30results about How to "Improved Angular Stability" patented technology

The invention discloses an aperture multi-layer structure-based high-out-of-band rejection frequency selective material design method. The method includes the following steps that: (1) a frequency selective material is designed based on an aperture multi-layer structure, wherein the aperture multi-layer structure includes three layers of structures, namely, a top-layer patch, a bottom-layer patch and a middle coupled aperture layer; (2) an out-of-band transmission null characteristic is realized through constructing a design method of patch displacement of the top-layer patch and the bottom-layer patch, and the side band cut-off characteristic of the aperture multi-layer structure-based frequency selective material can be further improved; and (3) a unit interdigital technology is adopted to carry out miniaturization processing on the surface of the frequency selective material, so that the unit size of the surface of the frequency selective material can be decreased. With the method of the invention adopted, a high-order coupling characteristic is realized, and the side band cut-off performance of the frequency selective material can be improved; and the unit interdigital method is adopted, so that the unit size of the surface of the frequency selective material can be decreased, and angle stability under the incoming of electromagnetic waves can be improved; and the out-of-band rejection ability of the frequency selective material is stronger, and the pass-band edge rise performance and sharp drop performance of the frequency selective material are better.

The invention belongs to the technical field of antenna RCS (radar cross section) reduction, and particularly relates to a wide-angle RCS reduction metasurface based on a radar wave absorbing and scattering cancellation technology. The metasurface is characterized by comprising an upper dielectric substrate (2), a metal floor (1) and a lower dielectric substrate (3), radiation metal patches (11) are distributed on the upper surface of the upper dielectric substrate (2). microstrip feeder networks (10) are distributed on the lower surface of the lower dielectric substrate (3), and the upper dielectric substrate (2), the metal floor (1) and the lower dielectric substrate (3) are combined from top to bottom to form the wide-angle RCS reduction metasurface antenna array (4). Different from the conception of the prior art, the metasurface design is carried out in a mode of combining radar wave absorption and scattering cancellation technologies, and a good reduction effect can be realized in a wide-angle electromagnetic wave incidence range.

The invention discloses an electric system low frequency oscillation mode identification method based on correlation functions. The method includes the following steps that firstly, a section of an active power signal of a circuit having high observability for a low frequency oscillation mode under the circumstance that no large disturbance exists in an electric system is read and serves as a signal to be analyzed, and a sampling time interval Ts is determined; secondly, the read active power signal is preprocessed to obtain a corresponding power fluctuation signal; thirdly, a self-correlation function of the power fluctuation signal is solved, and a system free oscillation signal is obtained; fourthly, based on an extended Prony method, mode identification is carried out on the free oscillation signal to obtain a low frequency oscillation mode frequency and a damping ratio. The electric system low frequency oscillation mode identification method has the advantages that the method is only based on random response signals, operation is simple, the calculation amount is small, and identification accuracy is good.

The invention provides a wave-absorbing and wave-transmitting integrated frequency selective surface with an ultra-wide wave-transmitting band. According to the technical schemes, the wave-absorbing and wave-transmitting integrated frequency selective surface with the ultra-wide wave-transmitting band comprises FSS units which are periodically arranged, wherein all the FSS units are the same. EachFSS unit is of a structure comprising three layers, namely a first layer, a second layer and a third layer; the first layer comprises a dielectric plate (1); a metal patch (2) is arranged in the center of the upper surface of the dielectric plate (1); the metal patch (2) is of an N-arm square spiral structure; metal strips (3) are evenly distributed around the metal patch (2); each metal strip (3) is connected with the metal patch (2) through a resistor (4); the second layer is an air interlayer (5); and the third layer is a wave-transmitting layer (6). With the wave-absorbing and wave-transmitting integrated frequency selective surface with the ultra-wide wave-transmitting band of the invention adopted, an ultra-wideband, high-transmittance and high-angle stability wave-transmitting bandcan be realized, and a wave-absorbing characteristic can be generated outside the wave-transmitting band. In addition, the surface of the invention is simple in structure and easy to machine.

The invention relates to a 2.5D structure-based broadband wave-transparent frequency selective wave absorber, and solves the problem of narrow wave-transparent bandwidth of the existing frequency selective wave absorber. A loss layer, a lossless layer and an air layer form a frequency selective wave absorber, resonators which are periodically arranged are printed on the loss layer, and each resonator subunit rotates by 90 degrees, 180 degrees and 270 degrees along the center of a dielectric plate to be positioned by taking 0 degree as a reference direction; each subunit is internally providedwith short and long single-side fillets, a double-side fillet and a rectangular metal patch which are equal in width; and a 2.5D bent metal strip formed by the same bilateral rounded metal patches which are alternately distributed on the upper layer and the lower layer of the dielectric plate along a right-angle bending path is printed between the long unilateral rounded metal patch and the shortunilateral rounded metal patch. A right-angle bent metal strip structure is formed by utilizing a 2.5D structure, the wave-transparent bandwidth of the frequency selective wave absorber is broadened,the characteristics of wide wave-transparent band, bilateral wave absorption, polarization insensitivity, angle stability and small unit size are realized, and the 2.5D structure-based broadband wave-transparent frequency selective wave absorber is suitable for a broadband antenna system with stealth requirements.

The invention provides a 2.5D braided structure-based high-angular stability frequency selective surface and aims at improving the angular stability of the frequency selective surface. The 2.5D braided structure-based high-angular stability frequency selective surface comprises M*N passive resonance units, wherein each passive resonance unit comprises a dielectric slab, a first metal patch printedon the upper surface of the dielectric slab, a second metal patch printed on the lower surface of the dielectric slab, and metallized through holes; each first metal patch comprises six rotational symmetric first strip groups; each second metal patch comprises six rotational symmetric second strip groups; various strips in the second strip groups are located in gaps, in corresponding positions onthe lower surface, of various corresponding strips in the first strip groups; and the strips in the first metal patches and the second metal patches are connected through the corresponding metallizedthrough holes which penetrate through the dielectric slabs to form a 2.5D braided structure. According to the 2.5D braided structure-based high-angular stability frequency selective surface, good angular stability is achieved on the basis of miniaturization, and the 2.5D braided structure-based high-angular stability frequency selective surface can be applied to the aspects of communications andradars.

Disclosed is a white light top emission type OLED and a preparation method thereof. A substrate, a reflective anode, a hole injection layer, a hole transport layer, a double blue light luminous layer, a red light luminous layer, an electron transfer layer, an electron injection layer, a semitransparent cathode and an optical coupling output layer are sequentially evaporated from bottom to top. The preparation process comprises firstly cleaning the substrate, then performing evaporation in vacuum and cooling after the evaporation is finished. The preparation method of white light top emission type OLED effectively restrains multi-beam interference by means of the semitransparent cathode and the optical coupling output layer, thereby enhancing output of white light on the whole; enhances wide-angle interference of a blue light blue light waveband through a structural feature that the double blue light luminous layer is adjacent to the anode; utilizes the double blue light luminous layer of a heterojunction structure to control an exciton recombination region for increasing intensity of blue light as well as improving stability of chroma of a device; effectively improves the chroma and the stability of the white light top emission type OLED, thereby having potential application values.

The present invention provides an interdigital slot unit loaded with capacitance variable diodes and a reconfigurable reflection array antenna. The interdigital slot unit comprises a metal patch layer, a dielectric layer and a metal grounding layer which are sequentially stacked from top to bottom; a transverse slot, a first longitudinal slot, a third longitudinal slot and a second longitudinal slot are formed in the metal patch layer; the first longitudinal slot and the third longitudinal slot have the same length and are symmetrically distributed at two sides of the second longitudinal slot, and the second longitudinal slot has the other length; the first longitudinal slot, the second longitudinal slot and the third longitudinal slot are parallel to one another; the first transverse slot vertically passes through the center of the first longitudinal slot, the center of the second longitudinal slot and the center of the third longitudinal slot; two ends of the transverse slot are respectively loaded with two capacitance variable diodes; and the length setting of the three longitudinal slots satisfies a condition that the resonance frequency of the first longitudinal slot and the third longitudinal slot is 1.2 times to 1.5 times of the resonance frequency of the second longitudinal slot. The aperture efficiency of the reconfigurable reflection array antenna designed on the basis of the interdigital slot unit can reach 74%.

The invention discloses a dual polarization broadband external inhibition three-dimensional frequency selective surface. The frequency selective surface is of a three-dimensional periodic structure processed by a dielectric substrate, and comprises a square coaxial line waveguide and a parallel slab waveguide. The surface of the dielectric substrate is provided with metal patches, rectangular grooves are formed in two ends of each metal patch in the propagation direction of electromagnetic waves, and metal via holes in the dielectric substrate are connected to the metal patches on two sides. Adual mode resonator is formed by the parallel slab waveguide, a passband containing two transmission poles is generated, and due to the interaction between the two waveguides, a wide stop band containing two transmission zero points is generated near the passband. The frequency selective surface has low polarization sensitivity in a dual polarization operating mode, the frequency ranges of the passband and the stop band can be controlled by changing relevant physical parameters, dual polarization application is realized, and the frequency selective surface has high incident angle stability.

The invention discloses an atlantoaxial dislocation anterior anatomy template with an automatic reduction function. The atlantoaxial dislocation anterior anatomy template comprises an atlas part, an axis part and a connecting part. The atlas part is in an arc shape, and symmetrical screw holes are designed in the two sides of the atlas part. The axis part is located below the back of the atlas part and matched with the front structure of the body of the axis, five screw holes are designed in the axis part, four screw holes are symmetrically located in the two sides, and the other screw hole is located in the middle and is an oblong sliding screw hole. The atlas part and the axis part are connected through the connecting part. A screw slides in the sliding screw hole, so that the atlantoaxial dislocation reduction effect is achieved; through screw fixing, the atlantoaxial reduction purpose is achieved, the form of the template is completely matched with the anatomic form of the atlas and the axis, a higher degree of fit is achieved, and the template is attractive in appearance and good in reduction effect.

The invention discloses a wide-passband 3D frequency selection surface, and aims to improve the angle stability of the wide-passband 3D frequency selection surface. The wide-passband 3D frequency selection surface comprises mXn passive resonance units; each resonance unit comprises five layers of dielectric plates and four metal layers; each metal layer comprises four trapezoidal annular structures on the upper surface of the upper layer of the dielectric plate and the lower surface of the lower layer of the dielectric plate; the upper surface and the lower surface of the intermediate layer ofthe dielectric plate surround a square metal ring structure formed by the four edges of the dielectric plate, and two groups of 2X2 square ring structures in a square metal ring; the centers of the first group of the square ring structures are located at the four opposite corners of the dielectric plate; the centers of the second group of the ring structures are located on the center points of the center connecting lines of the adjacent first group of the ring structures; and the trapezoidal annular structures on the upper surface of the upper layer of the dielectric plate and the lower surface of the lower layer of the dielectric plate are correspondingly connected through lead wires. According to the structure, the angle stability is improved while edge steep drop and wide passband arerealized, so that the wide-passband 3D frequency selection surface can be applied to the situation of large incident angles and can be applied to the aspects of communication and radars.

The invention discloses a top emitting white light organic electroluminescent device and its preparation method, and belongs to the technical field of organic electroluminescence. The appliance comprises a top emitting blue light organic electroluminescent device and a micro-structure quantum dot lower converting film; the quantum dot material is used for absorbing a part of energy of the top emitting blue light appliance to generate photoluminescence; finally, two colors of lights are mixed to generate white light. By using the lower converting structure, the stability of spectrum along voltage and time is improved. By using the quantum dot as the lower converting material, the converting efficiency of the blue light pumping in the conversion process is improved, the lighting efficiency of the top emitting white light appliance is promoted. Through the embossing method, the microstructure array is introduced to the surface of the lower converting film of the quantum dot, the microstructure array can improve the light intake, scatter the light beam, and improve the angle stability of the spectrum.

The invention provides a polarization converter based on a multi-layer frequency selective surface, which is used to solve the problems of complex structure and high loss of the electrically adjustable polarization converter; on the upper surface of the first dielectric plate (2), the second dielectric The lower surface of the board (4) and the lower surface of the fourth dielectric board (6) are respectively printed with a patch array (1) composed of M×N corner-cutting square patches (11), and the first dielectric board ( 2) The lower surface and the lower surface of the third dielectric board (5) are printed with a grid array (3) consisting of M×N metal square rings (33); the four-layer dielectric board (2, 4, 5, 6) A stacked structure is sequentially formed from top to bottom. In the present invention, the angle between the polarization converter and the polarization direction of the incident ray polarized wave can be adjusted by rotation, so that the incident wave can be converted into left-handed circular polarization, right-handed circular polarization, or linear polarization. Wave characteristics. The invention can be applied to fields such as wireless communication and satellite communication.

The invention discloses a broadband frequency selective surface, and mainly solves the problems that the insertion loss is big and the angle stability is poor in the prior art. The broadband frequencyselective surface is formed by the stacking of multiple dielectric plates. Each dielectric plate is printed with M*N resonant units, and the resonant units are periodically distributed to form an array. Each resonant unit of the upper surface of the first dielectric plate (1) and the upper surface of the third dielectric plate (3) and the lower surface of the fourth dielectric plate (4) is a circular metal patch, and each resonant unit of the upper surface of the second dielectric plate (2) and the upper surface of the fourth dielectric plate (4) is a deformed cross-shaped metal patch, wherein the center of the deformed cross-shaped metal patch is circular. The broadband frequency selective surface can cover the band X, and has the characteristics of wide bandwidth, high transmissivity, out-band sharp drop and high cut-off, can improve the angle stability in the working band of 5GHZ-13GHZ, reduces the insertion loss within the working band, and can be used for radomes, communication and cloaking scenes.

The invention discloses an atlantoaxial dislocation anterior anatomy template with an automatic reduction function. The atlantoaxial dislocation anterior anatomy template comprises an atlas part, an axis part and a connecting part. The atlas part is in an arc shape, and symmetrical screw holes are designed in the two sides of the atlas part. The axis part is located below the back of the atlas part and matched with the front structure of the body of the axis, five screw holes are designed in the axis part, four screw holes are symmetrically located in the two sides, and the other screw hole is located in the middle and is an oblong sliding screw hole. The atlas part and the axis part are connected through the connecting part. A screw slides in the sliding screw hole, so that the atlantoaxial dislocation reduction effect is achieved; through screw fixing, the atlantoaxial reduction purpose is achieved, the form of the template is completely matched with the anatomic form of the atlas and the axis, a higher degree of fit is achieved, and the template is attractive in appearance and good in reduction effect.

The invention discloses a low-profile dual-band wave-absorbing surface applied to a vehicle-mounted radar test environment. The low-profile dual-band wave-absorbing surface comprises a dielectric substrate, an array printed on the front surface of the dielectric substrate and formed by periodically arranging resistive frequency selection units, and a metal floor printed on the back surface of the dielectric substrate, and the resistive frequency selection unit is composed of a resistive square ring and a resistive square patch, and the square patch is embedded in a hollow area of the square ring. According to the invention, effective absorption of electromagnetic waves can be realized in two vehicle-mounted radar frequency bands of 24GHz and 77GHz for omnidirectional angles, pitch angles within 30 degrees, TE polarized incident waves and TM polarized incident waves. Compared with the prior art, the low-profile dual-band wave-absorbing surface has the advantages of extremely low profile, light weight and simplicity and convenience in processing and mounting, can effectively eliminate the interference of stray electromagnetic waves when being applied to a vehicle-mounted radar test environment, can greatly reduce the occupied space of a test system, and has a very good engineering application prospect.

The invention concerns a bone plate system comprising: a bone fastening element comprising a shaft with a first thread, the fastening element further comprising a head with a second thread on its outer surface, the outer surface having a first hardness; and a bone plate having a second hardness which is smaller than the first hardness, the bone plate comprising a through hole for receiving the bone fastening element. The head is oxygen diffusion hardened.

The invention relates to a power angle stability improving method and system for an alternating current and direct current interconnected power system. The method comprises the steps of: collecting the power angle difference of a generator in the alternating current and direct current interconnected power system; determining a charging / discharging power reference value of the energy storage systemaccording to the power angle difference; determining the charging / discharging power of the energy storage system according to the charging / discharging power reference value; and controlling the energy storage system to perform charging / discharging based on the charging / discharging power of the energy storage system. The technical scheme provided by the invention aims at the power angle stabilitycharacteristic of the AC / DC interconnected power system, the feasibility that the energy storage technology rapidly consumes the unbalanced power of the AC-DC interconnected power system and improvesthe power angle stability of the AC-DC interconnected power system is analyzed, an energy storage controller capable of improving the power angle stability is designed, and finally the power angle stability of the AC-DC interconnected power system is improved based on the energy storage technology.

The invention belongs to the field of electromagnetic metamaterials, and relates to a low-RCS metasurface, in particular to an ultra-wideband RCS reduction metasurface based on mutual superposition of polarization conversion bandwidths, which is characterized by comprising an upper dielectric substrate (4), a lower dielectric substrate (5) and a metal reflecting plate (3) which are distributed at intervals from top to bottom, a low-frequency metasurface structure (1) of a lumped resistor is loaded on the upper surface of the upper-layer dielectric substrate (4), and a high-frequency metasurface structure (2) is arranged on the upper surface of the lower-layer dielectric substrate (5); and a low-frequency polarization conversion unit (111) in the low-frequency metasurface structure (1) and a high-frequency polarization conversion module (211) at the corresponding position in the high-frequency metasurface structure (2) form an overall polarization conversion unit (6), and coupling parameters are changed by adjusting the interval, shape and layout of low-frequency units and high-frequency units, so that the overall polarization conversion unit (6) obtains broadband polarization conversion. According to the invention, the bandwidth of RCS reduction is broadened, the angle stability of the metasurface is improved, and stable RCS reduction of more than 10dB in an ultra-wide frequency band can be realized under large-angle incidence of electromagnetic waves.

The invention belongs to the technical field of stealth and provides a high-performance frequency selection radar cover used for stealth of flight weapons in order to overcome the shortages of single-screen FSS (frequency selective surface) structural design in the prior art, and difficulty in achieving FSS engineering by bilateral dielectric load FSS and double-screen FSS due to complex structure and high processing difficulty. The radar cover comprises an original radar cover, a first splice dielectric layer, an ultralow dielectric constant dielectric layer, a second splice dielectric layer and a soft FSS film layer. The first splice dielectric layer, the ultralow dielectric constant dielectric layer, the second splice dielectric layer and the soft FSS film layer are molded and combined into an FSS lining from an outer layer to an inner layer, and an FSS lining layer is attached on an inner surface of the original radar cover. Due to the fact that selected cellular and foam media both belong to ultralight materials, weight of the frequency selection radar cover is not increased. The high-performance frequency selection radar cover is relatively simple in structure, process tolerance is large since design margin is large, and difficulty, cycle and cost of process are lowered.

The invention provides a broadband high-efficiency transmission type polarization converter. The converter is used for solving the problems of complex structure and high loss of an electrically tunable polarization converter. The upper surface of a first dielectric plate (2), the lower surface of a second dielectric plate (4) and the lower surface of a fourth dielectric plate (6) are respectively printed with a patch array (1) composed of M * N corner cut type square patches (11), and the lower surface of the first dielectric plate (2) and the lower surface of a third dielectric plate (5) are respectively printed with a grid array (3) composed of M * N metal square rings (33). And the four layers of dielectric plates (2, 4, 5 and 6) sequentially form a laminated structure from top to bottom. According to the invention, the incident wave can be converted into various transmission wave characteristics of left-hand circular polarization, right-hand circular polarization or linear polarization by rotating and adjusting the included angle between the polarization converter and the polarization direction of the incident linear polarization wave.

The invention proposes a fixing device for fixing the fracture ends of bones in a bone fracture comprising at least two tensioning elements (2a, 2b), each of which has a contoured body that is hollow when viewed from above, has a circumferential wall (4) and two face sided receiving sections (6a, 6b) lying opposite to each other, at least one clamping sleeve and at least two fixing means which can be position in the face sided receiving sections. The at least two tensioning elements (2a, 2b) are positioned in relation to each other in such a way that one receiving section (6a, 6b) of each tensioning element (2a, 2b) is aligned with the respective other receiving section and are penetrated by the clamping sleeve in such a way that both tensioning elements (2a, 2b) are coupled to each other. According to invention the clamping sleeve furthermore is an angle clamping sleeve (15) which is connected with the at least two tensioning elements (2a, 2b) in such a way that the latter lie in a predetermined angular position in relation to each other.

The invention discloses a bionic artificial atlanto-odontoid joint which comprises an atlas component, an axis component and a screw, wherein the atlas component comprises a middle cup-and-ball part and side wings; the cup-and-ball part comprises a ball cup part and a circular truncated cone part arranged at the lower end of the ball cup; two sides of the side wings are respectively provided with symmetric lock screw holes; the axis component is divided into an upper part and a lower part; the upper part comprises a top polyethylene ball head and a cylinder below the ball head; a multi-toothed structure is designed at the contact part of the bottom surface of the cylinder and a bone surface; the lower part is matched with the front structure of an axis body; three locking screw holes formed in a Chinese character 'pin' shape are formed in the lower part; hydroxyapatite coatings are designed at the contact parts of the joints and the bone surface. On the premise of keeping the rotation function of the atlas and axis, the limited lateral bending and flexion and extension functions of the atlas and axis are realized, the design depth of the cup-and-ball joint is large, and the dislocation risk is reduced, so that the atlanto-odontoid joint is closer to the physiological status of a human body.

The invention provides a 2.5D braided structure-based high-angular stability frequency selective surface and aims at improving the angular stability of the frequency selective surface. The 2.5D braided structure-based high-angular stability frequency selective surface comprises M*N passive resonance units, wherein each passive resonance unit comprises a dielectric slab, a first metal patch printedon the upper surface of the dielectric slab, a second metal patch printed on the lower surface of the dielectric slab, and metallized through holes; each first metal patch comprises six rotational symmetric first strip groups; each second metal patch comprises six rotational symmetric second strip groups; various strips in the second strip groups are located in gaps, in corresponding positions onthe lower surface, of various corresponding strips in the first strip groups; and the strips in the first metal patches and the second metal patches are connected through the corresponding metallizedthrough holes which penetrate through the dielectric slabs to form a 2.5D braided structure. According to the 2.5D braided structure-based high-angular stability frequency selective surface, good angular stability is achieved on the basis of miniaturization, and the 2.5D braided structure-based high-angular stability frequency selective surface can be applied to the aspects of communications andradars.

The invention is a broadband wave-transparent frequency-selective absorber based on a 2.5D structure, which solves the problem of narrow wave-transmission bandwidth of the existing frequency-selective absorber. The frequency selective absorber is composed of a loss layer, a lossless layer and an air layer. Periodically arranged resonators are printed on the loss layer. Each resonator subunit rotates 90° and 180° along the center of the dielectric plate with 0° as the reference direction. ° and 270° positioning; each subunit has short and long single-sided rounded corners, double-sided rounded corners and rectangular metal patches of equal width; long and short single-sided rounded corners are printed alternately on the medium The same double-sided rounded metal patch on the upper and lower layers of the board forms a 2.5D bent metal strip along a right-angle bending path. The invention uses a 2.5D structure to form a right-angle bent metal strip structure, broadens the wave-transmission bandwidth of the frequency selective absorber, and realizes wide wave-transmission band, bilateral wave absorption, polarization insensitivity, angle stability and small unit size characteristics, and is suitable for Broadband antenna system with stealth requirements.

The invention relates to a meter-wave radar low-elevation height measurement method based on robust principal component analysis noise reduction, and the method comprises the steps: carrying out the modeling of an array receiving signal of a meter-wave radar into a two-dimensional receiving signal matrix, and obtaining an array receiving signal model; establishing a convex optimization model of a low-rank signal matrix and a sparse noise matrix by adopting a noise reduction method based on robust principal component analysis; solving the convex optimization model by using an improved non-precise augmented Lagrangian multiplier method to obtain an optimal low-rank signal matrix without noise pollution; establishing a covariance matrix by using the optimal low-rank signal matrix, and constructing the maximum likelihood estimation of the direct wave elevation direction of arrival in combination with the covariance matrix and the synthetic steering vector to obtain a target elevation estimation value; and calculating the target height by using the target elevation angle estimated value. According to the method, the problems that in the prior art, under the conditions of non-uniform noise, low signal-to-noise ratio and few snapshots, the angle measurement performance is reduced, and the angle resolution is insufficient are solved, and the method has high angle measurement stability and good angle resolution.

The invention discloses a bionic low-friction artificial atlanto-odontoid joint which comprises an atlas component, an axis component and a screw, wherein the atlas component comprises a cup-and-ball joint and side wings; the cup-and-ball joint comprises a ball cup and a circular truncated cone-shaped housing arranged at the lower end of the ball cup; the side wings are provided with symmetric lock screw holes; the axis component is divided into an upper part and a lower part; the upper part comprises a polyethylene ball head sleeve and an irregular cylinder platform below the ball head sleeve; the bottom of the cylinder platform is designed into a multi-toothed structure; the lower part is matched with the front structure of an axis body; three locking screw holes formed in a Chinese character 'pin' shape are formed in the lower part; hydroxyapatite coatings are designed at the contact parts of the joints and the bone surface. On the premise of keeping the rotation function of the atlas and axis, the limited lateral bending and flexion and extension functions of the atlas and axis are realized, the design depth of the cup-and-ball joint is large, and the dislocation risk is reduced, so that the atlanto-odontoid joint is closer to the physiological status of a human body, and joints between the atlas component and denticulations are made of metal-on-polyethylene, so that the friction and collision sound is reduced, and the revision possibility is reduced.

The invention discloses a dual-polarization broadband external suppression three-dimensional frequency selective surface. The frequency selective surface is a three-dimensional periodic structure processed by a dielectric substrate, which includes a square coaxial waveguide and a parallel plate waveguide. The surface of the dielectric substrate has a metal patch, and the two ends of the metal patch in the electromagnetic wave propagation direction are provided with rectangular grooves, and the metal via holes in the dielectric substrate are connected to the metal patches on both sides. The parallel slab waveguides form a dual-mode resonator, producing a passband containing two transmission poles, and due to the interaction between the two waveguides, a wide stopband containing two transmission zeros near the passband. The invention has low polarization sensitivity in the dual-polarization working mode, can control the frequency range of the passband and the stopband by changing its related physical parameters, realizes dual-polarization application and has good incident angle stability.