127results about How to "Absorbing frequency bandwidth" patented technology

The invention discloses a novel corrosion resistant composite wave absorbing material and a preparation method thereof, and belongs to the field of electromagnetic wave absorbing materials. The wave absorbing material includes 60-100 parts of resin polymer matrix, 50-100 parts of a curing agent, 20-30 parts of ferrite, 20-30 parts of carbonyl iron powder and 5-10 parts of a hollow granular material. The preparation method is as follows: adding a magnetic filler, a conductive filler and a semi conductive filler into resin solution for evenly mixing, and adding the curing agent. The electromagnetic wave absorbing material prepared by the method has the coating thickness of less than or equal to 3mm; in the 2-18GHz, the absorption reflectivity is less than or equal to-10dB; and the electromagnetic wave absorbing material is stealth material with good corrosion resistance, strong wave absorbing performance and wide wave absorbing band.

The invention discloses a flexible electromagnetic wave shielding and absorbing cloth and a production method thereof. The flexible electromagnetic wave shielding and absorbing cloth comprises a four-layer structure which sequentially comprises a chemical fiber fabric layer, an electromagnetic wave shielding layer, an electromagnetic wave absorbing layer and a flame-retardant and waterproof layer from bottom to top. The production method of the flexible electromagnetic wave shielding and absorbing cloth comprises the following steps: 1, drying the chemical fiber fabric; 2, preprocessing the chemical fiber fabric obtained in step 1; 3, plating the chemical fiber fabric obtained in step 2 with a layer of meta; 4, coating the metal layer plated chemical fiber fabric obtained in step 3 with a layer of a wave absorbing coating; and 5, coating the wave absorbing layer coated chemical fiber fabric obtained in step 4 with a layer of a flame-retardant and waterproof coating. The electromagnetic wave shielding and absorbing cloth has the advantages of wide wave absorption frequency band, high absorption intensity, flame retardation and waterproofing property, good flexibility, light weight and thin thickness, and can be applied to electromagnetic interference and electron strike prevention in the fields of electronic products and military devices.

The invention relates to concrete with an electromagnetic wave radiation protection function and a preparation method of the concrete, and belongs to the field of construction materials. The concrete consists of water, dielectric loss type nano-composite wave-absorbing materials, magnetic loss type nano-composite wave-absorbing materials, a wave-absorbing base material, slag powder, cement, coal ash, fine aggregates, macadam and water reducing agents, and is prepared by mixing, stirring and pouring all components step by step. The concrete provided by the invention has high wide frequency wave-absorbing performance in 2-18 GHz, the bandwidth of less than -7dB optimally reaches 14.3 GHz and the bandwidth of less than -10dB reaches 10.6 GHz, and the concrete can be applied to electromagnetic wave of adjacent buildings such as radars, microwave base stations, high-power wireless communication launchers and the like, functional buildings in which a large quantity of precise electronic instruments are placed, critical buildings like national defense and administrative departments. The concrete has high scientific and technological contents, is high in innovativeness and wide in application prospect.

The invention relates to a method for preparing a reduced-oxidized graphene / Fe3O4 / Ag nano composite wave-absorbing material. The method comprises the following steps: preparing GO / Fe3O4 by using a simplified coprecipitation method, and preparing the RGO / Fe3O4 / Ag ternary composite material by employing a wet chemical reducing method. The preparation method is simple and rapid, large-scale production can be realized, the prepared composite material is good in wave-absorbing performance, and different wave bands can be effectively absorbed by adjusting the ratio of RGO to Fe3O4 to Ag, the amount of the reducing agent and the thickness of the composite material.

The invention discloses an alloy micro-powder wave absorbing material and a preparation method thereof. The uniform alloy is prepared by the following steps: taking high purity Fe, Nd and Si as the raw materials, blending the metals according to a certain atom ratio, smelting the metals in an arc smelting furnace to obtain uniform alloy; sealing an alloy sample in a sealed vacuum quartz glass tube, subjecting the quartz glass tube to a heat treatment, quenching, then taking out the sample, primarily and mechanically grinding the sample in a mortar, then transferring the sample to a stainless steel ball-milling tank, carrying out high-energy ball milling under the protection of gasoline, after a while, pouring out the gasoline, taking out the sample powder, and drying the powder in the air to obtain the alloy micro-powder wave absorbing material. The provided iron-based alloy wave absorbing material has the advantages of simple technology, low cost, and wide wave absorbing frequency band.

The invention relates to a preparation method of a chromium-doped ferrous alloy wave-absorbing material. The preparation method comprises the following steps: mixing raw materials: Fe, Nd and Cr according to a certain atom ratio, melting the metals in an arc furnace; then sealing the alloy sample in a vacuum quartz glass tube, then placing the sealed quartz glass tube in a high-temperature environment to carry out a further homogenization treatment, quenching, taking out the alloy sample, mechanically and primarily grinding the alloy sample in a mortar, then transferring the alloy powder to a stainless steel ball-milling tank, carrying out high-energy ball milling under the protection of gasoline, after a while, pouring out the gasoline, taking out the alloy sample powder, drying the powder in the air so as to obtain the alloy micropowder wave-absorbing material.

The invention relates to the technical field of optical protection films, and especially relates to an electromagnetic-radiation-resistant protection film and a preparation method thereof. The preparation method comprises the following steps: step 1, preparing light-cure paint with electromagnetic radiation resistant function; step 2, coating a PET base material with the light-cured paint by using a slight-concave roller, and controlling the coating thickness of the light-cured paint to be 3-10 mu m, the diameter of the slight-concave roller to be 30-50 mm and the line screen of the slight-concave roller to be 40-400; step 3, curing the paint to obtain a film; and step 4, preparing the electromagnetic-radiation-resistant protection film. The electromagnetic-radiation-resistant protection film is good in electromagnetic-radiation-resistant effect, the technology is simple and manure and beneficial for popularization and application. When the electromagnetic-radiation-resistant protection film is used, the electromagnetic-radiation-resistant protection film can be attached to a handset or a display screen by tearing a PET protection film. Compared with electromagnetic-radiation-resistant equipment at home and abroad, such as radiation-proof clothes, electromagnetic-wave protection helmets and the like, the electromagnetic-radiation-resistant protection film is simple and convenient to use and easy to popularize.

The invention relates to the technical field of microwave absorption and particularly relates to a graphene compounded wave absorbing material and a preparation method thereof. The graphene compounded wave absorbing material is prepared through uniformly compounding carbonyl iron and graphene. The preparation method comprises the steps: firstly, preparing graphite oxide by using an improved Hummers method, and then, uniformly dispersing the graphite oxide into a carbonyl iron dispersion solution; then, reducing the graphite oxide to graphene by using an ultrasonic reduction method, thereby preparing the graphene compounded wave absorbing material. Compared with the pure carbonyl iron and the pure graphene, the compounded wave absorbing material provided by the invention has the advantages that the wave absorbing performance is superior, the wave absorbing strength is high, the frequency band of wave absorbing is wide, and the density is relatively low; the compounded wave absorbing material has adjustability, high absorption at different frequencies is achieved through adjusting the mass ratio of the graphene to the carbonyl iron and the thickness of the compounded material.

The invention provides an alloy microwave absorbing material added with vanadium and a preparation method. The preparation method comprises the following steps: taking proper amounts of metal Fe, Nd and V of which the purities are higher than 99.5% respectively for dosage according to the atomic ratio of Fe17Nd2-xVx, wherein X is more than or equal to 0.1 and is less than or equal to 0.8; smelting into an alloy ingot by using a vacuum electric-arc furnace; performing vacuum sealing by using a quartz glass tube; inspecting the airtightness by soaking the glass tube in water; performing operations such as homogenization, quenching and mechanical preliminary pulverization; pouring the sample into a ball-milling jar, and performing ball-milling by using a planetary ball mill under the gasoline environment protection condition; pouring out the gasoline after the ball-milling is finished; taking out sample powder and drying, thus obtaining an alloy micro powder wave absorbing material.

The invention relates to the technical field of microwave absorption, in particular to a graphene-based ternary composite wave-absorbing material and a preparation method thereof. The preparation method comprises the steps of firstly, preparing silicon dioxide-coated carbonyl iron core-shell composite particles by using a sol-gel method, then preparing graphite oxide by using an improved Hummers method, evenly dispersing the graphite oxide into dispersion liquid of the silicon dioxide-coated carbonyl iron core-shell composite particles, and finally, using an ultrasonic reduction method to enable graphite oxide to be reduced into graphene so as to prepare the graphene-based ternary composite wave-absorbing material. The preparation method provided by the invention is simple and efficient; the prepared composite wave-absorbing material is more excellent in wave absorbing performance, high in wave absorbing strength, wide in wave absorbing bandwidth and smaller in density compared with a pure carbonyl iron binary composite wave-absorbing material and a pure graphene and carbonyl iron or graphene binary composite wave-absorbing material; the graphene-based ternary composite wave-absorbing material also has regulation performance, and can realize strong wave absorption under different frequencies by adjusting the thickness of a coating layer SiO2, the mass ratio of graphene to the coated core-shell composite particles and the thickness of the ternary composite material.

The invention relates to a broadband silicon carbide high temperature resistant wave-absorbing coating and a preparation method thereof, and mainly overcomes the problems of poor high temperature performance and complex process of conventional wave-absorbing coatings. The wave-absorbing coating takes silicon carbide micro powder as a main wave-absorbing agent; and wave-absorbing band is adjusted by controlling the proportions of silicon carbide in different morphologies. The preparation method comprises the steps of (1) preparation of a coating material: weighing the silicon carbide micro powder, oxide, a silicate binder, a surfactant and deionized water according to amounts, mixing the above raw materials and ball milling for 4 h to obtain the wave-absorbing coating material; (2) preparation of the coating: subjecting an alloy as a substrate to sand blasting treatment, then spraying a transition layer containing NiCr AlY on the substrate by a hot spraying method, spraying the prepared wave-absorbing coating material on the transition layer, drying the coating at a normal temperature, putting the coating into an oven for drying after the surface of the coating is dried, a drying temperature being 50-180 DEG C, subjecting the dried coating to heat treatment for 1-12 h at a temperature of 600-1,200 DEG C, and cooling the coating along with the oven to obtain the high temperature resistant wave-absorbing coating. The wave-absorbing band of the prepared wave-absorbing coating is mainly between 2 GHz and 20 GHz.

The invention provides a protein-based carbon / magnetic Fe Co nanoparticle composite wave-absorbing agent and a preparation method and application thereof, and belongs to the technical field of wave-absorbing materials. The preparation method of the protein-based carbon / magnetic Fe Co nanoparticle composite wave-absorbing agent comprises the following steps: 1) mixing water, ferric chloride hexahydrate, ferrous chloride tetrahydrate and cobalt chloride hexahydrate, and reacting for 1-2 h at the temperature of 70-100 DEG C to prepare magnetic nanoparticles; 2) mixing the magnetic nanoparticles with egg white liquid, and curing to obtain a protein-magnetic nanoparticle compound; 3) carbonizing the protein-magnetic nanoparticle compound obtained in the step 2) to obtain the protein-based carbon / magnetic Fe Co nanoparticle composite wave-absorbing agent. The material prepared by using the composite wave-absorbing agent has strong wave-absorbing performance, meanwhile has the characteristicsof wide wave-absorbing frequency band, small matching thickness of an absorber and the like, and has a large application prospect in the field of wave-absorbing materials.

The present invention provides a material with characteristics of fire retardation, thermal insulation and wave absorption. The material comprises a base layer, wherein the base layer is mesh fabric, both sides of the mesh fabric are coated with an adhesive coating layer, and the adhesive coating layer is a polyvinylchloride adhesive coating layer. The adhesive coating layer comprises a wave absorption agent, wherein the wave absorption agent comprises nickel-plated glass beads, and a mass ratio of the wave absorption agent powder to the adhesive is 0.17-1.85:1. The present invention further provides a preparation method for the material. According to the material with characteristics of fire retardation, thermal insulation and wave absorption in the present invention, the polyvinylchloride adhesive is added with the wave absorption agent, such that functions of fire retardation, thermal insulation and wave absorption can be concurrently provided; the material of the present invention can concurrently has functions of fire retardation and thermal insulation, and characteristics of high wave absorption strength, wide wave absorption frequency band, and small surface density; and the material of the present invention can be used for wave absorption defilading, electromagnetic shielding, and the like.

The invention discloses a nanometer composite wave absorbing powder having a low density and a porous structure, and its preparation method. The preparation method of the composite wave absorbing powder comprises the following steps: 1, preparing porous ferrite through adopting a citrate sol-gel method, adding an organic additive in the porous ferrite preparation process, burning at a high temperature for combusting the organic additive to form ferrite having a porous structure; and 2, preparing an oxide doped precursor through adopting a sol-gel method, adding the ferrite having a porous structure, and burning at a high temperature to obtain the composite wave absorbing powder. The method reduces the density of the composite wave absorbing powder, the powder having a porous structure has a certain heat insulation effect, and the composite wave absorbing powder prepared through the method has the advantages of compatible absorption of radar waves and infrared waves, low density, wide absorption wave frequency band, good wave absorption performance, and simple preparation process, and overcomes the large density disadvantage of wave absorption materials prepared through using traditional ferrite.

The invention relates to the technical field of marine power, in particular to a magnetorheological elastomer thrust bearing base dynamic vibration absorber and a use method. The dynamic vibration absorber is arranged on a thrust bearing base and comprises magnet yoke sets, a magnetism isolating support shaft, a magnetic conductive shaft sleeve, magnetorheological elastomers and an electromagnetic assembly. The outer layer of the magnetism isolating support shaft is sleeved with the magnetic conductive shaft sleeve. The two ends of the magnetic conductive shaft sleeve are provided with the parallelly arranged magnet yoke sets correspondingly. The joints of the magnetic conductive shaft sleeve and the magnet yoke sets are provided with the magnetorheological elastomers. At least one electromagnetic assembly is arranged around the part, between the two magnet yoke sets, of the magnetic conductive shaft sleeve. According to the magnetorheological elastomer thrust bearing base dynamic vibration absorber and the use method, longitudinal vibration of the thrust bearing base is controlled effectively, then the transmitting ratio of pulsating force of a propeller through the bearing base to a boat body is lowered, and the purpose of reducing of radiation noise is achieved.

The invention provides a method for preparing a reduced graphene oxide / CoFe2O4 / Ag composite wave-absorbing material. According to the method, RGO / CoFe2O4 is prepared by use of a hydrothermal method, and then the RGO / CoFe2O4 / Ag ternary composite wave-absorbing material is prepared by use of a wet chemical method. The method is characterized in that no any surfactant is needed and also no insert gas such as nitrogen is needed for protection; the preparation process is simple and the preparation conditions are easy to implement.

The embodiment of the invention relates to a wave absorbing device with an adjustable frequency. The wave absorbing device with an adjustable frequency comprises a reactance adjustable varactor with a wave absorbing metamaterial, and a master control unit for adjusting the varactor, wherein the varactor is arranged on each metamaterial unit. The wave absorbing device provided by the invention can control the varactor arranged on each metamaterial unit through the master control unit to further adjust the equivalent electromagnetic parameters of each metamaterial unit, so that the wave absorbing material meets the impedance matching characteristics and attenuation matching characteristics for incident electromagnetic waves with different frequencies. And the wave absorbing device has a wider wave absorbing frequency band and a higher wave absorbing efficiency.

The invention discloses a processing method of a wideband electromagnetic wave absorption suede fabric. The processing method comprises the following steps: weaving a dual-layer fabric by selecting and using conductive fiber blended yarns; diluting and uniformly mixing a wave absorbent with a flexible adhesive to prepare a wave absorption adhesive with good adhesion performance; soaking plush of a prepared one-sided suede fabric in the prepared wave absorption adhesive; performing pad-roll on the obtained suede fabric by a proper pressure and removing the excess wave absorption adhesive by extruding; baking the obtained suede fabric in a baking oven to prepare the special wideband electromagnetic wave absorption suede fabric. The wideband electromagnetic wave absorption suede fabric has the absorbed electromagnetic wave frequency range of 300 MHz to 40 GHz, can serve as an important biological health protection or facility safety protection product, and radically eliminates the harm caused by electromagnetic radiation.

The invention provides a rice husk based C / magnetic Co particle composite wave absorber and a preparation method thereof and belongs to the technical field of wave absorbing materials. Magnetic Co particles of the rice husk based C / magnetic Co particle composite wave absorber are 1.3 mu m in size, and rice husk based C also has a porous structure. The preparation method of the composite wave absorber comprises three steps: pretreatment: rice husk is washed with purified water and treated with HF (hydrofluoric acid), Si compounds in the rice husk are removed through etching, and the rice husk treated with the HF is obtained after drying; modification: the rice husk treated with the HF is soaked in a CoCl2 aqueous solution, water is removed through reduced-pressure distillation, and CoCl2 modified rice husk is obtained; carbonization: the CoCl2 modified rice husk is placed in a tube furnace and carbonized at a high temperature in an inert gas atmosphere, the carbonized material is further ground, and the rice husk based C / magnetic Co particle composite wave absorber is obtained. The prepared wave absorber has excellent wave absorbing performance and shows stronger absorbing characteristic on electromagnetic waves.

The invention discloses a low-temperature plasma generating device with a stealth function, comprising discharging patches, an electromagnetic transparent dielectric coating, a micropore, a carbon fiber discharge electrode and a metal conducting layer. A low-temperature plasma generating method with a stealth function, the discharging patches are uniformly installed on the outer surface of military equipment, and the discharging patches are connected with a high-voltage power supply; the high-voltage power supply is controlled to release pulse high voltage, the pulse voltage is connected witha carbon fiber discharge electrode, dielectric barrier discharge is carried out under the action of the electromagnetic transparent dielectric coating to release the plasma, and a plasma cloud clusteris formed. According to the device in the invention, the high-frequency high-voltage plasma generator is used for manufacturing the plasma, that is, under a high-frequency voltage condition, a dielectric barrier discharge mode is used to avalanche the air into plasma, and radar signals can be shielded.

The invention discloses a carbon coated nickel nanoparticle and silicon resin composite microwave absorbing coating and a preparation method thereof. The composite microwave absorbing coating is composed of 40%-60% by weight of carbon coated nickel nanoparticles and silicon resin. The preparation method comprises the steps that the carbon coated nickel nanoparticles are prepared through an arc discharge method; the carbon coated nickel nanoparticles are filled into the silicon resin to be evenly mixed, and coating slurry is obtained; an adequate amount of xylene is taken to serve as solvent to be added into the slurry, and the viscosity of the slurry is adjusted; a curing agent is added into the slurry, even stirring is conducted, and the coating with certain thickness is prepared. The composite microwave absorbing coating prepared through the method has the advantages of being wide in wave-absorbing band, good in wave-absorbing efficiency, low in reflectivity, high in stability, good in mechanical property and the like, the technology is simple, and the coating is easy to repair.

The invention discloses a broadband wave-absorbing material based on 3D printing. The material is formed by sequentially stacking a dielectric layer and a reflecting layer from outside to inside, and has a periodic three-dimensional structure. The dielectric layer is composed of an organic resin binder, ceramic powder and a wave-absorbing agent, the dielectric layer is of a three-dimensional periodic array structure, structural units are cylinders, cuboids, prisms or prismatic tables, the number of layers is 2-3, and the structural units are coaxially stacked from small to large from outside to inside, and the reflecting layer is made of metal, ceramic or a high-molecular compound. The preparation method of the broadband wave-absorbing material comprises the following steps: establishing a model, preparing powder, and preparing the material through 3D printing. According to the novel three-dimensional structure metamaterial, the integral structural strength of the wave-absorbing material is effectively improved, the adjustability of the wave-absorbing performance of the material is greatly improved, the wave-absorbing frequency band is widened, meanwhile, the manufacturing process is simple, the production efficiency is high, and batch production can be achieved easily.

The invention relates to a method for preparing a reduced-oxidized graphene / Cu2O / Cu quantum dot ternary wave-absorbing material. By taking sodium borohydride as a reducing agent, the RGO / Cu2O / Cu ternary composite wave-absorbing material is prepared by employing a simple wet chemistry method. The Cu2O and Cu have the size of less than 5nm and are directly loaded on an RGO nanosheet. The preparation method is simple and rapid, the compounding process is short in time consumption (only 4-6 hours), the preparation process is simple, the preparation conditions are easily realized, and large-scale production can be realized, and moreover, the large-scale production can be realized, the prepared composite material is good in wave-absorbing performance, and different wave bands can be effectively absorbed by adjusting the addition ratio of the GO and Cu<2+> and the thickness of the composite material.

According to the invention, Nd and La are added into a Fe base alloy to prepare microwave absorption micropowder with excellent performance, and the micropowder is characterized in that metal Fe, Nd and La are used as raw materials, burdening is performed according to an atom ratio of Fe17Nd2-xMnx (x is larger than or equal to 0.2 and is smaller than or equal to 0.7), operations of smelting, vacuum sealing, homogenization treatment, quenching and the like are performed to prepare the wave absorption alloy, then the alloy is mechanically preliminarily crushed, and is ball-ground with a planet type ball grinder under a gasoline environment protection condition, after ball grinding, the powder is collected and aired to obtain the wave absorption micropowder.

The invention relates to a multi-stable nonlinear energy well with a piecewise linear beam and permanent magnet negative stiffness. The multi-stable nonlinear energy well comprises the piecewise linear beam which is composed of three piecewise linear rods with different stiffness. One end of the piecewise linear beam is fixed to a piecewise linear beam pedestal, and the other end of the piecewiselinear beam is inserted into an MNES mass block. During installation, a certain pre-compression amount is reserved between the piecewise linear rods of the two sides and the MNES mass block. A gap isreserved between the piecewise linear rod in the middle and the MNES mass block. Along with up-and-down movement of the MNES mass block, the compression amount between the MNES mass block and the piecewise linear beam is changed, and piecewise linear positive stiffness is produced. The required negative stiffness is produced through inner magnets and outer magnets, and required multiple stable positions are constructed through the optimal cooperation of the positive stiffness and negative stiffness. Vibration energy of a to-be-damped system is transmitted into the energy well in a unidirectional mode, and finally the energy is rapidly dissipated through damping by the energy well, and thus main system vibrations can be efficiently restrained. The energy well is simple in structure, wide invibration suppressing frequency band and remarkable in vibration suppressing effect.

The invention provides a preparation method of a Fe-Nd-Al alloy microwave absorbing material. The preparation method comprises the following steps: preparing high-purity metals: Fe, Nd, and Al according to a certain atom ratio, adding the prepared Fe, Nd, and Al into an arc melting furnace to smelt the alloy, transferring the alloy to a quartz glass tube, vacuumizing and sealing the quartz glass tube, homogenizing and quenching the alloy, primarily and mechanically grinding the alloy in a grinding mortar, finally carrying out high-energy ball milling under the protection of gasoline, taking out the sample powder, and drying in the air so as to obtain the microwave absorbing material having the advantages of wide absorption frequency band, high absorption rate, and light weight.

The invention belongs to the technical field of wave-absorbing materials and discloses a resin column reinforced broadband wave-absorbing / bearing composite material and a preparation method thereof. The preparation method comprises the steps of sequentially stacking an impedance matching layer playing a role in impedance gradual change, a wave-absorbing layer containing an absorbent and a reflecting layer are on a lower portion of a wave-transmitting layer to form a laminated structure, and punching through holes in the formed laminated structure, enabling resin to flow into the through holesby adopting a wet forming process, and forming resin column structures penetrating through the whole laminated structure at the positions of the through holes. According to the invention, the throughholes are punched in advance in the thickness direction of a multi-layer structure prefabricated body, the process characteristics of wet molding of the composite material are used, the resin is poured into the through holes in the prefabricated body filling process to form Z-direction resin column structures, the effect of enhancing the interlayer performance is achieved, the forming process is simple, the mechanical property is excellent, the interlayer performance is greatly enhanced through the resin column structures formed at the through holes, and the defect that a current wave-absorbing composite material wave-absorbing layer is easily layered can be effectively overcome.

The invention discloses a preparation method of a graphene composite wave absorbing material based on 5G communication and application of the graphene composite wave absorbing material. According to the preparation method disclosed by the invention, a flake graphene composite wave absorbing material with an excellent impedance matching property is obtained by a mixture of mechanical ball-milling carbonyl iron powder and graphene oxide. In the 2 to 18GHz frequency range, when the coating thickness is 1mm, a reflection loss peak value of the graphene composite wave absorbing material reaches -5.8dB near 5GHz, and the effective frequency width of absorption in which RL is smaller than -4.0dB reaches 5GHz (3.2 to 8.2GHz) fully covers the future China Mobile 5G full-band (3.3 to 3.6GHz and 4.8to 5.0GHz) released by the Ministry of Industry and Information Technology. In addition, the position of an absorption peak of the graphene composite wave absorbing material can be changed by adjusting the ball-milling time and the content of calcium stearate, so that the aim of selectively absorbing interference noises in any two frequency bands in the future 5G is achieved.

The invention provides a semi-active / full-active integrated type electromagnetic vibration absorber which comprises spring steel sheets, two rotors, two stators, an aluminum plate and a base. The upper end portions and the lower end portions of the two spring steel sheets are respectively fixed together to form a spring outer shell, wherein the two sides of the spring outer shell are arc in shape, and the middle of the spring outer shell is a line segment. The upper end portions of the two spring steel sheets are fixed together through an upper bottom plate, and the lower end portions of the two spring steel sheets are fixed together through a lower bottom plate. The aluminum plate and the upper bottom plate are fixed through an angle aluminum piece, the lower end of the aluminum plate and a guide shaft are fixed, the guide shaft is inserted into a linear bearing, and the linear bearing is fixed in a base. The two rotors are reversely fixed to the aluminum plate and located on the two sides of the aluminum plate respectively, the portions, on the two sides of the guide shaft, of the base are respectively provided with a stud, the two stators are arranged on the two studs respectively, the two stators and the two rotors are arranged in an opposite mode, exciting coils are wound on the rotors, and magnet exciting coils are wound on the stators. According to the semi-active / full-active integrated type electromagnetic vibration absorber, switching of semi-active operation and full-active operation can be achieved.

The invention relates to a preparation method of a metal doped carbon nanotube / polyvinyl chloride composite wave-absorbing film material. The method is characterized in that the method comprises the following steps: preprocessing carbon nanotubes by using a mixed acid, mixing a certain amount of lanthanum nitrate and the carbon nanotubes in an aqueous solution, carrying out ultrasonic treatment at a certain temperature for 1h, drying, and grinding to obtain a material for later use; and sequentially adding a certain amount of lanthanum nitrate doped carbon nanotubes, a plasticizer, a cross-linking agent and the like to a tetrahydrofuran solution of polyvinyl chloride, carrying out ultrasonic treatment, magnetically stirring for uniform mixing, injecting the obtained colloidal solution to a die, and drying at room temperature for 24h to obtain the rare earth doped carbon nanotube / polyvinyl chloride composite wave-absorbing film material. The preparation method of a composite wave-absorbing film is economic and suitable, and is simple to operate. The rare earth doping enhances the electromagnetic wave absorbing performance of multiwall carbon nanotubes in a 2-18GHz range.