21 results about "Stealth technology" patented technology

This invention discloses a method for preparing and controlling the emissivity of infrared stealth MXene thin films, belonging to the field of infrared stealth technology. The method uses Ti3C2T... X Using MXene as a raw material, it is coated onto a graphite plate as the anode and a platinum mesh as the cathode. Electrolysis is performed for 5 minutes in a tannic acid-sodium chloride aqueous electrolyte at 5V. After ultrasonication, centrifugation, and washing, e-MXene is obtained. The e-MXene film is then obtained by filtration, or it can be composited with BC nanocellulose to obtain an e-BC-MXene film. This invention achieves efficient MXene modification through anodic electrochemical exfoliation. The synergistic effect of tannic acid and sodium chloride enhances its antioxidant properties and structural integrity. The resulting film can be water-controlled by humidity and electrothermally controlled by current. Compared with the traditional cathode exfoliation method, the yield, sheet size, and control responsiveness are significantly improved. The preparation process is green and low-consumption. The film is suitable for adaptive infrared stealth requirements in complex scenarios and has broad application prospects.

The application relates to a variable sweep wing stealth aircraft afterbody wedge shape design method, and belongs to the field of aircraft general design and stealth technology. The application is simple and practical in shape; comprehensive design factors are considered, and comprehensive requirements such as variable tail wing rotation, component coupling, stealth principle and aerodynamic resistance are covered; design constraints can be accurately converted into geometric design; variable tail wing rotation, the stealth principle, aerodynamic resistance and component coupling can be effectively converted into afterbody wedge shape point position and line tangent vector control design to be realized; the fusion design of the afterbody wedge and the surrounding curved surface is better realized; under the premise of guaranteeing the variable tail wing rotation space requirement and the binary nozzle requirement, the aerodynamic and stealth shape integration design of the afterbody wedge shape is realized. The application is mainly applied to the scheme design of the afterbody wedge shape of the variable tail wing. The method is novel, ingenious and compact in structure, has strong applicability, has a wide application range, and has a wide application prospect in the design of military aircraft.

The invention discloses a broadband electromagnetic dipole antenna based on an X-shaped polarization conversion metasurface, and belongs to the technical field of electromagnetic dipole antennas. In order to solve the problems that an existing metamaterial wave absorber RCS is narrow in reduction bandwidth, an RCS antenna of a PCM chessboard structure is concentrated at the frequency band below 20 GHz and the like, the electromagnetic dipole antenna combines a 1 * 8 electromagnetic dipole array with the PCM chessboard structure, and the RCS is minimized while high gain and wide frequency band are kept; by using the X-shaped PCM unit and the mirror image unit array thereof, cross polarization conversion of reflected waves is realized in a working frequency band, a 180-degree phase difference is generated, the PCM disperses back scattering energy to a surrounding area, and normal reflection is reduced, so that the RCS of the antenna is effectively reduced, and the RCS is reduced by more than 10 dB in 74.1% of bandwidth (19.07-41.52 GHz). The electromagnetic dipole antenna disclosed by the invention has the characteristics of high gain, wide bandwidth and low RCS (radar cross section), has a wide application prospect in the fields of high-frequency wireless communication and radar stealth, and shows huge potential of future development of a stealth technology.

The invention relates to the technical fields of electromagnetic sensing, stealth technology and electromagnetic wave regulation and control. An existing sensor structure still has the limitations that invisibility, signal enhancement and stable electric connection cannot be achieved at the same time, and the sensitivity and the invisibility performance restrict each other. The invention discloses an electromagnetic sensor stealth structure capable of enhancing sensitivity, which is characterized in that a plurality of hidden areas and a high-refractive-index core detection area are arranged in an anisotropic medium shell layer, and sub-wavelength communication holes are formed between the hidden areas and the high-refractive-index core detection area; electromagnetic waves can be guided to bypass the sensor main body to realize invisibility, meanwhile, the electromagnetic waves are converged to a high-refractive-index core detection area to realize signal enhancement, and the effect of stable electric connection between the sensor main body and the probe is maintained; the method is applied to the fields of ultra-weak signal detection, stealth monitoring, biosensing, radar detection and the like.

The application discloses a Jerusalem unit double-layer FSS broadband wave-absorbing structure and a preparation method and application thereof, and belongs to the field of electromagnetic wave-absorbing technology design in electromagnetic stealth technology. The structure is sequentially arranged from bottom to top as a metal bottom layer, a dielectric layer 1, a patterned resistance layer 1, a dielectric layer 2 and a patterned resistance layer 2. Periodic array distributed multiple unit cell structures are formed on the surfaces of the patterned resistance layer 1 and the patterned resistance layer 2, and each unit cell structure adopts a Jerusalem cross pattern. The Jerusalem unit double-layer FSS broadband wave-absorbing structure provided by the application has a wide-frequency absorption characteristic. Through the regulation of geometric sizes on a macro scale and the structure design on a micro scale, the wave-absorbing structure can realize an absorption rate of more than 99% in a full frequency band of 8-12 GHz, and has a good absorption effect on low-frequency electromagnetic waves.

The invention relates to the technical field of wave-absorbing materials, and particularly discloses a CaMnO3 / CoNi composite wave-absorbing material and a preparation method thereof. The material takes dielectric loss type CaMnO3 as a matrix, and magnetic loss type CoNi nanoparticles are coated by a liquid phase reduction method to form a heterojunction composite structure. By regulating and controlling the mixing ratio of CaMnO3 to CoNi, the impedance matching characteristic of the material is obviously optimized, and the synergistic enhancement of dielectric loss and magnetic loss is realized. Experiments show that when the thickness of the material is 3.2 mm, the material reaches the minimum reflection loss of 26.6 dB at 8.48 GHz, the effective wave absorbing bandwidth reaches 4.09 GHz, and the performance of the material is obviously superior to that of a single CaMnO3 or CoNi material and a CaMnO3 / Co composite material. The method is simple in preparation process, low in cost and suitable for the fields of electromagnetic shielding, stealth technologies and the like.

The invention belongs to the technical field of electromagnetic stealth, and discloses a frequency selective surface unit and a reconfigurable frequency selective surface. The frequency selection surface unit adopts a cascade unit structure of four metal layers and three dielectric layers, and a PIN diode, a feed connecting line, a square patch, a double-square-ring patch shaped like a Chinese character'hui ', a single-square-ring patch and the like are combined to form a filtering structure with good performance. According to the reconfigurable frequency selective surface, lower passband insertion loss, wider passband, better incident angle stability, narrower transition band, better out-of-band rejection and good polarization stability are achieved, and the problems that an existing reconfigurable frequency selective surface is insufficient in passband bandwidth, poor in out-of-band rejection and the like are solved. According to the reconfigurable frequency selective surface, the PIN diodes and the patch structures on all the units are connected through the metal feed connecting lines, so that after the array structure is formed, all the units can be fed only by feeding a certain unit, the design of an extra feed network layer is avoided, and the unit structure is simplified.

The invention relates to the technical field of terahertz metamaterial devices, in particular to a dynamic switchable broadband terahertz wave absorber based on vanadium dioxide. The insulator-metal reversible phase change characteristic of vanadium dioxide is utilized to realize effective regulation and control of the conductivity; through the innovative design of the top layer resonance pattern, the wave absorber achieves efficient wave absorption with the average absorption rate exceeding 90% at the frequency band of 5.9-12.4 THz in the vanadium dioxide metallic state, the absorption bandwidth is 6.5 THz, and the relative bandwidth is 71.6%. The wave absorber has quadruple rotational symmetry, polarization insensitivity and excellent oblique incidence stability, and the absorptivity of TE polarized waves within the incidence angle range of 0-60 degrees and the absorptivity of TM polarized waves within the incidence angle range of 0-40 degrees are both maintained to be 80% or above; the average absorptivity of vanadium dioxide in an insulation state is lower than 1%, and a dynamic switch with a wave absorbing function is realized. The device is simple in structure, high in design robustness and high in preparation feasibility, and can be widely applied to the fields of terahertz imaging systems, high-speed communication electromagnetic compatibility shielding, high-performance radar stealth technologies and the like.

The invention discloses a wide-angle stable ultrathin low-frequency wave absorber based on an electromagnetic metamaterial, and belongs to the technical field of artificial electromagnetic structures and radar stealth. A core of the wave absorber is of a multi-layer composite structure formed by a plurality of wave absorbing units which are periodically arranged in a hexagonal honeycomb shape in space, and each unit comprises a copper-based resonance layer etched with three curve narrow slits, an epoxy plate layer, a hexagonal patch layer, a high-molecular polymer layer and a conducting substrate layer from top to bottom. Through the special geometric configuration and the spatial alignment relationship of the resonance layer and the patch layer, and in combination with the lamination design of the sub-wavelength thickness (0.908 mm), efficient absorption with the reflection loss superior to-19.7 dB is realized at the low frequency of 0.21 GHz, and the relative thickness is as low as lambda 0 / 1573. The structure has excellent angle and polarization stability at the same time, the resonant frequency deviation is smaller than 5 MHz in the incidence range of 10-70 degrees, and the absorption performance is kept consistent in the full polarization range of 0-180 degrees. The invention effectively solves the problems of'thickness-performance 'contradiction and angle sensitivity of the traditional wave-absorbing material in a low-frequency band, and provides a high-performance solution for the fields of radar stealth, electronic countermeasure, electromagnetic compatibility and the like.

The invention relates to the field of electromagnetic metamaterials, stealth technology and weak target detection, and aims to solve the problem that the scattering cross section of a miniature platform with an extremely small geometric size is extremely low, and the miniature platform with the extremely small geometric size is difficult to effectively find and track by a traditional radar detection means. The invention discloses an electromagnetic scattering enhancement device with a stealth function and a weak target detection method, a coaxial nested structure is adopted, the electromagnetic scattering enhancement device sequentially comprises a balance dielectric cylinder, a sensing cavity for accommodating a to-be-detected object and a multi-layer dielectric shell from inside to outside, and through the electromagnetic and geometric parameter distribution design of the balance dielectric cylinder and the multi-layer dielectric shell, the sensing cavity is used for accommodating the to-be-detected object. The dual functions of no-load stealth and load amplification are achieved under the preset working frequency, a high-gain response mechanism for tiny disturbance is established through the balance dielectric cylinder, signal amplification of a weak target is achieved, and the robustness of compensating machining errors through parameter adjustment of the balance dielectric cylinder is achieved. The method can be widely applied to the fields of micro target detection, self-adaptive detection and safety protection.

The present application belongs to the field of infrared-laser stealth technology, and discloses a radar wave-transparent infrared-laser stealth film, which comprises, from bottom to top, a substrate, a photonic crystal multilayer film structure and a top surface patterning structure; the photonic crystal multilayer film structure is composed of two kinds of transparent medium materials with high and low refractive indexes alternately stacked and arranged; the top surface patterning structure is used for realizing surface phase control; by using the constructive interference effect of the photonic crystal multilayer film structure on the incident wave with a wavelength near a preset target wavelength, and cooperating with the top surface patterning structure, the reflected wave front can be controlled, and the vertical mirror reflection can be reduced. Based on the photonic crystal high-reflection multilayer film structure, by using the constructive interference effect and cooperating with the phase control pattern structure, the phase control reflected electromagnetic wave front can be controlled, so that the vertically reflected electromagnetic wave is deflected to other directions, the conversion from high mirror reflection to high scattering of 8-14 mu m infrared waves can be realized, and the mirror reflection is inhibited.

The application provides an anti-icing and drag-reducing stealth patch, a preparation method thereof and an aircraft, and relates to the field of stealth technology.The anti-icing and drag-reducing stealth patch comprises, from bottom to top, a substrate layer, a heating layer and a super-smooth drag-reducing layer, wherein the heating layer is composed of a glass fiber cloth layer connected to the substrate layer and a graphene layer distributed in an island-like network on the glass fiber cloth layer, the super-smooth drag-reducing layer is composed of a polydimethylsiloxane coating layer and silicon oil injected into the polydimethylsiloxane coating layer, and a plurality of drag-reducing micro-grooves are arranged on the super-smooth drag-reducing layer in an interval manner.The application can realize the functions of radar wave penetration, anti-icing and drag reduction, can be used in harsh environments, and can meet the use requirements of civil and military aircrafts.

The application discloses a carbon-based superstructure integrated with wave-absorbing stealth and electric heating deicing and a preparation method thereof, and belongs to the field of functional composite materials and aerospace stealth technology. The carbon-based superstructure comprises a substrate layer and a periodic array structure on the top surface of the substrate layer. The periodic array structure comprises a plurality of superstructure units. Each superstructure unit comprises a cylindrical dielectric layer and a circular-truncated-cone wave-absorbing layer which are alternately stacked from bottom to top, and the two are alternately stacked to form a multi-stage impedance gradient junction. The application combines machine learning to accurately optimize the geometric parameters of each layer in the superstructure unit, so that the superstructure realizes efficient wave absorption in a super-wide frequency range of 2-40 GHz (the bandwidth of the reflection loss lower than -20 dB is significantly widened), and still maintains excellent stealth performance under large-angle incidence (greater than 45 degrees). Meanwhile, the superstructure has efficient and rapid electric heating deicing capacity, and solves the problems that the traditional aviation materials are difficult to be compatible with stealth and deicing functions, and have poor large-angle stealth performance.

The invention provides a stretchable spiral fiber material with an infrared stealth function, and belongs to the technical field of infrared stealth. According to the invention, MXene / CA (cellulose acetate) fiber with a core-shell structure is prepared by using a coaxial wet spinning technology, and is wound on a round rod to endow the fiber with a spiral structure. Wherein the fiber has infrared stealth performance due to the high content of MXene in the shell layer, and the fiber has spiral setting capacity due to the high content of CA in the core layer. In the blending spinning process, a large number of hydroxyl groups of CA easily generate intramolecular hydrogen bonds and easily form an intermolecular hydrogen bond network with surface active groups of MXene, the spinnability of MXene and the stability and stretchability of the spiral fiber can be remarkably improved by means of introduction of CA, and the use performance of the spiral fiber is further improved. Meanwhile, cavities in the spiral fibers enable the material to have certain heat insulation performance. The stretchable spiral fiber material provided by the invention can show an excellent infrared shielding characteristic.

The invention discloses a method and device for measuring a complex scattering function of a radar target, and relates to the field of microwave stealth technology and active microwave remote sensing, and the method comprises the steps: constructing a generalized radar equation represented by a complex voltage for a radar detection target; according to the generalized radar equation, fitting to obtain a relation curve of the amplitude and the distance of the complex scattering function and a relation curve of the phase and the distance; performing low-pass filtering processing on the relation curve of the amplitude and the distance and the relation curve of the phase and the distance; and for the relation curve of the amplitude and the distance after filtering and the relation curve of the phase and the distance after filtering, obtaining the amplitude and the phase of the complex scattering function at the infinite far field by adopting a polynomial fitting and limit taking method. According to the invention, the method can directly and accurately measure the complex scattering function of any small to-be-measured target (including a standard device), and does not need an RCS standard device with a known standard value in the measurement process.

The application provides a multifunctional active wave absorber with reflection polarization conversion in a high frequency band, comprising a plurality of active wave absorber units arranged periodically, each active wave absorber unit comprising a top polarization converter, a loss layer, a switching layer and a bias circuit layer; the top polarization conversion layer comprises a double "C" type metal patch and a first dielectric layer; the loss layer comprises a plurality of symmetrical resistors, metal patches and a second dielectric layer; the switching layer comprises a plurality of symmetrical PIN diodes and metal patches; the bias circuit comprises a third dielectric layer, a metal microstrip line and a metallized via group. By controlling the on-off of the PIN diodes, the wave absorption-transmission-polarization conversion or wave absorption-reflection-polarization conversion function can be realized. The application can provide stable dual polarization characteristics, realize switching of the working state by controlling the on-off of the PIN diodes, effectively reduce the backscattering of a single station radar, has the characteristics of multifunction, dual polarization and the like, and has a wide application prospect in radar stealth technology.

The invention relates to designs and optimizations for reducing radar visibility of ball turrets used in military and civilian platforms. In particular, the invention focuses on innovative geometric designs and radar stealth technologies for reducing a radar cross section (RCS) based on the azimuth angles. The present invention aims to control the reflection of electromagnetic waves from target surfaces, so that the probability of radar detection in threat sectors is decreased.

The application relates to the field of ship infrared stealth technology and discloses a method and device for analyzing the infrared stealth performance of a ship power exhaust system, wherein the method comprises the following steps: according to a preset flow field calculation model, a chimney opening window geometric model of the ship power exhaust system is built; according to the chimney opening window geometric model, fluid simulation is carried out on the chimney part of the ship power exhaust system, and the corresponding relationship between the chimney opening window area and the average temperature of the chimney outlet is obtained; according to the average temperature of the chimney outlet corresponding to different chimney opening window areas, the infrared radiation brightness corresponding to different chimney opening window areas is calculated, and the corresponding relationship between the chimney opening window area and the infrared radiation brightness is obtained; and according to the corresponding relationship among the chimney opening window area, the average temperature of the chimney outlet and the infrared radiation brightness, the chimney opening window area corresponding to the maximum infrared stealth performance of the ship power exhaust system is determined.

This invention relates to a broadband angular domain RCS reduction structure based on the synergy of wave absorption and phase cancellation, belonging to the field of electromagnetic functional materials and structures. It is composed of several periodically distributed metamaterial units. Each metamaterial unit has a matching layer, an upper substrate layer, a copper pattern layer, a lower substrate layer, and an absorbing medium layer distributed sequentially from the incident wave irradiation direction. The copper pattern layer includes an octagonal frame cut around the perimeter and a cross structure located in the center of the octagonal frame. The octagonal frame and cross structure are of different sizes among the various metamaterial units. This invention has the advantages of breaking through the working bandwidth limitation of a single mechanism and significantly improving azimuth adaptability, providing a new solution for broadband large-angle stealth technology.

The invention discloses preparation and application of a flexible wearable material suitable for medium and low temperature infrared stealth and belongs to the technical field of wearable infrared stealth, the material is of a double-layer composite structure and comprises an upper layer low infrared emissivity composite film, a lower layer low infrared emissivity composite film and a lower layer low infrared emissivity composite film, the upper layer low infrared emissivity composite film is formed by compounding MXene nanosheets and waterborne polyurethane WPU, and the thickness of the upper layer low infrared emissivity composite film is 0.05-2 mm; the topological soft gel is a material with a porous structure inside, the thickness of the topological soft gel is 0.3-5 mm, and the cell size distribution of the topological soft gel is 150-250 [mu] m; wherein the upper-layer composite film is attached to the surface of the lower-layer topological soft gel in a coating manner; the flexible wearable material disclosed by the invention not only has relatively low infrared emissivity, but also has good heat insulation and heat preservation functions, and can meet the requirements of medium and low temperature infrared stealth in different indoor and outdoor scenes at night.