WO2013013470A1 - 偏馈式雷达天线 - Google Patents

偏馈式雷达天线 Download PDF

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Publication number
WO2013013470A1
WO2013013470A1 PCT/CN2011/083010 CN2011083010W WO2013013470A1 WO 2013013470 A1 WO2013013470 A1 WO 2013013470A1 CN 2011083010 W CN2011083010 W CN 2011083010W WO 2013013470 A1 WO2013013470 A1 WO 2013013470A1
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Prior art keywords
metamaterial
refractive index
layer
artificial
unit
Prior art date
Application number
PCT/CN2011/083010
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English (en)
French (fr)
Inventor
刘若鹏
季春霖
岳玉涛
宿超
Original Assignee
深圳光启高等理工研究院
深圳光启创新技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Priority claimed from CN201110210366.8A external-priority patent/CN102904040B/zh
Priority claimed from CN 201110210393 external-priority patent/CN102480029B/zh
Application filed by 深圳光启高等理工研究院, 深圳光启创新技术有限公司 filed Critical 深圳光启高等理工研究院
Publication of WO2013013470A1 publication Critical patent/WO2013013470A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
    • H01Q15/0086—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials

Definitions

  • the present invention relates to the field of radar antennas, and more particularly to an offset feed radar antenna using a metamaterial. ⁇ Background technique ⁇
  • the radar antenna converts the spherical wave radiated by the feed into a plane wave through the reflector, thereby achieving directional reception or transmitting electromagnetic waves.
  • the reflector currently used is a parabolic shape, and the feed is located near the focus of the reflector.
  • the working principle of the radar antenna is similar to that of the optical mirror.
  • the existing radar parabolic antenna is shown in Figure 1. It includes the source 1, the parabolic reflector 2 and the bracket 3.
  • the transmitting or receiving electromagnetic waves are placed at the focus of the parabolic reflector 2.
  • Feed 1 using the focusing characteristics of the parabolic reflector 2, the spherical wave emitted by the feed 1 is reflected by the parabolic reflector 2 and converted into a plane wave to form a narrow beam that radiates the strongest along the parabolic axial direction.
  • a parabolic reflecting surface In order to manufacture a parabolic reflecting surface, it is usually formed by mold casting or by a numerically controlled machine tool.
  • the process of the first method includes: making a parabolic mold, casting a paraboloid, and installing a parabolic reflector.
  • the process is relatively complicated, the cost is high, and the shape of the paraboloid is relatively accurate to achieve the directional propagation of the antenna, so the processing accuracy is relatively high.
  • the second method uses a large-scale CNC machine to perform paraboloid machining. By editing the program, the path of the tool in the CNC machine is controlled to cut the desired paraboloid shape. This method is very precise, but it is difficult and costly to manufacture such a large CNC machine.
  • Metamaterials are artificial composite structural materials that have extraordinary physical properties not found in natural materials. By superposing the ordered structure of the microstructure, the metamaterial can change the relative dielectric constant and magnetic permeability of each point in the metamaterial, and realize the non-uniformity of the refractive index distribution of the substance to control the propagation path of the electromagnetic wave in the material.
  • the object of the present invention is to overcome the problem of complicated manufacturing process of manufacturing a parabolic antenna in the prior art.
  • An offset feed radar antenna is provided, which proposes a simple radar antenna with a planar reflector, which has the advantage that a parabolic antenna can receive or emit electromagnetic waves directionally, and avoids the production of a parabolic antenna.
  • the complex process of time is provided, which proposes a simple radar antenna with a planar reflector, which has the advantage that a parabolic antenna can receive or emit electromagnetic waves directionally, and avoids the production of a parabolic antenna. The complex process of time.
  • An offset feed radar antenna comprising: a feed source for radiating electromagnetic waves; a metamaterial panel, an electromagnetic wave for radiating the feed source Converting from a spherical electromagnetic wave into a planar electromagnetic wave, the antenna further comprising a reflecting plate attached to one side of the metamaterial panel for reflecting electromagnetic waves to the metamaterial panel for concentrated refraction and radiating to a distant place, the feeding source being located The other side of the metamaterial panel and in the non-facing region of the metamaterial panel, the metamaterial panel comprising a plurality of core layers having the same distribution of refractive indices, each core layer comprising a plurality of metamaterials Unit, the metamaterial unit includes a unit substrate and an artificial metal microstructure, and a refractive index of each core layer of the metamaterial panel is circularly distributed with a positive projection of the feed on each core layer. , and the refractive index gradually decreases as the radius increases, and the refractive index
  • the metamaterial unit further includes a first filling layer, the artificial metal microstructure is located between the unit substrate and the first filling layer, and the material filled in the first filling layer includes air and artificial a metal microstructure and a medium of the same material as the unit substrate.
  • the meta-material panel further includes a plurality of gradation layers distributed on one side of the core layer, each of the gradation layers including a sheet-like substrate layer, a sheet-shaped second filling layer, and a setting layer An air layer between the substrate layer and the filling layer.
  • the medium filled in the second filling layer includes air and a medium of the same material as the substrate layer.
  • first substrate layer and the second substrate layer are each made of a ceramic material, an epoxy resin, a polytetrafluoroethylene, an FR-4 composite material or an F4B composite material.
  • each core layer of the metamaterial panel is centered on the orthographic projection of the feed on each core layer, and the radius r varies as follows:
  • max represents the maximum refractive index value in each core layer
  • d represents the total thickness of all core layers Degrees
  • ss represents the distance from the feed to the core layer closest to the feed position
  • n ⁇ represents the refractive index value at the radius r of the plurality of core layers.
  • the refractive index in each of the graded layers of the metamaterial panel is uniformly distributed, and the variation of the refractive index distribution between the plurality of graded layers is as follows:
  • the gradient layer is the outermost gradient layer.
  • the man-made metal microstructure is a planar structure or a three-dimensional structure composed of at least one wire responsive to an electromagnetic field, the wire being a copper wire or a silver wire.
  • the wire is attached to the unit substrate by etching, plating, drilling, photolithography, electron engraving or ion etching.
  • the man-made metal microstructure is any one of a derivative shape, a snow flower shape or a snowflake shape derived from a "work" shape or a "work” shape.
  • each of the metamaterial units is formed with an artificial hole structure filled with a medium having a refractive index smaller than a refractive index of the unit substrate, and the artificial hole structures in all the super material units are filled.
  • the medium of the same material, the arrangement of the volume of the artificial pore structure disposed in the metamaterial unit in each core layer is: the volume of the artificial pore structure formed on the metamaterial unit with the feed in each
  • the orthographic projection on the core layer is a semicircular distribution of the center of the circle. As the radius increases, the volume of the artificial pore structure formed on the material unit increases, and the volume of the artificial pore structure formed on the metamaterial unit at the same radius increases. the same.
  • each of the metamaterial units is formed with an artificial hole structure filled with a medium having a refractive index greater than a refractive index of the unit substrate, and the artificial hole structures in all the metamaterial units are filled.
  • the medium of the same material, the arrangement of the volume of the artificial pore structure disposed in the metamaterial unit in each core layer is: the volume of the artificial pore structure formed on the metamaterial unit is fed by The orthographic projection of the source on each core layer is a semicircular distribution of the center of the circle. As the radius increases, the volume of the artificial pore structure formed on the material unit gradually decreases, and the metamaterial unit having the same radius is formed.
  • the artificial pore structure is the same volume.
  • the artificial hole structure is filled with a medium having a refractive index smaller than a refractive index of the unit substrate, and the artificial holes in all the super material units
  • the structure is filled with a medium of the same material, and the arrangement of the number of the artificial hole structures disposed in the metamaterial unit in each core layer is: the number of the artificial hole structures formed on the metamaterial unit is the feed source
  • the orthographic projection on each core layer is a semicircular distribution of the center of the circle. As the radius increases, the number of manhole structures formed on the material element gradually increases, and the artificial material formed on the metamaterial unit at the same radius The number of pore structures is the same.
  • the artificial hole structure is filled with a medium having a refractive index greater than a refractive index of the unit substrate, and the artificial holes in all the super material units
  • the structure is filled with a medium of the same material, and the arrangement of the number of the artificial hole structures disposed in the metamaterial unit in each core layer is: the number of the artificial hole structures formed on the metamaterial unit is the feed source
  • the orthographic projection on each core layer is a semi-circular distribution of the center of the circle. As the radius increases, the number of man-made hole structures formed on the material element gradually decreases, and the artificial material formed on the metamaterial unit at the same radius The number of pore structures is the same.
  • the present invention has the following beneficial effects:
  • An offset feed type radar antenna the structure of the planar antenna is simple, and the characteristics of the electromagnetic wave are concentrated by using the metamaterial, so that the radar antenna does not depend on the shape of the electromagnetic wave convergence device,
  • the complicated manufacturing process of processing a conventional parabolic antenna is eliminated, and at the same time, the advantages of the conventional parabolic antenna directional receiving or transmitting electromagnetic waves can be realized.
  • the present invention employs an offset-feeding radar antenna, so that the radiation of the electromagnetic wave is no longer blocked by the feed, and the influence of the radiated electromagnetic wave on the feed is also avoided.
  • FIG. 2 is a schematic diagram of an offset feed radar antenna according to a first embodiment of the present invention
  • FIG. 3 is a schematic diagram of an offset feed radar antenna according to a first embodiment of the present invention.
  • FIG. 4 is a schematic structural view of the metamaterial panel according to the first embodiment of the present invention.
  • FIG. 5 is a schematic structural diagram of the core layer according to the first embodiment of the present invention.
  • FIG. 6 is a schematic structural view of the core layer according to the first embodiment of the present invention.
  • FIG. 7 is a schematic structural view of the metamaterial unit according to the first embodiment of the present invention.
  • FIG. 8 is a schematic structural view of the gradation layer according to the first embodiment of the present invention.
  • FIG. 9 is a schematic view showing a change in refractive index of a core layer according to a first embodiment of the present invention.
  • Figure 10 is a schematic view showing a change in refractive index of a core layer according to a first embodiment of the present invention
  • FIG. 11 is a schematic diagram of an offset feed radar antenna according to a second embodiment of the present invention.
  • FIG. 12 is a schematic diagram of an offset feed radar antenna according to a second embodiment of the present invention.
  • FIG. 13 is a schematic structural view of the metamaterial panel according to a second embodiment of the present invention.
  • Figure 14 is a schematic structural view of the core layer of the second embodiment of the present invention.
  • Figure 15 is a schematic structural view of the metamaterial unit according to a second embodiment of the present invention.
  • Figure 16 is a schematic view showing the structure of the gradation layer of the second embodiment of the present invention.
  • FIG. 2 and FIG. 3 are schematic diagrams showing the structure of a feedforward radar antenna according to the present invention.
  • the antenna includes a feed 10, a metamaterial panel 20, and a reflector 30.
  • the feed 10 and the emitter 30 are respectively located on the metamaterial panel 20.
  • the reflector 30 is closely attached to the metamaterial panel 20, and the orthographic projection of the point where the feed 10 is located on the metamaterial panel 20 is the midpoint of the bottom edge of the metamaterial panel 20.
  • the electromagnetic wave radiated from the feed 10 is a spherical electromagnetic wave, but the far-field direction performance of the spherical electromagnetic wave is not good, and there is a great limitation to the signal transmission of the spherical electromagnetic wave as a carrier at a long distance, and the fading
  • the present invention designs a metamaterial panel 20 having an electromagnetic wave concentrating function, which converts most of the electromagnetic waves radiated from the feed 10 from spherical electromagnetic waves into planar electromagnetic waves, and electromagnetic waves passing through the metamaterial panel 20.
  • the radar antenna After being reflected by the reflecting plate 30, it is again refracted and radiated through the metamaterial panel 20, so that the directivity of the radar antenna is better, the energy density of the main lobe of the antenna is higher, the energy is larger, and the signal transmission distance of the plane electromagnetic wave is used as a carrier. farther.
  • the metamaterial panel 20 includes a plurality of core layers 210 and a plurality of graded layers 220 distributed on one side of the feed source, each core layer 210 being composed of a plurality of layers.
  • a metamaterial unit comprising a unit substrate 211, a sheet-shaped first filling layer 213, and a plurality of man-made metal microstructures 212 disposed between the unit substrate 211 and the first filling layer 213, As shown in Figure 6 and Figure 7.
  • the material filled in the first filling layer 213 may be air, an artificial metal microstructure, and a medium of the same material as the unit substrate, for example, when it is required that the equivalent refractive index in the metamaterial unit becomes large,
  • the first filling layer 213 may be filled with a metal microstructure or filled with a medium having a large refractive index; when the equivalent refractive index in the metamaterial unit is required to be small, the first filling layer 213 may be filled with an air medium. Or do not fill any media.
  • a plurality of metamaterial core layers 210 in the metamaterial panel 20 are stacked together, and the core layers 210 are assembled at equal intervals, or the front and back surfaces are integrally bonded together integrally between the two sheets.
  • the number of super-material core layers and the distance between each core layer can be designed according to requirements.
  • Each of the metamaterial core layers 210 is formed by an array of a plurality of metamaterial elements, and the entire metamaterial core layer 210 can be regarded as an array of a plurality of metamaterial units arranged in three directions of X, Y, and ,, as shown in FIG. 5. Shown.
  • the plurality of core layers 210 of the metamaterial panel 20 realize phase radiation of electromagnetic waves or the like after passing through the metamaterial panel 20 by changing the refractive index distribution inside thereof, that is, realizing spherical electromagnetic wave conversion radiated from the feed source 10 It is a plane electromagnetic wave.
  • the refractive index distribution of each of the metamaterial core layers 210 is the same, and only the refractive index distribution of one of the supermaterial core layers 210 is described in detail.
  • the refractive index distribution of the intermediate core layer 210 satisfies the following rules:
  • the refractive index profiles of 210 are all the same, and each core layer includes one with a feed 10 at each
  • the orthographic projection on the core layer 210 is a semi-circular area of the center, the refractive index at the center of the semi-circular area is a maximum value of 3 ⁇ 4 ⁇ and gradually decreases as the radius increases, and the refractive index at the same radius Similarly, as shown in FIG.
  • a change diagram of the refractive index in the r direction is given, but it should be understood that the refractive index change of the present invention is not limited thereto.
  • the design of the present invention is: When electromagnetic waves pass through the core layers 210 of each metamaterial, the deflection angle of the electromagnetic waves is gradually changed and finally radiated in parallel.
  • Sm ⁇ q* A «, where is the angle of the desired deflection electromagnetic wave, ⁇ « is the difference between the front and back refractive index changes, q is the thickness of the metamaterial functional layer and the required parameter value can be determined by computer simulation and The design purpose of the invention is achieved.
  • Figures 9 and 10 show a variation of the refractive index profile of the core layer of the metamaterial over the radius r.
  • the refractive index of electromagnetic waves is proportional to ⁇ ⁇ , where ⁇ is the magnetic permeability and ⁇ is the dielectric constant.
  • ⁇ is the magnetic permeability
  • ⁇ is the dielectric constant.
  • the electromagnetic wave will refract.
  • the refractive index distribution inside the substance is non-uniform, the electromagnetic wave is deflected toward a position where the refractive index is relatively large. Therefore, the refractive index of each point of the core layer 210 in the super-material panel 20 is designed to satisfy the above refractive index change rule.
  • the metamaterial unit is actually a cube rather than a point, the above semicircular area is only an approximate description, and the actual metamaterial units having the same or substantially the same refractive index are in a zigzag half circumference. Distributed on the top.
  • the specific design is similar to the programming mode (such as OpenGL) when the computer draws a semi-circular, semi-elliptical and other smooth curves with square pixels. When the pixel is small relative to the curve, the curve is smooth, and when the pixel is relatively The curve shows jagged when the curve is large.
  • the substrate 211 and the first filling layer 213 are distributed on the substrate.
  • the unit substrate 211 is made of a dielectric insulating material, and may be a ceramic material, a polymer material, a ferroelectric material, a ferrite material, a ferromagnetic material, or the like.
  • the material can be, for example, epoxy or polytetrafluoroethylene.
  • the artificial metal microstructure 212 is a metal wire which is attached to the unit substrate 211 in a certain geometric shape and is responsive to electromagnetic waves.
  • the metal wire may be a copper wire or a silver wire having a cylindrical or flat shape, and is generally made of copper. Because the copper wire is relatively cheap, of course, the cross section of the metal wire can also be other shapes, and the metal wire is etched, plated, A process such as drilling, photolithography, electron etching or ion etching is attached to the unit substrate 211.
  • the first filling layer 213 may be filled with a medium of different materials, may be the same material as the unit substrate 211, or may be an artificial metal.
  • each core layer 210 is composed of a plurality of metamaterial units, each of the metamaterial units having an artificial metal microstructure, each of the super material units responding to electromagnetic waves passing therethrough, thereby Affecting the transmission of electromagnetic waves in it, the size of each metamaterial unit depends on the electromagnetic wave that needs to respond, usually one tenth of the wavelength of the electromagnetic wave that is required to respond, otherwise the space contains the metamaterial unit of the man made metal microstructure 212.
  • the arrangement of spaces cannot be considered continuous in space.
  • the shape and size of the artificial metal microstructure 212 and its spatial distribution on the unit substrate 211 and the medium having different refractive indices filled in the first filling layer 213 can be adjusted.
  • the equivalent dielectric constant and equivalent permeability throughout the metamaterial in turn alter the equivalent refractive index throughout the metamaterial.
  • the man-made metal microstructure 212 adopts the same geometry, the larger the size of the artificial metal microstructure at a certain point, the larger the equivalent dielectric constant and the larger the refractive index.
  • the pattern of the artificial metal microstructure 212 used in this embodiment is an I-shaped derivative pattern.
  • the size of the snow-like artificial metal microstructure 212 is centered on the orthographic projection of the feed 10 on each core layer 210. , gradually becoming smaller toward the periphery.
  • the snow-like artificial metal microstructure 212 has the largest size, and the snow-like artificial metal microstructures 212 at the same radius have the same size, so the equivalent of each core layer 210
  • the electric constant gradually decreases from the center to the periphery, and the equivalent dielectric constant of the center is the largest. Therefore, the refractive index of each core layer 210 gradually decreases from the center to the periphery, and the refractive index of the center portion is the largest.
  • the pattern of the artificial metal microstructures 212 may be two-dimensional or three-dimensional, and is not limited to the embodiment.
  • the "work" shape used can be a derivative structure of the "work” shape, which can be a snowflake-like and snowflake-like derivative structure in which each side of the three-dimensional space is perpendicular to each other, or other geometric shapes, in which different artificial
  • the metal microstructures 212 may have the same pattern, but the design dimensions are different; the patterns and design dimensions may be different, as long as the electromagnetic waves emitted by the antenna unit are propagated through the metamaterial panel 20 and can be emitted in parallel.
  • the refractive index of each core layer 210 of the metamaterial panel 20 is centered on the orthographic projection of the feed 10 on each core layer 210, and the variation of the radius r is as follows. :
  • max represents the maximum refractive index value in each core layer 210
  • d represents the total thickness of all core layers 210
  • ss represents the distance of the feed source 10 to the core layer 210 closest to the feed position
  • each of the metamaterial grading layers 220 includes a sheet-like substrate layer 221, a sheet-shaped second filling layer 223, and an air layer 222 disposed between the substrate layer 221 and the second filling layer 223.
  • the substrate layer 221 may be a polymer, a ceramic material, a ferroelectric material, a ferrite material or the like.
  • the high molecular polymer is preferably a FR-4 or F4B material.
  • the refractive indices between the plurality of metamaterial graded layers 220 are different, in order to match the impedance of the air to the core layer 210, typically by adjusting the width of the air layer 222 and by filling the second fill layer 223 with different refractions.
  • the medium of the rate is used to achieve impedance matching.
  • the medium may also be the same material as the substrate layer 221, or may be air, wherein the metamaterial gradient layer 220 close to the air has a refractive index closest to the air and gradually becomes a refractive index toward the core layer 210. increase.
  • the refractive index of each of the gradient layers 220 of the metamaterial panel 20 is uniformly distributed, and the variation of the refractive index distribution between the plurality of graded layers 220 is as follows:
  • the core layer 210, the first layer of the gradient layer is the outermost layer.
  • the offset-feeding radar antenna of the present invention greatly increases the far-field power of the antenna by changing the refractive index distribution inside the super-material panel 20, thereby increasing the distance traveled by the antenna and increasing the antenna.
  • the front-to-back ratio makes the antenna more directional; and the invention adopts an offset-fed radar antenna, so that the feed does not block the electromagnetic wave radiation, and also avoids the influence of the radiated electromagnetic wave on the feed.
  • 11 and FIG. 12 are schematic diagrams showing the structure of an offset-fed radar antenna according to a second embodiment of the present invention.
  • the antenna includes a feed 10, a metamaterial panel 20', and a reflector 30.
  • the feed 10 and the emitter 30 are respectively located.
  • the reflector 30 is closely attached to the metamaterial panel 20', and the orthographic projection of the point where the feed 10 is located on the metamaterial panel 20' is the lower edge of the metamaterial panel 20' The midpoint.
  • the electromagnetic wave radiated from the feed 10 is a spherical electromagnetic wave, but the far-field direction performance of the spherical electromagnetic wave is not good, and the signal transmission with the spherical electromagnetic wave as a carrier at a long distance has a great limitation, and the attenuation is fast, and the present invention is designed by A metamaterial panel 20' having an electromagnetic wave converging function, the metamaterial panel 20' converts most of the electromagnetic waves radiated from the feed 10 from spherical electromagnetic waves into planar electromagnetic waves, and is reflected by the electromagnetic waves passing through the supermaterial panel 20' through the reflecting plate 30.
  • the metamaterial panel 20' includes a plurality of core layers 210' having the same refractive index distribution and a plurality of graded layers 220' distributed on the side close to the feed source 10, that is, the core layer 210'
  • the functional layer of the metamaterial panel 10 is composed of a plurality of metamaterial units. Since the metamaterial panel 20' needs to continuously respond to electromagnetic waves, the metamaterial unit size should be less than one fifth of the wavelength of the required response electromagnetic wave, this embodiment It is preferably one tenth of the wavelength of the electromagnetic wave.
  • the metamaterial unit includes a unit substrate 211 ' provided with one or more manhole structures 212'. Each of the core layers 210' thus provided with the artificial hole structure 212' is superposed to constitute a functional layer of the metamaterial panel 20', as shown in FIG.
  • the plurality of core layers 210' of the metamaterial panel 20' achieve phase radiation of electromagnetic waves or the like after passing through the metamaterial panel 20' by changing the refractive index distribution inside thereof, that is, radiating from the feed source 10
  • the spherical electromagnetic waves are converted into planar electromagnetic waves.
  • the refractive index distribution of each core layer 210' in this embodiment is the same, and is the same as the refractive index distribution of the core layer 210' in the previous embodiment.
  • only the refractive index distribution law of one metamaterial core layer 210' will be described in detail.
  • each core layer 210' is illustrated in Figure 10 by the design of the volume of the manhole structure 212', the medium filled within the manhole structure 212', and the density of the manhole structure 212'.
  • Each core layer 210' of the metamaterial panel 20' includes a semi-circular surface centered on the orthographic projection of the feed 10 on each core layer 210', and the refractive index at the center of the semi-circular surface is at most n max , having the same refractive index at the same radius, the larger the radius, the smaller the refractive index.
  • the refractive index change diagram is shown in Fig. 10, but it should be understood that the refractive index change of the present invention is not limited thereto.
  • the design of the present invention is: When electromagnetic waves pass through the core layers 210', the electromagnetic wave deflection angle is gradually changed and finally parallel radiation.
  • Sm ⁇ q* A «, where is the angle of the desired deflection electromagnetic wave, ⁇ is the difference between the front and back refractive index changes, q is the thickness of the metamaterial functional layer and can be determined by computer simulation to achieve the required parameter values and reach The design object of the present invention.
  • Figure 9 is a view showing the refractive index distribution of the core layer of the metamaterial shown in Figure 10 in the r direction.
  • the refractive index of electromagnetic waves is proportional to ⁇ ⁇ , where ⁇ is the magnetic permeability and ⁇ is the dielectric constant.
  • ⁇ is the magnetic permeability
  • ⁇ is the dielectric constant.
  • the electromagnetic wave will refract.
  • the refractive index distribution inside the material is non-uniform, the electromagnetic wave is deflected to a position where the refractive index is relatively large. Therefore, the refractive index of each point of the super-material panel 20' is designed to satisfy the above-mentioned refractive index change rule, which needs to be explained.
  • the metamaterial unit is actually a cube rather than a point, the above semicircular regions are only approximate descriptions, and the actual metamaterial units having the same or substantially the same refractive index are distributed over a zigzag half circumference.
  • the specific design is similar to the programming mode (such as OpenGL) when the computer draws a semi-circular, semi-elliptical and other smooth curves with square pixels. When the pixel is small relative to the curve, the curve is smooth, and when the pixel is relatively The curve shows jagged when the curve is large.
  • the volume of the artificial hole structure 212' and the medium filled in the artificial hole structure 212' can be designed. Two preferred embodiments are discussed in detail below.
  • each core layer 210' of the metamaterial panel 20' is composed of a plurality of metamaterial units, each of which includes a unit substrate 211' provided with an artificial hole structure 212'.
  • Unit substrate 21 ⁇ Polymers, ceramic materials, ferroelectric materials, ferrite materials, etc. can be used. Among them, the high molecular polymer is preferably a FR-4 or F4B material.
  • the artificial hole structure 212' may be formed on the unit substrate 211' by different processes corresponding to different unit substrates 211'. For example, when the unit substrate 211' is selected from a high molecular polymer, it may be drilled or punched by a drill press or The artificial hole structure 212' is formed by injection molding or the like. When the unit base material 211' is selected from ceramics, the artificial hole structure 212 can be formed by drilling, punching, or high-temperature sintering.
  • the artificial hole structure 212' can be filled with a medium.
  • the medium filled in the artificial hole structure 212' is air, and the refractive index of the air is inevitably smaller than the refractive index of the unit substrate 211', when the artificial hole structure The larger the 212' volume, the smaller the refractive index of the metamaterial unit in which the manhole structure 212' is located.
  • the arrangement of the artificial hole structure 212' disposed in the metamaterial unit in each core layer 210' is: the volume of the artificial hole structure 212' formed on the metamaterial unit is fed
  • the orthographic projection on each core layer 210' is a semicircular distribution of the center of the circle, wherein the volume of the artificial hole structure 212' formed on the metamaterial unit at the center of the circle is the smallest, and the formation of the material element is formed as the radius increases.
  • the volume of the artificial pore structure 212' is also increased, and the artificial pore structure 212' formed on the metamaterial unit having the same radius is the same volume.
  • the artificial hole structure 212' when the artificial hole structure 212' is filled with the same medium having a refractive index greater than that of the unit substrate 21, the larger the artificial hole structure 212' is at this time, the super-material unit occupied by the artificial hole structure 212' The refractive index is also larger, so that the arrangement of the artificial hole structure 212' disposed in the metamaterial unit at this time in each core layer 210' will be completely opposite to the arrangement of the air filled in the artificial hole structure 212'. .
  • Another embodiment of the present invention is different from the first preferred embodiment in that a plurality of artificial hole structures 212' having the same volume are present in each metamaterial unit, which simplifies the provision of artificial holes on the unit substrate 21 The process difficulty of structure 212'.
  • the distribution rule of all the artificial hole structures in the super material unit in the super-material unit in the preferred embodiment is the same as that in the first preferred embodiment, that is, divided into two. Case: (1) When the refractive index of the medium filled in all the artificial pore structures is smaller than the refractive index of the unit substrate, each core layer 210' includes a center of the orthographic projection of the feed 10 on each core layer 210'.
  • An artificial hole formed on a metamaterial unit at a center of a semicircular area The number of structures 212' is the smallest, and the number of the artificial hole structures 212' formed on the metamaterial units having the same radius is the same. As the radius increases, the artificial hole structure 212' formed on the metamaterial units at various points corresponding to the radius The number has also increased.
  • each core layer 210' includes A semi-circular area centered on the orthographic projection of the feed 10 on each core layer 210' and having the largest number of man-made hole structures 212' formed on the metamaterial unit at the center of the circle, having the same radius everywhere
  • the number of manhole structures 212' formed on the metamaterial unit is the same, and as the radius increases, the number of manhole structures 212' formed on the metamaterial units at various locations corresponding to the radius decreases.
  • the refractive index of each core layer 210' of the metamaterial panel 20' is centered on the orthographic projection of the feed 10 on each core layer 210', and the radius r varies according to the following rules. expression:
  • max represents the maximum refractive index value in each core layer 210'
  • d represents the total thickness of all core layers 210'
  • ss represents the feed source 10 to the core layer 210' closest to the feed position.
  • the distance, n(r) represents the refractive index value at the radius r in each core layer 210'.
  • each of the metamaterial grading layers 220' includes a sheet-like substrate layer 221, a sheet-like filling layer 223', and an air layer 222 disposed between the substrate layer 221' and the filling layer 223'. '.
  • the substrate layer 221 ' can be selected from a polymer, a ceramic material, a ferroelectric material, a ferrite material, or the like. Among them, the high molecular polymer is preferably a FR-4 or F4B material.
  • the refractive index profile within each graded layer 220' is uniform, and the index of refraction between the plurality of graded layers is different, in order to match the impedance of the air and core layer 210', typically by adjusting the layer of air 222'
  • the impedance is achieved by distance and by filling a filling layer 223' with a medium having a different refractive index, and the medium may be the same material as the substrate layer 22 or air, wherein
  • the metamaterial gradient layer 220' near the air has a refractive index closest to the air and gradually increases in refractive index toward the core layer 210'.
  • the refractive index in each of the graded layers 220' of the metamaterial panel 20' is uniformly distributed, and the variation of the refractive index distribution between the plurality of graded layers 220' is as follows:
  • the gradient layer is the outermost gradient layer.
  • the offset-feeding radar antenna of the present invention greatly increases the far-field power of the antenna by changing the refractive index distribution inside the super-material panel 20', thereby increasing the distance traveled by the antenna and increasing the distance.
  • the front-to-back ratio of the antenna makes the antenna more directional.
  • the invention adopts an offset-fed radar antenna, so that the radiation of the electromagnetic wave is no longer blocked by the feed 10, and the influence of the radiated electromagnetic wave on the feed 10 is also avoided.

Abstract

提供了一种偏馈式雷达天线，包括：馈源、超材料面板以及反射板。所述馈源位于所述超材料面板的另一侧且在超材料面板的非正对区域，所述超材料面板包括多个具有相同折射率分布的核心层，所述每一核心层包括多个超材料单元，所述超材料单元包括设置有人造金属微结构或人造孔结构的单元基材。所述偏馈式雷达天线通过改变材料面板内部的折射率分布情况，增强了天线远场功率，进而提升了天线传播的距离，同时增加了天线的前后比，使得天线更具方向性；所述偏馈式雷达天线的使用使得馈源对电磁波的辐射不再遮拦，同时也避免了辐射的电磁波对馈源的影响。

Description

偏馈式雷达天线
【技术领域】
本发明涉及雷达天线领域， 特别是涉及一种使用超材料的偏馈式雷达天线。 【背景技术】
雷达天线通过反射器将馈源辐射的球面波变为平面波， 从而实现定向接收 或者发射电磁波， 目前使用的反射器是抛物面形状， 馈源位于反射器的焦点附 近。
雷达天线的工作原理与光学反射镜相似， 现有的雷达抛物面天线如图 1 所 示， 包括溃源 1、 抛物面反射器 2和支架 3， 在抛物面反射器 2的焦点处放置有 发射或者接收电磁波的馈源 1， 利用抛物面反射器 2的聚焦特性， 由馈源 1发出 的球面波经抛物面反射器 2 反射后变换成平面波， 形成沿抛物面轴向辐射最强 的窄波束。
为了制造抛物反射面通常利用模具铸造成型或者采用数控机床进行加工的 方法。 第一种方法的工艺流程包括： 制作抛物面模具、 铸造成型抛物面和进行 抛物反射面的安装。 工艺比较复杂， 成本高， 而且抛物面的形状要比较准确才 能实现天线的定向传播， 所以对加工精度的要求也比较高。 第二种方法采用大 型数控机床进行抛物面的加工， 通过编辑程序， 控制数控机床中刀具所走路径， 从而切割出所需的抛物面形状。 这种方法切割很精确， 但是制造这种大型数控 机床比较困难， 而且成本比较高。
超材料是一种具有天然材料所不具备的超常物理性质的人工复合结构材 料。 超材料通过对微结构的有序排列， 可以改变超材料中每点的相对介电常数 和磁导率， 实现物质的折射率分布的非均匀性从而控制电磁波在材料中的传播 路径。
【发明内容】
本发明的目的在于克服现有技术中制造抛物面天线生产工艺复杂的问题， 提供一种偏馈式雷达天线， 该天线提出了一种结构简单的具有平面反射板的雷 达天线， 这种平面结构的天线具有抛物面天线可以定向接收或者发射电磁波的 优点， 同时避免了生产抛物面天线时的复杂工艺。
本发明解决其技术问题所采用的技术方案是： 提出一种偏馈式雷达天线， 所述天线包括： 馈源， 用于辐射电磁波； 超材料面板， 用于将所述馈源辐射出 的电磁波从球面电磁波转化为平面电磁波， 所述天线还包括紧贴于所述超材料 面板一侧的反射板， 用于将电磁波反射到超材料面板进行汇聚折射并向远处辐 射， 所述馈源位于所述超材料面板的另一侧且在超材料面板的非正对区域， 所 述超材料面板包括多个具有折射率相同分布的多个核心层， 所述每一核心层包 括多个超材料单元， 所述超材料单元包括单元基材以及人造金属微结构， 所述 超材料面板的每一核心层的折射率以所述馈源在每一核心层上的正投影为圆心 呈圆形分布， 且随着半径的增加折射率逐渐减小， 且半径相同处的折射率相同。
进一歩地， 所述超材料单元还包括第一填充层， 所述人造金属微结构位于 所述单元基材和第一填充层之间， 所述第一填充层内填充的材料包括空气、 人 造金属微结构以及与所述单元基材相同材料的介质。
进一歩地， 所述超材料面板还包括分布于所述核心层一侧的多个渐变层， 所述每一渐变层均包括片状的基板层、 片状的第二填充层以及设置在所述基板 层和填充层之间的空气层。
进一歩地， 所述第二填充层内填充的介质包括空气以及与所述基板层相同 材料的介质。
进一歩地， 所述第一基板层和第二基板层均由陶瓷材料、 环氧树脂、 聚四 氟乙烯、 FR-4复合材料或 F4B复合材料制得。
进一歩地， 所述超材料面板的每一核心层的折射率以所述馈源在每一核心 层上的正投影为圆心， 随着半径 r的变化规律如以下表达式：
.、
Figure imgf000004_0001
ss
n(r )― n ：
、 ) max 2d 式中《max表示所述每一核心层中的最大折射率值， d表示所有核心层的总厚 度， ss表示所述馈源到最靠近馈源位置的核心层的距离， n^表示所述多个核心 层内半径 r处折射率值。
进一歩地， 所述超材料面板的每一渐变层内的折射率均匀分布的， 且多个 渐变层间折射率分布的变化规律如以下表达式：
ητ = ( max ^ mm )m , 1=1、 2、 3、 …、 m， 其中 表示第 i层渐变层的折射率值， m表示渐变层的层数， 《mn表示所述 每一核心层内的最小折射率值， 《max表示所述每一核心层中的最大折射率值， 其 中第 m层渐变层与核心层靠近， 随着 m值的变小逐渐远离核心层， 第一层渐变 层为最外层渐变层。
进一歩地， 所述人造金属微结构为由至少一根金属丝组成对电磁场有响应 的平面结构或立体结构， 所述金属丝为铜丝或银丝。
进一歩地， 所述金属丝通过蚀刻、 电镀、 钻刻、 光刻、 电子刻或离子刻的 方法附着在所述单元基材上。
进一歩地， 所述人造金属微结构为在 "工"字形、 "工"字形的衍生形、 雪 花状或雪花状的衍生形任意一种。
进一歩地， 所述每一超材料单元上形成有一个人造孔结构， 所述人造孔结 构内填充有折射率小于单元基材折射率的介质， 且所有超材料单元内的人造孔 结构都填充相同材料的介质， 所述设置在超材料单元内的人造孔结构体积在每 一核心层内的排布规律为： 所述超材料单元上形成的人造孔结构体积以所述馈 源在每一核心层上的正投影为圆心呈半圆形分布， 随着半径的增大超材料单元 上形成的人造孔结构体积亦增大， 且具有相同半径处的超材料单元上形成的人 造孔结构体积相同。
进一歩地， 所述每一超材料单元上形成有一个人造孔结构， 所述人造孔结 构内填充有折射率大于单元基材折射率的介质， 且所有超材料单元内的人造孔 结构都填充相同材料的介质， 所述设置在超材料单元内的人造孔结构体积在每 一核心层内的排布规律为： 所述超材料单元上形成的人造孔结构体积以所述馈 源在每一核心层上的正投影为圆心呈半圆形分布， 随着半径的增大超材料单元 上形成的人造孔结构体积逐渐减小， 且具有相同半径处的超材料单元上形成的 人造孔结构体积相同。
进一歩地， 所述超材料单元上形成有数量不同、 体积相同的人造孔结构， 所述人造孔结构内填充有折射率小于单元基材折射率的介质， 且所有超材料单 元内的人造孔结构都填充相同材料的介质， 所述设置在超材料单元内的人造孔 结构数量在每一核心层内的排布规律为： 所述超材料单元上形成的人造孔结构 数量以所述馈源在每一核心层上的正投影为圆心呈半圆形分布， 随着半径的增 大超材料单元上形成的人造孔结构数量亦逐渐增加， 且具有相同半径处的超材 料单元上形成的人造孔结构数量相同。
进一歩地， 所述超材料单元上形成有数量不同、 体积相同的人造孔结构， 所述人造孔结构内填充有折射率大于单元基材折射率的介质， 且所有超材料单 元内的人造孔结构都填充相同材料的介质， 所述设置在超材料单元内的人造孔 结构数量在每一核心层内的排布规律为： 所述超材料单元上形成的人造孔结构 数量以所述馈源在每一核心层上的正投影为圆心呈半圆形分布， 随着半径的增 大超材料单元上形成的人造孔结构数量逐渐减小， 且具有相同半径处的超材料 单元上形成的人造孔结构数量相同。
本发明相对于现有技术， 具有以下有益效果： 一种偏馈式雷达天线， 平面 天线的结构简单， 通过利用超材料对电磁波进行汇聚的特性， 使得雷达天线不 依赖电磁波汇聚设备的形状， 省去了加工传统抛物面天线的复杂制造工艺， 同 时又可以实现传统抛物面天线定向接收或者发射电磁波的优点。 还有本发明采 用了偏馈式雷达天线， 使得馈源对电磁波的辐射不再遮拦， 同时也避免了辐射 的电磁波对馈源的影响。
【附图说明】 图 2是本发明第一实施例的一种偏馈式雷达天线示意图；
图 3是本发明第一实施例的一种偏馈式雷达天线示意图；
图 4是本发明第一实施例的所述超材料面板的结构示意图；
图 5是本发明第一实施例的所述核心层的结构示意图；
图 6是本发明第一实施例的所述核心层的结构示意图；
图 7是本发明第一实施例的所述超材料单元的结构示意图；
图 8是本发明第一实施例的所述渐变层结构示意图；
图 9是本发明第一实施例的核心层折射率变化示意图；
图 10是本发明第一实施例的核心层折射率变化示意图；
图 11是本发明第二实施例的一种偏馈式雷达天线示意图；
图 12是本发明第二实施例的一种偏馈式雷达天线示意图；
图 13是本发明第二实施例的所述超材料面板的结构示意图；
图 14是本发明第二实施例的所述核心层的结构示意图；
图 15是本发明第二实施例的所述超材料单元结构示意图；
图 16是本发明第二实施例的所述渐变层结构示意图。
【具体实施方式】
下面结合实施例及附图， 对本发明作进
方式不限于此。 图 2和图 3是本发明前馈式雷达天线的结构示意图， 该天线包括馈源 10、 超材料面板 20以及反射板 30，所述馈源 10和发射板 30分别位于所述超材料面 板 20的两侧， 反射板 30与超材料面板 20紧贴相连， 馈源 10所在点在所述超 材料面板 20上的正投影为超材料面板 20下底边的中点。
通常从馈源 10辐射的电磁波是球面电磁波， 但是球面电磁波的远场方向性 能不好， 对于远距离以球面电磁波为载体的信号传输有很大的局限性， 而且衰 减快， 本发明通过设计一具有电磁波汇聚功能的超材料面板 20 ， 该超材料面板 20将馈源 10辐射出来的大部分电磁波从球面电磁波转换为平面电磁波，且在通 过超材料面板 20的电磁波经过反射板 30反射后再次通过超材料面板 20折射汇 聚并辐射出去， 使得雷达天线的方向性更好， 天线主瓣能量密度更高， 能量更 大， 进而以该平面电磁波为载体的信号传输距离更远。
图 4是图 2所示的超材料面板 20的结构示意图， 超材料面板 20包括多个 核心层 210以及分布在靠近馈源一侧的多个渐变层 220，每一核心层 210均由多 个超材料单元组成， 所述超材料单元包括单元基材 211、 片状的第一填充层 213 以及设置在所述单元基材 211 和第一填充层 213 之间的多个人造金属微结构 212， 如图 6以及如图 7所示。 所述第一填充层 213内填充的材料可以是空气、 人造金属微结构以及与所述单元基材相同材料的介质， 比如， 当需要所述超材 料单元内的等效折射率变大时， 可以在第一填充层 213 内填充金属微结构或者 是填充具有较大折射率的介质； 当需要所述超材料单元内的等效折射率变小时， 可以在第一填充层 213内填充空气介质或者是不填充任何介质。 超材料面板 20 内的多个超材料核心层 210堆叠在一起， 且各个核心层 210之间等间距排列地 组装， 或两两片层之间直接前、 后表面相粘合地连接成一体。 具体实施时， 超 材料核心层的数目以及各个核心层之间的距离可依据需求来进行设计。 每个超 材料核心层 210 由多个超材料单元阵列形成， 整个超材料核心层 210可看作是 由多个超材料单元沿 X、 Y、 Ζ三个方向阵列排布而成， 如图 5所示。
所述超材料面板 20的多个核心层 210通过改变其内部的折射率分布以实现 通过所述超材料面板 20后的电磁波等相位辐射， 即实现从所述馈源 10辐射出 的球面电磁波转换为平面电磁波。 本发明中每个超材料核心层 210 的折射率分 布均相同， 这里仅对一个超材料核心层 210 的折射率分布规律进行详细描述。 通过对人造金属微结构 212的拓扑图案、 几何尺寸以及其在单元基材 211和第 一填充层 213上分布的设计， 使中间的核心层 210的折射率分布满足如下规律: 每一层核心层 210的折射率分布均相同， 每一核心层包括一个以馈源 10在每一 核心层 210 上的正投影为圆心的半圆形面域， 所述半圆形面域内圆心处的折射 率为最大值 ¾^且随着半径的增大逐渐减小， 相同半径处的折射率相同， 如图 10所示， 给出了折射率在 r方向上的变化图， 但应知本发明的折射率变化并不 以此为限。 本发明设计目的为： 使电磁波经过各超材料核心层 210 时， 电磁波 偏折角度被逐渐改变并最终平行辐射。 通过公式 Sm^=q* A«， 其中 为所需偏 折电磁波的角度、 Δ«为前后折射率变化差值， q为超材料功能层的厚度并通过 计算机仿真即可确定所需参数值并达到本发明设计目的。
图 9和图 10所示为超材料核心层折射率分布在半径 r上的变化视图。 作为 公知常识我们可知， 电磁波的折射率与 Λ ^成正比关系， 其中 μ为磁导率， ε为 介电常数， 当一束电磁波由一种介质传播到另外一种介质时， 电磁波会发生折 射， 当物质内部的折射率分布非均匀时， 电磁波就会向折射率比较大的位置偏 折， 因此， 设计超材料面板 20内核心层 210各点的折射率使其满足上述折射率 变化规律， 需要说明的是， 由于实际上超材料单元是一个立方体而非一个点， 因此上述半圆形面域只是近似描述， 实际上的折射率相同或基本相同的超材料 单元是在一个锯齿形半圆周上分布的。 其具体设计类似于计算机用方形像素点 绘制半圆形、 半椭圆形等平滑曲线时进行描点的编程模式 （例如 OpenGL) , 当 像素点相对于曲线很小时曲线显示为光滑， 而当像素点相对于曲线较大时曲线 显示有锯齿。
为使超材料面板 20的每一核心层 210实现图 9和图 10所示折射率的变化， 经过理论和实际证明， 可对所述人造金属微结构 212 的拓扑结构、 几何尺寸以 及其在单元基材 211和第一填充层 213上分布的设计， 单元基材 211采用介电 绝缘材料制成， 可以为陶瓷材料、 高分子材料、 铁电材料、 铁氧材料、 铁磁材 料等， 高分子材料例如可以是、 环氧树脂或聚四氟乙烯。 人造金属微结构 212 为以一定的几何形状附着在单元基材 211 上能够对电磁波有响应的金属线， 金 属线可以是剖面为圆柱状或者扁平状的铜线、 银线等， 一般采用铜， 因为铜丝 相对比较便宜， 当然金属线的剖面也可以为其他形状， 金属线通过蚀刻、 电镀、 钻刻、 光刻、 电子刻或离子刻等工艺附着在单元基材 211 上， 所述第一填充层 213可以填充不同材料的介质， 可以与单元基材 211相同的材料， 也可以是人造 金属微结构， 还可以是空气， 所述每一核心层 210 由多个超材料单元组成， 每 超材料单元都具有一个人造金属微结构， 每一个超材料单元都会对通过其中的 电磁波产生响应， 从而影响电磁波在其中的传输， 每个超材料单元的尺寸取决 于需要响应的电磁波， 通常为所需响应的电磁波波长的十分之一， 否则空间中 包含人造金属微结构 212的超材料单元所组成的排列在空间中不能被视为连续。
在单元基材 211 的选定的情况下， 通过调整人造金属微结构 212的形状、 尺寸及其在单元基材 211上的空间分布和在第一填充层 213填充不同折射率的 介质， 可以调整超材料上各处的等效介电常数及等效磁导率进而改变超材料各 处的等效折射率。 当人造金属微结构 212采用相同的几何形状时， 某处人造金 属微结构的尺寸越大， 则该处的等效介电常数越大， 折射率也越大。
本实施例采用的人造金属微结构 212 的图案为工字形的衍生图案， 由图 5 可知， 雪花状人造金属微结构 212的尺寸从以馈源 10在每一核心层 210上的正 投影为圆心， 向周围逐渐变小， 在圆心处， 雪花状的人造金属微结构 212 的尺 寸最大， 并且在相同半径处的雪花状人造金属微结构 212 的尺寸相同， 因此每 一核心层 210 的等效介电常数由圆心向四周逐渐变小， 圆心的等效介电常数最 大， 因而每一核心层 210 的折射率从圆心向四周逐渐变小， 圆心部分的折射率 最大。
上面结合附图对本发明的实施例进行了描述， 但是本发明并不局限于上述 的具体实施方式， 人造金属微结构 212的图案可以是二维、 也可以是三维结构， 不限于该实施例中使用的 "工"字形， 可以为 "工"字形的衍生结构， 可以是 在三维空间中各条边相互垂直的雪花状及雪花状的衍生结构， 也可以是其他的 几何形状， 其中不同的人造金属微结构 212可以是图案相同， 但是其设计尺寸 不同； 也可以是图案和设计尺寸均不相同， 只要满足由天线单元发出的电磁波 经过超材料面板 20传播后可以平行射出即可。 本发明实施例中， 所述超材料面板 20的每一核心层 210的折射率以以馈源 10在每一核心层 210上的正投影为圆心， 随着半径 r的变化规律如以下表达式：
Figure imgf000011_0001
式中《max表示所述每一核心层 210中的最大折射率值， d表示所有核心层 210 的总厚度， ss表示所述馈源 10到最靠近馈源位置的核心层 210的距离， 表 示所述每一核心层 210内半径 r处折射率值。
通常当电磁波从一种介质传输到另一种介质的时候， 由于阻抗不匹配的问 题， 会出现一部分电磁波反射， 这样影响电磁波的传输性能， 本发明中， 当从 馈源 10辐射出来的电磁波入射到超材料面板 20时同样会产生反射， 为了减少 反射对雷达天线的影响， 我们在超材料面板 20的核心层 210—侧设置多个超材 料渐变层 220， 如图 4所示。
如图 8所示， 每一超材料渐变层 220均包括片状的基板层 221、片状的第二 填充层 223以及设置在所述基板层 221和第二填充层 223之间的空气层 222。所 述基板层 221 可选用高分子聚合物、 陶瓷材料、 铁电材料、 铁氧材料等。 其中 高分子聚合物优选 FR-4或 F4B材料。多个超材料渐变层 220之间的折射率是不 同的， 为了匹配空气与核心层 210的阻抗， 通常是通过调整所述空气层 222的 宽度和通过在第二填充层 223 内填充含有不同折射率的介质来实现阻抗匹配， 该介质也可以是与基板层 221 相同的材料， 也可以是空气， 其中靠近空气的超 材料渐变层 220的折射率最接近空气且朝核心层 210方向折射率逐渐增加。
本发明中实施例中， 所述超材料面板 20的每一渐变层内 220的折射率均匀 分布的， 且多个渐变层 220间折射率分布的变化规律如以下表达式：
ητ = ( max ^ mm )m , 1=1、 2、 3、 …、 m， 其中 表示第 i层渐变层 220的折射率值， m表示渐变层 220的层数，《mn表 示所述每一核心层 210内的最小折射率值， 《max表示所述每一核心层 210中的最 大折射率值， 其中第 m层渐变层 220与核心层 210靠近， 随着 m值的变小逐渐 远离核心层 210， 第 1层渐变层为最外层渐变层。 综上所述， 本发明的一种偏馈式雷达天线通过改变超材料面板 20内部的折 射率分布情况， 使得天线远场功率大大地增强了， 进而提升了天线传播的距离， 同时增加了天线的前后比， 使得天线更具方向性； 还有本发明采用了偏馈式雷 达天线， 使得馈源对电磁波的辐射不再遮拦， 同时也避免了辐射的电磁波对馈 源的影响。 图 11和图 12是本发明第二实施例的偏馈式雷达天线的结构示意图， 该天 线包括馈源 10、 超材料面板 20'以及反射板 30， 所述馈源 10和发射板 30分别 位于所述超材料面板 20'的两侧，反射板 30与超材料面板 20'紧贴相连，馈源 10 所在点在所述超材料面板 20'上的正投影为超材料面板 20'下底边的中点。
通常从馈源 10辐射的电磁波是球面电磁波， 但是球面电磁波的远场方向性 能不好， 对于远距离以球面电磁波为载体的信号传输有很大的局限性， 而且衰 减快， 本发明通过设计一具有电磁波汇聚功能的超材料面板 20' ， 该超材料面 板 20'将馈源 10辐射出来的大部分电磁波从球面电磁波转换为平面电磁波， 且 在通过超材料面板 20'的电磁波经过反射板 30反射后再次通过超材料面板 20' 折射汇聚并辐射出去， 使得雷达天线的方向性更好， 天线主瓣能量密度更高， 能量更大， 进而以该平面电磁波为载体的信号传输距离更远。
图 13所示，所述超材料面板 20'包括多个具有相同折射率分布的核心层 210' 以及分布在靠近馈源 10—侧的多个渐变层 220'，所述核心层 210'也就是超材料 面板 10的功能层， 由多个超材料单元组成， 由于超材料面板 20 ' 需对电磁波产 生连续响应， 因此超材料单元尺寸应小于所需响应电磁波波长的五分之一， 本 实施例优选为电磁波波长的十分之一。 如图 15所示， 所述超材料单元包括设置 有一个或多个人造孔结构 212'的单元基材 211 '。 这样设置有人造孔结构 212'的 每一核心层 210'叠加在一起就构成超材料面板 20'的功能层， 如图 16所示。
所述超材料面板 20'的多个核心层 210'通过改变其内部的折射率分布以实现 通过所述超材料面板 20'后的电磁波等相位辐射， 即实现从所述馈源 10辐射出 的球面电磁波转换为平面电磁波。本实施例中每一核心层 210' 的折射率分布均 相同， 且与上一实施例中的核心层 210 ' 的折射率分布相同。这里仅对一个超材 料核心层 210 ' 的折射率分布规律进行详细描述。 通过对人造孔结构 212' 的体 积、 人造孔结构 212' 内填充的介质以及人造孔结构 212' 的密度的设计使得每 一核心层 210' 的折射率分布如图 10所示。超材料面板 20 ' 的每一核心层 210' 包括一个以馈源 10在每一核心层 210' 上的正投影为圆心的半圆形面域， 半圆 形面域的圆心处折射率最大为 nmax， 具有相同半径处折射率相同， 半径越大， 折 射率越小。 图 10中给出折射率变化图， 但应知本发明的折射率变化并不以此为 限。 本发明设计目的为： 使电磁波经过各核心层 210'时， 电磁波偏折角度被逐 渐改变并最终平行辐射。 通过公式 Sm^=q* A«， 其中 为所需偏折电磁波的角 度、 ^为前后折射率变化差值， q为超材料功能层的厚度并通过计算机仿真即 可确定所需参数值并达到本发明设计目的。
图 9为图 10所示超材料核心层折射率分布在 r方向上的视图。 作为公知常 识我们可知， 电磁波的折射率与 Λ ^成正比关系， 其中 μ为磁导率， ε为介电常 数， 当一束电磁波由一种介质传播到另外一种介质时， 电磁波会发生折射， 当 物质内部的折射率分布非均匀时， 电磁波就会向折射率比较大的位置偏折， 因 此， 设计超材料面板 20' 各点的折射率使其满足上述折射率变化规律， 需要说 明的是， 由于实际上超材料单元是一个立方体而非一个点， 因此上述半圆形面 域只是近似描述， 实际上的折射率相同或基本相同的超材料单元是在一个锯齿 形半圆周上分布的。 其具体设计类似于计算机用方形像素点绘制半圆形、 半椭 圆形等平滑曲线时进行描点的编程模式 （例如 OpenGL) , 当像素点相对于曲线 很小时曲线显示为光滑， 而当像素点相对于曲线较大时曲线显示有锯齿。
为使功能层实现图 9和图 10所示折射率的变化， 可对人造孔结构 212'的体 积、 人造孔结构 212'内填充的介质进行设计。 下面详细论述两种较佳实施方式。
如图 14所示， 超材料面板 20'的每一核心层 210'由多个超材料单元组成， 每一超材料单元包括设置有一个人造孔结构 212'的单元基材 211 '。单元基材 21Γ 可选用高分子聚合物、 陶瓷材料、 铁电材料、 铁氧材料等。 其中高分子聚合物 优选 FR-4或 F4B材料。对应不同的单元基材 211 '可采用不同的工艺在单元基材 211 '上形成人造孔结构 212'， 例如当单元基材 211 '选用高分子聚合物时， 可通 过钻床钻孔、 冲压成型或者注塑成型等方式形成人造孔结构 212'， 当单元基材 211 '选用陶瓷时则可通过钻床钻孔、冲压成型或者高温烧结等方式形成人造孔结 构 212，。
人造孔结构 212'内可填充介质， 本较佳实施方式中， 人造孔结构 212'内填 充的介质均为空气， 而空气的折射率必然小于单元基材 211 '的折射率， 当人造 孔结构 212'体积越大时， 人造孔结构 212'所在的超材料单元的折射率则越小。 本较佳实施方式中， 设置在超材料单元内的人造孔结构 212'在每一核心层 210' 内的排布规律为： 所述超材料单元上形成的人造孔结构 212'体积以馈源 10在每 一核心层 210'上的正投影为圆心呈半圆形分布， 其中圆心处的超材料单元上形 成的人造孔结构 212'的体积最小， 随着半径的增大超材料单元上形成的人造孔 结构 212'体积亦增大，且具有相同半径处的超材料单元上形成的人造孔结构 212' 体积相同。 可以想象地， 当人造孔结构 212'内填充有折射率大于单元基材 21Γ 的同种介质时， 则此时人造孔结构 212'体积越大， 人造孔结构 212'所占据的超 材料单元的折射率亦越大， 因此此时设置在超材料单元内的人造孔结构 212'在 每一核心层 210'内的排布规律将与人造孔结构 212'内填充为空气的排布规律完 全相反。
本发明的另一实施例， 与第一较佳实施方式的不同点在于， 每一超材料单 元中存在多个体积相同的人造孔结构 212'， 这样能简化在单元基材 21Γ上设置 人造孔结构 212'的工艺难度。 与第一较佳实施方式相同的地方在于， 本较佳实 施方式中每一超材料单元中所有人造孔结构占超材料单元的体积的分布规律与 第一较佳实施方式相同， 即分为两种情况： （1 ) 所有人造孔结构内填充的介质 折射率小于单元基材折射率时， 每一核心层 210'包括一个以馈源 10在每一核心 层 210'上的正投影为圆心的半圆形面域且圆心处的超材料单元上形成的人造孔 结构 212'的数量最少， 具有相同半径的超材料单元上形成的人造孔结构 212'的 数量相同， 随着半径的增大、 对应半径的各处的超材料单元上形成的人造孔结 构 212'的数量亦增多。 本较佳实施方式即为此种情况且所有人造孔结构 2内填 充介质为空气； （2) 所有人造孔结构 212'内填充的介质折射率大于基板折射率 时，每一核心层 210'包括一个以馈源 10在每一核心层 210'上的正投影为圆心的 半圆形面域且圆心处的超材料单元上形成的人造孔结构 212'的数量最多， 具有 相同半径的各处的超材料单元上形成的人造孔结构 212'的数量相同， 随着半径 的增大、 对应半径的各处的超材料单元上形成的人造孔结构 212'的数量减少。
本发明实施例中，所述超材料面板 20'的每一核心层 210'的折射率以馈源 10 在每一核心层 210' 上的正投影为圆心， 随着半径 r的变化规律如以下表达式：
.、
Figure imgf000015_0001
- ss
n(r)― n ：
、 ) max 2d
式中《max表示所述每一核心层 210'中的最大折射率值， d表示所有核心层 210'的总厚度， ss表示所述馈源 10到最靠近馈源位置的核心层 210'的距离， n(r) 表示所述每一核心层 210'内半径 r处折射率值。
通常当电磁波从一种介质传输到另一种介质的时候， 由于阻抗不匹配的问 题， 会出现一部分电磁波反射， 这样影响电磁波的传输性能， 本发明中， 当从 馈源 10辐射出来的电磁波入射到超材料面板 20'时同样会产生反射， 为了减少 反射对雷达天线的影响，我们在超材料面板 20'的核心层 210'—侧堆成设置多个 超材料渐变层 220'， 如图 13所示。
如图 16所示， 每一超材料渐变层 220'均包括片状的基板层 221、 片状的填 充层 223'以及设置在所述基板层 221 '和填充层 223'之间的空气层 222'。 基板层 221 '可选用高分子聚合物、 陶瓷材料、 铁电材料、 铁氧材料等。 其中高分子聚合 物优选 FR-4或 F4B材料。每一渐变层 220'内的折射率分布是均匀的， 多个渐变 层之间的折射率是不同的， 为了匹配空气与核心层 210'的阻抗， 通常是通过调 整所述空气层 222'的距离和通过在填充层 223'内填充含有不同折射率的介质来 实现阻抗匹配， 该介质也可以是与基板层 22Γ相同的材料也可以是空气， 其中 靠近空气的超材料渐变层 220'的折射率最接近空气且朝核心层 210'方向折射率 逐渐增加。
本发明中实施例中，所述超材料面板 20'的每一渐变层 220'内的折射率均匀 分布的， 且多个渐变层 220'间折射率分布的变化规律如以下表达式：
ητ = ( max ^ mm )m , 1=1、 2、 3、 …、 m， 其中 表示第 i层渐变层的折射率值， m表示渐变层的层数， 《mn表示所述 每一核心层内的最小折射率值， 《max表示所述每一核心层中的最大折射率值， 其 中第 m层渐变层与核心层靠近， 随着 m值的变小逐渐远离核心层， 第一层渐变 层为最外层渐变层。
综上所述， 本发明的一种偏馈式雷达天线通过改变超材料面板 20'内部的折 射率分布情况， 使得天线远场功率大大地增强了， 进而提升了天线传播的距离， 同时增加了天线的前后比， 使得天线更具方向性； 本发明采用了偏馈式雷达天 线， 使得馈源 10对电磁波的辐射不再遮拦， 同时也避免了辐射的电磁波对馈源 10的影响。
上述实施例为本发明较佳的实施方式， 但本发明的实施方式并不受上述实 施例的限制， 其他的任何未违背本发明的精神实质与原理下所作的改变、 修饰、 替代、 组合、 简化， 均应为等效的置换方式， 都包含在本发明的保护范围之内。

Claims

权 利 要求
1、 一种偏馈式雷达天线， 所述天线包括： 馈源， 用于辐射电磁波； 超材料 面板， 用于将所述馈源辐射出的电磁波从球面电磁波转化为平面电磁波， 其特 征在于， 所述天线还包括紧贴于所述超材料面板一侧的反射板， 用于将电磁波 反射到超材料面板进行汇聚折射并向远处辐射， 所述馈源位于所述超材料面板 的另一侧且在超材料面板的非正对区域， 所述超材料面板包括多个具有折射率 相同分布的多个核心层， 所述每一核心层包括多个超材料单元， 所述超材料单 元包括单元基材以及人造金属微结构， 所述超材料面板的每一核心层的折射率 以所述馈源在每一核心层上的正投影为圆心呈圆形分布， 且随着半径的增加折 射率逐渐减小， 且半径相同处的折射率相同。
2、 根据权利要求 1所述的雷达天线， 其特征在于， 所述超材料单元还包括 第一填充层， 所述人造金属微结构位于所述单元基材和第一填充层之间， 所述 第一填充层内填充的材料包括空气、 人造金属微结构以及与所述单元基材相同 材料的介质。
3、 根据权利要求 1所述的雷达天线， 其特征在于， 所述超材料面板还包括 分布于所述核心层一侧的多个渐变层， 所述每一渐变层均包括片状的基板层、 片状的第二填充层以及设置在所述基板层和填充层之间的空气层。
4、 根据权利要求 3所述的雷达天线， 其特征在于， 所述第二填充层内填充 的介质包括空气以及与所述基板层相同材料的介质。
5、 根据权利要求 3所述的雷达天线， 其特征在于， 所述第一基板层和第二 基板层均由陶瓷材料、 环氧树脂、 聚四氟乙烯、 FR-4复合材料或 F4B复合材料 制得。
6、 根据权利要求 1所述的雷达天线， 其特征在于， 所述超材料面板的每一 核心层的折射率以所述馈源在每一核心层上的正投影为圆心，随着半径 r的变化 规律如以下表达式：
.、
Figure imgf000018_0001
ss
n(r )― n ：
、 ) max 2d 式中《max表示所述每一核心层中的最大折射率值， d表示所有核心层的总厚 度， ss表示所述馈源到最靠近馈源位置的核心层的距离， n^表示所述多个核心 层内半径 r处折射率值。
7、 根据权利要求 1所述的雷达天线， 其特征在于， 所述超材料面板的每一 渐变层内的折射率均匀分布的， 且多个渐变层间折射率分布的变化规律如以下 表达式：
ητ = ( max ^ mm )m , 1=1、 2、 3、 …、 m， 其中 表示第 i层渐变层的折射率值， m表示渐变层的层数， 《mn表示所述 每一核心层内的最小折射率值， 《max表示所述每一核心层中的最大折射率值， 其 中第 m层渐变层与核心层靠近， 随着 m值的变小逐渐远离核心层， 第一层渐变 层为最外层渐变层。
8、 根据权利要求 1所述的雷达天线， 其特征在于， 所述人造金属微结构为 由至少一根金属丝组成对电磁场有响应的平面结构或立体结构， 所述金属丝为 铜丝或银丝。
9、 根据权利要求 8所述的雷达天线， 其特征在于， 所述金属丝通过蚀刻、 电镀、 钻刻、 光刻、 电子刻或离子刻的方法附着在所述单元基材上。
10、 根据权利要求 8所述的雷达天线， 其特征在于， 所述人造金属微结构 为在 "工"字形、 "工"字形的衍生形、 雪花状或雪花状的衍生形任意一种。
11、 根据权利要求 1 所述的一种偏馈式雷达天线， 其特征在于， 所述每一 超材料单元上形成有一个人造孔结构， 所述人造孔结构内填充有折射率小于单 元基材折射率的介质， 且所有超材料单元内的人造孔结构都填充相同材料的介 质， 所述设置在超材料单元内的人造孔结构体积在每一核心层内的排布规律为： 所述超材料单元上形成的人造孔结构体积以所述馈源在每一核心层上的正投影 为圆心呈半圆形分布， 随着半径的增大超材料单元上形成的人造孔结构体积亦 增大， 且具有相同半径处的超材料单元上形成的人造孔结构体积相同。
12、 根据权利要求 1 所述的一种偏馈式雷达天线， 其特征在于， 所述每一 超材料单元上形成有一个人造孔结构， 所述人造孔结构内填充有折射率大于单 元基材折射率的介质， 且所有超材料单元内的人造孔结构都填充相同材料的介 质， 所述设置在超材料单元内的人造孔结构体积在每一核心层内的排布规律为： 所述超材料单元上形成的人造孔结构体积以所述馈源在每一核心层上的正投影 为圆心呈半圆形分布， 随着半径的增大超材料单元上形成的人造孔结构体积逐 渐减小， 且具有相同半径处的超材料单元上形成的人造孔结构体积相同。
13、 根据权利要求 1 所述的一种偏馈式雷达天线， 其特征在于， 所述超材 料单元上形成有数量不同、 体积相同的人造孔结构， 所述人造孔结构内填充有 折射率小于单元基材折射率的介质， 且所有超材料单元内的人造孔结构都填充 相同材料的介质， 所述设置在超材料单元内的人造孔结构数量在每一核心层内 的排布规律为： 所述超材料单元上形成的人造孔结构数量以所述馈源在每一核 心层上的正投影为圆心呈半圆形分布， 随着半径的增大超材料单元上形成的人 造孔结构数量亦逐渐增加， 且具有相同半径处的超材料单元上形成的人造孔结 构数量相同。
14、 根据权利要求 1 所述的一种偏馈式雷达天线， 其特征在于， 所述超材 料单元上形成有数量不同、 体积相同的人造孔结构， 所述人造孔结构内填充有 折射率大于单元基材折射率的介质， 且所有超材料单元内的人造孔结构都填充 相同材料的介质， 所述设置在超材料单元内的人造孔结构数量在每一核心层内 的排布规律为： 所述超材料单元上形成的人造孔结构数量以所述馈源在每一核 心层上的正投影为圆心呈半圆形分布， 随着半径的增大超材料单元上形成的人 造孔结构数量逐渐减小， 且具有相同半径处的超材料单元上形成的人造孔结构 数量相同。
PCT/CN2011/083010 2011-07-26 2011-11-28 偏馈式雷达天线 WO2013013470A1 (zh)

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CN101404355A (zh) * 2008-10-31 2009-04-08 浙江大学 利用环状金属对单元结构天线罩的高指向天线
CN101587990A (zh) * 2009-07-01 2009-11-25 东南大学 基于人工电磁材料的宽带圆柱形透镜天线
CN101867094A (zh) * 2010-05-02 2010-10-20 兰州大学 一种聚焦平板天线

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101404355A (zh) * 2008-10-31 2009-04-08 浙江大学 利用环状金属对单元结构天线罩的高指向天线
CN101587990A (zh) * 2009-07-01 2009-11-25 东南大学 基于人工电磁材料的宽带圆柱形透镜天线
CN101867094A (zh) * 2010-05-02 2010-10-20 兰州大学 一种聚焦平板天线

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