Broadband wide-angle scanning array antenna based on metasurface lens

Abstract

The invention discloses a broadband wide-angle scanning array antenna based on a metasurface lens, belongs to the technical field of phased-array antennas, solves the problem of how to improve the scanning range and gain of the phased-array antennae, and is characterized in that the metasurface lens with phase gradient is loaded above the phased-array antenna on the basis of not changing the structure of the original phased-array antenna. The beam scanning range of the phased-array antenna is expanded, and the performance such as gain is improved; according to the invention, an original phased-array antenna does not need to be modified and redesigned, additional active devices do not need to be added, new components do not need to be introduced into an original system, the system cost is effectively reduced, the system size is reduced, and the antenna is suitable for scenes, such as unmanned aerial vehicles and low-altitude aircrafts, which have strict requirements on the size and the weight.

Description

Technical Field

[0001] The present invention belongs to the technical field of phased array antennas and relates to a wide-bandwidth and wide-angle scanning array antenna based on a metasurface lens. Background Art

[0002] In the low-altitude economy, the performance of communication and monitoring systems is directly related to the efficient utilization and safety of low-altitude airspace. Phased array antennas (PAAs), as an advanced antenna technology, electronically change the phase of the signal to achieve flexible control of the direction of the electromagnetic wave beam. With advantages such as fast scanning, high gain, and anti-interference, they have become an indispensable core technology in the low-altitude economy. In low-altitude economy scenarios, applications such as drone logistics, low-altitude transportation, and agricultural monitoring require communication and radar systems with wide-angle scanning capabilities. Wide-angle scanning performance requires antennas to cover a wider angle range to adapt to complex and changing flight environments, reduce blind spots, and improve system efficiency and reliability. For example, in drone formation flying or low-altitude traffic management, the system needs to monitor and communicate targets in multiple directions in real time, and wide-angle scanning performance ensures efficient signal transmission and target detection over a wider angle range.

[0003] Currently, wide-angle scanning technology has some limitations in practical applications. First, as the scanning angle increases, the gain and efficiency of the antenna will significantly decrease, resulting in a degradation of communication or radar performance. Existing technologies modify the elements and array factors of the phased array by iteratively optimizing parameters such as antenna elements, array distribution, and feed structure to increase the scanning range of the antenna. For example, the literature (Wen YQ, Wang BZ, Ding X. AWide-Angle Scanning and Low Sidelobe Level Microstrip Phased Array Based on Genetic Algorithm Optimization [J]. IEEE Transactions on Antennas and Propagation, 2016, 64(2): 1-1. DOI: 10.1109 / TAP.2015.2507173.) discloses a new microstrip phased array based on microstrip magnetic dipoles. Microstrip magnetic dipoles are used as driving elements in the phased array. At the same time, coupling patches are embedded between adjacent driving elements, and coupling energy is transferred between the driving elements through the coupling patches. However, these methods require a lot of computing resources and time and are not suitable for situations where the antenna platform is fixed.

[0004] Secondly, traditional phased array antennas require a large number of array elements and complex signal processing circuits, resulting in high design and manufacturing costs and large size, making them difficult to apply to scenarios with strict weight and space requirements, such as drones or light aircraft. For example, the literature (Liu K, Yang S, Qu SW, et al. Phased Hemispherical Lens Antenna for 1-D Wide-Angle Beam Scanning [J]. IEEE Transactions on Antennas and Propagation, 2019, PP(99): 1-1. DOI: 10.1109 / TAP.2019.2934815.) discloses a Ka-band hemispherical lens antenna fed by a phased array antenna. The design of a hemispherical lens antenna with two dielectric layers can reduce computational complexity without sacrificing accuracy. However, the lens is manufactured using 3D printing technology, resulting in an increased size. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to improve the scanning range and gain of a phased array antenna.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] A wide-bandwidth angular scanning array antenna based on a metasurface lens, comprising a metasurface lens and a phased array antenna arranged sequentially from top to bottom;

[0008] The metasurface lens includes a plurality of metasurface units; the metasurface units include a first metal layer, a first dielectric substrate, a second metal layer, a second dielectric substrate, and a third metal layer, which are sequentially arranged from top to bottom; the first metal layer, the second metal layer, and the third metal layer are provided with the same metal structure; the metal structure includes a rectangular metal element and a semicircular metal element, the rectangular metal element is arranged at the center of the first metal layer, and the straight sides of the plurality of semicircular metal elements are respectively connected to the straight sides of the rectangular metal element to form an integrated structure, forming a four-leaf clover structure;

[0009] The phased array antenna includes an antenna unit and an antenna dielectric plate, wherein a plurality of the antenna units are arranged on the upper surface of the antenna dielectric plate, and a metal floor is provided on the lower surface of the antenna dielectric plate; the antenna unit includes a radiation patch and a feeding point, wherein the radiation patch is arranged on the upper surface of the antenna dielectric plate, and a U-shaped gap is opened in the radiation patch, and the feeding point is arranged at the opening of the U-shaped gap, passes through the antenna dielectric plate and is connected to the metal floor.

[0010] Furthermore, the first metal layer, the first dielectric substrate, the second metal layer, the second dielectric substrate and the third metal layer are arranged in parallel, and vertical projections of the metal structures arranged in the first metal layer, the second metal layer and the third metal layer completely overlap in the vertical direction.

[0011] Furthermore, the thickness of the first dielectric substrate is the same as that of the second dielectric substrate. The first dielectric substrate and the second dielectric substrate are made of Rogers 6002, with a relative dielectric constant of 2.94, a loss tangent of 0.0012, and a size of 10×10×1.5 mm. 3 .

[0012] Furthermore, the diagonal length of the rectangular metal element is 2r1, the radius of the semicircular metal element is r2, and the diameter of the semicircular metal element is equal to the side length of the rectangular metal element, satisfying

[0013] Furthermore, the parameter r1 of the rectangular metal element has a value range of 1.5 to 3.7 mm.

[0014] Furthermore, the metasurface lens is composed of 12×12 metasurface units, and the metasurface units with different transmission phases are arranged in a radial cyclic manner.

[0015] Furthermore, the metasurface lens is arranged in parallel with the phased array antenna, and the distance between the lower surface of the metasurface lens and the upper surface of the phased array antenna is two wavelengths.

[0016] Furthermore, the antenna dielectric plate is made of Rogers 6002, with a relative dielectric constant of 2.94 and a thickness of 1.5 mm.

[0017] Furthermore, the phased array antenna is composed of 4×4 antenna units and is powered by 16 SMA connectors, and each antenna unit is excited by a coaxial feed with an inner diameter of 0.6 mm and an outer diameter of 1.4 mm.

[0018] The advantages of the present invention are:

[0019] (1) The present invention expands the beam scanning range of the phased array antenna and improves performance such as gain by loading a metasurface lens with a phase gradient above the phased array antenna without changing the original phased array antenna structure. The present invention does not require modification or redesign of the original phased array antenna, nor does it involve adding additional active devices. There is no need to introduce new components into the original system, which effectively reduces system cost and system volume, and has superior physical size and electrical performance.

[0020] (2) Based on the generalized Snell's law, the present invention proves that a metasurface lens with a phase gradient can manipulate the incident wave to achieve the desired refraction angle. By loading the metasurface lens and adjusting the phase distribution of the transmitted wave, the scanning range of the two-dimensional phased array antenna is expanded. The transmission amplitude from 0° to 360° at a frequency of 10 GHz can exceed 0.8. By utilizing a large range of transmission phase exceeding 360°, the transmission phase difference is maintained below 34° within the oblique incidence angle range of 0° to 60°. Experimental results show that the scanning angle increases from +48° to +75° (an increase of 56%) on the E plane and from ±42° to ±71° (an increase of 59%) on the H plane.

[0021] (3) This solution loads a metasurface lens with a phase gradient above the phased array antenna. The metasurface lens can break through the mechanical limitations of traditional antennas and achieve a wider scanning range. At the same time, the metasurface lens can optimize the propagation path of electromagnetic waves and reduce energy loss, thereby improving the efficiency and gain of the antenna, especially in wide-angle scanning. As a planar structure, the metasurface lens does not require complex mechanical adjustments or a large number of array elements, which significantly reduces the design and manufacturing costs of the antenna, making the entire antenna system more compact and significantly reducing the weight. It is suitable for scenarios such as drones and low-altitude aircraft that have strict requirements on volume and weight, and provides a more efficient and flexible technical solution for communication and monitoring systems in the low-altitude economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is an overall structural diagram of a wide bandwidth and angle scanning array antenna based on a metasurface lens according to a first embodiment of the present invention;

[0023] Figure 2 Schematic diagram of metasurface units with different transmission phases according to the first embodiment of the present invention;

[0024] Figure 3 is a structural diagram of an antenna unit according to a first embodiment of the present invention;

[0025] Figure 4 (a) is a side view of the metasurface unit according to the first embodiment of the present invention;

[0026] Figure 4 (b) is a top view of the metasurface unit according to the first embodiment of the present invention;

[0027] Figure 5 (a) is a schematic diagram of a plane wave incident on a metasurface unit according to the first embodiment of the present invention;

[0028] Figure 5 (b) is a top view of the metasurface unit according to the first embodiment of the present invention;

[0029] Figure 5 (c)~ Figure 5 (e) is a schematic diagram of the simulated electric field distribution when a plane wave is incident on a metasurface unit at angles of 0°, 20°, and 30°, respectively, according to the first embodiment of the present invention;

[0030] Figure 6 (a) is a schematic diagram of the scanning beam test results of the phased array antenna in Example 1 of the present invention when subjected to +89° phase gradient feeding and loaded with a metasurface;

[0031] Figure 6 (b) is a schematic diagram of the scanning beam test results of the phased array antenna in Example 1 of the present invention when the -89° phase gradient feeding is performed and the metasurface is loaded;

[0032] Figure numerals: 1. First metal layer; 2. First dielectric substrate; 3. Antenna unit; 4. Antenna dielectric plate; 5. First metasurface unit; 6. Second metasurface unit; 7. Third metasurface unit; 8. Fourth metasurface unit; 9. Fifth metasurface unit; 10. Sixth metasurface unit; 11. Radiation patch; 12. U-shaped gap; 13. Feeding point; 14. Second metal layer; 15. Second dielectric substrate; 16. Third metal layer. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] The technical solution of the present invention is further described below with reference to the accompanying drawings and specific embodiments:

[0035] Example 1

[0036] like Figure 1 As shown, specifically, a wide bandwidth and angle scanning array antenna based on a metasurface lens is disclosed, including a metasurface lens and a phased array antenna arranged in sequence from top to bottom.

[0037] The metasurface lens includes multiple metasurface units; the metasurface unit includes a first metal layer 1, a first dielectric substrate 2, a second metal layer 14, a second dielectric substrate 15 and a third metal layer 16 arranged in sequence from top to bottom; the first metal layer 1, the second metal layer 14 and the third metal layer 16 are provided with the same metal structure; taking the first metal layer 1 as an example, the metal structure includes a rectangular metal element and a semicircular metal element, the rectangular metal element is arranged at the center position of the first metal layer 1, and the straight sides of the four semicircular metal elements are respectively connected to the four sides of the rectangular metal element to form an integrated structure, forming a four-leaf clover structure.

[0038] like Figure 4 As shown, the rectangular metal element can be a square metal element with a side length of The diagonal length is 2r1, the radius of the semicircular metal element is r2, and the diameter of the semicircular metal element is equal to the side length of the rectangular metal element, satisfying This embodiment changes the size of the metal structure by changing the key parameter r1 of the metal structure, thereby adjusting the phase of the transmission wave. When the operating frequency is 10 GHz, the value range of r1 is 1.5 to 3.7 mm.

[0039] like Figure 2 As shown, by increasing the value of r1 in sequence, the transmission phase can be adjusted to 0°, -60°, -120°, -180°, -240° and -300° (the phase difference is 60°). Specifically, when the value of r1 is 1.5mm, it corresponds to the first metasurface unit 5 with a transmission phase of 0°; when the value of r1 is 2.3mm, it corresponds to the second metasurface unit 6 with a transmission phase of -60°; when the value of r1 is 2.8mm, it corresponds to the third metasurface unit 7 with a transmission phase of -120°; when the value of r1 is 3.2mm, it corresponds to the fourth metasurface unit 8 with a transmission phase of -180°; when the value of r1 is 3.7mm, it corresponds to the fifth metasurface unit 9 with a transmission phase of -240°; and when the value of r1 is 1.5mm, it corresponds to the sixth metasurface unit 10 with a transmission phase of -300°. Figure 1 As shown, the metasurface lens is composed of at least 12×12 metasurface units, and the metasurface units with different transmission phases are arranged in a radial cyclic manner.

[0040] Furthermore, the first metal layer 1, the first dielectric substrate 2, the second metal layer 14, the second dielectric substrate 15 and the third metal layer 16 are arranged in parallel, the first dielectric substrate 2 and the second dielectric substrate 15 have the same thickness, and the metal structure of the first metal layer 1, the second metal layer 14 and the third metal layer 16 is arranged in a vertical direction ( Figure 1 The vertical projections on the z-axis (corresponding to the center) completely coincide with each other.

[0041] Furthermore, the metal structure can be provided on the dielectric substrate in the form of copper cladding or metal patch, the first dielectric substrate 2 and the second dielectric substrate 15 are laminated with a prepreg, and the second metal layer 14 is provided on the first dielectric substrate 2 .

[0042] In this embodiment, if Figure 4 As shown, the thickness h1 of the first dielectric substrate 2 (layer A) is the same as the thickness h2 of the second dielectric substrate 15 (layer B). The first dielectric substrate 2 and the second dielectric substrate 15 can be made of Rogers 6002, which has a relative dielectric constant of 2.94 and a loss tangent of 0.0012. The size of the dielectric substrate can be 10×10×1.5 mm. 3 .

[0043] like Figure 4 As shown, there is still an unetched area on the dielectric substrate, which is The four sides of the square area are connected to the straight sides of the four semicircular areas to form an integrated structure, satisfying the relationship Among them, rr1 is 3.8mm.

[0044] The phased array antenna includes an antenna unit 3 and an antenna dielectric plate 4, wherein a plurality of the antenna units 3 are arranged on the upper surface of the antenna dielectric plate 4, and a metal floor is provided on the lower surface of the antenna dielectric plate 4; the antenna unit 3 includes a radiation patch 11 and a feeding point 13, wherein the radiation patch 11 is arranged on the upper surface of the antenna dielectric plate 4, and the radiation patch 11 is provided with a U-shaped gap 12, and the feeding point 13 is arranged at the opening of the U-shaped gap 12, passes through the antenna dielectric plate 4 and is connected to the metal floor.

[0045] like Figure 1 and Figure 3 As shown, the phased array antenna is composed of at least 4×4 antenna elements 3 and is powered by 16 SMA connectors. Each antenna element 3 is excited by a coaxial feed with an inner diameter Rin = 0.6 mm and an outer diameter Rout = 1.4 mm. The SMA connector is connected to a power switch through a coaxial cable. The radiation performance of the phased array antenna can be effectively evaluated using a planar near-field test method.

[0046] Furthermore, the metasurface lens is arranged in parallel with the phased array antenna, and the distance between the lower surface of the metasurface lens and the upper surface of the phased array antenna is two wavelengths. Figure 1 As shown in the figure, the distance D between the metasurface lens and the phased array antenna can be 55 mm, the operating frequency is 10.5 GHz, and the scanning range of the phased array antenna after loading the metasurface lens can be expanded from (-45°, +45°) to (-74°, +75°), and the maximum gain is increased by 1.6 dB.

[0047] In this embodiment, the antenna dielectric plate 4 may be made of Rogers 6002, which has a relative dielectric constant of 2.94 and a thickness of 1.5 mm.

[0048] Working principle:

[0049] The present invention is based on the generalized Snell's law as follows:

[0050]

[0051] Where θ t_cal is the angle between the transmitted electromagnetic wave and the normal, θ i is the angle between the incident electromagnetic wave and the normal, n t and n i are the relative permittivities of the incident and exiting media, λ0 is the wavelength of the electromagnetic wave, and ΔΦ / Δx is the phase gradient in the incident plane.

[0052] The generalized Snell's law shows that the deflection angle of the transmitted electromagnetic wave is not only related to the dielectric constant of the medium, but also to the phase gradient of the incident wave plane. Therefore, the present invention can use the transmission-type metasurface to achieve a change in the phase gradient of the incident plane, thereby deflecting the transmitted electromagnetic wave, that is, expanding the scanning beam range, and effectively solving the problems of limited scanning angle and reduced gain of phased array antennas.

[0053] In order to evaluate the wave deflection performance of the metasurface lens, HFSS software was used to simulate the metasurface lens with phase gradient distribution, as shown in Figure 5 (a)~ Figure 5 (b) The metasurface lens is surrounded by a periodic boundary, which can be regarded as equivalent to an infinite phase gradient boundary. In addition, the metasurface lens includes six metasurface units with transmission phases, which generate transmission phases of 0°, -60°, -120°, -180°, -240°, and -300°, respectively, corresponding to Figure 5 In addition, when the linearly polarized plane wave is incident on the proposed metasurface unit at an angle of 0°, 20°, and 30°, the above generalized Snell's law is used to calculate, where ΔΦ and Δx are taken as 60° and 10 mm respectively; assuming that the thickness of the metasurface unit in free space can be ignored, take n i =n t =1, and the theoretical value θ is obtained t_cal They are 30°, 57.4° and 90° respectively, and Figure 5 (c)~ Figure 5The simulated electric field distribution shown in (e) matches the actual value very well. In addition, the simulation results also confirm the effective performance of the proposed metasurface lens in manipulating the transmission phase of incident light beams with a wide spectrum.

[0054] The actual scanning extension range should always deteriorate with increasing incident angles due to the modulation capability of the metasurface lens at different incident angles. Therefore, the distance between the phased array antenna and the metasurface lens must be optimized to make the beam expansion results as efficient as possible. Considering the extended range of scanning angles and radiation efficiency, the present invention optimizes the spacing between the metasurface lens and the phased array antenna to 55mm.

[0055] like Figure 6 As shown in (a), the phased array antenna is fed with a phase difference of +89° along the +x axis. Without the metasurface lens, it can scan to -45° on the xoz surface. After loading the metasurface lens, the scanning angle can be extended to -74°.

[0056] like Figure 6 As shown in (b), the phased array antenna is fed with a phase difference of -89° along the +x axis. Without the metasurface lens, it can scan to +45° on the xoz surface. After loading the metasurface lens, the scanning angle can be extended to +75°.

[0057] In summary, the scanning range of the phased array antenna on the xoz plane is expanded from (-45°, +45°) to (-74°, +74°), and the scanning range is expanded by 64.4%.

[0058] At the same time, the electrical performance of the phased array antenna is shown in Table 1 below. It can be seen that after loading the metasurface lens (indicated as loading MS in Table 1), the maximum gain of the phased array antenna 3 is increased by 1.6 dB.

[0059] Table 1 Electrical performance of array antenna

[0060]

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A wide bandwidth and angular scanning array antenna based on a metasurface lens, characterized in that: It includes a metasurface lens and a phased array antenna arranged in sequence from top to bottom; The metasurface lens includes a plurality of metasurface units; the metasurface units include a first metal layer, a first dielectric substrate, a second metal layer, a second dielectric substrate, and a third metal layer, which are sequentially arranged from top to bottom; the first metal layer, the second metal layer, and the third metal layer are provided with the same metal structure; the metal structure includes a rectangular metal element and a semicircular metal element, the rectangular metal element is arranged at the center of the first metal layer, and the straight sides of the plurality of semicircular metal elements are respectively connected to the straight sides of the rectangular metal element to form an integrated structure; The phased array antenna includes an antenna unit and an antenna dielectric plate, wherein a plurality of the antenna units are arranged on the upper surface of the antenna dielectric plate, and a metal floor is provided on the lower surface of the antenna dielectric plate; the antenna unit includes a radiation patch and a feeding point, wherein the radiation patch is arranged on the upper surface of the antenna dielectric plate, and a U-shaped gap is opened in the radiation patch, and the feeding point is arranged at the opening of the U-shaped gap, passes through the antenna dielectric plate and is connected to the metal floor.

2. The wide bandwidth and angle scanning array antenna based on a metasurface lens according to claim 1, characterized in that: The first metal layer, the first dielectric substrate, the second metal layer, the second dielectric substrate and the third metal layer are arranged in parallel, and vertical projections of the metal structures arranged in the first metal layer, the second metal layer and the third metal layer completely overlap in the vertical direction.

3. The wide bandwidth and angle scanning array antenna based on a metasurface lens according to claim 1, characterized in that: The thickness of the first dielectric substrate is the same as that of the second dielectric substrate. The first dielectric substrate and the second dielectric substrate are made of Rogers 6002, with a relative dielectric constant of 2.94, a loss tangent value of 0.0012, and a size of 10×10×1.5 mm. 3 .

4. The wide bandwidth and angle scanning array antenna based on a metasurface lens according to claim 1, characterized in that: The diagonal length of the rectangular metal element is 2r1, the radius of the semicircular metal element is r2, and the diameter of the semicircular metal element is equal to the side length of the rectangular metal element, satisfying 5. The wide bandwidth and angle scanning array antenna based on a metasurface lens according to claim 4, characterized in that: The parameter r1 of the rectangular metal element has a value range of 1.5 to 3.7 mm.

6. The wide bandwidth and angle scanning array antenna based on a metasurface lens according to claim 1, characterized in that: The metasurface lens is composed of 12×12 metasurface units, and the metasurface units with different transmission phases are arranged in a radial cyclic manner.

7. The wide bandwidth and angle scanning array antenna based on a metasurface lens according to claim 1, characterized in that: The metasurface lens is arranged in parallel with the phased array antenna, and the distance between the lower surface of the metasurface lens and the upper surface of the phased array antenna is two wavelengths.

8. The wide bandwidth and angle scanning array antenna based on a metasurface lens according to claim 1, characterized in that: The antenna dielectric plate is made of Rogers 6002, with a relative dielectric constant of 2.94 and a thickness of 1.5 mm.

9. The wide bandwidth and angle scanning array antenna based on a metasurface lens according to claim 1, characterized in that: The phased array antenna is composed of 4×4 antenna units and is powered by 16 SMA connectors. Each antenna unit is excited by a coaxial feed with an inner diameter of 0.6 mm and an outer diameter of 1.4 mm.

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