16 results about "Broadband absorption" patented technology

The application claims a kind of multiband terahertz absorber based on laminated graphene structure, which is a laminated stack structure.The positive terminal of external power supply is connected to two layers of graphene, and the negative terminal is connected to a gold reflection layer.The Fermi energy level of graphene is controlled by voltage.The structure parameters of each layer, graphene and dielectric layer material characteristics are set.The absorber forms multiple absorption peaks in the 1~5 THz frequency band, with a peak absorption rate of over 90%.At 1.60 THz, a narrowband absorption of 93% is achieved, and at 2.54~4.28 THz, a broadband absorption with a relative bandwidth of 51% is achieved.The normalized equivalent impedance at the resonance frequency point is nearly perfectly matched with the free space impedance.The absorber also has good polarization angle insensitivity, with only slight absorption performance attenuation within an incident angle range of 0~60°.The absorption characteristics can also be adjusted by adjusting the key geometric parameters.The application can simultaneously achieve narrowband and broadband absorption, with excellent absorption performance, and is suitable for interference signal filtering in terahertz communication systems.

This invention relates to a method for preparing a broadband absorption hydrogel. The method comprises the following steps: S1, mixing solvent A (N,N-dimethylformamide or acetonitrile) with deionized water to obtain a mixed solvent; S2, adding polyethylene glycol methyl ether acrylate-480 and acryloylmorpholine to the solvent in S1 and dissolving them to obtain a mixed solution; S3, removing dissolved oxygen from the mixed solution in S2, sealing the container, and stirring under ice bath conditions; S4, adding potassium persulfate and N,N,N',N'-tetramethylethylenediamine to the mixed solution after stirring in S3, and sealing the container again; S5, completing the polymerization reaction in the container at 60 °C to obtain the hydrogel. Compared with the prior art, the hydrogel material provided by this invention has improved reflection loss intensity and effective absorption bandwidth performance, thus providing a new perspective for developing highly flexible and efficient electromagnetic wave absorbers.

This invention discloses a broadband duct silencing structure combining perforated tubes and cavities. The structure uses a galvanized housing as its main body, with perforated tubes coaxially arranged inside. A perforated partition divides the structure into front and rear silencing chambers. The front silencing chamber contains a first sound absorber and an air layer, forming a Helmholtz resonant cavity to efficiently eliminate low-frequency fan noise. The rear silencing chamber is filled with a second sound absorber and is equipped with perforated tubes, micro-perforated tubes, and micro-perforated inserts with progressively smaller apertures, forming a gradient microporous structure to achieve broadband absorption of mid-to-high frequency noise. The structure utilizes the airflow in the duct to drive the impeller to rotate, which in turn drives a bidirectional reciprocating screw via bevel gear transmission. This drives a delivery rod and a one-way valve to form a directional airflow circulation. The sound absorber is automatically purged through the air duct and comb-shaped air duct to remove fiber dust, preventing secondary pollution and stabilizing acoustic performance. This invention combines the advantages of low-frequency resonance silencing and mid-to-high frequency gradient microporous sound absorption, featuring a compact structure, wide silencing bandwidth, and stable and reliable operation.

This application relates to the technical field of microwave absorbing materials, and in particular to a high-power electromagnetic compatibility (EMC) composite microwave absorbing material and its preparation method. The high-power EMC composite microwave absorbing material comprises an aramid paper honeycomb core and a microwave absorbing resin composite solution coated on the surface of the aramid paper honeycomb core. The microwave absorbing resin composite solution comprises the following raw materials in parts by weight: 2-7 parts microwave absorber, 30-40 parts solvent-based binder, 1-5 parts dispersant, 0.1-0.8 parts additives, and 50-65 parts solvent. The high-power EMC composite microwave absorbing material prepared by this application has the advantages of withstanding high-power radiation, good broadband absorption performance, and stable product performance, meeting the core requirements of EMC anechoic chambers for microwave absorbing materials.

This invention relates to a method for preparing Ag₂O-Bi₄O₅I₂ broadband absorption heterojunction photocatalyst and its application in microreactors, belonging to the field of photocatalyst preparation technology. This invention utilizes a chemical precipitation method to support broadband-absorbing Ag₂O on the surface of Bi₄O₅I₂ nanosheets, constructing a heterojunction to achieve separation of photogenerated carriers. The prepared Ag₂O-Bi₄O₅I₂ composite material also exhibits excellent broadband absorption. The composite with Ag₂O nanoparticles further increases the reactive sites on the Bi₄O₅I₂ nanosheets, further enhancing its photocatalytic performance. Coating it onto a glass surface to prepare a microreactor increases the heating rate and reaction temperature of the photothermal catalyst in liquid-phase catalysis, improving the photocatalytic degradation effect. The composite material prepared by this invention shows good performance in the photocatalytic degradation of tetracycline, helping to solve the current problem of excessive antibiotics that are difficult to degrade in wastewater.

This invention belongs to the field of metamaterials technology, specifically relating to an adjustable integrated absorption and reflection metamaterial structure. It includes several basic units arranged in a periodic array. Each basic unit comprises a resonant unit, a dielectric layer, and a reflector layer stacked sequentially. The dielectric layer is deformable to create a cavity between itself and the reflector layer or to fit tightly against it. The resonant unit includes four sequentially connected arc-shaped segments arranged centrally symmetrically. The ends of adjacent arc-shaped segments connect to form sharp corners extending towards the center of the resonant unit, with a gap between opposing sharp corners. This invention offers good reconfigurability, high flexibility, and deformability, allowing for easy adjustment of the state and switching of operating modes according to actual usage needs, achieving broadband absorption or complete reflection functions from 4.9 GHz to 16.3 GHz.

This invention belongs to the field of frequency-selective surfaces and electromagnetic absorption materials, and relates to a broadband low-pass frequency-selective absorber. It comprises multiple structural units arranged in a rectangular array. Each structural unit includes an absorption layer, a first transmission layer, a second transmission layer, and a third transmission layer, sequentially arranged and fixedly connected by insulating connecting pillars. Support structures are provided between adjacent layers, correspondingly forming foam layers one, two, and three. The absorption layer includes a first dielectric substrate and a loss-absorbing structure thereon. The first transmission layer includes a second dielectric substrate and a first metal square ring structure thereon. The second transmission layer includes a third dielectric substrate and a spiral metal strip structure thereon. The third transmission layer includes a fourth dielectric substrate and a second metal square ring structure thereon. This invention features a small unit structure size and low profile, achieving low insertion loss transmission in the low-frequency band, broadband absorption in the high-frequency band, and stable performance under large-angle incident light.

The application belongs to the field of micro-nano photonics and infrared sensing, and relates to an infrared broadband absorption metasurface structure. A structure of metal layer-dielectric layer-metal layer is adopted, the upper and lower metal layers adopt platinum, the dielectric layer uses traditional material silicon, and array arrangement is realized by combining different size sub-units, an infrared broadband absorption metasurface based on a square bevel structure is designed, and an average absorption rate of more than 60% in the 8-13um atmospheric window band is realized. The bottom metal and the dielectric layer are uniform layer structures, and the top metal layer adopts a square bevel of one angle, the ratio of the bevel to the square side length is related to the absorption wavelength. The application regulates the light field based on micro-nano structure parameter change, has good wavelength selectivity and modulation performance, the selected material has good chemical stability, and has practicability and process compatibility.

The present application discloses a kind of stacked structure's ultra-wideband terahertz absorber design, which is composed of doped silicon substrate and three layers of doped silicon covered with cycloalkene-based copolymer (Topas). The research results show that the absorber exhibits a high absorption rate of more than 90% in the frequency range of 0.5 THz to 10 THz, with an absorption bandwidth of 9.5 THz and a relative bandwidth ratio of 180.95%. To verify the absorption performance of the proposed doped silicon and Topas stacked structure, this paper conducts absorption spectrum test and analysis on six different structures. Under the condition of keeping other parameters constant, the absorption spectrum characteristics under different structures are compared and analyzed. In addition, by analyzing the impedance matching theory, the mechanism behind the wideband absorption and high absorption rate is studied. The composition, geometry and arrangement of the array significantly affect the absorption performance of the device. The designed terahertz absorber adopts simple materials and structure, and has great potential in applications such as sensing, terahertz detection and thermal imaging.

This invention discloses a broadband metamaterial absorber based on a swastika shape, comprising multiple absorbing units, each including a reflective layer; a dielectric substrate disposed on the reflective layer; and an ITO thin film resonant layer disposed on the dielectric substrate. The resonant layer has a cross-shaped structure. First extensions extend from the four ends of the resonant layer, making it swastika-shaped. Second extensions extend perpendicularly from the four first extensions, and the first and second extensions connect to form a corner structure. The circuit resonance in this invention is stable. When the surface impedance matches the free-space impedance within a wide bandwidth, electromagnetic waves of different frequencies can effectively enter the absorber and be absorbed, achieving broadband absorption. The addition of a corner structure to the resonant layer not only increases the length of the current path, thereby increasing the equivalent inductance, but also increases the propagation path length of electromagnetic waves within the metamaterial, thus broadening the absorption bandwidth.

This invention provides a frequency-selective absorber based on dual-layer synergistic coupling and its application, belonging to the field of functional materials technology. The structure includes a loss layer and a bandpass frequency-selective surface layer, with an air layer between the two layers. The loss layer includes a first dielectric substrate and first and second metal patches with I-shaped derivative patterns on its upper and lower surfaces, each with a resistor loaded on it. The bandpass frequency-selective surface layer includes a second dielectric substrate and a third cross-shaped slotted metal patch on its upper surface. This invention achieves broadband absorption in the absorption band and low insertion loss transmission in the transmission band through the synergistic coupling of the loss layer and the bandpass layer. When this structure is placed above an antenna, it can effectively reduce the radar cross-section of the antenna system while ensuring antenna radiation performance. This structure has advantages such as wide absorption bandwidth, low transmission insertion loss, and good angular stability, making it suitable for radar stealth and electromagnetic compatibility applications.

This invention discloses a low-frequency flexible microwave absorbing composite material based on the localized field enhancement effect and its preparation method, relating to the field of electromagnetic protection technology. It aims to solve the problems of large thickness and difficult conformal design of complex curved surfaces in traditional microwave absorbing structures at low frequencies. The composite material comprises, from top to bottom: a flexible metasurface patterned layer with specific sheet resistance and topological array, a flexible polymer dielectric layer dispersed with modified magnetic filler, and a bottom total reflection layer. This invention utilizes the strong localized electromagnetic field excited by the metasurface to focus and penetrate into the dielectric layer, amplifying the dissipation potential of the magnetic filler; simultaneously, the bulk loss of the dielectric layer generates reverse damping on the metasurface resonance, thus broadening the bandwidth. This synergistic mechanism breaks the quarter-wavelength limitation. The preparation method includes pattern layer molding, dielectric layer mixing and curing, and overall composite molding. This invention achieves high-efficiency low-frequency broadband absorption at a single-layer subwavelength thickness, while also possessing excellent flexibility, making it highly suitable for stealth on complex curved surfaces with total reflection boundaries.

A gradient impedance-gradient multi-fiber hybrid broadband absorbing structure is provided, comprising a multi-fiber preform and a low-loss matrix. The low-loss matrix fills within the multi-fiber preform and covers it, with a covering thickness of <0.2 mm. The multi-fiber preform is formed by weaving together high-loss, medium-loss, and low-loss fibers. The multi-fiber preform includes an impedance matching layer formed by low-loss fiber weaving, an impedance transition layer formed by mixing low-loss and medium-loss fibers, and an absorption attenuation layer formed by mixing medium-loss and high-loss fibers. The impedance matching layer, impedance transition layer, and absorption attenuation layer are stacked sequentially to form a three-dimensional structure. This invention can effectively control its microwave electromagnetic characteristics, achieve a reasonable impedance gradient change, and significantly improve broadband absorption performance.

This invention provides a composite material with both broadband absorption and transmission functions. The material comprises the following layers in sequence: a metal FSS layer, a first subwavelength structural film layer, a first glass fiber reinforced substrate, a first foam layer, a second subwavelength structural film layer, a first glass fiber composite FSS layer, a second foam layer, a third subwavelength structural film layer, a second glass fiber composite FSS layer, a third foam layer, and a second glass fiber reinforced substrate. Adjacent layers are bonded together. The metal FSS layer is located on the outermost side and serves as a bandpass filter and impedance adjustment unit. The first and second glass fiber composite FSS layers are located on the inner side, with different patterns and sheet resistance values. They utilize ohmic loss and electromagnetic resonance of the dielectric layer to dissipate electromagnetic wave energy, achieving efficient transmission in specific frequency bands while exhibiting broadband strong absorption characteristics in out-of-band frequencies. Through the cooperation between the layers, the transmittance can exceed 80% in a specific frequency band of the S-band, and the absorption rate can exceed 80% in the X and Ku bands.

This invention discloses a method for preparing metal / nitrogen-doped helical carbon nanotube microwave absorbing materials. The invention aims to address the technical problems of existing microwave absorbing materials, such as limited energy loss mechanisms, high filler ratios and densities, narrow microwave absorption bandwidth, and limited functionality, hindering their widespread application. This invention prepares high-performance M / N-HCNTs by in-situ loading metal ions into a helical carbon nanotube matrix and then performing an external thermal-driven process. The unique atomic configuration of M-N-C and the unique geometric configuration of the helical structure enable orbital coupling, spin polarization, and cross-polarization, synergistically regulating the electromagnetic wave absorption characteristics of the material. This material exhibits strong attenuation capabilities, broadband absorption, and excellent microwave absorption performance, making it highly valuable for both civilian and military applications.