61results about How to "Reduce RCS" patented technology

The invention belongs to the technical field of materials and radomes, and specifically relates to a single-passband bilateral wave-absorbing composite metamaterial and a radome and an antenna system including the same. The single-passband bilateral wave-absorbing composite metamaterial comprises a dielectric substrate (100) made of a non-conductive material and four periodic metamaterial structure layers embedded into the dielectric substrate. The four periodic metamaterial structure layers are respectively a resistive film layer (102), a first metal patch layer (103), a second metal patch layer (104) and a third metal patch layer (105) in sequence from top to bottom. The metal patch layers for realizing frequency selection enable an array antenna to keep good radiation characteristic and communicate freely in an X band; and meanwhile, in the S band, Ku band and K band at the two sides of the passband of the X band, the resistive film layer with wave absorption characteristic and the metal patch layers in the composite metamaterial radome work together, and electromagnetic wave which is incident on the radome and then reflected back by the metal patch layers is well absorbed.

The invention discloses a wing-borne low-scattering ultra-wideband conformal phased array based on a strong coupling effect. The whole antenna structure of the array is subjected to conformal processing, and + / -45 degree scanning in the arraying direction is realized within a broadband of 0.5-2GHz. Compared with the traditional planar ultra-wideband phased array, the phased array disclosed by theinvention has significant low-scattering characteristics inside and outside the working band of the antenna. The whole antenna structure mainly includes a coaxial feeding structure of an antenna radiation unit, a gradient line balun used for connecting an antenna radiation patch and the feeding structure, a metal ground plate which is conformal with a flight carrier, a parasitic metal block located on the metal ground plate, a conformal dielectric substrate used for supporting the radiation structure of the whole phased array, connected long-slot conformal radiation patches based on the strongcoupling effect, a conformal dielectric substrate used for supporting a resistive electromagnetic metamaterial, a circular resistive electromagnetic metamaterial with an ultra-wideband electromagnetic wave absorbing effect and parasitic slots on both sides of the antenna radiation unit.

The invention discloses a low-profile and low-scattering ultra-wideband phased array antenna loaded with a polarization selective wave metamaterial absorber. E-face + / -60-degree scanning and H-face + / -60-degree scanning are realized in a wide band of 6-18GHz, and the cross-section height is only 0.42 of the high frequency (18Ghz) wavelength. The cross polarization of the antenna can be effectivelyimproved through a polarization grating printed on the back surface of a radiation patch unit, and meanwhile, through the loaded polarization selective wave metamaterial absorber, the cross polarization RCS of the antenna is remarkably reduced within the full frequency range of the antenna working frequency without affecting the radiation performance of the antenna, and the absorption effect of the large-angle incident cross polarization electromagnetic wave is good.

A structure, and a method for modifying the design of a structure, are provided such that the structure includes features designed to reduce and preferably minimize the radar cross-section of the structure over one or more predetermined frequency ranges. A structure is provided having an inclined surface, wherein the angle of inclination is selected for which the level of radar cross section is below a local maximum in the sidelobes in each of the scattering patterns of incident electromagnetic radiation at frequencies within one or more predetermined frequency ranges. In the particular case of a tower, for example of a wind turbine, the radar cross-section of the tower may be minimized for two or more radar bands by appropriate selection of the angle of inclination of a frusto-conical portion of the tower. Ideally, the tower is constructed entirely in the form of a cone frustum.

The invention relates to a three-dimensional novel band absorption type broadband frequency selection structure. The conventional wave-absorbing type frequency selection structure is based on two or more two-dimensional array planes in a cascaded manner, and consequently, narrow passband, high insertion loss and not excellent wave-absorbing performance are caused. The three-dimensional broadband wave-absorbing frequency selection structure is established by adoption of a mode of a band elimination channel in combination with a wave-absorbing channel structure, so that low insertion loss in lowfrequency passband, and high frequency broad wave-absorbing band can be realized; and the structure has high wave-absorbing efficiency and extremely high angle stability.

The invention discloses a compact low-RCS metasurface antenna array and a design method thereof. The antenna array comprises a metal patch layer, an intermediate dielectric layer, a metal backboard layer and a plurality of coaxial metal feed columns, and the metal patch layer, the intermediate dielectric layer and the metal backboard layer are seamlessly stacked in sequence from top to bottom; andthe plurality of coaxial metal feed columns respectively penetrate through the metal patch layer, the intermediate dielectric layer and the metal backboard layer. According to the invention, the tworadiation unit chessboards are arranged to realize coherent cancellation of the scattering field of the whole antenna, and the scattering field is dispersed to an angle without threat, so that the characteristic of low radar scattering cross section of the antenna broadband is realized.

The invention discloses a RCS reduction method of a phased array antenna based on scattering polarization reconfiguration. The RCS reduction method of the phased array antenna based on the scatteringpolarization reconfiguration comprises the following steps that S1, N array units with polarization reconfiguration are arranged on the phased array antenna, each array unit comprises three differentpolarization modes, and the N array units are regularly arranged in a rectangular grid shape; S2, when the phased array antenna radiates, N array units are in the same polarization mode to form a unified polarization array; and S3, after the radiation of the phased array antenna is stopped, the polarization of the N array units is randomly distributed to form a random polarization array. The RCS reduction method of the phased array antenna based on the scattering polarization reconfiguration can significantly reduce the RCS after the radiation of an array antenna is stopped on the basis of notaffecting the radiation performance of the array antenna.

The invention belongs to structure design technologies, and relates to a cabin door receiving-releasing mechanism. A low-RCS embedded cabin door mechanism disclosed by the invention comprises a cabin door and a drive mechanism, wherein the drive mechanism comprises a left slide rail and a right slide rail which are parallel and fixed on a body respectively; a front link rod and a rear link rod sleeve the middle parts of the left slide rail and the right slide rail, and capable of sliding along the slide rails; one end of an action barrel is hinged with the body, and the other end is hinged with the hinged part of a first pull rod and a second pull rod; the other end of the first pull rod is hinged to the middle part of a corker arm; one end of the corker arm is hinged to the body, and the other end of the corker arm is hinged with a third pull rod; the other end of the third pull rod is hinged with a rotary rocker arm through a joint bearing; the rotary rocker arm is hinged with a link rod and capable of rotating around the link rod; the lower end of the rotary rocker arm is hinged with the joint of the cabin door; rear-end joints at the both sides of the cabin door are hinged with the rear link rod respectively. The low-RCS embedded cabin door mechanism disclosed by the invention adopts an embedded receiving-releasing mechanism, and solves the problems of too high RCS, too high flight resistance and the like caused by that a conventional cabin door is exposed to the outer surface of the body while being opened.

The invention discloses a low-RCS metasurface antenna array based on a coding idea and a design method thereof. The antenna array comprises a first dynamic scattering metal patch layer, a first dielectric layer, a metal backboard layer, a second dielectric layer, a bottom metal feed network layer, a plurality of coaxial metal feed columns, and a plurality of switching diodes. The metal layers and the dielectric layers are sequentially and seamlessly laminated and pressed together; the plurality of coaxial metal feed columns respectively penetrate through the first dynamic scattering metal patch layer, the first dielectric layer, the metal backboard layer, the second dielectric layer and the bottom feed network layer from top to bottom; the metal backboard layer is provided with a plurality of corresponding holes which are used for being isolated from the metal feed columns. According to the invention, the scattering phase of the dynamic scattering metal layer is further changed by changing the on-off state of a switching diode, and the overall scattered field coherent offset of the antenna is realized to achieve the stealth effect while the radiation performance of the antenna is not affected.

The invention provides a low-RCS phased-array antenna and an RCS reduction method thereof. Each antenna unit comprises four layers of structures, namely, a radiation patch layer, a cross-shaped feed structure layer, a floor layer and a direct-current feed layer, and every two adjacent layers are separated through a dielectric substrate. Switching among antenna circular polarization modes and switching among antenna feed points are achieved by controlling on-off of PIN diodes, so that the effect of equivalent rotation of the antenna units in the horizontal direction is achieved, and a phase difference of 180 degrees, which is twice of the rotation angle, of the scattering fields of the antenna units is achieved. The scattering fields of the antenna units are counteracted in a far field anddispersed to a wider angular domain space, so that the RCS of the array antenna is reduced. The scattering phases of the antenna units are directly controlled, so that the scattering fields of the array elements cannot be coherently superposed or reflected to a threat-free angle, and the RCS of the array is reduced.

The invention discloses an ultralow-profile low-scattering ultra-wideband phased-array antenna based on electromagnetic metamaterial loading, which realizes E-plane + / -70-degree scanning and H-plane + / -60-degree scanning in a 6-18GHz broadband, and the profile height of the ultralow-profile low-scattering ultra-wideband phased-array antenna is only 0.28 high-frequency (18GHz) wavelength. The loaded electromagnetic metamaterial is composed of a split ring periodic structure, an I-shaped resistive patch, an intersecting long-strip periodic structure and a plurality of wide-angle impedance matching layers, and through the integrated design of the electromagnetic metamaterial and the phased-array antenna, the phased-array antenna has the ultra-wide-band and ultra-wide-angle scanning characteristic and meanwhile has the remarkably low profile height. In addition, the cross polarization RCS of the phased-array antenna is remarkably reduced within the full-frequency range of the working frequency of the phased-array antenna, and meanwhile, the radiation efficiency of the phased-array antenna is kept above 95%.

The invention discloses a traction unit of a target support rotary table with two supporting mechanisms and one suspension mechanism. The traction unit is mainly composed of three parts, namely a linear traction mechanism, a tensioning direction-changing mechanism and a low-scattering suspension mechanism. The linear traction mechanism is driven by a servo motor, subjected to transmission conducted through ball screws and guided through linear guide rails. By means of the tensioning direction-changing mechanism, horizontal movement of a traction rope can be converted into vertical movement, and it can be guaranteed that the direction of the traction rope remains unchanged in the ascending and descending processes. By means of the low-scattering suspension mechanism, the traction rope can be connected with a to-be-measured target, and by means of the suspension mechanism, two-dimensional rotation movement, namely rotation movement conducted in the vertical direction and pitching movement conducted in the horizontal direction, can be achieved. The suspension mechanism is compact in structure; and electromagnetic wave reflection conducted by the suspension mechanism can be blocked through a low-scattering trimming cover, so that the whole suspension mechanism is low in RCS, and influence on RCS measurement conducted on the to-be-measured target is small.

This invention relates to a system and method of enabling the passive reduction of radar cross-section of an object using radar absorbing materials on composite structures, such as an aircraft or unmanned aerial vehicle. The system includes a coating that is applied to a composite structure. The method includes a method of applying a coating to a composite structure.

The invention provides a Ka-band complete-polarization ultrathin frequency selective surface. The Ka-band complete-polarization ultrathin frequency selective surface comprises a dielectric substrate and metal foil layers, wherein the metal foil layers are attached onto an upper surface and a lower surface of the substrate, the metal foil layers on the upper / lower surfaces comprises periodically-arranged upper / lower periodic micro unit structures, each unit structure is square and comprises three circular-annular gaps, four metal short-circuit gaps are loaded on an outer-side circular-annular gap and are uniformly arranged on a round ring, and the lower periodic micro unit structures are corresponding to the upper periodic micro unit structures. The invention also provides an antenna coverfabricated by employing the surface, and the antenna cover can be covered in a radiation direction of an antenna system. By the complete-polarization ultrathin frequency selective surface antenna cover, favorable rotation characteristic of the antenna within frequency bands of the Ka band being 33-37.5GHz can be maintained, free transceiving and communication can be achieved, meanwhile, good out-of-band rejection performance outside passband can be achieved, RCS of the antenna is reduced, and the purpose of hiding the antenna is achieved.

The invention discloses a miniaturized passive flexible band-pass frequency selective surface for an antenna housing. The miniaturized passive flexible band-pass frequency selective surface comprisesan upper-layer metal periodic array and a lower-layer substrate, the metal periodic array comprises a plurality of metal units which are periodically arranged and distributed; the metal unit comprisesfour bending lines which are symmetrical about the center. According to the invention, the miniaturized frequency selective surface is combined with the ultrathin substrate; manufacturing is easy, the frequency selective surface can be attached to the surface of the complex curved surface radome, the electromagnetic performance of in-band wave transmission and out-of-band stealth is achieved by reducing the unit size of the upper layer metal periodic array and shortening the array period, good angle stability and wave transmission performance are achieved, and important application prospectsare achieved.

The invention discloses a light-controlled reconfigurable apparatus of a phase-controlled-array array antenna. The light-controlled reconfigurable apparatus comprises a microstrip feeder line layer, a microwave dielectric substrate, a mixed coverage layer, a laser array, a laser controller and an optical fiber bundle, wherein the mixed coverage layer is formed by a silicon wafer layer and a metal layer in a spliced manner; the microwave dielectric substrate is arranged on the upper surface of the microstrip feeder line layer; the mixed coverage layer is arranged on the upper surface of the microwave dielectric substrate; one end of the optical fiber bundle is connected with the laser transmitting end of the laser array while the other end of the optical fiber bundle is fixed on the upper surface of the silicon wafer layer; the laser controller controls starting and closing of each laser in the laser array; a laser signal emitted from the laser array passes through the optical fiber bundle to be guided to irradiate an appointed region on the surface of the silicon wafer layer; and a phase-controlled signal is input from a feeder line port of the microstrip feeder line layer, and the starting and closing of each laser is changed through the laser controller so as to form array antennas of different caliber directions. Compared with the existing phase-controlled array antenna technology, the phase-controlled-array array antenna disclosed in the invention can obtain a larger space scanning angle.

The invention discloses a frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased-array antenna based on a strong coupling effect. The frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased-array antenna is completely conformal on the surface of a frustum, the distance between dipole radiation units along the circumferential direction is linearly changed along with the generatrix of the frustum, the dipole radiation units are arranged in a conically-changed array mode, and + / -45-degree scanning of an E surface and an H surface is realized in a broadband range of 6-18GHz. By loading strip metal patches, active standing wave deterioration caused by a conformal environment is effectively improved. In addition, a quasi-periodic electromagnetic metamaterial is loaded in the full-frequency range of the working frequency of the phased-array antenna, so that the cross polarization RCS of the phased-array antenna is remarkably reduced, and the overall radiation efficiency of the conformal phased array is ensured to be at a relatively high level. Finally, the application of a full split ring helps to realize the scattering features of the phased-array antenna while the phased-array antenna has the ultra-wide-band wide-angle scanning feature.

The invention discloses an electromagnetic camouflage metamaterial and application thereof. The metamaterial comprises a metal bottom layer and a dielectric layer which are sequentially arranged frombottom to top, wherein a plurality of metal patches are arranged on the dielectric layer, and the area of each metal patch accounts for 3%-6% of the area of the upper surface of the dielectric layer.Compared with the metamaterial of the basic unit at a specific position, the metamaterial is randomly distributed in the basic units, and the metal patches of the adjacent units can be overlapped to have larger design flexibility. The electromagnetic camouflage metamaterial is simple in structure, can perform direct spraying at a target surface except manufactured through the three-dimensional printing technology, and is wider in application. For target objects with different sizes, unit distribution is not required to rearrange, and the lengths and the area ratio of the metal patches are onlyneeded.

The invention provides an array antenna radiation and scattering comprehensive optimization method based on electromagnetic cancellation, and aims to effectively reduce RCS of an array antenna while realizing good radiation characteristics. The implementation steps are as follows: constructing an electromagnetic cancellation scene model; acquiring a radiation field of an array antenna; acquiring ascattering field of the array antenna; calculating the total field of the array antenna; defining an optimization algorithm fitness function fit (x); and obtaining a comprehensive optimization resultof the radiation and scattering characteristics of the array antenna by utilizing an optimization algorithm. According to the invention, the problem of comprehensive optimization of the radiation andscattering characteristics of the array antenna is solved, and the RCS of the array antenna is effectively reduced while good radiation characteristics are realized.

The invention relates to an aircraft nose with arrises, which comprises an upper nose surface, the arrises, and the lower nose surface, the arrises divide the nose into the upper nose surface and the lower nose surface by means of large-curvature splines, and the upper nose surface and the lower nose surface are bridged by large-curvature curves; and the arrises are arranged on both sides of the nose, and extend from the front edge of the nose along a designed direction from the front to the back. The arrises delay and weaken the vortex strength of the nose, so that the maximum available attack angle and operability of an aircraft are effectively increased; moreover, the forward and anterolateral RCS (Radar Cross-Section) values of the aircraft are reduced, the distance at which the aircraft can be detected is reduced, and thereby the stealth performance and survivability of the aircraft are enhanced.

The embodiment of the invention provides an antenna device capable of reducing directional diagram jitter. The antenna device is composed of a ground layer, a dielectric layer and an antenna layer. The antenna layer comprises a comb-shaped antenna and a chessboard structure distributed around the comb-shaped antenna. The chessboard structure is composed of patches, and each column and each transverse row are formed by arranging PECs and AMCs in a staggered mode. And the PEC and the AMC are both regular polygon patches. The chessboard type structure can reduce the radar scattering cross sectionof the surface of the antenna and reduce the jitter of the directional diagram of the radar antenna.

A repair assembly for a screw head special for a radar stealthy combat aircraft comprises a wave-absorbing ring piece and a wave-absorbing groove core which are in clearance fit. The wave-absorbing groove core is arranged in the wave-absorbing ring piece in a penetrating-sleeved mode. The wave-absorbing ring piece is a circular-ring-shaped body. The upper end face of the wave-absorbing ring piece is a smooth plane. The lower end face of the wave-absorbing ring piece is a rough plane. The wave-absorbing groove core is a step column and comprises a groove core cap, an upper groove core body, a lower groove core body, a ventilation channel and a groove core rod. The center lines of the groove core cap, the upper groove core body, the lower groove core body and the groove core rod coincide on one straight line, and the groove core cap, the upper groove core body, the lower groove core body and the groove core rod are in series connection sequentially to form a whole. According to the repair assembly, the radar stealthy effect is prominent, reliability is high, operation is simple, installation is convenient, and the maintenance efficiency of the radar stealthy combat aircraft during combat is high.

The invention discloses an antenna housing with wave-transparent, invisible and bulletproof functions, and belongs to the technical field of military antenna protective covers. The invention aims to solve the problems that a traditional antenna housing is easily detected by enemy radars in a modern war environment, is easily struck and damaged by fragments or bullets, and is low in battlefield viability. The antenna housing with the wave-transparent, invisible and bulletproof functions comprises a wave-transparent outer layer, a bulletproof layer, a wave-transparent inner layer and reinforcing ribs, and frequency selection planes of carbon fiber array units are woven on the upper surface and the lower surface of the bulletproof layer. On the basis of meeting the performance requirements of electrical, mechanical and environmental adaptation and the like of a traditional antenna housing, the antenna housing has the functions of wave transmission in a working frequency band and invisibility outside the working frequency band; it is guaranteed that the antenna housing can still work normally when being hit by fragments or bullets; and the battlefield viability of the antenna housing is improved.

The invention discloses a metasurface integrated with a three-dimensional protruding top layer structure, and belongs to the technical field of terahertz wave band metamaterials and metasurfaces. The metasurface structure unit of the metal hemisphere comprises a metal back electrode, a dielectric layer and a three-dimensional metal hemisphere structure layer which are arranged in sequence, and the dielectric layer is composed of a plurality of metal hemispheres by using a flexible material hemisphere unit structure. The three-dimensional metal hemisphere structure has good isotropy and has the characteristic that the three-dimensional metal hemisphere structure is insensitive to an incident plane wave angle in a terahertz wave band. And further in combination with the idea of communication modulation coding, a coding matrix is realized by combining and designing metamaterial unit arrays with different sizes, the RCS is effectively reduced, and effective regulation and control of the terahertz wave beam are realized. In the vicinity of 0.96 THz and 1.5 THz, two metal hemispherical top-layer metasurface surfaces can have good insensitive characteristics to an incident angle within an electromagnetic wave incident angle of 60 degrees, and terahertz waves can be effectively regulated and controlled.

The invention discloses a resistive film-based broadband metamaterial wave-absorbing unit and a wave-absorbing material. The wave-absorbing unit is formed by processing a resistive film; the effect ofabsorbing electromagnetic waves is achieved by changing the structure of the metamaterial wave-absorbing unit and the sheet resistance of the resistive film. When electromagnetic waves irradiate intothe metamaterial wave-absorbing unit, the electromagnetic waves can be effectively absorbed and consumed, and therefore, a broadband wave-absorbing characteristic is achieved. The metamaterial wave-absorbing units are periodically arranged to form a wave-absorbing array; the wave-absorbing array is combined with a microstrip patch antenna, so that the reduction of the RCS of the antenna can be realized on the premise of not changing the radiation performance of the microstrip patch antenna, and therefore, the purpose of the stealth of the antenna is achieved.