122results about How to "Improved Impedance Matching Characteristics" patented technology

The invention provides an ultra-wideband antenna. The ultra-wideband antenna comprises a dielectric substrate, wherein a radiation unit, a feeding structure and a ground plane are printed on the dielectric substrate; the radiation unit is a forked chip; the feeding structure is a coplanar waveguide feeding structure; and the ground plane is a coplanar waveguide ground plane. The ultra-wideband antenna has a coplanar waveguide structure, so that a single planar printed antenna structure can be realized; the ultra-wideband antenna can be easily integrated with a microwave integrated circuit; the coplanar waveguide ground plane can serve as the ground plane of the whole antenna, and particularly for the coplanar waveguide structure with a wideband slot structure, wideband work can be realized, and the electromagnetic interference of outside on the antenna can be effectively avoided; and wideband impedance bandwidth can be easily realized, and the efficiency of the antenna is improved, so that higher antenna gain can be achieved.

The invention provides wave-absorbing paper and a preparation method and application thereof. The wave absorbing paper contains 0.1-95 wt% of a fiber wave-absorbing agent and 5-99.9 wt% of wave-transparent fiber. The fiber wave-absorbing agent and wave-transparent fiber are mixed and prepared into the wave-absorbing paper by a papermaking process; and then the wave-absorbing paper as a lattice wall material is prepared into a wave-absorbing core sandwich; and then the wave-absorbing core sandwiches prepared from wave-absorbing paper with different fiber wave-absorbing agent content are separated by wave-permeable layers; and finally the entire structure is impregnated and cured to obtain the wave-absorbing material. The wave-absorbing material of the invention has the advantages of high wave-absorbing efficiency, stable wave-absorbing property, wide absorption band, and light weight and high strength.

The invention discloses an MXene-based flexible polyvinyl alcohol electromagnetic shielding composite film and a preparation method thereof, and belongs to the technical field of electromagnetic shielding materials. The invention relates to an MXene-based flexible polyvinyl alcohol electromagnetic shielding composite film and a preparation method thereof. The preparation method comprises the following steps of: etching an MAX phase with hydrofluoric acid to obtain layered MXene, then intercalating the MXene and graphene to obtain an MXene/Graphene compound, loading magnetic nanoparticles Fe3O4 on the MXene/Graphene to obtain a Fe3O4@MXene/Graphene ternary composite material, and finally dissolving the Fe3O4@MXene/Graphene ternary composite material and polyvinyl alcohol in deionized water and drying to obtain the polyvinyl alcohol composite film. The obtained polyvinyl alcohol film has very good flexibility and has good compatibility with a composite filler, and the electromagnetic shielding effectiveness in the X wave band can reach 38-52 dB. Layered MXene and graphene with good conductivity are beneficial to multi-reflection attenuation of electromagnetic waves, the impedance matching characteristic is optimized through combination with the magnetic particles Fe3O4, and attenuation of the electromagnetic waves is facilitated.

The invention provides a W-band broadband mixer, belonging to the technical field of millimeter wave devices. Based on the basic structure of the existing mixers, the invention adopts some innovative structural features for effectively expanding the frequency conversion band width of a mixer in the existing range of machining accuracy, reducing frequency conversion loss and enlarging the isolation among ports. The innovative structural features comprises: (1) a local oscillation signal energy coupling structure adopts a mutually staggered but non-overlapping asymmetric coupling structure; (2)an intermediate frequency filter adopts a low-pass filter composed of three split ring resonance units different in size and split directions in cascade connection; (3) an intermediate frequency end adopts a minisize rectangular cavity shield; and (4) matching gaps, reflecting metal sheets and the like are additionally arranged at a local oscillation end and a radio-frequency end.

The invention relates to the technical field of microwave absorption, in particular to a graphene-based ternary composite wave-absorbing material and a preparation method thereof. The preparation method comprises the steps of firstly, preparing silicon dioxide-coated carbonyl iron core-shell composite particles by using a sol-gel method, then preparing graphite oxide by using an improved Hummers method, evenly dispersing the graphite oxide into dispersion liquid of the silicon dioxide-coated carbonyl iron core-shell composite particles, and finally, using an ultrasonic reduction method to enable graphite oxide to be reduced into graphene so as to prepare the graphene-based ternary composite wave-absorbing material. The preparation method provided by the invention is simple and efficient; the prepared composite wave-absorbing material is more excellent in wave absorbing performance, high in wave absorbing strength, wide in wave absorbing bandwidth and smaller in density compared with a pure carbonyl iron binary composite wave-absorbing material and a pure graphene and carbonyl iron or graphene binary composite wave-absorbing material; the graphene-based ternary composite wave-absorbing material also has regulation performance, and can realize strong wave absorption under different frequencies by adjusting the thickness of a coating layer SiO2, the mass ratio of graphene to the coated core-shell composite particles and the thickness of the ternary composite material.

The invention discloses a novel miniaturized Vivaldi antenna, which is a novel Vivaldi antenna with a center frequency of 5.4GHz, a standing wave ratio of less than 2, an impedance bandwidth of 4GHz, a gain of 6.55dB, and a cross polarization ratio of -24.59dB. , the antenna also has the characteristics of small size, simple feeding, and high radiation efficiency, and can be suitable for civil wireless communication, wireless local area network (RLAN), fixed wireless access system (FWA), WiMAX and IEEE 802.11a wireless network, with Good application prospects, worth promoting.

The invention discloses a design method of a miniaturization label buckling antenna of a tire embedded radio frequency identification device (RFID). The design method comprises the following steps of determining geometric dimension of bending units and input impedance of a label chip; determining quantity of the bending units in the horizontal direction; determining quantity of the bending units in the vertical direction; adjusting width of a meander line to enable antenna gain to be maximum; and increasing feed ends and adjusting loop inductance to enable the antenna impedance to be in conjugate match with the chip impedance. The design method is simple, effective and convenient to design, has good impedance matching characters, and enables the miniaturization label buckling antenna to be maximum in radiation gain and low in cost. Simultaneously, the design method can be applied to RFID application fields of communication, industrial control, equipment manufacturing, intelligent agriculture, food safety and the like.

A broadband double circularly polarized end-fire array antenna based on a gap waveguide comprises an upper metal cover plate layer, a gap waveguide layer and a lower metal cover plate layer which aresuccessively stacked from top to bottom, wherein the gap waveguide layer is combined with the upper metal cover plate layer to form a upper gap waveguide structure, and is combined with the lower metal cover plate layer to form a lower gap waveguide structure; the upper and lower gap waveguide structure are fed through a first input port and a second input port respectively; the gap waveguide layer includes a metal separating plate, and metal ridges and a plurality of metal pins which are arranged on the front and back sides of the separating plate; each metal ridge includes a ridge gap waveguide T-type power divider and a three-stage stepped transition section transitioning from the ridge gap waveguide to a slot gap waveguide; the terminal of the metal separating plate is set as a separating plate circular polarizer; an antenna radiation structure is composed of a plurality of separating plate circular polarizers arranged in a matrix. The broadband double circularly polarized end-on-fire array antenna satisfies the characteristics of a wide frequency band, easy integration, and different circular polarization directions.

The present invention provides a microstrip slot shaped beam antenna of series fed by step-impedance line, composed of a microstrip dielectric slab which two sides are covered by metal, one side of the microstrip dielectric slab serving as a grounding plate is etched more than three identical gap radiation units which are arranged by same distance, the other side is provided with a microstrip line composed of the alternatively serial connection of two microstrip lines having different characteristic impedances, the impedance ratio of the two different characteristic impedances microstrip lines is more than 1.6; the relationship of the two microstrip lines is that: the other microstrip line is serially connected on one microstrip line between any two gap radiation units; the microstrip line protrudes from the first gap radiation unit to realize the short circuit feed of the first gap radiation unit. The antenna has a simple structure, light weight, easier design, lower cost, fit for the signal cover of the narrow and long region such as tunnel, expressway, long buildings.

The invention belongs to the design field of radio frequency integrated circuits, which in particular discloses a low-noise broadband amplifier with linearity compensation. The circuit comprises an active feedback unit, a current multiplexing transconductance unit, a direct-current feedback unit and a low-power supply voltage offset unit with the linearity compensation, wherein the direct-current feedback unit is used for stabilizing working points; the active feedback unit realizes broadband input impendence matching; the current multiplexing transconductance unit uses one transistor complementary with a main transconductance unit to serve as the other transconductance unit to improve gain under the condition of the same power consumption; a direct-current feedback loop is used for stabilizing the working points of the circuit; and the low-power supply voltage offset unit with the linearity compensation has the function of linearity compensation under the condition of providing offset to the circuit. According to the low-noise broadband amplifier, the low-noise amplifier with high linearity can be obtained by costing lower power consumption by the CMOS (Complementary Metal-Oxide-Semiconductor Transistor) technology.

The invention relates to a high-magnetic-conductivity wave-absorbing sheet and tape-casting slurry and a preparation method therefor. The tape-casting slurry for the high-magnetic-conductivity wave-absorbing sheet comprises the following ingredients in parts by weight: 80-85 parts of soft magnetic alloy powder, 8-12 parts of organic insulating elastic body, 3-5 parts of nonvolatile organic solvent, 2-3 parts of plasticizer and 1-3 parts of dispersing agent. The high-magnetic-conductivity wave-absorbing sheet is molded from the tape-casting slurry through a tape-casting process. The tape-casting slurry for the high-magnetic-conductivity wave-absorbing sheet has high wettability for the soft magnetic alloy powder; the prepared wave-absorbing sheet has high magnetic-conductivity, high resistivity and high flexibility; in addition, the preparation method is easy to control; and the prepared wave-absorbing sheet is high in yield and stable in performance.

The invention relates to a graphene composite wave absorbing material, a method for preparing the same and a coating agent prepared from the graphene composite wave absorbing material. The graphene composite wave absorbing material is made of zeolite and graphene. The graphene composite wave absorbing material, the method and the coating agent have the advantages that excellent wave absorbing performance of the graphene composite wave absorbing material made of microwave-treated reduced graphene oxide (m-rGO) and the zeolite (Na A) by means of composition is discovered, and the graphene composite wave absorbing material is an electric loss type wave absorbing material; the graphene composite wave absorbing material which is a novel full-inorganic wave absorbing material has characteristics of light weight, broad frequency bands and strong absorption, and accordingly the graphene composite wave absorbing material, the method and the coating agent have broad application prospects in future military and civil fields.

The invention relates to a preparation method of a marine environment-resistant magnetic wave-absorbing material. The preparation method of the wave-absorbing material comprises the following steps: respectively mixing the magnetic absorbent and the dielectric absorbent with the resin matrix and the diluent to obtain two wave-absorbing coatings, and alternately spraying the two coatings to obtainthe wave-absorbing coating; carrying out mechanical ball-milling crushing on the cured wave-absorbing coating to obtain magnetic absorbent powder with a microscopic multilayer structure, and carryingout mixing and compression molding on the magnetic absorbent powder and resin to obtain the magnetic wave-absorbing material with marine environment resistance. According to the preparation method, the magnetic absorbent and the dielectric absorbent form a uniform sandwich structure, the impedance matching characteristic is improved while the density of the wave-absorbing material is reduced, andthe corrosion resistance of the material is enhanced. The preparation method provided by the invention is simple and feasible, mature and stable in process, low in production cost and capable of realizing large-scale production.

The invention discloses a complementing ground holographically modulated surface dual-beam high-gain antenna, and mainly solves the problem of the influence of differences of floor structures on the radiation characteristic of the antenna. The antenna comprises a dielectric substrate, a holographic metal patch, a feed source monopole and a holographic complementing ground, wherein the holographic metal patch is printed on the upper surface of the dielectric substrate, and serves as a holographic surface structure of the antenna; the feed source monopole is arranged on the edge of the dielectric substrate, and is used for realizing antenna feeding; the holographic complementing ground is arranged on the lower surface of the dielectric substrate, and serves as an antenna ground; the holographic complementing ground and the holographic metal patch are mutual complementing structures, and the holographic complementing ground is used for forming near field coupling with the holographic metal patch under the excitation of the feed source monopole, thereby endowing the antenna with a dual-beam radiation characteristic and simultaneously enhancing the radiation gain of the antenna. According to the scheme, the holographic complementing ground forms near field coupling with the holographic metal patch under the excitation of the feed source monopole, thereby endowing the antenna with the dual-beam radiation characteristic and simultaneously enhancing the radiation gain of the antenna; the antenna has very high practical values and popularization values.

The invention provides a metasurface retroreflector microstructure design method based on topological optimization. The metasurface retroreflector microstructure design method comprises the following steps: establishing a metasurface multichannel reflector; dividing a design domain into a regular rectangular sub-grid array by using a two-dimensional periodic grid, and describing configurations of different microstructures by using difference combinations of metal layers in the two-dimensional sub-grid array; obtaining the length and the width of the supercell according to the incident angle and the specific frequency of the incident wave obliquely emitted to the multi-channel reflector; constructing a two-dimensional matrix, and enabling each array element in the two-dimensional matrix to represent attachment or deletion of a metal layer in the corresponding design domain sub-grid; modeling the scattering characteristics of a two-dimensional periodic array composed of supercells, and carrying out configuration optimization on a super-surface microstructure in the supercells by taking the maximum ratio of reflection power in the reverse direction of a required specific frequency at an incident angle to total reflection power in all directions as a design target. According to the super-surface retroreflector, the super cell is used as a design domain, and reasonable metal patch distribution is obtained so as to realize the super-surface retroreflector with the maximum retroreflection power ratio.

The invention discloses a broadband integrated balun and an antenna unit, the broadband integrated balun comprises a dielectric substrate, a microstrip line and a metal strip, the microstrip line is arranged on one side of the dielectric substrate, and the metal strip is arranged on the other side of the dielectric substrate; wherein the metal strips are a first metal strip and a second metal strip which are arranged in a coplanar mode, an isolation gap is formed between the first metal strip and the second metal strip, and tooth-shaped gaps are formed in one side, where the isolation gap is formed, of the first metal strip and one side, where the isolation gap is formed, of the second metal strip. The antenna unit disclosed by the invention can realize 2/3/4/5G frequency band (1.7-3.6 GHz) +/-45-degree dual-polarization stable electromagnetic radiation, and has the characteristics of wide working frequency band, high isolation degree and stable radiation pattern.

Enclosed is a zero-refraction microwave lens based on an electromagnetic double resonance structure. The zero-refraction microwave lens based on the electromagnetic double resonance structure is used for solving a problem of poor improvement effect of the existing zero-refraction lens with anisotropy to the antenna gain. N+1 secondary strip-type dielectric substrates and N primary strip-type dielectric substrates are alternately arranged in a mutually parallel manner at distances of d 1, d 2, d 1, d 2......d2. The primary strip-type dielectric substrates are etchingly made of the strip-type dielectric substrates with both sides coated with copper. A plurality of split ring resonators SRR with square openings are etched on both surfaces of each strip-type dielectric substrate and arranged along the longitudinal direction of each strip-type dielectric substrate. The shapes of the split ring resonators SRR with the square openings on one surface of each strip-type dielectric substrate are formed by rotating the split ring resonators SRR with the square openings on the other surface of each strip-type dielectric substrate around the center of the strip-type dielectric substrate. The secondary strip-type dielectric substrates 2 are etchingly made of the strip-type dielectric substrates with single sides coated with copper. The zero-refraction microwave lens based on the electromagnetic double resonance structure is used for assisting to increase the antenna gain.