42results about How to "Broaden the absorbing bandwidth" patented technology

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 invention discloses a carbonyl iron/graphene/polyvinylpyrrolidone compound wave-absorbing material, a preparation method thereof and the prepared wave-absorbing plate prepared by the method. The carbonyl iron/graphene/polyvinylpyrrolidone compound wave-absorbing material comprises a carbonyl iron powder core layer, a reduction-oxidation graphene layer which is coated on the periphery of the carbonyl iron powder core layer and a polyvinylpyrrolidone layer which is coated on the periphery of the reduction-oxidation graphene layer. The carbonyl iron/graphene/polyvinylpyrrolidone compound wave-absorbing material disclosed by the invention is characterized by simple preparation process, strong electromagnetic wave absorption capacity, wide frequency bandwidth, low cost and important application value in the fields of microwave absorption, electromagnetic leakage solution, electromagnetic shielding, and the like.

The invention discloses a zirconium and titanium-co-doped barium ferrite wave-absorbing powder material. The chemical formula is BaFe(12-x)ZrxTixO19, wherein x is equal to 0.2-0.4. The zirconium and titanium-co-doped barium ferrite is single-phase polycrystalline powder, and Fe<3+> and Fe<2+> exist in the barium ferrite at the same time. A preparation method comprises the following step of preparing the zirconium and titanium-co-doped barium ferrite wave-absorbing powder material by virtue of a self-propagating combustion method which is combined with ball-milling and a sequential secondary vacuum high-temperature thermal treatment process. The wave-absorbing material disclosed by the invention has the characteristics of being strong in absorption loss, wide in wave absorbing bandwidth, thin in match thickness and wide in modulated wave-absorbing frequency range. The effective wave absorbing bandwidth is controlled in a frequency range of 18-40GHz, double absorption peaks appear, the maximum absorbing bandwidth can reach 16GHz, the optimum match thickness is just about 1mm, and the optimum reflection loss RL value at the special frequency can reach about -48dB. The barium ferrite wave-absorbing powder material is simple in preparation process, can be used for a wave-absorbing coating, and can be widely applied to the fields of electromagnetic shielding and stealth.

The invention discloses a dielectric-based broadband tunable metamaterial wave-absorbing body and relates to the field of wave-absorbing materials and metamaterials. An electromagnetic wave-absorbingunit is formed by combining a soil material with a dielectric substrate on which a conductive thin film is pasted; and impedance matching is achieved through the electromagnetic wave-absorbing unit and a free space to achieve a relatively good wave-absorbing effect. The metamaterial wave-absorbing body is formed by periodically arranged wave-absorbing units and comprises the dielectric substrate,the soil material and the conductive thin film clung to the dielectric substrate. Square holes which are circular in inside are firstly engraved into the dielectric substrate, and then the soil material is embedded into the holes of the dielectric substrate and is in contact with the conductive thin film. By using the characteristic that the soil material has a high dielectric loss along with thechange of the water content in a microwave frequency band, the wave-absorbing bandwidth can be significantly increased under the condition of a relatively small thickness; main raw materials are easyto obtain and the metamaterial wave-absorbing body is eco-friendly, simple in structure, mature in preparation process, low in cost and suitable for large-scale production; and the wave-absorbing effect of the metamaterial wave-absorbing body can be adjusted through changing the water content of the soil material, so that operation is more convenient and concise.

The invention relates to a wave-absorbing metamaterial comprising a plurality of metamaterial sheet layers. Each metamaterial sheet layer comprises a base material and a plurality of artificial microstructural groups which are attached to the base material and arranged in an array. Each of the artificial microstructural groups and the portion, occupied by each artificial microstructural group, of the base material are defined as a metamaterial unit. The artificial microstructural group on each metamaterial unit comprises more than one kind of artificial microstructural element. By means of the coupling of the various kinds of the artificial microstructural element of the multiple layers of artificial microstructural groups, the electromagnetic waves within a wide frequency range can be not reflected as much as possible and enter the inside of the wave-absorbing metamaterial to the maximum extent. In addition, high losses are produced by means of the resonance of the wave-absorbing metamaterial, so that the incoming electromagnetic waves can be attenuated rapidly in large amounts and transformed into heat energy or other energy and the wave-absorbing bandwidth of the wave-absorbing metamaterial is improved.

The present invention discloses a segmented wave-absorbing honeycomb sandwich composite material with a corrugated structure, which is formed by a wave-absorbing honeycomb and matching panels arrangedon upper and lower sides of the wave-absorbing honeycomb. The wave-absorbing honeycomb is made of a honeycomb core material segmentally impregnated with a wave-absorbing adhesive solution; an impregnated layer of the wall of the wave-absorbing honeycomb is of a corrugated structure; the matching panels on the upper and lower sides are glass steel plates; and the wave-absorbing honeycomb sandwichcomposite material is of a sandwich structure, with the wave-absorbing honeycomb and the matching panels being bonded with a prepreg which is molded by an autoclave process. The present invention provides a segmented wave-absorbing honeycomb sandwich composite material with a corrugated structure and a preparation method thereof, wherein a honeycomb core material is segmentally impregnated at thetop and the bottom with a prepared wave-absorbing adhesive solution and a corrugated structure is prepared by using a self-designed mold, so that the prepared wave-absorbing honeycomb sandwich composite material has the characteristics of light weight, small thickness, wide absorption band, high bearing capacity and the like.

The invention belongs to the technical field of electromagnetic noise absorption, and discloses a heat-conductive electromagnetic noise suppression sheet and a preparation method thereof, the heat-conductive electromagnetic noise suppression sheet comprises an organic silicon resin-based wave-absorbing medium top layer, an organic silicon resin-based wave-absorbing medium bottom layer, and an electromagnetic band gap structure layer embedded between the organic silicon resin-based wave-absorbing medium top layer and the organic silicon resin-based wave-absorbing medium bottom layer; each organic silicon resin-based wave-absorbing medium layer is an organic silicon resin and electromagnetic wave absorber composite; the electromagnetic band gap structure layer comprises a plurality of metalfoil grids and a wave-absorbing medium layer, the metal foil grids are uniformly distributed and fixed on the wave-absorbing medium layer; a heat conduction network is constructed in an organic silicon resin-based wave-absorbing medium by use of an electromagnetic band gap structure, by use of electromagnetic wave regulation characteristics, wave absorbing ability is enhanced, the thermal conductivity and the electromagnetic noise suppression capability of the heat-conductive electromagnetic noise suppression sheet can be significantly improved, and the wave-absorbing bandwidth and the centerfrequency loss intensity are significantly improved compared with the existing heat-conductive electromagnetic noise suppression sheet.

The invention provides a composite wave-absorbing material with rare earth element-doped magnetic particles loaded on layered MXene. The composite wave-absorbing material is prepared from a rare earth element-containing compound, a magnetic element-containing compound and an MAX phase. The composite wave-absorbing material is endowed with a wider wave-absorbing frequency band and more excellent wave-absorbing performance through doping of the rare earth element. Meanwhile, due to the introduction of rare earth element, the composite wave-absorbing material has relatively low density. The preparation method of the composite wave-absorbing material is simple, the preparation process is safe and free of toxic and harmful substances, and the composite wave-absorbing material has wide application prospects.

The invention provides a low-temperature curing high-temperature-resistant wave-absorbing coating and a preparation method thereof, and relates to the field of radar wave-absorbing functional coatings. The high-temperature-resistant wave-absorbing coating is prepared by taking methyl phenyl organic silicon resin or modified methyl phenyl organic silicon resin as an adhesive, alloy powder subjected to ball milling treatment as an absorbent and silicon-nitrogen oligomer as a curing agent, and adding a solvent, an auxiliary agent, a toughening agent and the like. The wave-absorbing coating has relatively high temperature tolerance, can resist 400 DEG C for 100 hours, can be cured at the temperature less than 80 DEG C, has relatively small reflectivity change before and after high temperature, has relatively high adhesive force and flexibility, and can solve the problems of low high temperature resistance, short temperature resistance time, high curing temperature, poor mechanical property and high coating hardness after curing of the existing wave-absorbing coating.

The invention discloses a novel wave-absorbing function design with material and structure wave-absorbing functions being integrated. A thick film characteristic of SU-8 novel negative photoresist is utilized; wave-absorbing materials and the SU-8 photoresist are combined, and micro-electronic technique means is utilized to perform patterning and a periodic structure is formed; and then the area outside the developed photoresist structure is filled with wave-absorbing materials based on wave-absorbing characteristic demands, and thus the wave-absorbing functions of the double materials and double structures are expressed. The thick film characteristic of the SU-8 photoresist is utilized and a patterning method is utilized to give play to the double wave-absorbing function of the materials and the structure; the novel wave-absorbing function design has the technical features of wide structure variable range and large material selection freedom; and the novel wave-absorbing function design facilitates the optimization design of a wave-absorbing system, and helps to improve wave-absorbing bandwidth and efficiency.

The invention relates to the field of high-temperature-resistant wave-absorbing materials, and particularly discloses an elevator degree distribution silicon carbide fiber reinforced ceramic-based ultra-wideband wave-absorbing composite material. The composite material, starting from the incident direction of the electromagnetic wave, sequentially comprises a first high-resistance silicon carbide fiber reinforced ceramic matrix composite material layer, a first lossy silicon carbide fiber array reinforced ceramic matrix composite material layer, a second high-resistance silicon carbide fiber reinforced ceramic matrix composite material layer, a second lossy silicon carbide fiber array reinforced ceramic matrix composite material layer, a third high-resistance silicon carbide fiber reinforced ceramic matrix composite material layer, a third lossy silicon carbide fiber array reinforced ceramic matrix composite material layer and a fourth high-resistance silicon carbide fiber reinforced ceramic matrix composite material layer; and the lossy silicon carbide fiber array is composed of two-dimensional fiber cloth patch units arranged in a periodic array mode, the periodic units are the same in size, the patch sizes are sequentially increased, and the sheet resistance is sequentially reduced. The wave-absorbing bandwidth of the wave-absorbing composite material is remarkably improved, the wave band of 340 GHz can be covered, and the wave-absorbing performance is excellent.

The invention discloses a resistance loading square ring ultra-wideband wave-absorbing structure which comprises a surface skin dielectric layer, an impedance matching dielectric layer, a resistance loading square ring functional layer, a functional layer substrate, a structure supporting dielectric and a conductive reflecting layer which are sequentially arranged from top to bottom. The resistor loading square ring functional layer is composed of N * N square ring loops, each square ring loop is composed of a plurality of conductive square plates and a plurality of resistors, the conductive square plates are connected through the resistors to form a closed loop of the square rings, and the conductive square plates and the resistors are evenly distributed on the loop. The resistor loading square ring ultra-wideband wave-absorbing structure is simple in structure, wide in wave-absorbing frequency band and efficient in wave-absorbing performance, ultra-wideband high-performance electromagnetic wave absorption can be achieved, and the resistor loading square ring ultra-wideband wave-absorbing structure has wide application prospects in the fields of stealth technology, RCS reduction, electromagnetic compatibility design and the like.

The invention discloses an electromagnetic wave absorbing material prepared on the basis of MXene waste precipitates as well as a preparation method and application of the electromagnetic wave absorbing material, and belongs to the technical field of nano materials and electromagnetic wave absorbing materials. The invention provides an electromagnetic wave absorbing material obtained on the basis of MXene waste precipitates, which is obtained by taking the MXene waste precipitates left after MXene is prepared by MAX phase etching as raw materials, collecting, drying and carbonizing. The carbonization treatment comprises the steps of putting the dried MXene waste precipitates into a crucible, putting the crucible into a tubular furnace, and carbonizing for 1-5 hours at the temperature of 400-1000 DEG C in an N2 atmosphere so as to obtain the electromagnetic wave absorbing material. The invention also provides a preparation method and application of the electromagnetic wave absorbing material. The method disclosed by the invention is simple, secondary utilization is performed on the MXene waste precipitate, and the wave-absorbing performance and the wave-absorbing bandwidth of the wave-absorbing material are effectively improved.

The invention provides an ultrahigh-frequency and ultra-wide-band composite electromagnetic wave-absorbing structure. The wave-absorbing material can achieve the radiation suppression effect of 10 dB or above at 20-30 GHz, and the wave-absorbing effect is obviously improved compared with the wave-absorbing effect obtained by independently using a commercial wave-absorbing material. The ultrahigh-frequency and ultra-wide-band composite electromagnetic wave-absorbing structure comprises a plurality of wave absorbing units which are arranged periodically; each wave absorbing unit comprises a top layer, a middle layer and a bottom layer which are sequentially arranged from top to bottom, the bottom layer is a metal back plate, the middle layer is a commercial electromagnetic wave-absorbing material, and the top layer is a Rogers RO4725JXR material.

The invention discloses a broadband ultrathin transparent wave absorber design, which comprises an ITO film and a plurality of wave absorbing units, the bottom of the ITO film is fixedly provided with the plurality of wave absorbing units, and each wave absorbing unit is composed of three ultrathin resistive film resonators, three polyethylene glycol terephthalate (PET) films and three polyvinyl chloride films. The three ultra-thin resistive film resonators are uniformly deposited on the tops of the three polyethylene glycol terephthalate (PET) films, the ultra-thin resistive film resonator on the top and the ultra-thin resistive film resonator in the middle are separated by a polyvinyl chloride film, and the thickness range of the polyvinyl chloride film is 2.5-3.5 mm. The ultra-wide-spectrum wave-absorbing material is designed on the basis of the double wave-absorbing structure layers and in combination with the square resistance of the resistive film, wave-absorbing peaks at low frequency, intermediate frequency and high frequency are achieved by reasonably selecting the surface resistance value and structure parameters of the resistive film, the low-frequency absorption strength is enhanced, the overall wave-absorbing bandwidth is widened, and the wave-absorbing performance at 4.6-24.4 GHz can be smaller than-10 dB.