Double-frequency-point polarization conversion electromagnetic induction unit, design method and transparent structure

Abstract

The invention discloses a double-frequency-point polarization conversion electromagnetic induction unit, a design method and a transparent structure, and the double-frequency-point polarization conversion electromagnetic induction unit structurally comprises a dielectric substrate, a first metal patch combination structure and a second metal patch combination structure. The first metal patch combination structure is composed of a metal sheet shaped like a Chinese character'tu 'and an I-shaped metal sheet; the second metal patch combination structure is composed of an I-shaped metal sheet and a metal sheet shaped like a Chinese character'shi '; the first metal patch combination structure and the second metal patch combination structure are distributed at the left end and the right end or the upper end and the lower end of the dielectric substrate in an asymmetrical mode. The polarization converter solves the problems that an existing polarization converter based on the electromagnetism-like induced transparency effect can only achieve single-frequency-point polarization conversion, and the polarization conversion position has large transmission loss.

Description

Technical Field

[0001] The present invention belongs to the field of communication technologies, and particularly relates to a dual-frequency polarization conversion electromagnetic induction unit, a design method, and a transparent structure. Background Art

[0002] EIT (Electromagnetically-induced Transparency) is a very important phenomenon in atomic physics. Its essence is that under resonance conditions, that is, when the frequency of light matches the corresponding atomic transition frequency, the quantum destructive interference between the light-atom excitation channels causes a very narrow transmission peak to appear in a wide absorption band of the medium. Later, EIT was also applied to the microwave and terahertz bands, manifested as a relatively narrow transmission peak formed within a wide non-transmission frequency band. The EIT structure can change the dispersion properties and slow down the speed of light, and has important applications in nonlinear devices, slow light devices, filters, sensors, and optical storage, etc. Traditional polarization converters will cause high losses during the conversion process, and their phase adjustment ability is limited, which restricts their application potential in phase mutation-triggered delay devices.

[0003] Therefore, a polarization converter based on the electromagnetic-induced transparency-like effect is proposed. It has an ultra-thin thickness and excellent transmission performance, and has potential application value in the fields of compact antennas, derivative radar phased arrays, and military industrial detectors. However, the polarization converter based on the electromagnetic-induced transparency-like effect can only achieve single-frequency polarization conversion, which restricts its application potential and the scope of application scenarios in working scenarios.

[0004] In order to solve the problem that the polarization converter based on the electromagnetic-induced transparency-like effect can only achieve single-frequency polarization conversion and has a large transmission loss at the polarization conversion, a dual-frequency polarization conversion electromagnetic induction unit, a design method, and a transparent structure are proposed. Summary of the Invention

[0005] An embodiment of the present invention proposes a dual-frequency polarization conversion electromagnetic induction unit, a design method, and a transparent structure to at least solve the problem that the existing polarization converter based on the electromagnetic-induced transparency-like effect can only achieve single-frequency polarization conversion and has a large transmission loss at the polarization conversion.

[0006] According to an embodiment of the present invention, a dual-frequency polarization conversion electromagnetic induction unit is provided, and its structure includes: a dielectric substrate, a first metal patch combination structure, and a second metal patch combination structure; the dielectric substrate is a square dielectric plate;

[0007] The first metal patch combination structure is jointly composed of a "tu"-shaped metal sheet and a "gong"-shaped metal sheet; the horizontal sides of the "tu"-shaped metal sheet and the "gong"-shaped metal sheet are parallel to each other, and the vertical sides are parallel to each other;

[0008] The second metal patch combination structure is jointly composed of an "I"-shaped metal sheet and a "士"-shaped metal sheet; the horizontal sides of the "I"-shaped metal sheet and the "士"-shaped metal sheet are parallel to each other, and the vertical sides are parallel to each other;

[0009] The first metal patch combination structure and the second metal patch combination structure are distributed at the left and right ends or the upper and lower ends of the dielectric substrate, presenting an asymmetric distribution;

[0010] The deployment positions of the first metal patch combination structure and the second metal patch combination structure are obtained according to the influence degree of the asymmetry between the first metal patch combination structure and the second metal patch combination structure on the transmission wave phase difference and the functional relationship between the transmission wave phase difference and the axial ratio, so as to achieve dual-frequency polarization conversion.

[0011] In an exemplary embodiment, the dielectric substrate is composed of a layer of Rogers RO5880 dielectric layer with a relative dielectric constant of 2.2; the material of the metal sheets in the first metal patch combination structure and the second metal patch combination structure is copper.

[0012] In an exemplary embodiment, the length of the long horizontal side of the "土"-shaped metal sheet is the same as that of the long horizontal side of the "士"-shaped metal sheet; the length of the short horizontal side of the "土"-shaped metal sheet is the same as that of the short horizontal side of the "士"-shaped metal sheet; the length of the vertical side of the "土"-shaped metal sheet is the same as that of the vertical side of the "士"-shaped metal sheet.

[0013] In an exemplary embodiment, the "I"-shaped metal sheet of the first metal patch combination structure has the same shape and size as the "I"-shaped metal sheet of the second metal patch combination structure; the lengths of the sides of the "I"-shaped metal sheet are not the same as the lengths of the sides of the "土"-shaped metal sheet and the "士"-shaped metal sheet.

[0014] In an exemplary embodiment, the asymmetry between the first metal patch combination structure and the second metal patch combination structure is calculated according to the positive correlation between the length difference between the long horizontal side and the short horizontal side of the "土"-shaped metal sheet and the "士"-shaped metal sheet and / or the length difference of the horizontal sides of the "I"-shaped metal sheet and / or the length difference between the vertical sides of the "土"-shaped metal sheet and the "士"-shaped metal sheet and the vertical sides of the "I"-shaped metal sheet and / or the angle between the straight lines where the vertical sides of the two "I"-shaped metal sheets are located and the degree of asymmetry.

[0015] In an exemplary embodiment, the deployment positions of the first metal patch combination structure and the second metal patch combination structure are obtained based on the influence degree of the asymmetry between the first metal patch combination structure and the second metal patch combination structure on the transmission wave phase difference and the functional relationship between the transmission wave phase difference and the axial ratio, including the steps:

[0016] Calculate the transmission wave phase difference function according to the influence degree of the asymmetry between the first metal patch combination structure and the second metal patch combination structure on the transmission wave phase difference;

[0017] Calculate the axial ratio function according to the functional relationship between the transmission wave phase difference and the axial ratio;

[0018] Substitute the transmission wave phase difference function into the axial ratio function to obtain the axial ratio - asymmetry degree correlation function;

[0019] Calculate the minimum value of the axial ratio - asymmetry degree correlation function to obtain the target asymmetry degree between the first metal patch combination structure and the second metal patch combination structure;

[0020] Obtain the deployment positions of the first metal patch combination structure and the second metal patch combination structure according to the target asymmetry degree between the first metal patch combination structure and the second metal patch combination structure.

[0021] In an exemplary embodiment, the "I"-shaped metal sheets of the first metal patch combination structure and the "I"-shaped metal sheets of the second metal patch combination structure are symmetrically distributed along the diagonal of the dielectric substrate. <​​​​​​​​​​​​​​​Calculating the minimum value of the function related to the axial ratio and the asymmetry to obtain the target asymmetry of the first metal patch combination structure and the second metal patch combination structure;

[0028] The first metal patch combination structure and the second metal patch combination structure are adjusted according to the target asymmetry between the first metal patch combination structure and the second metal patch combination structure and the relationship between the asymmetry and structure of the first metal patch combination structure and the second metal patch combination structure, so as to obtain a dual-frequency polarization conversion electromagnetic induction unit structure.

[0029] According to another embodiment of the present invention, a dual-frequency polarization conversion electromagnetic induction transparent structure is provided, which is constructed by arranging the above-mentioned dual-frequency polarization conversion electromagnetic induction units according to a preset period, and the arrangement period of the dual-frequency polarization conversion electromagnetic induction units is greater than or equal to the side length of the dielectric substrate.

[0030] The dual-frequency polarization conversion electromagnetic induction unit, design method, and transparent structure of the present invention have the following advantages:

[0031] (1) A first metal patch combination structure and a second metal patch combination structure are used in a single-layer frequency selective surface to simultaneously realize filtering and polarization rotation functions based on a similar electromagnetically induced transparency effect. Compared with traditional polarization conversion devices, lower device loss and higher phase adjustment capability can be achieved.

[0032] (2) The first metal patch combination structure and the second metal patch combination structure adopt an asymmetric distribution structure, which stimulates a multi-level clear mode path. Compared with the traditional EIT-based polarization conversion device, it can effectively realize dual-frequency polarization conversion.

[0033] (3) The first metal patch combination structure and the second metal patch combination structure are adjusted by the degree of influence of asymmetry on the phase difference of the transmitted wave and the functional relationship between the phase difference of the transmitted wave and the axial ratio. That is, by adjusting the asymmetry of the presented structure in each direction, the desired phase difference is obtained, thereby realizing LTC polarization conversion through EIT excitation. Compared with the traditional EIT-based polarization conversion device, a better circular polarization conversion window can be obtained, which greatly reduces the transmission loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a structural diagram of a dual-frequency polarization conversion electromagnetic induction unit according to an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure and dimensions of a dual-frequency polarization conversion electromagnetic induction unit according to an embodiment of the present invention;

[0036] Figure 3 This is a flow chart of a design method for a dual-frequency polarization conversion electromagnetic induction unit according to an embodiment of the present invention;

[0037] Figure 4 It is the simulation performance diagram of the dual - frequency polarization conversion electromagnetic induction unit of the embodiment of the present invention. Detailed implementation manners

[0038] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the invention, but do not limit the invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made. These all belong to the protection scope of the present invention.

[0039] According to an embodiment of the present invention, a dual - frequency polarization conversion electromagnetic induction unit is provided. The schematic diagram is as Figure 1 shown, and its structure includes: a dielectric substrate (1), a first metal patch combination structure (2), and a second metal patch combination structure (3); the dielectric substrate (1) is a square dielectric plate;

[0040] The first metal patch combination structure (2) is jointly composed of a "tu" - shaped metal sheet (21) and a "gong" - shaped metal sheet (22); the horizontal sides of the "tu" - shaped metal sheet and the "gong" - shaped metal sheet are parallel to each other, and the vertical sides are parallel to each other;

[0041] The second metal patch combination structure (3) is jointly composed of a "gong" - shaped metal sheet (31) and a "shi" - shaped metal sheet (32); the horizontal sides of the "gong" - shaped metal sheet and the "shi" - shaped metal sheet are parallel to each other, and the vertical sides are parallel to each other;

[0042] The first metal patch combination structure (2) and the second metal patch combination structure (3) are distributed at the left and right ends or the upper and lower ends of the dielectric substrate, showing an asymmetric distribution; Figure 1 In the shown structure, the first metal patch combination structure (2) and the second metal patch combination structure (3) are distributed at the left and right ends of the dielectric substrate.

[0043] The deployment positions of the first metal patch combination structure and the second metal patch combination structure are obtained according to the influence degree of the asymmetry degree of the first metal patch combination structure and the second metal patch combination structure on the transmission wave phase difference and the functional relationship between the transmission wave phase difference and the axial ratio, so as to achieve dual - frequency polarization conversion.

[0044] In an exemplary embodiment, the dielectric substrate is composed of a layer of Rogers RO5880 dielectric layer with a relative dielectric constant of 2.2; the material of the metal sheets in the first metal patch combination structure and the second metal patch combination structure is copper.

[0045] In an exemplary embodiment, the length of the long horizontal side of the "tu" - shaped metal sheet is the same as that of the long horizontal side of the "shi" - shaped metal sheet; the length of the short horizontal side of the "tu" - shaped metal sheet is the same as that of the short horizontal side of the "shi" - shaped metal sheet; the length of the vertical side of the "tu" - shaped metal sheet is the same as that of the vertical side of the "shi" - shaped metal sheet. In this embodiment, the schematic diagram of the unit structure size is as shown in Figure 2 shown. The length of the long horizontal side of the "tu" - shaped metal sheet and that of the long horizontal side of the "shi" - shaped metal sheet are represented by L1, the length of the short horizontal side of the "tu" - shaped metal sheet and that of the short horizontal side of the "shi" - shaped metal sheet are represented by L2, and the length of the vertical side of the "tu" - shaped metal sheet and that of the vertical side of the "shi" - shaped metal sheet are represented by L3.

[0046] In an exemplary embodiment, the "gong" - shaped metal sheet of the first metal patch combination structure has the same shape and size as the "gong" - shaped metal sheet of the second metal patch combination structure; the lengths of each side of the "gong" - shaped metal sheet are not the same as those of the "tu" - shaped metal sheet and the "shi" - shaped metal sheet. In this embodiment, the "gong" - shaped metal sheet of the first metal patch combination structure and the "gong" - shaped metal sheet of the second metal patch combination structure are completely identical in shape and size, as shown in Figure 2 shown, and the lengths of each side of the "gong" - shaped metal sheet are represented by L4, L5, and L6 respectively.

[0047] Preferably, the "gong" - shaped metal sheet of the first metal patch combination structure and the "gong" - shaped metal sheet of the second metal patch combination structure are symmetrically distributed along the diagonal of the dielectric substrate.

[0048] Preferably, the length L1 of the long horizontal side of the "tu" - shaped metal sheet and that of the long horizontal side of the "shi" - shaped metal sheet is 16 mm, the length L2 of the short horizontal side is 5.3 mm, and the length L3 of the vertical side is 5.8 mm; the length L5 of the long horizontal side of the "gong" - shaped metal sheet is 9 mm, the length L4 of the short horizontal side is 3.1 mm, and the length L6 of the vertical side is 8.5 mm; the side length P of the dielectric substrate is 35 mm, the thickness h1 of the dielectric substrate is 1 mm, and the thickness h2 of the metal sheet is greater than 10 μm. <o

[0049] In an exemplary embodiment, the asymmetry between the first metal patch combination structure and the second metal patch combination structure is calculated based on the positive correlation between the length difference between the long and short horizontal sides of the "tu" - shaped metal sheet and the "shi" - shaped metal sheet and / or the length difference between the horizontal sides of the "gong" - shaped metal sheet and / or the length difference between the vertical sides of the "tu" - shaped metal sheet and the "shi" - shaped metal sheet and the vertical sides of the "gong" - shaped metal sheet and / or the angle between the straight lines where the vertical sides of the two "gong" - shaped metal sheets are located and the degree of asymmetry. That is, the asymmetry between the first metal patch combination structure and the second metal patch combination structure is calculated based on the positive correlation between the difference between L1 and L2 and the degree of asymmetry, or based on the positive correlation between the difference between L3 and L6 and the degree of asymmetry, or based on the positive correlation between the angle between the straight lines where the vertical sides of the two "gong" - shaped metal sheets are located and the degree of asymmetry, or based on the positive correlation between the difference between L1 and L2 and the difference between L3 and L6 and the degree of asymmetry, or based on the positive correlation between the difference between L1 and L2 and the angle between the straight lines where the vertical sides of the two "gong" - shaped metal sheets are located and the degree of asymmetry, or based on the positive correlation between the difference between L3 and L6 and the angle between the straight lines where the vertical sides of the two "gong" - shaped metal sheets are located and the degree of asymmetry, or based on the positive correlation between the difference between L1 and L2, the difference between L3 and L6, and the angle between the straight lines where the vertical sides of the two "gong" - shaped metal sheets are located and the degree of asymmetry. The difference between L1 and L2 is denoted as the first dimension difference, represented by the variable l, where l = L1 - L2; the difference between L3 and L6 is denoted as the second dimension difference, represented by the variable w, where w = L6 - L3; the angle between the straight lines where the vertical sides of the two "gong" - shaped metal sheets are located is denoted as the structural deviation value, represented by the variable r; the asymmetry between the first metal patch combination structure and the second metal patch combination structure is represented by the variable s.

[0050] Examples A1 - A7 are used to represent different embodiments for calculating the asymmetry between the first metal patch combination structure and the second metal patch combination structure.

[0051] Example A1: Calculate the asymmetry between the first metal patch combination structure and the second metal patch combination structure based on the first dimension difference.

[0052] Specifically, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated based on the positive correlation between the first size difference l and the asymmetry of the first metal patch combination structure and the second metal patch combination structure. In a preferred embodiment, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated as follows: o2 +o3, where o1, o2 (o2>0), and o3 are calculation coefficients obtained by prior training. In this embodiment, the first size difference l = L1-L2 = 10.7 mm, the preset first size difference threshold (18 mm) is calculated and normalized, and the first size difference (normalized) is 10.7 / 18≈0.6; the calculation coefficients o1 = 1, o2 = 1, and o3 = 0 obtained by prior training are calculated, and the asymmetry s = o1·l between the first metal patch combination structure and the second metal patch combination structure is calculated. o2 +o3=1×0.6+0=0.6.

[0053] Embodiment A2: Calculating the asymmetry between the first metal patch combination structure and the second metal patch combination structure based on the second size difference.

[0054] Specifically, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated based on the positive correlation between the second size difference w and the asymmetry of the first metal patch combination structure and the second metal patch combination structure. In a preferred embodiment, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated as follows: o5 +o6, where o4, o5 (o5>0), and o6 are pre-trained calculation coefficients. In this embodiment, the second size difference w = L6-L3 = 2.7mm, the preset second size difference threshold (3.86mm) is calculated and normalized, and the second size difference (normalized) is 2.7 / 3.86≈0.7; the pre-trained calculation coefficients o4 = 1, o5 = 1, and o6 = 0 are calculated, and the asymmetry s = o4·w between the first metal patch combination structure and the second metal patch combination structure is calculated. o5 +o6=1×0.7+0=0.7.

[0055] Example A3: Calculating the asymmetry between the first metal patch combination structure and the second metal patch combination structure based on the structural deviation value.

[0056] Specifically, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated based on the positive correlation between the structural deviation value r and the asymmetry of the first metal patch combination structure and the second metal patch combination structure. In a preferred embodiment, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated as follows: o8+o9, where o7, o8 (o8>0), and o9 are calculation coefficients obtained through pre-training. In this embodiment, assuming that the absolute value of the angle between the vertical sides of the two "I"-shaped metal sheets is 10°, that is, the structural deviation value r=10, the preset structural deviation threshold (12.5°) is calculated and normalized to obtain a structural deviation value (normalized) of 10 / 12.5=0.8; the calculation coefficients o7=1, o8=1, and o9=0 obtained through pre-training are used to calculate the asymmetry s=o7·r between the first metal patch combination structure and the second metal patch combination structure. o8 +o9=1×0.8+0=0.8.

[0057] Example A4: Calculating the asymmetry between the first metal patch combination structure and the second metal patch combination structure based on the first size difference and the second size difference.

[0058] Specifically, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated based on the positive correlation between the first size difference l and the second size difference w and the asymmetry of the first metal patch combination structure and the second metal patch combination structure. In a preferred embodiment, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated as 010·l o11 +o12·w o13 , where o10, o11 (o11>0), o12, and o13 (o13>0) are calculation coefficients obtained through pre-training. In this embodiment, the first size difference l=L1-L2=10.7mm, the preset first size difference threshold (18mm) is calculated for normalization, and the first size difference (normalized) is 10.7 / 18≈0.6; the second size difference w=L6-L3=2.7mm, the preset second size difference threshold (3.86mm) is calculated for normalization, and the second size difference (normalized) is 2.7 / 3.86≈0.7; the calculation coefficients o10=0.7, o11=1, o12=0.3, and o13=1 obtained through pre-training are used to calculate the asymmetry s=o10·l between the first metal patch combination structure and the second metal patch combination structure. o11 +o12·w o13 =0.7×0.6+0.3×0.7=0.63. In another preferred embodiment, the asymmetry between the first metal patch combination structure and the second metal patch combination structure is calculated as s=o14·l o15 w o16+o17, where o14, o15 (o15>0), o16 (o16>0), and o17 are calculation coefficients obtained through pre-training. In this embodiment, the first size difference l=L1-L2=10.7mm, the preset first size difference threshold (18mm) is calculated for normalization, and the first size difference (normalized) is 10.7 / 18≈0.6; the second size difference w=L6-L3=2.7mm, the preset second size difference threshold (3.86mm) is calculated for normalization, and the second size difference (normalized) is 2.7 / 3.86≈0.7; the calculation coefficients o14=1.5, o15=1, o16=1, and o17=0 obtained through pre-training are used to calculate the asymmetry s=o14·l of the first metal patch combination structure and the second metal patch combination structure. o15 w o16 +o17=1.5×0.6×0.7+0=0.63.

[0059] Embodiment A5: Calculating the asymmetry between the first metal patch combination structure and the second metal patch combination structure based on the first size difference and the structure deviation value.

[0060] Specifically, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated based on the positive correlation between the first size difference l and the structure deviation value r and the asymmetry of the first metal patch combination structure and the second metal patch combination structure. In a preferred embodiment, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated as follows: o19 +o20·r o21 , where o18, o19 (o19>0), o20, and o21 (o21>0) are calculation coefficients obtained through prior training. In this embodiment, the first size difference l=L1-L2=10.7mm, the preset first size difference threshold (18mm) is calculated for normalization, and the first size difference (normalized) is 10.7 / 18≈0.6; assuming that the absolute value of the angle between the vertical sides of the two "I"-shaped metal sheets is 10°, that is, the structural deviation value r=10, the preset structural deviation threshold (12.5°) is calculated for normalization, and the structural deviation value (normalized) is 10 / 12.5=0.8; the calculation coefficients o18=0.8, o19=1, o20=0.2, and o21=1 obtained through prior training are calculated, and the asymmetry s=o18·l between the first metal patch combination structure and the second metal patch combination structure is calculated. o19 +o20·r o21 =0.8×0.6+0.2×0.8=0.64. In another preferred embodiment, the asymmetry between the first metal patch combination structure and the second metal patch combination structure is calculated as s=o22·l o23 ·r o23+o25, where o22, o23 (o23>0), o24 (o24>0), and o25 are calculation coefficients obtained through prior training. In this embodiment, the first size difference l=L1-L2=10.7mm, the preset first size difference threshold (18mm) is calculated for normalization, and the first size difference (normalized) is 10.7 / 18≈0.6; assuming that the absolute value of the angle between the vertical sides of the two "I"-shaped metal sheets is 10°, that is, the structural deviation value r=10, the preset structural deviation threshold (12.5°) is calculated for normalization, and the structural deviation value (normalized) is 10 / 12.5=0.8; the calculation coefficients o22=1.35, o23=1, o24=1, and o25=0 obtained through prior training are calculated, and the asymmetry s=o22·l between the first metal patch combination structure and the second metal patch combination structure is calculated. o23 ·r o23 +o25=1.35×0.6×0.8+0=0.648.

[0061] Example A6: Calculating the asymmetry between the first metal patch combination structure and the second metal patch combination structure based on the second size difference and the structure deviation value.

[0062] Specifically, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated based on the positive correlation between the second size difference w and the structure deviation r and the asymmetry of the first metal patch combination structure and the second metal patch combination structure. In a preferred embodiment, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated as follows: o27 +o28·r o29 , where o26, o27 (o27>0), o28, and o29 (o29>0) are calculation coefficients obtained through pre-training. In this embodiment, the second size difference w=L6-L3=2.7mm, the preset second size difference threshold (3.86mm) is calculated for normalization, and the second size difference (normalized) is 2.7 / 3.86≈0.7; assuming that the absolute value of the angle between the vertical sides of the two "I"-shaped metal sheets is 10°, that is, the structural deviation r=10, the preset structural deviation threshold (12.5°) is calculated for normalization, and the structural deviation (normalized) is 10 / 12.5=0.8; the calculation coefficients o26=0.7, o27=1, o28=0.3, and o29=1 obtained through pre-training are used to calculate the asymmetry s=o26·w between the first metal patch combination structure and the second metal patch combination structure. o27 +o28·r o29 =0.7×0.7+0.3×0.8=0.73. In another preferred embodiment, the asymmetry between the first metal patch combination structure and the second metal patch combination structure is calculated as s=o30·wo31 ·r o32 +o33, where o30, o31 (o31>0), o32 (o32>0), and o33 are calculation coefficients obtained through pre-training. In this embodiment, the second size difference w=L6-L3=2.7mm, the preset second size difference threshold (3.86mm) is calculated for normalization, and the second size difference (normalized) is 2.7 / 3.86≈0.7; assuming that the absolute value of the angle between the vertical sides of the two "I"-shaped metal sheets is 10°, that is, the structural deviation value r=10, the preset structural deviation threshold (12.5°) is calculated for normalization, and the structural deviation value (normalized) is 10 / 12.5=0.8; the calculation coefficients o30=1.2, o31=1, o32=1, and o33=0 obtained through pre-training are calculated, and the asymmetry s=o30·w between the first metal patch combination structure and the second metal patch combination structure is calculated. o31 ·r o32 +o33=1.2×0.7×0.8+0=0.672.

[0063] Example A7: Calculate the asymmetry between the first metal patch combination structure and the second metal patch combination structure based on the first size difference, the second size difference and the structure deviation.

[0064] Specifically, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated based on the positive correlation between the first size difference l and the second size difference w and the structure deviation value r and the asymmetry of the first metal patch combination structure and the second metal patch combination structure. In a preferred embodiment, the asymmetry s of the first metal patch combination structure and the second metal patch combination structure is calculated as s = o34·l o35 +o36·w o37 +o38·r o39, where o34, o35 (o35>0), o36, o37 (o37>0), o38, o39 (o39>0) are calculation coefficients obtained by prior training. In this embodiment, the first size difference l = L1-L2 = 10.7mm, the preset first size difference threshold (18mm) is calculated for normalization, and the first size difference (normalized) is 10.7 / 18≈0.6; the second size difference w = L6-L3 = 2.7mm, the preset second size difference threshold (3.86mm) is calculated for normalization, and the second size difference (normalized) is 2.7 / 3.86≈0.7; assuming that two "I" shaped metal sheets are vertically connected, The absolute value of the angle between the straight lines is 10°, that is, the structural deviation value r = 10. The preset structural deviation threshold (12.5°) is calculated and normalized to obtain a structural deviation value (normalized) of 10 / 12.5 = 0.8. The calculation coefficients o34 = 0.5, o35 = 1, o26 = 0.3, o27 = 1, o28 = 0.2, and o29 = 1 obtained by prior training are used to calculate the asymmetry s = o34·l between the first metal patch combination structure and the second metal patch combination structure. o35 +o36·w o37 +o38·r o39 =0.5×0.6+0.3×0.7+0.2×0.8=0.67. In another preferred embodiment, the asymmetry between the first metal patch combination structure and the second metal patch combination structure is calculated as s=o40·l o41 w o42 ·r o43 +o44, where o40, o41 (o41>0), o42 (o42>0), o43 (o43>0), and o44 are calculation coefficients obtained by pre-training. In this embodiment, the first size difference l=L1-L2=10.7mm, the preset first size difference threshold (18mm) is calculated for normalization, and the first size difference (normalized) is 10.7 / 18≈0.6; the second size difference w=L6-L3=2.7mm, the preset second size difference threshold (3.86mm) is calculated for normalization, and the second size difference (normalized) is 2.7 / 3.86≈0.7; assuming that two "workers" The absolute value of the angle between the vertical edges of the metal sheet of the font is 10°, i.e., the structural deviation value r = 10. The preset structural deviation threshold (12.5°) is calculated and normalized to obtain a structural deviation value (normalized) of 10 / 12.5 = 0.8. The calculation coefficients o40 = 2, o41 = 1, o42 = 1, o43 = 1, and o44 = 0 obtained by prior training are used to calculate the asymmetry s = o40·l between the first metal patch combination structure and the second metal patch combination structure. o41 w o42 ·r o43+o44=2×0.6×0.7×0.8+0=0.672.

[0065] In such Figure 2 In the schematic diagram of the unit structure shown, the angle between the straight lines of the vertical sides of the two "I"-shaped metal sheets is 0, that is, the structural deviation value r = 0, and any one of Examples A1, A2 or A4 is used to calculate the asymmetry s of the first metal patch combination structure and the second metal patch combination structure.

[0066] In an exemplary embodiment, the deployment positions of the first metal patch combination structure and the second metal patch combination structure are obtained based on the degree of influence of the asymmetry of the first metal patch combination structure and the second metal patch combination structure on the phase difference of the transmitted wave and the functional relationship between the phase difference of the transmitted wave and the axial ratio, including the steps of:

[0067] Calculating a transmitted wave phase difference function according to the degree of influence of the asymmetry between the first metal patch combination structure and the second metal patch combination structure on the transmitted wave phase difference;

[0068] Calculate the axial ratio function based on the functional relationship between the phase difference of the transmitted wave and the axial ratio;

[0069] Substituting the transmitted wave phase difference function into the axial ratio function, we can get the correlation function between the axial ratio and the asymmetry.

[0070] Calculating the minimum value of the function related to the axial ratio and the asymmetry to obtain the target asymmetry of the first metal patch combination structure and the second metal patch combination structure;

[0071] The deployment positions of the first metal patch combination structure and the second metal patch combination structure are obtained according to the target asymmetry between the first metal patch combination structure and the second metal patch combination structure.

[0072] In this embodiment, the transmitted wave phase difference function is calculated based on the influence of the asymmetry degree of the first metal patch combination structure and the second metal patch combination structure on the transmitted wave phase difference. The transmitted wave phase difference function is calculated by training multiple times to obtain the transmitted wave phase difference corresponding to the asymmetry degree s of the first metal patch combination structure and the second metal patch combination structure. The transmitted wave phase difference is expressed as Then the phase difference function of the transmitted wave can be expressed as

[0073] Using the axial ratio (AR) to describe the transmitted wave can well demonstrate the excellent performance of the LTC polarization conversion of the structure. Therefore, four Stokes parameters are introduced: Where α in is the angle between the electric field direction of the incident electromagnetic wave and the x-axis. x , t y is the transmission coefficient of x-polarized wave and y-polarized wave, is the phase difference between the two transmitted waves.

[0074] Calculate the axial ratio function based on the functional relationship between the transmitted wave phase difference and the axial ratio

[0075] An AR value less than 3 dB is used to represent the LTC polarization conversion performance. The smaller the AR value, the stronger the LTC polarization conversion performance.

[0076] For ease of representation, the axial ratio function is written as

[0077] Substituting the transmitted wave phase difference function into the axial ratio function to obtain the axial ratio and asymmetry correlation function is expressed according to the transmitted wave phase difference function as follows: and the axial ratio function is written as The correlation function between the axial ratio and the asymmetry is obtained as AR=g(f(s)).

[0078] Calculate the minimum value of the function related to the axial ratio and the asymmetry AR = g(f(s)), and the asymmetry between the first metal patch combination structure and the second metal patch combination structure corresponding to the minimum AR value is the target asymmetry;

[0079] Adjust the deployment positions of the first metal patch combination structure and the second metal patch combination structure according to the target asymmetry between the first metal patch combination structure and the second metal patch combination structure and the calculation method of the asymmetry between the first metal patch combination structure and the second metal patch combination structure described in any one of Examples A1 to A7.

[0080] It should be noted that the adjustment of the first metal patch combination structure and the second metal patch combination structure should take into account the overall impact on the dielectric substrate, and each parameter has its own set threshold range.

[0081] According to another embodiment of the present invention, a design method for a dual-frequency polarization conversion electromagnetic induction unit is provided, which is characterized in that the flow chart is as follows: Figure 3 As shown, the steps include:

[0082] Step S01, calculating a transmitted wave phase difference function according to the degree of influence of the asymmetry of the first metal patch combination structure and the second metal patch combination structure on the transmitted wave phase difference;

[0083] Step S02: calculating the axial ratio function according to the functional relationship between the phase difference of the transmitted wave and the axial ratio;

[0084] Step S03: Substituting the transmitted wave phase difference function into the axial ratio function to obtain a correlation function between the axial ratio and the asymmetry;

[0085] Step S04: Calculate the minimum value of the function related to the axial ratio and the asymmetry, thereby obtaining the target asymmetry between the first metal patch combination structure and the second metal patch combination structure;

[0086] Step S05: adjusting the first metal patch combination structure and the second metal patch combination structure according to the target asymmetry of the first metal patch combination structure and the second metal patch combination structure and the relationship between the asymmetry and the structure of the first metal patch combination structure and the second metal patch combination structure, thereby obtaining a dual-frequency polarization conversion electromagnetic induction unit structure.

[0087] In this embodiment, according to the method described in the above embodiment for obtaining the deployment positions of the first metal patch combination structure and the second metal patch combination structure based on the degree of influence of the asymmetry of the first metal patch combination structure and the second metal patch combination structure on the phase difference of the transmitted wave and the functional relationship between the phase difference of the transmitted wave and the axial ratio, the first metal patch combination structure and the second metal patch combination structure are adjusted to obtain a dual-frequency polarization conversion electromagnetic induction unit structure.

[0088] In order to clarify the working mechanism of this electromagnetically induced transparency effect, numerical simulations were performed using CST Microwave Studio commercial electromagnetic simulation software. Figure 4 In the unit simulation performance graph shown, it can be clearly observed that when TE and TM waves are incident, two distinct EIT windows are generated, located at 8-8.4 GHz / 7.9-8.6 GHz and 8.4-9.3 GHz / 8.6-9 GHz, respectively. It is worth noting that the transmission coefficients corresponding to the transmission and reflection bands are not only equal at 8.5 GHz and 9.1 GHz, but also as high as 0.7 and 0.68, indicating that the metamaterial has the characteristics of low-loss transmission and that the transmission phase difference between the two transmitted electromagnetic waves is dominated by strong phase dispersion.

[0089] The optimal AR of the unit structure of this embodiment at 8.5GHz and 9.1GHz are 0.32dB and 0.12dB respectively. in =45°, showing nearly perfect LTC polarization conversion. In other words, perfect LTC polarization conversion can be observed in the EIT metamaterial.

[0090] According to another embodiment of the present invention, a dual-frequency polarization conversion electromagnetic induction transparent structure is provided. The dual-frequency polarization conversion electromagnetic induction units of the above embodiment are arranged at a predetermined period. The arrangement period of the dual-frequency polarization conversion electromagnetic induction units is greater than or equal to the side length of the dielectric substrate. In this embodiment, the arrangement period is equal to the side length P of the dielectric substrate, which is 35 mm.

[0091] Of course, those skilled in the art should realize that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. As long as they are within the scope of the present invention, any changes or modifications to the above embodiments will fall within the scope of protection of the present invention.

Claims

1. A dual-frequency polarization conversion electromagnetic induction unit, characterized in that: Including: A dielectric substrate, a first metal patch combination structure, and a second metal patch combination structure; the dielectric substrate is a square dielectric plate. The first metal patch combination structure is jointly composed of a "soil"-shaped metal sheet and an "I"-shaped metal sheet; the long horizontal sides of the "soil"-shaped metal sheet and the "I"-shaped metal sheet are parallel to each other, and the vertical sides are parallel to each other. The second metal patch combination structure is jointly composed of an "I"-shaped metal sheet and a "soldier"-shaped metal sheet; the long horizontal sides of the "I"-shaped metal sheet and the "soldier"-shaped metal sheet are parallel to each other, and the vertical sides are parallel to each other. The first metal patch combination structure and the second metal patch combination structure are distributed at the left and right ends or the upper and lower ends of the dielectric substrate, presenting an asymmetric distribution. The deployment positions of the first metal patch combination structure and the second metal patch combination structure are obtained based on the influence degree of the asymmetry of the first metal patch combination structure and the second metal patch combination structure on the transmission wave phase difference and the functional relationship between the transmission wave phase difference and the axial ratio, so as to achieve dual-frequency polarization conversion.

2. The dual-frequency polarization conversion electromagnetic induction unit according to claim 1, characterized in that: The dielectric substrate is composed of a layer of Rogers RO5880 dielectric layer; the material of the metal sheets in the first metal patch combination structure and the second metal patch combination structure is copper.

3. The dual-frequency polarization conversion electromagnetic induction unit according to claim 1, characterized in that: The length of the long horizontal side of the "soil"-shaped metal sheet is the same as the length of the long horizontal side of the "soldier"-shaped metal sheet; the length of the short horizontal side of the "soil"-shaped metal sheet is the same as the length of the short horizontal side of the "soldier"-shaped metal sheet; the length of the vertical side of the "soil"-shaped metal sheet is the same as the length of the vertical side of the "soldier"-shaped metal sheet.

4. The dual-frequency polarization conversion electromagnetic induction unit according to claim 1, characterized in that: The "I"-shaped metal sheet of the first metal patch combination structure has the same shape and size as the "I"-shaped metal sheet of the second metal patch combination structure; the lengths of each side of the "I"-shaped metal sheet are not the same as the lengths of each side of the "soil"-shaped metal sheet and the "soldier"-shaped metal sheet.

5. The dual-frequency polarization conversion electromagnetic induction unit according to claim 3, characterized in that: The asymmetry of the first metal patch combination structure and the second metal patch combination structure is calculated based on the positive correlation relationship between the length difference between the long horizontal side and the short horizontal side of the "soil"-shaped metal sheet and the "soldier"-shaped metal sheet and / or the length difference of the horizontal side of the "I"-shaped metal sheet and / or the length difference between the vertical side of the "soil"-shaped metal sheet and the "soldier"-shaped metal sheet and the vertical side of the "I"-shaped metal sheet and / or the angle between the straight lines where the vertical sides of the two "I"-shaped metal sheets are located and the degree of asymmetry.

6. The dual-frequency polarization conversion electromagnetic induction unit according to claim 5, characterized in that: The deployment positions of the first metal patch combination structure and the second metal patch combination structure are obtained based on the influence degree of the asymmetry of the first metal patch combination structure and the second metal patch combination structure on the transmission wave phase difference and the functional relationship between the transmission wave phase difference and the axial ratio, including: Calculating the transmission wave phase difference function based on the influence degree of the asymmetry of the first metal patch combination structure and the second metal patch combination structure on the transmission wave phase difference. Calculating the axial ratio function based on the functional relationship between the transmission wave phase difference and the axial ratio. Substituting the transmission wave phase difference function into the axial ratio function to obtain the axial ratio and asymmetry related function. Calculating the minimum value of the axial ratio and asymmetry related function, and thus obtaining the target asymmetry of the first metal patch combination structure and the second metal patch combination structure. Obtain the deployment positions of the first metal patch combination structure and the second metal patch combination structure according to the target asymmetry degree between the first metal patch combination structure and the second metal patch combination structure.

7. The dual-frequency polarization conversion electromagnetic induction unit according to claim 1, characterized in that: Preferably, the "I"-shaped metal sheets of the first metal patch combination structure and the "I"-shaped metal sheets of the second metal patch combination structure are symmetrically distributed along the diagonal of the dielectric substrate.

8. The dual-frequency polarization conversion electromagnetic induction unit according to claim 1, characterized in that: Preferably, the length of the long horizontal side of the "T"-shaped metal sheet and the length of the long horizontal side of the "T"-shaped metal sheet are 16 mm, the length of the short horizontal side is 5.3 mm, and the length of the vertical side is 5.8 mm; the length of the long horizontal side of the "I"-shaped metal sheet is 9 mm, the length of the short horizontal side is 3.1 mm, and the length of the vertical side is 8.5 mm; the side length of the dielectric substrate is 35 mm, and the thickness of the dielectric substrate is 1 mm.

9. A design method for a dual-frequency polarization conversion electromagnetic induction unit according to any one of claims 1 to 8, characterized in that: Include the steps: Calculate the transmission wave phase difference function according to the influence degree of the asymmetry degree between the first metal patch combination structure and the second metal patch combination structure on the transmission wave phase difference; Calculate the axial ratio function according to the functional relationship between the transmission wave phase difference and the axial ratio; Substitute the transmission wave phase difference function into the axial ratio function to obtain the axial ratio and asymmetry degree correlation function; Calculate the minimum value of the axial ratio and asymmetry degree correlation function to obtain the target asymmetry degree between the first metal patch combination structure and the second metal patch combination structure; Adjust the first metal patch combination structure and the second metal patch combination structure according to the target asymmetry degree between the first metal patch combination structure and the second metal patch combination structure and the relationship between the asymmetry degree of the first metal patch combination structure and the second metal patch combination structure and the structure, so as to obtain the dual-frequency polarization conversion electromagnetic induction unit structure.

10. A dual-frequency polarization conversion electromagnetically induced transparent structure, characterized in that: It is composed of the dual-frequency polarization conversion electromagnetic induction units described in any one of claims 1-8 arranged according to a preset period, and the arrangement period of the dual-frequency polarization conversion electromagnetic induction units is greater than or equal to the side length of the dielectric substrate.

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