Dielectric lens and dielectric lens antenna

Abstract

The invention discloses a dielectric lens and a dielectric lens antenna. The dielectric lens comprises B lens units, the B lens units are distributed in an array to form a lens array which is square on the whole, the middle part of the lens array is circular, the lens units distributed at the edge position of the array are higher than the lens units distributed at the circular position in the middle of the array, and the middle position of the lens unit array forms a circular concave cavity. The whole lens unit is a cuboid and comprises two impedance matching layers and a square dielectric cylinder, and the two square end faces of the square dielectric cylinder are connected with the impedance matching layers respectively. And four cube-shaped through holes are symmetrically formed in the middle of the impedance matching layer. The dielectric lens antenna comprises the dielectric lens and a feed source antenna, and the feed source antenna is arranged on one side of the dielectric lens and located at the position of an extension line of the geometric center of the dielectric lens. The dielectric lens provided by the invention has relatively high transmissivity, and the dielectric lens antenna has more excellent gain performance, broadband coverage and relatively low production cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and particularly relates to a dielectric lens and a dielectric lens antenna. Background Art

[0002] In the upcoming fifth-generation communication system (5G), countries and regions have proposed a series of utilization schemes for millimeter-wave frequency bands, including the application of the Ka band. Compared with microwaves, the millimeter-wave frequency band has a shorter wavelength, enabling it to have higher resolution in fields such as radar and imaging. With the rapid development of civil technologies such as 5G communication, wireless virtual reality, autonomous driving, and security inspection, millimeter-wave technology will be widely used in daily life. As an important electromagnetic wave receiving and transmitting component in wireless communication devices, the performance of the antenna is crucial for wireless communication systems, and among them, gain is a key indicator for measuring antenna performance. High-gain antennas are widely used in wireless communication systems such as radar and satellite communication. Therefore, improving antenna gain has always been the focus of research.

[0003] Traditional high-gain antennas are usually designed based on optical ray theory and array theory. Common types include array antennas, reflector antennas, and lens antennas. Array antennas have a lower profile, but their feeding network is complex and has large losses. The working principle of reflector antennas and lens antennas is to convert the electromagnetic waves emitted by the feed source through a reflecting array or a lens, so that the spherical wave is converted into a plane wave, thereby improving the antenna gain. Although reflector antennas can achieve high gain, they have disadvantages such as large volume and heavy weight, and there may also be problems of feed source occlusion compared with lens antennas. Traditional lens antennas adjust the propagation path of electromagnetic waves by changing the shape and material of the lens, so as to convert the spherical wave into a plane wave, such as delay lenses, acceleration lenses, Luneburg lenses, and Maxwell fish-eye lenses. However, traditional lens antennas have problems such as low efficiency and large volume. How to overcome these disadvantages while achieving high gain has become a current research difficulty.

[0004] Currently, many millimeter-wave systems still use traditional devices such as dielectric lenses and parabolic antennas. These devices adopt a spatial feeding structure without a feeding network, thus avoiding related losses and effectively achieving high gain and focusing functions. However, due to their generally large size, heavy weight, and complex structure, they are not conducive to installation. Especially in the context of the increasing requirements for integration and cost control, their applications are somewhat restricted. In contrast, the lens antenna based on the periodic structure not only has the advantages of no feeding network, high gain, and focusing, but also has the characteristics of flexible design, small size, easy processing, and low cost, especially suitable for the millimeter-wave band. The lens antenna usually adopts a metal structure, and the required transmission phase is achieved by adjusting the unit size. However, the feeding loss, conductor loss, and manufacturing accuracy limitations restrict the application of metal superlenses in the millimeter-wave and terahertz bands, especially in the field of high-gain antennas. Compared with metal superlenses, dielectric superlenses are more suitable for the millimeter-wave band due to their material properties and can better meet the application requirements of this band.

[0005] The journal literature "Design of Millimeter-Wave Broadband High-Gain Dielectric Superlens Antenna" (Journal Name: Telecommunication Engineering, 2022, 62(4)) discloses a fully dielectric superlens designed based on the phase compensation principle, and a horn antenna is used as the feed source to feed the lens. By changing the height of the dielectric unit and the depth of the dielectric hole, a sufficient phase compensation range is achieved. The lens has a total of 506 units, the aperture size is 44.6mm×46.6mm, and the focal diameter ratio of this transmission array antenna is 1. The overall structure of the lens is as shown in Appendix Figure 1 shown, and its unit structure is as shown in Appendix Figure 2 shown. The unit is composed of a fully dielectric material, and the unit structure consists of a cubic column and a square hole, with side length a = 2mm and hole length b = 1.4mm. Different phases are achieved by changing the height of the cubic column and the depth of the square hole. Among them, the square hole plays a role in reducing reflection while adjusting the phase. Appendix Figure 3 and Appendix Figure 4 respectively show the transmission phase and transmission amplitude of different lens units of this dielectric superlens antenna.

[0006] Existing superlens antennas mainly regulate the electromagnetic wavefront by precisely designing the unit structure, but still face several key problems. First of all, simultaneously achieving broadband and high gain is a challenge that is difficult to overcome for current superlenses. Although traditional lens antennas can effectively improve the gain, they often have disadvantages such as low efficiency and large volume. Especially in the millimeter-wave band, these problems are more prominent. In addition, the millimeter-wave has extremely high requirements for the processing accuracy of antennas, making the design of high-gain antennas more complex and costly. Summary of the Invention

[0007] To solve the problems of the existing technology, the present invention discloses a dielectric lens and a dielectric lens antenna.

[0008] In a first aspect, the present invention proposes a dielectric lens. The dielectric lens includes B lens units, and the B lens units are arranged in an array according to a preset rule to form a lens array with an overall square shape. The middle part of the lens array is circular, and the lens units distributed at the edge positions of the array are higher than the lens units distributed at the circular position in the middle of the array, forming a circular concave cavity at the middle position of the lens unit array.

[0009] Further, the lens unit is integrally in the shape of a cuboid and includes two layers of impedance matching layers and a square dielectric column. The two square end faces of the square dielectric column are respectively connected to the impedance matching layers; 4 through holes in the shape of cubes are symmetrically arranged in the middle of the impedance matching layers.

[0010] In a second aspect, the present invention proposes a dielectric lens antenna. The dielectric lens antenna includes the dielectric lens proposed in the first aspect of the present invention and a feed antenna. The feed antenna is arranged on one side of the dielectric lens and is located on the extension line of the geometric center of the dielectric lens.

[0011] Advantages of the present invention:

[0012] 1. The lens unit designed by the present invention has 8 through holes and a square dielectric column with an adjustable height h, which can achieve phase compensation and impedance matching, can achieve a complete 2π phase coverage, and optimizes the radiation efficiency of the lens unit. This lens unit structure not only effectively improves the transmittance but also significantly reduces the reflectance, ensuring the high performance and stability of the dielectric lens and the dielectric lens antenna.

[0013] 2. The dielectric lens antenna designed by the present invention has better gain performance. During simulation verification, in the frequency band from 26 GHz to 40 GHz, the 1 dB gain bandwidth of the dielectric lens antenna of the present invention reaches 13.2%, and the highest aperture efficiency is 55.2%. Especially at 40 GHz, the antenna gain reaches 29.57 dBi. These performances make the present invention have a wide application prospect in millimeter-wave and terahertz communications.

[0014] 3. The lens unit of the present invention is manufactured by a 3D printing method. The 3D printed lens antenna structure is light, has a low material cost (using an economical 3D printing material), and can be processed with high precision by a 3D printing device, greatly reducing the processing difficulty and cost. This makes the lens antenna very suitable for mass production and practical applications, especially suitable for communication systems with strict requirements on cost and size. Description of the Drawings

[0015] Figure 1 It is a schematic diagram of the overall structure of an existing dielectric lens antenna;

[0016] Figure 2 Schematic diagram of the lens unit structure of the existing dielectric lens antenna;

[0017] Figure 3 Schematic diagram of the transmission amplitude of different lens units of the existing dielectric lens antenna;

[0018] Figure 4 Schematic diagram of the transmission phase of different lens units of the existing dielectric lens antenna;

[0019] Figure 5 Schematic diagram of the overall structure of the embodiment of the present invention;

[0020] Figure 6 Schematic diagram of the three-dimensional structure of the back surface of the dielectric lens in the embodiment of the present invention;

[0021] Figure 7 Schematic diagram of the structure of the lens unit in the embodiment of the present invention;

[0022] Figure 8 Phase and amplitude response curves of the lens unit in the embodiment of the present invention during simulation verification;

[0023] Figure 9 Phase distribution diagram of the array surface of the dielectric lens in the embodiment of the present invention obtained by simulation calculation;

[0024] Figure 10 Height distribution diagram of each lens unit in the dielectric lens of the embodiment of the present invention obtained by simulation calculation;

[0025] Figure 11 Phase error distribution diagram of the array surface of the dielectric lens in the embodiment of the present invention obtained by simulation calculation;

[0026] Figure 12 Physical photo of the dielectric lens in the embodiment of the present invention;

[0027] Figure 13 Radiation pattern of the dielectric lens antenna in the embodiment of the present invention at 33 GHz during simulation verification;

[0028] Figure 14 Gain diagram of the feed source and the lens antenna during simulation verification;

[0029] In the drawings, 1 represents the dielectric lens; 2 represents the feed antenna;

[0030] 3 represents the square dielectric column; 4 represents the impedance matching layer. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] Figure 5 It is a schematic diagram of the overall structure of the embodiment of the present invention. Figure 5 Among them, 1 represents a dielectric lens, and 2 represents a feed antenna.

[0033] Figure 6 It is a schematic diagram of the three-dimensional structure of the back of the dielectric lens in the embodiment of the present invention.

[0034] The embodiment of the present invention proposes a dielectric lens. Referring to Figure 5 、 6 As shown, the dielectric lens includes B lens units. The B lens units are arranged in an array according to a preset rule to form a lens array with an overall square shape. The middle part of the lens array is circular. The lens units distributed at the edge positions of the array are higher than the lens units distributed at the circular position in the middle of the array, and a circular concave cavity is formed at the middle position of the lens unit array.

[0035] For example, the lens array composed of B lens units includes 20×20 lens units (both the length and width are 20 lens units), that is, B = 20×20.

[0036] Figure 7 It is a schematic diagram of the structure of the lens unit in the embodiment of the present invention. Figure 7 Among them, 3 represents a square dielectric column, 4 represents an impedance matching layer, p represents the side length of the square dielectric column, t represents the height of the cubic through hole, w represents the side length of the square in the cubic through hole, and h represents the height of the square dielectric column.

[0037] In the shown embodiment, referring to Figure 7 As shown, the lens unit is integrally in the shape of a cuboid and includes two layers of impedance matching layers 4 and a square dielectric column 3. The two square end faces of the square dielectric column 3 are respectively connected to the impedance matching layer 4; four cubic through holes are symmetrically arranged in the middle of the impedance matching layer 4. By arranging through holes in the two layers of impedance matching layers 4, the impedance matching of the contact surface between the dielectric and the air can be strengthened. Observed from a top view, the impedance matching layer 4 as a whole presents a "field" shape. Designing the structure of the lens unit in this way can effectively reduce reflection and improve the transmittance of the lens unit.

[0038] In the illustrated embodiment, the size of the lens unit is approximately half a wavelength of the center frequency. Specifically, the length and width of the lens unit are 4.9 mm, that is, 4.9 mm × 4.9 mm, and the height of the lens unit is variable and adjusted according to actual needs.

[0039] Figure 8 For the phase and amplitude response curves of the lens unit in the embodiment of the present invention during simulation verification. Figure 8 Among them, S21(dB) represents the insertion loss of the lens unit, the ordinate represents the transmission phase of the lens unit, the black diagonal line represents the phase response curve of the lens unit during simulation verification, and the red curve represents the amplitude response curve of the lens unit.

[0040] In the illustrated embodiment, the height of the square dielectric column 3 is adjusted according to needs. By adjusting the height h of the square dielectric column, the parameters of the lens unit can be adjusted, and a complete 2π phase coverage can be achieved, that is, a phase of 0 - 360° can be achieved. Refer to Figure 8 As shown, when h increases from 4 mm to 13 mm, the unit can achieve a complete 2π phase coverage, and the transmission amplitude is greater than -0.5 dB.

[0041] The phase distribution on the lens array is determined by the distance between the feed at the focal point and each lens unit.

[0042] In the illustrated embodiment, the transmission phase Φ(x m , y n ) of the lens unit is calculated by the formula:

[0043]

[0044] Among them, Φ(x m , y n ) represents the phase shift amount required to be achieved by the lens unit in the lens array, (x m , y n ) represents the coordinates of the lens unit, x m represents the coordinate of the lens unit on the x-axis, y n represents the coordinate of the lens unit on the y-axis, k0 is the free space wave number in vacuum, R i represents the distance from the phase center of the feed to the i-th lens unit, represents the main beam direction, where θ represents the elevation angle of the beam, represents the azimuth angle of the beam.

[0045] The lens unit in the embodiment of the present invention has 8 through holes and a square dielectric column with an adjustable height h, which can achieve phase compensation and impedance matching, and optimize the radiation efficiency of the lens unit. This lens unit structure not only effectively improves the transmittance but also significantly reduces the reflectance, ensuring the high performance and stability of the dielectric lens and the dielectric lens antenna.

[0046] In the illustrated embodiment, the dielectric lens is fabricated by a 3D printing method. The dielectric constant of the dielectric lens is 4.4, and the tangent of the loss angle is 0.004. The material with a high dielectric constant greatly reduces the profile of the dielectric lens array.

[0047] When fabricating the dielectric lens by a 3D printing method, the printed dielectric lens has a light structure and low material cost; high-precision machining is performed by a 3D printing device, greatly reducing the machining difficulty and cost and improving the production efficiency of the dielectric lens. This makes the antenna very suitable for mass production and practical applications, especially for communication systems with strict requirements on cost and size.

[0048] Based on the same inventive concept, an embodiment of the present invention provides a dielectric lens antenna that employs the above dielectric lens. The dielectric lens antenna has the same or similar technical features as the above dielectric lens. For the same or similar technical features, they will not be described in detail hereinafter.

[0049] Refer to Figure 5 As shown, the dielectric lens antenna includes the dielectric lens 1 and the feed antenna 2. The feed antenna 2 is disposed on one side of the dielectric lens 1 and is located on the extension line of the geometric center of the dielectric lens 1.

[0050] Refer to Figure 5 As shown, specifically, the feed antenna 2 is disposed on the back side of the front surface of the dielectric lens 1 and is located on the extension line of the geometric center of the dielectric lens 1.

[0051] In the illustrated embodiment, the dielectric feed antenna 2 is a standard gain horn antenna in the Ka band. The radiation pattern of the feed should have good axial symmetry performance, with the side lobes and back lobes as small as possible, the main lobe having a small edge illumination level for the array, and the radiation level outside the illumination angle being small; secondly, within the illumination angle range, the feed should have a clear phase center with small phase fluctuations to ensure an accurate phase distribution for the air-fed array antenna; as a feed, its reflection coefficient bandwidth should be greater than the operating bandwidth of the air-fed array element, and within the operating frequency band, the beam width should remain stable. The horn antenna is one of the most commonly used feeds for dielectric lens antennas. An embodiment of the present invention can select a standard gain horn antenna in the Ka band as the feed, with its operating frequency ranging from 26 GHz to 40 GHz.

[0052] In the illustrated embodiment, the focal length of the dielectric lens antenna is 78.4 mm, and the focal diameter ratio of the dielectric lens antenna is 0.8.

[0053] The dielectric lens antenna designed in the present invention achieves high gain and high aperture efficiency. During simulation verification, the 1dB gain bandwidth of the dielectric lens antenna in the frequency band from 26GHz to 40GHz is 13.2%, and the highest aperture efficiency is 55.2%. Especially at 40GHz, the antenna gain reaches 29.57dBi. These performances enable the present invention to have broad application prospects in millimeter-wave and terahertz communications.

[0054] Simulation verification and experimental verification:

[0055] Figure 9 To obtain the array surface phase distribution diagram of the dielectric lens in the embodiment of the present invention through simulation calculation. Figure 9 In it, the abscissa represents the x coordinate of the lens array surface, the ordinate represents the y coordinate of the lens array surface, and the numbers 0 - 350 represent the realized transmission phase.

[0056] Refer to Figure 9 As shown, according to the transmission phase Φ(x m , y n ) calculation formula, the phase distribution diagram required for the position of each lens unit is calculated. Then, the height of the lens unit is adjusted to the corresponding height, and the lens unit is placed at the corresponding position. In this way, B lens units are arranged in an array according to a preset rule, forming a transmission array as a whole. After 3D printing, a dielectric lens is obtained.

[0057] Figure 10 To obtain the height distribution diagram of each lens unit in the dielectric lens in the embodiment of the present invention through simulation calculation. Figure 10 In it, the abscissa represents the x coordinate of the lens array surface, the ordinate represents the y coordinate of the lens array surface, and the numbers 5 - 13 represent the height distribution of the lens units.

[0058] Combined with the phase distribution curve of the lens units, the lens units are arranged in sequence according to the calculated height distribution diagram, refer to Figure 10 As shown. In an ideal situation, each lens unit should be optimized to achieve a continuously varying phase shift value in the range of 0° to 360° to achieve the best radiation performance. However, in practice, this is almost impossible.

[0059] Figure 11 To obtain the array surface phase error distribution diagram of the dielectric lens in the embodiment of the present invention through simulation calculation. Figure 11 In it, the abscissa represents the x coordinate of the lens array surface, the ordinate represents the y coordinate of the lens array surface, and the numbers -1.5 - 1.5 represent the error value between the phase of the actual unit at this position and the phase calculated for this position.

[0060] Refer to Figure 9 、 11As shown, the dielectric lens of the embodiment of the present invention can well cover the phase of 0 - 360°, and the phase error is between ±2°.

[0061] Figure 12 This is a physical photo of the dielectric lens of the embodiment of the present invention. Figure 12 In, the physical object of the dielectric lens is made by the 3D printing method, and its specific printing method is FDM. The dielectric constant of the dielectric lens is 4.4, and the loss tangent is 0.004.

[0062] It should be noted that Fused Deposition Modeling (FDM) is a widely used 3D printing technology. The FDM 3D printer builds objects layer by layer by heating and extruding thermoplastic materials (usually PLA, ABS or other composite materials). The printing process starts from the bottom and builds layer by layer upwards, and each layer is tightly combined with the previous layer. This technology can create objects with complex geometries, including internal cavities and overhanging structures.

[0063] Figure 13 This is the radiation pattern of the dielectric lens antenna of the embodiment of the present invention at 33 GHz during simulation verification. Figure 13 In, Theta represents the elevation angle of the dielectric lens antenna pattern, the E-plane represents the plane of the electric field direction and the maximum radiation direction, which is the xoz plane here. The H-plane represents the plane of the magnetic field direction and the maximum radiation direction, which is the yoz plane here. From Figure 13 it can be seen that the patterns of the E-plane and H-plane of the dielectric lens antenna in the embodiment of the present invention during simulation verification are nearly symmetric.

[0064] Figure 14 This is the gain diagram of the feed and the lens antenna during simulation verification. From Figure 14 it can be seen that during simulation verification, the gain trends of the feed and the lens antenna are generally consistent.

[0065] From Figure 13 、 14 it can be seen that during simulation verification, the gain of the feed antenna is 14.51 - 18.39 dBi in the frequency band of 26 - 40 GHz, the patterns of the E-plane and H-plane of the feed are nearly symmetric, the -10 dBi beam width is 28°, and the gain is greater than 25.5 dBi in the frequency band of 26 - 40 GHz after loading the dielectric lens. At 31 GHz, the lens improves by 12.44 dBi compared with the feed, and in the whole frequency band, the minimum improvement is 11 dB, and the 1 dB gain bandwidth is 13.2% (31.65 GHz - 40 GHz). Thus, the dielectric lens and the dielectric lens antenna proposed by the present invention have more excellent gain performance and bandwidth.

[0066] The embodiments of the present invention have more excellent gain performance, broadband coverage and lower production costs. The antenna design of the present invention can not only be widely applied to fields such as 5G communication, millimeter-wave radar, and satellite communication, but also play an important role in future wireless communication, Internet of Things and terahertz technology.

[0067] Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. The storage medium may include: ROM, RAM, disk or optical disc, etc.

[0068] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dielectric lens, characterized in that, It includes B lens units, and the B lens units are arranged in an array according to a preset rule to form a lens array with a square overall shape. The middle part of the lens array is circular. The lens units distributed at the edge positions of the array are higher than the lens units distributed at the middle circular position of the array, and a circular concave cavity is formed at the middle position of the lens unit array.

2. The dielectric lens according to claim 1, wherein The lens unit is in the overall shape of a cuboid and includes two impedance matching layers (4) and a square dielectric column (3). The two square end faces of the square dielectric column (3) are respectively connected to the impedance matching layers (4); 4 through holes in the shape of cubes are symmetrically arranged in the middle of the impedance matching layer (4).

3. The dielectric lens according to claim 1, wherein The size of the lens unit is 4.9 mm × 4.9 mm.

4. The dielectric lens according to claim 2, wherein The height of the square dielectric column (3) is adjustable, and the height range is 4 mm - 13 mm.

5. The dielectric lens according to claim 1, characterized in that, The transmission phase Φ(x m , y n ) of the lens unit is calculated by the following formula: Among them, Φ(x m , y n ) represents the phase shift amount required to be achieved by the lens unit in the lens array, (x m , y n ) represents the coordinates of the lens unit, x m represents the coordinate of the lens unit on the x-axis, y n represents the coordinate of the lens unit on the y-axis, k0 is the free space wave number in vacuum, R i represents the distance from the phase center of the feed to the i-th lens unit, represents the main beam direction, where θ represents the elevation angle of the beam, represents the azimuth angle of the beam.

6. The dielectric lens according to claim 1, characterized in that, The dielectric lens is fabricated by the 3D printing method.

7. The dielectric lens according to claim 1 or 6, characterized in that, The dielectric constant of the dielectric lens is 4.4, and the tangent of the loss angle is 0.

004.

8. A dielectric lens antenna, characterized in that, This dielectric lens antenna includes the dielectric lens (1) as described in Claim 1 and a feed antenna (2). The feed antenna (2) is arranged on one side of the dielectric lens (1) and is located on the extension line of the geometric center of the dielectric lens (1).

9. The dielectric lens antenna according to claim 8, wherein, The feed antenna is a standard gain horn antenna in the Ka band.

10. The dielectric lens antenna according to claim 8, characterized in that, The focal length of the dielectric lens antenna is 78.4 mm, and the focal diameter ratio of the dielectric lens antenna is 0.8.

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