A dual-wideband high-symmetry polarization conversion metasurface

Abstract

This invention relates to a dual-broadband high-symmetry polarization conversion metasurface, comprising a plurality of subwavelength units arranged periodically along a two-dimensional plane. Each subwavelength unit includes a dielectric substrate, a metal pattern layer, and a reflective layer. The surface profile of the dielectric substrate is square. The metal pattern layer is disposed on the front side of the dielectric substrate and includes a resonant ring portion and a central resonant portion. The resonant ring portion is a square ring structure, with openings formed at the midpoints of its upper and left straight edges, while the other two straight edges do not form openings. The extension direction of the openings is perpendicular to the corresponding straight edges. The central resonant portion includes two metal straight segments connected to form a cross-shaped structure, with the length directions of the two metal straight segments correspondingly pointing to the two openings. The reflective layer is a metal layer covering the back side of the dielectric substrate. The center-to-center distance between adjacent subwavelength units is equal to the side length of the front side of the dielectric substrate.

Description

Technical Field

[0001] This invention relates to the technical field of antenna devices, and more particularly to a dual-broadband high-symmetry polarization conversion metasurface. Background Technology

[0002] In the field of microwave polarization modulation, polarization conversion technology is the core means to achieve flexible control of electromagnetic wave polarization states. Existing technologies are mainly divided into two categories: One type is the traditional polarization control scheme, which mainly relies on the inherent optical properties of the crystal or the effect of a magnetic field to achieve polarization conversion. This type of scheme controls the polarization state of electromagnetic waves through the optical properties of the crystal itself or an external magnetic field, and is a classic method of polarization conversion. However, products using this type of scheme are bulky, far exceeding the installation threshold of portable devices, and their operating bandwidth is concentrated in a single frequency band, making it difficult to simultaneously cover the mid-to-high frequency bands of 5G and the high frequency candidate bands of 6G. In addition, they are susceptible to electromagnetic interference from adjacent devices in densely deployed scenarios such as base stations, which greatly limits their overall practicality.

[0003] Another type is the metasurface-based polarization conversion scheme, which achieves polarization conversion by designing metasurfaces with orthogonal polarization differential responses or chiral structures. Some of these schemes can achieve high polarization conversion efficiency or polarization conversion functionality within specific frequency bands, but they still have the following limitations: High-performance polarization conversion metasurfaces often employ multi-layer structures with four or more layers, requiring micron-level alignment accuracy between layers, resulting in complex photolithography processes, low yields, and higher production costs compared to single-layer structures, making it difficult to adapt to the large-scale deployment requirements of base station antennas; Most schemes can only operate in a single frequency band, and a single resonant structure cannot cover the dual broadband requirements of 5G mid-high frequency and 6G high frequency candidate bands, and the high-frequency response attenuation is severe, often requiring multiple metasurfaces to be combined, increasing the device size; The edge effect of the unit array is significant, and when the center-to-center distance between adjacent units is too small, the polarization conversion purity drops significantly, failing to meet the requirements of narrow-pitch integration; Some schemes lack symmetry design, resulting in excessively high fluctuations in conversion efficiency when X / Y polarized incident, affecting the stability of communication signals.

[0004] In summary, existing technologies are clearly insufficient in adapting to the development trends of modern communication equipment, such as "ultra-narrow bezels, cross-frequency bands (5G+6G), low cost, high stability, and miniaturization". Summary of the Invention

[0005] The purpose of this invention is to provide a dual-broadband high-symmetry polarization conversion metasurface, which has the advantages of low manufacturing cost, high efficiency of cross-polarization conversion in dual broadband frequency bands, and strong signal anti-interference ability.

[0006] The technical solution adopted in this invention is: a dual-bandwidth high-symmetry polarization conversion metasurface, comprising a plurality of subwavelength units arranged periodically along a two-dimensional plane; each subwavelength unit includes a dielectric substrate, a metal pattern layer, and a reflective layer; the surface profile of the dielectric substrate is square; the metal pattern layer is disposed on the front side of the dielectric substrate, and the metal pattern layer includes a resonant ring portion and a central resonant portion; the resonant ring portion is a square ring structure, and the resonant ring portion is disposed around the center of the front side of the dielectric substrate, with the four straight sides of the resonant ring portion corresponding to and parallel to the four side edges of the front side of the dielectric substrate, the side length of the resonant ring portion being smaller than the side length of the dielectric substrate, and the middle of the upper straight side and the left straight side of the resonant ring portion on the two-dimensional plane. All positions are cut to form openings and gaps, while the other two straight edges do not form openings and gaps. The extension direction of the openings and gaps is perpendicular to the corresponding straight edges. The width of the straight edges of the resonant ring is equal to the width of the openings and gaps. The central resonant part includes two metal straight segments. The two metal straight segments are perpendicular to each other and their center points are connected to form a cross-shaped structure. The connection point between the two metal straight segments is located at the center of the resonant ring. The length directions of the two metal straight segments point one-to-one to the two openings and gaps of the resonant ring. The width of the metal straight segments is smaller than the width of the openings and gaps. The reflective layer is a metal layer covering the back of the dielectric substrate. The center-to-center spacing of adjacent subwavelength units in the two-dimensional arrangement direction is the side length of the front side of the dielectric substrate.

[0007] The working principle of this invention is as follows: This metasurface operates in dual broadband bands: 6.55 GHz to 12.4 GHz and 15.2 GHz to 23 GHz. The metal patterned layer of the subwavelength unit, through the synergistic effect of the resonant ring and the central resonant section, ensures highly consistent responses for X-polarized and Y-polarized incident waves, resulting in low conversion efficiency and phase fluctuations, significantly improving polarization purity and communication signal stability. The dielectric substrate of the subwavelength unit provides physical support and electromagnetic isolation for the metal patterned layer. The reflective layer of the subwavelength unit provides fundamental constraints for polarization conversion, ensuring that the incident electromagnetic wave, after being modulated by the metal patterned layer, is reflected and output in a cross-polarized form, avoiding transmission energy loss. The subwavelength unit employs a three-layer structure of a metal patterned layer, a dielectric substrate, and a reflective layer. With a low total thickness, it eliminates the need for complex multi-layer alignment and can be fabricated using conventional photolithography and etching processes. This simple fabrication process offers high yield, low cost, and facilitates mass production and practical engineering applications. The subwavelength units are arranged periodically along a two-dimensional plane, with the center-to-center spacing of adjacent subwavelength units in the two-dimensional arrangement direction consistent with the overall side length of the subwavelength unit, forming a compact and uniform array structure. This periodic structure design ensures the consistency and stability of the overall electromagnetic response of the metasurface, effectively avoiding the interference of edge effects on polarization conversion performance, and providing a structural basis for realizing dual-broadband cross-polarization conversion functionality. This design results in low fabrication cost, high cross-polarization conversion performance, and strong signal anti-interference capability of this metasurface, meeting the application requirements of 5G / 6G multi-band communication.

[0008] Furthermore, in the aforementioned dual-broadband high-symmetry polarization conversion metasurface, the width of the straight side of the resonant ring is 1 / 6 of the length of the outer ring side of the resonant ring.

[0009] Furthermore, in the aforementioned dual-broadband high-symmetry polarization conversion metasurface, the width of the metal straight segment of the central resonant portion is 1 / 6 of its length.

[0010] Furthermore, in the aforementioned dual-broadband high-symmetry polarization conversion metasurface, the length of the straight metal segment of the central resonant section is half the length of the outer ring side of the resonant ring section.

[0011] Furthermore, in the aforementioned dual-broadband high-symmetry polarization conversion metasurface, the distance between the straight edge of the resonant ring and the side edge of the adjacent dielectric substrate front side is 1 / 2 the width of the straight edge of the resonant ring.

[0012] Furthermore, in the aforementioned dual-broadband high-symmetry polarization conversion metasurface, the side length of the front side of the dielectric substrate is in the range of 4mm to 6.5mm.

[0013] Furthermore, in the aforementioned dual-broadband high-symmetry polarization conversion metasurface, the thickness of the dielectric substrate is in the range of 1.8 mm to 2 mm.

[0014] The beneficial effects of this invention include: low manufacturing cost, high cross-polarization conversion performance, strong signal anti-interference capability, and the ability to meet the application requirements of 5G / 6G multi-band communication. Attached Figure Description

[0015] Figure 1 This is the main view of the embodiment; Figure 2 This is a front view of the subwavelength unit in the embodiment; Figure 3 Rear view of the subwavelength unit in the embodiment; Figure 4 Right view of the subwavelength unit in the embodiment; Figure 5 The cross-polarization reflection coefficient results are shown in the example diagram; Figure 6 The following is a diagram showing the common polarization reflection coefficient results for an example. Figure 7 The diagram shows the results of cross-polarization and co-polarization reflection coefficients for X-polarized incident light in the example. Figure 8 The diagram shows the results of cross-polarization and co-polarization reflection coefficients for Y-polarized incident light in the example. Figure 9 The polarization conversion ratio result is shown in the example diagram.

[0016] Explanation of reference numerals in the attached figures: 1-Subwavelength unit; 11-Dielectric substrate; 12-Metal pattern layer; 121-Resonant ring; 1211-Opening gap; 122-Central resonant part; 1221-Metal straight line segment; 13-Reflective layer. Detailed Implementation

[0017] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0018] like Figures 1 to 4An embodiment of a dual-bandwidth high-symmetry polarization conversion metasurface includes a plurality of subwavelength units 1, which are periodically arranged along a two-dimensional plane. Each subwavelength unit 1 includes a dielectric substrate 11, a metal pattern layer 12, and a reflective layer 13. The dielectric substrate 11 is made of FR4 material, has a square surface profile, a side length D1 of 5.6 mm on the front side, and a thickness D2 of 1.92 mm. The metal pattern layer 12 is disposed on the front side of the dielectric substrate 11 and includes... The resonant ring 121 and the central resonant part 122 are included. The resonant ring 121 has a square ring structure and is arranged around the center of the front side of the dielectric substrate 11. The four straight sides of the resonant ring 121 correspond to the four side sides of the front side of the dielectric substrate 11 and are close to and parallel to each other. The outer ring side length D3 of the resonant ring 121 is 4.8 mm, the width D4 of the straight sides of the resonant ring 121 is 0.8 mm, and the distance D5 between the straight sides of the resonant ring 121 and the adjacent side sides of the front side of the dielectric substrate 11 is 0.4 mm. The upper and left straight edges of part 121 are each cut at the middle position to form an opening slit 1211. The other two straight edges do not form opening slits 1211. The extension direction of the opening slits 1211 is perpendicular to the corresponding straight edge, and the slit width D6 of the opening slits 1211 is 0.8 mm. The central resonant part 122 includes two metal straight segments 1221. The two metal straight segments 1221 are perpendicular to each other and their center points are connected to form a cross-shaped structure. The connection point between the two metal straight segments 1221 is at a resonant position. The resonant ring 121 is surrounded by two metal straight segments 1221 whose lengths correspond one-to-one with the two openings 1211 of the resonant ring 121. The length D7 of the metal straight segment 1221 is 2.4 mm and the width D8 of the metal straight segment 1221 is 0.4 mm. The reflective layer 13 is a metal layer covering the back of the dielectric substrate 11. The metal pattern layer 12 and the reflective layer 13 are both copper-clad layers with a thickness D9 of 0.028 mm. The center-to-center spacing D10 of the adjacent subwavelength units 1 in the two-dimensional arrangement direction is 5.6 mm.

[0019] This metasurface operates in dual broadband bands: 6.55 GHz to 12.4 GHz and 15.2 GHz to 23 GHz. The metal patterned layer 12 of the subwavelength unit 1, through the synergistic effect of the resonant ring 121 and the central resonant section 122, ensures highly consistent responses for X-polarized and Y-polarized incident waves, resulting in low conversion efficiency and phase fluctuations, significantly improving polarization purity and communication signal stability. The dielectric substrate 11 of the subwavelength unit 1 provides physical support and electromagnetic isolation for the metal patterned layer 12, with a thickness of 1.92 mm. This design parameter ensures both structural mechanical strength and reduces electromagnetic energy loss, guaranteeing polarization conversion efficiency. The reflective layer 13 of the subwavelength unit 1 provides fundamental constraints for polarization conversion, ensuring that the incident electromagnetic wave, after being modulated by the metal patterned layer 12, is reflected and output in a cross-polarized form, avoiding transmission energy loss. The subwavelength unit 1 adopts a three-layer structure consisting of a metal patterned layer 12, a dielectric substrate 11, and a reflective layer 13. This structure has a low total thickness, eliminates the need for complex multi-layer alignment, and can be fabricated using conventional photolithography and etching processes. The fabrication process is simple, yields high efficiency, and is low-cost, facilitating mass production and practical engineering applications. Each subwavelength unit 1 is arranged periodically along a two-dimensional plane, with a center-to-center spacing of 5.6 mm between adjacent subwavelength units 1 in the two-dimensional arrangement direction, consistent with the overall side length of the subwavelength unit 1, forming a compact and uniform array structure. This periodic structure design ensures the consistency and stability of the overall electromagnetic response of the metasurface, effectively avoiding the interference of edge effects on polarization conversion performance, and providing a structural foundation for the realization of dual-broadband cross-polarization conversion functionality. This design results in low fabrication cost, high cross-polarization conversion performance, and strong signal anti-interference capability for this metasurface, meeting the application requirements of 5G / 6G multi-band communication.

[0020] Through the above design, the metasurface can be tested to obtain the following results: Figure 5 The cross-polarization reflection coefficient results are shown in the figure below. Figure 6 The diagram showing the co-polarization reflection coefficient results is as follows: Figure 7 The diagram shows the results of cross-polarization and co-polarization reflection coefficients for X-polarized incident light. Figure 8 The results of cross-polarization and co-polarization reflection coefficients for Y-polarized incident light are shown in the figure. Figure 9 The polarization conversion ratio results are shown in the figure.

[0021] Depend on Figure 5It can be seen that within the dual broadband bands of 6.55GHz–12.4GHz and 15.2GHz–23GHz, the cross-polarization reflection coefficient amplitude is greater than -3dB, meeting the core requirement for high-efficiency conversion. At the four resonant frequencies of 6.87GHz, 10.2GHz, 17.9GHz, and 22.35GHz, the reflection coefficient is less than -2dB, achieving peak conversion efficiency. Therefore, this metasurface exhibits high-efficiency cross-polarization conversion performance within the dual broadband bands of 6.55GHz–12.4GHz and 15.2GHz–23GHz, meeting the application requirements of 5G / 6G multi-band communication.

[0022] Depend on Figure 6 It can be seen that within the dual broadband bands of 6.55GHz to 12.4GHz and 15.2GHz to 23GHz, the overall amplitude of the common polarization reflection coefficient is relatively small. Specifically, it drops to -18dB to -25dB at the resonant frequencies of 6.87GHz, 10.2GHz, 17.9GHz, and 22.35GHz, indicating that the common polarization component is significantly suppressed and the polarization conversion purity is high. This effectively avoids common polarization interference, especially in the high-frequency band, maintaining a low common polarization reflection coefficient and ensuring the anti-interference capability of 6G high-frequency communication signals.

[0023] Depend on Figure 7 and Figure 8 It can be seen that the S-parameter curves of X-polarized incident and Y-polarized incident are highly coincident, verifying the good polarization symmetry of the metasurface; the changing trends of the cross-polarization reflection coefficient and the co-polarization reflection coefficient under the two polarization incident are completely consistent, proving that stable cross-polarization conversion can be achieved for incident in different polarization directions, and excellent symmetry is maintained even in the 23GHz high-frequency band, solving the problem of symmetry attenuation in the high-frequency band of existing technologies.

[0024] Depend on Figure 9 It can be seen that the polarization conversion ratio (PCR) values ​​at resonant frequencies of 6.87 GHz, 10.2 GHz, 17.9 GHz, and 22.35 GHz are close to 1, achieving near-perfect polarization conversion. The PCR is greater than 60% in the 6.55 GHz–12.4 GHz broadband band and greater than 75% in the 15.2 GHz–23 GHz broadband band, verifying the high efficiency and stability of the metasurface over a wide frequency range. Furthermore, the PCR performance in the high-frequency band is superior to that in the low-frequency band, further ensuring the stability and reliability of polarization conversion in 6G high-frequency communication.

[0025] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications, combinations, and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A dual-broadband high-symmetry polarization conversion metasurface, characterized in that: It includes several subwavelength units arranged periodically along a two-dimensional plane; each subwavelength unit includes a dielectric substrate, a metal pattern layer, and a reflective layer; the surface profile of the dielectric substrate is square; the metal pattern layer is disposed on the front side of the dielectric substrate, and includes a resonant ring and a central resonant portion; the resonant ring is a square ring structure, arranged around the center of the front side of the dielectric substrate, with its four straight edges corresponding to and parallel to the four side edges of the front side of the dielectric substrate, and the side length of the resonant ring being smaller than the side length of the dielectric substrate; the upper straight edge of the resonant ring on the two-dimensional plane... Each of the left straight edges is cut open at its midpoint to form an opening slit. The other two straight edges do not form opening slits. The extension direction of the opening slits is perpendicular to the corresponding straight edge. The width of the straight edge of the resonant ring and the width of the opening slit are equal. The central resonant part includes two metal straight segments. The two metal straight segments are perpendicular to each other and their center points are connected to form a cross-shaped structure. The connection point between the two metal straight segments is located at the center of the resonant ring. The length directions of the two metal straight segments point one-to-one to the two opening slits of the resonant ring. The width of the metal straight segments is smaller than the width of the opening slits. The reflective layer is a metal layer covering the back of the dielectric substrate; The center-to-center spacing of adjacent subwavelength units in the two-dimensional arrangement direction is the side length of the front side of the dielectric substrate.

2. The dual broadband high-symmetry polarization conversion metasurface as described in claim 1, characterized in that: The width of the straight side of the resonant ring is 1 / 6 of the length of the outer ring side of the resonant ring.

3. The dual-broadband high-symmetry polarization conversion metasurface as described in claim 1, characterized in that: The width of the straight metal segment of the central resonant part is 1 / 6 of its length.

4. The dual broadband high-symmetry polarization conversion metasurface as described in claim 1, characterized in that: The length of the straight metal segment of the central resonant part is 1 / 2 of the length of the outer ring of the resonant ring part.

5. The dual-broadband high-symmetry polarization conversion metasurface as described in claim 1, characterized in that: The distance between the straight edge of the resonant ring and the side edge of the adjacent dielectric substrate is half the width of the straight edge of the resonant ring.

6. The dual broadband high-symmetry polarization conversion metasurface as described in claim 1, characterized in that: The side length of the front side of the dielectric substrate is in the range of 4mm to 6.5mm.

7. The dual-broadband high-symmetry polarization conversion metasurface as described in claim 1, characterized in that: The thickness of the dielectric substrate is in the range of 1.8 mm to 2 mm.

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