Ultra-wideband linear-to-circular polarization converter based on wheel-shaped metasurface
By designing a wheel-shaped metasurface structure, the problem of insufficient bandwidth and angular stability in existing linear-to-circular polarization converters is solved, realizing ultra-wideband, high-angle-stable linear-to-circular polarization wave conversion, with the advantages of low cost and easy processing.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NANJING UNIV OF POSTS & TELECOMM
- Filing Date
- 2025-09-22
- Publication Date
- 2026-06-18
Smart Images
Figure CN2025122866_18062026_PF_FP_ABST
Abstract
Description
An ultrawideband linear circular polarization converter based on a wheel-shaped metasurface Technical Field
[0001] This application belongs to the field of microwave technology, specifically relating to an ultrawideband linear circular polarization converter based on a wheel-shaped metasurface. Background Technology
[0002] Electromagnetic wave manipulation technology, especially electromagnetic wave polarization manipulation, has always been a key research focus in the field of electromagnetic propagation. Common electromagnetic wave polarization forms include linear polarization, circular polarization, and elliptical polarization, each with its unique advantages and practical value in specific application scenarios. Taking circularly polarized waves as an example, their anti-interference capability in complex electromagnetic environments is particularly significant: in satellite communication scenarios, signal reflection from the ionosphere easily induces multipath effects, and circularly polarized waves, with their rotational characteristics, can effectively suppress interference from reflected signals; in 5G base station communication, circularly polarized waves can mitigate signal fading caused by environmental factors such as rain and fog, thus ensuring the stability and reliability of information transmission in environments with strong interference, making it a key factor in improving the performance of modern communication systems. As a core device for realizing circularly polarized waves, linear-to-circular polarization converters have broad application potential in microwave communication, microscopic imaging, broadcasting, and other fields.
[0003] Early traditional polarization converters relied primarily on the optical rotation effect of natural materials to control the polarization of electromagnetic waves. However, these converters generally suffered from narrow bandwidth, poor angular stability, large size, and low integration, severely limiting their application in practical scenarios. In contrast, metasurface polarization converters, through precise design of unit structures, can efficiently control the phase and polarization characteristics of electromagnetic waves, exhibiting unique electromagnetic response characteristics such as anisotropy and anomalous reflection / transmission. Furthermore, these converters offer significant advantages such as small size, thinness, light weight, low loss, and ease of integration with other components, making them an ideal solution to overcome the shortcomings of traditional polarization converters.
[0004] Despite some progress in the research of metasurface polarization converters, their large-scale application still faces multiple challenges: First, existing converters are mostly designed for single frequency bands, such as the Ku band from 12GHz to 18GHz, which cannot meet the full coverage requirements of the C / Ku / K bands (4GHz to 27GHz), resulting in bandwidth limitations. Second, existing metasurface polarization converters suffer from insufficient angular stability; as the incident angle increases, the axial ratio deteriorates significantly, limiting their application in wide-angle scanning scenarios such as phased array radar. Third, manufacturing costs are a key factor restricting the industrialization of metasurface technology, especially since subwavelength metal patterns require processing accuracy of ±5μm, and high-performance dielectric substrates are expensive. Therefore, developing wide-bandwidth, high-angular-stability, and low-cost linear-circular polarization converters is of significant practical importance. Summary of the Invention
[0005] To address the technical limitations of existing linear-to-circular polarization converters in terms of bandwidth expansion, angular stability, and fabrication complexity, this application proposes an ultrawideband linear-to-circular polarization converter based on a wheel-shaped metasurface. This application successfully achieves efficient conversion of linearly polarized waves to circularly polarized waves through the innovative design of a wheel-shaped metal pattern. While significantly improving the operating bandwidth and angular stability, it retains the core advantages of simple structure and convenient fabrication, possessing both significant theoretical research value and engineering application potential.
[0006] To achieve the above objectives, this application employs the following technical solution:
[0007] This application relates to an ultrawideband linear circular polarization converter based on a wheel-shaped metasurface.
[0008] This application discloses an ultrawideband linear-to-circular polarization converter based on a wheel-shaped metasurface. The ultrawideband linear-to-circular polarization converter based on the wheel-shaped metasurface consists of periodically arranged reflective polarization conversion units, each of which adopts a stacked structure. Each reflective polarization conversion unit includes an upper wheel-shaped metal pattern layer, an intermediate dielectric substrate, and a bottom metal layer. The upper surface of the intermediate dielectric substrate is tightly connected to the upper wheel-shaped metal pattern layer, and the lower surface of the intermediate dielectric substrate is tightly connected to the bottom metal layer. The upper wheel-shaped metal pattern layer, the intermediate dielectric substrate, and the bottom metal layer work together to achieve polarization modulation. Specifically, when a linearly polarized wave is incident on the polarization converter, the upper wheel-shaped metal pattern layer converts the incident linearly polarized wave into a circularly polarized wave; the intermediate dielectric substrate extends the transmission path of the linearly polarized wave, generating resonance; and the bottom metal layer reflects the incident linearly polarized wave.
[0009] A further improvement of this application is that: the upper wheel-shaped metal pattern layer has a wheel-shaped structure, composed of cross-shaped metal sheets, circular metal sheets, and rectangular metal strips. The cross-shaped metal sheets are symmetrically distributed along the diagonal direction with the center of the surface of the reflective polarization conversion unit as the symmetry point. The cross-shaped metal sheets include orthogonal metal sheets along the long axis and metal sheets along the short axis. The metal sheets along the short axis are perpendicularly overlapped at the center point of the surface of the reflective polarization conversion unit. Two circular metal sheets are symmetrically arranged at the ends of the metal sheets along the long axis. The center of each circular metal sheet is located on the diagonal. Each circular metal sheet has six rectangular metal strips of the same size. Each rectangular metal strip is rotationally symmetrically distributed with the center of the circular metal sheet at 30° equidistant angles.
[0010] A further improvement of this application is that: the length L1 of the metal sheet along the major axis is 6.2 mm and the width W1 is 0.3 mm; the length L2 of the metal sheet along the minor axis is 0.8 mm and the width W2 is 0.4 mm; the distance between the center of the circular metal sheet and the center of the surface of the reflective polarization conversion unit is 3.1 mm; the diameter D of each circular metal sheet is 1.6 mm; and the length L3 of each rectangular metal strip is 2 mm and the width W3 is 0.3 mm.
[0011] A further improvement of this application is that the intermediate dielectric substrate is selected with a relative permittivity ε. r =4.3, FR4 dielectric material with loss tangent tanδ = 0.025, wherein the dimensions of the intermediate dielectric substrate are length × width × thickness = 8.2mm × 8.2mm × 2.4mm.
[0012] A further improvement of this application is that: both the upper wheel-shaped metal pattern layer and the bottom metal layer are made of copper material and the upper wheel-shaped metal pattern layer and the bottom metal layer have the same thickness, which is 0.035 mm.
[0013] A further improvement of this application is that the side length p of the reflective polarization conversion unit is 8.2 mm.
[0014] The beneficial effects of this application are: (1) This application utilizes a unique wheel-shaped metal pattern to successfully achieve efficient conversion of linearly polarized waves to circularly polarized waves. (2) Within the frequency range of 7.05 GHz to 18.91 GHz, this application can convert vertically incident linearly polarized waves into circularly polarized waves with a 3dB axial ratio bandwidth of 91.37%, exhibiting ultra-wide bandwidth characteristics. (3) When the incident angle is 40°, the bandwidth of the converter can be maintained within 7.05 to 15.34 GHz, with a 3dB axial ratio bandwidth of 74.05%, exhibiting good angular stability. (4) The phase difference of the reflected electromagnetic wave electric vector components is stable, and the amplitudes of the two components are almost equal. (5) This invention has a simple structure and small size, specifically 0.355λ × 0.355λ × 0.104λ. (6) This application uses a single-layer FR4 dielectric substrate with a low profile, making it easy to manufacture and producing, and thus having a lower production cost. Attached Figure Description
[0015] Figure 1 is a three-dimensional structural schematic diagram of the ultrawideband linear circular polarization converter unit structure of this application.
[0016] Figure 2 is a dimensional diagram of the ultrawideband line-circular polarization converter unit structure of this application.
[0017] Figure 3 shows the amplitude and phase difference of the reflection coefficient when the y-polarized wave is incident perpendicularly in the ultrawideband linear circular polarization converter of this application.
[0018] Figure 4 is a 3dB axial ratio diagram of the y-polarized wave in the ultrawideband linear circular polarization converter of this application when the incident angle is 0°, 20° and 40°.
[0019] Figure 5 shows the reflection coefficient amplitudes of u-polarized and v-polarized waves incident on the ultrawideband linear circular polarization converter of this application.
[0020] Figure 6 is a diagram showing the reflection coefficient phase and phase difference of the ultrawideband line-circular polarization converter of this application when u-polarized waves and v-polarized waves are incident.
[0021] Among them, 1-upper wheel-shaped metal pattern layer; 2-middle dielectric substrate; 3-bottom metal layer. Detailed Implementation
[0022] The embodiments of the present invention will be disclosed below with reference to the drawings. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the present invention. That is, in some embodiments of the present invention, these practical details are not essential. In addition, for the sake of simplicity, some conventional structures and components will be shown in the drawings in a simple schematic manner.
[0023] As shown in Figures 1-2, this application discloses an ultrawideband linear circular polarization converter based on a wheel-shaped metasurface, wherein the side length p of the reflective polarization conversion unit is 8.2 mm. The ultrawideband linear circular polarization converter based on the wheel-shaped metasurface consists of periodically arranged reflective polarization conversion units, each employing a stacked structure. Each reflective polarization conversion unit includes an upper wheel-shaped metal pattern layer 1, an intermediate dielectric substrate 2, and a bottom metal layer 3. The upper surface of the intermediate dielectric substrate 2 is tightly connected to the upper wheel-shaped metal pattern layer 1, and the lower surface of the intermediate dielectric substrate 2 is tightly bonded to the bottom metal layer 3.
[0024] The upper wheel-shaped metal pattern layer 1, the intermediate dielectric substrate 2, and the bottom metal layer 3 work together to achieve ultra-wideband, high-angle-stability polarization control. Specifically, when a linearly polarized wave is incident on the polarization converter, the upper wheel-shaped metal pattern layer 1 decomposes the incident linearly polarized wave into two orthogonal polarization components, introducing a 90° phase difference to achieve the conversion from linearly polarized wave to circularly polarized wave. The intermediate dielectric substrate 2 extends the transmission path of the linearly polarized wave through dielectric modulation to generate resonance. The bottom metal layer 3 is used to reflect the incident linearly polarized wave.
[0025] The upper wheel-shaped metal pattern layer 1 is made of copper with a thickness of 0.035mm. The upper wheel-shaped metal pattern layer 1 has a wheel-shaped structure and is composed of cross-shaped metal sheets, circular metal sheets and rectangular metal strips. The cross-shaped metal sheets are symmetrically distributed along the diagonal direction with the center of the reflective polarization conversion unit surface as the symmetrical point. Each cross-shaped metal sheet includes orthogonal metal sheets along the major and minor axes. The length L1 of the major axis metal sheet is 6.2 mm, and the width W1 is 0.3 mm. The minor axis metal sheets are perpendicularly overlapped at the center point of the reflective polarization conversion unit surface, with a length L2 of 0.8 mm and a width W2 of 0.4 mm. Two circular metal sheets are symmetrically arranged at the ends of the major axis metal sheets. The distance between the center of each circular metal sheet and the center of the reflective polarization conversion unit surface is 3.1 mm. The center of each circular metal sheet is located on the diagonal, and the diameter D of each circular metal sheet is 1.6 mm. Each circular metal sheet has six identical rectangular metal strips, each with a length L3 of 2 mm and a width W3 of 0.3 mm. Each rectangular metal strip is rotationally symmetrically distributed at 30° intervals around the center of the circular metal sheet.
[0026] The intermediate dielectric substrate 2 is selected with a relative permittivity ε r =4.3, FR4 dielectric material with loss tangent tanδ = 0.025, which is inexpensive and easy to process. The dimensions of the intermediate dielectric substrate 2 are length × width × thickness = 8.2mm × 8.2mm × 2.4mm.
[0027] The bottom metal layer 3 is a complete metal panel, closely attached to the lower surface of the intermediate dielectric substrate 2, used to reflect incident radiopolarized waves. This bottom metal layer 3 is made of copper material with a thickness of 0.035 mm. This thickness is the standard PCB copper foil thickness, conforming to industrial processing specifications and facilitating mass production.
[0028] Due to the symmetry of the metasurface unit structure, it exhibits the same polarization rotation characteristics for perpendicularly incident x-polarized and y-polarized waves. Taking the y-polarized wave as an example in this embodiment, the reflected electric field can be expressed as:
[0029] in, and φ represents the reflection coefficients of cross-polarization and co-polarization, respectively. xy and φ yy It is its corresponding phase, when r xy =r yy And Δφ=φ xy -φ yy When n = 2nπ ± π / 2, the reflected wave is a circularly polarized wave, where n is an integer.
[0030] As shown in Figure 3, there is an ultra-wide frequency range where r yy and r xy The phases are almost equal and the phase difference is approximately 90°. Within this range, the polarization converter transforms the incident linearly polarized wave into a circularly polarized wave.
[0031] As shown in Figure 4, when the incident angle is 0°, the linear-to-circular converter can maintain the axial ratio of the reflected wave below 3dB and achieve a bandwidth of 91.37% in the frequency range of 7.05GHz to 18.91GHz. When the incident angle is 20°, the linear-to-circular converter can maintain the axial ratio of the reflected wave below 3dB and achieve a bandwidth of 80.56% in the frequency range of 7.05GHz to 16.56GHz. When the incident angle is 40°, the converter's bandwidth can still be maintained within the range of 7.05 to 15.34GHz, with a relative bandwidth of 74.05%. This demonstrates that the polarization converter has an ultra-wide bandwidth and good angular stability.
[0032] To further explain the mechanism of polarization conversion, the xy coordinate system is rotated counterclockwise by 45° to obtain the uv coordinate system. In the uv coordinate system, the incident field can be expressed as: The reflected field can be represented as:
[0033] Where, r uu r vu r vv r uv These are the reflection coefficients for u-polarized and v-polarized incident waves, respectively. It is its corresponding phase. When r vu =r uv =0, r uu =r vv and When n is an integer, the reflected wave is a circularly polarized wave.
[0034] As shown in Figures 5 and 6, there is an ultra-wide frequency range where r vu and r uv Approximately equal to 0, r uu and r vv Approximately equal to 1 with a phase difference close to 90° or -270°. Within this range, the polarization converter transforms the incident linearly polarized wave into a circularly polarized wave.
[0035] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.
Claims
1. An ultrawideband linear circular polarization converter based on a wheel-shaped metasurface, characterized in that: The ultrawideband linear-circular polarization converter based on a wheel-shaped metasurface is composed of periodically arranged reflective polarization conversion units, and each reflective polarization conversion unit adopts a stacked structure. Each reflective polarization conversion unit includes an upper wheel-shaped metal pattern layer (1), an intermediate dielectric substrate (2), and a bottom metal layer (3). The upper surface of the intermediate dielectric substrate (2) is tightly connected to the upper wheel-shaped metal pattern layer (1), and the lower surface of the intermediate dielectric substrate (2) is tightly connected to the bottom metal layer (3). The upper wheel-shaped metal pattern layer (1), the intermediate dielectric substrate (2), and the bottom metal layer (3) work together to achieve polarization control function. Specifically, when a linearly polarized wave is incident on the ultrawideband linear-circular polarization converter, the upper wheel-shaped metal pattern layer (1) converts the incident linearly polarized wave into a circularly polarized wave, the intermediate dielectric substrate (2) extends the transmission path of the linearly polarized wave to generate resonance, and the bottom metal layer (3) is used to reflect the incident linearly polarized wave.
2. The ultrawideband linear circular polarization converter based on a wheel-shaped metasurface according to claim 1, characterized in that: The upper wheel-shaped metal pattern layer (1) is a wheel-shaped structure composed of cross-shaped metal sheets, circular metal sheets and rectangular metal strips. The cross-shaped metal sheets are symmetrically distributed along the diagonal direction with the center of the surface of the reflective polarization conversion unit as the symmetrical point. The cross-shaped metal sheets include orthogonal metal sheets in the long axis direction and metal sheets in the short axis direction. The metal sheets in the short axis direction are perpendicularly overlapped at the center point of the surface of the reflective polarization conversion unit. Two circular metal sheets are symmetrically arranged at the ends of the metal sheets in the long axis direction. The center of each circular metal sheet is located on the diagonal. Each circular metal sheet is provided with six rectangular metal strips of the same size. Each rectangular metal strip is rotate symmetrically distributed with the center of the circular metal sheet as the center at 30° equal angular intervals.
3. The ultrawideband linear circular polarization converter based on a wheel-shaped metasurface according to claim 2, characterized in that: The length L1 of the metal sheet along the major axis is 6.2 mm and the width W1 is 0.3 mm. The length L2 of the metal sheet along the minor axis is 0.8 mm and the width W2 is 0.4 mm. The distance between the center of the circular metal sheet and the center of the surface of the reflective polarization conversion unit is 3.1 mm. The diameter D of each circular metal sheet is 1.6 mm. The length L3 of each rectangular metal strip is 2 mm and the width W3 is 0.3 mm.
4. The ultrawideband linear circular polarization converter based on a wheel-shaped metasurface according to claim 1, characterized in that: The intermediate dielectric substrate (2) is selected with a relative permittivity ε r =4.3, FR4 dielectric material with loss tangent tanδ = 0.025, the dimensions of the intermediate dielectric substrate (2) are length × width × thickness = 8.2mm × 8.2mm × 2.4mm.
5. The ultrawideband linear circular polarization converter based on a wheel-shaped metasurface according to claim 1, characterized in that: The upper wheel-shaped metal pattern layer (1) and the bottom metal layer (3) are both made of copper material and have the same thickness, 0.035 mm.
6. The ultrawideband linear circular polarization converter based on a wheel-shaped metasurface according to claim 1, characterized in that: The side length p of the reflective polarization conversion unit is 8.2 mm.