A broadband omnidirectional metasurface antenna based on eigenmode analysis

Abstract

The present invention relates to a broadband omnidirectional metasurface antenna based on characteristic mode analysis, which mainly solves the technical problem that the existing broadband omnidirectional antenna has a narrow bandwidth. It includes a metasurface layer, a microstrip feeding patch layer and a connecting column; the metasurface layer includes a first dielectric substrate and a metasurface structure arranged on the upper surface of the first dielectric substrate; the microstrip feeding patch layer is arranged below the first dielectric substrate, and an air layer is arranged between the two, and they are connected by a connecting column; the metasurface structure includes a first patch, 4 second patches, 4 third patches and 4 groups of fourth patches; and the first patch and the second patch have the same size, and the sizes of the second patch, the third patch and the fourth patch decrease in sequence; the straight-line distances between the center points of the first patch and the adjacent second patch, the second patch and the adjacent third patch and the fourth patch, and the third patch and the adjacent fourth patch are all equal.

Description

Technical Field

[0001] The invention relates to an antenna, in particular to a broadband omnidirectional metasurface antenna based on characteristic mode analysis. Background Art

[0002] With the rapid development of mobile communication technology, broadband omnidirectional antennas are increasingly being used. Traditional monopole antennas, due to their narrow bandwidth and high profile, are no longer able to meet the application requirements of modern mobile communication systems.

[0003] At present, many scholars design broadband omnidirectional antennas with excellent performance based on characteristic mode analysis: In 2021, Li Zhi et al. designed a broadband metasurface antenna using characteristic mode analysis, Li Zhi, Ma Runbo and Han Liping, Design of broadband metasurface antenna based on characteristic mode analysis. Journal of Test Technology, 2021.35(06): pp. 539-543; The metasurface structure was designed by splitting the units located at the corners of the metasurface structure into 3×3 sub-arrays and the edge patches into 4×4 sub-arrays. The feeding method is slot coupling feeding. By merging the metasurface mode and the slot mode, an impedance bandwidth of 53.4% ​​was achieved. Han Guorui and others from Shanxi University designed a slot-coupled fed metasurface broadband omnidirectional antenna based on characteristic mode analysis. Han Guorui, Tian Kai and Pei Lili, Design of broadband omnidirectional antenna based on characteristic mode analysis. Journal of Test Technology, 2020.34(2): pp. 159-162, 168; The metasurface structure consists of 16 1 / 4 circles with a radius of r forming a 4×4 patch array. Four narrow slots are placed at the four corners of the metasurface structure. The feeding network adopts a one-to-four Wilkinson power divider to achieve good omnidirectional radiation characteristics. In 2020, Sihao Liu designed a circularly polarized metasurface omnidirectional antenna, Liu S, Yang D, Chen Y, ct al, Compatible integration of circularly polarized omnidirectional metasurface antenna with solar cells[J]. IEEE Transactions on Antennas and Propagation, 2019, 68(5): 4155-4160; four coupling slots are rotationally symmetrically distributed at the four corners of the metasurface structure, and a 1-to-4 feeding network provides a sequentially rotating 90° phase difference, thereby generating circular polarization, and finally obtaining omnidirectional circularly polarized radiation characteristics.

[0004] However, existing broadband omnidirectional antennas still have the problem of narrow bandwidth, and how to broaden the bandwidth of broadband omnidirectional antennas and obtain stable antenna performance is still full of challenges. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problem of narrow bandwidth of existing broadband omnidirectional antennas and to provide a broadband omnidirectional metasurface antenna based on characteristic mode analysis.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A broadband omnidirectional metasurface antenna based on characteristic mode analysis, which is special in that:

[0008] It includes a metasurface layer, a microstrip feeding patch layer and a connecting column;

[0009] The super surface layer includes a first dielectric substrate and a super surface structure arranged on the upper surface of the first dielectric substrate; the microstrip feeding patch layer is arranged below the first dielectric substrate, and an air layer is arranged between the two, and the two are connected by a connecting column;

[0010] The metasurface structure includes a first patch, four second patches, four third patches and four groups of fourth patches; the number of fourth patches in each group is three; the first patch, the second patch, the third patch and the fourth patch are all regular 2X-gons, or are all rectangles, or are all circles; and the first patch and the second patch have the same size, and the sizes of the second patch, the third patch and the fourth patch decrease in sequence; wherein X≥2;

[0011] The first patch, the four second patches, and the four third patches are arranged in a 3×3 array, and the first patch is arranged at the center of the first dielectric substrate, the four second patches are arranged rotationally symmetrically around the center of the first patch, and the rotation angle is 90°, and the four third patches are located between two adjacent second patches and are arranged rotationally symmetrically around the center of the first patch; if the first patch, the second patch, and the third patch are regular 2X-gons or rectangles, the corresponding sides of the first patch and the second patch are arranged correspondingly, and the corresponding sides of the second patch and the third patch are arranged correspondingly;

[0012] The four groups of fourth patches are arranged on the first dielectric substrate at positions outside the second patch and the third patch, and the center line of the three fourth patches in each group is parallel to the center line of the two third patches and one second patch close thereto; if the fourth patch is a regular 2X-gon or a rectangle, the corresponding sides of the fourth patch are arranged corresponding to the corresponding sides of the second patch and the third patch;

[0013] The straight-line distances between the center points of the first patch and the adjacent second patch, the straight-line distances between the second patch and the adjacent third and fourth patches, and the straight-line distances between the third patch and the adjacent fourth patch are all equal.

[0014] Furthermore, the first patch, the second patch, the third patch and the fourth patch are all regular 2X-gons, and X=2.

[0015] Furthermore, the first patch, the second patch, the third patch and the fourth patch are all regular 2X-gons, and X=3.

[0016] Furthermore, the side lengths of the first patch and the second patch are both 10.8 mm, the side length of the third patch is 8.9 mm, and the side length of the fourth patch is 5.2 mm;

[0017] The first dielectric substrate is a circular plate with a radius of 32 mm and a thickness of 1 mm.

[0018] Further, the microstrip feeding patch layer includes a second dielectric substrate, a floor, a coaxial probe and a feeding patch arranged at the center position of the upper side of the second dielectric substrate;

[0019] The upper side of the second dielectric substrate is connected to the lower side of the first dielectric substrate through a connecting column; the air layer refers to the space between the first dielectric substrate and the second dielectric substrate on one side close to each other;

[0020] The floor is arranged on the lower side of the second dielectric substrate; the feeding patch and the second dielectric substrate are both provided with metal vias at the center positions; the coaxial probe is installed in the metal vias of the feeding patch and the second dielectric substrate and connected to the floor.

[0021] Furthermore, the first dielectric substrate and the second dielectric substrate are both circular plates, and the diameters and dielectric constants of the two are the same, and the thickness of the first dielectric substrate is smaller than the thickness of the second dielectric substrate;

[0022] The feeding patch is a circular patch.

[0023] Furthermore, the thickness of the second dielectric substrate is 3 mm;

[0024] The dielectric constants of the first dielectric substrate and the second dielectric substrate are both 4.4, the radii are both 32 mm, and the spacing between them is 0.5 mm;

[0025] The radius of the feed patch is 14 mm and the radius of the floor is 32 mm.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The direction of the antenna of the present invention at each frequency point Figure 1 It has high consistency and good broadband omnidirectional characteristics; it also has a simple structure, wide bandwidth, high stability, and low manufacturing cost, and has broad application prospects.

[0028] 2. The present invention adopts capacitive coupling excitation, and the feeding structure adopts a microstrip circular patch for coaxial bottom feeding, and the feeding position is placed at the minimum current, that is, the center position of the second dielectric substrate, thereby further achieving the purpose of widening the antenna bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0030] Figure 2 is a schematic structural diagram of a super surface layer in an embodiment of the present invention;

[0031] Figure 3 is a schematic structural diagram of a microstrip feeding patch layer in an embodiment of the present invention;

[0032] Figure 4 It is a schematic diagram of the structure of the existing uniform super surface layer;

[0033] Figure 5 is the mode saliency map of the four characteristic modes of the existing uniform metasurface structure;

[0034] Figure 6 is a current distribution diagram of the existing uniform metasurface structure at the resonance point under the first characteristic mode;

[0035] Figure 7 is the directional diagram of the existing uniform metasurface structure at the resonance point under the first characteristic mode;

[0036] Figure 8 is the current distribution diagram of the existing uniform metasurface structure at the resonance point under the second characteristic mode;

[0037] Fig. 9 is the directional diagram of the existing uniform metasurface structure at the resonance point under the second characteristic mode;

[0038] Fig.10 is the current distribution diagram at the resonance point of the existing uniform metasurface structure under the third characteristic mode;

[0039] Fig.11 is the directional diagram of the existing uniform metasurface structure at the resonance point under the third characteristic mode;

[0040] Fig.12 is the current distribution diagram at the resonance point of the existing uniform metasurface structure under the fourth characteristic mode;

[0041] Fig.13 is the directional diagram of the existing uniform metasurface structure at the resonance point under the fourth characteristic mode;

[0042] Fig.14 This is the surface current distribution diagram of the existing uniform metasurface structure in the third characteristic mode and at a frequency band of 4.5 GHz;

[0043] Fig.15 It is the surface radiation pattern of the existing uniform metasurface structure in the third characteristic mode and the frequency band of 4.5 GHz;

[0044] Fig.16 This is the surface current distribution diagram of the existing uniform metasurface structure in the third characteristic mode and at a frequency band of 5 GHz;

[0045] Fig.17 It is the surface radiation pattern of the existing uniform metasurface structure in the third characteristic mode and the frequency band of 5 GHz;

[0046] Fig.18 This is the surface current distribution diagram of the existing uniform metasurface structure in the third characteristic mode and at a frequency band of 5.5 GHz;

[0047] Fig.19 It is the surface radiation pattern of the existing uniform metasurface structure in the third characteristic mode and the frequency band of 5.5 GHz;

[0048] Fig. 20 This is the surface current distribution diagram of the existing uniform metasurface structure in the third characteristic mode and at a frequency band of 6 GHz;

[0049] Fig.21 It is the surface radiation pattern of the existing uniform metasurface structure in the third characteristic mode and the frequency band of 6 GHz;

[0050] Fig. 22 This is the surface current distribution diagram of the existing uniform metasurface structure in the third characteristic mode and at a frequency band of 6.5 GHz;

[0051] Fig.23 It is the surface radiation pattern of the existing uniform metasurface structure in the third characteristic mode and the frequency band of 6.5 GHz;

[0052] Fig.24 This is the surface current distribution diagram of the existing uniform metasurface structure in the third characteristic mode and at a frequency band of 7 GHz;

[0053] Fig.25 It is the surface radiation pattern of the existing uniform metasurface structure in the third characteristic mode and the frequency band of 7 GHz;

[0054] Fig.26 This is the surface current distribution diagram of the existing uniform metasurface structure in the third characteristic mode and at a frequency band of 7.5 GHz;

[0055] Fig. 27 It is the surface radiation pattern of the existing uniform metasurface structure in the third characteristic mode and the frequency band of 7.5 GHz;

[0056] Fig.28 This is the surface current distribution diagram of the existing uniform metasurface structure in the third characteristic mode and at a frequency band of 8 GHz;

[0057] Fig.29It is the surface radiation pattern of the existing uniform metasurface structure in the third characteristic mode and the frequency band of 8.GHz;

[0058] Fig.30 This is the surface current distribution diagram of the existing uniform metasurface structure in the third characteristic mode and at a frequency band of 8.5 GHz;

[0059] Fig.31 It is the surface radiation pattern of the existing uniform metasurface structure in the third characteristic mode and the frequency band of 8.5 GHz;

[0060] Fig.32 It is a surface current distribution diagram of the super surface structure in the third characteristic mode in the embodiment of the present invention when the frequency band is 4.5 GHz;

[0061] Fig.33 is a surface radiation pattern of the supersurface structure in the implementation of the present invention in the third characteristic mode and at a frequency band of 4.5 GHz;

[0062] Fig.34 It is a surface current distribution diagram of the super surface structure in the third characteristic mode in the embodiment of the present invention when the frequency band is 5 GHz;

[0063] Fig.35 is a surface radiation pattern of the supersurface structure in the implementation of the present invention in the third characteristic mode and at a frequency band of 5 GHz;

[0064] Fig.36 It is a surface current distribution diagram of the super surface structure in the third characteristic mode in the embodiment of the present invention when the frequency band is 5.5 GHz;

[0065] Fig.37 is a surface radiation pattern of the supersurface structure in the implementation of the present invention in the third characteristic mode and at a frequency band of 5.5 GHz;

[0066] Fig.38 It is a surface current distribution diagram of the super surface structure in the third characteristic mode in the embodiment of the present invention when the frequency band is 6 GHz;

[0067] Fig.39 is a surface radiation pattern of the supersurface structure in the implementation of the present invention in the third characteristic mode and at a frequency band of 6 GHz;

[0068] Fig.40 It is a surface current distribution diagram of the super surface structure in the third characteristic mode in the embodiment of the present invention when the frequency band is 6.5 GHz;

[0069] Fig.41 is a surface radiation pattern of the supersurface structure in the implementation of the present invention in the third characteristic mode and at a frequency band of 6.5 GHz;

[0070] Fig.42It is a surface current distribution diagram of the super surface structure in the third characteristic mode in the embodiment of the present invention when the frequency band is 7 GHz;

[0071] Fig.43 is a surface radiation pattern of the supersurface structure in the implementation of the present invention in the third characteristic mode and at a frequency band of 7 GHz;

[0072] Fig.44 It is a surface current distribution diagram of the super surface structure in the third characteristic mode in the embodiment of the present invention when the frequency band is 7.5 GHz;

[0073] Fig.45 is a surface radiation pattern of the supersurface structure in the implementation of the present invention in the third characteristic mode and at a frequency band of 7.5 GHz;

[0074] Fig.46 It is a surface current distribution diagram of the super surface structure in the third characteristic mode in the embodiment of the present invention when the frequency band is 8 GHz;

[0075] Fig.47 is a surface radiation pattern of the supersurface structure in the implementation of the present invention in the third characteristic mode and at a frequency band of 8.GHz;

[0076] Fig.48 It is a surface current distribution diagram of the super surface structure in the third characteristic mode in the embodiment of the present invention when the frequency band is 8.5 GHz;

[0077] Fig.49 is a surface radiation pattern of the supersurface structure in the implementation of the present invention in the third characteristic mode and at a frequency band of 8.5 GHz;

[0078] Fig.50 is a comparison diagram of the pattern significance of the super surface structure in the embodiment of the present invention and the existing uniform super surface structure;

[0079] Fig.51 is a comparison diagram of the mode significance of the metasurface structure without and with the feeding patch in an embodiment of the present invention;

[0080] Fig.52 is a simulation result of the reflection coefficient of an embodiment of the present invention;

[0081] Fig.53 is a gain diagram simulation result of an embodiment of the present invention;

[0082] Fig.54 is a directional diagram of an embodiment of the present invention in the XOZ plane and at a frequency band of 5 GHz;

[0083] Fig.55 is a directional diagram of an embodiment of the present invention in the XOY plane and at a frequency band of 5 GHz;

[0084] Fig.56is a directional diagram of an embodiment of the present invention in the XOZ plane and at a frequency band of 6 GHz;

[0085] Fig.57 is a directional diagram of an embodiment of the present invention in an XOY plane at a frequency band of 6 GHz;

[0086] Fig.58 is a directional diagram of an embodiment of the present invention in the XOZ plane and at a frequency band of 7 GHz;

[0087] Fig.59 is a directional diagram of an embodiment of the present invention in the XOY plane and at a frequency band of 7 GHz;

[0088] Fig.60 is a directional diagram of an embodiment of the present invention in the XOZ plane and at a frequency band of 8 GHz;

[0089] Fig.61 It is the directional diagram of the embodiment of the present invention in the XOY plane and at a frequency band of 8 GHz.

[0090] In the figure:

[0091] 01-Square patch;

[0092] 1-super surface layer, 11-first dielectric substrate, 12-first patch, 13-second patch, 14-third patch, 15-fourth patch;

[0093] 2-microstrip feeding patch layer, 21-second dielectric substrate, 22-floor, 23-coaxial probe, 24-feeding patch;

[0094] 3-Connecting column, 4-Air layer. DETAILED DESCRIPTION

[0095] In order to make the purpose, advantages and features of the present invention clearer, the broadband omnidirectional metasurface antenna based on characteristic mode analysis proposed by the present invention is further described in detail below in combination with the accompanying drawings and specific embodiments. According to the following specific implementation methods, the advantages and features of the present invention will be clearer. It should be noted that: the drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention; secondly, the structure shown in the drawings is often part of the actual structure.

[0096] The present invention is further described in detail below in conjunction with a specific metasurface antenna structure design process to better demonstrate the advantages of the present invention:

[0097] The present invention adopts electromagnetic simulation software CST to perform characteristic mode analysis, and the operating frequency band of the metasurface antenna designed based on the characteristic mode analysis is 4.5GHz-8.5GHz.

[0098] like Figure 4As shown in FIG. 1 , the initial metasurface structure before design is a 5×5 uniform array composed of square patches 01, and all square patches 01 have the same size and period. CST is used to perform characteristic mode analysis on the uniform metasurface structure, and by designing the metasurface units to be of three different sizes and removing the outermost square patches 01, the present invention is obtained as shown in FIG. Figure 2 The non-uniform array metasurface structure shown is composed of 21 square units.

[0099] The design principle of the present invention is as follows: First, the 5×5 super surface structure before design is calculated (reference Figure 4 ) to obtain the mode significance curves of each characteristic mode and the mode current distribution and far-field pattern on the metasurface structure corresponding to each characteristic mode; secondly, analyze the mode current and pattern, select the characteristic mode with current distribution along the radial direction and omnidirectional radiation pattern as the dominant mode, and analyze the current distribution and pattern of the dominant mode at different frequencies; thirdly, according to the surface current distribution characteristics of the dominant mode, improve the metasurface patch unit, and adjust the surface current distribution by changing the unit size, so as to complete the design of the metasurface structure. Finally, analyze the current distribution on the designed metasurface structure, select the capacitive coupling excitation method, and set the feeding point position to the weakest current point.

[0100] Specific:

[0101] In the design process, CST is first used to perform characteristic mode analysis on the metasurface structure before design. Mode significance is one of the important indicators to measure the radiation potential of a mode. The frequency band with a mode significance value > 0.707 can be effectively radiated with electromagnetic waves. Figure 5 As shown in the figure, the four mode significance curves of the metasurface structure before the design of the present invention are shown. It can be seen that the mode significance curves of the first characteristic mode and the second characteristic mode overlap, and the mode significance value of the two characteristic modes is 1 at 4.55GHz, and resonance occurs; the mode significance value of the third characteristic mode is 1 at the resonance frequency of 5GHz, and the fourth characteristic mode resonates at a frequency of 4.7GHz. The mode bandwidth of the third characteristic mode is the widest, indicating that this characteristic mode can achieve the best effect of broadband design.

[0102] Figure 6-Figure 13The surface current distribution and directional pattern of the four characteristic modes of the metasurface structure before design of the present invention at their respective resonance points are given. The first characteristic mode and the second characteristic mode of the metasurface structure before design are an orthogonal mode pair, and the surface currents of the two are orthogonal to each other, and the current flows in the same direction. The maximum radiation direction of the directional pattern obtained after the far field superposition is along the axial direction. The surface currents corresponding to the third characteristic mode and the fourth characteristic mode flow in opposite directions, and the far fields cancel each other out. There is a zero dip in the axial direction of the directional pattern, and the maximum radiation direction is horizontally omnidirectional. Differently, the current of the third characteristic mode flows uniformly from the inside to the outside in the radial direction, and the directional pattern shows good omnidirectional characteristics, while the current of the fourth characteristic mode flows in opposite directions in the X and Y directions, which is a high-order mode and is more difficult to excite. Therefore, in order to design an omnidirectional radiating metasurface antenna, the third characteristic mode can be used as the dominant mode of the metasurface before design.

[0103] In order to design a broadband omnidirectional metasurface antenna, the mode current and far-field distribution of the dominant mode at different frequencies are analyzed. Figure 14-Figure 31 The dominant mode of the metasurface structure before design of the present invention, namely the surface current distribution and radiation pattern of the third characteristic mode at different frequency points are given. It can be seen that in the low-frequency band, the current distribution on the metasurface structure before design flows radially from the inside to the outside, the current in the outermost row is weak, and the current is mainly concentrated on the 3×3 units in the second outermost row, and the radiation pattern has good omnidirectional characteristics. However, as the frequency increases, at 6.5GHz, the current on the outermost row of units in the metasurface structure increases, and the current on these units flows from the inside to the outside, which is opposite to the current flow direction of the units at the edge of the second outermost row; at the same time, the unit current at the four corners of the second outermost row is weak, and the metasurface structure has multiple current zeros at these four positions, and its radiation pattern produces multiple radiation zeros accordingly.

[0104] according to Figure 14-Figure 31 The third characteristic mode surface current distribution characteristics shown in the figure, in order to suppress the current on the outermost row of units on the metasurface structure and improve the energy concentration, the outermost row of units in the metasurface structure are designed to be the smallest size, the units at the four corners of the second outer row are designed to be medium size, and the units at the edge of the second outer row are designed to be the largest size. For simplicity, the unit size at the edge of the second outer row is designed to be the same as the unit size of the uniform metasurface before design.

[0105] like Figure 32-Figure 49As shown, it is the surface current distribution and directional diagram of the third characteristic mode of the designed metasurface structure of the present invention at each frequency point. It can be seen that the current intensity on the outermost row unit in the designed metasurface structure is weakened, and the current is mainly concentrated on the four units at the edge of the sub-outer row. The current flows from the inside to the outside along the X and Y axis directions, respectively, and the directional diagram shows good omnidirectional characteristics. The surface current of the designed metasurface structure contains only one current zero point. When the frequency is 8GHz, the current of the units at the four corners of the sub-outer row is enhanced, and the current flows from the outside to the inside along the diagonal direction. The directional diagram shows a certain split, the horizontal plane shows a certain fluctuation, and the horizontal roundness decreases. However, within a wider frequency band, the current distribution on the designed metasurface structure is similar, and the direction Figure 1 Therefore, the bandwidth can be effectively widened by superimposing different resonance points.

[0106] like Fig.50 As shown in FIG. 1 , it is a comparison diagram of the mode significance of the structure of the metasurface before and after the design of the present invention. It can be seen that the mode significance curve of the dominant mode of the improved metasurface structure moves to high frequency, and the bandwidth of the mode significance value>0.707 is widened, indicating that the improved metasurface can widen the bandwidth.

[0107] In order to effectively excite the main mode of the designed metasurface, according to the characteristic mode theory, the capacitive coupling excitation method is adopted, and the feeding point of the circular feeding patch should be placed at the weakest point of the mode surface current, that is, the center of the metasurface.

[0108] Fig.51 The figure shows a comparison of the mode significance curves of the metasurface structure loaded with and without the feeding patch after the design of the present invention. It can be seen that the mode bandwidth of the metasurface structure loaded with the feeding patch after the design is significantly greater than the mode bandwidth of the metasurface structure alone, which shows that the merging of the metasurface mode and the microstrip circular patch mode can achieve the purpose of the dual-mode broadband metasurface antenna.

[0109] In order to verify the performance of the designed metasurface antenna, the final designed broadband omnidirectional antenna based on the metasurface structure was simulated to obtain the reflection coefficient, gain and radiation pattern, as shown in Fig.52 and 53 As shown in the figure. The frequency band where the antenna's reflection coefficient is less than -10dB is 4.57GHz-8.43GHz, and the relative bandwidth is 59.4%. In the entire working frequency band, the average gain is about 4.9dBi. Figure 54-61As shown in the figure, the directional pattern of the designed super-plane structure in the xoz plane (xoz plane is the vertical plane) is conical, and the directional pattern in the xoy plane (xoy is the horizontal plane) is a circle, similar to a vertical monopole antenna. Due to the influence of high-order modes, the horizontal directional pattern fluctuates to a certain extent at high frequencies. Even so, these directional patterns have good consistency throughout the frequency band, indicating that the designed broadband omnidirectional antenna based on the metasurface structure has good broadband omnidirectional characteristics.

[0110] Based on the above design principles and design process, a broadband omnidirectional metasurface antenna based on characteristic mode analysis in this embodiment is described in detail below. Figure 1-3 , including a metasurface layer 1, a microstrip feeding patch layer 2 and a plurality of connecting columns 3; the metasurface layer 1 includes a first dielectric substrate 11 and a metasurface structure arranged on the upper side of the first dielectric substrate 11; the microstrip feeding patch layer 2 includes a second dielectric substrate 21, a floor 22, a coaxial probe 23 and a feeding patch 24 arranged at the center position of the upper side of the second dielectric substrate 21; the upper side of the second dielectric substrate 21 is connected to the lower side of the first dielectric substrate 11 through a plurality of connecting columns 3, and the connecting columns 3 are located at the edge positions of the end faces of the first dielectric substrate 11 and the second dielectric substrate 21; a spacing is arranged on one side where the first dielectric substrate 11 and the second dielectric substrate 21 are close to each other, and the space of the spacing is the arranged air layer 4; the floor 22 is arranged in contact with the lower side of the second dielectric substrate 21; metal vias are arranged at the center positions of the feeding patch 24 and the second dielectric substrate 21, and the coaxial probe 23 is installed in the metal vias of the feeding patch 24 and the second dielectric substrate 21, and connected to the floor 22.

[0111] The metasurface structure includes a first patch 12, four second patches 13, four third patches 14 and four groups of fourth patches 15; the number of each group of fourth patches 15 is 3; the first patch 12, the second patch 13, the third patch 14 and the fourth patch 15 are all regular 2X-gons; and the first patch 12 and the second patch 13 have the same size, and the sizes of the second patch 13, the third patch 14 and the fourth patch 15 decrease successively; wherein X≥2; the first patch 12, the four second patches 13 and the four third patches 14 are arranged in a 3×3 array, and the first patch 12 is arranged at the center of the first dielectric substrate 11, the four second patches 13 are arranged rotationally symmetrically around the center of the first patch 12, and the rotation angle is 90°, and the four third patches 14 are located between two adjacent second patches 13 and are arranged rotationally symmetrically around the center of the first patch 12; the corresponding sides of the first patch 12 and the second patch 13 are opposite to each other. It should be arranged that the corresponding sides of the second patch 13 and the third patch 14 are arranged correspondingly; 4 groups of fourth patches 15 are arranged on the first dielectric substrate 11 at positions outside the second patch 13 and the third patch 14, and the center line of the three fourth patches 15 in each group is parallel to the center line of the two third patches 14 and one second patch 13 close to it; if the fourth patch 15 is a regular 2X polygon or a rectangle, the corresponding sides of the fourth patch 15 are arranged correspondingly to the corresponding sides of the second patch 13 and the third patch 14; the straight-line distances between the center points of the first patch 12 and the adjacent second patch 13, the second patch 13 and the adjacent third patch 14 and the fourth patch 15, and the third patch 14 and the adjacent fourth patch 15 are all equal; in other embodiments of the present invention, the straight-line distance between the center of the second patch 13 and the adjacent third patch 14 can also be appropriately increased and adjusted, which can further help adjust the matching and expand the bandwidth.

[0112] Specifically, in this embodiment, refer to Figure 2 , the first patch 12, the second patch 13, the third patch 14 and the fourth patch 15 are all set to be squares, then the four second patches 13 are respectively set at the four sides of the first patch 12, and the sides of the second patch 13 are set correspondingly to the sides of the first patch, and the center of the second patch 13 is on the same straight line as the center of the first patch; the four third patches are respectively set on the lines whose centers are the four corners of the first patch, and the sides of the third patches are set correspondingly to the sides of the second patches adjacent to them;

[0113] The first dielectric substrate 11 and the second dielectric substrate 21 are both circular plates, and the diameter and dielectric constant of the two are the same. The thickness of the first dielectric substrate 11 is less than the thickness of the second dielectric substrate 21; the feed patch 24 is a circular plate. Specifically, in this embodiment, the thickness of the second dielectric substrate 21 is designed to be 3mm; the dielectric constants of the first dielectric substrate 11 and the second dielectric substrate 21 are both 4.4, the radius is 32mm, and the spacing between the two is 0.5mm; the radius of the feed patch 24 is 14mm, and the radius of the floor 22 is 32mm. The side lengths of the first patch 12 and the second patch 13 are the same, both 10.8mm, the side lengths of the third patch 14 are 8.9mm, and the side lengths of the fourth patch 15 are 5.2mm; the first dielectric substrate 11 is a circular plate, with a radius of 32mm and a thickness of 1mm. Of course, the above parameters are all specific structural parameters designed by the present invention. In other embodiments of the present invention, the above structure can also be designed as other parameters according to specific volume requirements.

[0114] In a preferred embodiment of the present invention, the first patch 12, the second patch 13, the third patch 14 and the fourth patch 15 can all be circular plates, the first patch 12 and the second patch 13 have the same diameter, and the diameters of the second patch 13, the third patch 14 and the fourth patch 15 decrease successively.

[0115] In other embodiments of the present invention, the first patch 12, the second patch 13, the third patch 14 and the fourth patch 15 can all be rectangular plates. However, since the length and width of the rectangular blocks are not equal, the radiation field cannot be completely offset, causing the radiation pattern to be slightly distorted, and the positions of various frequency points cannot be completely consistent, which will slightly reduce the performance of the antenna.

[0116] It should be noted that the above-described specific implementations can enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way. All technical solutions and improvements that do not depart from the spirit and scope of the invention are included in the protection scope of the invention.

Claims

1. A broadband omnidirectional metasurface antenna based on characteristic mode analysis, characterized in that: It comprises a super surface layer (1), a microstrip feeding patch layer (2) and a connecting column (3); The supersurface layer (1) comprises a first dielectric substrate (11) and a supersurface structure arranged on the upper surface of the first dielectric substrate (11); the microstrip feeding patch layer (2) is arranged below the first dielectric substrate (11), and an air layer (4) is provided between the two, and the two are connected via a connecting column (3); The metasurface structure comprises a first patch (12), four second patches (13), four third patches (14) and four groups of fourth patches (15); the number of fourth patches (15) in each group is three; the first patch (12), the second patch (13), the third patch (14) and the fourth patch (15) are all regular 2X-gons, or are all rectangles, or are all circles; and the first patch (12) and the second patch (13) have the same size, and the sizes of the second patch (13), the third patch (14) and the fourth patch (15) decrease in sequence; wherein X≥2; The first patch (12), four second patches (13), and four third patches (14) are arranged in a 3×3 array, and the first patch (12) is arranged at the center of the first dielectric substrate (11), the four second patches (13) are arranged rotationally symmetrically around the center of the first patch (12), and the rotation angle is 90°, and the four third patches (14) are located between two adjacent second patches (13) and are arranged rotationally symmetrically around the center of the first patch (12); if the first patch (12), the second patch (13), and the third patch (14) are regular 2X-gons or rectangles, then the corresponding sides of the first patch (12) and the second patch (13) are arranged correspondingly, and the corresponding sides of the second patch (13) and the third patch (14) are arranged correspondingly; Four groups of the fourth patches (15) are arranged on the first dielectric substrate (11) at positions outside the second patches (13) and the third patches (14), and a center line connecting the three fourth patches (15) in each group is parallel to a center line connecting the two third patches (14) and one second patch (13) adjacent thereto; if the fourth patch (15) is a regular 2X-gon or a rectangle, corresponding sides of the fourth patch (15) are arranged corresponding to corresponding sides of the second patch (13) and the third patch (14); The straight-line distances between the center points of the first patch (12) and the adjacent second patch (13), the second patch (13) and the adjacent third patch (14) and fourth patch (15), and the third patch (14) and the adjacent fourth patch (15) are all equal.

2. The broadband omnidirectional metasurface antenna based on characteristic mode analysis according to claim 1, characterized in that: The first patch (12), the second patch (13), the third patch (14) and the fourth patch (15) are all regular 2X-gons, and X=2.

3. The broadband omnidirectional metasurface antenna based on characteristic mode analysis according to claim 1, characterized in that: The first patch (12), the second patch (13), the third patch (14) and the fourth patch (15) are all regular 2X-gons, and X=3.

4. The broadband omnidirectional metasurface antenna based on characteristic mode analysis according to claim 2, characterized in that: The side lengths of the first patch (12) and the second patch (13) are both 10.8 mm, the side length of the third patch (14) is 8.9 mm, and the side length of the fourth patch (15) is 5.2 mm; The first dielectric substrate (11) is a circular plate with a radius of 32 mm and a thickness of 1 mm.

5. A broadband omnidirectional metasurface antenna based on characteristic mode analysis according to any one of claims 1 to 4, characterized in that: The microstrip feeding patch layer (2) comprises a second dielectric substrate (21), a floor (22), a coaxial probe (23), and a feeding patch (24) arranged at the center position of the upper side of the second dielectric substrate (21); The upper side of the second dielectric substrate (21) is connected to the lower side of the first dielectric substrate (11) via a connecting column (3); the air layer (4) refers to the space between the first dielectric substrate (11) and the second dielectric substrate (21) on one side close to each other; The floor (22) is arranged in close contact with the lower side of the second dielectric substrate (21); metal vias are arranged at the center positions of the feeding patch (24) and the second dielectric substrate (21); the coaxial probe (23) is installed in the metal vias of the feeding patch (24) and the second dielectric substrate (21) and is connected to the floor (22).

6. The broadband omnidirectional metasurface antenna based on characteristic mode analysis according to claim 5, characterized in that: The first dielectric substrate (11) and the second dielectric substrate (21) are both circular plates, and both have the same diameter and dielectric constant, and the thickness of the first dielectric substrate (11) is smaller than the thickness of the second dielectric substrate (21); The feeding patch (24) is a circular patch.

7. The broadband omnidirectional metasurface antenna based on characteristic mode analysis according to claim 6, characterized in that: The thickness of the second dielectric substrate (21) is 3 mm; The dielectric constants of the first dielectric substrate (11) and the second dielectric substrate (21) are both 4.4, the radii are both 32 mm, and the distance between them is 0.5 mm; The radius of the feeding patch (24) is 14 mm, and the radius of the floor (22) is 32 mm.

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