Dual circularly polarized 3D printed multi-beam luneberg lens antenna

Abstract

The application discloses a kind of dual circular polarized 3D printing multi-beam Luneberg lens antenna, using 3D printing metamaterial technology, including: Luneberg lens and feed antenna;Luneberg lens includes M concentrically arranged spherical layers;Each spherical layer includes a plurality of units with corresponding equivalent refractive index;Unit is composed of asymmetric dielectric rod mutually orthogonal in x, y, z three directions;Luneberg lens with asymmetric cross structure is different in response to incident horizontal polarization and vertical polarization, so that Luneberg lens realizes the conversion of dual linear polarization to dual circular polarization;Feed antenna is set at 45° polarization angle relative to the x axis of Luneberg lens;Feed antenna includes: a plurality of electromagnetic dipole antenna radiation structures, and each electromagnetic dipole antenna radiation structure introduces orthogonally arranged first feed port and second feed port.By switching the corresponding feed port, the polarization mode of the finally generated left-handed circular polarization or right-handed circular polarization can be easily changed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lens antennas, and particularly relates to a double circularly polarized 3D printing multi-beam Luneberg lens antenna. BACKGROUND

[0002] In the field of modern communication technology, the performance of an antenna system is of great importance. Antennas with multiple beams, wide-angle scanning and high gain are highly sought after. In order to meet these requirements, various types of antennas have been researched and developed, including phased array antennas, reflector antennas and lens antennas. Phased array antennas can achieve flexible beam number and fast beam scanning, but they are too expensive to be used for large-scale deployment. Reflector antennas are simple in structure, but have high maintenance costs and unreliable mechanical positioning characteristics. Lens antennas have the advantages of easy manufacturing, small size and low cost. Therefore, lens antennas have been widely used in satellite communication, radar systems and millimeter waves. Among them, the Luneberg lens is a classic lens antenna.

[0003] The existing Luneberg lens mainly has the following processes:

[0004] Traditional layered structure

[0005] This technology divides the Luneberg lens into an onion structure through various layering methods, and uses different dielectric materials to fill each layer. This technology requires multiple dielectric materials at the same time, which undoubtedly has a high cost. Moreover, due to process problems, there will inevitably be gaps between layers, which will bring about large electromagnetic loss. This is an unfavorable factor for radiation performance. Even if the gap can be reduced by improving the process, it will also introduce a higher cost.

[0006] Flat plate type Luneberg lens

[0007] The flat plate type Luneberg lens realizes the function of the refractive index gradient of the Luneberg lens by punching holes or adding columns on the flat plate and using the periodicity of the structure and the size change of the holes or columns. This technology can achieve a wide frequency band, but the bandwidth performance may still be limited compared to the spherical Luneberg lens. Moreover, due to the flat plate structure, this technology is limited to two-dimensional planes.

[0008] 3D printing metamaterial Luneberg lens

[0009] A 3D-printed metamaterial Luneberg lens is a lens manufactured using 3D printing technology. This lens uses metamaterials to achieve the function of a traditional Luneberg lens. Metamaterials are artificially designed materials with special electromagnetic properties that can achieve properties that do not exist in nature. The 3D-printed metamaterial Luneberg lens has the required refractive index distribution within a specific frequency band by precisely designing the unit structure of the metamaterial. 3D printing technology allows the precise manufacturing of these complex structures, enabling complex geometries and refractive index distributions that are difficult to achieve with traditional methods. The Luneberg lens designed by this technology is often spherical, and the unit uses a symmetric structure. The polarization mode of this structure of Luneberg lens is only dependent on the feed antenna. SUMMARY

[0010] To solve the above problems existing in the prior art, the present application provides a dual circularly polarized 3D-printed multi-beam Luneberg lens antenna. The technical problem to be solved by the present application is solved by the following technical scheme:

[0011] The present application provides a dual circularly polarized 3D-printed multi-beam Luneberg lens antenna, comprising:

[0012] a Luneberg lens and a feed antenna; wherein,

[0013] The Luneberg lens comprises M concentrically arranged spherical layers; wherein M is a positive integer, each spherical layer has the same thickness and comprises a plurality of units with corresponding equivalent refractive indices; the unit is composed of dielectric rods orthogonal to each other in x, y and z directions; the size of the dielectric rods in x and z directions is the same, the size of the dielectric rods in y direction is smaller than that in x direction, and the equivalent refractive index of the corresponding unit is controlled by adjusting the size of the dielectric rods in the unit; for each unit in each spherical layer, the unit is connected in structure with the surrounding adjacent units;

[0014] The feed antenna is arranged at a 45° polarization angle relative to the x-axis of the Luneberg lens;

[0015] The feed antenna comprises a plurality of electromagnetic dipole antenna radiation structures, each electromagnetic dipole antenna radiation structure introduces a first feed port and a second feed port arranged orthogonally.

[0016] In an embodiment of the present application, the metamaterial comprises photosensitive resin.

[0017] In an embodiment of the present application, the refractive index of each spherical layer in the Luneberg lens gradually increases from 1 to

[0018] In an embodiment of the present application, M is 13.

[0019] In an embodiment of the present application, the size of the medium rod in the y direction in the unit is half of the size of the medium rod in the x and z directions.

[0020] In an embodiment of the present application, the geometric dimensions of the length, width and height of the unit are all not greater than one fifth of the wavelength of the incident electromagnetic wave.

[0021] In an embodiment of the present application, the number M of layers of the Luneberg lens is determined based on a first formula; the first formula is as follows:

[0022]

[0023] wherein N represents the number of units through which the incident electromagnetic wave passes, ni represents the equivalent refractive index of the i-th unit through which the x-polarized incident electromagnetic wave passes, ni represents the equivalent refractive index of the i-th unit through which the y-polarized incident electromagnetic wave passes, I represents the geometric dimension of the height of the unit, and λ0 represents the free space wavelength at 15 GHz.

[0024] In an embodiment of the present application, the electromagnetic dipole antenna radiation structure comprises:

[0025] a metal patch radiation layer, a first dielectric layer, four metal columns, a metal ground plate, a coupling slot, a second dielectric layer, a first feeding port, a third dielectric layer and a second feeding port; wherein,

[0026] the metal patch radiation layer, the first dielectric layer, the metal ground plate, the second dielectric layer and the third dielectric layer are sequentially stacked from top to bottom;

[0027] the metal patch radiation layer and the metal ground plate are connected by four vertical metal through holes penetrating the first dielectric layer;

[0028] the four metal columns are vertically arranged in the first dielectric layer, a first end of the four metal columns is connected with the metal patch radiation layer, and a second end of the four metal columns is connected with the metal ground plate;

[0029] the coupling slot is arranged on the metal ground plate by etching;

[0030] the first feeding port is arranged on the upper surface of the third dielectric layer;

[0031] the second feeding port is arranged on the lower surface of the third dielectric layer.

[0032] In an embodiment of the present application, the metal patch radiation layer comprises: four metal radiation patches; wherein each metal radiation patch adopts a symmetric slot design.

[0033] In one embodiment of the present application, the coupling slot comprises two I-shaped coupling slots arranged orthogonally.

[0034] Advantages of the present application:

[0035] In the scheme provided by the present application, the Luneberg lens with the asymmetric cross structure has different responses to the incident horizontal polarization and vertical polarization, so that the Luneberg lens has the function of polarization conversion, and realizes the conversion from dual linear polarization to dual circular polarization. The asymmetric structure is convenient to manufacture, and the finally formed Luneberg lens structure is stable, and the spherical structure avoids the disadvantages of large loss, high cost and dimensional limitation caused by the traditional layered structure and flat plate structure. The feed antenna as a feed source adopts a plurality of electromagnetic dipole antenna radiation structures, each electromagnetic dipole antenna radiation structure introduces a first feed port and a second feed port arranged orthogonally, and only by switching the corresponding feed port, the polarization mode of left-handed circular polarization or right-handed circular polarization generated finally can be easily changed. On the basis of retaining the original excellent properties of high gain, wide band and low cost of the traditional Luneberg lens, the function of polarization conversion is realized. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A physical schematic diagram of a dual circular polarization 3D printing multi-beam Luneberg lens antenna provided by an embodiment of the present application;

[0037] Figure 2 A schematic diagram of discretizing a Luneberg lens into a plurality of units provided by an embodiment of the present application;

[0038] Figure 3 A structure schematic diagram of a unit in a Luneberg lens provided by an embodiment of the present application;

[0039] Figure 4 A structure schematic diagram of a unit in a Luneberg lens provided by an embodiment of the present application;

[0040] Figure 5 A structure schematic diagram of a Luneberg lens provided by an embodiment of the present application;

[0041] Figure 6 A relationship diagram between the equivalent refractive index of a unit in a Luneberg lens provided by an embodiment of the present application and the normalized unit size ratio;

[0042] Figure 7 A relationship diagram between the equivalent refractive index of a unit in a Luneberg lens provided by an embodiment of the present application and the frequency;

[0043] Figure 8 A simulation diagram of the axial ratio corresponding to a Luneberg lens with different layer models provided by an embodiment of the present application;

[0044] Figure 9 A front view, a top view and a bottom view of a feed antenna provided by an embodiment of the present application;

[0045] Figure 10 A structural explosion schematic diagram of a feed antenna provided by an embodiment of the present application;

[0046] Figure 11 A simulation and test result diagram of reflection coefficients of a feed antenna provided by an embodiment of the present application in the case of having or not having a lens;

[0047] Figure 12 A schematic diagram of reflection coefficients of different ports and isolation degrees between the ports in a feed antenna provided by an embodiment of the present application;

[0048] Figure 13 A simulation and test result diagram of an axial ratio and gain in a microwave darkroom of a feed antenna provided by an embodiment of the present application;

[0049] Figure 14 A left-handed circular polarization and a right-handed circular polarization corresponding to a test and simulation radiation pattern of a dual-circularly-polarized 3D-printed multi-beam dragon lens antenna provided by an embodiment of the present application.

[0050] Reference signs

[0051] 1-first feed port of a first electromagnetic dipole antenna radiation structure, 2-second feed port of the first electromagnetic dipole antenna radiation structure, 3-first feed port of a second electromagnetic dipole antenna radiation structure, 4-second feed port of the second electromagnetic dipole antenna radiation structure, 5-first feed port of a third electromagnetic dipole antenna radiation structure, 6-second feed port of the third electromagnetic dipole antenna radiation structure, 7-first feed port of a fourth electromagnetic dipole antenna radiation structure, 8-second feed port of the fourth electromagnetic dipole antenna radiation structure, 9-first feed port of a fifth electromagnetic dipole antenna radiation structure, 10-second feed port of the fifth electromagnetic dipole antenna radiation structure, 11-metal patch radiation layer, 12-first dielectric layer, 13-four metal columns, 14-metal ground plate, 15-coupling slot, 16-second dielectric layer, 17-third dielectric layer, 18-first feed port, 19-second feed port. DETAILED DESCRIPTION

[0052] The present application will be further described below in conjunction with specific embodiments, but the embodiments of the present application are not limited thereto.

[0053] An embodiment of the present application provides a dual-circularly-polarized 3D-printed multi-beam dragon lens antenna, as shown in Figure 1As shown, a 3D printing metamaterial technology is adopted, including:

[0054] a dragon lens and a feed antenna; wherein,

[0055] The dragon lens comprises M concentrically arranged spherical layers; wherein, M is a positive integer, each spherical layer has the same thickness and comprises a plurality of units with corresponding equivalent refractive indexes; the units are composed of dielectric rods orthogonal to each other in x, y and z directions; the dielectric rods in x and z directions have the same size, the dielectric rods in y direction have a size smaller than that in x direction, the equivalent refractive index of the corresponding unit is controlled by adjusting the size of the dielectric rods in the unit; for each unit in each spherical layer, the unit is connected in structure with the surrounding adjacent units;

[0056] The feed antenna is arranged at a 45° polarization angle relative to the x axis of the dragon lens;

[0057] The feed antenna can comprise: a plurality of electromagnetic dipole antenna radiation structures, each electromagnetic dipole antenna radiation structure introduces a first feed port and a second feed port arranged orthogonally.

[0058] The double circularly polarized 3D printing multi-beam dragon lens antenna provided by the embodiment of the application can specifically comprise: a novel spherical double circularly polarized dragon lens with polarization conversion function and a feed antenna composed of a double linearly polarized electromagnetic dipole patch antenna.

[0059] Specifically, the metamaterial can comprise a photosensitive resin.

[0060] The progress of 3D printing technology provides an economical and efficient method for manufacturing complex three-dimensional structures. This technology has been widely used in the production of metamaterials, especially in the development of dragon lenses. The dragon lens is discretized into small units, the units are filled with 3D printed metamaterial structures, and the medium filling rate of the units is modified to control the equivalent refractive index, thereby manufacturing the dragon lens. This method can accurately control the refractive index at different positions of the lens, which is similar to the continuously changing refractive index.

[0061] For ease of understanding, the dragon lens and the feed antenna in the double circularly polarized 3D printing multi-beam dragon lens antenna provided by the embodiment of the application are introduced in detail respectively.

[0062] Dragon lens

[0063] The dragon lens, as Figure 2As shown, the lens can include M concentrically arranged spherical layers; wherein M is a positive integer, each spherical layer has the same thickness and includes a plurality of units having a corresponding equivalent refractive index; the unit is composed of asymmetric medium rods that are orthogonal to each other in the x, y, z three directions; the equivalent refractive index of the corresponding unit is controlled by adjusting the size of the medium rod in the unit; for each unit in each spherical layer, the unit is structurally connected with the surrounding adjacent units.

[0064] In the Luneburg lens, the equivalent refractive index distribution satisfies the following formula:

[0065]

[0066] Wherein, r represents the normalized radius, and n represents the equivalent refractive index.

[0067] Specifically, the refractive index of each spherical layer in the Luneburg lens gradually increases from 1 to 2 along the direction from the outside of the Luneburg lens to the center of the sphere.

[0068] In order to realize the gradient refractive index, the spherical Luneburg lens is discretized into concentric spherical layers with the same thickness. Then each layer is discretized into smaller units, as shown in Figure 2 However, with the increase of the number of layers of the Luneburg lens, the improvement of its radiation characteristics becomes less and less significant. Therefore, considering various factors comprehensively, the Luneburg lens in the embodiment of the present application is constructed as a 13-layer structure, that is, M is 13, and each layer is filled with units having a corresponding equivalent refractive index.

[0069] The structure diagram of the unit in the Luneburg lens is shown in Figure 3 As shown, the geometric dimensions of the length, width and height of the unit are not greater than one fifth of the wavelength of the incident electromagnetic wave. The geometric dimensions of the length, width and height of the unit can be set to 4mmx4mmx4mm, which is one fifth of the 15GHz vacuum wavelength, so as to ensure that the equivalent medium theory is established. Each unit can be composed of three mutually orthogonal medium rods, and the equivalent refractive index is controlled by adjusting the size of the medium rod. In the unit, the size of the medium rod in the y direction is half of the size of the medium rod in the x and z directions. Corresponding to Figure 3 As shown in the unit, the size of the medium rod in the x and z directions in the unit is a, and the size of the medium rod in the y direction is a / 2. By changing the structure of the medium rod in the unit, the unit has different responses to horizontal and vertical polarization, so as to realize the polarization conversion function of the whole Luneburg lens. The structure diagram of the Luneburg lens composed of a plurality of units is shown in Figure 4 and Figure 5 Specifically, Figure 4 is a structure diagram of a unit in the plane composed of x and y directions in the Luneburg lens, Figure 5This is a schematic diagram of the structure of a Luneburg lens composed of all its units. The Luneburg lens adopts a cross-shaped structure, and each internal unit is structurally connected to six adjacent units. Therefore, the Luneburg lens proposed in this embodiment of the invention is more structurally stable and does not require additional support structures.

[0070] By incident electromagnetic waves of different polarizations onto the element, parameter S is obtained. It can be understood that parameter S represents the scattering parameter, an important parameter in microwave transmission used to describe the frequency domain characteristics of the transmission channel. From parameter S, the equivalent refractive index n for x-polarized and y-polarized incident waves can be derived. x and n y For a graph showing the relationship between the equivalent refractive index of a unit cell and the normalized unit cell size ratio, please refer to [link / reference]. Figure 6 Where k represents the normalized element size ratio, k is the ratio of the size a of the dielectric rod in the element to the element size l, k = a / l. From Figure 6 As can be seen, by changing the unit cell within the achievable size range, the equivalent refractive index can be increased from 1 to... The change. For a graph showing the relationship between the equivalent refractive index and frequency of a unit cell in a Luneburg lens provided in this embodiment of the invention, please refer to... Figure 7 .from Figure 7 As can be seen, the unit has characteristics that are independent of frequency.

[0071] Understandably, two orthogonally linearly polarized waves of the same size but with a 90° phase difference can be synthesized into a circularly polarized wave. Therefore, using a linearly polarized antenna with a 45° polarization angle to the x-axis as a feed source, the 45° oblique linear polarization can be decomposed into mutually perpendicular x-polarization and y-polarization. When two polarized electromagnetic waves pass through a unit cell, they will produce different phase shifts because the unit cell has different equivalent refractive indices for different polarizations. and Phase shift and phase difference between Determined by the following formula:

[0072]

[0073] Where λ0 represents the free-space wavelength at 15 GHz, and l represents the size of the cell. When the total cell size is determined, it can be seen that the phase difference... This is determined by the equivalent refractive index difference of the unit. Therefore, by controlling the two polarized electromagnetic waves to have a 90° phase difference as they pass through the entire Luneburg lens, the conversion from linearly polarized to circularly polarized waves can be achieved. The total phase difference... It can be calculated using the following formula:

[0074]

[0075] Where N represents the number of units through which the incident electromagnetic wave passes. Let represent the equivalent refractive index of the i-th element through which the x-polarized incident electromagnetic wave passes. Let λ represent the equivalent refractive index of the i-th cell through which the y-polarized incident electromagnetic wave passes, l represent the geometric dimension of the cell height, and λ0 represent the free-space wavelength at 15 GHz.

[0076] Therefore, the number of layers M of the Luneburg lens is determined based on the first formula; the first formula is as follows:

[0077]

[0078] Where N represents the number of units through which the incident electromagnetic wave passes. Let represent the equivalent refractive index of the i-th element through which the x-polarized incident electromagnetic wave passes. Let λ represent the equivalent refractive index of the i-th cell through which the y-polarized incident electromagnetic wave passes, l represent the geometric size of the cell, and λ0 represent the free-space wavelength at 15 GHz.

[0079] Understandably, the equivalent refractive index of a single element is determined by the element itself. Once the geometric dimension *l* of the element is fixed, different equivalent refractive indices can be obtained by changing the dimensions of the dielectric rod within the element, thereby determining the value in the first formula. and In the first formula, l and λ0 are also fixed values. The only unknown in the first formula is N. By changing different numbers of layers M, different N values ​​can be obtained to make the first formula hold true, that is, the value on the left side of the equation is 90°. The corresponding value of M at this time is the optimal number of layers. The total phase difference of different layers can be calculated, as shown in Table 1, which is a table of total phase differences of different layers.

[0080] Table 1 Total Phase Difference of Different Layers

[0081] Number of layers 11 12 13 14 Total phase difference 83.5° 92.9° 100° 107.6°

[0082] To verify the calculation results, this embodiment of the invention established Luneburg lenses with different layer models and used a dipole antenna rotated 45° relative to the Luneburg lens as a feed source. For simulation diagrams of the axial ratios of the Luneburg lenses with different layer models provided in this embodiment of the invention, please refer to... Figure 8 . Figure 8 The simulated axial ratio values ​​are shown in the figure. It can be seen that the 13-layer Luneburg lens has a better 3dB axial ratio bandwidth in the Ku band. Therefore, the embodiment of this invention selects a 13-layer Luneburg lens for further research.

[0083] Feed antenna

[0084] In order to provide two linearly polarized waves, an embodiment of the present application designs a dual-polarized electromagnetic dipole antenna as a feed antenna.

[0085] The feed antenna is arranged at a polarization angle of 45° with respect to the x-axis of the Luneberg lens;

[0086] The feed antenna comprises a plurality of electromagnetic dipole antenna radiation structures, each of which introduces a first feed port and a second feed port arranged orthogonally.

[0087] The front view, top view and bottom view of the feed antenna provided by an embodiment of the present application are shown in Figure 9 , and the structural explosion diagram of the feed antenna is shown in Figure 10 . The structure of the feed antenna will be described below in combination with Figure 9 and Figure 10 .

[0088] Figure 9 The upper part of the figure shows the front view of the feed antenna, the middle part shows the top view of the feed antenna, and the lower part shows the bottom view of the feed antenna. The feed antenna provided by the embodiment of the present application adopts an electromagnetic dipole antenna radiation structure with a patch loaded with symmetrically etched gaps.

[0089] Specifically, the electromagnetic dipole antenna radiation structure, as shown in Figure 10 , can include:

[0090] a metal patch radiation layer 11, a first dielectric layer 12, four metal columns 13, a metal ground plate 14, a coupling gap 15, a second dielectric layer 16, a first feed port 18, a third dielectric layer 17 and a second feed port 19; wherein,

[0091] The metal patch radiation layer 11, the first dielectric layer 12, the metal ground plate 14, the second dielectric layer 16 and the third dielectric layer 17 are sequentially stacked from top to bottom;

[0092] The metal patch radiation layer 11 and the metal ground plate 14 are connected by four vertical metal through holes penetrating the first dielectric layer 12;

[0093] The four metal columns 13 are vertically arranged in the first dielectric layer 12, the first ends of the four metal columns 13 are connected with the metal patch radiation layer 11, and the second ends are connected with the metal ground plate 14;

[0094] The coupling gap 15 is arranged on the metal ground plate 14 by etching;

[0095] The first feed port 18 is arranged on the upper surface of the third dielectric layer 17;

[0096] The second feed port 19 is arranged on the lower surface of the third dielectric layer 17.

[0097] Understandable, from Figure 9 Top view and Figure 10 As can be seen, the metal patch radiating layer 11 may include four metal radiating patches, each employing a symmetrical slotted design. The four metal radiating patches realize an electric dipole. By employing the symmetrical slotted design shown in the figure on the four metal radiating patches, a radiating gap is created between the patches, and this radiating gap is used to realize a magnetic dipole, thus realizing an electromagnetic dipole. Each metal radiating patch has the same width and is a quarter wavelength, thereby forming two pairs of half-wave dipoles. Since the magnetic dipole is not composed of a conventional vertical short-circuited metal pillar with a wavelength height of a quarter wavelength, the height of the electromagnetic dipole antenna radiating structure is not limited to 0.25λ. c It can be as low as 0.16λ c , λ c This indicates the cutoff wavelength. In this embodiment of the invention, the electromagnetic dipole has four symmetrical gaps etched at the inner edges of the four metal radiating patches to extend the relative impedance bandwidth of the antenna.

[0098] The coupling gap 15 may include two orthogonally arranged I-shaped coupling gaps.

[0099] This invention employs a microstrip slot coupling feeding method to excite the radiating portion of the upper electromagnetic dipole. The metal ground plane 14 provided in this invention is etched with mutually orthogonal "I"-shaped coupling gaps, which, compared to rectangular gaps, can achieve greater energy coupling within a relatively small size.

[0100] A physical schematic diagram of the multi-beam Luneburg lens antenna provided in this embodiment of the invention is shown below. Figure 1 As shown, the five feed antennas are supported by a bracket, covering the Luneburg lens ±60°. The feed antennas rotate 45° relative to the Luneburg lens, generating two ±45° linearly polarized waves. This multi-beam Luneburg lens antenna has ten feed ports. Each electromagnetic dipole antenna radiation structure includes two feed ports: from the first feed port 3 of the second electromagnetic dipole antenna radiation structure to the second feed port 6 of the third electromagnetic dipole antenna radiation structure, and from the first feed port 7 of the fourth electromagnetic dipole antenna radiation structure to the second feed port 10 of the fifth electromagnetic dipole antenna radiation structure, exhibiting a symmetrical structure. For ease of analysis, the analysis below will focus on the first feed port 1 of the first electromagnetic dipole antenna radiation structure to the second feed port 6 of the third electromagnetic dipole antenna radiation structure.

[0101] Impedance characteristics were tested using a vector grid analyzer. Simulation and test results of the reflection coefficient of the fed antenna with and without a lens are shown in the attached graph. Figure 11 .from Figure 11As can be seen, the presence of the lens has no significant impact on the impedance matching of the feed antenna. Within a range less than -10dB, the relative bandwidth exceeds 33.7%, almost covering the entire Ku band.

[0102] A schematic diagram showing the reflection coefficients and isolation between different ports in a fed antenna, as shown below. Figure 12 As shown, from Figure 12 As can be seen, in the Ku band, the coupling between different ports of the feed antenna is less than -18.5dB.

[0103] Simulation results of the fed antenna and test results of axial ratio and gain in a microwave anechoic chamber are shown in the figure. Figure 13 As shown, axial ratio and gain were measured in a microwave anechoic chamber. Within the operating frequency range, the axial ratio was less than 3 dB. The gain of the fed antenna was approximately 7 dBi. After adding a Luneburg lens, the gain reached approximately 21 dBi. It can be seen that the Luneburg lens improved the gain of the fed antenna by 14 dB, demonstrating good radiation performance.

[0104] The test and simulation radiation patterns of the left-hand and right-hand circularly polarized 3D-printed multi-beam Luneburg lens antenna provided in this invention embodiment are available in the following reference: Figure 14 It can be seen that Figure 14 In the diagram, images (a), (b), and (c) represent the test and simulated radiation patterns for left-hand circular polarization, while images (d), (e), and (f) represent the test and simulated radiation patterns for right-hand circular polarization. The diagrams show five beams covering a spatial range of ±60°. It is understood that the wave obtained from the first feed port of all electromagnetic dipole antenna radiating structures is a left-hand circularly polarized wave (LHCP), and the wave obtained from the second feed port of all electromagnetic dipole antenna radiating structures is a right-hand circularly polarized wave (RHCP). Changing between left-hand and right-hand circular polarization modes only requires switching the feed port of the feed antenna, without any mechanical operation. Figure 14 As can be seen, the simulation results are in good agreement with the measurement results. This demonstrates that the Luneburg lens provided in this embodiment of the invention improves the gain of the fed antenna by 14dB, exhibiting excellent gain enhancement, and the gain consistency of each beam is good, with almost identical gains from different incident angles.

[0105] The feed antenna provided in this embodiment of the invention uses a dual-polarized electromagnetic dipole patch antenna as the feed source. The polarization mode of the final generated left-hand circular polarization or right-hand circular polarization can be easily changed simply by cutting off the feed port of the feed antenna instead of mechanically rotating it.

[0106] From the simulation and test results, the multi-beam dragon lens antenna provided by the embodiment of the application has different responses to the incident horizontal polarization and vertical polarization by adopting the asymmetric cross structure of the dragon lens, so that the dragon lens has the polarization conversion function, and realizes the conversion from double linear polarization to double circular polarization; the asymmetric structure is convenient for processing and manufacturing, and the finally formed dragon lens structure is stable, and the spherical structure avoids the disadvantages of large loss, high cost and dimension limitation caused by the traditional layered structure and flat plate structure. As the feed antenna, the feed antenna adopts a plurality of electromagnetic dipole antenna radiation structures, each electromagnetic dipole antenna radiation structure introduces a first feed port and a second feed port arranged orthogonally, and only by switching the corresponding feed port, the finally generated left-handed circular polarization or right-handed circular polarization polarization mode can be easily changed; on the basis of retaining the original high gain, wide band and low cost of the traditional dragon lens, the polarization conversion function is realized.

[0107] It should be noted that in the description of the present application, it should be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0108] The above only describes the preferred embodiments of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A dual circular polarized 3D printed multi-beam Luneberg lens antenna, using 3D printed metamaterial technology, characterized in that, Comprise: A dragon lens and a feed antenna; wherein, The dragon lens comprises M concentrically arranged spherical layers; wherein, M is a positive integer, each spherical layer has the same thickness and comprises a plurality of units with corresponding equivalent refractive indexes; the units are composed of dielectric rods orthogonal to each other in x, y and z directions; the sizes of the dielectric rods in x and z directions are the same, the size of the dielectric rod in y direction is smaller than that in x direction, and the equivalent refractive index of the corresponding unit is controlled by adjusting the size of the dielectric rod in the unit; for each unit in each spherical layer, the unit is structurally connected with the surrounding adjacent units; The feed antenna is arranged at a polarization angle of 45° relative to the x axis of the dragon lens; The feed antenna comprises a plurality of electromagnetic dipole antenna radiation structures, each electromagnetic dipole antenna radiation structure introduces a first feed port and a second feed port arranged orthogonally.

2. A dual circular polarized 3D printed multi-beam Luneberg lens antenna according to claim 1, wherein, The super material comprises a photosensitive resin.

3. A dual circular polarized 3D printed multi-beam Luneberg lens antenna according to claim 1, wherein, The refractive index of each spherical layer in the Luneburg lens gradually increases from 1 to 4. The dual circular polarized 3D printed multi-beam Luneberg lens antenna according to claim 1, wherein, M is 13.

5. The dual circular polarized 3D printed multi-beam Luneberg lens antenna according to claim 1, wherein, In the unit, the size of the dielectric rod in the y direction is half of the size of the dielectric rod in the x and z directions.

6. The dual circular polarized 3D printed multi-beam Luneberg lens antenna according to claim 1, wherein, The geometric dimensions of length, width and height of the unit are not greater than one fifth of the wavelength of the incident electromagnetic wave.

7. The dual circular polarized 3D printed multi-beam Luneberg lens antenna according to claim 1, wherein, The number of layers M of the dragon lens is determined based on a first formula; the first formula is as follows: where N denotes the number of cells through which the incident electromagnetic wave passes, ni(x) denotes the equivalent refractive index of the i-th cell through which an x-polarized incident electromagnetic wave passes, ni(y) denotes the equivalent refractive index of the i-th cell through which a y-polarized incident electromagnetic wave passes, I denotes the geometric dimension of the height of the cell, and λ0denotes the free-space wavelength at 15 GHz.

8. The dual circular polarized 3D printed multi-beam Luneberg lens antenna according to claim 1, wherein, The electromagnetic dipole antenna radiation structure comprises: A metal patch radiation layer (11), a first dielectric layer (12), four metal columns (13), a metal ground plate (14), a coupling gap (15), a second dielectric layer (16), a first feed port (18), a third dielectric layer (17) and a second feed port (19); wherein, The metal patch radiation layer (11), the first dielectric layer (12), the metal ground plate (14), the second dielectric layer (16) and the third dielectric layer (17) are sequentially stacked from top to bottom; The metal patch radiation layer (11) and the metal ground plate (14) are connected by four vertical metal through holes penetrating the first dielectric layer (12); The four metal columns (13) are vertically arranged in the first dielectric layer (12), the first ends of the four metal columns (13) are connected with the metal patch radiation layer (11), and the second ends are connected with the metal ground plate (14); The coupling gap (15) is arranged on the metal ground plate (14) by etching; The first feed port (18) is arranged on the upper surface of the third dielectric layer (17); The second feed port (19) is arranged on the lower surface of the third dielectric layer (17).

9. The dual circular polarized 3D printed multi-beam Luneberg lens antenna according to claim 8, wherein, The metal patch radiation layer (11) comprises: four metal radiation patches; wherein, each metal radiation patch adopts a symmetric slot design.

10. The dual circular polarized 3D printed multi-beam Luneberg lens antenna according to claim 8, wherein, The coupling gap (15) comprises two I-shaped coupling gaps arranged orthogonally.

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