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70 results about "Permittivity distribution" patented technology

Low-profile lens antenna capable of realizing wide-angle scanning

InactiveCN105742824AOvercome the disadvantage of not being able to conformal designLow profileAntennasDistribution characteristicBeam scanning
The invention relates to a low-profile lens antenna capable of realizing wide-angle scanning. The lens antenna comprises a lens and a feed source positioned on the focal plane of the lens; beam scanning and tracking can be realized by mechanical control on the feed source; the lens has an electromagnetic wave focusing function, and the appearance of the lens can be flat-plate-shaped or curved-surface-shaped, and conformal design with a carrier platform can be realized; the effective dielectric constant distribution characteristic of the lens is that the effective dielectric constants are decreased from the center to the edges along the horizontal and longitudinal directions; the regulation and control on the effective dielectric constants can be realized by changing the structure or dimensions of the metamaterial units; and the assembling and preparation of the lens at a low cost is realized by multiple metamaterial panels in a stacked manner. The low-profile lens antenna has the characteristics of broadband, high gain, low profile, easy conformal property and the like, and is particularly suitable for high-gain conformal vehicle-mounted or missile-borne platforms in the fields of communication measurement and control, and the like.
Owner:NO 54 INST OF CHINA ELECTRONICS SCI & TECH GRP

Electromagnetic inverse scattering imaging method based on compressed sensing

ActiveCN102955159AEffectively keep the edge outline clearKeep sharp edgesElectromagnetic wave reradiationObservation dataImaging technique
The invention discloses an electromagnetic inverse scattering imaging method based on compressed sensing and relates to a microwave imaging technology. The electromagnetic inverse scattering imaging method comprises the following steps of: step 1, microwave excitation and measurement stage, carrying out penetrating irradiation on a target by microwave outside the target and measuring a scattering back wave of the target so as to sense internal structure and material of the target; step 2, target molding stage, establishing a nonlinear observation model between dielectric constants and the scattering back wave of the target and establishing a representation model describing sparsity of the internal structure of the target; and step 3, calculating imaging stage, imaging distribution of the dielectric constants of the target by using a target model and a compressed sensing processing method, wherein imaging results are used as representations of the internal structure of the target as different dielectric constants correspond to different constituent materials of the target. Compared with the conventional microwave imaging method, the compressed sensing processing technology is utilized by the electromagnetic inverse scattering imaging method so that the back wave observation data amount is significantly reduced and the imaging definition of the internal structure of the target is significantly improved simultaneously.
Owner:INST OF ELECTRONICS CHINESE ACAD OF SCI

Electromagnetic imaging system and method employing oblique incident wave

The invention discloses an electromagnetic imaging system and method employing an oblique incident wave. A scatterer is fixed on a rotating platform, and the periphery of the scatterer is uniformly provided with a plurality of receiving antennas at intervals. All receiving antennas are connected to a microwave switching network, and the needed receiving antennas are selected to be connected for operation through the microwave switching network. The microwave switching network is connected with a vector network analyzer, and the vector network analyzer is connected with a transmitting antenna through a radio frequency power amplifier. The incident field data and the total field data after each rotation are obtained firstly, and then the subtraction of the incident field data and the total field data is carried out to obtain the scattering field data of each measurement. An imaging region is equally divided to obtain a Green function, and a target function is built. An optimization algorithm is employed for solving the minimum value of the target function, and the distribution of dielectric constants is obtained. The system and method solve a problem of shading and cross coupling of receiving and transmitting antennas in an electromagnetic imaging system employing normal incident waves. The receiving and transmitting antennas can be flexibly arranged, and the proper incident angles can be freely selected according to the actual conditions.
Owner:ZHEJIANG UNIV

Defect detection and positioning method of planar array electrical capacitance tomography based on partial fractal dimensions

InactiveCN107422002AImplement automatic taggingHigh defect location accuracyMaterial capacitanceAviationGraphics
The invention relates to a defect detection and positioning method of planar array electrical capacitance tomography based on partial fractal dimensions. The defect detection and positioning method comprises the following steps: S1, putting a sample to be detected on a planar electrode array sensor in parallel in an alignment manner and measuring a capacitance value at the moment; taking the capacitance value as a capacitance value of a measurement object field; S2, reconstructing an image: reconstructing a dielectric constant distribution image by utilizing an LBP (Local Binary Pattern) algorithm; S3, processing the image: extracting a color matrix corresponding to a defect color in a false-color image; S4, partitioning the reconstructed image into blocks and calculating a fractal dimension of each block; determining a threshold value according to a fractal dimension histogram of the blocks of the reconstructed image; S5, marking a square hole with the fractal dimension which is greater than the threshold value to obtain a final marking result. The invention provides an electrical capacitance tomography detection method based on a planar array electrode, aiming at defects of a sticking layer of a composite material structure for aviation; a fractal theory is applied to defect automatic positioning of the reconstructed image of the electrical capacitance tomography of the planar array electrode, so that the defects of the reconstructed image are automatically marked and the defect positioning precision is improved.
Owner:YANSHAN UNIV

Capacitive tomography image reconstruction method based on closed-loop control principle

The invention relates to a capacitive tomography image reconstruction method based on a closed-loop control principle. The method mainly comprises the following steps of firstly, obtaining N(N-1)/2 independent measurement values under an empty field condition and N(N-1)/2 independent measurement values under the condition that an object exists through measurement by utilizing a capacitive tomography imaging system, and establishing an N*N capacitive variation matrix by utilizing a difference between the two types of the independent measurement values; secondly, taking a Calderon algorithm as acontrolled object, solving a new capacitive variation matrix by utilizing dielectric constant distribution inversely derived by the algorithm to serve as a negative feedback, and correcting a deviation value of capacitive variation by adjusting parameters of a PID controller, thereby enabling a whole closed-loop to be converged; and finally, if the number of iterations reaches a preset number ofiterations, ending the iteration and outputting a reconstruction result, otherwise, continuing the iteration. According to the method, the closed-loop control principle is combined with the Calderon algorithm for the first time, so that an image reconstruction error can be effectively reduced and the image reconstruction quality is remarkably improved; and the method has important practical valuesand good application prospects in the field of electrical imaging.
Owner:BEIHANG UNIV

Optical conversion multi-beam conformal lens antenna

InactiveCN110212309AOmit correction stepsOptimization process that omits feedRadiating elements structural formsParallel-plate/lens fed arraysPunchingMicrostrip antenna array
The invention relates to an optical conversion multi-beam conformal lens antenna. The optical conversion multi-beam conformal lens antenna comprises four parts comprising a dielectric lens, a multi-beam Rotman lens, a cylindrical conformal microstrip antenna array and a conformal floor, wherein the dielectric lens covers the cylindrical conformal microstrip antenna array, the conformal microstripantenna array is placed on the conformal floor, and the multi-beam Rotman lens is used for feeding the cylindrical conformal microstrip antenna array. By covering the cylindrical conformal array withthe quasi-conformal optical conversion dielectric lens, the cylindrical conformal array is equivalent to a virtual space planar array, and the converted non-uniform dielectric constant distribution isachieved by a dielectric punching periodic structure; the multi-beam Rotman lens is a multi-beam feeding network of the antenna and comprises a dielectric substrate, a copper laying plane, an input port, an output port, a virtual port, a copper laying lens cavity and a transmission line, the copper laying plane is formed on a lower surface of the substrate, the copper laying lens cavity is formedin an upper surface of the substrate, and the transmission line is connected with the lens and the conformal array; and by the optical conversion multi-beam conformal lens, seven beams within a coverage range being (-45)-(+45) degrees can be formed.
Owner:XIDIAN UNIV

Novel metamaterial

The invention relates to a novel metamaterial which comprises at least one material plate layer. Each material plate layer comprises a substrate and artificial microstructures attached onto the substrate. The substrate is virtually divided into a plurality of substrate units arranged in array mode. A pair of artificial microstructures is attached onto each substrate unit. Each pair of artificial microstructures comprises a first artificial microstructure and a second artificial microstructure attached onto each substrate unit. The first artificial microstructures and the second artificial microstructures are of snowflake-shaped structures or of derived structures of the snowflake-shaped structures. Each snowflake-shaped structure comprises two I-shaped structures orthogonal with each other. Each I-shaped structure comprises a first metal line, a second metal line and a third metal line connecting the first metal line and the second metal line, wherein the first metal line and the second metal line are parallel to each other. The third metal lines of the two I-shaped structures intersect and are perpendicular to each other. The material has broadband high dielectric constant in a certain frequency band, has distribution of dielectric constants gradually increasing from zero in another frequency band and can meet requirements of a specific situation.
Owner:KUANG CHI INST OF ADVANCED TECH +1

High polymer bonding explosive density distribution detection method based on capacitive tomography

The invention discloses a high polymer bonding explosive density distribution detection method based on capacitive tomography. A capacitance value between parallel plates is measured through a parallel plate capacitance method, relative dielectric constants of PBX materials under different densities are obtained through calculation, and a PBX material density value and a dielectric constant modelare established; a capacitance tomography system is built, the capacitance value between array electrode pairs of a to-be-tested PBX test piece array are measured in sequence, and three-dimensional reconstruction is carried out on the relative dielectric constant distribution of the PBX materials according to the measured capacitance value and the sensitivity matrix between all the electrode pairs; and according to the relative dielectric constant of the PBX material-PBX material density model, the density distribution of the PBX test piece is obtained, and detection of the density distribution of the PBX test piece is realized. According to the method, the density distribution of the PBX test piece can be quantitatively detected, and the method has the advantages of no damage, high efficiency and large detection range/portability, and can be widely applied to detection of density distribution determination and density uniformity of PBX test pieces.
Owner:INST OF CHEM MATERIAL CHINA ACADEMY OF ENG PHYSICS
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