A flat panel capacitively loaded metasurface antenna

Abstract

The application discloses a kind of metasurface antennas based on flat plate capacitance loading in the field of antenna, including first layer dielectric substrate, second layer dielectric substrate and third layer dielectric substrate sequentially stacked from top to bottom;The third layer dielectric substrate bottom is provided with feed network;Metal floor is arranged between the second layer dielectric substrate and the third layer dielectric substrate;Coupling slit is opened in the metal floor;The first layer dielectric substrate is provided with metasurface structure consisting of multiple metasurface units;The metasurface unit includes metasurface patch;Metasurface patch both sides are provided with mutually corresponding metal wall;Energy is input by feed network, coupled to metasurface structure by the coupling slit of metal floor, and the metasurface structure is directed upwards and radiated;While guaranteeing broadband demand, reduce metasurface structure physical size, with compact structure and smooth high-gain characteristics.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to broadband compact antennas. Background Technology

[0002] With the development of modern wireless communication systems, the demand for broadband antennas is increasing. Microstrip patch antennas have attracted widespread attention due to their advantages such as low profile, light weight, low cost, and easy compatibility with printed circuits. However, traditional microstrip patch antennas have narrow impedance bandwidth and low gain. Although there are many technologies to overcome this shortcoming, such as using capacitor probe feeding, L-probe feeding, aperture coupling, U / E slotted patches, and stacked patches, these usually require thick dielectric substrates with low dielectric constants, making it difficult to achieve a low profile.

[0003] Metasurface antennas, which have attracted much attention in recent years, employ periodic patch elements to achieve both low profile and wide bandwidth and good radiation performance. W. Liu et al. proposed an aperture-coupled metasurface antenna that achieved an impedance bandwidth of 28% with a profile of only 0.06λ0. Compared with traditional microstrip patch antennas, metasurface antennas have significant advantages in terms of gain and bandwidth, but their overall size is usually large (~1.1λ0), which leads to certain difficulties in array design and integration.

[0004] Currently, methods for miniaturizing metasurface antennas generally include: employing double / multilayer structures, loading resonant structures, increasing current paths, reducing gaps between elements, and using high-dielectric-constant dielectric substrates. However, these methods typically suffer from problems such as high profile, narrow bandwidth, and limited size reduction. Therefore, how to design compact metasurface antennas while maintaining high performance is a pressing issue that needs to be addressed. Summary of the Invention

[0005] The purpose of this invention is to provide a metasurface antenna based on planar capacitor loading, which reduces the physical size of the metasurface structure while ensuring broadband requirements, and features a compact structure and stable high gain.

[0006] To achieve the above objectives, the technical solution adopted by the present invention in the first aspect is as follows:

[0007] A metasurface antenna based on planar capacitor loading includes a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate stacked sequentially from top to bottom; a feed network is disposed at the bottom of the third dielectric substrate; a metal ground plane is disposed between the second and third dielectric substrates; coupling slots are formed on the metal ground plane; and a metasurface structure composed of multiple metasurface units is disposed on the first dielectric substrate.

[0008] The metasurface unit includes a metasurface patch; the metasurface patch is disposed on the upper surface of the first dielectric substrate; corresponding metal walls are disposed on both sides of the metasurface patch, the metal walls being along the antenna polarization direction; the metal walls are embedded in the first dielectric substrate, and the metal walls are in contact with the metasurface patch; energy is input from the feed network, coupled to the metasurface structure through the coupling gap of the metal ground plane, and the metasurface structure radiates the energy directionally upward.

[0009] Preferably, the multiple metasurface units on the first dielectric substrate are distributed in a rectangular array.

[0010] Preferably, the gap width G1 between the metasurface structural units ranges from [0.001λ0, 0.02λ0].

[0011] Preferably, multiple metal pillars are arranged side by side along the antenna polarization direction to form the metal wall; the multiple metal pillars are embedded in the first dielectric substrate and in contact with the metasurface patch; the length W1 of the metal wall is in the range of [0.05λ0, 0.2λ0], where λ0 is the free space wavelength.

[0012] Preferably, the dielectric constant of the first dielectric substrate is in the range of [2.2, 10.2], and the thickness h2 is in the range of [0.001λ0, 0.05λ0]; the dielectric constant of the second dielectric substrate is in the range of [2.2, 10.2], and the thickness h1 is in the range of [0.001λ0, 0.05λ0]; the dielectric constant of the third dielectric substrate is in the range of [2.2, 10.2], and the thickness h0 is in the range of [0.001λ0, 0.1λ0].

[0013] Preferably, the coupling gap is set as a trapezoid, a rectangle, or a rectangle with serrated sides.

[0014] Preferably, the metal floor is square, and the side length GL ranges from [0.3λ0, λ0]; a rectangular coupling gap is formed on the metal floor, and the length 2×Lss of the coupling gap ranges from [0.1λ0, λ0]. g 0.8λ g The width Ws of the coupling gap ranges from [0.05λ]. g ,0.5λ g ], where λ g This is the effective wavelength of the dielectric substrate in the second layer.

[0015] Preferably, the power supply network is configured as a microstrip metal sheet, and the length of the microstrip metal sheet is in the range of [0.1λ]. g1 0.8λ g1 The width range of the microstrip metal sheet is [0.1λ]. g1 ,0.5λ g1 ], where λg1 This is the effective wavelength of the dielectric material in the third dielectric substrate.

[0016] Preferably, the microstrip metal sheet is configured as Y-shaped, rectangular, or rectangular with serrated sides.

[0017] Preferably, the power supply network is arranged perpendicularly to the coupling gap, and the coupling gap is arranged symmetrically about the centerline of the power supply network.

[0018] Preferably, one or more metal walls are provided on both sides of the metasurface patch; when multiple metal walls are provided on both sides of the metasurface patch, the multiple metal walls on one side of the metasurface patch are arranged side by side.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0020] In this invention, a metasurface structure composed of multiple metasurface units is disposed on the first dielectric substrate. Each metasurface unit includes a metasurface patch. The metasurface patch is disposed on the upper surface of the first dielectric substrate. Corresponding metal walls are disposed on both sides of the metasurface patch, with the metal walls aligned with the antenna polarization direction. The metal walls are embedded within the first dielectric substrate and are in contact with the metasurface patch. This invention reduces the physical size of the metasurface structure while achieving planar capacitor loading, ensuring bandwidth while making the metasurface antenna structure more compact. By selecting a suitable feeding method, the bandwidth of the metasurface antenna can be expanded at a lower profile, ensuring the stable high-gain characteristics of the metasurface antenna.

[0021] In this invention, one or more metal walls are provided on both sides of the metasurface patch; when multiple metal walls are provided on both sides of the metasurface patch, the multiple metal walls on one side of the metasurface patch are arranged in parallel; by arranging multiple metal walls in parallel, the metasurface antenna can be further miniaturized, and the design freedom of the metasurface antenna is improved. Attached Figure Description

[0022] Figure 1 This is a structural diagram of a metasurface antenna based on planar capacitor loading provided by the present invention;

[0023] Figure 2 This is a top view of the first dielectric substrate provided in an embodiment of the present invention;

[0024] Figure 3 This is a structural diagram of the power supply network and coupling seam provided in an embodiment of the present invention;

[0025] Figure 4 This is a cross-sectional view of a metasurface antenna based on planar capacitor loading provided in an embodiment of the present invention;

[0026] Figure 5This is a structural diagram of a conventional square metasurface antenna provided by the present invention;

[0027] Figure 6 This is a cross-sectional view of a conventional square metasurface antenna provided by the present invention;

[0028] Figure 7 This is a structural diagram of the single-fold metasurface structure unit provided by the present invention;

[0029] Figure 8 This is a cross-sectional view of the single-fold metasurface structure unit provided by the present invention;

[0030] Figure 9 This is a structural diagram of the multi-fold metasurface structure unit provided by the present invention;

[0031] Figure 10 This is a cross-sectional view of the multi-fold metasurface structure unit provided by the present invention;

[0032] Figure 11 These are comparative diagrams of various metasurface structural units provided by this invention;

[0033] Figure 12 In this invention Figure 11 A schematic diagram comparing the reflection characteristics of three metasurface unit structures;

[0034] Figure 13 In this invention Figure 11 S of three metasurface unit structures 11 Curve comparison diagram;

[0035] Figure 14 In this invention Figure 11 A comparative diagram of the gain curves of three metasurface unit structures;

[0036] Figure 15 This is the radiation pattern of the metasurface antenna of the single-folded metasurface structure unit in this invention at 6.2 GHz;

[0037] Figure 16 This is the radiation pattern of the metasurface antenna of the single-folded metasurface structure unit in this invention at 7.6 GHz;

[0038] Figure 17 This is the radiation pattern of the metasurface antenna of the single-folded metasurface structure unit in this invention at 8.8 GHz;

[0039] In the figure: 1 Metasurface structure unit, 2 Metasurface patch, 3 Metal ground plane, 4 Coupling gap, 5 Power supply network, 6 Second dielectric substrate, 7 Third dielectric substrate, 8 First dielectric substrate, 9 Metal wall, 10 Metal pillar, 11 Gap, 12 Fan-shaped connection, 13 Metasurface structure, 14 Single-fold metasurface structure unit, 15 Multi-fold metasurface structure unit. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0041] It should be noted that in the description of this invention, the terms "front," "rear," "left," "right," "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "front," "rear," "left," "right," "upper," and "lower" used in the description of this invention refer to the directions shown in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0042] Example 1

[0043] like Figures 1 to 4 As shown, a metasurface antenna based on planar capacitor loading includes a first dielectric substrate 8, a second dielectric substrate 6, and a third dielectric substrate 7 stacked sequentially from top to bottom; the dielectric constant of the first dielectric substrate 8 is in the range of [2.2, 10.2], and the thickness h2 is in the range of [0.001λ0, 0.05λ0]; the dielectric constant of the second dielectric substrate 6 is in the range of [2.2, 10.2], and the thickness h1 is in the range of [0.001λ0, 0.05λ0]; the dielectric constant of the third dielectric substrate 7 is in the range of [2.2, 10.2], and the thickness h0 is in the range of [0.001λ0, 0.1λ0]; λ0 is the free space wavelength.

[0044] A power supply network 5 is provided at the bottom of the third dielectric substrate 7; the power supply network 5 is a microstrip metal sheet, one side of which is connected to the fan-shaped connecting portion 12; the length of the microstrip metal sheet is in the range of [0.1λ]. g1 0.8λ g1 The width range of the microstrip metal sheet is [0.1λ]. g1 ,0.5λ g1 ], where λ g1 The effective wavelength of the dielectric substrate 7 is the third layer; the microstrip metal sheet can be, but is not limited to, Y-shaped, rectangular, or rectangular with serrated sides.

[0045] A metal ground plane 3 is disposed between the second dielectric substrate 6 and the third dielectric substrate 7; the metal ground plane 3 can be, but is not limited to, a square. When the metal ground plane 3 is square, the side length GL of the metal ground plane 3 ranges from [0.3λ0, λ0]; a rectangular coupling gap 4 is formed on the metal ground plane 3, and the length 2×Lss of the coupling gap 4 ranges from [0.1λ0, λ0] to [0.1λ0, λ0]. g 0.8λ g The width Ws of the coupling gap 4 ranges from [0.05λ]. g ,0.5λ g ], where λ g The effective wavelength of the dielectric substrate 6 is the second dielectric layer; the coupling gap 4 can also be set as a trapezoid or a rectangle with serrated sides. The function of the coupling gap 4 is to couple energy to excite the plate capacitor-loaded metasurface structure 13, thereby realizing the broadband miniaturization characteristics of the antenna; through the gap excitation method, the miniaturized metasurface structure radiates, thereby forming a broadband miniaturized metasurface antenna.

[0046] The first dielectric substrate 8 is provided with a plurality of metasurface structure units 1, and the metasurface structure units 1 are arranged in a rectangular array to form a metasurface structure 13; the width G1 of the gap 11 between the metasurface structure units 1 is in the range of [0.001λ0, 0.02λ0].

[0047] The types of metasurface units 1 include single-fold metasurface structure units 14 and multi-fold metasurface structure units 15;

[0048] like Figure 7 and Figure 8 As shown, the single-fold metasurface structure unit 14 includes a metasurface patch 2; the metasurface patch 2 may be, but is not limited to, a square, and the diagonals of the metasurface patch 2 may be chamfered or rounded; the metasurface patch 2 is disposed on the upper surface of the first dielectric substrate 6; each side of the metasurface patch 2 is provided with a single metal wall 9 corresponding to each other to form a planar capacitor, and the metal wall 9 is along the antenna polarization direction; a plurality of metal pillars 10 are arranged side by side along the antenna polarization direction to form the metal wall 9; the plurality of metal pillars 9 are embedded in the first dielectric substrate 6 and are in contact with the metasurface patch 2; the length of the metal wall 9 is in the range of [0.05λ0, 0.2λ0]; thereby enabling the metasurface structure to achieve miniaturization while ensuring broadband bandwidth.

[0049] like Figure 9 and Figure 10As shown, compared with the single-fold metasurface structure unit 14, the multi-fold metasurface structure unit 15 has multiple metal walls 9 on both sides of the metasurface patch 2, and the multiple metal walls 9 on one side of the metasurface patch 2 are arranged side by side.

[0050] Energy is input from the power supply network and coupled to the metasurface structure unit through the coupling gap of the metal floor. The metasurface structure unit radiates the energy upward in a directional manner.

[0051] When the metasurface antenna has a single-port input, it can achieve miniaturization of a single-polarization metasurface antenna; when the metasurface antenna has a dual-port input, it can achieve miniaturization of a dual-polarization metasurface antenna. By setting metal walls on the edges of periodic metasurface patches 2 of different shapes, it is possible to achieve miniaturization of metasurface antennas in different polarization modes. In the case of square metasurface units, it is possible to achieve miniaturization of linearly polarized metasurface antennas. When the metasurface patches 2 have chamfered or rounded corners, it is possible to achieve miniaturization of circularly polarized metasurface antennas.

[0052] Taking the metasurface antenna based on the single-folded metasurface structure unit 14 in the embodiment as an example, such as Figure 7 and Figure 8 As shown, the specific implementation plan and dimensions are as follows:

[0053] The dielectric constant of the first dielectric substrate 8 is 3.55 and the thickness h2 is 1.524 mm; the dielectric constant of the second dielectric substrate 6 is 3.55 and the thickness h1 is 1.524 mm; the dielectric constant of the third dielectric substrate 7 is 3.55 and the thickness h0 is 0.813 mm.

[0054] A single-layer 4×4 square metasurface unit 1 is disposed on the first dielectric substrate 6; the metasurface unit 1 is provided with a metal wall 9 formed by a number of metal pillars 10, realizing the single folding of the physical size of the metasurface structure and forming a planar capacitor; wherein, the metal wall 9 is symmetrically placed along the edges of both sides of the metasurface patch 2, and finally realizing a metasurface structure 13 with broadband miniaturization characteristics and a planar capacitor loading.

[0055] When the polarization of the metasurface antenna is selected as linear polarization along the x-direction at a single port, the metal pillars 10 are distributed along the x-direction to form metasurface units 1. In the metasurface unit 1, the length of the metal wall 9 is W1 = 3 mm, and the width of the gap 11 is G1 = 1 mm. The side length GL of the metal ground plate 3 is 18 mm. The specific dimensions of the rectangular coupling slot 4 opened on the metal ground plate 3 are: Lss = 17 mm, Ws = 0.65 mm. The length of the microstrip metal sheet in the feed network 5 is 13.5 mm, and the width is 1.85 mm.

[0056] like Figures 5 to 10As shown, by comparing the structures of the traditional square metasurface unit with the two planar capacitor-loaded metasurface units obtained by the present invention through different folding methods, it can be found that the traditional square metasurface unit is usually a single-layer structure with a large size and relatively small design freedom; while the metasurface structure in the present invention introduces planar capacitor loading through folding, has a very small size, and a relatively large design freedom.

[0057] Combination Figure 11 , Figure 12 As shown in Table 1, by comparing the reflection characteristics and dimensions of the square metasurface unit structure, the single-fold metasurface unit 14, and the multi-fold metasurface unit 15, it can be found that, while maintaining a basically unchanged center frequency and bandwidth, the structural size required for metasurface unit 1 is significantly reduced compared to the traditional square metasurface unit (overall size 0.154λ0 × 0.154λ0). Specifically, the overall size of the single-fold metasurface unit 14 is 0.075λ0 × 0.075λ0, and the period of the multi-fold metasurface unit 15 is 0.063λ0 × 0.063λ0. These results demonstrate that, compared to the common square metasurface unit, the plate capacitor-loaded metasurface unit 1 of this invention effectively achieves miniaturization of the metasurface structure while maintaining bandwidth.

[0058] Table 1. Parameters of various metasurface unit structures

[0059]

[0060] like Figure 11 , Figure 13 and Figure 14 As shown, a structural comparison of the square metasurface unit structure, the single-fold metasurface unit 14, and the multi-fold metasurface unit 15 reveals that, at the same operating frequency band, the sheet-plate capacitor-loaded metasurface antenna requires a smaller structural size compared to the square metasurface antenna (metasurface structure size is 0.67λ0×0.67λ0). Specifically, the single-fold metasurface unit 14 has a structural size of 0.388λ0×0.388λ0, and the multi-fold metasurface unit 15 has a structural size of 0.356λ0×0.356λ0. Furthermore, compared to the bandwidth (30%) of a common square metasurface antenna, the sheet-plate capacitor-loaded metasurface unit 1 achieves a wider bandwidth.

[0061] Among them, the bandwidth of the metasurface antenna of the single-folded metasurface structure unit 14 is 45.9%, and the bandwidth of the metasurface antenna of the multi-folded metasurface structure unit 15 is 46.9%. These results show that, compared with common square metasurface antennas, the plate-plate capacitor-loaded metasurface antenna of the present invention effectively achieves miniaturization of the metasurface antenna while ensuring bandwidth; at the same time, due to the introduction of the metasurface unit 1, the capacitive loading method is diverse, which increases the design freedom of the overall antenna.

[0062] like Figures 15 to 17 As shown, based on Figure 11 (b) The radiation patterns at various frequency points within the band of the single-folded metasurface structure unit 14 show that its cross-polarization suppression effect is good, reaching about 30dB.

[0063] Referring to Table 2, compared with common square metasurface antennas, the metasurface element 1 of the present invention can effectively reduce the size while ensuring bandwidth; the size of the metasurface element can be reduced to a minimum of 0.356λ0×0.356λ0, and the overall size of the metasurface antenna can be reduced to a minimum of 0.427λ0×0.427λ0, while the bandwidth can be guaranteed to be 45%.

[0064] Table 2 Performance parameters of various metasurface units

[0065] As can be seen from the above, the metasurface antenna of the present invention can effectively achieve the characteristics of wide bandwidth, stable high gain, low profile, and miniaturization.

[0066] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A planar capacitively loaded metasurface antenna, characterized in that, The device includes a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate stacked sequentially from top to bottom; a power supply network is disposed at the bottom of the third dielectric substrate; a metal ground plane is disposed between the second and third dielectric substrates; coupling gaps are formed on the metal ground plane; and a metasurface structure composed of multiple metasurface units is disposed on the first dielectric substrate. The metasurface unit includes a metasurface patch; the metasurface patch is disposed on the upper surface of the first dielectric substrate; corresponding metal walls are disposed on both sides of the metasurface patch, the metal walls being along the antenna polarization direction; the metal walls are embedded in the first dielectric substrate, and the metal walls are in contact with the metasurface patch; Energy is input from the power supply network and coupled to the metasurface structure through the coupling gaps of the metal floor, which radiates the energy upwards in a directional manner. Multiple metal pillars are arranged side by side along the antenna polarization direction to form the metal wall; The plurality of metal pillars are embedded within the first dielectric substrate and in contact with the metasurface patch; the length of the metal wall... W 1 The range is [0.05]. λ 0,0.2 λ 0], λ 0 represents the free space wavelength; one or more metal walls are provided on both sides of the metasurface patch; when multiple metal walls are provided on both sides of the metasurface patch, the multiple metal walls on one side of the metasurface patch are arranged side by side.

2. The metasurface antenna based on planar capacitor loading according to claim 1, characterized in that, The multiple metasurface units on the first dielectric substrate are distributed in a rectangular array.

3. The metasurface antenna based on planar capacitor loading according to claim 2, characterized in that, The gap width between the metasurface units G 1 The range is [0.001]. λ 0,0.02 λ 0], λ 0 represents the wavelength in free space.

4. The metasurface antenna based on planar capacitor loading according to claim 1, characterized in that, The dielectric constant of the first dielectric substrate ranges from [2.2, 10.2], and the thickness h2 ranges from [0.001]. λ 0,0.05 λ 0]; The dielectric constant of the second dielectric substrate ranges from [2.2, 10.2], and the thickness h1 ranges from [0.001]. λ 0,0.05 λ 0]; The dielectric constant of the third dielectric substrate ranges from [2.2, 10.2], and the thickness h0 ranges from [0.001]. λ 0,0.1 λ 0]; λ 0 represents the wavelength in free space.

5. A metasurface antenna based on planar capacitor loading according to claim 1, characterized in that, The metal floor is square, and its side length is... GL The range is [0.3]. λ 0, λ 0]; A rectangular coupling slot is provided on the metal floor, the length of the coupling slot being 2× Lss The range is [0.1] λ g 0.8 λ g The width of the coupling gap Ws The range is [0.05]. λ g 0.5 λ g ],in λ g This is the effective wavelength of the dielectric substrate in the second layer.

6. A metasurface antenna based on planar capacitor loading according to claim 1, characterized in that, The power supply network is configured as a microstrip metal sheet, with a length ranging from [0.1...]. λ g1 0.8 λ g1 The width of the microstrip metal sheet ranges from [0.1]. λ g1 0.5 λ g1 ],in λ g1 This is the effective wavelength of the dielectric material in the third dielectric substrate.

7. A metasurface antenna based on planar capacitor loading according to claim 6, characterized in that, The power supply network is arranged perpendicularly to the coupling gap, and the coupling gap is arranged symmetrically with the center line of the power supply network as the axis.

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