75results about How to "Increase reflection loss" patented technology

The invention discloses a double-shell-structure carbonyl iron powder composite wave-absorbing material and a preparation method thereof, wherein the composite wave-absorbing material is of a double shell layer core-shell structure, the core is carbonyl iron powder, the inner layer of the double-shell layer is an insulating layer, and the outer layer of the double-shell layer is a magnetic layer;the thickness of the insulating layer is 1 nm-1 [mu] m; and the thickness of the magnetic layer is 1nm-5 [mu] m; the preparation method comprises the following steps: coating the surface of the carbonyl iron powder with the insulating layer and coating the surface of a core-shell structure precursor by a chemical coprecipitation method. The surface of the carbonyl iron powder is coated with the double-shell layer by the chemical coprecipitation method. The impedance matching characteristic of the material is greatly improved, meanwhile, a large amount of nano-interface heterojunction is formedat the interfaces of the inner core and the double-shell layer, so that interface polarization is effectively induced, the scattering effect is formed for electron migration, and electromagnetic waveloss mechanisms such as multi-reflection absorption, strong ] ferromagnetic resonance and eddy current loss and the like of the material are greatly improved, so that the wave absorbing performance of the material is remarkably improved; the composite wave-absorbing material is simple in preparation method, is uniform and compact in coating and controllable in coating layer thickness and particlesize.

The invention discloses a method for preparing multilayer hollow metal microspheres for an electromagnetic wave absorbing material. The microspheres are prepared by a method of combining autocatalytic reduction reaction and chemical plating process. Inner-layer hollow Ni spheres are obtained by adopting the autocatalytic reduction reaction; and a single-layer or multilayer Co or Fe metal or Co1-xFex alloy film is coated on the surface of the Ni hollow spheres by chemical plating, and the thickness is adjustable. The obtained multilayer hollow microspheres have high magnetization intensity, and the density is less than 3.0g/cm<3>. The electromagnetic wave absorbing material meets the requirement of high-frequency electromagnetic wave absorption, and meanwhile has the characteristics of light weight and thin layer.

A transmission line with a bending portion is provided, which line comprises any one of a coplanar line, another coplanar waveguide line formed on the dielectric substrate under which a ground layer is provided and a coplanar strip line. A chamfered portion is provided on the outer angular portion of the bending portion of the signal wiring conductor and a triangular conductor is disposed to an inner angular portion thereof. Given that length of the chamfered portion is defined as a, and length of the wiring edge side of the triangular conductor is defined as b and width of the signal wiring conductor is defined as c, it is arranged such that a is greater than b+c×square root of 2. Thereby, a transmission line or an optical module of smaller reflection loss at the bending portion thereof and of improved high-frequency characteristics is provided.

The invention relates to a novel broadband coaxial waveguide orthomode coupler based on a turnstile structure. The novel broadband coaxial waveguide orthomode coupler comprises the turnstile structure, two power synthesizers or distributors or two impedance transformers, wherein the turnstile structure comprises a coaxial waveguide, an impedance matching structure and a coupling rectangular waveguide; each of the power synthesizers or distributors comprises a bent waveguide and a three-port cavity structure; and the impedance transformers are fifth-order rectangular waveguide step gradual-changing structures. According to the novel broadband coaxial waveguide orthomode coupler, the orthogonalp polar signal coupling problem in a coaxial feed waveguide in a multi-frequency satellite communication antenna system, and the broadband working characteristic problem of the coaxial waveguide orthomode coupler are solved, and the orthogonal signal coupling function requirements within dual receiving and sending frequency bands of a Ku-frequency-band satellite communication feed source antenna can be satisfied.

A zigzag coplanar waveguide-structured millimeter-wave MEMS phaser relates to a minimized millimeter-wave phaser, which resolves the problem that the prior MEMS phasers have small single-bridge phase shift and low phase precision. The invention comprises a coplanar waveguide and n metal bridges, the coplanar waveguide is composed of a base plate, a signal wire and two ground wires, the signal wire is fixed on the middle of the upper surface of the base plate, the ground wires are fixed on the two sides of the signal wire at intervals, the metal bridges periodically cross the base body of the coplanar waveguide, and the two ends of each metal bridge are respectively fixed on the ground wires on the coplanar waveguide; the invention also comprises n dielectric substrates, the two sides of the signal wire right under each metal bridge have symmetric zigzag concaving inwards, the dielectric substrates are fixed on the surface of the signal wire corresponding to the zigzag, and the dielectric constant of the dielectric substrates is 2-20 and the thickness t is 0.1Mu m-5Mum. The invention can be widely applied to a radio frequency communication system and a small-sized phased array radar, a phased array antenna system and so on.

The invention discloses BaTiO3/Co3O4 oxide complex-phase millimeter wave absorbing powder having multi-stage microstructure distribution and a preparation method. The complex-phase millimeter wave absorbing powder having multi-stage microstructure distribution is obtained by firstly preparing precursor powder through a sol-gel method, performing ball milling, then executing the multi-step regulation and control heat treatment process including decomposition, control nucleation, dense growth and the like in a high temperature furnace to obtain a complex-phase sintering sample and finally controlling ball milling. The electric and magnetic parameter resonance phenomena of the BaTiO3/Co3O4 oxide complex-phase millimeter wave absorbing powder under the millimeter wave characteristic frequencybands are successively achieved, the frequency of their wave absorbing frequency bands is 35GHz in a typical millimeter wave window, the frequency band width can be up to 5 GHz, an RL value reaches -40 dB. The preparation method of the complex-phase millimeter wave absorbing powder is simple in preparation process and low in cost, and can be widely used in the fields of millimeter wave electromagnetic shielding and invisibility.

The invention discloses a reduced graphene oxide/nickel oxide composite wave absorbing material. Nickel oxide nanoparticles with the particle size of 1-100nm are uniformly distributed on a graphene nanosheet. The composite wave absorbing material has superior microwave absorbing performances: the lowest optimum reflection loss is -55.5dB, and the highest absorption frequency band below -10dB is 6.7GHz. The composite wave absorbing material has a light weight, and can meet the characteristics of light weight and high strength of wave absorbing materials. The invention discloses a preparation method of the composite wave absorbing material. The preparation method comprises the following steps: dissolving nickel acetate in a graphene oxide solution, freeze-drying, and carrying out high temperature pyrolysis on the obtained freeze-dried sample in argon atmosphere to prepare the wave absorbing material. The preparation method has the advantages of simplicity, environmental protection and low cost.

Microwave switching method and apparatus useful in high frequency operations (~40 GHz) includes structure and/or steps for providing a plurality of parallel upper switch cards, each having at least one input and a plurality of outputs; and a plurality of parallel lower switch cards, each having a plurality of inputs and at least one output. The plurality of lower switch cards is disposed perpendicular to the plurality of upper switch cards. A connector board is disposed between the edges of the plurality of upper and lower switch cards, the connector board having a two-dimensional planar array of electrical-coupling terminals for electrically coupling the plurality of upper switch cards outputs to the plurality of lower switch card inputs. Preferably, the electrical-coupling terminals comprise solder bumps disposed at either end of metallized via holes through the board, the solder bumps couple to wells disposed at the edges of the upper and lower switch cards.

The invention relates to a wet-ground copper slag cement-based electromagnetic shielding composite material and a preparation method thereof. The preparation method comprises the following steps: adding water into copper slag for wet grinding, and obtaining wet-ground copper slag slurry for standby application; immersing the recycled carbon fibers into water, uniformly dispersing the recycled carbon fibers into the water, adding a dispersing agent, uniformly stirring, adding a defoaming agent, and carrying out ultrasonic treatment for a period of time to obtain a carbon fiber dispersion liquidfor later use; taking and mixing portland cement, the wet-ground copper slag slurry, waste tire rubber powder, the carbon fiber dispersion liquid and the water reducing agent solution, and evenly mixing to obtain the wet-ground copper slag-based cement-based electromagnetic shielding composite material. According to the invention, industrial wastes such as copper slag, recycled carbon fibers andwaste tires are utilized, so that the mechanical property and electromagnetic shielding property of the cement-based composite material are effectively improved, and the cost is reduced while the green and environment-friendly scientific development concept is realized.

The invention relates to a preparation method of graphene composite silicon-carbon-nitrogen precursor ceramics, wherein the preparation method includes the following steps: (1) stirring polysilazane (PSZ) and graphene evenly in an N2 atmosphere to obtain a mixed solution; (2) rising the temperature of the mixed solution obtained by the step (1) with the heating rate of 3-5 DEG C/min from room temperature to 300-800 DEG C, and solidifying for 1-8 h; (3) carrying out crushing ball milling of the material solidified in the step (2) in a vibrating ball mill, and allowing the powder to pass througha 100-200 mesh sieve; (4) carrying out press molding of the powder obtained in the step (3) under the pressure of 5 MPa-15 MPa, carrying out cold isostatic pressing, and under the pressure of 150-250MPa, maintaining the pressure for 200-400 s to obtain a green body; and (5) carrying out heat treatment of the green body obtained in the step (4) under N2 atmosphere protection at the temperature of1000 DEG C-1300 DEG C, carrying out heat preservation for 2 h-6 h, and thus obtaining the product. The graphene material is introduced in the preparation process of a precursor, a real part and a virtual part of the relative complex dielectric constant of the ceramic material obtained by heat treatment are increased, the loss factor is increased and the reflection loss of the material is improved.

The invention relates to an optical fiber insert core and a preparation method thereof as well as a quick joint. The optical fiber insert core comprises a cylindrical insert core body, and the front end of the cylindrical insert core body is in a frustum shape. The optical fiber insert core is characterized in that the cylindrical insert core body is internally provided with an insert core hole and a tail taper hole; the insert core hole and the tail taper hole are centrally arranged front and back along the horizontal axial direction of the cylindrical insert core body; the cross section of the insert core hole is in a rectangular shape or a triangular shape or an elliptical shape or an ovoid shape, or the cross section of the insert core hole is in a circular shape, and the circular inner wall of the insert core hole is provided with at least one side groove along the horizontal axial direction of the cylindrical insert core body; the front end of the side groove penetrates through the front end surface of the cylindrical insert core body, and the rear end of the side groove is communicated with the front end of the tail taper hole. In the invention, the optical fiber insert core substitutes the insert core as an optical fiber coupling butt-joint collimating device for a glass capillary tube, thereby manufacturing an optical fiber butt-joint low-loss mechanical type wiring terminal and manufacturing a series of high-quality (low-insertion loss and high-reflection loss) field assembled quick joints by adopting an optical fiber embedding method.

An aircraft window includes: a window body including window panels, and an electromagnetic shield layer laminated on the window panels; a window frame that is made of a conductive material, and that surrounds the window body; a rubber-based gasket provided with conductivity, the gasket being at least partially held between the window body and the window frame; and a conductive layer that is located between the window body and the gasket, and that brings the electromagnetic shield layer and the gasket into conduction with each other. The window frame includes a holding section that holds the window body via the gasket from an airframe outer side. The conductive layer extends to a portion of the window body facing the holding section.

The invention discloses a design method for an EMI filter network with an impedance mismatching network. The EMI filter network with the impedance mismatching network comprises two parts of the mismatching network and an EMI filter; the EMI filter consists of an inductor L and a capacitor C; the mismatching network comprises an L-type mismatching network and a C-type mismatching network; the L-type mismatching network consists of a resistor RP and an inductor LP which are parallelly connected; the C-type mismatching network consists of a resistor RS and a capacitor CS which are serially connected; the L-type mismatching network is serially connected with the high impedance end of the EMI filter; the C-type mismatching network is parallelly connected with the low impedance end of the EMI filter; and the attenuation of the EMI noise by the EMI filter network is divided to two parts of the insertion loss brought by own EMI filter and the reflection loss after the EMI filter is connected to the mismatching network. High frequency impedance of the noise source and the high frequency impedance of the filter input port after connecting the mismatching network are located in the serious mismatching state, the larger reflection loss is generated to the EMI signal, and the EMI signal from the source end is effectively blocked to be transmitted into other electronic devices.

The invention discloses a lightweight composite wave-absorbing material and a preparation method thereof. The lightweight composite wave-absorbing material comprises magnetic powder and a lightweightmatrix, the lightweight matrix is formed by compounding microspheres with a hollow structure and a binder, and the magnetic powder is dispersed among the microspheres. The preparation method comprisesthe following steps: (1) preparing a lightweight matrix solution, namely uniformly mixing and stirring a solvent and a binder until the solvent and the binder are completely dispersed, and then adding microspheres; uniformly stirring and dispersing the binder and the microspheres in a solvent to form a light matrix solution; and (2) preparing the light composite wave-absorbing material: adding magnetic powder into the lightweight matrix solution obtained in the step (1), stirring to uniformly disperse the magnetic powder, and curing to remove the solvent to obtain the lightweight composite wave-absorbing material.

The invention relates to a magnetoelectric co-loss wave-absorbing agent derived from magnetic metal MOF and a preparation method. The magnetoelectric co-loss wave-absorbing agent is a composite material of a metal oxide derived from magnetic metal MOF and reduced graphene oxide, and is prepared by the following steps: mixing a metal salt with an organic complex, adding a graphene oxide aqueous solution, transferring the mixture into a container, performing reacting to obtain a compound of a precursor mono (bis, tri) metal MOF and rGO, carrying out heat treatment in a tubular furnace under the protection of gas, performing collecting, mixing with paraffin according to a ratio to prepare an annular piece, and finally determining the electromagnetic wave absorption performance of the sample. According to the method, the microstructure of a substance is possibly changed, the effective absorption bandwidth of the material is widened, and the material has higher reflection loss under the condition of lower thickness. The prepared composite wave-absorbing agent is uniform in particle size, complete in morphology and good in crystallinity.

A thin film solar cell includes a protection layer, a substrate and a photovoltaic conversion structure having a stack of one or several of non-planar light absorption layers, a first conductive layer being light transmissive and a second conductive layer being at least partially transparent or totally reflective. When the second conductive layer is totally reflective, it reflects the sunlight to the adjacent part of the thin film solar cell, proceeding another photovoltaic conversion and generating electric power again. If the non-planar light absorption layer is sloped enough, there will be several photovoltaic conversions produced by the same incident sunlight. More power will be generated and the efficiency of conversion is increased. If the second conductive layer is at least partially transparent, the incident light will be reflected less. However, the structure will provide several opportunities of photovoltaic conversions for the light with larger incident angle.

The invention provides a carbon nanotube-aluminum nitride wave-absorbing agent, a preparation method thereof, a carbon nanotube-aluminum nitride composite wave-absorbing material and an application ofthe carbon nanotube-aluminum nitride composite wave-absorbing material, and belongs to the technical field of wave-absorbing materials. The carbon nanotube-aluminum nitride wave-absorbing agent provided by the invention comprises a carbon nanotube and aluminum nitride; the surface of the carbon nanotube is coated with the aluminum nitride; the length of the carbon nanotube is 2-10 [mu]m; and themass of the carbon nanotube is 1-10% of the total mass of the carbon nanotube-aluminum nitride wave-absorbing agent. The aluminum nitride adopted by the invention has good thermal shock resistance, dielectric property and molten metal corrosion resistance; the carbon nanotube has the excellent characteristics of large specific surface area, high aspect ratio, excellent mechanical strength, outstanding dielectric property and the like; and functional groups or chemical bonds on the surface of the carbon nanotube are substituted or combined with chemical bonds in aluminum nitride, so that the dispersity of the carbon nanotube in the carbon nanotube-aluminum nitride wave-absorbing agent is improved, and the wave-absorbing performance of the carbon nanotube-aluminum nitride wave-absorbing agent is excellent.

The invention discloses a multilayer light-weight broadband electromagnetic wave absorbing material based on a metal-organic framework compound. The material is prepared by the following steps: by using hydrothermally synthesized copper 1,3,5-benzenetricarboxylic acid as a substrate, adding ammonium molybdate as a catalyst, performing high-temperature carbonization, and performing washing to finally obtain the multilayer porous carbon structure with rich mesopores and macropores. The method provided by the invention has a simple production process, the synthesized multilayer porous carbon material has the advantages of a low density, a large coverage bandwidth, high reflection loss and the like, and the method has good reference significance for preparing light-weight broadband electromagnetic wave absorption materials.

The invention relates to an electromagnetic shielding cement-based composite material prepared from wet-ground titanium slag and a preparation method of the electromagnetic shielding cement-based composite material. The cement-based electromagnetic shielding composite material prepared from the wet-ground titanium slag is prepared from the wet-ground titanium slag, recycled carbon fibers, a waterreducing agent, water, a dispersing agent, a defoaming agent and Portland cement. The material has the advantages of simple production process, short production period, relatively low cost and good electromagnetic shielding performance, solves the problem of accumulation pollution of industrial wastes such as blast furnace titanium slag and recycled carbon fibers, and is relatively high in comprehensive benefits.

The invention relates to a signal mixer used in coaxial broad band system of CATV broad band dual-network EPON+EOC. The multi-path signal mixer technical solution uses a mix technical solution that internet signal with one path to multi-path and RFTV signal are mixed, namely, one path IP DATA signal is divided into multi-path pre-mix signal that is mixed with corresponding RFTV signal, at the same time, a bypass over-current circuit is set in parallel on RFTV signal high pass filter. The whole EPON+EOC system structure can be simplified efficiently, assistant power supply does not needed for EOC amplifier, the system structure is simplified, system cost is reduced, and the mixer has technical advantages in low insertion loss, good frequency response and high reflecting loss or the like.