Polarization conversion metasurface

Abstract

The invention discloses a polarization conversion metasurface, which comprises a plurality of periodically arranged metasurface units, each metasurface unit comprises a plurality of dielectric plate layers and a plurality of metal layers, and the plurality of dielectric plate layers are arranged among the plurality of metal layers at intervals. Wherein the plurality of metal layers comprise a first metal layer and a second metal layer, the first metal layer is provided with a double-opening resonant ring and first metal patches located at the two sides of the double-opening resonant ring, and the second metal layer is provided with a second metal patch and third metal patches located at the two sides of the second metal patch; the third metal patch is overlapped with the boundary of the metasurface unit; and the double-opening resonant ring is provided with a metal via hole, and the metal via hole penetrates through the dielectric plate layer and is in short circuit with the second metal patch of the second metal layer, so that a resonant structure with a magnetic resonance function can be formed, broadband and wide-angular-domain polarization conversion performance is realized, and frequency selectivity is improved.

Description

Technical Field

[0001] This application relates to, but is not limited to, the field of polarization conversion metasurface design, and particularly to a polarization conversion metasurface. Background Technology

[0002] Metasurfaces are two-dimensional periodic structures composed of subwavelength units, possessing electromagnetic properties that surpass those of natural materials, enabling precise control over the amplitude, phase, and polarization state of electromagnetic waves. Applying metasurfaces to the control of electromagnetic wave polarization states can overcome the shortcomings of traditional polarizers, such as complex structures, limited functionality, and high losses.

[0003] Current research on polarization-conversion metasurfaces largely focuses on improving the operating bandwidth and optimizing the polarization conversion rate to achieve stable polarization conversion performance over a wide angular range. However, research on high frequency selectivity is still relatively lacking. In practical applications, polarization-conversion metasurfaces that combine high frequency selectivity, broadband, and wide angular range characteristics need to simultaneously achieve filtering functionality and stable polarization conversion over a wide angular range. This means maintaining stable polarization conversion performance across both broadband and wide angular ranges while effectively suppressing out-of-band signals. Therefore, developing broadband, wide angular range polarization-conversion metasurfaces with integrated high frequency selectivity has significant practical application value. Summary of the Invention

[0004] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0005] This application provides a polarization conversion metasurface that can achieve wideband, wide-angle domain polarization conversion performance and improve frequency selectivity.

[0006] This application provides a polarization conversion metasurface, comprising: a plurality of periodically arranged metasurface units, each metasurface unit comprising a plurality of dielectric slab layers and a plurality of metal layers, the plurality of dielectric slab layers being spaced apart between the plurality of metal layers; the plurality of metal layers comprising a first metal layer and a second metal layer, the first metal layer having a double-opening resonant ring and first metal patches located on both sides of the double-opening resonant ring, the second metal layer having a second metal patch and third metal patches located on both sides of the second metal patch, the third metal patches coinciding with the boundary of the metasurface unit; the double-opening resonant ring having a metal via, the metal via penetrating the dielectric slab layer and short-circuiting the second metal patch of the second metal layer to form a resonant structure with magnetic resonance function.

[0007] In one embodiment of this application, the plurality of dielectric substrate layers include a first dielectric substrate layer and a second dielectric substrate layer, and the plurality of metal layers further include a third metal layer. The first metal layer is attached to the upper surface of the first dielectric substrate layer, the second metal layer is attached between the lower surface of the first dielectric substrate layer and the upper surface of the second dielectric substrate layer, and the third metal layer is attached to the lower surface of the second dielectric substrate layer.

[0008] In one embodiment of this application, the double-opening resonant ring is located in the middle of the first metal layer, and the metal via is located on the central axis of the double-opening resonant ring.

[0009] In one embodiment of this application, the dual-slot resonant ring includes a first slot resonant ring and a second slot resonant ring arranged opposite to each other, and the openings of the first slot resonant ring and the second slot resonant ring are oriented perpendicular to the central axis of the dual-slot resonant ring.

[0010] In one embodiment of this application, the metal via includes a first via and a second via, and the first metal patch includes a first patch and a second patch, with the first patch located on one side of the first via and the second patch located on one side of the second via.

[0011] In one embodiment of this application, the second metal patch is located in the middle of the second metal layer, and the second metal patch includes a plurality of spaced patches, the plurality of spaced patches corresponding to the positions of the metal vias.

[0012] In one embodiment of this application, the second metal patch includes a third patch and a fourth patch, wherein the third patch corresponds to the position of the first via and the fourth patch corresponds to the position of the second via.

[0013] In one embodiment of this application, the diameter of the metal via is smaller than the width of the second metal patch.

[0014] In one embodiment of this application, the length of the first metal patch is the same as the longitudinal length of the double-opening resonant ring.

[0015] In one embodiment of this application, the first metal patch and the third metal patch are perpendicular to each other in their arrangement direction.

[0016] This application provides a polarization-conversion metasurface, comprising multiple periodically arranged metasurface units. Each metasurface unit includes multiple dielectric layers and multiple metal layers, with the dielectric layers spaced apart between the metal layers. The multiple metal layers include a first metal layer and a second metal layer. The first metal layer has a double-opening resonant ring and first metal patches located on both sides of the double-opening resonant ring. The second metal layer has a second metal patch and third metal patches located on both sides of the second metal patch. The third metal patches coincide with the boundary of the metasurface unit. A metal via is provided on the double-opening resonant ring, which penetrates the dielectric layer and short-circuits the second metal patches of the second metal layer, thereby forming a resonant structure with magnetic resonance function. This structure allows the polarization-conversion metasurface to achieve broadband, wide-angle polarization conversion performance, while also improving the frequency selectivity of the polarization-conversion metasurface, meeting the requirements for stable polarization conversion and effective suppression of out-of-band signals in broadband and wide-angle domains. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the unit structure of the polarization conversion metasurface provided in the embodiments of this application, wherein (a) is a front view of the first metal layer, (b) is a front view of the second metal layer, and (c) is a side view of the overall structure; Figure 2 This is a schematic diagram of the component decomposition of the electric field vector in a metasurface along the x-axis and y-axis according to a specific embodiment of this application; Figure 3 This is a schematic diagram of the reflection coefficient of a metasurface provided in a specific embodiment of this application when x and y polarized waves are incident perpendicularly; Figure 4 This is a schematic diagram of the reflection phase of a metasurface provided in a specific embodiment of this application when x and y polarized waves are incident perpendicularly; Figure 5 This is a schematic diagram of the reflection coefficient of a metasurface provided in a specific embodiment of this application when a v-polarized wave is incident perpendicularly; Figure 6 This is a schematic diagram illustrating the changes in PCR of a metasurface at different incident angles according to a specific embodiment of this application; Reference numerals: First metal layer 110; Second metal layer 120; Double-opening resonant ring 111; Third metal patch 122; Third metal layer 130; First dielectric layer 140; Second dielectric layer 150; First via 1110; Second via 1111; First patch 1120; Second patch 1121; Third patch 1210; Fourth patch 1211. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] It should be noted that although the flowchart shows a logical order, in some cases, the steps shown or described may be performed in a different order than that shown in the flowchart. The terms "first," "second," etc., used in the specification, claims, and the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the structures, proportions, sizes, etc., depicted in the drawings are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effects and purposes achieved by this application, should still fall within the scope of the technical content disclosed in this application. Similarly, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are only for clarity of description and are not used to limit the scope of implementation of this application. Changes or adjustments in their relative relationships, without substantially altering the technical content, should also be considered within the scope of implementation of this application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0021] Metasurfaces are two-dimensional periodic structures composed of subwavelength units, possessing electromagnetic properties that surpass those of natural materials, enabling precise control over the amplitude, phase, and polarization state of electromagnetic waves. Applying metasurfaces to the control of electromagnetic wave polarization can overcome the shortcomings of traditional polarizers, such as complex structures, limited functionality, and high losses.

[0022] Current research on polarization-conversion metasurfaces largely focuses on improving the operating bandwidth and optimizing the polarization conversion rate to achieve stable polarization conversion performance over a wide angular range. However, research on high frequency selectivity is still relatively lacking. In practical applications, polarization-conversion metasurfaces that combine high frequency selectivity, broadband, and wide angular range characteristics need to simultaneously achieve filtering functionality and stable polarization conversion over a wide angular range. This means maintaining stable polarization conversion performance across both broadband and wide angular ranges while effectively suppressing out-of-band signals. Therefore, developing broadband, wide angular range polarization-conversion metasurfaces with integrated high frequency selectivity has significant practical application value.

[0023] In view of this, embodiments of this application provide a polarization conversion metasurface, comprising multiple periodically arranged metasurface units. Each metasurface unit includes multiple dielectric slab layers and multiple metal layers, with the dielectric slab layers spaced apart between the metal layers. The multiple metal layers include a first metal layer and a second metal layer. The first metal layer has a double-opening resonant ring and first metal patches located on both sides of the double-opening resonant ring. The second metal layer has a second metal patch and third metal patches located on both sides of the second metal patch. The third metal patches coincide with the boundary of the metasurface unit. A metal via is provided on the double-opening resonant ring, which penetrates the dielectric slab layer and short-circuits the second metal patch of the second metal layer, thereby forming a resonant structure with magnetic resonance function. This structure allows the polarization conversion metasurface to achieve broadband, wide-angle polarization conversion performance, while improving the frequency selectivity of the polarization conversion metasurface, meeting the requirements for stable polarization conversion and effective suppression of out-of-band signals in broadband and wide-angle domains.

[0024] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0025] Reference Figure 1 , Figure 1 This is a schematic diagram of the unit structure of a polarization conversion metasurface provided in one embodiment of this application. The polarization conversion metasurface includes multiple metasurface units periodically arranged along the x and y directions. Each metasurface unit includes multiple dielectric layers and multiple metal layers, with the dielectric layers spaced apart between the metal layers. Further, the multiple metal layers include a first metal layer 110 and a second metal layer 120. The first metal layer 110 has a double-opening resonant ring 111 and first metal patches located on both sides of the double-opening resonant ring 111. The second metal layer 120 has a second metal patch and third metal patches 122 located on both sides of the second metal patch, with the third metal patches 122 coinciding with the boundary of the metasurface unit.

[0026] Furthermore, the dual-opening resonant ring 111 is provided with a metal via, which can pass through the dielectric layer and short-circuit the second metal patch of the second metal layer 120, thereby forming a resonant structure with magnetic resonance function. This structure allows the polarization conversion metasurface to achieve wideband and wide-angle domain polarization conversion performance, while improving the frequency selectivity of the polarization conversion metasurface, meeting the requirements for stable polarization conversion and effective suppression of out-of-band signals in wideband and wide-angle domains.

[0027] In one feasible embodiment, the plurality of metal layers further includes a third metal layer 130, and the plurality of dielectric layers include a first dielectric layer 140 and a second dielectric layer 150. The dielectric and metal layers are arranged in the following manner: a first metal layer 110 is attached to the upper surface of the first dielectric layer 140; a second metal layer 120 is attached between the lower surface of the first dielectric layer 140 and the upper surface of the second dielectric layer 150; and a third metal layer 130 is attached to the lower surface of the second dielectric layer 150. In this arrangement, the first metal layer 110 can be considered as a top metasurface, the second metal layer 120 as an intermediate metasurface, and the third metal layer 130 as a bottom metal floor.

[0028] In one feasible embodiment, the double-opening resonant ring 111 is located in the middle of the first metal layer 110, and the metal via is located on the central axis of the double-opening resonant ring 111.

[0029] In one feasible embodiment, the double-slit resonant ring 111 includes a first-slit resonant ring and a second-slit resonant ring disposed opposite to each other, and the openings of the first-slit resonant ring and the second-slit resonant ring are oriented perpendicular to the central axis of the double-slit resonant ring 111.

[0030] In one feasible embodiment, the metal via includes a first via 1110 and a second via 1111, and the first metal patch includes a first patch 1120 and a second patch 1121, wherein the first patch 1120 is located on one side of the first via 1110, and the second patch 1121 is located on one side of the second via 1111.

[0031] In one feasible embodiment, the second metal patch is located in the middle of the second metal layer 120. The second metal patch includes a plurality of spaced patches, which correspond to the positions of the metal vias.

[0032] In one feasible embodiment, the second metal patch includes a third patch 1210 and a fourth patch 1211, wherein the third patch 1210 corresponds to the position of the first via 1110, and the fourth patch 1211 corresponds to the position of the second via 1111.

[0033] In a specific example, the first metal layer 110 is provided with a double-slit resonant ring 111 located in the middle, and two laterally extending thin strip metal patches (i.e., patches 1120 and patches 1121) located on both sides of the double-slit resonant ring 111. The double-slit resonant ring 111 contains two back-to-back open-slit resonant rings. The open-slit resonant rings can generate a high-frequency polarization conversion zero in the high-frequency sideband. The introduction of the two thin strip metal patches can improve the polarization conversion performance under a wide incident angle. The second metal layer 120 is provided with two longitudinally extending rectangular metal patches (i.e., patches 1210 and 1211) located in the middle, and two longitudinally extending elongated metal patches (i.e., third metal patches 122) located on both sides of the two rectangular metal patches. A gap is reserved between the two rectangular metal patches, and the whole of the two rectangular metal patches coincides with the longitudinal central axis of the metasurface unit. One side of the two elongated metal patches coincides with the boundary of the metasurface unit, and their length is consistent with the period length of the metasurface unit. The introduction of this structure can form a low-frequency polarization conversion zero point. The first metal layer 110 has two metal vias (i.e., vias 1110 and 1111) in the longitudinal direction of the double-opening resonant ring 111. Both metal vias are located on the longitudinal central axis of the double-opening resonant ring 111. After penetrating the first dielectric substrate layer 140, the two metal vias are short-circuited with two rectangular metal patches in the middle of the second metal layer 120 to form a magnetic resonator. This magnetic resonator is a structure that can generate magnetic resonance effect and can complete the electromagnetic control of polarization conversion through magnetic resonance, thereby achieving wideband and wide-angle polarization conversion performance.

[0034] In one feasible embodiment, the first metal patch and the third metal patch 122 are arranged perpendicularly.

[0035] In one feasible embodiment, the length of the first metal patch is the same as the longitudinal length of the double-opening resonant ring 111.

[0036] In one feasible embodiment, the diameter of the metal via is smaller than the width of the second metal patch.

[0037] In one feasible embodiment, the polarization conversion metasurface unit arrangement period is p=6mm.

[0038] In one feasible embodiment, the first dielectric layer 140 and the second dielectric layer 150 are made of F4B board, which has a dielectric constant of 2.2 and a loss tangent of 0.001.

[0039] In one feasible embodiment, the thickness of the first dielectric layer 140 It can be set to 1.5mm, with the second dielectric layer having a thickness of 150mm. It can be set to 1.27mm.

[0040] In a feasible embodiment, the thickness t of the first, second, and third metal layers 130 can all be set to 0.035 mm.

[0041] In one feasible embodiment, such as Figure 1 As shown, the structural dimensions of the first metal layer 110 can be set as follows: a=1.1mm, b=4mm, c=2.1mm, d=2.4mm, e=0.4mm, p=6mm. The structural dimensions of the second metal layer 120 can be set as follows: f=1.1mm, g=0.9mm, i=0.4mm. The radius of the metal via can be set to 0.125mm.

[0042] In one feasible embodiment, the metal layer can be made of materials such as gold, silver, or copper, with copper being commonly chosen in practical applications. Its thickness is 0.035 mm, and its electrical conductivity is [missing information]. .

[0043] It should be understood that by generating a magnetic resonator through metal vias, the operating frequency can be adjusted by changing the position and geometry of the vias, thereby improving the miniaturization of the device and ultimately achieving wide-range stability of the metasurface's polarization conversion performance. Introducing polarization conversion zeros in the upper and lower sidebands respectively is beneficial for improving the frequency selectivity of the polarization conversion metasurface. Here, the upper sideband refers to the high-frequency operating band where the polarization conversion metasurface performs its polarization conversion function, and the lower sideband refers to the low-frequency operating band where the metasurface performs its polarization conversion function; together, they constitute the wideband operating range where the metasurface performs its polarization conversion function. Introducing polarization conversion zeros in both the high-frequency and low-frequency bands can effectively suppress out-of-band high-frequency and low-frequency interference signals, thereby improving frequency selectivity.

[0044] The beneficial effects of this application will be described in detail below with reference to specific embodiments.

[0045] In this embodiment, the following parameters were set for simulation testing: the dielectric constant of the two dielectric layers was 2.2, and the loss tangent was 0.001; all three metal layers used copper foil with a conductivity of [missing value]. The geometric parameters of the metasurface unit structure are set as follows: a=1.1mm, b=4mm, c=2.1mm, d=2.4mm, e=0.4mm, p=6mm, f=1.1mm, g=0.9mm, i=0.4mm.

[0046] To better understand the electromagnetic response of the polarization converter, this embodiment uses a v-polarized wave incident on a metasurface as an example for analysis. The electric field vector of the v-polarized wave can be decomposed into two orthogonal components along the x-axis and y-axis, such as... Figure 2 As shown.

[0047] The electric field of the incident wave is represented as: = +

[0048] in, This represents the electric field component along the x-axis of the incident electric field. This represents the electric field component along the y-axis of the incident electric field. Indicates phase.

[0049] The electric field of the reflected wave is represented as:

[0050] in, This represents the reflection coefficient along the x-axis. This represents the reflection coefficient along the y-axis. Due to the anisotropy of the metasurface, and There is a phase difference .if Furthermore, within a certain frequency range, the phase difference between the two orthogonal components When the angle is an integer multiple of 180°, the incident wave will be deflected by 90°. To study the properties of the metasurface, the amplitude and phase of the reflection coefficient of the polarization-conversion metasurface unit under perpendicular incident x and y polarized waves were simulated using CST simulation software. The results are as follows: Figure 3 and 4 As shown. Figure 3 The results show that the polarization conversion metasurface unit operates in the range of 10.61–19.48 GHz. On the other hand, from Figure 4 It can be observed that the phase difference between the two orthogonal components within the same frequency band is approximately 180°. Therefore, it can be concluded that this polarization-conversion metasurface unit can achieve cross-polarization conversion in the range of 10.61-19.48 GHz.

[0051] For reflective cross-polarization converters, polarization conversion efficiency (PCR) is an important performance indicator, which can be expressed as:

[0052] in, Indicates the cross-polarization reflection coefficient. This represents the same-polarization reflection coefficient. Cross-polarization reflection coefficient. Copolarized reflection coefficient .when , When PCR = 1, the polarization conversion effect is optimal. Full-wave simulation of the polarization-converting metasurface unit under perpendicular incidence of a v-polarized wave was performed using CST software, and the reflection coefficients were obtained as follows: Figure 5As shown, zero point 1 is the low-frequency polarization conversion zero, and zero point 2 is the high-frequency polarization conversion zero. It can be seen that the polarization-converting metasurface generates two resonant frequencies under perpendicular incidence of a v-polarized wave: 11.7 GHz and 18.86 GHz. This dual-resonance characteristic extends the cross-polarization reflection bandwidth. From the above polarization conversion rate expression, it can be concluded that the polarization conversion rate of this polarization-converting metasurface is greater than 90% in the 10.61-19.48 GHz range, with a relative bandwidth of 58.95%.

[0053] Furthermore, for filter-type polarization converters, frequency selectivity is an important indicator of their filtering performance, which can be expressed as:

[0054] in, The amplitude value of the cross-polarization reflection coefficient at zero point is represented. This represents the amplitude value of the cross-polarization reflection coefficient at -3dB. for The corresponding frequency, for The corresponding frequency, Here, LFS and UFS represent the lower sideband frequency selectivity and upper sideband frequency selectivity, respectively, with a larger calculated L(U)FS value indicating better frequency selectivity. Figure 5 It can be calculated that the frequency selectivity of the LFS and UFS of this polarization conversion metasurface is 616 and 966, respectively, indicating that the display device has excellent frequency selectivity.

[0055] In this embodiment, to study the polarization conversion and filtering performance of the polarization conversion metasurface under wide incident angles, the reflectance coefficient and PCR of the metasurface at different incident angles were simulated. The results are as follows: Figure 6 As shown in the figure, under perpendicular incidence, the co-polarization reflectance is less than -10 dB in the range of 10.61–19.48 GHz, and the PCR is greater than 0.9, with a relative bandwidth of 58.95% and frequency selectivity of 616 and 966. At an incidence angle of 45°, the co-polarization reflectance is less than -10 dB in the range of 10.41–19.41 GHz, the PCR is greater than 0.9, and the relative bandwidth is 60.36%. Compared to the perpendicular incidence case, the 90% PCR bandwidth changed by 1.41% under 45° oblique incidence, while the frequency selectivity remained essentially unchanged, indicating that the device has excellent wide-angle stability.

[0056] Simulation results verify that this polarization conversion metasurface maintains stable high polarization conversion performance and high frequency selectivity across a wide bandwidth and wide angle range. The specific benefits are as follows: it enables the integration of cross-polarization conversion and high frequency selectivity across a wide bandwidth; it exhibits wide-angle stability, with the polarization conversion bandwidth changing by only 1.41% within an incident angle range of 0-45°, achieving a 90% polarization conversion rate, while maintaining stable frequency selectivity in both the upper and lower sidebands; and its overall structure is simple and compact, easy to fabricate, and readily integrated with other devices.

[0057] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A polarization conversion metasurface, characterized in that, The device comprises multiple periodically arranged metasurface units, each metasurface unit including multiple dielectric layers and multiple metal layers, the dielectric layers being spaced apart between the metal layers; the multiple metal layers include a first metal layer and a second metal layer, the first metal layer having a double-opening resonant ring and first metal patches located on both sides of the double-opening resonant ring, the second metal layer having a second metal patch and third metal patches located on both sides of the second metal patch, the third metal patches coinciding with the boundary of the metasurface unit; the double-opening resonant ring having metal vias, the metal vias penetrating the dielectric layer and short-circuiting the second metal patches of the second metal layer to form a resonant structure with magnetic resonance function.

2. The polarization conversion metasurface according to claim 1, characterized in that, The plurality of dielectric substrate layers include a first dielectric substrate layer and a second dielectric substrate layer, and the plurality of metal layers further include a third metal layer. The first metal layer is attached to the upper surface of the first dielectric substrate layer, the second metal layer is attached between the lower surface of the first dielectric substrate layer and the upper surface of the second dielectric substrate layer, and the third metal layer is attached to the lower surface of the second dielectric substrate layer.

3. The polarization conversion metasurface according to claim 1, characterized in that, The double-opening resonant ring is located in the middle of the first metal layer, and the metal via is located on the central axis of the double-opening resonant ring.

4. The polarization conversion metasurface according to claim 1, characterized in that, The dual-slot resonant ring includes a first slot resonant ring and a second slot resonant ring arranged opposite to each other, and the openings of the first slot resonant ring and the second slot resonant ring are perpendicular to the central axis of the dual-slot resonant ring.

5. The polarization conversion metasurface according to claim 4, characterized in that, The metal via includes a first via and a second via, and the first metal patch includes a first patch and a second patch, with the first patch located on one side of the first via and the second patch located on one side of the second via.

6. The polarization conversion metasurface according to claim 1, characterized in that, The second metal patch is located in the middle of the second metal layer. The second metal patch includes a plurality of spaced patches, and the spaced patches correspond to the positions of the metal vias.

7. The polarization conversion metasurface according to claim 5, characterized in that, The second metal patch includes a third patch and a fourth patch, wherein the third patch corresponds to the position of the first via and the fourth patch corresponds to the position of the second via.

8. The polarization conversion metasurface according to claim 1, characterized in that, The diameter of the metal via is smaller than the width of the second metal patch.

9. The polarization conversion metasurface according to claim 1, characterized in that, The length of the first metal patch is the same as the longitudinal length of the double-opening resonant ring.

10. The polarization conversion metasurface according to claim 1, characterized in that, The first metal patch and the third metal patch are perpendicular to each other in their orientation.

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