94 results about "Electromagnetic absorbers" patented technology

In a system including four electromagnetic absorbers for respective four vehicle wheels, motor coils of two respective electromagnetic absorbers disposed corresponding to two diagonally located wheels are connected forming a closed loop including the coils. A generated damping force magnitude can be made different between an instance directions of respective movements of the diagonally located two wheels with respect to the vehicle body are the same, and an instance the directions are opposite each other. Each electromagnetic absorber includes a resistor cooperating with the corresponding coil forming a closed loop, and selectively establishes: a connected state in which one of the four coils and any of the other three coils are connected to form a closed loop; and a non-connected state in which the one of the four coils is not connected to any other coil. An appropriate vibration suppressing action is exhibited with respect to a coupled motion.

A conductive pattern basically has a substantially polygonal outline shape which is a polygon and can have a high peak value of the electromagnetic wave absorption amount as compared to a case when the conductive pattern has a circular outline shape. Thus, the conductive pattern is basically a polygon and at least one corner portion is shaped in curve. This reduces or even minimizes the shift of the frequency at which the absorption amount becomes a peak value by the polarization direction of the electromagnetic wave. Accordingly, in at least one embodiment, it is possible to realize an electromagnetic absorber having an excellent electromagnetic wave absorption characteristic exhibiting a high peak value of the absorption amount of the electromagnetic wave and a small shift of frequency at which the absorption amount becomes a peak value by the polarization direction of the electromagnetic wave.

The invention discloses an electromagnetic wave absorbing material with a periodic structure. The electromagnetic wave absorbing material comprises dielectric blocks formed by a magnetic wave absorbing material grid and a dielectric material, wherein the meshes on the magnetic wave absorbing material grid are through holes, and the dielectric blocks are embedded in the through holes of the magnetic wave absorbing material grid according to a certain periodicity. The preparation method of the electromagnetic wave absorbing material comprises the following steps of: selecting a magnetic wave absorbing raw material, and forming periodically arranged embedding holes on the magnetic wave absorbing raw material to obtain the magnetic wave absorbing material grid; then, selecting a dielectric material of which the relative dielectric constant is in a preset range, cutting the dielectric material into the dielectric blocks corresponding to the embedding holes in shape and size; embedding the prepared dielectric blocks in the embedding holes formed on the magnetic wave absorbing material grid one by one, and connecting together by an adhesive to get the electromagnetic wave absorbing material. The preparation method can effectively expand the operation bandwidth of the wave absorbing material without increase of the thickness, and simultaneously, can obviously reduce the volume density of the magnetic wave absorbing material.

The present invention discloses an absorber of an ultra wide band of a visible and near-infrared band and a preparation method thereof. The absorber consists of a substrate and five layers of optical thin films, the thin film at the lowest layer being a metal absorption layer, a layer of germanium being above the metal absorption layer, other three layers, which have gradually decreased refractive indexes of materials from bottom up, being above the layer of germanium. The absorber, based on the combination of the incidence resistance effect of the metal absorption layer and a wide band anti-reflection film layer of the layer of germanium, establishes an anti-reflection structure of wide band without transmission, is capable of absorbing ultra wide band of visible and near-infrared band, with high efficiency and insensitive incident angles, and is completely beyond a traditional absorber in performance. Compared with traditional absorbers and artificial electromagnetic absorbers provided in recent years, the absorber provided by the invention employs a compact multi-layer thin film structure which is more simple so as to prevent complicated nanofabrication technology, thereby the absorber provided by the invention is reduced in cost of production, is greatly shorten in the production cycle, and is convenient for large-scale manufacture in batches.

An electromagnetic wave absorber for use in the high frequency range above 1 Ghz and a composite member are characterized by the fact that magnetic metal grains are covered with ceramic above 20 volume %. Further, a method of manufacturing the electromagnetic absorber and the composite member is characterized by the fact that composite magnetic particles, in which a plurality of magnetic metal grains and ceramic are unified, are formed through a mechanical alloying method applied to a composite powder composed of magnetic metal powder and ceramic powder. The electromagnetic wave absorber can be used in a semiconductor device, an optical sending module, an optical receiving module, an optical sending and receiving module, an automatic tollgate in which erroneous operation due to electromagnetic wave disturbance is provided by use of the electromagnetic wave absorber.

The invention relates to a porous nickel-carbon nano-composite microsphere electromagnetic wave absorbing material and a preparation method and application thereof. A porous nickel-carbon nano-composite microsphere is a multiphase nano-composite powder body composed of carbon and nickel and a porous-structure monodisperse microsphere with the diameter being 1.2-3.0 microns. The preparing method comprises the steps that nickel acetate, other precursors, polyvinyl alcohol and other surfactant are dissolved in an alcohol solvent and react, and nickelous hydroxide is obtained; after being processed through dehydroxylation, the nickelous hydroxide is mixed with pyrrole, pyridine or acrylonitrile, and then the mixture is directly synthesized into the porous nickel-carbon nano-composite microsphere in a sealed reaction kettle under the condition of 500 DEG C-600 DEG C. The obtained porous nickel-carbon nano-composite microsphere is good in stability and uniformity, has the characteristics of being good in electromagnetic wave absorbility, wide in absorbing and covering frequency range, high in corrosion resistance and oxidation resistance and low in cost and is used for manufacturing electromagnetic absorbers.

The present invention discloses an electromagnetic-wave absorption-material having a periodic structure. The material comprises magnetic-wave absorption-blocks and a dielectric material grid, wherein meshes on the dielectric material grid are through holes, and the magnetic-wave absorption-blocks are embedded in the through holes of the dielectric material grid according to a certain periodicity. The preparation method for the electromagnetic-wave absorption-material comprises the following steps: selecting a magnetic-wave absorption-raw material, and cutting the magnetic-wave absorption-raw material into a desired shape and a desired size to prepare into magnetic-wave absorption-blocks; selecting a dielectric material with a dielectric constant in a preset requirement range, arranging insert holes on the dielectric material in a periodic arrangement manner to obtain a dielectric material grid; and individually embedding the magnetic-wave absorption-blocks into the insert holes arranged on the dielectric material grid, and adopting an adhesive to connect the magnetic-wave absorption-blocks and the dielectric material grid into the integration to obtain the electromagnetic-wave absorption-material having the periodic structure. According to the present invention, the work bandwidth of the wave absorption material can be effectively expanded without increase of the thickness, and the volume density of the magnetic-wave absorption-material can be substantially reduced.

An electromagnetic wave absorber for use in the high frequency range above 1 Ghz and a composite member are characterized by the fact that magnetic metal grains are covered with ceramic above 20 volume %. Further, a method of manufacturing the electromagnetic absorber and the composite member is characterized by the fact that composite magnetic particles, in which a plurality of magnetic metal grains and ceramic are unified, are formed through a mechanical alloying method applied to a composite powder composed of magnetic metal powder and ceramic powder. The electromagnetic wave absorber can be used in a semiconductor device, an optical sending module, an optical receiving module, an optical sending and receiving module, an automatic tollgate in which erroneous operation due to electromagnetic wave disturbance is provided by use of the electromagnetic wave absorber.

The invention belongs to the field of dielectric materials and discloses a flexible polyimide-based composite dielectric film material and a preparation method thereof. The flexible polyimide-based composite dielectric film material is prepared by stirring MXene and polyamic acid formed by dianhydride and diamine at room temperature to obtain a mixed solution of MXene / PAA, coating a base materialwith the mixed solution of MXene / PAA, and amidating at 150-550 DEG C, wherein the MXene is Mn+1Xn, X is selected from C or N, M is selected from Sc, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo AND Mn transition metal elements. The preparation method of the flexible polyimide-based composite dielectric material is simple, the thickness is uniform and controllable, and the dielectric property is good; and as a supercapacitor device or an electromagnetic wave absorbing material, the flexible polyimide-based composite dielectric material has the characteristics of higher electromagnetic absorption efficiency, good cycle stability, small maximum reflection loss, wide absorption frequency range and the like.

The invention provides a method for designing a square ring array based absorber rapidly and efficiently, namely, a square ring array equivalent circuit combined genetic algorithm. The method comprises the steps of: firstly introducing two parameters, namely, resistance loss and equivalent dielectric constant on the basis of an equivalent circuit model of a loss-free square ring array so as to obtain a single / double ring array equivalent circuit model and calculation formula of centrally uploaded lumped resistance; then combining with a transmission line theory to finally elicit an equivalent circuit m of an absorber in a multilayered structure; finally, on the basis of the equivalent circuit, optimizing the performance of the structure by adopting a genetic algorithm to form a complete optimized design process. According to the method, the square ring array based multilayered absorber can be designed, a design goal can be defined based on the practical demand, and a broadband low-profile absorber can be designed freely. With adoption of the method for designing the absorber, short time is taken, the error is small, and the efficiency is high.

The invention relates to a multi-pore hollow iron nano spherical electromagnetic wave absorption material as well as a preparation method and the application thereof. The electromagnetic wave absorption material is a hollow sphere of which the diameter is 500-600nm. The preparation method comprises the following steps: dissolving a precursor salt such as ferric nitrate and surfactants such as polyvinylpyrrolidone into an alcohol solvent, further adding a small amount of deionized water, performing a thermal reaction on the solvent so as to obtain a precursor, performing calcining treatment, further reducing in the presence of a hydrogen atmosphere, and performing direct reduction at 400-500 DEG C, so as to obtain a multi-pore hollow iron nano sphere. The obtained multi-pore hollow iron nano sphere has the characteristics of good stability and uniformity, good electromagnetic wave absorption performance, wide absorption cover frequency range, small corrosion and low cost, and can be adopted to manufacture an electromagnetic absorber.

An electromagnetic absorber assembly (10) capable of minimizing reflectivity caused by reflected and diffracted waves within a test chamber (1) is presented. The absorber assembly (1) includes a plurality of first wedges (11) and a plurality of second wedges (11) disposed in a symmetrical arrangement so as to form a continuous and smoothly changing v-shaped pattern along one or more walls (5-7) of an anechoic test chamber (1). Each wedge (11) has a triangular-shaped first end (26) and second end (27) formed by a pair of side walls (16, 18, or 19) and a base wall (17). One second end (27) of each first wedge (11) contacts and covers one first end (26) of each second wedge (11) along a contact plane (15). First and second wedges (11) are disposed at a first angle (46) and a second angle (47), respectively, about the contact plane (15) in a symmetrical arrangement. The assemblies described could be installed on a flat or shaped absorber base (44) or wall (20) to divert reflected and refracted fields away from a quiet zone (3). Interplay between the shaped absorber base (44) or wall (20) and intersecting wedges (11) facilitates minimization of clutter and secondary scattering.

The invention provides a preparation method for a magnetic graphene nanobelt / graphene composite film. According to the preparation method, ferromagnetic metal nanoparticles wrapped with carbon nano onions grow on the surface of the graphene nanobelt and the surface of the graphene composite film in an in-situ growth manner through a two-step chemical vapor deposition method. The graphene composite film can be transferred to a target matrix without the assistance of a polymer during the transfer process and has the beneficial effects of strong in magnetism, high in optical transparency and high in hole / electron mobility. In addition, the ferromagnetic metal nanoparticles are wrapped with shells of the carbon nano onions so that oxidation, acidification, shedding and the like of the ferromagnetic metal nanoparticles can be avoided, so that the graphene composite film has high strength and good stability. By the adoption of the preparation method, the magnetic graphene composite film can be obtained through macroscopic preparation by the adoption of the two-step chemical vapor deposition method; by the adoption of the method, the technological process is simple, the cost is low, and large-scale production is facilitated; and the method can be widely applied to graphene spintronic devices, electromagnetic wave absorbing materials, flexible graphene film electronic devices and the like.

The invention discloses an rGO / polyimide composite aerogel. The composite aerogel is a three-dimensional conductive network structure formed by interpenetrating rGO of a sheet structure, and polyimideserves as a supporting framework and is located among the sheet structure rGO. The rGO / polyimide composite aerogel is microscopically a two-dimensional lamellar adhesion structure and macroscopicallyhas a porous structure, lamellar structure rGO adheres to each other to provide an effective transmission path for electron transmission, and the porous structure plays a decisive role in light weight and heat resistance of the material; polyimide calcined at a proper temperature endows the composite material with better mechanical properties, so that the bearing capacity and compression resistance of the composite material are effectively improved; due to the introduction of porous rGO, and the electrical conductivity of the composite aerogel is improved, thus facilitating use of the composite aerogel as an electromagnetic wave absorbing material to absorb and attenuate electromagnetic waves.

The invention discloses a terahertz electromagnetic absorber based on metamaterial, and the terahertz electromagnetic absorber comprises a dielectric layer with a square section in the horizontal direction, and an absorption bottom layer is arranged on the bottom surface of the dielectric layer; a patch layer made of indium tin oxide is arranged on the surface of the dielectric layer; the patch layer comprises a square patch arranged in the center of the surface of the dielectric layer, an annular patch concentric with the square patch is arranged on the outer side of the square patch, and a square frame-shaped patch concentric with the annular patch is arranged on the outer side of the annular patch. The terahertz wave absorber has excellent absorption performance on terahertz waves and has the characteristic of wide absorption frequency band.

The invention discloses a metamaterial terahertz electromagnetic absorber. The metamaterial terahertz electromagnetic absorber is characterized by comprising a dielectric layer with a square section in a horizontal direction, a foam layer connected to the bottom surface of the dielectric layer, and a metal grounding layer arranged on the bottom surface of the foam layer; a metal patch layer is arranged on the surface of the dielectric layer; the metal patch layer comprises a regular-cross-shaped patch arranged in the center of the surface of the dielectric layer; square patches are arranged atthe four corners of the regular-cross-shaped patch respectively; a first patch frame and a second patch frame are arranged at the peripheries of the regular-cross-shaped patch and the square patches;and the first patch frame and the second patch frame are two parts which are reserved after two adjacent sides of a square frame are cut by two cuboids respectively. The terahertz wave absorber has excellent terahertz wave absorption capacity, polarization insensitivity and wide-angle characteristic.

The invention provides a preparation method of a magnetic graphene composite film. According to the preparation method, a two-step chemical vapor deposition method is adopted to enable nano ferromagnetic metal particles covered with a carbon nano onion to grow on the surface of a carbon nano tube and graphene composite film. The graphene composite film can be transferred to a target substrate without the assistance of polymer during the transferring process, and has the characteristics of strong magnetism, high optical transparency, high hole / electronic mobility and the like. In addition, the ferromagnetic metal particles are covered by a carbon nano onion outer shell so that oxidization, acidification, falling and the like of the nano ferromagnetic metal particles can be avoided, and the graphene composite film has high strength and good stability. According to the preparation method, the two-step chemical vapor deposition method can be adopted to prepare and obtain the magnetic graphene composite film in macroscopic quantity; the technological process is simple, the cost is low, mass production is facilitated, and the magnetic graphene composite film can be widely applied to graphene spin-electron devices, electromagnetic wave absorption materials, flexible graphene film electronic devices and the like.

The present invention discloses a visible near-infrared ultra-broadband absorber and its preparation method, comprising a substrate and a five-layer optical film, wherein the bottom film is a bottom metal absorbing layer; a top germanium layer is provided on the top of the bottom metal absorbing layer; and remaining three layers are provided on the top of the top germanium layer with gradually decreasing refractive indexes from the bottom to the top. The present invention is based on the blocking effect of the metal absorbing layer and broadband anti-reflection film stack of the germanium layer, which has realized visible near-infrared ultra-broadband absorption with high efficiency and good angle insensitivity, and has fully surpassed traditional absorbers in terms of performances. Compared with conventional broadband absorbers and artificial electromagnetic absorbers proposed in recent years, the compact multilayer film structure in the present invention is simpler and avoides complicated nano-fabrication techniques. Therefore, it can significantly reduce production cost and shorten the production cycle, and is thus suitable for large-scale mass production.

An arrangement including: an electrical subassembly, an optical subassembly, the electrical subassembly and the optical subassembly having an associated electrical connection including at least one electrical lead extending therebetween, and an electrically non-conductive electromagnetic absorber body arranged to at least partly cover the electrical lead.

The invention provides a tire wire automatic welding machine for manufacturing high-performance steel shots. The tire wire automatic welding machine is composed of a rack, a roller motor, a conveying belt, extrusion rollers, a distributor, a distribution brush, an initial positioning mechanism, a chain material plate, a position sensor, a contact mechanism and a control system. A tire wire is arranged on the conveying belt through an electromagnetic absorber, the tire wire is stretched and straightened on the conveying belt through the extrusion rollers and enters the distributor, and even distribution is conducted through the electromagnetic absorber. Multiple grooves are formed in the chain material plate, and multiple wheels are arranged in the grooves. The tire wire enters the grooves and is arranged on the wheels, through re-positioning of the initial positioning mechanism and the position sensor and along with the continuous movement of the tire wire, when the tire wire makes contact with the contact mechanism, butt welding is achieved, along with the continuous movement of the tire wire fater the tire wire is heated, groove openings are perpendicularly downward, the tire wire disengages from the grooves, and automatic feeding, automatic distribution, automatic positioning, welding, and automatic blanking are achieved.

An object of the present invention is to provide a near field electromagnetic absorber that is capable of expressing an effective electromagnetic wave absorption characteristic in a broad range of frequency bands by using conductive material that conductively acts on the electrical field component of an electromagnetic wave. The present invention discloses a near-filed electromagnetic wave absorber consisting essentially of conductive material, wherein the near-field electromagnetic wave absorber absorbs an electromagnetic wave within one wavelength from the electromagnetic wave source by the conductive material, which conductively acts on the electrical field component of the electromagnetic wave.

Disclosed are a paper feed device and an image formation apparatus using the same. The device comprises a drive transmission unit disposed on one end of a rotation shaft, including a clutch gear, a control unit, and a spring; a control unit stopper fixedly disposed on the control unit; and an electromagnetic absorber including a detent. When the detent is located at a brake-off position, the detent and the control unit stopper are separated. When the detent is located at a braking position, the detent makes contact with the control unit stopper, and stops the rotation of the control unit.