A three-frequency antenna based on double-layer metasurface

Abstract

The application discloses a kind of three-frequency antennas based on double-layer metasurface, belong to microwave antenna technical field.The antenna uses multilayer stacking structure, from top to bottom sequentially include first metasurface layer, feed layer, second metasurface layer and metal ground plate.First metasurface layer is composed of square ring patch and 4×4 rectangular array arranged in its interior, the array contains two different sizes square patch.Feed layer includes slot patch and feed microstrip line, slot patch adopts composite slot design, it is equipped with square defect in the center, and square ring slot is engraved on the periphery, and electrical connection is realized by two connecting points;Feed microstrip line adopts special configuration, and forms convex-shaped coupling area with slot patch.Second metasurface layer is composed of multiple square patches and forms 5×5 rectangular array.The application has the advantages of compact structure and stable radiation through the synergistic electromagnetic regulation and control of double-layer metasurface, and can meet the demand of multi-frequency band compatibility and multi-polarization adaptation for 5G millimeter wave communication.

Description

Technical Field

[0001] This invention relates to the field of microwave antenna technology, specifically a tri-band antenna based on a double-layer metasurface, suitable for scenarios such as 5G millimeter-wave high-speed data transmission, 5G millimeter-wave base stations, and millimeter-wave communication terminals. Background Technology

[0002] As 5G communication expands into millimeter-wave bands, the requirements for antennas in communication systems—namely, multi-band coverage, multi-polarization adaptation, and high radiation stability—are increasingly stringent. Metasurface-based tri-band antennas, due to their ability to extend frequency bands and optimize polarization through the electromagnetic modulation properties of metasurfaces, have become an important development direction for 5G millimeter-wave antennas. However, existing antennas of this type have the following technical limitations:

[0003] Existing metasurface-based tri-band antennas can only achieve single-band polarization, failing to simultaneously cover the multi-scenario requirements of "linear polarization + dual-band circular polarization." Furthermore, some designs, while attempting multi-polarization, suffer from unstable polarization characteristics due to improper electromagnetic coupling control between the metasurface and the feed layer. To address these shortcomings, there is an urgent need to optimize the double-layer metasurface structure and feed design to achieve tri-band antennas with "three-band impedance matching, dual-band circular polarization, and stable high-frequency radiation." Summary of the Invention

[0004] In view of this, the present invention discloses a tri-band antenna based on a double-layer metasurface. Employing a design scheme of "composite structure + double-layer metasurface synergistic control," the antenna achieves impedance matching across the 15-19 GHz band, dual-band circular polarization radiation, and stable directional radiation through electromagnetic coupling and parameter matching of each layer, thus meeting the core requirements of 5G millimeter-wave communication for multi-band compatibility and multi-polarization adaptation.

[0005] To achieve the above functions, the specific implementation scheme of the present invention is as follows:

[0006] A tri-band antenna based on a double-layer metasurface includes a first metasurface layer, a feed layer, a second metasurface layer, and a metal ground plane arranged sequentially from top to bottom;

[0007] The first metasurface layer includes a first square patch, a second square patch, and a square ring patch; the first square patch and the second square patch together form a 4×4 rectangular array; the 4×4 array is located in the square ring patch and does not contact the square ring patch, and the first square patch is located in the area enclosed by multiple second square patches.

[0008] The feed layer includes a slotted patch and a feed microstrip line; the main structure of the slotted patch is square, with square annular slots on it; on the slotted patch, two parts separated by the square annular slots are connected by two connection points, which are located on two adjacent slots of the square annular slots; the feed microstrip line is connected to the outside of the slotted patch; the center of the slotted patch also has a square defect.

[0009] The second metasurface layer includes multiple third-dimensional patches; the multiple third-dimensional patches form a 5×5 rectangular array.

[0010] Furthermore, the side length of the first square patch is greater than the side length of the second square patch, and the side length of the second square patch is greater than the side length of the third square patch; there are a total of four first square patches and a total of twelve second square patches; the four first square patches are located within the area enclosed by the twelve second square patches.

[0011] Furthermore, the center of the 4×4 rectangular array is offset from the center of the square ring patch.

[0012] Furthermore, the power-fed microstrip line includes a loop segment and a straight segment; wherein the loop segment is connected to the slotted patch and the two form a convex region, and the head of the convex region is attached to the slotted patch; the straight segment is connected to the tail of the convex region.

[0013] Furthermore, the first metasurface layer and the power feed layer are located on the upper and lower surfaces of the upper dielectric substrate, respectively; the second metasurface layer and the metal ground plane are located on the upper and lower surfaces of the lower dielectric substrate, respectively; the middle dielectric substrate is located between the power feed layer and the second metasurface layer; the upper and lower dielectric substrates are F4BM220, and the middle dielectric substrate is FR-28.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. The dual-layer metasurface coupling structure of this invention enables the antenna to achieve stable linear polarization in the 15.23-15.83 GHz frequency band, meeting the requirements of conventional millimeter-wave data transmission scenarios; and stable circular polarization in the 17.3-17.5 GHz and 17.92-18.07 GHz frequency bands. The circular polarization in the 17.3-17.5 GHz band originates from the triple electromagnetic coupling between the square ring patch of the first metasurface layer, the feed layer, and the second metasurface layer; the circular polarization in the 17.92-18.07 GHz band originates from the synergistic effect of the dual metasurface layers. The dual-band circular polarization can be adapted to complex communication scenarios such as satellite communication and multipath interference resistance.

[0016] 2. The antenna of this invention adopts a multi-layer patch integrated design, and the overall thickness depends on the number of dielectric substrate layers. (It has a compact structure and light weight, and can be directly integrated into 5G millimeter wave base station antenna arrays or miniaturized terminal devices, adapting to the miniaturization design requirements of 5G millimeter wave devices.) Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 This is a schematic diagram of the dimensions of the feed layer in an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the feed layer structure according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram showing the dimensions of the first metasurface layer in an embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the structure of the first metasurface layer in an embodiment of the present invention.

[0022] Figure 5 This is a schematic diagram of the dimensions and structure of the second metasurface layer according to an embodiment of the present invention.

[0023] Figure 6 This is a structural side view of an embodiment of the present invention.

[0024] Figure 7 This is the impedance matching S11 curve of the antenna in the embodiment.

[0025] Figure 8 This is a graph showing the axial ratio of the antenna in the embodiment.

[0026] In the diagram: 1. Slotted patch, 2. Feed microstrip line, 3. Lower dielectric substrate, 4. Square ring patch, 5. 4×4 rectangular array, 6. Third square patch, 7. Upper dielectric substrate, 8. Metal ground plane, 9. Middle dielectric substrate, 1-1. Square ring slot, 1-2. Square defect, 1-3. Connection, 2-1. Ring segment, 2-2. T-shaped area, 2-3. Straight segment, 5-1. Second square patch, 5-2. First square patch. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0028] The tri-band antenna in this embodiment employs a vertically stacked design of a four-layer metal structure and a three-layer dielectric substrate. From top to bottom, the layers are: a first metasurface layer, an upper dielectric substrate 7, a feed layer, a middle dielectric substrate 9, a second metasurface layer, a lower dielectric substrate 3, and a metal ground plane 8. Each layer is precisely aligned to form a complete electromagnetic radiation system.

[0029] The first metasurface layer is integrated on the upper surface of the upper dielectric substrate 7, and its core consists of a square ring patch 4 and a built-in 4×4 rectangular array 5. This 4×4 rectangular array 5 is composed of twelve second square patches 5-1 and four first square patches 5-2 arranged according to a specific pattern, with the four first square patches 5-2 located in the central region of the array and surrounded by the twelve second square patches 5-1. Notably, the overall position of the 4×4 rectangular array 5 is offset relative to the center of the square ring patch 4; this asymmetrical layout is key to generating circularly polarized radiation. In terms of dimensions, the first square patches 5-2 have a side length of 0.96 mm, the second square patches 5-1 have a side length of 0.89 mm, and the outer contour side length of the square ring patch 4 is 6.1 mm. The spacing between the components is precisely calculated to achieve optimal coupling.

[0030] The feed layer is fabricated on the lower surface of the upper dielectric substrate 7 and comprises two main components: a slotted patch 1 and a feed microstrip line 2. The slotted patch 1 employs a composite slotting design, with a square defect 1-2 at its center and a square annular groove 1-1 etched around its perimeter, dividing the patch into inner and outer conductive regions. These two regions are electrically connected through two connection points 1-3 located on adjacent sides of the square annular groove. The feed microstrip line 2 adopts a special configuration, consisting of a loop segment 2-1 and a straight segment 2-3, where the loop segment 2-1 and the outer edge of the slotted patch 1 together form a convex region 2-2. This unique feed structure can effectively control the surface current distribution and achieve impedance matching across three operating frequency bands.

[0031] The second metasurface layer is disposed on the upper surface of the lower dielectric substrate 3 and consists of twenty-five third-party triangular patches 6 arranged in a 5×5 rectangular array. Each third-party triangular patch 6 has a side length of 0.98 mm and an array period of 1.8 mm × 1.8 mm. This layer acts as a parasitic resonator, and its projection range completely covers the 4×4 rectangular array 5 of the upper layer. Through precise size design and spacing control, it forms a strong electromagnetic coupling with the upper structure.

[0032] The support structure employs three dielectric substrates to achieve interlayer isolation and electromagnetic coupling adjustment. The upper dielectric substrate 7 and the lower dielectric substrate 3 are both made of F4BM220 material, with a thickness of 0.8 mm, a dielectric constant of 2.2, and a loss tangent of 0.007. The middle dielectric substrate 9 is made of FR-28 material, with a thickness of 0.5 mm, a dielectric constant of 2.8, and a loss tangent of 0.0035. The special parameters of this layer are designed to optimize the electromagnetic coupling strength between the two metasurface layers.

[0033] The metal ground plane 8 is fabricated on the lower surface of the lower dielectric substrate 3 and serves as the reflective surface of the antenna. This not only enhances the directional radiation capability of the antenna but also effectively suppresses back radiation, thereby improving the antenna's front-to-back ratio and gain stability.

[0034] Reference Figure 1, Figure 3 and Figure 5 The structural dimensions (the following data are in millimeters) are as follows: a is 1.8; b is 1; c is 0.4; d is 6.2; e is 4.8; f is 0.5; g is 6.1; h is 3.7; i is 12; j is 0.8; k is 1; l is 6.1; m is 0.89; n is 0.96; o is 0.98.

[0035] Regarding the antenna's operating mechanism, the three-band operating characteristics are achieved through the synergistic effect of each layer of the structure. In the 15.23-15.83 GHz band, stable linear polarization radiation is mainly achieved through the combined effect of the fundamental resonance of the slotted patch 1 and the coupled resonance of the square ring patch 4. In the 17.3-17.5 GHz band, the asymmetric structural design of the first metasurface layer causes a 90° phase difference in the surface current, which, together with the excitation of the feed layer, realizes the first circular polarization radiation band. In the 17.92-18.07 GHz band, the strong coupling effect of the double metasurface layers generates the second circular polarization radiation band, in which the higher-order resonant modes of the 5×5 rectangular array 6 play a key role in expanding the bandwidth.

[0036] Experimental results show that the antenna exhibits a return loss of less than -10dB across all three target frequency bands, demonstrating excellent impedance matching. In the two circularly polarized frequency bands, the axial ratio is less than 3dB, and the radiation characteristics are stable. The antenna's overall structure is compact, with a total thickness of only 2.1 mm, making it ideal for the miniaturization and integration requirements of 5G millimeter-wave base stations and terminal equipment.

[0037] This invention proposes a tri-band antenna based on a dual-layer metasurface, specifically designed for 5G millimeter-wave high-speed data transmission, 5G millimeter-wave base stations, and millimeter-wave communication terminals. Covering the 15-19 GHz frequency band, it achieves three-band impedance matching, dual-band circular polarization radiation, and stable directional radiation. Addressing the shortcomings of existing antenna technologies in multi-band coverage and multi-polarization adaptation, this invention employs a "four-layer composite structure + dual-layer metasurface synergistic control" scheme. Through the integrated design of slotted patches, dual-layer metasurfaces, and a metal ground plane, electromagnetic coupling and parameter matching are optimized.

[0038] The antenna achieves stable linear polarization in the 15.23-15.83GHz band and stable circular polarization in the 17.3-17.5GHz and 17.92-18.07GHz bands, meeting the needs of complex communication scenarios. Simultaneously, the antenna has a compact structure and is lightweight, allowing for direct integration into 5G millimeter-wave devices, aligning with the trend towards miniaturization.

Claims

1. A tri-band antenna based on double-layer metasurface, characterized in that, The first metasurface layer, the feeding layer, the second metasurface layer and the metal ground plane (8) are sequentially arranged from top to bottom. The first metasurface layer comprises a first square patch (5-2), a second square patch (5-1) and a square ring patch (4); the first square patch (5-2) and the second square patch (5-1) jointly constitute a 4*4 rectangular array (5); the 4*4 rectangular array (5) is located in the square ring patch (4) and is in contact with the square ring patch (4), and the first square patch (5-2) is located in an area surrounded by the plurality of second square patches (5-1); The feeding layer comprises a slotted patch (1) and a feeding microstrip line (2); the main structure of the slotted patch (1) is square, and a square ring slot (1-1) is arranged on the slotted patch (1); two parts separated by the square ring slot (1-1) on the slotted patch (1) are connected by two connection points (1-3), and the connection points (1-3) are located on two adjacent slots of the square ring slot (1-1); the feeding microstrip line (2) is connected to the outside of the slotted patch (1); the center of the slotted patch (1) further has a square defect (1-2); The second metasurface layer comprises a plurality of third square patches (6); the plurality of third square patches (6) constitute a 5*5 rectangular array; The side length of the first square patch (5-2) is greater than that of the second square patch (5-1), and the side length of the second square patch (5-1) is greater than that of the third square patch (6); there are four first square patches (5-2) in total, and there are twelve second square patches (5-1) in total; the four first square patches (5-2) are located in an area surrounded by the twelve second square patches (5-1); The center of the 4*4 rectangular array (5) deviates from the center of the square ring patch (4).

2. The tri-band antenna based on double-layer metasurface according to claim 1, characterized in that, The feeding microstrip line (2) comprises a loop segment (2-1) and a straight line segment (2-3); the loop segment (2-1) is connected to the slotted patch (1) and surrounds a convex-shaped area (2-2) with the slotted patch (1), and the head of the convex-shaped area (2-2) is attached to the slotted patch (1); the straight line segment (2-3) is connected to the tail of the convex-shaped area (2-2).

3. The tri-band antenna based on double-layer metasurface according to claim 1, characterized in that, The first metasurface layer and the feeding layer are respectively located on the upper surface and the lower surface of the upper dielectric substrate (7); the second metasurface layer and the metal ground plane (8) are respectively located on the upper surface and the lower surface of the lower dielectric substrate (3); the feeding layer and the second metasurface layer are separated by the intermediate dielectric substrate (9); the upper dielectric substrate (7) and the lower dielectric substrate (3) are F4BM220, and the intermediate dielectric substrate (9) is FR-28.

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