10results about How to "Absorption Bandwidth" patented technology

The invention relates to a multi-absorption-band ultra-wideband common-mode filter based on a mixed resonator structure. The multi-absorption-band ultra-wideband common-mode filter comprises a coupling microstrip line, a dielectric substrate, a main resonator, an auxiliary resonator and a resistor, the filter has an upper surface and a lower surface, and a coupling microstrip line comprises a metal conduction band located on a dielectric substrate and a metal ground layer located below the dielectric substrate; two ends of the coupling microstrip line are respectively connected with the input port and the output port; the main resonator is etched in the middle of the metal ground layer; the auxiliary resonator is etched on the outer side of the main resonator in the metal ground layer; the coupling microstrip line is mutually coupled with the main resonator and the auxiliary resonator to realize mixed resonance; the resistor crosses the gap of the auxiliary resonator at the intersection of the auxiliary resonator and the symmetric line, and the two ends of the resistor are connected with the metal ground layers inside and outside the metal conduction band; according to the invention, the ultra-wideband common-mode suppression bandwidth and a plurality of absorption bands are provided, and the absorption bands dissipate common-mode noise in the form of heat energy, so that the problem of potential common-mode electromagnetic interference in the system is reduced, and normal transmission of differential-mode signals is not damaged at the same time.

The present invention provides a FeNiHo / carbon nanofiber composite absorber and a preparation method thereof, an absorbent material and a preparation method thereof, and belongs to the technical field of electromagnetic wave absorbing materials. The present invention first mixes iron salt, nickel salt, holmium salt and polyvinyl pyrrolidone in a mixed solvent, and electrostatically spins the obtained spinning precursor solution to obtain a nanofiber membrane; the nanofiber membrane is sequentially subjected to pre-oxidation treatment and carbonization treatment to obtain a FeNiHo / carbon nanofiber composite absorber. The FeNiHo / carbon nanofiber composite absorber, paraffin and petroleum ether are mixed, and then pressed and irradiated with ultraviolet light to obtain an absorbing material. The FeNiHo alloy nanoparticles in the composite absorber improve the impedance matching performance and electromagnetic wave attenuation ability of the carbon nanofiber. The obtained absorbing material can achieve the purpose of real-time adjustment of the absorption frequency by irradiation with ultraviolet light.

The invention provides a middle and far infrared broadband metamaterial absorber and a design method thereof. The middle and far infrared broadband metamaterial absorber comprises metamaterial absorption units which are arranged in a periodic array mode. The whole metamaterial absorption unit is square and comprises a top metal layer, a dielectric layer and a bottom metal layer from top to bottom in sequence. The top metal layer is attached to the upper surface of the dielectric layer and is formed by arranging eight metal sheets according to a certain arrangement mode, namely a circular metal sheet which is arranged at the central position of the upper surface of the dielectric layer, and the center of the circular metal sheet is aligned with the center of the upper surface of the dielectric layer; three annular metal sheets concentric with the circular metal sheet surround the periphery of the circular metal sheet, and gaps exist between the circular metal sheet and the annular metal sheet on the innermost layer and between the annular metal sheets on the adjacent layers from inside to outside. And the four metal square sheets with the same size are respectively arranged at four corners of the upper surface of the dielectric layer. The absorption bandwidth is greatly prolonged, and perfect absorption of a target wave band can be infinitely approached by adjusting geometric parameters of the absorber.

The invention provides a wave-absorbing honeycomb material and a preparation method thereof. The wave-absorbing honeycomb material comprises an aramid paper honeycomb substrate, and a foam absorbing layer, an optional foam transition layer and a foam matching layer which are sequentially arranged in honeycomb holes of the aramid paper honeycomb substrate from outside to inside, wherein the dielectric constant of the foam matching layer is gt; the dielectric constant gt of the foam transition layer; the foam absorbs the dielectric constant of the layer. According to the wave-absorbing honeycomb material, the technical effects of improving the broadband absorbing effect and reducing the thickness are achieved.

The application discloses a carbon-composite high-entropy metal oxide electromagnetic functional material and a preparation method thereof, and relates to the technical field of microwave absorbing materials. The electromagnetic functional material is composed of (Fe 0.2 Co 0.2 Ni 0.2 Mn 0.2 Cr 0.2 )3O4 / C, and the preparation method comprises the following steps: adding equimolar iron salt, cobalt salt, manganese salt, chromium salt and nickel salt into water together with urea, polyvinylpyrrolidone and a carbon source to configure a mixed solution, then heating and reacting, centrifuging and drying the reaction product after the reaction is completed, and obtaining the electromagnetic functional material. By introducing the carbon material with high dielectric constant, the electric conduction performance and the electric loss performance are enhanced, the impedance matching is optimized, the overall density is reduced, the absorption bandwidth is widened, the effective absorption bandwidth covers the full wave band of 2-18GHz, the electromagnetic functional material is suitable for multi-wave bands, and the problems of low absorption rate and narrow frequency band are solved. Moreover, the preparation process is simple, and the one-time hydrothermal reaction can be completed, so that the scale production is facilitated.

This invention discloses a dielectric-magnetic synergistic loss type electromagnetic wave absorbing material, its preparation method, and its application. The dielectric-magnetic synergistic loss type electromagnetic wave absorbing material of this invention comprises rGO aerogel and Ni distributed in the rGO aerogel. x Co 1‑x Fe2O4 magnetic nanoparticles x The range of values ​​for is 0≤ x ≤1. The preparation method of the dielectric-magnetic synergistic loss type electromagnetic wave absorbing material of the present invention includes the following steps: mixing graphene oxide and Ni x Co 1‑x Fe2O4 magnetic nanoparticles are dispersed in water, then subjected to a hydrothermal reaction, followed by freeze-drying. The dielectric-magnetic synergistic loss-type electromagnetic wave absorbing material of this invention possesses advantages such as low density, small matching thickness, wide absorption bandwidth, high absorption intensity, and flexible adjustment of composition and properties, making it a promising candidate for applications in radar stealth and electromagnetic protection.

The utility model relates to the technical field of textiles, and discloses a sound-absorbing carpet and a vehicle. The sound-absorbing carpet sequentially comprises a lower layer (1), a gradient density fiber felt layer (2) and an upper hard layer (3) from bottom to top, the density of the gradient density fiber felt layer (2) is sequentially increased from bottom to top, and the density of the gradient density fiber felt layer (2) is smaller than that of the fiber felt layer (3). According to the sound-absorbing carpet, the low-frequency sound-absorbing capability of the automobile carpet can be improved, and wide range and strong sound absorption are realized.

The application provides a magnetic metal powder / porous carbon composite material, a preparation method and application thereof. The preparation method comprises the following steps: step S1, performing surface oxidation reaction on a magnetic carbonyl metal powder to form pretreated metal powder; step S2, dissolving a copolymer PS n -b-PEO m in a first solvent, adding a mixed solution of ethanol and water into the first solvent to obtain a milk emulsion; step S3, adding the pretreated metal powder, pyrrole and FeCl3 into the milk emulsion to perform in-situ polymerization reaction, so as to form a precursor and obtain a precursor solution; step S4, removing the spherical PS n -b-PEO m micelles in the precursor by a solvothermal method, and then drying to obtain a porous precursor; and step S5, calcining the porous precursor under an inert atmosphere to obtain the magnetic metal powder / porous carbon composite material. The magnetic metal powder / porous carbon composite material prepared by the application has better wave absorption performance in a low frequency band.

The invention discloses a NiCo-MOF derived carbon nanotube wave-absorbing material with a core-shell structure and a preparation method of the NiCo-MOF derived carbon nanotube wave-absorbing material, and relates to the technical field of wave-absorbing materials. According to the method, NiCo-MOF with a core-shell structure is obtained by controlling the solvent proportion, then a carbon nano tube grows on the surface of the NiCo-MOF in situ, the prepared MOF-derived carbon nano tube has a hollow core-shell structure, and the surface of the MOF-derived carbon nano tube is covered with a layer of dense carbon nano tube. By adopting the structure, the conductivity of the material is greatly improved, the types of interface polarization are enriched, and good wave absorbing performance is shown in the frequency band of 2-18 GHz; the hollow structure is beneficial to multiple reflection of electromagnetic waves inside, and when the matching thickness is 2.5 mm, the effective absorption bandwidth can reach 5.7 GHz, and the minimum absorption peak reaches 4.8 GHz. The method is simple in technological process, low in cost and suitable for large-scale preparation, and has wide application prospects in the fields of light broadband wave absorption, thermal protection and the like.

This invention belongs to the field of coloring pigments and their preparation technology, specifically relating to an ion-absorbing silicate coloring pigment. The general formula of its initial raw materials is: x AX 1 / δ · m MX 2 / δ · n SiX 4 / δ · y REX 2或3 / δ A carbon source is added, and the mixture is calcined at 900-1500℃ in an inert or reducing atmosphere for 1-50 h to obtain an ion-absorbing silicate coloring pigment. The resulting pigment can achieve continuous coloring in the blue-green to red-orange visible light region under sunlight. This ion-absorbing silicate inorganic coloring pigment is non-toxic, exhibits strong absorption in the blue-green light region with a wide absorption band, and overcomes the shortcomings of the aforementioned functional luminescent pigments, such as weak light absorption, extremely poor coloring performance, and unstable coloring. It also possesses many advantages that make it an ideal coloring pigment, including abundant and inexpensive raw materials, stable physicochemical properties, simple synthesis conditions, good compatibility with glass and ceramics, and environmental friendliness during preparation and use.