high K value is adopted in the broadband absorber structure, the reflectivity of a non-target wave band can be restrained, rich colors are generated, the purity of the colors is improved, and the structural assembly has the advantages of being simple in structure, not prone to being influenced by the environment, insensitive to the angle and the like.

The invention discloses an electromagnetic shielding technical scheme of a coding superstructure and an optimization design system. The electromagnetic shielding technical scheme comprises a reflectivity setting module which sets a reflectivity threshold according to target shielding performance; the superstructure construction module generates an initial candidate array based on the symmetric unit design; and the parameter optimization module dynamically adjusts the sub-block thickness and the unit ratio k value through a particle swarm algorithm, and realizes 1-18GHz broadband reflectivity optimization in combination with a piecewise evaluation function. According to the invention, through deep fusion of coding superstructure design and an intelligent optimization system, collaborative optimization of electromagnetic loss and phase regulation is successfully realized, and significant technical advantages are formed in key indexes such as broadband absorption, angle adaptability, system efficiency and the like.

The invention relates to the technical field of terahertz metamaterial sensors, in particular to a vanadium dioxide-based polarization-insensitive ultra-wideband terahertz metamaterial wave absorber, which consists of a vanadium dioxide resonance layer, a photonic crystal plate dielectric layer and a metal reflecting layer, therefore, the terahertz metamaterial wave absorber formed by the invention is of a metamaterial resonance layer-medium-metal bottom plate structure with a simple configuration. Simulation results show that when VO2 is in a metal state, the wave absorber achieves ultra-wideband absorption within the frequency range of 4.78-13.28 THz, the average absorption rate is as high as 97.5%, the absorption bandwidth is 8.5 THz, and the relative bandwidth is 94.1%. By changing the conductivity of vanadium dioxide, the absorptivity of the wave absorber can be dynamically adjusted between 1.2% and 97.5%. The terahertz ultra-wideband wave absorber has potential application value in the fields of adjustable wideband absorption devices, stealth devices, thermal detection, terahertz switches and the like. In addition, the wave absorber has the characteristics of polarization insensitivity and wide-angle absorption, the practicability of the device in multi-scene application is further improved through the polarization insensitivity characteristic, and the wave absorber has the advantages of being multifunctional and high in reliability.

The invention discloses an ultra-wideband absorber which can be applied to the technical field of microwave metamaterial absorbers. A plurality of periodically arranged unit structures are arranged, an upper layer structure, a middle layer structure and a lower layer structure are arranged in each unit structure, then a PMMA dielectric layer, an I TO resistance film resonance layer and a PET dielectric layer are arranged in each of the upper layer structure, the middle layer structure and the lower layer structure, and the PET dielectric layer is arranged below the PMMA dielectric layer. The I TO resistive film resonance layer is etched on the PET dielectric layer, the I TO resistive film resonance layer in the upper layer structure is set to be a circular square ring gear type pattern, the I TO resistive film resonance layer in the middle layer structure is set to be a polygonal patch type pattern, and the I TO resistive film resonance layer in the lower layer structure is set to be a mesh grid type pattern. Therefore, the functions of ultra-wideband absorption, optical transparency, large-angle incidence, polarization angle polarization insensitivity, easy preparation and low manufacturing cost can be realized.

The invention discloses a polarization sensitive type broadband absorber based on metal-medium stacking, and relates to the technical field of micro-nano photonic devices and infrared detection. The absorber sequentially comprises a bottom-layer high-loss metal reflecting layer, a multi-layer stacked composite dielectric cavity structure and a top-layer sub-wavelength metal grating from bottom to top, according to impedance matching and interference resonance theories, a broadband absorption substrate is constructed through a multi-layer film structure at the bottom, and light energy is converted into heat energy by utilizing the high loss characteristic of bottom layer metal; plasmon resonance is excited through the top metal grating, the coupling efficiency of TM polarized light is enhanced, and TE polarized light is cut off; the above structural design successfully realizes efficient broadband absorption and high polarization extinction ratio in an infrared band. The structure is simple in design, is compatible with a CMOS technology, and has excellent wide-angle stability. And meanwhile, polarization screening can be realized without an external polaroid, and miniaturization and integration of an infrared detection system are facilitated.

The invention provides a broadband wave-absorbing gradient multilayer composite wave-absorbing material and a preparation method thereof.According to the method, a 2D-0D dielectric-magnetic nanocomposite with a heterogeneous coating structure is selected as a functional filler and mixed with a silicone rubber matrix to prepare the broadband wave-absorbing gradient multilayer composite wave-absorbing material, and the concentration of the dielectric material is gradually increased from top to bottom; the invention relates to a gradient structure multilayer composite wave-absorbing material with gradually reduced magnetic material concentration. The effective wave-absorbing bandwidth of the multi-layer composite wave-absorbing material can be effectively widened by regulating and controlling the type, the coating ratio and the mass fraction of the wave-absorbing functional filler and the thickness of the multi-layer composite wave-absorbing material, and the gradient multi-layer composite material with the ultra-wideband absorption characteristic is achieved. Besides, according to the method provided by the invention, the flexible and weather-resistant silicone rubber material is used as a matrix, the multilayer composite wave-absorbing material is prepared in a layer-by-layer pouring and curing mode, the manufacturing process is simple, industrial production is easy, and commercial application with flexible and broadband requirements can be met.

The invention discloses an all-dielectric-based optical transparent terahertz metamaterial broadband absorber, the absorber is composed of periodically arranged absorber unit structures, each unit structure of the absorber is composed of three all-dielectric optical transparent material layers, the top layer is a polydimethylsiloxane layer, the middle layer is a polylactic acid layer, and the bottom layer is an all-dielectric optical transparent material layer. The bottom layer is an indium tin oxide thin film layer, the polydimethylsiloxane layer, the polylactic acid layer and the indium tin oxide thin film layer are of square structures with the same plane period size, an annular opening is formed in the plane center of the polydimethylsiloxane layer, and the inner circle and the outer circle of the annular opening are connected through four connecting arms with the same width. The plane center of the polylactic acid layer is provided with a cross hollow structure, and the polydimethylsiloxane layer, the polylactic acid layer and the indium tin oxide thin film layer jointly form a Fabry-Perot cavity. The invention has optical transparency, has the characteristics of simple structure, high absorptivity, wide incident angle and polarization insensitivity, and is wide in application scene.

The invention aims to provide a broadband polarization insensitive Hertz wave-absorbing material based on ITO (indium tin oxide) resistance loss, belongs to the technical field of large Hertz wave-absorbing materials, and aims to solve the defects of an existing terahertz wave-absorbing material in the aspects of broadband absorption capability, oblique incidence angle adaptability, polarization insensitivity, structural light weight and the like. The wave-absorbing material sequentially comprises four ITO resistance loss layers composed of ITO patch units from top to bottom, and each ITO resistance loss layer adheres to a PET double-sided adhesive layer and is divided through a PS foam dielectric layer. According to the structure, the polarization insensitive characteristic is realized, and the problem that an existing wave-absorbing material depends on the polarization angle is solved.

The invention discloses a negative conical wave-absorbing honeycomb, which comprises a negative conical impedance matching layer, an absorbing layer and a reflecting layer, and is characterized in that the negative conical impedance matching layer, the absorbing layer and the reflecting layer respectively comprise at least one honeycomb layer, and the honeycomb apertures of the negative conical impedance matching layer, the absorbing layer and the reflecting layer are sequentially decreased; the negative tapered impedance matching layer surface includes at least one negative tapered slot. According to the scheme of the invention, when electromagnetic waves are incident to the honeycomb, the negative conical shape design ensures that two surfaces are always in an oblique incidence state in the polarization direction, scattering of the electromagnetic waves is enhanced, reflection is reduced, impedance matching with airwaves is enhanced, the electromagnetic waves are made to be incident into the material to the greatest extent, and the electromagnetic waves are prevented from entering the material to the greatest extent. Multiple times of reflection and refraction of electromagnetic waves in the negative conical structure are increased, electromagnetic wave energy radiated out is effectively reduced, and efficient broadband absorption of the electromagnetic waves is achieved.

The invention discloses a high-entropy double hydroxide / carbon fiber aerogel electromagnetic wave-absorbing material and a preparation method thereof, and the method specifically comprises the following steps: (1) activating green algae to obtain carbon fibers, and freeze-drying the carbon fibers to obtain aerogel carbon fibers; (2) immersing the aerogel carbon fiber subjected to heat treatment into a high-entropy layered double hydroxide precursor solution for hydrothermal reaction, and obtaining a high-entropy double hydroxide / carbon fiber aerogel material after the reaction; wherein the temperature of the hydrothermal reaction is 115-120 DEG C, and the reaction time is not less than 5 hours; and (3) freeze-drying the aerogel material obtained in the step (2) to obtain a target product. The high-entropy double hydroxide / carbon fiber aerogel electromagnetic wave-absorbing material disclosed by the invention can realize low-frequency absorption of 2.46 GHz under 2 to 8 GHz, and can realize broadband absorption of 12.44 GHz under 2 to 18 GHz.

The invention provides a Fe2. 25Te2 at graphene electromagnetic wave-absorbing material and a preparation method and application thereof.The preparation method comprises the steps that S1, a quartz boat filled with Te blocks is placed on the upstream of a tubular furnace hot area, and the temperature of the hot area is kept at the temperature sufficient to enable Te to be smelted slowly; s2, mixing Fe2O3 powder, fused salt and graphene oxide powder according to a certain mass part ratio, uniformly grinding, thinly paving the mixture in another quartz boat, and placing the quartz boat in the central position of the hot area of the tube furnace; s3, heating the quartz boat in the S1 and the other quartz boat in the S2 at the same time, and carrying out sufficient reaction by using a molten salt assisted chemical vapor deposition technology; and S4, after the reaction in the S3 is completed, naturally cooling to obtain the tetragonal-phase Fe < 2.25 > Te2 (at) graphene broadband electromagnetic wave-absorbing material. The preparation method is simple, convenient and efficient, the product achieves broadband wave absorption through the synergistic effect of the two-dimensional Fe2. 25Te2 nanosheets and graphene, the quality is stable, and performance evaluation is high.

The invention relates to a rare earth composite magnetic material, a rare earth composite magnetic wave-absorbing material and a preparation method thereof. The rare earth composite magnetic material comprises rare earth permanent magnet alloy particles and magnetic metal micro powder which are compounded together, and the surfaces of the rare earth permanent magnet alloy particles are modified with oleic acid. The rare earth composite magnetic wave-absorbing material is obtained by arranging rare earth composite magnetic materials in multiple layers according to an impedance matching principle. According to the method, rare earth permanent magnet alloy blocks are converted into rare earth permanent magnet alloy particles by introducing a ball milling process, electromagnetic parameters of the rare earth permanent magnet alloy particles are optimized, and the rare earth permanent magnet alloy particles are further compounded with magnetic metal micro powder, so that a heterogeneous interface is formed between a rare earth compound and the metal micro powder; impedance matching of the rare earth composite magnetic material is optimized by regulating and controlling the dielectric constant of the rare earth composite magnetic material, electromagnetic parameter regulation and control of the composite wave-absorbing material and effective improvement of the wave-absorbing performance are achieved, and finally the rare earth composite magnetic wave-absorbing material with the broadband absorption characteristic is prepared by optimizing different interlayer matching thicknesses and concentrations.

The invention discloses an intelligent design method and structure of a broadband flexible stealth skin, and relates to the technical field of metamaterials and metasurface wave absorbers.The intelligent design method comprises the steps that unit structures which are the same in size and different in internal structure are designed, and each unit structure comprises a first unit structure and a second unit structure; the first unit structure and the second unit structure respectively realize broadband wave absorption in different frequency band ranges; the reflectivity and the phase of the unit structure are obtained through simulation calculation, and the size of the unit structure is optimized according to the reflectivity and the phase; arraying the two optimized unit structures to obtain a metasurface; and the far-field RCS value of the metasurface is calculated through a far-field formula. Based on the defect that some existing flexible metasurface wave absorbers are too narrow in wave absorbing bandwidth or cannot work at low frequency, the flexible metasurface wave absorber can work at a wide frequency band, and meanwhile, the flexibility can be guaranteed.

The invention discloses a metasurface structure for reducing normal incident scattering of an antenna, and the metasurface structure employs a double-layer design, combines an absorption layer and a frequency selection surface layer, and achieves broadband absorption through a periodically two-dimensional unfolded microstrip patch unit and a three-layer resistor loading metal ring. Ansys electromagnetic field simulation software verifies that the structure effectively reduces the radar cross section of the microstrip antenna within the frequency band of 3-10 GHz, and ensures the normal work of the antenna at the same time. Through deep analysis and simulation optimization, key factors influencing the performance are determined, and the balance between the wave permeability and the wave absorbing property is realized. Besides, an adjustable resistance circuit, a reconfigurable mechanism, an intelligent algorithm and a sensor technology are integrated, the stability and the automation level of the antenna performance are further improved, and an effective solution is provided for improving the scattering reduction effect during forward incidence of radar waves.

The application claims a kind of multiband terahertz absorber based on laminated graphene structure, which is a laminated stack structure.The positive terminal of external power supply is connected to two layers of graphene, and the negative terminal is connected to a gold reflection layer.The Fermi energy level of graphene is controlled by voltage.The structure parameters of each layer, graphene and dielectric layer material characteristics are set.The absorber forms multiple absorption peaks in the 1~5 THz frequency band, with a peak absorption rate of over 90%.At 1.60 THz, a narrowband absorption of 93% is achieved, and at 2.54~4.28 THz, a broadband absorption with a relative bandwidth of 51% is achieved.The normalized equivalent impedance at the resonance frequency point is nearly perfectly matched with the free space impedance.The absorber also has good polarization angle insensitivity, with only slight absorption performance attenuation within an incident angle range of 0~60°.The absorption characteristics can also be adjusted by adjusting the key geometric parameters.The application can simultaneously achieve narrowband and broadband absorption, with excellent absorption performance, and is suitable for interference signal filtering in terahertz communication systems.

This invention relates to a method for preparing a broadband absorption hydrogel. The method comprises the following steps: S1, mixing solvent A (N,N-dimethylformamide or acetonitrile) with deionized water to obtain a mixed solvent; S2, adding polyethylene glycol methyl ether acrylate-480 and acryloylmorpholine to the solvent in S1 and dissolving them to obtain a mixed solution; S3, removing dissolved oxygen from the mixed solution in S2, sealing the container, and stirring under ice bath conditions; S4, adding potassium persulfate and N,N,N',N'-tetramethylethylenediamine to the mixed solution after stirring in S3, and sealing the container again; S5, completing the polymerization reaction in the container at 60 °C to obtain the hydrogel. Compared with the prior art, the hydrogel material provided by this invention has improved reflection loss intensity and effective absorption bandwidth performance, thus providing a new perspective for developing highly flexible and efficient electromagnetic wave absorbers.

The invention discloses a preparation method of a SiC absorbing-transmitting laminated wave-absorbing coating, and belongs to the technical field of electromagnetic wave absorbing materials. The invention aims to solve the problems that the existing wave-absorbing material cannot meet impedance matching and rapid absorption at the same time and cannot meet low-frequency broadband absorption. The method comprises the following steps: 1, mixing cobalt oxide, silicon powder, silicon dioxide powder and carbon powder; 2, calcining and removing carbon at high temperature; 3, preparing a coating I; 4, preparing a coating II; and 5, coating. The method is used for preparing the SiC absorbing-transmitting laminated wave-absorbing coating.

The invention discloses a W-band polarization insensitive wave-absorbing metamaterial structure, which is characterized by comprising a thin film layer, a dielectric layer arranged on the thin film layer and a metal patch pattern layer arranged on the dielectric layer, and two types of metal patches with various sizes are laid on the surface of the metal patch pattern layer. Metal patches in the metal patch pattern layer are rotationally and symmetrically distributed and arranged around the center of the metal patch pattern layer according to a space group, by changing the thickness of the dielectric layer and the sizes of the metal patches, the wave-absorbing metamaterial structure absorbs electromagnetic waves of a specific frequency band and reduces echoes, and the dielectric layer is made of an FR-4 material with the thickness smaller than 0.18 mm; the preparation method has the advantages that the requirements of low cost, light weight, broadband absorption and high flexibility are met.

The invention relates to a preparation method and application of a Ti3C2Tx nano wave-absorbing material with OBO as a surface terminal. The invention belongs to the technical field of wave-absorbing materials. The problem that an existing Ti3C2Tx material is poor in impedance mismatch and electromagnetic wave absorption capacity is solved. The method comprises the following steps: uniformly mixing anhydrous copper chloride, potassium chloride, sodium chloride, anhydrous sodium tetraborate and Ti3AlC2, heating, cooling, grinding, dissolving in an ammonium persulfate solution, stirring, performing ultrasonic treatment, centrifuging and drying. The preparation process is low in cost, simple, green and pollution-free. By changing the surface groups of the Ti3C2Tx material, the dipole polarization is reduced, and the impedance matching is improved. The absorption thickness is 1-2 mm, the effective absorption bandwidth of the wave-absorbing material covers 9-18 GHz, and the broadband absorption target of the material is completed. At the corresponding frequency of 14.24 GHz, when the thickness of the absorbing layer of the wave-absorbing material is 1.36 mm, strong absorption of the wave-absorbing material is realized, and 99.99% of electromagnetic waves can be absorbed.