A metasurface electromagnetic wave polarization controller based on a field-like shape

Abstract

The present invention relates to a metasurface electromagnetic wave polarization modulator based on a quasi - cross shape, which is composed of multiple polarization units arranged periodically in the same plane. It can achieve cross - polarization reflection of perpendicularly incident linearly polarized electromagnetic waves and belongs to the field of metasurface electromagnetic wave polarization state regulation. The feature of the present invention is that each polarization unit includes a metal layer at the bottom, a dielectric substrate in the middle, and a metal structure unit on the surface. The metal structure unit as a whole is in a quasi - "cross" shape, obtained by deforming the Chinese character "cross", and is an axially symmetric figure placed obliquely. The dielectric and metal materials used in the present invention are conventional materials, and within a certain frequency range, they can achieve polarization regulation of perpendicularly incident linearly polarized electromagnetic waves, with the advantages of being ultra - thin and easy to integrate, making up for the deficiencies of electromagnetic wave polarization modulators based on traditional materials.

Description

Technical Field

[0001] The present invention belongs to the field of supersurface electromagnetic wave polarization state regulation, and more specifically relates to a supersurface electromagnetic wave polarization regulator based on a T-shaped supersurface. Background Art

[0002] Polarization is one of the basic properties of electromagnetic waves and has a wide range of applications in many fields. With the increasing requirements for electromagnetic wave polarization controllers, electromagnetic wave polarization control devices based on traditional materials are large in size and difficult to integrate. The storage capacity of the materials used in nature is very limited, and the cost is also relatively high. People are in urgent need of new technical means to achieve the control of electromagnetic wave polarization.

[0003] Metamaterials are composed of subwavelength structural units. The subwavelength structural units in metamaterials are similar to atoms or molecules in conventional materials. Changing the structural units and their arrangement in metamaterials can change the properties of metamaterials. At present, people have used metamaterials to achieve novel phenomena such as negative refraction and anomalous Doppler effect. Metasurfaces are two-dimensional forms of three-dimensional structural metamaterials. They are also composed of subwavelength structural units, and the thickness of the metasurface is also subwavelength. Compared with three-dimensional structural metamaterials, metasurfaces have the advantages of light weight and easy processing.

[0004] At present, some common metasurfaces have only a single-layer structure, while others are multi-layered. Since the thickness of the metasurface is sub-wavelength, we can greatly reduce the loss of the metasurface by selecting its constituent materials and designing the structural form of its structural units. Therefore, metasurfaces have broad application prospects in many fields. At present, metasurfaces have important application value in the fields of electromagnetic wave polarization control, holography, focusing and antennas.

[0005] The reason why metasurfaces have important applications in the field of electromagnetic wave polarization control is that their materials have obvious differences in different directions, and they can accumulate phase differences at a shorter distance to achieve polarization control of electromagnetic waves. It can be seen that the research on metasurface electromagnetic wave polarization controllers is particularly important. Compared with traditional electromagnetic wave polarization control devices, metasurface electromagnetic wave polarization controllers are very small in size, but their efficiency is very high. Because of the above advantages, metasurface electromagnetic wave polarization controllers have attracted widespread research interest from researchers in recent years. Summary of the invention

[0006] The purpose of the present invention is to address the shortcomings of electromagnetic wave polarization control devices based on traditional materials, utilize the advantages of metasurfaces, and design a reflective metasurface electromagnetic wave polarization controller based on a T-shaped shape to achieve control of the polarization state of electromagnetic waves through reflection.

[0007] The present invention is implemented as follows. A metasurface electromagnetic wave polarization modulator based on a quasi - cross - shaped structure is composed of multiple polarization units arranged periodically in the same plane.

[0008] Each polarization unit of the metasurface electromagnetic wave polarization modulator includes a metal layer at the bottom, a dielectric substrate in the middle, and a metal structure unit on the surface layer. The dielectric substrate is located above the metal layer at the bottom, and the metal structure unit on the surface layer is located above the dielectric substrate. Moreover, the line connecting the centers of the bottom layer, the middle layer, and the surface layer is perpendicular to the bottom layer, the middle layer, and the surface layer simultaneously.

[0009] For the metal layer at the bottom and the metal structure unit on the surface layer, metal materials such as copper, gold, and aluminum can be selected. After optimization design, copper is preferably used as the metal material for the surface layer and the bottom layer.

[0010] The geometric parameters of the metal layer at the bottom are as follows:

[0011] 8mm ≤ a ≤ 13.6mm, 0.017mm ≤ b ≤ 0.036mm;

[0012] a represents the side length of the metal layer at the bottom, and b represents the thickness of the metal layer at the bottom.

[0013] The metal structure unit on the surface layer is an axially symmetric figure placed obliquely, and the overall shape is quasi - cross - shaped. It is obtained by etching the deformation of the Chinese character 'tian' on a square metal film. Each stroke of the 'tian' character should be appropriately extended, and a circle with a radius of r is etched at the center of the 'tian' character.

[0014] The geometric parameters of the metal structure unit on the surface layer are as follows:

[0015] 7mm ≤ c ≤ 13.4mm, 8mm ≤ L1 ≤ 19mm, 7.8mm ≤ T1 ≤ 12mm,

[0016] 5.6mm ≤ T2 ≤ 9mm, 2mm ≤ p ≤ 3mm, 0.4mm ≤ e ≤ 0.5mm, 0.017mm ≤ b ≤ 0.036mm; 0mm ≤ r ≤ 1.7mm;

[0017] Among them, c represents the side length of the square metal film on the surface layer, b represents the thickness of the metal structure unit, L 1、 T 1、 T2 represents the length of each stroke of the deformed 'tian' character, p represents the stroke spacing, and e represents the width of each stroke.

[0018] The dielectric substrate disposed between the metal structure unit on the surface layer and the metal layer at the bottom uses conventional dielectric materials, including Taconic series (TLT, TLX, TLY, TSM 30), Rogers series (RO, RT, TMM), Preterm series, etc.

[0019] Preferably, the Taconic TLY-5 (lossy) dielectric substrate has a relative dielectric constant ε r = 2.2 and a loss tangent of tanδ = 0.0009.

[0020] The geometric parameters of the dielectric substrate are as follows:

[0021] 8 mm ≤ a ≤ 13.6 mm, 1 mm ≤ h ≤ 2.5 mm;

[0022] where a represents the side length of the square dielectric substrate and h represents the thickness of the dielectric substrate.

[0023] The feature of the present invention is that by appropriately adjusting its geometric parameters, the frequency range for realizing the polarization rotation of electromagnetic waves can be changed to a certain extent.

[0024] In view of the deficiencies of the electromagnetic wave polarization control devices based on traditional materials, the present invention designs a super-surface polarization controller based on a quasi-square-grid, which can accumulate the phase difference over a short distance and realize the control of the polarization state of electromagnetic waves.

[0025] The present invention has the following advantages:

[0026] 1. The present invention is designed with conventional dielectric materials and metal materials, which are widely available and inexpensive.

[0027] 2. The present invention can accumulate the phase difference over a short distance, and the polarization unit has a small size and is easy to integrate.

[0028] 3. Within a certain frequency range, the present invention can realize the polarization control of linearly polarized electromagnetic waves incident vertically through reflection, and the cross-polarization reflectivity of the present invention can reach up to about 99%.

[0029] 4. By appropriately adjusting its geometric parameters, the present invention can change the frequency range for realizing the polarization control of electromagnetic waves within a certain range, and the present invention has the characteristics of flexibility and wide application.

[0030] 5. The present invention has the characteristic of broadband, and the bandwidth with a cross-polarization reflectivity greater than 90% can reach about 13 GHz. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 FIG. is a three-dimensional structural schematic diagram of nine polarization units of a super-surface electromagnetic wave polarization controller based on a quasi-square-grid according to the present invention;

[0032] Figure 2 FIG. is a front structural schematic diagram of a polarization unit of a super-surface electromagnetic wave polarization controller based on a quasi-square-grid according to the present invention;

[0033] Figure 3It is a schematic diagram of the side structure of a polarization unit of a metasurface electromagnetic wave polarization regulator based on a zigzag shape according to the present invention;

[0034] Figure 4 A schematic diagram of the principle of realizing cross-polarization reflection in the present invention;

[0035] Figure 5 is a phase difference curve diagram of the present invention;

[0036] Figure 6 is the cross-polarization reflectivity of Example 1 of the present invention;

[0037] Figure 7 is the cross-polarization reflectivity of embodiment 2 of the present invention;

[0038] Figure 8 It is the cross-polarization reflectivity of Example 3 of the present invention.

[0039] Explanation of the reference numerals: 1-1 - metal structural unit of the surface layer, 1-2 - dielectric substrate in the middle, 1-3 - metal layer of the bottom layer. DETAILED DESCRIPTION

[0040] The technical route of the present invention is further described below in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the several groups of specific geometric structure parameters listed are only a part of the geometric parameter group of the present invention, rather than the entire parameter range. Based on the embodiments of the present invention, the embodiments that have not been innovatively improved by those skilled in the art are still the scope to be protected by the present invention.

[0041] like Figure 1 As shown, the present invention designs a metasurface electromagnetic wave polarization regulator based on a T-shaped metasurface, which is composed of multiple polarization units periodically arranged in the same plane.

[0042] like Figure 3 As shown, each polarization unit includes a bottom metal layer (1-3), a middle dielectric substrate (1-2) and a surface metal structure unit (1-1).

[0043] The dielectric substrate is pasted on the bottom metal layer, the surface metal structure unit is pasted on the dielectric substrate, and the connecting line of the centers of the bottom layer, the middle layer and the surface layer is perpendicular to the bottom layer, the middle layer and the surface layer.

[0044] The bottom metal layer (1-3) and the surface metal structural unit (1-1) can be made of metal materials such as copper, gold and aluminum.

[0045] The bottom metal layer geometry parameters are as follows:

[0046] 8 mm ≤ a ≤ 13.6 mm, 0.017 mm ≤ b ≤ 0.036 mm.

[0047] Such as Figure 2 , the metal structure units (1-1) on the surface layer are axially symmetric figures placed obliquely, and the overall shape is similar to the Chinese character "field". It is obtained by etching the deformation of the Chinese character "field" on a square metal film. Each stroke of the "field" character should be appropriately extended, and a circle with a radius of r is etched at the center of the "field" character.

[0048] The geometric parameters of the metal structure units on the surface layer are as follows:

[0049] 7 mm ≤ c ≤ 13.4 mm, 8 mm ≤ L1 ≤ 19 mm, 7.8 mm ≤ T1 ≤ 12 mm,

[0050] 5.6 mm ≤ T2 ≤ 9 mm, 2 mm ≤ p ≤ 3 mm, 0.4 mm ≤ e ≤ 0.5 mm, 0.017 mm ≤ b ≤ 0.036 mm; 0 mm ≤ r ≤ 1.7 mm;

[0051] Among them, c represents the side length of the square metal film on the surface layer, b represents the thickness of the metal structure unit, L 1、 T 1、 T2 represents the length of each stroke of the deformed "field" character, p represents the stroke spacing, and e represents the width of each stroke.

[0052] The dielectric substrate disposed between the top metal structure unit and the bottom metal layer uses conventional dielectric materials, including Taconic series (TLT, TLX, TLY, TSM 30), Rogers series (RO, RT, TMM), Preterm series, etc. Preferably, Taconic TLY-5 (lossy) dielectric substrate is used, and its relative dielectric constant Ɛ r = 2.2, and the tangent value of the loss angle is tanδ = 0.0009.

[0053] The geometric parameters of the dielectric substrate are as follows:

[0054] 8 mm ≤ a ≤ 13.6 mm, 1 mm ≤ h ≤ 2.5 mm;

[0055] Among them, a represents the side length of the dielectric substrate, and h represents the thickness of the dielectric substrate.

[0056] The three groups of embodiments of the present invention provide three groups of different geometric parameters, which to a certain extent reflect the feature that by appropriately adjusting the geometric parameters of the present invention, the frequency range for realizing electromagnetic wave polarization control can be changed to a certain extent.

[0057] The schematic diagram of the principle for the present invention to achieve polarization control of electromagnetic waves is as Figure 4As shown, it is assumed that the incident wave is a linearly polarized wave propagating along the z-axis direction. In order to better explain the working principle of the present invention, the xoy coordinate system is rotated 45 degrees counterclockwise to obtain the uov coordinate system, and the incident wave polarized in the y direction is E i Decompose in the u and v directions, and we get E iu , E iv The two parts of the electromagnetic wave polarized perpendicular to the incident line can be expressed as: E i e y = E iu e u +E iv e v , the reflected wave formed by the incident wave after the metasurface can be expressed as: E r e x = E ru e u +E rv e v =r u E iu e u +r v E iv e v ,in r u , r v Respectively expressed in u Polarization and v Polarization reflection coefficient. When | r u |≈| r v | , r u and r v The phase difference Δφ=φ u -φ v =180°, the polarization direction of the reflected wave is along the x direction, that is, the vertical incident line polarized wave produces a cross-polarized reflection. Figure 5We found that in the ranges of 11.46 GHz - 16.56 GHz and 16.59 GHz - 23.13 GHz, the difference between the phase difference Δφ and the 180-degree reference line (dashed line) is within ±40°, and the phase differences at the two frequency points of 12 GHz and 16.77 GHz are almost ±180°, indicating that the incident linearly polarized electromagnetic waves at these two frequency points can be almost completely polarized.

[0058] The following further elaborates in detail on the function of the present invention to a certain extent for changing the electromagnetic wave polarization control range in combination with the specific geometric parameters in the embodiments.

[0059] Embodiment 1

[0060] In this embodiment, the bottom metal layer is a copper film with a width a = 9.2 mm and a thickness b = 0.035 mm; the middle dielectric substrate is a Taconic TLY-5 (lossy) dielectric substrate with a relative dielectric constant Ɛ r = 2.2, a loss tangent of tanδ = 0.0009, a width a = 9.2 mm, and a thickness h = 1.6 mm; the surface metal structure unit selects a copper film as its material, the width c of the square copper film is 8.4 mm, and the lengths of the strokes of the cross are L1 = mm, T1 = 8 mm, T2 = 5.8 mm, the stroke spacing p = 1.8 mm, the stroke width e = 0.4 mm, and the thickness b of the metal structure unit is 0.035 mm. We used software for simulation and calculated the phase difference of Embodiment 1 as Figure 5 shown, and its cross-polarization reflectivity is as Figure 6 shown. It can be seen that the frequency range with a cross-polarization reflectivity greater than 90% is 11.65 - 24.08 GHz, and the cross-polarization reflectivity is the largest at 17.075 GHz, with a maximum value of 99.2%.

[0061] Embodiment 2

[0062] In this embodiment, the bottom metal layer and the surface metal structure unit are copper films, and the middle dielectric substrate is still a Taconic TLY-5 (lossy) dielectric substrate. The geometric parameters of the polarization unit are changed to: a = 8 mm, b = 0.035 mm, c = 7.2 mm, L1 = mm, T1 = 7.8 mm, T2 = 5.6 mm, e = 0.4 mm. Continuing to use software for simulation, the cross-polarization reflectivity of Embodiment 2 is as Figure 7 shown. It can be seen that the frequency ranges with a cross-polarization reflectivity greater than 90% are 11.33 - 24.32 GHz and 25.48 - 26.07 GHz, and the cross-polarization rate is the largest at 17.05 GHz, with a maximum value of 99.2%.

[0063] Example 3

[0064] In this embodiment, the bottom metal layer and the surface metal structure unit still use copper film, and their geometric parameters are changed to: a=9.2mm, h=1.6mm; the middle dielectric substrate uses Rogers RT5880 (lossy) dielectric substrate, and its relative dielectric constant Ɛ r =2.2, the loss tangent is tanδ=0.0009, and its geometric parameters are changed to a=13.6mm, b=0.035mm, c=12.2mm, L1= mm, T1=12mm, T2=9mm, p=3mm, e=0.5mm. Continue to use software simulation to simulate and obtain the cross-polarization reflectivity of Example 3 as follows Figure 8 As shown, it can be seen that the cross-polarization reflectivity is greater than 90% in the frequency range of 8.12-16.48 GHz, and the cross-polarization rate is the largest at 12.072 GHz, with a maximum value of 99.1%.

[0065] The present invention is not limited to the above-mentioned embodiments. Ordinary technicians in this field can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. If these modifications and modifications based on the present invention still fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A metasurface electromagnetic wave polarization controller based on a zigzag shape, which is composed of multiple polarization units periodically arranged in the same plane, characterized in that: Each polarization unit includes a metal layer (1-3) at the bottom, a dielectric substrate (1-2) in the middle, and a metal structure unit (1-1) on the surface layer. The connecting lines of the centers of the bottom layer, the middle layer, and the surface layer are perpendicular to the bottom layer, the middle layer, and the surface layer at the same time. The metal structure unit on the surface layer is an axially symmetric figure placed obliquely, and the overall shape is similar to the Chinese character "field". It is obtained by etching the deformation of the Chinese character "field" on a square metal film. The two ends of the three horizontal and three vertical lines of the character "field" are appropriately extended, that is, two groups of mutually perpendicular rectangular slits are etched. Each group has three parallel rectangular slits, and a circle with a radius of r is etched at the center of the character "field". The metal layer (1-3) at the bottom and the dielectric substrate (1-2) in the middle are both square. The geometric parameters of the metal structure unit on the surface layer are as follows: 7mm ≤ c ≤ 13.4mm, 8mm ≤ L1 ≤ 19mm, 7.8mm ≤ T1 ≤ 12mm, 5.6mm ≤ T2 ≤ 9mm, 2mm ≤ p ≤ 3mm, 0.4mm≤e≤0.5mm, 0.017mm≤b≤0.036mm; 0mm≤r≤1.7mm; where c represents the side length of the surface square metal film, b represents the thickness of the metal structure unit, L 1、 T 1、 T2 represents the length of the middle vertical, middle horizontal, and upper and lower horizontal lines of the deformed field character, p represents the stroke spacing, and e represents the width of each stroke.

2. The metasurface electromagnetic wave polarization regulator based on a quasi-cross shape according to claim 1, wherein The metal layer at the bottom and the metal structure unit on the surface layer are made of copper, gold or aluminum metal.

3. The metasurface electromagnetic wave polarization modulator based on a quasi-cross shape as claimed in claim 1, wherein The geometric parameters of the metal layer at the bottom are as follows: 8mm ≤ a ≤ 13.6mm, 0.017mm ≤ b ≤ 0.036mm; a represents the side length of the metal layer at the bottom, and b represents the thickness of the metal layer at the bottom.

4. A metasurface electromagnetic wave polarization modulator based on a quasi-cross shape as claimed in claim 1, wherein The dielectric substrate disposed between the metal structure unit on the surface layer and the metal layer at the bottom is made of a conventional dielectric material, including TLT, TLX, TLY, TSM 30 of the Taconic series, RO, RT, TMM of the Rogers series, the Preterm series, etc.

5. The metasurface electromagnetic wave polarization modulator based on a quasi-checkerboard as claimed in claim 4, wherein, The geometric parameters of the dielectric substrate are as follows: 8mm ≤ a ≤ 13.6mm, 1mm ≤ h ≤ 2.5mm; Where a represents the side length of the dielectric substrate, and h represents the thickness of the dielectric substrate.

6. A metasurface electromagnetic wave polarization controller based on a zigzag shape as claimed in claim 1, characterized in that By appropriately adjusting its geometric parameters, the frequency range for realizing electromagnetic wave polarization regulation can be changed.

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