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 an ultra wide band four-tape circularly polarized antenna which comprises a metal floor (1), a dielectric substrate (2), a radiation patch (3), a feed branch node (4), a matching branch node (5) and a micro strip line feed source (6), wherein the radiation patch (3), the feed branch node (4) and the matching branch node (5) are printed on the positive surface of the dielectric substrate (2) and are electrically connected with the micro strip line feed source (6) as well as are of a shaft symmetric shaft; a T type groove (7) is etched on the metal floor (1) which is used as a radiation reflection plate of the radiation patch (3); the center of the radiation patch (3) is etched with a polarized hole (8), the edge of the polarized hole (8) is provided with two mutually orthorhombic gaps (9) and (10), an intersection point of the two gaps is coincident with the center point of the polarized hole (8); and the micro strip line feed source (6) is placed on the edge of the dielectric substrate (2). The invention can realize that wide band four-tape circularly polarization characteristic with a wide polarization band, and can be applied to satellite communication.

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 discloses a pi-network-based millimeter wave frequency band receiver with an electrostatic discharge protection function, and belongs to the field of radio frequency and millimeter wave integrated circuit designing. The receiver comprises an electrostatic discharge (ESD) protection circuit consisting of back biased diodes, a low-noise amplifier (LNA) in a two-stage amplification structure, mixers of branch circuits I and Q, gain variable amplifiers of the branch circuits I and Q, a balun and an output ESD protection circuit consisting of the back biased diodes. Connection relationships among the circuits are that: the ESD protection circuit is connected in series with the LNA; the other end of the ESD protection circuit is an input end; the other end of the LNA is connected with the common input end of the two mixers of the branch circuits I and Q; the input end of the balun is a local oscillation (LO) end, and the output end of the balun is connected with the two local oscillation signal input ends of the mixer of the branch circuit I; the output ends of the mixers of the branch circuits I and Q are connected with the input ends of the gain variable amplifiers of the two branch circuits respectively; and the output ends of the gain variable amplifiers are connected to the final output end of the circuit after passing through the ESD protection circuit. By the invention, the electrostatic reliability of the circuit of the receiver can be ensured, and the overall performance of broadband input matching, high gain and low noise of the receiver can be improved.

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 discloses a high-efficiency five-order class F power amplifier. A circuit comprises an input fundamental wave matching network, a transistor, a parasitic parameter adjusting network, a class F higher harmonic matching network, an output fundamental wave matching network and a power supply decoupling bias network. According to the invention, the mutual independent accurate control ofthe fundamental wave load impedance to the fifth harmonic wave load impedance of the transistor is realized by adopting the class F higher harmonic wave matching network, and the compact network structure greatly saves the area occupied by the microstrip line circuit, thereby remarkably reducing the design cost of the circuit board. According to the high-efficiency five-order class F power amplifier, the harmonic energy loss of a transistor is reduced by utilizing a five-order class F amplification principle, the power amplification efficiency is improved, and each harmonic impedance is independently designed, so that each harmonic impedance control circuit does not influence each other, the later optimization debugging is not needed, and the design complexity is reduced.

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.

A radio frequency identification RFID anti-metal microstrip tag antenna disclosed by the invention is high in gain, low in cost and long in reading distance. According to the technical scheme, a radiation patch, a dielectric substrate and a metal floor form a resonant cavity, and the radiation patch covers a rectangular groove and is fixedly provided with a strip-shaped mounting seam of an RFID tag chip electrically connected with the radiation patch; a first strip-shaped gap is formed above a U-shaped groove, and a second strip-shaped gap and a third strip-shaped gap are formed in the left side and the right side of the U-shaped groove; and a protrusion is arranged at the bottom of the rectangular groove, one end of the strip-shaped mounting seam penetrates through the protrusion and is connected with the rectangular groove, the other end of the strip-shaped mounting seam penetrates through the bottom of the radiation patch, an edge field formed by gaps at the two ends of the U-shapedgroove generates radiation, and the metal floor, the radiation patch, a feeder line and a grounding line form an RFID anti-metal microstrip tag antenna. Based on the structure of the antenna and a slotting design, the performance of the tag is ensured under the condition that the thickness of the tag is reduced.

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.

The invention relates to a preparation method of a graphene-coated manganese dioxide composite wave-absorbing agent, belongs to the technical field of electromagnetic wave-absorbing materials, and solves the technical problems of weak binding force, poor composite interface performance and serious secondary agglomeration of heterogeneous materials, and the specific preparation process comprises the following steps: S1, weighing manganese sulfate and ammonium persulfate; s2, slowly adding the manganese sulfate into a graphene oxide aqueous solution at a constant speed, and carrying out magneticstirring at the same time, so as to prepare gel; s3, slowly adding the ammonium persulfate into the prepared gel at a constant speed, and magnetically stirring at the same time; s4, performing hydrothermal treatment on the mixed solution; and S5, separating a reaction product, washing the reaction product with deionized water until the reaction product is neutral, and freeze-drying the reaction product to obtain the graphene-coated manganese dioxide composite wave absorbing agent. The two components are tightly compounded in a chemical bond mode, the dielectric loss performance of the manganese dioxide to incident electromagnetic waves is brought into play, the multiple scattering performance of reduced graphene to the incident electromagnetic waves is combined, the preparation process issimple, and industrialization is easy to achieve.

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.

The invention discloses a boron and nitrogen co-doped graphene wave-absorbing material and a preparation method thereof; the attenuation factor of the wave-absorbing material is well matched with impedance characteristic parameters in a frequency band of 2-18 GHz, so that the material is guaranteed to have excellent electromagnetic attenuation capability. The invention also discloses an application of the wave-absorbing material in the fields of military and civil high-frequency electromagnetic compatibility and protection. The density of the wave-absorbing material is 0.3 kg / cm<3>, the maximum reflectivity and the effective coverage bandwidth of the material can be effectively improved within the frequency range of 2-18 GHz, and the wave-absorbing material is an electromagnetic compatibility and protection material capable of meeting the requirements of civil high-frequency electronic devices and military airships, cannonballs and other weaponry.

The invention discloses a high isolation Beidou array antenna based on an electromagnetic meta-material. The antenna includes four circularly polarized unit antennas and an electromagnetic meta-material isolation structure interposed among the unit antennas, wherein the four circularly polarized unit antennas and the electromagnetic metamaterial isolation structure are printed on the same dielectric substrate, each unit antenna includes a square patch and circular patches of different radii loaded at four corners, the electromagnetic meta-material isolation structure is composed of a metal microstrip, a medium, a metal through hole and a metal ground, the metal through hole passes through the dielectric substrate, and the metal microstrip is connected with the metal ground. The antenna isadvantaged in that the operating frequency band is 1256-1281MHz and completely covers a Beidou B3 frequency band; as the electromagnetic meta-material isolation structure has equivalent negative magnetic permeability, surface wave coupling among the unit antennas can be effectively suppressed, and thereby the array antenna has high isolation in the Beidou B3 frequency band.

The invention discloses a wave-absorbing material and a manufacturing method thereof. The wave-absorbing material includes: a core, an insulating layer located on the outer surface of the core, and a gap layer located between the core and the insulating layer; and the core and the insulating layer have different polarities or conductivities, so that when the wave-absorbing material is located in electromagnetic waves, the core, the insulating layer and the gap layer form a capacitance-like structure which is used for absorbing at least part of the electromagnetic waves. The core, the insulating layer and the gap layer of the wave-absorbing material form the capacitance-like structure to absorb the electromagnetic waves, so that the wave-absorbing performance of the wave-absorbing material is remarkably improved; and the impedance matching characteristic of the wave-absorbing material is improved through the insulating layer, and the wave-absorbing performance of the wave-absorbing material is further improved.

The invention relates to a preparation method of an Sm-doped modified quickly-quenched FeSiAl magnetic metal wave-absorbing material. The preparation method comprises the steps of smelting, quick quenching, and crushing and fine grinding. According to the smelting step, raw materials of rare earth Sm and FeSiAl are added into a vacuum smelting furnace so as to be smelt, so that an alloy master ingot can be obtained. According to the quick quenching step, the alloy master ingot is rapidly quenched in a vacuum rapid quenching furnace, so that an alloy quickly-quenched thin strip is obtained. According to the crushing and fine grinding step, the quickly-quenched thin strip is crushed on a high-speed crusher, and refined and crushed metal powder is subjected to high-energy ball milling on a high-energy ball mill, so that ball-milled powder can be obtained; and the powder which has been subjected to high-energy ball milling is subjected to vacuum drying, so to that the Sm-doped modified FeSiAl magnetic alloy wave-absorbing material can be obtained. The Sm-modified quickly-quenched FeAlSi magnetic metal wave-absorbing material prepared by the preparation method can be used for absorbingelectromagnetic waves in an S waveband and a C waveband of radar waves.

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.

A wide-angle wave absorbing structure design method based on additive manufacturing comprises the steps that a structure is divided into multiple layers according to the appearance and size of a stealth target, multiple layers of unit cell structures are selected, and the unit cell structures are periodically arrayed to form a multilayer structure; then multilayer oblique incidence impedance matching design is performed on the TE wave and the TM wave, an electromagnetic wave propagation path is designed and planned in the multilayer structure, and multilayer equivalent electromagnetic parameters are calculated; the design and control of the equivalent electromagnetic parameters are realized by controlling the variety and the proportion of an absorbent in a composite material and controlling the structural parameters of the unit cells; optimization is performed to obtain the types and proportions of the multilayer materials and the structural parameters of the unit cells; and modeling is performed, the reflection loss is calculated through simulation or the reflection loss is actually measured through 3D printing, and whether the design requirements are met or not is verified. According to the invention, the function of absorbing large electromagnetic waves with wide incident angles is realized, and the absorption angle can be actively designed, regulated and controlled.

The present invention discloses an eccentric-feeding metal-encapsulated portable terminal antenna and belongs to the microwave technical field. A metal-encapsulated portable terminal antenna is designed on a dielectric substrate; and the terminal antenna is used for covering some frequency bands of GSM, UMTS and LTE and exciting a plurality of high-order modes through an eccentric feeding mode to increase working bandwidth. The antenna of the invention is small in size, so that the realization of the compatibility and coexistence of the antenna with the multi-antenna system of a future wireless communication system can be benefitted. The antenna can be realized through the processing techniques of existing mobile terminal antennas, such as injection molding, flexography and three-dimensional printing and a bright application prospect.

The invention belongs to the field of electromagnetic wave absorbing materials, and discloses a wave-absorbing patch with a periodic structure and a preparation method thereof. The wave-absorbing patch with the periodic structure comprises a plurality of periodic units 3. Each periodic unit 3 comprises a unit 1 and a unit 2, wherein the unit 1 comprises the following components in percentage by weight: 10%-25% of a polymer binder, 60%-75% of Fe-Si-Al soft magnetic alloy magnetic powder, 15%-30% of carbonyl iron powder and less than or equal to 1% of auxiliary materials; and the unit 2 comprises the following components in percentage by weight: 30-60% of polymer binder, 35-65% of conductive carbon black, 5-15% of silicon dioxide and less than or equal to 2% of assistant. Compared with a traditional wave-absorbing magnetic sheet, the wave-absorbing patch provided by the invention has better electromagnetic wave absorption performance through unique periodic unit design and component andpreparation process design of each unit, and the wave-absorbing frequency of the patch is broadened.