54 results about "Electromagnetic absorbers" patented technology

The invention relates to the technical field of electromagnetic materials, and discloses a lossy multimode resonant metasurface unit and a multifunctional active coding wave absorber. The lossy multimode resonant metasurface unit comprises a lossy metal pattern layer, a supporting dielectric layer, an impedance matching dielectric layer and a metal ground layer which are sequentially arranged from top to bottom; the lossy metal pattern layer comprises a multi-mode resonator and a radio frequency PIN diode, the multi-mode resonator is used for realizing a plurality of resonance modes and playing a role in electromagnetic wave frequency selection, and the radio frequency PIN diode is used for playing a role of an adjustable resistor and adjusting the electromagnetic wave loss so as to realize intensity adjustment of reflected electromagnetic waves; every two adjacent multi-mode resonators are connected in a cascading mode through a radio frequency PIN diode and are combined to form a closed-loop pattern. The multifunctional electromagnetic wave absorber is simple in structure, has the constant phase scattering cancellation characteristic, and can independently regulate and control the reflection amplitude so as to solve the technical problem of an existing multifunctional electromagnetic wave absorber.

The invention belongs to the technical field of electromagnetic wave-absorbing materials, and particularly relates to a zero-power absorption type adjustable metasurface composite material and a preparation method thereof. Comprising a panel, a square-ring-shaped metal layer, a cross-shaped metal layer, an electric control metamaterial, a resistive film and a reflecting back plate from top to bottom in sequence, a core layer is arranged among the square metal layer, the cross curve metal layer, the electric control metamaterial, the resistive film and the reflecting back plate; the electric control metamaterial comprises second structure units which are periodically arranged along x and y directions and contain PIN diodes, and the PIN diodes are embedded into the structure; the cross curve metal layer and the square metal layer respectively comprise a third structure unit and a fourth structure unit which are periodically arranged along the x direction and the y direction. Through a cascade structure formed by the electric control metamaterial, the cross-shaped metal layer and the square ring-shaped metal layer, when the PIN diode is switched off, the wave absorbing state is presented, when the PIN diode is switched on, the reflecting state is presented, and electromagnetic waves are absorbed under the condition that bias voltage is not applied.

The invention belongs to the field of electromagnetic wave absorbing materials, and particularly relates to a thin broadband composite wave absorber based on a frequency selective surface. According to the invention, the wave-transparent layer is added in the middle of the multi-layer magnetic material, the mindset of simply stacking the same type of materials in the traditional multi-layer wave-absorbing structure is broken, and the wave-transparent layer is introduced to change the original characteristic that the impedance gradually changes in sequence; meanwhile, a magnetic wave-absorbing material, a frequency selection surface and a medium matching layer are subjected to composite design, the frequency selection surface generates an electromagnetic coupling effect at high frequency, phase and impedance conversion of electromagnetic waves in a multi-layer structure is controlled, and efficient impedance matching and electromagnetic wave energy dissipation in a broadband are achieved through electromagnetic absorption and interference cancellation; and an excellent wave absorbing effect is achieved. The total thickness of the composite wave absorber ranges from 0.064 lambda to 0.1 lambda, the-10 dB absorption bandwidth ranges from 3.3 GHz to 18 GHz, and the relative bandwidth reaches 138%; and meanwhile, the wave absorber has a wide angular domain characteristic under oblique incidence, and a novel thin broadband composite wave absorber scheme is provided.

The invention provides a micron rod-shaped Fe-Si-Al-based composite electromagnetic wave-absorbing material and a preparation method thereof, spherical FeSiAl alloy powder is subjected to ball milling to obtain micron rod-shaped powder, and the surface of the FeSiAl alloy powder is coated with TiO2 by utilizing hydrolysis reaction of tetrabutyl titanate, so that a FeSiAl-coated TiO2 core-shell composite electromagnetic wave-absorbing material is prepared; the FeSiAl-coated TiO2 core-shell composite electromagnetic wave-absorbing material is annealed in an argon or hydrogen-argon mixed gas atmosphere, the micron rod-shaped iron-silicon-aluminum-based composite electromagnetic wave-absorbing material is prepared, the shape anisotropy and the magnetic conductivity of FeSiAl are effectively improved, the oxygen vacancy concentration of TiO2 is regulated and controlled through annealing in a hydrogen-argon mixed gas reducing atmosphere, the polarization relaxation of dipoles is enhanced, and the electromagnetic wave-absorbing effect is improved. The core-shell structure enhances interface polarization, improves magnetic loss and dielectric loss, and effectively enhances the wave-absorbing bandwidth and reflection loss of the wave-absorbing material.

The invention discloses a multifunctional broadband electromagnetic wave-absorbing composite material based on a bionic periodic unit and a multistage core-shell filler and a preparation method thereof.The multistage core-shell filler is used as a raw material, an impregnation technology is adopted, and the bionic periodic unit is impregnated by preparing high-loss paint and impedance matching paint with different concentrations; the electromagnetic wave-absorbing composite material is obtained. Accurate gradient distribution and better impedance matching of electromagnetic parameters in a three-dimensional space are achieved, the density is lower than 6 kg / m under the thickness of 15-20 mm, the plane compression strength is 2 MPa, and the effective absorption bandwidth (RLlt;-10 dB) covers 8-18 GHz. The invention solves the contradiction between the bandwidth, thickness, weight and single function of the traditional wave-absorbing material, and is suitable for the fields of advanced stealth equipment and electromagnetic protection. The material opens up a new direction for the development of electromagnetic wave-absorbing materials, and is expected to be widely applied to many fields such as national defense, communication, electronics and the like.

The invention discloses a Ni3Al-PPy composite wave-absorbing material as well as a preparation method and application thereof, and belongs to the technical field of electromagnetic wave-absorbing materials. The Ni3Al-PPy composite wave-absorbing material with a core-shell structure is successfully synthesized by combining a thermit reaction with a chemical oxidation polymerization method and hydrochloric acid modification. By regulating and controlling the addition amount of the pyrrole monomer in the range of 0.25-0.75 mL, the continuous regulation and control of the thickness of the PPy shell layer from 0.22 [mu] m to 0.31 [mu] m is realized. When the thickness of a PPy shell layer is 0.27 mu m and the matching thickness of the composite wave-absorbing material is 3.0 mm, the minimum reflection loss and absorptivity gt of-40.0 dB are obtained at 9.27 GHz; and when the matching thickness is 2.0 mm, the effective absorption bandwidth reaches 3.02 GHz. According to the invention, the effect of the shell layer thickness in regulating and controlling the performance of the wave-absorbing material with the core-shell structure is illustrated, and a feasible strategy is provided for designing a high-performance light-weight wave-absorbing material with adjustable electromagnetic parameters and enhanced durability.

An assembly and method of use are herein disclosed. The method comprises coupling an antenna and an electromagnetic wave via a passive waveguide having a cross-section dimension, the passive waveguide carrying the electromagnetic wave having a carrier frequency in a range of 500 GHz to 10 THz, the electromagnetic wave having a wavelength, the cross-section dimension of the passive waveguide in a range of at least 4 wavelengths to 50 wavelengths; and positioning an electromagnetic absorber around the antenna.

The invention relates to the field of structural wave absorption, in particular to an electromagnetic wave-absorbing material and a preparation method thereof. The electromagnetic wave-absorbing material comprises: a) a honeycomb substrate having a plurality of honeycomb holes penetrating along the thickness direction; the honeycomb holes are filled with the wave-absorbing medium; wherein the wave-absorbing medium is a condensate formed by cooling after paraffin and an absorbent are uniformly dispersed in a molten state; the absorbent has magnetic loss and / or dielectric loss properties. Impedance is adjusted through paraffin, loss is provided through the absorbent, a propagation path is prolonged through the honeycomb structure, and the electromagnetic wave-absorbing material which is reduced in interface reflection, improved in absorption efficiency, good in structural stability and adjustable in absorption performance is achieved.

This application discloses an electromagnetic absorber and an electromagnetic wave absorption method. The electromagnetic absorber includes: a reflective phase gradient metasurface array, comprising a first dielectric layer, a first metal backplate layer, and multiple metal resonant units. The first dielectric layer is disposed on the upper surface of the first metal backplate layer, and the multiple metal resonant units are arrayed on the first dielectric layer. Each metal resonant unit includes n metal H-shaped structures of different sizes. The reflective phase gradient metasurface array is used to convert plane waves into surface waves. A surface plasmon polariton coupler is used to converge and absorb the energy of the converted surface waves. This application can achieve effective convergence and absorption of surface wave energy.

The present application belongs to the cross technical field of electromagnetic wave absorbing material and radiation cooling material, and specifically provides a cellulose-coated radiation cooling wave absorber and a preparation method thereof, to solve the problem that the existing wave absorber is easy to absorb excessive solar radiation in an outdoor environment, causing device temperature rise and unstable operation. The present application uses PEDOT aerogel as the base body and introduces cellulose aerogel as the surface coating layer. On the one hand, high reflectivity is achieved in the visible light band to reduce solar radiation absorption, and on the other hand, high emissivity is achieved in the near-infrared band to release heat energy and suppress temperature rise, even achieving radiation cooling effect. At the same time, the cellulose aerogel is used as a perfect impedance matching layer to make the incident electromagnetic wave completely enter the material inside, improving the absorption efficiency. Furthermore, the PEDOT and cellulose are compounded to form an upper and lower structure network, so that the incident electromagnetic wave is reflected and scattered multiple times between the layers, prolonging the electromagnetic wave propagation path and further improving the absorption efficiency.

The electromagnetic wave absorber comprises a matching impedance layer, a temperature control phase change resonance layer, a magnetic control phase change regulation and control layer and a metal reflection layer which are sequentially stacked, wherein the temperature-control phase-change resonance layer comprises a base body layer, a plurality of temperature-control phase-change units which are periodically arranged on the base body layer, and a heating layer which is attached to the surface of one side of the base body layer; the heating layer is used for adjusting the temperature of the temperature control phase change unit, so that the conductivity of the temperature control phase change resonance layer is changed; the magnetic control phase change regulation and control layer comprises a magnetic control coil and magnetic control phase change units which are periodically arranged; the magnetic control coil is used for applying magnetic fields with different sizes to the magnetic control phase change unit, so that the magnetic conductivity of the magnetic control phase change material structure is changed; and the arrangement period sizes of the temperature control phase change units and the magnetic control phase change units are between nanometer magnitude and millimeter magnitude. According to the electromagnetic wave absorber, the wave absorbing frequency capable of absorbing waves can be switched and adjusted within a larger range, and therefore the requirements of various different application scenes can be better met.

The invention belongs to the technical field of electromagnetic wave-absorbing materials, and relates to wave-absorbing slurry, polyurethane-based radar wave-absorbing foam as well as a preparation method and application. By adjusting the content ratio of the purified water, the polyurethane resin, the conductive carbon black / acetylene carbon black powder, the silane coupling agent, the anti-adhesion additive and the defoaming agent, the movement of the absorption peak of the polyurethane-based radar wave-absorbing foam between high frequency and low frequency in the frequency range of 2-18 GHz can be adjusted; the optimal average radar reflectivity performance at 2-18 GHz can reach-20 dB, the optimal average radar reflectivity performance at 8-18 GHz can be smaller than or equal to-23 dB, and the optimal radar reflectivity wave-absorbing performance at 13.6 GHz can reach-35 dB. The low-density polyurethane foam is used as a base body, the wave-absorbing slurry is immersed into a grid framework of the base body, the wave-absorbing layer is formed after drying, and meanwhile, the overall weight gain of the sponge is small, so that the polyurethane-based radar wave-absorbing foam achieves the light wave-absorbing effect.

The application relates to the technical field of wave-absorbing materials, in particular to a preparation method of a core-shell structure wave-absorbing agent taking hollow ceramic micropearls as cores. The preparation method of the core-shell structure wave-absorbing agent taking hollow ceramic micropearls as cores has the advantages of low density, simple preparation process, low cost and the like, meets the requirements of light weight and high absorption characteristics, and can be widely applied to the field of electromagnetic wave-absorbing materials.

The present invention provides an absorbing metamaterial, comprising an electromagnetic metasurface material and a first electromagnetic absorbing material and an impedance matching material superimposed on the front and back surfaces of the electromagnetic metasurface material. The electromagnetic metasurface material is a series connection of a capacitor and an inductor in the equivalent circuit of the absorbing metamaterial, and the first electromagnetic absorbing material and the impedance matching material are both resistors in the equivalent circuit of the absorbing metamaterial. One or more metal microstructures are respectively provided in one or more regions of the electromagnetic metasurface material. In addition, the present invention also provides an absorbing structural part and a mobile carrier. The technical solution provided by the present invention can adapt to complex external electromagnetic environments. By combining the electromagnetic metasurface material with a functional absorbing substrate, the present invention changes the absorption frequency of the absorbing functional structure in response to dynamic changes in the electromagnetic interference frequency, thereby effectively improving the electromagnetic compatibility and anti-interference performance in complex electromagnetic environments.

The present application relates to a kind of broadband electromagnetic absorber material processing equipment, belong to material processing technical field.It mainly aims at the electromagnetic shielding product of existing broadband electromagnetic absorber material needs to be cut into finished product after production, to be applied to the problem, the following technical scheme is proposed: including conveying table, the conveying table is fixedly installed with conveyor, the conveyor output end is fixedly installed with power wheel, the conveying table one end is rotatably installed with force wheel, the power wheel is installed with transmission belt between force wheel, laser cutting machine is installed on the conveying table, the conveying table one end is fixedly installed with unwinding frame, two shaft holes are formed in the unwinding frame, and wheel rod is connected to rotating shaft in the shaft hole.The present application sets two groups of coiled material to cut in turn, can be changed when cutting is finished, and the coiled material cut can be conveniently replaced, so that the continuous cutting work can be ensured, and production efficiency is improved.

The invention relates to an antenna design hardware, which both allows antenna designers to realize antenna design in any geometry that they desire and also allows antenna users to build antenna that they desire, and which allows various antenna types to be built by using pieces designed in cell form. Cell is the general name given to the parts in any geometric shape that can form antenna. The invention particularly relates to antenna design hardware which allows for building antenna three-dimensionally and forming antenna design by integrating metal, dielectric, electromagnetic absorber cells and using connectors.

The present invention relates to a flexible, light-transmitting, broadband absorbing structure comprising at least one absorbing shielding layer, encapsulated by a flexible, light-transmitting material. The shielding layer is composed of an array of nested circular rings, whose transmittance can be controlled by adjusting the inner and outer diameters of the rings. The structure is simple, addressing the low visible and infrared transmittance issues associated with electromagnetic absorbers made from opaque conductive materials. Visible and infrared transmittance is adjustable and exceeds 30%, while absorption rates reach over 80%, and the absorption bandwidth is over 10 times the lowest frequency.

The invention relates to the technical field of electromagnetic wave-absorbing materials, in particular to a pointed cone metamaterial composite wave-absorbing structure and a preparation method thereof. The pointed cone metamaterial composite wave-absorbing structure comprises a reflecting layer, a wave-absorbing array pointed cone structure, a wave-transmitting layer and a metamaterial layer. The wave-absorbing array pointed cone structure is divided into a conical cone structure and a wave-absorbing base structure, and the wave-transparent layer is divided into a filling structure layer and a wave-transparent skin. The reflecting layer is arranged below the wave-absorbing base structure, the wave-transparent skin is arranged above the conical cone structure, the filling structure layer is arranged in a gap between the conical cone structure and the wave-transparent skin structure, and the metamaterial layer is located above the wave-transparent skin. The whole wave-absorbing structure is simple, the wave-absorbing performance is adjusted by modifying the periodic array pointed cone structure and the metamaterial structure, and the prepared wave-absorbing structure is thin in thickness, light in mass and excellent in wave-absorbing effect at the low frequency of 0.3-2 GHz.

The invention belongs to the technical field of electromagnetic wave-absorbing materials, and particularly relates to a compatible coating and a preparation method and application thereof. In the use process of the compatible coating prepared by the invention, electromagnetic waves firstly enter through the frequency selective surface layer, a small part of the incident electromagnetic waves continuously enter into the wave absorbing layer through the frequency selective surface layer, the wave absorbing layer absorbs a part of the electromagnetic waves, and the unabsorbed part penetrates through the wave absorbing layer and encounters the metal matrix to be reflected; the electromagnetic waves pass through the wave absorbing layer and the frequency selective surface layer in sequence and are finally received by the radar, the wave absorbing layer absorbs part of the electromagnetic waves again in the reflecting process, the frequency selective surface layer blocks part of the electromagnetic waves, the electromagnetic waves which are absorbed and blocked for multiple times are finally received by the radar, and the stealth capability of the electromagnetic waves can reach-5.5 db; the infrared emissivity of the frequency selective surface layer is between 0.1 and 0.3 when the frequency selective surface layer is 3-5 microns and 8-14 microns, and the infrared emissivity is relatively low, so that radar stealth and infrared stealth can be realized at the same time.

The invention provides a thin-layer strong-absorption mechanical adjustable three-dimensional wave-absorbing structure comprising a bottom plate which is provided with a plurality of basic structure units arranged in a periodic array. Each basic structure unit comprises a hollow frame installed on the bottom plate, a three-dimensional resistive frequency selection substructure arranged on the outer surface of the hollow frame and a nested height-adjustable metal reflection three-dimensional substructure located in the hollow frame and installed on the bottom plate. The invention has the following beneficial effects: through a simple and unique three-dimensional wave-absorbing structure design, the absorption performance with a reflection coefficient lower than-20dB in a range of 8-18GHz is realized, and good oblique incidence stability is achieved; the adjustable reflection coefficient under any incident angle in a broadband range is realized, so that the current requirements of a novel electromagnetic wave-absorbing material which is thin in layer, small in surface density, strong in absorption, adjustable in wave-absorbing performance, simple in structure and good in oblique incidence stability are met.

The application discloses a kind of composite electromagnetic wave-absorbing materials and preparation method thereof.By coating glass, SiO2 and other materials on the outside of graphene, the coating layer has wave-transparent characteristics and can be used to adjust the impedance matching of the composite material, and can also play the role of thermal barrier layer to protect the internal graphene from being oxidized at high temperature.Specifically, a kind of composite electromagnetic wave-absorbing material with special glass / graphene coating structure is prepared by liquid sodium silicate foaming method, thereby relieving the high impedance matching characteristics of reduced graphene oxide itself and improving the electromagnetic absorption performance of the composite electromagnetic wave-absorbing material.Further, by adjusting the heat treatment temperature, the shear stress generated by thermal stress on the graphene sheet is controlled to adjust the particle size of the coating structure, and thus the adjustment of the wave-absorbing performance is realized.The preparation method of the application is simple, green and efficient, and does not have high requirements for related equipment, and a large amount of high-temperature wave-absorbing materials can be prepared in a short time.

The present invention is applicable to the field of electrical installation and provides an intelligent electrical installation device comprising a frame, a load-bearing platform, the load-bearing platform comprising a plate-shaped frame fixedly connected to the frame, a plurality of strip-shaped top blocks evenly distributed along the length of the plate-shaped frame, and elastic telescopic rods connected to the plate-shaped frame mounted on both sides of the bottom of the strip-shaped top blocks; a position adjustment assembly, the position of the position adjustment assembly corresponding to the position and number of the strip-shaped top blocks, the position adjustment assembly comprising an electromagnetic absorber fixedly connected to the plate-shaped frame, and an absorber fixedly connected to the bottom of the strip-shaped top block and corresponding to the position of the electromagnetic absorber. The beneficial effect of the present invention is that the electrical installation work is carried out more smoothly and the efficiency of the electrical installation is significantly improved.

Radar retroreflective (R3) devices including an electromagnetic absorber are provided. The electromagnetic absorber is disposed on selected areas of the device to reduce specular reflection without substantially reducing retroreflection of the device.

The application provides a thin-layer strong-absorption mechanically adjustable three-dimensional wave-absorbing structure, which comprises a bottom plate, a plurality of basic structure units arranged in a periodic array are arranged on the bottom plate, the basic structure unit comprises a hollow frame installed on the bottom plate, a three-dimensional resistive frequency selection substructure arranged on the outer surface of the hollow frame and a nested height-adjustable metal reflection three-dimensional substructure located in the hollow frame and installed on the bottom plate; the application has the following beneficial effects: the application realizes the absorption performance of a reflection coefficient lower than -20 dB in the range of 8-18 GHz through a simple and unique three-dimensional wave-absorbing structure design, and has good oblique incidence stability; further combined with the nested height-adjustable metal reflection three-dimensional substructure, the application realizes the adjustable reflection coefficient in a wide-band range and at any incident angle, thereby meeting the demand for a new type of electromagnetic wave-absorbing material with thin layers, small area density, strong absorption, adjustable wave-absorbing performance, simple structure and good oblique incidence stability.

The utility model provides an intelligent energy-saving high-power automatic absorbing and discharging electromagnetic iron remover, which comprises a metal detector, an electromagnetic absorber, a moving system and a control system, the metal detector and the moving system are sequentially arranged on the same conveying belt front and back, and the electromagnetic absorber is arranged on a moving device; a metal detector is arranged in front of the conveying direction of a conveying belt, when the metal detector detects that materials on the conveying belt are mixed with iron substances, the metal detector sends an action signal to a control system, the control system further controls a moving device to move, the moving device drives an electromagnetic attraction to move to the position above the conveying belt, and the iron substances are conveyed to the conveying belt. And after the iron is attracted, the iron is automatically moved to the outside of the conveying belt within a set time, and the iron is unloaded. As the electromagnetic attractor stops outside the conveying belt during standby at ordinary times, the electromagnetic attractor is electrified to move when iron substances are detected, and the electromagnetic attractor is not electrified when iron substances do not exist, so that the effects of saving energy and prolonging the service life are achieved.

This invention belongs to the field of electromagnetic absorbing materials technology. It relates to a layered high-entropy MBene material, its preparation method, and its applications. This invention utilizes high-temperature Joule heating to prepare the layered high-entropy MBene material. This layered high-entropy MBene material possesses many significant advantages, such as abundant defect density, good conductivity loss, high specific surface area, a large number of exposed surface atoms, and excellent mechanical and electronic properties. It can effectively control electromagnetic parameters and achieve excellent electromagnetic absorption performance. Furthermore, it exhibits nanoscale effects, which can induce lattice distortion, defects, and microstrain, significantly optimizing impedance matching and enhancing dipole polarization and conductivity loss, thus demonstrating outstanding microwave absorption performance. The high-temperature Joule heating synthesis strategy proposed in this invention provides a new approach for the development of advanced high-entropy electromagnetic absorbing materials and offers a general method for the development of other layered materials with tunable structures.

An apparatus for testing electronic devices comprises: a base platform; a cover plate disposed on the base platform, and defining with the base platform an array of test chambers and at least one gap separating the test chambers from each other, wherein the cover plate has at each of the test chambers a top opening for placing an electronic device within the test chamber and a side wall around the opening; an array of test boards each being disposed under one of the array of test chambers, wherein each test board includes a socket connectable with the electronic device placed within the test chamber for testing; and an electromagnetic absorber material disposed within the at least one gap and attached onto the cover plate to absorb electromagnetic interferences between adjacent electronic devices when they are placed within the array of test chambers for testing.

The present invention discloses an LED industrial lamp, which relates to the technical field of industrial lamps and includes a lamp fixture assembly. The lamp fixture assembly includes a lamp base. For this LED industrial lamp, by using a fixed wire to install a loop antenna on the front of the lamp fixture assembly, when the electromagnetic waves generated during the operation of large equipment in the production workshop pass through the loop antenna, an electromotive force will be induced in the antenna. By detecting parameters such as the magnitude and frequency of this electromotive force, it is possible to determine whether there is electromagnetic interference and the intensity and frequency characteristics of the interference. Therefore, by placing the loop antenna near the front of the LED industrial lamp, the electromagnetic interference situation can be detected. Electromagnetic wave absorbing materials are laid inside both the two outer shells and the two side lamp covers. The electromagnetic wave absorbing material is selected as ferrite absorbing material, which can absorb electromagnetic waves within a certain frequency range and convert electromagnetic energy into other forms of energy such as heat energy, thereby reducing electromagnetic reflection and interference inside the lamp.

The present invention belongs to the technical field of electromagnetic wave absorbing materials and discloses a zinc oxide-based electromagnetic wave absorbing material, its preparation method, and application. The zinc oxide-based electromagnetic wave absorbing material has core-shell morphology and rod-like structure characteristics. The core is composed of ZnO and the shell is composed of NiCo2O4, and the NiCo2O4 is in the form of nanosheets. The zinc oxide-based electromagnetic wave absorbing material of the present invention optimizes the microstructure of the obtained sample by regulating the mass ratio of ZnO and metal ions. The resulting core-shell structure product can not only optimize the structure but also improve the impedance matching of the material. The core-shell structure of the zinc oxide-based electromagnetic wave absorbing material increases the heterojunction interface of the material, scattering and reflecting a large amount of incident electromagnetic waves, thereby improving the electromagnetic wave absorbing performance of the material.