Compact broadband circularly polarized non-uniform metasurface antenna

Abstract

The utility model discloses a compact broadband circularly polarized non-uniform metasurface antenna, which comprises a first dielectric substrate, a grounding plate and a second dielectric substrate, the first dielectric substrate, the grounding plate and the second dielectric substrate are sequentially attached from top to bottom; a plurality of elliptical metal patches are arranged on the upper surface of the first dielectric substrate; an L-shaped gap is etched in the grounding plate; a microstrip feed structure is arranged on the lower surface of the second dielectric substrate and comprises a microstrip line, a U-shaped feed branch knot and an SMA connector; one end of the microstrip line is connected with the U-shaped feed branch, and the other end is connected with the SMA connector; the microstrip line and the L-shaped slot are coupled to excite radiation of the metasurface structure. According to the utility model, the non-uniform elliptical metal patches are adopted to form the metasurface structure, the L-shaped gaps are adopted to realize coupled feeding, the metasurface structure generates resonance at multiple frequencies and has relatively wide impedance bandwidth and circularly polarized bandwidth, and the four rectangular metal patches in central symmetry are added around the metasurface structure, so that the circularly polarized bandwidth is further expanded.

Description

TECHNICAL FIELD

[0001] The utility model belongs to microwave antenna technical field, concretely relates to a compact broadband circularly polarized non-uniform metasurface antenna. BACKGROUND

[0002] Circularly polarized antennas can receive electromagnetic waves of any polarization and effectively reduce multipath interference in signal transmission, so they are widely used in satellite communication, navigation and positioning, and radio frequency identification systems. With the increasing integration of communication equipment, higher requirements are placed on the performance and size of antennas. As a new type of two-dimensional metamaterial structure, metasurfaces have the advantages of low profile, high gain, and easy processing. Through a special feeding method, metasurfaces can achieve circularly polarized radiation, thereby designing broadband circularly polarized antennas.

[0003] In recent years, domestic and foreign scholars have conducted a lot of research on broadband circularly polarized metasurface antennas and designed some broadband circularly polarized metasurface antennas. Simone Genovesi et al. published the article "Characteristic Modes Analysis of a Near-Field Polarization-Conversion Metasurface for the Design of a Wideband Circularly Polarized X-Band Antenna", which uses a 4x4 ring-shaped metal patch unit to form a metasurface as the antenna's radiation structure. The antenna achieves a maximum gain of 8.6dBic and a 3dB axial ratio bandwidth of 14.7%, with a size of 1.3λ0x1.3λ0(λ0 is the wavelength corresponding to the center frequency of the antenna's operating frequency band). In 2023, Ahmed El Yousf et al. published the article "A Broadband Circularly Polarized Single-Layer Metasurface Antenna Using Characteristic-Mode Analysis", which uses a coplanar waveguide feeding method to excite a metasurface structure composed of 4x4 rectangular metal patches. The metasurface antenna achieves a maximum gain of 8dBic and a 3dB axial ratio bandwidth of 19.42%, with a size of 1λ0x1λ0. However, these two metasurface antennas have a large size, which is not conducive to the integration of broadband communication systems, and the circularly polarized bandwidth is narrow, which is not conducive to the application of broadband communication systems. UTILITY MODEL CONTENT

[0004] The main purpose of the utility model is to overcome the shortcomings and deficiencies of the prior art and provide a compact broadband circularly polarized non-uniform metasurface antenna.

[0005] In order to achieve the above object, the utility model adopts the following technical scheme:

[0006] A compact broadband circularly polarized non-uniform metasurface antenna, comprising a first dielectric substrate, a ground plate and a second dielectric substrate;

[0007] The first dielectric substrate, the ground plate and the second dielectric substrate are sequentially attached from top to bottom;

[0008] The upper surface of the first dielectric substrate is provided with a plurality of elliptical metal patches, forming a metasurface structure;

[0009] The ground plate is etched with an L-shaped slot;

[0010] The lower surface of the second dielectric substrate is provided with a microstrip feed structure, including a microstrip line, a U-shaped feed branch and an SMA connector; one end of the microstrip line is connected to the U-shaped feed branch, and the other end is connected to the SMA connector; the microstrip line and the L-shaped slot are coupled to excite the metasurface structure to radiate.

[0011] Further, the elliptical metal patches are specifically 16, arranged in 4x4 on the upper surface of the first dielectric substrate;

[0012] The elliptical metal patches are divided into four types, specifically three types of elliptical metal patches with different size circular grooves cut in the center of the patches and an elliptical metal patch without a circular groove cut.

[0013] Further, the upper surface of the first dielectric substrate is also provided with a rectangular metal patch;

[0014] The number of rectangular metal patches is four, and the four rectangular patches are symmetrically arranged around the center of the metasurface structure on the upper surface of the first dielectric substrate.

[0015] Further, it also includes a metal column;

[0016] The lower surface of the second dielectric substrate is also symmetrically provided with two metal rectangular pads for welding the SMA connector; the metal column penetrates the second dielectric substrate and connects the rectangular pads and the ground plate respectively.

[0017] Further, it also includes a screw, which penetrates the first dielectric substrate, the ground plate and the second dielectric substrate, and the first dielectric substrate, the ground plate and the second dielectric substrate are tightly attached and fixed by the screw;

[0018] The screw is specifically a nylon PA66 screw, and the number is four.

[0019] Preferably, the length and width dimensions of the first dielectric substrate, the ground plate and the second dielectric substrate are the same, which are 46mmx46mm;

[0020] The first dielectric substrate and the second dielectric substrate are FR4 plates, the relative dielectric constant is 4.6, and the loss tangent value is 0.017; the thickness of the first dielectric substrate is 3 mm, and the thickness of the second dielectric substrate is 1 mm.

[0021] The ground plate is specifically a metal ground plate.

[0022] Preferably, the long axes of the elliptical metal patches are all 10 mm, and the short axes are all 8.5 mm.

[0023] The three kinds of elliptical metal patches with different sizes of circular grooves cut in the center of the patch, and the diameters of the circular grooves cut are 2 mm, 4 mm and 6 mm respectively.

[0024] Preferably, the sizes of the rectangular metal patches are all 1.5 mm*21 mm.

[0025] Preferably, the lengths of the L-shaped slots are 8.5 mm and 20.2 mm respectively, and the widths are both 2.8 mm.

[0026] Preferably, the width of the microstrip line is specifically 1.2 mm, and the length is 22.7 mm.

[0027] The length of the first section of the microstrip line of the U-shaped feed branch is 8 mm, and the width is 3.15 mm; the width of the second section of the microstrip line is 1.85 mm, and the length is 4.95 mm.

[0028] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0029] 1. The utility model adopts non-uniform elliptical metal patches to form a metasurface structure, because elliptical metal patches of different structures resonate at different frequencies, so a larger impedance bandwidth can be obtained; at the same time, through the L-shaped slot, the metasurface structure formed by the non-uniform elliptical metal patches is excited to produce circularly polarized radiation, and multiple circularly polarized radiation modes can be obtained, so the circularly polarized bandwidth is large and good impedance matching is maintained.

[0030] 2. The utility model adds four rectangular metal patches which are centrally symmetric around the metasurface structure as parasitic units without increasing the size of the antenna, which further widens the circularly polarized bandwidth.

[0031] 3. The antenna also has the advantages of wide frequency band, small size, high gain, simple installation steps, low material cost and the like, and has broad application potential in ultra-wideband positioning systems, satellite communication and radar systems. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is the overall structure schematic diagram of the utility model;

[0033] Figure 2 is a side view of the utility model;

[0034] Figure 3 is a first medium substrate upper surface schematic view in the utility model;

[0035] Figure 4 is the schematic diagram of the ground plate in the utility model;

[0036] Figure 5 is the schematic diagram of the second medium substrate lower surface in the utility model;

[0037] Figure 6 is the reflection coefficient curve of the embodiment antenna;

[0038] Figure 7 is the axial ratio curve of the embodiment antenna;

[0039] Figure 8 is the gain and efficiency curve of the embodiment antenna;

[0040] Figure 9a is the XOZ plane radiation pattern of the embodiment antenna at 4.8GHz;

[0041] Figure 9b is the YOZ plane radiation pattern of the embodiment antenna at 4.8GHz;

[0042] Figure 10a is the XOZ plane radiation pattern of the embodiment antenna at 5.5GHz;

[0043] Figure 10b is the YOZ plane radiation pattern of the embodiment antenna at 5.5GHz;

[0044] Figure 11a is the XOZ plane radiation pattern of the embodiment antenna at 6.2GHz;

[0045] Figure 11b is the YOZ plane radiation pattern of the embodiment antenna at 6.2GHz;

[0046] BRIEF DESCRIPTION OF DRAWINGS: 1- first medium substrate;2- second medium substrate;3- ground plate;4- screw;5- oval metal patch;6- rectangular metal patch;7- metal column;8- L-shaped slot;9- microstrip line;10- U-shaped feed branch;11- rectangular pad;12- SMA connector. DETAILED DESCRIPTION

[0047] The utility model will be described further in detail below in combination with embodiments and drawings, but the implementation mode of the utility model is not limited to this.

[0048] EMBODIMENT

[0049] As Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 indicated, the utility model relates to a compact broadband circularly polarized non-uniform metasurface antenna, including first dielectric substrate 1, ground plate 3 and second dielectric substrate 2;

[0050] First dielectric substrate, ground plate, second dielectric substrate are sequentially closely attached from top to bottom;

[0051] The upper surface of first dielectric substrate is equipped with a plurality of elliptical metal patches 5, and constitutes metasurface structure;Through special excitation, metasurface structure can produce circularly polarized radiation;

[0052] The ground plate is etched with L-shaped slot 8;The ground plate is used as the metal radiation plate of the metasurface antenna on one hand, and is coupled to the metasurface structure for feeding on the other hand through the L-shaped slot.

[0053] The lower surface of second dielectric substrate is equipped with microstrip feed structure, including microstrip line 9, U-shaped feed branch 10 and SMA connector 12;One end of the microstrip line is connected to the U-shaped feed branch, and the other end is connected to the SMA connector;The microstrip line and the L-shaped slot are coupled to excite the metasurface structure to radiate.

[0054] In the embodiment, the signal is input from the microstrip line on the lower surface of the second dielectric substrate into the U-shaped feed branch, is transmitted to the antenna radiation structure on the upper surface of the first dielectric substrate through the L-shaped slot on the ground plate, the metasurface structure in the antenna radiation structure generates equal-amplitude orthogonal polarized waves, and finally the energy is radiated out through the metasurface structure, so that a circularly polarized antenna is formed.

[0055] In the embodiment, the energy radiated by the metasurface is obtained through the L-shaped slot coupled by the microstrip feed structure on the lower surface of the second dielectric substrate, so that after the center frequency is determined, the circularly polarized bandwidth is optimized by adjusting the L-shaped slot, and the impedance matching bandwidth is optimized by adjusting the length and width of the U-shaped feed branch.

[0056] As Figure 3 indicated, in the embodiment, the elliptical metal patch is specifically 16, and is arranged on the upper surface of the first dielectric substrate in 4x4 arrangement;The elliptical metal patch is divided into four kinds, specifically three kinds of elliptical metal patches with different sizes of circular grooves cut in the center of the patch and elliptical metal patches without circular grooves cut.

[0057] In actual implementation, the circularly polarized radiation performance of the metasurface antenna can be improved by adjusting the ratio of the long axis and the short axis of the elliptical metal patch and the length and the width of the L-shaped slot. In this embodiment, the long axis of the elliptical metal patch is 10 mm, and the short axis is 8.5 mm; three elliptical metal patches with different sizes of circular grooves are cut in the center of the patch; the diameter of the circular groove is 2 mm, 4 mm and 6 mm respectively.

[0058] As shown in Figure 3 , in this embodiment, the upper surface of the first dielectric substrate is also provided with a rectangular metal patch 6; the number of the rectangular metal patch is 4, and the four rectangular patches are symmetrically arranged around the center of the metasurface structure on the periphery of the upper surface of the first dielectric substrate, which serves as a parasitic unit to further broaden the circularly polarized bandwidth. In actual implementation, the circularly polarized bandwidth can be further widened by adjusting the size of the rectangular metal patch; in this embodiment, the size of the rectangular metal patch is 1.5 mm x 21 mm.

[0059] As shown in Figure 2 and Figure 5 , in this embodiment, the lower surface of the second dielectric substrate is also symmetrically provided with two metal rectangular pads 11 for welding SMA connectors; this embodiment also includes a metal column 7 which penetrates the second dielectric substrate and connects the rectangular pad and the ground plate respectively.

[0060] As shown in Figure 1 , in this embodiment, it also includes a screw 4 which penetrates the first dielectric substrate, the ground plate and the second dielectric substrate, and the first dielectric substrate, the ground plate and the second dielectric substrate are tightly adhered and fixed by the screw; the screw is a nylon PA66 screw, and the number is 4.

[0061] In this embodiment, the length and width of the first dielectric substrate, the ground plate and the second dielectric substrate are the same, which is 46 mm x 46 mm; the first dielectric substrate and the second dielectric substrate are FR4 plates, and the relative dielectric constant is 4.6 and the loss tangent is 0.017; the thickness of the first dielectric substrate is 3 mm, and the thickness of the second dielectric substrate is 1 mm; the ground plate is a metal ground plate. The length of the L-shaped slot is 8.5 mm and 20.2 mm respectively, and the width is 2.8 mm. The width of the microstrip line is 1.2 mm, and the length is 22.7 mm; the length of the first section of the U-shaped feed branch is 8 mm, and the width is 3.15 mm; the width of the second section of the microstrip line is 1.85 mm, and the length is 4.95 mm.

[0062] As shown in Figure 6 and Figure 7As shown in the figure, the reflection coefficient curve and the axial ratio curve of the compact broadband circularly polarized non-uniform metasurface antenna of the embodiment are shown, and the antenna has a wide impedance bandwidth and a circular polarization bandwidth. The tested impedance bandwidth can reach 50.7% (4.37-7.34 GHz), the 3dB axial ratio bandwidth is 35.3% (4.55-6.5 GHz), and the overlapping bandwidth of the impedance and the axial ratio is 35.3% (4.55-6.5 GHz). As shown in the figure Figure 8 As shown in the figure, the gain and efficiency curves of the antenna of the embodiment are shown. As can be seen from the figure, the tested gain and efficiency are relatively stable within the axial ratio bandwidth, and the highest gain reaches 7.1dBic.

[0063] As shown in the figure Figure 9a and Figure 9b As shown in the figure, the radiation patterns of the compact broadband circularly polarized non-uniform metasurface antenna of the embodiment in the XOZ and YOZ planes at 4.8GHz are shown; as shown in the figure Figure 10a and Figure 10b As shown in the figure, the radiation patterns of the antenna of the embodiment in the XOZ and YOZ planes at 5.5GHz are shown; as shown in the figure Figure 11a and Figure 11b As shown in the figure, the radiation patterns of the antenna of the embodiment in the XOZ and YOZ planes at 6.2GHz are shown; as can be seen from the figure, the radiation pattern of the antenna of the embodiment is in a directional radiation mode, and radiates along the Z-axis direction. The back lobe of the radiation pattern is relatively small, and has a good front-to-back ratio.

[0064] In the embodiment, a compact broadband circularly polarized non-uniform metasurface antenna is made of two layers of dielectric substrates. The metasurface structure is composed of 4x4 arranged non-uniform elliptical metal patches, wherein different elliptical metal patches resonate at different frequencies. An L-shaped slot structure is used for coupling and feeding to excite the metasurface structure to generate circularly polarized radiation, thereby obtaining a larger circular polarization bandwidth and impedance bandwidth. Four centrally symmetric rectangular metal patches are added around the metasurface as parasitic units to further widen the circular polarization bandwidth. In addition, the antenna of the embodiment has the characteristics of small size, large circular polarization bandwidth, simple installation steps, and low material cost.

[0065] It should be further noted that in the present specification, terms such as "comprise", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "comprises a" does not exclude the presence of another identical element in the process, method, article or device comprising the element.

[0066] The above description of disclosed embodiments enables one of ordinary skill in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A compact broadband circularly polarized non-uniform metasurface antenna, characterized in that, The first dielectric substrate, the ground plate and the second dielectric substrate are sequentially attached from top to bottom. The upper surface of the first dielectric substrate is provided with a plurality of elliptical metal patches to form a metasurface structure. The ground plate is etched with an L-shaped slot. The lower surface of the second dielectric substrate is provided with a microstrip feed structure including a microstrip line, a U-shaped feed branch and an SMA connector. One end of the microstrip line is connected to the U-shaped feed branch, and the other end is connected to the SMA connector. The microstrip line and the L-shaped slot are coupled to excite the metasurface structure to radiate. The elliptical metal patches are specifically 16, arranged in 4x4 on the upper surface of the first dielectric substrate.

2. The compact wideband circularly polarized non-uniform metasurface antenna according to claim 1, wherein, The elliptical metal patches are divided into four types, specifically three types of elliptical metal patches with different sizes of circular grooves cut in the center of the patches and one elliptical metal patch without a circular groove. The upper surface of the first dielectric substrate is also provided with a rectangular metal patch.

3. The compact wideband circularly polarized non-uniform metasurface antenna according to claim 1, wherein, The number of rectangular metal patches is four, and the four rectangular patches are symmetrically arranged around the center of the metasurface structure on the upper surface of the first dielectric substrate. It also includes a metal column.

4. The compact wideband circularly polarized non-uniform metasurface antenna according to claim 1, wherein, The lower surface of the second dielectric substrate is also symmetrically provided with two metal rectangular pads for welding the SMA connector; the metal column penetrates the second dielectric substrate and connects the rectangular pad and the ground plate respectively. It also includes a screw that penetrates the first dielectric substrate, the ground plate and the second dielectric substrate, and the first dielectric substrate, the ground plate and the second dielectric substrate are tightly attached and fixed by the screw.

5. The compact wideband circularly polarized non-uniform metasurface antenna according to claim 1, wherein, The screw is specifically a nylon PA66 screw, and the number is four. The length and width of the first dielectric substrate, the ground plate and the second dielectric substrate are the same, which is 46mmx46mm.

6. The compact wideband circularly polarized non-uniform metasurface antenna according to claim 1, wherein, The first dielectric substrate and the second dielectric substrate are FR4 plates with a relative dielectric constant of 4.6 and a loss tangent of 0.017; the thickness of the first dielectric substrate is 3mm, and the thickness of the second dielectric substrate is 1mm. The ground plate is specifically a metal ground plate. The major axis of the elliptical metal patch is 10mm, and the minor axis is 8.5mm.

7. The compact wideband circularly polarized non-uniform metasurface antenna according to claim 1, wherein, The three types of elliptical metal patches with different sizes of circular grooves cut in the center of the patches have diameters of 2mm, 4mm and 6mm respectively. The size of the rectangular metal patch is 1.5mmx21mm.

8. The compact wideband circularly polarized non-uniform metasurface antenna according to claim 1, wherein, The length of the L-shaped slot is 8.5mm and 20.2mm respectively, and the width is 2.8mm.

9. The compact wideband circularly polarized non-uniform metasurface antenna according to claim 1, wherein, The width of the microstrip line is specifically 1.2mm, and the length is 22.7mm.

10. The compact wideband circularly polarized non-uniform metasurface antenna of claim 1, wherein, The first section of the U-shaped feed branch has a microstrip line length of 8mm and a width of 3.15mm, and the second section has a microstrip line width of 1.85mm and a length of 4.95mm. ​

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