35 results about "Invisibility cloak" patented technology

An electromagnetic invisibility cloaking device with a broadened cloaking bandwidth and/or a tunable frequency of operation. The cloaking device includes an object (e.g., antenna) and a metasurface (301) that conforms to the surface design of the object. The metasurface includes an array of metal cells (302A, . . . , 302Y), where each of the metal cells includes a circuit element (304) (e.g., active, passive, negative impedance converter element). The array of metal cells may be represented as an array of metal square patches, a mesh grid, horizontal or vertical conductive strips, or any arbitrary combination of unit cell patterns, where each opening, or a subset of them, in such an array includes an embedded circuit element. By incorporating the circuit elements in the conformal metasurface, the cloaking bandwidth is broadened and the frequency of operation is actively controlled and tuned.

The invention discloses a self-adapting super-surface electromagnetic invisibility cloak system and working method thereof. The system comprises a resonance module, a detecting module, a deep learningmodule and a voltage controlling module, wherein the resonance module is used for seamlessly splicing into a stealth suit; the voltage chip module is used for providing a direct current bias voltagefor the resonance module; the detecting module is used for detecting incident wave information of an electromagnetic wave and environmental background information of an invisibility cloak; and the deep learning module is used for receiving information detected by the detecting module, calculating the bias voltage value required by a resonance unit, and controlling the voltage chip module to provide a corresponding direct current bias voltage. By means of the self-adapting super-surface electromagnetic stealth system, the internal parameters is actively adjusted according to different incidentwave information and environmental background information, so that the real-time stealth is achieved; the human interference and a large number of time-consuming and laborious full-wave numerical simulation are unnecessary; and the efficiency and the sensitive reaction speed are high. The self-adapting super-surface electromagnetic invisibility cloak can be widely applied to the microwave frequency band and in the scenes with high requirements for real-time performance.

The invention discloses an exponential mapping-based design method of a retro-reflective optical invisibility cloak. Firstly, a two-dimensional x-y plane coordinate system is established, and conformal mapping is carried out on coordinates in a range of which a radius is R2; a plane wave is emitted in parallel from an x-axial negative direction to an x-axial positive direction; linear mapping under polar coordinates is carried out on a second quadrant and a third quadrant of the coordinate system, where the invisibility cloak is located, to enable the radius range to be mapped to R1-R2 from 0-R2; a first quadrant of the coordinate system is mapped, and a fourth quadrant of the coordinate system is mapped; then a metric tensor of deformed space and a dielectric tensor and a permeability tensor of an impedance matching medium provided by transformation optics are calculated according to the impedance matching medium and equivalent relationships of space geometry; and finally, a Z component in the permeability tensor is normalized, and an artificial metamaterial is selected and used according to dielectric tensor distribution and permeability distribution to manufacture the optical invisibility cloak. The method solves problems of invisibility for objects and extraction of information of retro-reflection behind the objects.

The invention discloses a design method of a thin-shell-type acoustic superstructure in any curved surface shape. The design method is used for design of a thin-shell-type low-and-medium-frequency broadband sound insulation structure, design of a curved surface shell-shaped ultra-thin light sound absorption structure, design of an ultra-thin carpet-type acoustic invisibility cloak fitting the complex curved surface shape, and the like. According to the thin-shell-type sound insulation structure designed through the method, after the curvature radius is decreased to a certain range, a sound insulation index curve can break through the cut-off frequency limit between a stiffness control area and a damping control area, the sound insulation trough at the cut-off frequency is eliminated, and excellent low-frequency broadband sound insulation performance is achieved. By properly selecting the separation distance between double-layer shells, a double-layer shell structure can achieve bianisotropic perfect sound absorption; and in order to adjust phase compensation of the designed complex curved surface shape structure and achieve the function of arbitrary adjusting and control of a wavefront phase, the equiphase design method is adopted, and the curved surface carpet-type acoustic invisibility cloak completely fitting the complex structure surface morphology can be designed.

The invention discloses a hologram image principle-based one-dimensional visible light invisibility cloak, and belongs to the field of visible light invisible materials and apparatuses. The hologram image principle-based one-dimensional visible light invisibility cloak comprises an inner protection layer, a signal transmission layer, a front shooting layer and a back shooting layer which are arranged outside the inner protection layer, a front display layer arranged outside the front shooting layer, and a back display layer arranged outside the back shooting layer; the front shooting layer is used for shooting situation outside the front display layer and transmitting obtained images to the back display layer in real time; the back shooting layer is used for shooting situation outside the back display layer and transmitting obtained images to the front display layer in real time; and the front shooting layer is same to the back shooting layer in structure, and n 3D high speed cameras and a microprocessor are arranged in each of the front shooting layer and the back shooting layer in order to rapidly process n simultaneously shot pictures. The one-dimensional visible light invisibility cloak has a reasonable structure, and realizes invisibility in visible light in a one-dimensional spatial direction.

The invention provides an adjustable and controllable two-dimensional thermal invisibility cloak based on multiple annular graphene layers. The adjustable and controllable two-dimensional thermal invisibility cloak is formed in the manner that with the center of the x-y horizontal plane as the axis, prolongation of annular graphene layers is conducted layer by layer in the x-axis direction and the y-axis direction. All the layers can correspond to different thermal conductivity coefficients through control over the Fermi level distribution of graphene in the different annular layers, and then two-dimensional thermal conductivity distribution needed by thermal invisibility is obtained; then, after thermal flow winds around the cloak area, a temperature field recovers original distribution, and therefore the thermal invisibility function is achieved; and an object at the center of the thermal invisibility cloak is sheltered from external thermal flow disturbance, and external thermal flow distribution is not influenced. The real-time switching on/off performance of the thermal invisibility cloak is achieved through circular control over the Fermi level distribution of the each annular graphene layer, and therefore the defect that the two-dimensional thermal invisibility cloak cannot be circularly switched on or off is overcome.

The invention provides an adjustable and controllable three-dimensional thermal invisibility cloak based on multiple annular graphene layers. The adjustable and controllable three-dimensional thermal invisibility cloak is achieved through a surface covering shell layer composed of graphene. The surface covering shell layer is formed in the manner that the multiple graphene annular layers are stacked from bottom to top. All the layers can correspond to different thermal conductivity coefficients through control over the Fermi level distribution of graphene in the different annular layers, and then three-dimensional thermal conductivity distribution needed by thermal invisibility is obtained; and then, after thermal flow winds around the cloak area, a temperature field and an isotherm recover original distribution, and therefore the thermal invisibility function is achieved. Meanwhile, the real-time switching on/off performance of the thermal invisibility cloak is achieved through circular control over the Fermi level distribution of graphene in each annular layer, and therefore the defect that the thermal invisibility cloak cannot be circularly switched on or off is overcome.

The invention discloses a liquid crystal based broadband negative refractive index device with adjustable temperature, and further discloses a production method of the liquid crystal based broadband negative refractive index device with adjustable temperature, aiming to solve the technical problem than a conventional negative refractive index device has a narrow working frequency band. In the technical scheme of the invention, liquid crystal is injected into a liquid crystal injection cavity formed by copper clad plates and U-shaped press strips, thereby ensuring the complete contact of the liquid crystal and a sheet metal; by utilizing the characteristic that the effective dielectric constant of the crystal liquid is influenced by ambient temperature, the capacitance and working frequency band of the negative refractive index device can be regulated to the largest extent by regulating the ambient temperature, so that the working frequency band of the negative refractive index device can change greatly with temperature. and the largest adjustment extent is up to 6.8%. The negative refractive index device can be used in novel electronic devices such as a flat lens and an invisibility cloak.

The invention belongs to the technical field of thermodynamics, and particularly relates to a thermal invisible cloak for thermal radiation. The thermal invisible cloak is of a shell layer structure,and objects in a shell layer cannot be found by infrared detection outside the shell layer as if objects in the middle do not exist; according to the method, Rosseland diffusion is used for approximately processing the heat radiation problem, and the heat conduction part is still described by the traditional Fourier law. The thermal invisibility cloak is composed of a heat insulation layer and a compensation layer, and by designing the Rosseland average extinction coefficient and the heat conductivity of the compensation layer, the thermal invisibility effect under the room temperature condition and the high temperature condition can be achieved at the same time. Through theoretical analysis and finite element simulation verification, the method can be applied to the fields of thermal radiation protection and the like.

The invention provides a mixed wave-absorbing diffuse reflection metasurface based on a metal-graphene composite structure, and the metasurface is obtained by arranging two coding metasurface units according to an optimal coding sequence, and each coding metasurface unit comprises a substrate dielectric plate, an air layer and a bottom metal grounding plate which are arranged from top to bottom. A metal-graphene mixed distribution structure is printed on the upper surface of the substrate dielectric plate, the metal-graphene mixed distribution structure comprises a metal strip and a graphene thin-film resistor which are connected with each other, and the lengths of the metal strips of the two coding metasurface units are different. According to the mixed wave-absorbing diffuse reflection metasurface, reflected waves are equal in amplitude and reverse in phase, the reflected waves are subjected to cancellation interference to be diffused to a plurality of different directions, meanwhile, the reflected waves are absorbed, the RCS can be effectively reduced, the remarkable stealth effect is achieved, and the mixed wave-absorbing diffuse reflection metasurface has potential application in the fields of stealth cloaks, imaging, wavefront treatment and the like.