A metamaterial luneberg lens and a preparation method thereof

Abstract

The application discloses a novel structure of a metamaterial dragonb ball lens and a preparation method thereof. The novel structure of the metamaterial dragonb ball lens comprises a dragonb ball lens and a patch antenna feed source. The patch antenna feed source is close to the surface of the dragonb ball lens antenna and is used for radiating electromagnetic signals to the dragonb ball lens. The dragonb ball lens is used for transmitting electromagnetic signals, so as to form a directional electromagnetic wave beam. The dragonb ball lens comprises a plurality of spherical shells, and each spherical shell is concentrically distributed and nested with each other. Each spherical shell comprises a plurality of unit structures, and the unit structure is composed of a cubic dielectric material and an air ball. The equivalent dielectric constant of a single spherical shell is changed by adjusting the proportion of the dielectric material and the air ball. The preparation method of the dragonb ball lens is a kind of structure change in the process of 3D printing of the spherical shell. The method is used for solving the problem that the support material cannot be removed when printing a device with a complex internal structure, so that the dielectric constant is closer to the ideal gradient change, and the performance is more stable.

Description

Technical Field

[0001] This invention belongs to the field of lens antenna technology, and specifically relates to a metamaterial Luneburg lens and its preparation method. Background Technology

[0002] A Luneburg lens is a spherical lens antenna, consisting of two parts: the Luneburg lens and a patch antenna feed. The feed is used to radiate electromagnetic signals to the Luneburg lens, and the Luneburg lens is used to transmit electromagnetic signals, thereby forming a directional electromagnetic beam.

[0003] Due to its advantages such as wide bandwidth, high gain, and multi-beam capability, Luneburg lenses have a wide range of applications, including communication systems, radar systems, aerospace applications, and scientific research. However, the attenuation of electromagnetic waves increases with frequency; the higher the frequency, the faster the attenuation. Therefore, high-gain antennas with wide scanning angles are urgently needed to achieve high coverage.

[0004] Luneburg lenses can focus spherical waves incident from any direction to a single point, and are also known as spherical wave lenses or focusing lenses. The focusing principle of Luneburg lenses is based on the distribution of wavefront phase and amplitude. When an electromagnetic wave is incident on a Luneburg lens, the shape and material of the lens alter the phase and amplitude distribution of the electromagnetic wave, thus focusing it to a single point. Because spherical Luneburg lenses possess perfect symmetry, placing feed sources at different positions on the lens surface can produce highly consistent beams. However, their non-conformal spherical structure limits their further development to some extent.

[0005] Traditional Luneburg lenses typically employ foaming technology and precision machining to achieve radial changes in dielectric constant. The foaming process generally involves creating a mixture of resin beads of varying sizes with different dielectric constants to represent the target dielectric material. A potential problem with this method is the existence of air gaps between layers, affecting the gradual change in refractive index. Furthermore, the foaming process easily creates through-holes, which reduces the lens's structural stability and impact resistance. For precision machining, lenses made of homogeneous materials such as glass or plastic are typically used. The manufacturing process mainly includes cutting, grinding, and polishing, requiring manual operation and experience. This means that human error is possible during manufacturing, and the production cycle is long, the processing is difficult, and the cost is high.

[0006] Currently, 3D printing technology cannot achieve unsupported printing of materials that are completely enclosed externally but have internal structures. Furthermore, the presence of support materials affects the dielectric constant, making it impossible to achieve the original effect.

[0007] Based on the above analysis, the problems and defects of the existing technology are as follows: When designing Luneburg lens antennas, there are no materials in nature with gradient changes in dielectric constant. In order to achieve radial changes in dielectric constant, traditional processing methods suffer from problems such as human error, long production cycle, high processing difficulty, and high processing cost. Moreover, due to its spherical shape, which is not convenient for conformal design, and its excessive size, its further development is limited. Summary of the Invention The purpose of this invention is to provide a metamaterial Luneburg lens and its fabrication method to solve the technical problems raised in the background art, so that the metamaterial Luneburg lens simultaneously possesses the characteristics of polarization insensitivity, high gain, wide scanning angle, and conformal feed source.

[0008] To achieve the above objectives, this invention provides a metamaterial Luneburg lens and its fabrication method, the technical solution of which is as follows: A first aspect of this application provides a metamaterial Luneburg lens, comprising a Luneburg lens and a patch antenna feed, the patch antenna feed being close to the surface of the lens. The Luneburg lens comprises multiple concentrically arranged spherical shells; The patch antenna feed has a flexible feature, which allows it to conform to a spherical lens; The radiation direction of the patch antenna feed is aligned with the central axis of the Luneburg lens; The spherical shell has several uniformly distributed unit structures, each consisting of a cubic dielectric material and an air sphere. The effective dielectric constant of the spherical shell can be changed by adjusting the ratio of the dielectric material to the air sphere.

[0009] Furthermore, the Luneburg lens contains several unit structures.

[0010] Furthermore, the number and size of the unit structures are inversely proportional to the equivalent dielectric constant of the spherical shell.

[0011] Furthermore, the refractive index of the Luneburg lens satisfies:

[0012] in, n This indicates the refractive index of the Luneburg lens. r Indicates the distance from the center of the lens. R This indicates the radius of the Luneburg lens.

[0013] Furthermore, under ideal conditions, the equivalent dielectric constant of the innermost spherical shell of the Luneburg lens is at most 2, and the equivalent dielectric constant of the spherical shell can be radially and regularly reduced by adjusting the size of the air sphere until the equivalent dielectric constant is reduced to 1.

[0014] Furthermore, the material used to fabricate the Luneburg lens has a dielectric constant. It is a 3300PA material with a strength of 2.45.

[0015] Furthermore, the side length of the unit structure does not exceed 1 / 4 wavelength of the center frequency.

[0016] Furthermore, the radius R of the Luneburg lens, which is composed of multiple spherical shells, is 12 cm.

[0017] Furthermore, the patch antenna feed is selected to operate in the 2~10 GHz frequency band and moves along the surface of the Luneburg lens to achieve multi-beam scanning.

[0018] A second aspect of this application provides a method for fabricating a metamaterial Luneburg lens as described above, the method comprising: Optimize the layered design and determine the number of spherical shells; The equivalent dielectric constant of each spherical shell is estimated using the following formula:

[0019] in The dielectric constant of the inserted material is given. The dielectric constant of the substrate material is given. This is the equivalent dielectric constant value. The proportion of air spheres to the cubic medium material; Based on the number of spherical shell unit structures and the size of the air sphere, 12 concentrically arranged spherical shells were designed. Because the air sphere portion in the unit structure requires support from unsintered powder, and the internal structure of the lens is quite complex, integral printing would make it difficult to completely remove the supporting powder. Therefore, it is proposed to divide the 12 concentrically arranged spherical shells into 24 hemispherical shells for 3D printing. During the printing process, a structural transformation method is proposed to divide each spherical shell into equal parts. A, B Two parts, then the first i A spherical shell A Part and the i+1 A spherical shell B Partially made into a new spherical shell N_i This exposes the enclosed space of the original unit structure, making the supporting material visible on the outer surface and easy to remove. After printing, the upper and lower hemispherical shells are positioned and assembled into a Luneburg lens using glue.

[0020] Compared with existing technologies, the above technical solution has at least the following beneficial effects: 1) This invention can meet the high gain requirement to the greatest extent, with an extremely wide operating bandwidth, achieving high coverage. The flexible feed solves the problem that spherical antennas are not easy to conform to.

[0021] 2) The internal unit structure of the present invention has omnidirectional uniformity of air spheres, thus achieving insensitivity to polarization.

[0022] 3) This invention adopts a layered spherical shell printing assembly method and proposes a structural transformation method during the printing process, which solves the problem that the support material cannot be removed when printing devices with complex internal structures. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0024] Figure 1 This is an overall view of the Luneburg lens antenna provided in an embodiment of the present invention; Figure 2 This is a front view of the Luneburg lens antenna provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the Luneburg lens unit structure provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the spherical shell structure of the Luneburg lens provided in an embodiment of the present invention; Figure 5 A diagram showing the relationship between the size of the air sphere and the equivalent dielectric constant in the unit structure provided as an example of the present invention; Figure 6 This is a schematic diagram of the manufacturing process of the Luneburg lens antenna provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of structural transformation during the printing process provided in an embodiment of the present invention; Figure 8 This is a perspective view of the patch antenna feed structure provided in an embodiment of the present invention; Figure 9 This is the normalized gain diagram of the present invention at a frequency of 2 GHz; Figure 10 This is the normalized gain diagram of the present invention at a frequency of 6 GHz; Figure 11 This is the normalized gain diagram of the present invention at a frequency of 10 GHz; Figure 12 The support frame for the Luneburg lens provided in the embodiment of the present invention; Figure label: 1-Lunnberg lens, 11-Lunnberg lens unit structure, 12-Spherical shell, 2-Patch antenna feed, 21-Patch antenna dielectric layer, 22-Radiating patch. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0026] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0027] Figure 1 This is a three-dimensional schematic diagram of the Luneburg lens antenna provided in this embodiment; Figure 2 This is a schematic structural view of the Luneburg lens antenna provided in this embodiment. This embodiment of the invention provides a metamaterial Luneburg lens, such as... Figure 1 and Figure 2 As shown, the metamaterial Luneburg lens includes a Luneburg lens 1 and a patch antenna feed 2; the patch antenna feed 2 is close to the surface of the Luneburg lens antenna and is used to radiate electromagnetic signals to the Luneburg lens 1, and the Luneburg lens 1 is used to transmit electromagnetic signals, thereby forming a directional electromagnetic beam.

[0028] For example, the Luneburg lens material is 3300PA, the radius of the Luneburg lens 1 is 12 cm, and the material of the flexible patch antenna feed structure medium (patch antenna feed 2) is F4B.

[0029] In some embodiments, the unit structures within the Luneburg lens 1 are regularly arrayed in each spherical shell 12.

[0030] Figure 3 This is a schematic diagram of the unit structure of the Luneburg lens antenna provided in this embodiment. This structure, when arranged in an array, will yield... Figure 4 Multiple concentrically arranged hemispherical shells Figure 4 This is a schematic diagram of the structure of the hemispherical shell of the Luneburg lens antenna provided in this embodiment. Each shell is defined as 12.1, 12.2, 12.3, ..., 12.12 from the inside out, for a total of 12.

[0031] Shells 12.1 to 12.12 have the same thickness, and the thickness of each spherical shell is no greater than 1 / 4 wavelength, which is taken in this example but is not limited to 10 mm.

[0032] Layers 12.1 to 12.12 of the same type have the same unit structure air sphere size, while different layers have different unit structure air sphere sizes and the number of unit structures. The equivalent dielectric constant of the sphere is related to the air sphere size.

[0033] The radii of the spherical shells increase sequentially from 12.1 to 12.12. The relationship between the size of the air sphere and the equivalent dielectric constant of each spherical shell unit structure is shown in the figure below. Figure 5 As shown.

[0034] Furthermore, embodiments of the present invention also provide a method for fabricating a metamaterial Luneburg lens, such as... Figure 6 The process diagram shows that the preparation method includes the following steps: Step S1: Optimize the layered design and determine the ideal number of spherical shells; Step S2, according to the A-BG formula: (in The dielectric constant of the inserted material is given. The dielectric constant of the substrate material is given. Let p be the equivalent dielectric constant, where p is the proportion of the air sphere to the cubic dielectric material. Estimate the equivalent dielectric constant of the spherical shell.

[0035] Step S3: Based on the calculation results of S2, design a spherical shell with 12 concentric layers; Step S4: Generate an STL file in suitable software and print each spherical shell using 3D printing technology.

[0036] Step S5: Since current domestic 3D printing technology cannot achieve unsupported material printing with a fully enclosed exterior and internal structure, and the presence of support material affects the dielectric constant, the original effect cannot be achieved. In order to solve this problem, the 12 concentrically arranged spherical shells designed in step S3 are divided into 24 hemispherical shells and printed through a structural transformation method, so that the support material is exposed on the outer surface and can flow out naturally. After printing, glue is used to dot-apply and assemble it into Luneburg lens 1.

[0037] Specifically, in step S5, the assembly method can be achieved by applying strong adhesive to the contact surfaces of the concentrically arranged spherical shells and then assembling them into a whole by die casting, or by using bolts or other connection methods to connect and assemble the thin layers together. However, the presence of different dielectric materials will more or less affect their equivalent dielectric constant. Finally, the method of applying glue in dots is used to avoid or reduce the impact on the dielectric constant and ensure the lens performance.

[0038] Figure 7 This is a schematic diagram of the structural transformation during the printing process provided in this embodiment, in which each spherical shell is divided into equal parts. A, B Two parts, then the first i A spherical shell A Part and the i+1 A spherical shell B Partially made into a new spherical shell N_i This reveals the enclosed space of the original unit structure.

[0039] Figure 8 This is a three-dimensional view of the flexible patch antenna structure provided in this embodiment. This example uses, but is not limited to, a patch antenna as the feed source. The dielectric material of the flexible patch antenna feed structure is F4B with a dielectric thickness of 1.27 mm. The size of the radiating patch is 9.15 mm × 9.15 mm. To ensure conformal compatibility with the spherical Luneburg lens, an extremely low dielectric thickness is used to achieve high curvature bending.

[0040] Simulation experiments were conducted on a metamaterial Luneburg lens provided in an embodiment of the present invention, and the following results were obtained: Figure 9 , Figure 10 , Figure 11 The figure shows the gain radiation patterns of the present invention at frequencies of 2 GHz, 6 GHz, and 10 GHz. As can be seen from the figure, the Luneburg lens antenna provided by the present invention has good directional radiation characteristics, high gain, and good coverage at frequencies of 2 to 10 GHz.

[0041] Figure 12 The support frame for the Luneburg lens provided in the embodiment of the present invention is used to place the Luneburg lens and the patch antenna feed during actual testing.

[0042] The Luneburg lens antenna with wide horizontal beam coverage provided in this embodiment satisfies the performance requirements of high gain and high directivity to the greatest extent, while achieving insensitivity to polarization and having a wide operating bandwidth.

[0043] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A metamaterial Luneburg lens, characterized in that, The device includes a Luneburg lens (1) and a patch antenna feed (2), wherein the patch antenna feed (2) is in close contact with the surface of the Luneburg lens (1), characterized in that: The Luneburg lens (1) comprises a plurality of concentrically arranged spherical shells; The patch antenna feed (2) has a flexible feature to achieve conformal integration with the spherical lens; The radiation direction of the patch antenna feed (2) is aligned with the central axis of the Luneburg lens (1); Several unit structures are uniformly distributed on the spherical shell. Each unit structure is composed of cubic dielectric material and air spheres. The effective dielectric constant of the spherical shell is obtained by adjusting the ratio of dielectric material to air spheres. The metamaterial Luneburg lens is prepared by the following method: Optimize the layered design and determine the number of spherical shells; The equivalent dielectric constant of each spherical shell can be estimated using the following formula: in The dielectric constant of the inserted material is given. The dielectric constant of the substrate material is given. This is the equivalent dielectric constant value. The proportion of air spheres to the cubic medium material; Based on the number of spherical shell unit structures and the size of the air sphere, 12 concentrically arranged spherical shells were designed. The 12 concentrically arranged spherical shells were divided into 24 hemispherical shells for 3D printing. During the printing process, each spherical shell was divided into equal parts. A, B Two parts, then the first i A spherical shell A Part and the i+1 A spherical shell B Partially made into a new spherical shell N_ i This exposes the enclosed space of the original unit structure, allowing the supporting material to be exposed on the outer surface, making it easier to remove. After printing, position the upper and lower hemispherical shells and assemble them into a Luneburg lens by applying glue.

2. The metamaterial Luneburg lens according to claim 1, characterized in that, The Luneburg lens (1) contains several unit structures.

3. The metamaterial Luneburg lens according to claim 2, characterized in that, The number and size of the unit structures are inversely proportional to the equivalent dielectric constant of the spherical shell.

4. The metamaterial Luneburg lens according to claim 1, characterized in that, The refractive index of the Luneburg lens (1) satisfies: in, n This indicates the refractive index of the Luneburg lens. r Indicates the distance from the center of the lens. R This indicates the radius of the Luneburg lens.

5. The metamaterial Luneburg lens according to claim 1, characterized in that, The equivalent dielectric constant of the innermost spherical shell of the Luneburg lens (1) is 2, and the equivalent dielectric constant of the spherical shell is radially reduced by adjusting the size of the air sphere until the equivalent dielectric constant is reduced to 1.

6. The metamaterial Luneburg lens according to claim 1, characterized in that, The material used to fabricate the Luneburg lens (1) is a dielectric constant. It is a 3300PA material with a strength of 2.

45.

7. The metamaterial Luneburg lens according to claim 1, characterized in that, The side length of the unit structure does not exceed 1 / 4 wavelength of the center frequency.

8. The metamaterial Luneburg lens according to claim 1, characterized in that, The radius R of the Luneburg lens, which is composed of multiple spherical shells, is 120 cm.

9. The metamaterial Luneburg lens according to claim 1, characterized in that, The patch antenna feed (2) is selected to operate in the 2~10 GHz frequency band and moves along the surface of the Luneburg lens (1) to achieve multi-beam scanning.

Images