A high-gain antenna implementation method based on polarization-insensitive metasurface

Abstract

The application provides a high-gain antenna implementation method based on a polarization-insensitive metasurface, wherein the polarization-insensitive metasurface is composed of a plurality of metasurface unit structures with the same structure arranged periodically; the metasurface unit structure comprises a dielectric substrate and a plurality of metal patches etched on a surface of the dielectric substrate; the key physical dimension of the cross-shaped metasurface unit is controlled to realize the electric resonance and magnetic resonance characteristics of the cross-shaped metasurface unit, and the wideband near-zero refractive index is realized. When the cross-shaped metasurface unit is loaded on a microstrip antenna as a coating, the gain of the antenna can be significantly improved by optimizing the loading height and increasing the number of layers, and the method is effective for linearly polarized antennas and circularly polarized antennas, and provides a new solution for improving the gain of antennas under various polarization conditions.

Description

Technical Field

[0001] This invention relates to the field of metasurface antenna technology, and in particular to a method for realizing a high-gain antenna based on a polarization-insensitive metasurface. Background Technology

[0002] Antennas play a crucial role in radio systems such as radar and communications, and their performance directly impacts the overall operational performance of these systems. Gain is a very important indicator of antenna characteristics; high-gain antennas significantly improve the efficiency and accuracy of signal transmission. Therefore, improving antenna gain is of great practical significance.

[0003] Metasurface antennas can improve certain characteristics by loading metasurface structures, such as extending the antenna's operating bandwidth, reducing its RCS, and increasing its gain. However, given the increasingly complex nature of wireless transmission systems, making metasurfaces suitable for improving antenna gain under various polarization conditions remains of great significance and presents certain challenges. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing a method for implementing a high-gain antenna based on a polarization-insensitive metasurface, which can improve antenna gain under multi-polarization conditions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a method for implementing a high-gain antenna based on a polarization-insensitive metasurface, wherein the polarization-insensitive metasurface is composed of a periodically arranged plurality of metasurface unit structures with identical structures;

[0007] The metasurface unit structure includes: a dielectric substrate and a plurality of metal patches etched on one surface of the dielectric substrate;

[0008] The metal patch includes four metal arms, each of which includes two strip-shaped metal patches and one semi-circular metal patch. The semi-circular metal patch is arranged such that the semi-circular metal patch connecting the tops of the two strip-shaped metal arms is rotated 90 degrees around a third direction.

[0009] The strip-shaped metal patches of the four metal arms are connected to form a cross-shaped pattern.

[0010] Furthermore, the third direction is perpendicular to the plane where the dielectric substrate is located. The plane where the dielectric substrate is located has a first direction and a second direction, which are set at a perpendicular angle. The third direction is the normal direction of the plane.

[0011] Furthermore, the two strip-shaped metal patches are arranged parallel to each other and spaced apart;

[0012] One end of the semi-circular metal patch is connected to one end of one of the strip-shaped metal patches, and the other end of the semi-circular metal patch is connected to one end of another strip-shaped metal patch.

[0013] Furthermore, two of the metal arms are parallel to the second direction, and the other two metal arms are parallel to the first direction.

[0014] Furthermore, in the metasurface unit structure, each of the strip-shaped metal patches has the same size, and each of the semi-circular metal patches has the same size.

[0015] Furthermore, in the plurality of polarization-insensitive metasurfaces, multiple metasurface unit structures overlap in the third direction; in the plurality of polarization-insensitive metasurfaces, multiple metasurface unit structures are periodically arranged in the first direction and the second direction to form a periodic polarization-insensitive metasurface.

[0016] Furthermore, the polarization-insensitive metasurface is applied as a coating onto the antenna.

[0017] The beneficial effects of this invention are as follows: by controlling the electric and magnetic resonance characteristics of the cross-shaped metasurface unit through key physical dimensions, a broadband near-zero refractive index is achieved. When used as a cladding layer on a microstrip antenna, the antenna gain can be significantly improved by optimizing the loading height and increasing the number of layers, and this is effective for both linearly polarized and circularly polarized antennas, providing a new solution for improving antenna gain under various polarization conditions. Attached Figure Description

[0018] Figure 1 This is a structural diagram of a metasurface unit structure;

[0019] Figure 2 The curve showing the change of parameter S amplitude with frequency obtained from the simulation of Example 1;

[0020] Figure 3 The parameter S is the phase-frequency variation curve obtained from the simulation of Example 1;

[0021] Figure 4 The real part of the equivalent electromagnetic parameters in Example 1;

[0022] Figure 5 This represents the imaginary part of the equivalent electromagnetic parameters in Example 1.

[0023] Figure 6 Example 2 shows a microstrip antenna with a single-layer metasurface coating.

[0024] Figure 7 The reflection coefficient curves of the antenna before and after the cladding loading in Example 2 are shown.

[0025] Figure 8 The gain curves of the antenna before and after the cladding loading in Example 2 are shown.

[0026] Figure 9 Example 2 shows a microstrip antenna with a double-layer metasurface coating.

[0027] Figure 10 The reflection coefficients of the antenna before and after the double-layer loading in Example 2;

[0028] Figure 11 The gain curves of the antenna before and after double-layer loading in Example 2 are shown.

[0029] Figure 12 Example 3: Circularly polarized antenna array;

[0030] Figure 13 The curves showing the variation of the reflection coefficient of the circularly polarized antenna with frequency before and after the double-layer coating loading in Example 3 are shown.

[0031] Figure 14 The curves showing the axial ratio of the circularly polarized antenna before and after double-layer cladding loading in Example 3 are as follows:

[0032] Figure 15 The gain curve of the circularly polarized antenna before and after the double-layer coating is shown in Example 3. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] A method for realizing a high-gain antenna based on a polarization-insensitive metasurface, wherein the polarization-insensitive metasurface is composed of multiple metasurface unit structures with identical structures arranged periodically;

[0035] The metasurface unit structure includes: a dielectric substrate and a plurality of metal patches etched on one surface of the dielectric substrate;

[0036] The metal patch includes four metal arms, each of which includes two strip-shaped metal patches and one semi-circular metal patch. The semi-circular metal patch is arranged such that the semi-circular metal patch connecting the tops of the two strip-shaped metal arms is rotated 90 degrees around a third direction.

[0037] The strip-shaped metal patches of the four metal arms are connected to form a cross-shaped pattern.

[0038] The third direction is perpendicular to the plane on which the dielectric substrate is located. The plane on which the dielectric substrate is located has a first direction and a second direction, which are set at a perpendicular angle. The third direction is the normal direction of the plane.

[0039] The two strip-shaped metal patches are arranged parallel to each other and spaced apart.

[0040] One end of the semi-circular metal patch is connected to one end of one of the strip-shaped metal patches, and the other end of the semi-circular metal patch is connected to one end of another strip-shaped metal patch.

[0041] Two of the metal arms are parallel to the second direction, and the other two metal arms are parallel to the first direction.

[0042] In the metasurface unit structure, each strip of metal patch has the same size, and each semi-circular metal patch has the same size.

[0043] In a plurality of polarization-insensitive metasurfaces, multiple metasurface unit structures overlap in the third direction; in a plurality of polarization-insensitive metasurfaces, multiple metasurface unit structures are periodically arranged in the first direction and the second direction to form a periodic polarization-insensitive metasurface.

[0044] The polarization-insensitive metasurface is applied as a cladding layer onto the antenna.

[0045] Example 1

[0046] The metasurface unit structure includes: a dielectric substrate 5 and several metal patches on one surface of the dielectric substrate 5.

[0047] The dielectric substrate 5 extends along the first direction F1 and the second direction F2.

[0048] Each metal patch is cross-shaped and includes four metal arms. Each metal arm includes two strip-shaped metal patches and one semi-circular metal patch. The semi-circular metal patch is arranged such that the semi-circular metal patch connecting the tops of the two strip-shaped metal arms is rotated 90 degrees around a third direction.

[0049] Please see Figure 1In this embodiment, the first metal arm 1 includes a first strip-shaped metal patch 101 and a second strip-shaped metal patch 102. The first strip-shaped metal patch 101 and the second strip-shaped metal patch 102 are spaced apart and are parallel to the first direction F1. After the first semi-circular metal patch 601 is rotated 90 degrees around the third direction F3, one end of the first semi-circular metal patch 601 is connected to the k end of the first strip-shaped metal patch 101, and the other end of the first semi-circular metal patch 601 is connected to the k end of the second strip-shaped metal patch 102.

[0050] The second metal arm 2 includes a third strip-shaped metal patch 103 and a fourth strip-shaped metal patch 104. The third strip-shaped metal patch 103 and the fourth strip-shaped metal patch 104 are spaced apart and are parallel to the second direction F2. After the second semi-circular metal patch 602 is rotated 90 degrees around the third direction F3, one end of the second semi-circular metal patch 602 is connected to the k end of the third strip-shaped metal patch 103, and the other end of the second semi-circular metal patch 602 is connected to the k end of the fourth strip-shaped metal patch 104.

[0051] The j-end of the first strip-shaped metal patch 101 is connected to the j-end of the third strip-shaped metal patch 103.

[0052] The third metal arm 3 includes a fifth strip-shaped metal patch 105 and a sixth strip-shaped metal patch 106. The fifth strip-shaped metal patch 105 and the sixth strip-shaped metal patch 106 are spaced apart and are parallel to the first direction F1. After the third semi-circular metal patch 603 is rotated 90 degrees around the third direction F3, one end of the third semi-circular metal patch 603 is connected to the k end of the fifth strip-shaped metal patch 105, and the other end of the third semi-circular metal patch 603 is connected to the k end of the sixth strip-shaped metal patch 106.

[0053] The j-end of the fifth strip metal patch 105 is connected to the j-end of the fourth strip metal patch 104.

[0054] The fourth metal arm 4 includes a seventh strip metal patch 107 and an eighth strip metal patch 108, which are spaced apart and are parallel to the second direction F2. After the fourth semi-circular metal patch 604 is rotated 90 degrees around the third direction F3, one end of the fourth semi-circular metal patch 604 is connected to the k end of the seventh strip metal patch 107, and the other end of the fourth semi-circular metal patch 604 is connected to the k end of the eighth strip metal patch 108.

[0055] The j-end of the sixth strip metal patch 106 is connected to the j-end of the seventh strip metal patch 107, and the j-end of the eighth strip metal patch 108 is connected to the j-end of the second strip metal patch 102.

[0056] The first metal arm 1 and the third metal arm 3 are symmetrically arranged, and the second metal arm 2 and the fourth metal arm 4 are symmetrically arranged.

[0057] In this embodiment, the dielectric substrate has a relative permittivity of 2.2 and a thickness of 0.5 mm;

[0058] In this embodiment, the lengths of the first metal arm 1, the second metal arm 2, the third metal arm 3, and the fourth metal arm 4 are a; among the metal arms, the distance between the two metal arms is b, the width of the strip metal arm is w, and the length of a single metasurface unit structure is p.

[0059] The values ​​for each parameter are shown in the table below.

[0060] Table 1 shows the values ​​of each parameter.

[0061]

[0062] The amplitude and phase curves of the scattering parameters S11 and S21 of the polarization-insensitive metasurface as a function of frequency are shown below. Figure 2 and Figure 3 As shown.

[0063] After obtaining the parameter S, the parameter S-inversion method is used for calculation. The relationship between the refractive index n-wave impedance η and the S-parameter is:

[0064] (1);

[0065] (2);

[0066] Furthermore, the dielectric constant ε and magnetic permeability μ of the polarization-insensitive metasurface are obtained, and the specific calculation formulas are as follows:

[0067] (3);

[0068] (4);

[0069] Substituting the simulated parameter S into formulas (1)~(4), the equivalent electromagnetic parameters of the metasurface unit are obtained as follows: Figure 4 and Figure 5 As shown.

[0070] from Figure 4As can be seen from the real parts of the equivalent electromagnetic parameters shown, the dielectric constant ε of this metasurface unit structure is less than 1 in the range of 5.4 GHz to 10 GHz, the permeability μ is less than 1 in the range of 4 GHz to 7.7 GHz, and the refractive index n, which has an important influence on the propagation of electromagnetic waves, is less than 1 in the wide bandwidth range of 4.3 GHz to 10 GHz, and is almost 0 in the range of 5.9 GHz to 8.3 GHz, indicating that this metasurface structure has broadband zero refractive index characteristics.

[0071] Figure 5 The imaginary part of the electromagnetic parameters shown represents the propagation loss. It can be seen that in the frequency range of 4 GHz to 8.4 GHz, the imaginary part of the permittivity ε and the permeability μ is 0, while the imaginary part of the refractive index n is 0 in the range of 4 GHz to 5.9 GHz and less than 1 in the range of 5.9 GHz to 8.3 GHz, which corresponds to the frequency range where the real part is close to 0. This indicates that the designed structure has low loss characteristics while achieving near-zero refractive index.

[0072] Example 2

[0073] In a plurality of polarization-insensitive metasurfaces, multiple metasurface unit structures overlap in the third direction; in a plurality of polarization-insensitive metasurfaces, multiple metasurface unit structures are periodically arranged in the first direction and the second direction to form a periodic polarization-insensitive metasurface.

[0074] like Figure 6 As shown, the original antenna is a microstrip antenna element with a resonant frequency of 6.7 GHz. The antenna aperture size is 30 mm × 30 mm. Two metasurface unit structures are arranged along the first direction F1 and the second direction F2, respectively, forming a 2 × 2 array layout, which is also 30 mm × 30 mm in size. The loading height is set as h, where h represents the distance between the lower surface of the cladding and the ground plane of the microstrip antenna element.

[0075] The initial loading height h was chosen to be 23mm (half the wavelength corresponding to 6.7GHz). By optimizing the value of h to achieve the best radiation characteristics for the antenna, the final value of h was determined to be 30mm. At this point, the reflection coefficient curve S11 and gain curve of the antenna before and after loading the metasurface cladding are as follows: Figure 7 and Figure 8 As shown. By Figure 7 It can be seen that the original antenna's -10dB operating bandwidth is 6.5GHz~6.9GHz, while the -10dB operating bandwidth after the coating is applied is 6.4GHz~6.8GHz, showing a slight shift towards lower frequencies. Figure 8 It can be seen that the antenna gain was significantly improved after the coating was applied, with a maximum improvement of 2.4dB.

[0076] Please see Figure 9 A double-layer loading method is adopted, with a height of h1 between the two layers. Optimizing the loading height h1 based on h=30mm can further improve the antenna gain. When h=30mm and h1=11mm, the radiation characteristics of the double-layered antenna and the original antenna are as follows: Figure 10 and Figure 11 As shown in the figure, the -10dB operating bandwidth of the antenna after adding the double cladding remains 6.4GHz~6.8GHz, but the maximum gain is increased by 4.3dB, representing a further improvement compared to the single-cladding antenna. It should be noted that although the antenna polarization is x-polarized at this point, due to the rotational symmetry of the designed metasurface structure, the same gain improvement will be achieved for the y-polarized antenna.

[0077] Example 3

[0078] like Figure 12 As shown, the antenna achieves circular polarization by chamfering the microstrip antenna and loading a double-layer metasurface. The antenna gain is improved by optimizing the loading height of the double layer. The optimized layer height is: h=25mm, h1=9mm. Figure 13 and Figure 14 The figures show the curves of the antenna's reflection coefficient S11 and axial ratio as a function of frequency before and after the cladding is applied.

[0079] The original antenna has a bandwidth of 6.1GHz to 6.4GHz that satisfies both a reflection coefficient of less than -10dB and an axial ratio of less than 3dB. After adding a double-layer metasurface coating, the bandwidth still satisfies both a reflection coefficient of less than -10dB and an axial ratio of less than 3dB. Figure 15 The figure shows the gain curves of the antenna before and after the double-layer coating in the above frequency band. It can be seen that the gain is significantly improved throughout the entire operating frequency band, with a maximum increase of 3.2dB, i.e. at 6.4GHz.

[0080] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be defined by the appended claims.

Claims

1. A method for implementing a high-gain antenna based on a polarization-insensitive metasurface, characterized in that: The polarization-insensitive metasurface is composed of a periodic arrangement of multiple metasurface unit structures with identical structures; The metasurface unit structure includes: a dielectric substrate and a plurality of metal patches etched on one surface of the dielectric substrate; The metal patch includes four metal arms, each of which includes two strip-shaped metal patches and one semi-circular metal patch. The semi-circular metal patch is arranged such that the semi-circular metal patch connecting the tops of the two strip-shaped metal arms is rotated 90 degrees around a third direction. The strip-shaped metal patches of the four metal arms are connected to form a cross-shaped pattern; The third direction is perpendicular to the plane on which the dielectric substrate is located. The plane on which the dielectric substrate is located has a first direction and a second direction, which are set at a perpendicular angle. The third direction is the normal direction of the plane. The two strip-shaped metal patches are arranged parallel to each other and spaced apart. One end of the semi-circular metal patch is connected to one end of one of the strip-shaped metal patches, and the other end of the semi-circular metal patch is connected to one end of another strip-shaped metal patch. Two of the metal arms are parallel to the second direction, and the other two metal arms are parallel to the first direction; In the metasurface unit structure, each strip of metal patch has the same size, and each semi-circular metal patch has the same size; In a plurality of polarization-insensitive metasurfaces, multiple metasurface unit structures overlap in the third direction; in a plurality of polarization-insensitive metasurfaces, multiple metasurface unit structures are periodically arranged in the first direction and the second direction to form a periodic polarization-insensitive metasurface. The polarization-insensitive metasurface is applied as a cladding layer onto the antenna.

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