79 results about "Stealth technology" patented technology

An asymmetric tetrahedral vortex generator that provides for control of three-dimensional flow separation over an underlying surface by bringing high momentum outer region flow to the wall of the structure using the generated vortex. The energized near-wall flow remains attached to the structure surface significantly further downstream. The device produces a swirling flow with one stream-wise rotation direction which migrates span-wise. When optimized, the device produces very low base drag on structures by keeping flow attached on the leeside surface thereof. This device can: on hydraulic structures, prevent local scour, deflect debris, and reduce drag; improve heat transfer between a flow and an adjacent surface, i.e., heat exchanger or an air conditioner; reduce drag, flow separation, and associated acoustic noise on airfoils, hydrofoils, cars, boats, submarines, rotors, etc. during subsonic or supersonic conditions; and, reduce radar signatures by using faceted edges with angles amenable to stealth technologies.

The invention provides a method for preparing magnetic ferroferric oxide/conductive polyaniline light-weight composite hollow microspheres, which relates to a method for preparing a magnetic ferroferric oxide/conductive polyaniline composite material. The invention solves the problems of high density and easy agglomeration of the traditional magnetic nanometer particle/conductive polymer composite material. The method comprises the following steps of: regulating ferrous chloride and ferric chloride solutions to be alkaline, adding sodium dodecyl benzene sulfonate and reacting to obtain ferroferric oxide; and modifying hollow glass microspheres by using poly(diallyldimethylammonium chloride) solutions after alkaline cleaning, then reacting the hollow glass microspheres with the ferroferric oxide, sequentially immersing obtained solid particles by using the poly(diallyldimethylammonium chloride) solutions and polystyrene sulfonic acid solutions, then adding the solid particles to aniline solutions, initiating polymerization by using ammonium persulfate, and washing and drying the solid particles to obtain the composite hollow microspheres. The composite hollow microspheres have both conductivity and magnetism, the density is 0.78-0.8g/cm<3>, and the composite hollow microspheres are not easy to agglomerate and are used for fields of military equipment stealth technology and civil anti-electromagnetic radiation.

The invention discloses a reflection-type ultra-wideband terahertz polarization reconfigurable circular polarizer, which is formed by M*N unit structures arranged periodically in the same horizontal plane. Each unit structure comprises a metal floor layer, a middle dielectric layer and a double-open resonant square ring structure layer, which are stacked up in sequence. The double-open resonant square ring structure layer is an anisotropic double-open square ring structure formed by two centrosymmetric L-shaped metal bars. The polarizer is high in practicality, can convert a linear polarized wave into a circular polarized wave efficiently within a terahertz ultra-wideband range, is simple in structure and easy to process, still has good linear-circular polarization conversion performance within a wide incidence angle range, and has a polarization reconfigurable characteristic; and besides, by adjusting structure parameters, the polarizer can be applied to other frequency bands and has a wide application prospect in the aspects of antenna design and stealth technology and the like.

The invention belongs to the technical field of a microwave technology and an aircraft stealth technology, and discloses a dual-band wave absorption frequency selective surface system, a design methodand an aircraft. The dual-band wave absorption frequency selective surface system is provided with a dielectric support plate, resistant thin film square rings and a circular-groove frequency selective surface, wherein the resistant thin film square rings are periodically arranged on an upper surface of the dielectric support plate, the circular-groove frequency selective surface is arranged on alower surface of the dielectric support plate and comprises a dielectric plate and a metal layer, the metal layer is arranged on an upper surface of the dielectric plate, the thickness of the metal layer is not considered, and circular grooves are periodically formed in the metal layer. By the dual-band wave absorption frequency selective surface system, k-band wave transparent/dual-band wave absorption can be achieved, an array pattern is compact, and good stability is achieved under an oblique incidence condition; the dual-band wave absorption frequency selective surface system is simple instructure; compared with a multi-layer structure, the dual-band wave absorption frequency selective surface system is only provided with the upper-layer resistant film, the intermediate-layer dielectric support plate and the lower-layer frequency selective surface, and is lighter and is lower in profile; and a transition band between the wave transparent band and the wave absorption band is small, and the wave absorption effect is good.

The invention relates to the field of electromagnetic stealth technology and radiation protection, and discloses a net-shaped layered-structure electromagnetic wave absorbing metamaterial. The electromagnetic wave absorbing material comprises: a first member (10) which at least includes one type of transparent flexible polymer materials and serves as an outer casing; a second member (20) which at least includes one type of flexible polymer materials and serves as a filling material between two metallic layers; a third member (3) which at least includes one type of metallic net-shaped structure and serves as a resonance net-shaped unit array. The third member (3) may adopt one type of metallic materials and may adopt plural metallic materials, and even alloy materials. The first member, the second member and the third member can all have many groups and form a multi-layered metamaterial structure. The layered-structure absorbing metamaterial of the invention increases absorbing width of electromagnetic waves and expands application range of the layered-structure absorbing metamaterial.

The invention discloses a preparation method of a wide-spectrum-antireflection-structure carbon aerogel. According to the method, the total mass percent of the resorcinol and formaldehyde and the resorcinol/sodium carbonate mass ratio are regulated, and the gelation time, the heating rate in the carbonization process and the sintering temperature are controlled, thereby obtaining the wide-spectrum-antireflection-structure carbon aerogel. The density range of the carbon aerogel prepared by the method is 20-60 mg/cm<3>, the specific area range is 1783-967 m<2>/g, the light reflectivity within the 400-2000nm ultraviolet-visible-near-infrared band is respectively lower than 0.3%, and the absorbance is respectively greater than 99.7%. The carbon aerogel can be used as a novel super black material, and is applicable to the fields of aerospace detecting sensors, solar photo-thermal converters, national defense stealth technology and the like.

The invention discloses a selective-radiation infrared stealth structure, and relates to the technical field of infrared stealth. The infrared stealth structure comprises a plurality of infrared selective heat emission units which are arranged and distributed in the form of a matrix according to a period p; each infrared selective heat emission unit comprises a substrate layer, a metal backboard, a dielectric layer and a metal sheet layer which are sequentially arranged from bottom to top; each metal sheet layer comprises a first metal sheet, a second metal sheet, a third metal sheet and a fourth metal sheet; and the first metal sheets, the second metal sheets, the third metal sheets and the fourth metal sheets are arranged on the dielectric layers by spacing by 90 degrees around the centers of the infrared selective heat emission units. The selective-radiation infrared stealth structure disclosed by the invention realizes selective thermal radiation through electromagnetic resonance characteristics of an infrared metamaterial, and realizes an infrared stealth technology through the transmitted spectrum design.

The invention relates to a design method of an active frequency selection surface, belongs to the fields of microwave technology and aircraft stealth technology, and solves the technical problems that a technology of the active frequency selection surface in the prior art is not expansible and a parasitic resonance phenomenon tends to occur under wide angle (0 to 50 degree) irradiation. The method comprises that electric-control lumped elements are loaded on the surface-mounted frequency selection surface of dense distribution periodically; the surface-mounted frequency selection surface loaded with the electric-control lumped elements is converted into a bridge network diagram, the bridge network diagram is displayed in an XOY planar rectangular coordinate system, the potentials at the two ends of each electric control lumped element are detected, and a pair of parallel isopotential lines is obtained from the bridge network diagram, namely, it is determined that the active frequency selection surface carries out feed along the parallel isopotential lines; and the designed active frequency selection surface is optimized. The design method can be widely applied in the fields including radomes, absorbing materials, omnidirectional scanning antennas and phased array radars.

A direct preparation of polyaniline solution from aniline monomer is carried out by: adding aniline monomer, water, emulsifier, organic solvent in certain ratio into a reactor, stirring fiercely to form emulsifying liquid, controlling reactive condition, adding oxidant to make emulsifying liquid after reaction finished, adding an emulsion breaker to produce a uniformity solution, settling to separate, removing water-phase, washing and separating, removing organic-phase solvent partly or completely through evaporation to obtain different concentration polyaniline or solid polyaniline. The polyaniline solution prepared by above method has excellent electrochemical performance and chemical stability, controllable conductivity. The synthesis is simple, and can be used in photoelectron appliance, transducers, molecular wires, and molecular appliance, electromagnetic shielding materials, metal anti-corrosion and stealth technology.

The invention belongs to the technical field of stealth technology and radar antennas, and particularly relates to a broadband wide-angle frequency selective surface radome, which is formed by arranging a plurality of basic units in an array mode. Each basic unit comprises a first dielectric layer, a second dielectric layer, a frequency selective surface layer and a third dielectric layer, which are sequentially arranged. The dielectric layers are symmetrically loaded and form the Chebyshev impedance converter with the frequency selective surface layers, so that the problems of narrow wave-transparent frequency band, low wave-transparent rate and unstable angle of the radome are solved; meanwhile, the frequency selective surface layer is formed by utilizing the metamaterial design principle; the radome is formed by arranging the basic units periodically in the form of a square, and comprises a uniquely designed miniaturized sub-wavelength periodic pattern; and compared with a multi-layer radome loaded with a metal mesh, a multi-layer metamaterial surface coupling form and other forms of frequency selective surfaces, the radome is wider in high-wave-transmission relative bandwidth and wider in angle application range, and is simple in structure and low in cost.

The invention discloses an ultra-thin electromagnetic wave absorber based on electrolyte-regulated graphene, and belongs to the technical field of microwave devices. The ultra-thin electromagnetic wave absorber comprises four layers of structures overlapped together, specifically including an electrolyte graphene layer, a high-resistance surface layer, a dielectric layer and a metal base plate, wherein the dielectric layer is arranged on the metal base plate, the high-resistance surface layer is arranged on the dielectric layer, and the electrolyte graphene layer is arranged on the high-resistance surface layer. According to the ultra-thin electromagnetic wave absorber based on electrolyte-regulated graphene provided by the invention, the electrolyte-regulated graphene technique is combined with the high-resistance surface layer to design a super wave absorbing device, the device is simple in structure, small in size and convenient to integrate, covers the broadband absorbing of X wave band, has the high absorptivity of more than 90%, is insensitive to incident angles and polarization angles of electromagnetic waves, is applicable to the fields of communication, household consumer electronics and military stealth technologies, and is very high in practicability.

The invention relates to a method for preparing a transparent electromagnet shielding layer material with a metal wire mesh. The shielding material comprises a surface electricity-conducting material and an electricity-conducting composite material. The method comprises steps that: stretching, the metal wire mesh and a resin film are pretreated; the pretreated metal wire mesh is put into a corrosive liquid for corrosion, namely, oxide treatment; the color change of the metal wire mesh is watched; the blackening is regulated by sodium polyacrylate in the corrosive liquid and changes with the content of the sodium polyacrylate; cleaning treatment is carried out after the corrosion and the metal wire mesh are gelatinized and cured; a film is laid flatly on a glass plate and evenly coated with the resin; the corroded metal wire mesh is laid on the resin-coated film, and then the metal wire mesh is coated with resin and covered with another film which is pressed with another glass plate after air bubbles are removed; then placing for 24 hours, the resin is cured naturally, or the curing is realized in a drying oven. The material produced by the method of the invention is applied to military technologies (for example: electronic warfare technology and stealth technology, safety products and various electronic products for civil use.

The invention discloses a filter of a thick screen frequency selective surface with a frequency conversion function, which relates to the field of radar detection and aims at further increasing the performance and the reliability of a stealth technology. The filter comprises a dielectric slab, an electric conduction metal plate, hole units and photosensitive materials, wherein the electric conduction metal plate is fixedly arranged on the dielectric slab, the hole units are uniformly distributed on the surface of the electric conduction metal plate, and the photosensitive materials are arranged at the middle part of each hole unit. According to the filter disclosed by the invention, a passing band and a stop band are provided for the frequency selective surface, the change of the passing band and the stop band can be adjusted through changing the illumination intensity of a light source, and thus the frequency selective surface has a variable transmission performance; and simultaneously, the device is easy to manufacture, and the cost is not so expensive.

A homogeneous core-shell composite material PPy @ PANI and a preparation method thereof. The invention relates to a core-shell composite material and a preparation method thereof and solves the problems that when a wave-absorbing material is prepared from polyaniline, a large quantity of auto-polymerization exists due to increase of the use amount of the polyaniline, thereby causing low use amount of the polyaniline, less coating quantity and non-uniformity of particles. In the homogeneous core-shell composite material PPy @ PANI, polypyrrole is employed as a core material and polyaniline is employed as a wall material. The preparation method includes following steps: (1) preparing PPy micro-spheres; and (2) dispersing the PPy micro-spheres into an acid solution, stirring the dispersion in ice-water bath, adding an aniline monomer and ammonium persulfate, performing a reaction in the ice-water bath, and cleaning and drying a reaction product to obtain the homogeneous core-shell composite material PPy @ PANI. A wave-absorption material prepared from the homogeneous core-shell composite material PPy @ PANI is thin in wave-absorption layer, is light in weight, is wide in absorption band and is strong in adsorption capability. The material can be used in the field of stealth technology and electromagnetic wave shielding.

Provided is a panel with an anti-radar detection function. According to IPC, the panel belongs to the physics class G01S 13/02, and is a system utilizing radio-wave reflection. The current anti-radar detection stealth technology is mostly confined to utilize wave-absorbing materials, and electromagnetic interference means, or a device possesses a contour structure of corner angles and planes, allowing radar wave detected by an opposite side to reflect in directions except exposure pathways, and the method has the disadvantages of high production, use and maintenance costs and unsatisfactory stealth effects; aiming to solve the problems, the invention provides the panel with an anti-radar detecting function. By utilizing the electromagnetic wave reflection principle that ''an incident angle is equal to a reflection angle'', and through mutual cooperation among regular blades on each hollow geometry inner wall, geometry inner cone and geometry inner wall of a plurality of combination panels, radar wave incoming from one side of a geometry opening can not reflect to the outside of the geometry, thereby possessing an anti-radar detecting function.

The invention discloses a composite wave-absorbing material preparation method which comprises the following steps: firstly, the hydrothermal synthesis method and the in-situ polymerization are adopted to prepare NiCuZn ferrite coated carbon nanotube/polythiophene composite material; then, structural characterization is adopted to research and analyze the functions of NiCuZn ferrite and polythiophene; finally, a sample vibration magnetometer, a four-point probe conductometer and a vector network analyzer are adopted to carry out performance tests respectively. The composite wave-absorbing material preparation method has the following advantages: the composite wave-absorbing material is wide in microwave absorption frequency band, small in material density, high in absorption efficiency and excellent in combination property, and plays an important role in the fields of stealth technology of military equipment, civil human body safety protection, communication anti-interference and electronic information privacy.

The invention discloses a method for detecting the wave-absorbing performance of a carbon nanotube wave-absorbing material, relates to a method for calculating an electromagnetic wave reflection coefficient, and belongs to the technical field of nondestructive testing. Carbon nanotubes are an important wave-absorbing material in the stealth technology, and detection and evaluation of the wave-absorbing performance of carbon nanotube wave-absorbing materials with different volume ratios are hot spot issues in engineering application research. In wave-absorbing performance detection mainly basedon electromagnetic wave reflection characteristics, a reflection coefficient curve comprises a lot of information in the aspect of wave-absorbing performance of the wave-absorbing material, such as -10dB bandwidth, reflection coefficient minimum value and center frequency. According to the invention, modeling is carried out based on electromagnetic wave reflection characteristics in the wave-absorbing material, a new method for characterizing the wave-absorbing performance of the carbon nanotube wave-absorbing material by using a reflection coefficient is proposed, and the dielectric characteristics of the carbon nanotube wave-absorbing material are quantitatively analyzed by using an equivalent resistance-capacitance network model; a layered medium propagation model is used for analyzingreflection characteristics of electromagnetic waves during propagation in a metal substrate wave-absorbing medium, characteristic parameters are extracted, and the detection of the wave-absorbing performance of the carbon nanotube wave-absorbing materials with different volume ratios is realized.

A missile image guiding system is mainly applied to an antiaircraft missile. A missile which has the advantages of resisting jamming ways like electronic jamming and infrared jamming and the like, and deactivating stealth technology and decoy flare technology of existing airplanes and the like can be designed through an electronic control system, a positioning device of an image tracking system, a target search method of the image tracking system, and a multiple image center point tracking method of the image tracking system.

The present invention provides a preparation method of photosensitive conductive polyaniline nanoparticles, which belongs to the field of functional polymer materials. The method for preparing the photosensitive polyaniline nanoparticles comprises the following steps: taking UV irradiation photo-crosslinked amphiphilic polymers micelle as polymerization template and a stabilizer, adding an initiator to polymerize an aniline monomer to obtain a solution containing the photosensitive polyaniline nanoparticles, centrifuging the solution and separating to obtain the photosensitive conductive polyaniline nanoparticles. The polyaniline enables stable dispersion in water; the obtained nano-particle dispersion has good film-forming property. The method of the present invention is simple, the yield is high, and the method is a green preparation method of photosensitive conductive polyaniline nanoparticles in an aqueous system. The size of the polyaniline particles is uniform, and the method of the invention has broad application prospect on optoelectronic devices, light-curing conductive coatings, conductive inks, sensors, nano-particle ink-jet printing, electronic shielding and stealth technology.

The invention discloses a frequency selective surface radome bandwidth compensation method, relates to the field of microwave technology and aircraft stealth technology, and in particular to a frequency selective surface radome bandwidth compensation method, which is applied to the design of frequency selective surface radomes that can cater to the requirements of aircraft stealth properties. The method comprises the following steps: firstly constructing a frequency selective surface radome structure, setting a resonant frequency and a maximum incoming angle of a frequency band, the maximum incoming angle determining the effective dielectric constant of a bandwidth compensation dielectric layer, the effective dielectric constant of the bandwidth compensation dielectric layer and the resonant frequency of the frequency band determining the structure parameters of the laminated structure of the dielectric layer; the bandwidth compensation dielectric layer adopting the laminated structure which is composed of two media having different dielectric constants. The method effectively addresses the problem of deformation of the bandwidth of the frequency selective surface radome due to changes of the incoming angles, makes up for the defects and deficiency of prior bandwidth compensation methods, and can be used in the optimization of the structures of frequency selective surface radomes.

The invention discloses an adaptive passive stealth method based on electromagnetic wave waveguide and a micro-nano-structure. The adaptive passive stealth method comprises steps of obtaining electromagnetic wave emitted by a target object background through a electromagnetic wave coupling unit, transmitting background electromagnetic wave to all parts of the target object through an electromagnetic wave transmission unit, and uniformly scattering the electromagnetic waves which are transmitted to all parts of the target object through an electromagnetic wave emission unit. As a result, the electromagnetic waves emitted by the object and the background are matched, which achieves the adaptive passive stealth of the target object. The adaptive passive stealth method based on the electromagnetic wave waveguide and the micro-nano-structure realizes the facts that the target object can be quickly and passively hidden according to the environment change and can be hidden in a wind range wave band which comprises the UV-visible light-infrared light wave band or even the microwave wave band. The noise interference in the active stealth technology can be avoided, the electromagnetic wave emitted by the object is similar to the electromagnetic wave by the environment, and the application range is wide.

The invention relates to a preparation method of metal nanometer powder, in particular to a nanometer iron powder special for shielding electromagnetic wave and radar wave in a glass cockpit of an airplane. The nanometer iron powder solves the problem that the existing nanometer metal powder can not completely shield the electromagnetic wave and the radar wave in the glass cockpit of the airplane. The preparation method comprises the steps of: machining raw materials into nanometer iron powder which has the shape of spheriform powder grain and has special stealth technology under the conditions that the temperature is -5 to 0 DEG C and the high-frequency cutting times is 5500-6000 times/minute; respectively screening out the powder material with centralized grain distribution with D3=21nm, D25=22.1nm, D50=25nm, D75=27.2nm and D97=30.3nm; and packaging in an anti-oxidation way, processing a surface and filling magnetism. The nanometer iron powder solves the problems of the film coating of an ion metallic coating reflecting film and the maintaining when in use, and can block the electromagnetic wave radiation between instruments of the airplane and the external part of a cockpit of the air such as equipment of aviators.

The invention belongs to the technical field of infrared stealth, and particularly relates to a preparation method for a high-temperature-resistant infrared low-emittance coating. According to the method provided by the invention, the coating does not need to be added with an adhesive, so the emittance is not increased at a high temperature; and moreover, the prepared coating is non-transparent inthe normal direction of 2 microns to 14 microns, and the coating provides benefits to an infrared stealth technology. Besides, a YSZ material is relatively good in heat insulation performance. Therefore, when the YSZ material is applied to preparation of a low-emittance coating, reduction of the temperature of a target surface is facilitated. In this way, the effect of reducing the infrared radiation intensity of an aircraft is doubled. Furthermore, in order to make sure that a YSZ coating is non-transparent in other directions, a YSZ/NiCoCrAIY composite coating is sprayed on a graphite substrate in advance, and then preparation of the YSZ coating and stripping of the graphite substrate are carried out on the surface of the composite coating.