Broadband high-gain antenna based on double-frequency near-zero metamaterial

Abstract

The invention discloses a broadband high-gain antenna based on a double-frequency near-zero metamaterial. The broadband high-gain antenna comprises at least one broadband patch antenna and a double-frequency-band zero-refractive-index metamaterial coating located above the broadband patch antenna. The dual-frequency-band zero-refractive-index metamaterial covering layer is composed of multiple layers of periodically-arranged dual-frequency zero-refractive-index metamaterial units, each dual-frequency zero-refractive-index metamaterial unit is composed of a substrate and a metal pattern printed on the substrate, and the metal patterns on the front face and the back face of the substrate form a complementary dual-layer symmetrical resonance ring structure. The invention also discloses a design method of the antenna, and the antenna can achieve the high-gain antenna design on multiple frequency bands, and is suitable for the rapid development and changeable application scenarios of the modern communication technology.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology, and in particular relates to a broadband high-gain antenna based on dual-frequency near-zero metamaterials. The antenna is suitable for multiple fields such as satellite communications, radar, radio direction finding, and aviation communications, and can effectively improve signal transmission efficiency and accuracy. Background Art

[0002] In wireless communications, high-gain antennas can significantly improve the efficiency and accuracy of signal transmission, and demonstrate important value in many fields such as mobile communications, satellite communications, radar detection, the Internet of Things, and radio and television.

[0003] Zero-index metasurfaces (ZIM) are artificial material surfaces with special electromagnetic properties, whose refractive index is close to zero or zero. Unlike conventional materials, according to the basic principle of electromagnetic wave propagation, the refractive index of a medium is related to the phase velocity of the electromagnetic wave in the medium. In ZIM, since the refractive index is close to zero, the phase velocity of the electromagnetic wave becomes very large or even infinite, resulting in a very small or almost zero phase change of the electromagnetic wave in the ZIM. This means that when the electromagnetic wave radiates from the ZIM to the surrounding medium, the phase change is very small, that is, the zero phase shift characteristic. Based on this characteristic, electromagnetic waves can be effectively controlled. Previous studies have proposed the application of zero-refractive-index metasurface materials in beam steering and the realization of low-cost high-gain antennas. However, previous studies have focused on using a near-zero dielectric constant to achieve a single zero-refractive-index frequency band, and have not been able to achieve high gain in multiple frequency bands.

[0004] For example, Chinese patent CN113690598A discloses a biomedical telemetry implantable high-gain antenna based on a near-zero refractive index metamaterial, which can solve the problem of low gain of general implantable antennas while keeping other technical indicators of biomedical telemetry implantable antennas basically unchanged. Specifically, the antenna operates in the 2.45GHz ISM band and has the advantages of miniaturization, low profile, high gain and biocompatibility. However, the shortcomings of this antenna are: the structure is relatively complex, involving multiple components, including an antenna radiating unit, a lower dielectric substrate, a metal floor, a metamaterial structure, a coaxial connector, two short-circuit pins and an upper dielectric substrate, which may increase manufacturing costs and design difficulties; and it is mainly aimed at the field of biomedical telemetry, limiting its application flexibility in other fields.

[0005] Chinese patent CN118099756A discloses a high-gain circularly polarized microstrip antenna based on a near-zero refractive index metamaterial. The antenna achieves pattern compression and improves the main direction gain by effectively combining a circularly polarized microstrip antenna with a near-zero refractive index metamaterial without substantially affecting the working performance of the source antenna. Specifically, the antenna cover is composed of three layers of identical near-zero refractive index-based electromagnetic metamaterials stacked tightly from top to bottom to achieve high gain. However, the shortcomings of this antenna are: the design is mainly for circular polarization and may not be suitable for applications that require other polarization modes; and the frequency is mainly for a specific frequency band and may not be suitable for broadband applications; in addition, although the gain of the antenna is improved through simulation optimization, the optimization process and results are not described in detail, and there may be certain uncertainties in actual applications.

[0006] In summary, the main problems of the existing technology are as follows: The application of zero-refractive-index metasurface materials is limited to a single frequency band: Most of the existing zero-refractive-index metasurface materials can only be applied to a single frequency band and lack frequency band adjustability, which limits the ability of the antenna to operate in multiple frequency bands. Summary of the invention

[0007] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a broadband high-gain antenna based on dual-frequency near-zero metamaterials, which mainly solves the limitations of high-gain antennas in the prior art in terms of multi-band operation capabilities and the single-band problem of zero-refractive-index metasurface materials. The present invention can achieve high-gain antenna design in multiple frequency bands to adapt to the rapid development of modern communication technology and the changing application scenarios.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A broadband high-gain antenna based on dual-band near-zero metamaterial, comprising:

[0010] at least one broadband patch antenna;

[0011] A dual-band zero-refractive-index metamaterial coating is located above the broadband patch antenna; the dual-band zero-refractive-index metamaterial coating is composed of multiple layers of periodically arranged dual-frequency zero-refractive-index metamaterial units, wherein each dual-frequency zero-refractive-index metamaterial unit is composed of a substrate and a metal pattern printed on the substrate, and the metal patterns on the front and back surfaces of the substrate constitute a complementary double-layer symmetrical resonant ring structure.

[0012] In one embodiment, the dual-frequency zero-refractive-index metamaterial units are periodically arranged in the X and Y directions to form a single-layer cladding, and multiple single-layer claddings are stacked in the Z-axis direction to form the dual-band zero-refractive-index metamaterial cladding, wherein the zero-refractive-index frequency bands of each single-layer cladding are not completely the same.

[0013] In one embodiment, the zero refractive index characteristics of the dual-frequency zero refractive index metamaterial unit are optimized by a fuzzy time neural network to achieve multi-band high gain in the 4-11 GHz frequency band, where the magnetic near-zero zero refractive index point frequency is a, the electric near-zero zero refractive index point frequency is b, a=5GHz±1GHz, b=10GHz±1GHz.

[0014] In one embodiment, the dual-band zero-refractive-index metamaterial coating is loaded above the antenna floor at a height corresponding to the electromagnetic wave wavelength of frequency b to achieve high gain in the magnetic near-zero zero-refractive-index point frequency band and the electric near-zero zero-refractive-index point frequency band, wherein the maximum gain in the main polarization is 16.82 dB, the 3dB gain bandwidth is 9.7-10.46 GHz, the sub-peak gain is 13.51 dB, and the 3dB gain bandwidth is 6.14-7.06 GHz; the maximum gain in the cross-polarization is 16.95 dB, the 3dB gain bandwidth is 9.38-10.41 GHz, the sub-peak gain is 13.77 dB, and the 3dB gain bandwidth is 5.12-6.69 GHz.

[0015] In one embodiment, the dual-band zero-refractive-index metamaterial coating is loaded on the antenna floor at a frequency of At the height corresponding to the wavelength of the electromagnetic wave, the antenna has a maximum gain of 12.77dB in the main polarization, and a 3dB gain bandwidth of 7.58-9.33GHz. It has a maximum gain of 14.42dB in the cross polarization, and a 3dB gain bandwidth of 7.23-9.2GHz.

[0016] In one embodiment, the metal pattern is a square patch with an annular groove and a plurality of strip grooves dug out, the annular groove is centered on the center of the square patch, and the strip grooves include:

[0017] A first strip groove connecting the annular groove and the midpoint of one side of the square patch;

[0018] A second strip groove connecting the annular groove and the midpoint of the other side of the square patch, the first strip groove and the second strip groove are symmetrical, and two adjacent dual-frequency zero-refractive index metamaterial units in the Y direction are connected in a straight line through the first strip groove and the second strip groove;

[0019] A third strip groove connecting two diagonal corners of the square patch;

[0020] The fourth strip grooves at the other two diagonals of the square patch are connected, and the fourth strip grooves have the same shape and size as the third strip grooves. Two adjacent dual-frequency zero-refractive index metamaterial units in the X direction and two adjacent dual-frequency zero-refractive index metamaterial units in the Y direction are cross-connected through the third strip groove and the fourth strip groove.

[0021] In one embodiment, the fourth strip groove and the third strip groove have a groove width of IW in the annular groove and a groove width of OW in the outer portion of the annular groove, and IW≠OW.

[0022] The present invention also provides a design method for the broadband high-gain antenna based on the dual-frequency near-zero metamaterial, comprising the following steps:

[0023] Design a dual-frequency zero-refractive-index metamaterial unit with near-zero permittivity and near-zero permeability properties;

[0024] Cascading the dual-band zero-refractive-index metamaterial units to construct the dual-band zero-refractive-index metamaterial cladding;

[0025] The height at which the dual-band zero-refractive-index metamaterial cladding is loaded on the broadband patch antenna is adjusted to achieve broadband high gain or dual-band high gain.

[0026] In one embodiment, the method for designing a dual-frequency zero-refractive-index metamaterial unit having near-zero dielectric constant and near-zero magnetic permeability is as follows:

[0027] Unit No. 1, unit No. 2 and unit No. 3 having the same shape are defined, wherein unit No. 1 is an initial unit that satisfies the dual-frequency zero refractive index characteristic and is used to construct a metamaterial cladding and provide a basis for parameter optimization of unit No. 2 and unit No. 3, and unit No. 2 and unit No. 3 are designed according to a target S-curve so that their magnetic near-zero zero refractive index point frequency is a and their electric near-zero zero refractive index point frequency is b, so as to achieve zero refractive index characteristics in a specific frequency band, a=5GHz±1GHz, b=10GHz±1GHz.

[0028] In one embodiment, the metal pattern is a square patch with an annular groove and a plurality of strip grooves dug out, the annular groove is centered on the center of the square patch, and the strip grooves include:

[0029] A first strip groove connecting the annular groove and the midpoint of one side of the square patch;

[0030] A second strip groove connecting the annular groove and the midpoint of the other side of the square patch, the first strip groove and the second strip groove are symmetrical, and two adjacent dual-frequency zero-refractive index metamaterial units in the Y direction are connected in a straight line through the first strip groove and the second strip groove;

[0031] A third strip groove connecting two diagonal corners of the square patch;

[0032] A fourth strip groove connecting the other two diagonal corners of the square patch, the fourth strip groove having the same shape and size as the third strip groove, and two adjacent dual-frequency zero-refractive index metamaterial units in the X direction and two adjacent dual-frequency zero-refractive index metamaterial units in the Y direction are cross-connected through the third strip groove and the fourth strip groove;

[0033] The fourth strip groove and the third strip groove have a groove width of IW in the annular groove and a groove width of OW outside the annular groove. For the first unit, OW is 4 mm and IW is 3 mm; for the second unit, OW is 2 mm and IW is 1.5 mm; for the third unit, OW is 0.6 mm and IW is 2 mm.

[0034] The single-layer covering formed by unit No. 1 is closest to the broadband patch antenna, the single-layer covering formed by unit No. 3 is farthest from the broadband patch antenna, and the single-layer covering formed by antenna No. 2 is located between the single-layer coverings formed by units No. 1 and No. 3.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] First, an antenna design capable of achieving high gain in multiple frequency bands is provided, which increases the frequency band adjustability and application range of the antenna. The high-gain antenna of the present invention has better gain in both frequency bands, wherein the maximum gain in the main polarization is 16.82dB, the 3dB gain bandwidth is 9.7-10.46GHz, the sub-peak gain is 13.51dB, and the 3dB gain bandwidth is 6.14-7.06GHz. In cross polarization, the maximum gain is 16.95dB, the 3dB gain bandwidth is 9.38-10.41GHz, the sub-peak gain is 13.77dB, and the 3dB gain bandwidth is 5.12-6.69GHz.

[0037] Second, by calculating and optimizing the parameters, the zero refractive index characteristic of the antenna in a specific frequency band is achieved, thereby improving the gain and performance of the antenna.

[0038] Third, the designed DBZRI-MC has a simple structure and is easy to manufacture, which reduces the cost while improving the performance and reliability of the antenna.

[0039] Fourth, the conversion of the spherical wave emitted by the antenna into a plane wave is realized, further improving the gain of the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the DBZRI-MU structure of the present invention.

[0041] Figure 2 Schematic diagram of the DBZRI-MC structure of the present invention.

[0042] Figure 3 Schematic diagram of the transmission characteristics and refractive index of DBZRI-MU of the present invention.

[0043] Figure 4 Schematic diagram of three sets of expected S curves.

[0044] Figure 5 Schematic diagram of the transmission curves and refractive index curves of three groups of DBZRI-MU.

[0045] Figure 6 Schematic diagram of the feed antenna.

[0046] Figure 7 This is the gain diagram of the antenna system when the loading height is 30mm.

[0047] Figure 8 This is the gain diagram of the antenna system when the loading height is 20mm. DETAILED DESCRIPTION

[0048] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0049] The present invention is a broadband high-gain antenna based on a dual-band near-zero metamaterial, which includes a broadband patch antenna and a dual-band zero-refractive index metamaterial composite (DBZRI-MC), wherein the DBZRI-MC is located above the broadband patch antenna. Figure 1 and attached Figure 2 As shown in FIG. 1 , it is composed of multiple layers of periodically arranged dual-band zero-refractive index metamaterial units (DBZRI-MU). Specifically, Figure 1 , Figure 2 In the structure shown, multiple DBZRI-MUs are periodically arranged in the X and Y directions to form a single-layer coating, and multiple single-layer coatings are stacked in the Z-axis direction to form a DBZRI-MC. Each DBZRI-MU is composed of a substrate and a metal pattern printed on the substrate, and the metal patterns on the front and back of the substrate form a complementary double-layer symmetrical resonant ring structure.

[0050] In the embodiment of the present invention, for each single-layer coating, the number of DBZRI-MUs in the X direction is preferably 3, the number of DBZRI-MUs in the Y direction is preferably 3, and the number of single-layer coatings stacked in the Z-axis direction is preferably 4. Thus, a DBZRI-MC structure with 4 layers and 9 DBZRI-MUs in each layer is formed. In application, the 4-layer structure can be formed by printing the above-mentioned metal pattern on 3 substrates, with the substrates at both ends printed on the inner side and the substrate in the middle printed on the front and back sides.

[0051] The embodiment of the present invention provides a form of the above metal pattern, such as Figure 1 and Figure 2As shown, a circular groove and a plurality of strip grooves are dug out from a square patch. The center of the circular groove coincides with the center of the square patch, and the strip grooves include a first strip groove, a second strip groove, a third strip groove and a fourth second strip groove. The first strip groove and the second strip groove are symmetrically arranged, with the same shape and size, and respectively connect the midpoint of one side of the square patch with the circular groove, and the midpoint of the opposite side of the square patch with the circular groove. In an embodiment of the present invention, the first strip groove and the second strip groove are both arranged along the Y direction and symmetrical along the X direction. Between two adjacent DBZRI-MUs in the Y direction, the first strip groove and the second strip groove are connected in a straight line.

[0052] The third strip groove and the fourth strip groove respectively connect the two diagonals of the square patch, and the shapes and sizes of the two are straight and symmetrical. In an embodiment of the present invention, the third strip groove and the fourth strip groove are both at an angle of 45° with the X direction and the Y direction, and the two adjacent DBZRI-MUs in the X direction and the two adjacent DBZRI-MUs in the Y direction are cross-connected through the third strip groove and the fourth strip groove. That is, if the X direction is a row and the Y direction is a column, the four DBZRI-MUs adjacent in the rows and columns are located at the four vertices of a square, and the four DBZRI-MUs are connected in a cross structure from the center of the square, and the connection points are located at the third strip groove and the fourth strip groove.

[0053] Furthermore, the zero refractive index frequency bands of the single-layer claddings of the present invention are not completely the same. In this embodiment, specifically, the fourth strip groove and the third strip groove, the groove width of the portion inside the annular groove is IW, and the groove width of the portion outside the annular groove is OW, IW≠OW, and the OW value and IW value of DBZRI-MU in the same single-layer cladding are the same, but the OW and IW of DBZRI-MU in different single-layer claddings are not completely the same.

[0054] In an embodiment of the present invention, the zero refractive index characteristics of DBZRI-MU are optimized by Fourier transform neural network (FTNN), including discretizing the target S-curve data, simplifying the S-curve data using Fourier transform method, inferring the corresponding structural parameters from the simplified data using inverse neural network, and finally calculating and verifying the inferred structural parameters by forward neural network to achieve multi-band high gain in the 4-11GHz frequency band, wherein the magnetic near-zero refractive index point frequency is 5GHz±1GHz, and the electric near-zero refractive index point frequency is 10GHz±1GHz. The high-gain antenna of the present invention can be designed by the following method:

[0055] Firstly, a DBZRI-MU with near-zero dielectric constant and near-zero magnetic permeability characteristics is designed, and the dual-frequency zero refractive index characteristics of DBZRI-MU are utilized to achieve a good gain improvement.

[0056] The designed DBZRI-MU was cascaded in the X and Y directions to construct a single-layer cladding.

[0057] The single-layer cladding is stacked in the Z direction to construct the required DBZRI-MC.

[0058] Adjust the height at which DBZRI-MC is loaded on the broadband patch antenna to achieve broadband high gain or dual-band high gain.

[0059] See attached Figure 3 , the transmission characteristics of DBZRI-MU and the influence of refractive index on antenna gain are analyzed. In one embodiment of the present invention, the gain improvement utilizes the dual-frequency zero refractive index characteristics of DBZRI-MU. Therefore, in order to achieve a good gain improvement, FTNN should be used to find three DBZRI-MUs with different zero refractive index frequencies to cascade to form DBZRI-MC. Figure 3 It can be seen that the near-zero frequency band of its zero refractive index has a mapping relationship with the S21 curve. The two troughs of the S21 curve correspond to two strong negative electric resonance points and strong negative magnetic resonance points, which constitute the transmission stopband. The magnetic near-zero refractive index point is the peak point of the transmission stopband. The high-frequency trough of the S11 curve corresponds to the electric near-zero refractive index point. Figure 3 The S-curve of DBZRI-MC is used to design unit No. 1. In the future, the zero refractive index characteristics of DBZRI-MC will be used to achieve dual-frequency high gain or single-frequency broadband high gain. Therefore, it is necessary to use FTNN to optimize three groups of DBZRI-MU to make them have the following properties: the magnetic near-zero zero refractive index point is around 5 GHz, and the electric near-zero zero refractive index point is around 10 GHz; a total of 6 zero refractive index points are spaced within 4-11 GHz.

[0060] See attached Figure 4 The present invention selects two sets of expected S curves as the second and third units, and selects the initial model of the design as the first unit, and then finds its corresponding structural parameters. The three types of units have the same shape. Figure 4 The target S curve is designed so that its magnetic near-zero refractive index point frequency is about 5 GHz and its electric near-zero refractive index point frequency is about 10 GHz, so as to achieve zero refractive index characteristics in a specific frequency band. The structural parameters obtained by FTNN calculation are:

[0061]

[0062] See attached Figure 5 , the transmission performance and refractive index of three groups of DBZRI-MU were simulated, and finally the structural parameters of the three units were determined by comprehensively considering factors such as the manufacturing process as shown in the table.

[0063]

[0064] The single-layer coating composed of unit No. 1 is named single-layer coating 1, the single-layer coating composed of unit No. 2 is named single-layer coating 2, and the single-layer coating composed of unit No. 3 is named single-layer coating 3. The present invention uses 4 layers of single-layer coatings, which are single-layer coating 1, single-layer coating 2, single-layer coating 2 and single-layer coating 3 in the direction away from the broadband patch antenna.

[0065] See attached Figure 6 As shown, an L-slot patch antenna is used as a feed antenna in one embodiment of the present invention. The L-slot patch antenna is composed of two rectangular patches, two feed lines, three dielectric substrate layers and an optimized L-shaped cavity back ground plane. The dielectric substrate layer 1 is located at the top of the antenna, the radiation patch is placed between the dielectric substrate layer 1 and the dielectric substrate layer 2, the two rectangular patches are respectively located below the dielectric substrate layer 2 and the dielectric substrate layer 3, the two feed lines are vertically placed on the dielectric substrate layer 3, and the feed lines are connected to the inner conductor of the coaxial line at the port. The antenna is fed by close coupling between the patch and the feed line. A ground plane with an L-shaped cavity is set under the antenna, which can increase the coupling between the feed line and the radiation patch, thereby improving the impedance bandwidth. In addition, the dielectric substrate layer 1 serves as a dielectric matching layer of the patch, further broadening the bandwidth of the antenna. The dielectric substrate layer 2, which is thicker than the dielectric substrate layer 1, increases the bandwidth by increasing the radiation resistance, while the dielectric substrate layer 3, which is thinner than the dielectric substrate layer 1, reduces the undesired stray radiation generated by the feed line. The three dielectric substrate layers are all made of commonly used FR4 material with a dielectric constant of 2.2.

[0066] See attached Figure 7 , the DBZRI-MC composed of the above-mentioned single-layer coating one, single-layer coating two, single-layer coating two and single-layer coating three is loaded to 30mm (i.e., the height of the 10GHz electromagnetic wave wavelength) from the antenna ground to achieve overall high gain in the magnetic near-zero refractive index point frequency band and the electric near-zero refractive index point frequency band. The antenna is a dual-polarization dual-band antenna with a maximum gain of 16.82dB in the main polarization, a 3dB gain bandwidth of 9.7-10.46GHz, a sub-peak gain of 13.51dB, and a 3dB gain bandwidth of 6.14-7.06GHz. In cross-polarization, the maximum gain is 16.95dB, the 3dB gain bandwidth is 9.38-10.41GHz, the sub-peak gain is 13.77dB, and the 3dB gain bandwidth is 5.12-6.69GHz.

[0067] Further, see the attached Figure 8, DBZRI-MC is loaded at a distance of 20mm from the antenna floor, that is, at the half-wavelength height of the 7.5GHz electromagnetic wave. Analysis of the simulation results shows that the antenna is a dual-polarized antenna with a maximum gain of 12.77dB in the main polarization and a 3dB gain bandwidth of 7.58-9.33GHz. The maximum gain in cross polarization is 14.42dB, and the 3dB gain bandwidth is 7.23-9.2GHz.

[0068] It can be seen that by optimizing the structural parameters of the metamaterial unit after calculation, the present invention achieves multi-band high gain in the 4-11 GHz frequency band. In particular, the magnetic near-zero refractive index point is near 5 GHz, and the electric near-zero refractive index point is near 10 GHz, so that the antenna can provide high gain performance in both frequency bands.

[0069] In summary, the present invention places the DBZRI-MC composed of the designed multi-layer cascade structure unit DBZRI-MU above the broadband patch antenna, so that the improved antenna has better gain in both frequency bands. It can meet the needs of satellite communications, radar, radio direction finding, aviation communications and other fields for fast and high-gain antennas, especially in scenarios that require rapid response and deployment. At the same time, the antenna of the present invention has a simple structure and is easy to manufacture, which reduces costs and improves the performance and reliability of the antenna. Through the design of the metamaterial coating, the conversion of spherical waves emitted by the antenna to plane waves is achieved, further improving the gain of the antenna.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, replacements and improvements made within the present invention should be included in the protection scope of the present invention.

Claims

1. A broadband high-gain antenna based on dual-band near-zero metamaterial, characterized in that: include: at least one broadband patch antenna; a dual-band zero-index metamaterial cladding located above the broadband patch antenna; The dual-band zero-refractive-index metamaterial coating is composed of multiple layers of periodically arranged dual-frequency zero-refractive-index metamaterial units, wherein each dual-frequency zero-refractive-index metamaterial unit is composed of a substrate and a metal pattern printed on the substrate, and the metal patterns on the front and back surfaces of the substrate form a complementary double-layer symmetrical resonant ring structure.

2. The broadband high-gain antenna based on dual-frequency near-zero metamaterial according to claim 1, characterized in that: The dual-frequency zero-refractive-index metamaterial units are periodically arranged in the X and Y directions to form a single-layer coating, and multiple single-layer coatings are stacked in the Z-axis direction to form the dual-band zero-refractive-index metamaterial coating, wherein the zero-refractive-index frequency bands of each single-layer coating are not completely the same.

3. The broadband high-gain antenna based on dual-frequency near-zero metamaterial according to claim 1, characterized in that: The zero refractive index characteristics of the dual-frequency zero refractive index metamaterial unit are optimized by a fuzzy time neural network to achieve multi-band high gain in the 4-11 GHz frequency band, where the magnetic near-zero zero refractive index point frequency is a, the electric near-zero zero refractive index point frequency is b, a=5GHz±1GHz, b=10GHz±1GHz.

4. The broadband high-gain antenna based on dual-frequency near-zero metamaterial according to claim 3, characterized in that: The dual-band zero-refractive-index metamaterial cladding is loaded above the antenna floor at a height corresponding to the electromagnetic wave wavelength of frequency b to achieve high gain in the magnetic near-zero zero-refractive-index point frequency band and the electric near-zero zero-refractive-index point frequency band, wherein in the main polarization, the maximum gain is 16.82 dB, the 3dB gain bandwidth is 9.7-10.46 GHz, the sub-peak gain is 13.51 dB, and the 3dB gain bandwidth is 6.14-7.06 GHz; in the cross-polarization, the maximum gain is 16.95 dB, the 3dB gain bandwidth is 9.38-10.41 GHz, the sub-peak gain is 13.77 dB, and the 3dB gain bandwidth is 5.12-6.69 GHz.

5. The broadband high-gain antenna based on dual-frequency near-zero metamaterial according to claim 3, characterized in that: The dual-band zero-refractive-index metamaterial coating is loaded above the antenna floor. At the height corresponding to the wavelength of the electromagnetic wave, the antenna has a maximum gain of 12.77dB in the main polarization, and a 3dB gain bandwidth of 7.58-9.33GHz. It has a maximum gain of 14.42dB in the cross polarization, and a 3dB gain bandwidth of 7.23-9.2GHz.

6. The broadband high-gain antenna based on dual-frequency near-zero metamaterial according to any one of claims 1 to 5, characterized in that: The metal pattern is a square patch with an annular groove and multiple strip grooves dug out, the annular groove is centered on the center of the square patch, and the strip grooves include: A first strip groove connecting the annular groove and the midpoint of one side of the square patch; A second strip groove connecting the annular groove and the midpoint of the other side of the square patch, the first strip groove and the second strip groove are symmetrical, and two adjacent dual-frequency zero-refractive index metamaterial units in the Y direction are connected in a straight line through the first strip groove and the second strip groove; A third strip groove connecting two diagonal corners of the square patch; The fourth strip grooves at the other two diagonals of the square patch are connected, and the fourth strip grooves have the same shape and size as the third strip grooves. Two adjacent dual-frequency zero-refractive index metamaterial units in the X direction and two adjacent dual-frequency zero-refractive index metamaterial units in the Y direction are cross-connected through the third strip groove and the fourth strip groove.

7. The broadband high-gain antenna based on dual-frequency near-zero metamaterial according to claim 6, characterized in that: The fourth strip groove and the third strip groove have a groove width of IW in the annular groove and a groove width of OW in the outer portion of the annular groove, and IW≠OW.

8. The design method of a broadband high-gain antenna based on a dual-frequency near-zero metamaterial according to any one of claims 1 to 7, characterized in that: The following steps are involved: Design a dual-frequency zero-refractive-index metamaterial unit with near-zero permittivity and near-zero permeability properties; Cascading the dual-band zero-refractive-index metamaterial units to construct the dual-band zero-refractive-index metamaterial cladding; The height at which the dual-band zero-refractive-index metamaterial cladding is loaded on the broadband patch antenna is adjusted to achieve broadband high gain or dual-band high gain.

9. The design method of a broadband high-gain antenna based on dual-frequency near-zero metamaterial according to claim 8, characterized in that: The method for designing a dual-frequency zero-refractive-index metamaterial unit having near-zero dielectric constant and near-zero magnetic permeability is as follows: Unit No. 1, unit No. 2 and unit No. 3 having the same shape are defined, wherein unit No. 1 is an initial unit that satisfies the dual-frequency zero refractive index characteristic and is used to construct a metamaterial cladding and provide a basis for parameter optimization of unit No. 2 and unit No. 3, and unit No. 2 and unit No. 3 are designed according to a target S-curve so that their magnetic near-zero zero refractive index point frequency is a and their electric near-zero zero refractive index point frequency is b, so as to achieve zero refractive index characteristics in a specific frequency band, a=5GHz±1GHz, b=10GHz±1GHz.

10. The design method of a broadband high-gain antenna based on dual-frequency near-zero metamaterial according to claim 8, characterized in that: The metal pattern is a square patch with an annular groove and multiple strip grooves dug out, the annular groove is centered on the center of the square patch, and the strip grooves include: A first strip groove connecting the annular groove and the midpoint of one side of the square patch; A second strip groove connecting the annular groove and the midpoint of the other side of the square patch, the first strip groove and the second strip groove are symmetrical, and two adjacent dual-frequency zero-refractive index metamaterial units in the Y direction are connected in a straight line through the first strip groove and the second strip groove; A third strip groove connecting two diagonal corners of the square patch; A fourth strip groove connecting the other two diagonal corners of the square patch, the fourth strip groove having the same shape and size as the third strip groove, and two adjacent dual-frequency zero-refractive index metamaterial units in the X direction and two adjacent dual-frequency zero-refractive index metamaterial units in the Y direction are cross-connected through the third strip groove and the fourth strip groove; The fourth strip groove and the third strip groove have a groove width of IW in the annular groove and a groove width of OW outside the annular groove. For the first unit, OW is 4 mm and IW is 3 mm; for the second unit, OW is 2 mm and IW is 1.5 mm; for the third unit, OW is 0.6 mm and IW is 2 mm. The single-layer covering formed by unit No. 1 is closest to the broadband patch antenna, the single-layer covering formed by unit No. 3 is farthest from the broadband patch antenna, and the single-layer covering formed by antenna No. 2 is located between the single-layer coverings formed by units No. 1 and No. 3.

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