Design method and device for multi-frequency transparent transmission type surface-mounted metasurface structure

Abstract

The invention relates to the field of surface-mounted metasurface structure design, in particular to a design method and device for a multi-frequency transparent transmission type surface-mounted metasurface structure, and the method comprises the steps: representing a multi-layer structure of a glass surface-mounted metasurface through a cascade transmission matrix; wherein the metasurface comprises a metal layer and a dielectric layer; a corresponding transmission coefficient is calculated by using the represented cascade transmission matrix, and a theoretical optimal transmission coefficient of a target frequency band under the structure is obtained by adjusting the dielectric constant and the thickness of a metasurface dielectric layer and the equivalent impedance of a metasurface metal layer to determine an initial structure and a parameter change interval of a to-be-optimized metasurface unit; simulating to obtain a transmission coefficient under the initial structure of the metasurface; and based on the transmission coefficient under the initial structure of the metasurface, taking a theoretical optimal transmission coefficient as an optimization target, and adopting a quasi-Newton algorithm to optimize metasurface design to obtain a metasurface structure corresponding to the optimal transmission coefficient. Compared with the prior art, the invention has the advantages of greatly and stably improving the transmission performance of multiple frequency bands and the like.

Description

Technical Field

[0001] The present invention relates to the field of surface mount metasurface structure design, and in particular to a design method and device for a multi-frequency transparent transmission type surface mount metasurface structure for 5G or 6G communications. Background Art

[0002] With the rise of global low-carbon emission reduction, Low-E glass (Low-Emissivity, low-radiation glass) is widely used in building curtain walls and automotive glass. Low-E glass is often composed of two glass substrates with a vacuum gap in the middle and a metal coating on the inner surface of the substrate. This structure shows excellent efficiency in terms of thermal insulation and sound insulation. However, in 5G and / or 6G communications, due to the shorter wavelength of electromagnetic waves, the transmission loss of electromagnetic waves through window glass increases significantly. This change weakens the intensity of electromagnetic signals that penetrate the window into the room, thereby affecting the signal coverage of outdoor base stations to indoor areas.

[0003] In order to improve the transmittance of electromagnetic signals of energy-saving window glass such as Low-E glass and enhance indoor signal access, the problem of glass blocking signals can be solved by introducing metasurfaces. The traditional metasurface unit structure design method finds the required design by parametrically defining the structure and scanning the parameters, and only optimizes within limited parameters and intervals, making it difficult to find the optimal transmission system performance. To solve the above problems, existing technologies usually introduce optimization algorithms or machine learning to optimize metasurface design.

[0004] After searching, the Chinese invention patent application publication number CN117668954A discloses a design method and system for a metasurface bandpass filter resonant structure, including using simulation software to generate data to train a VAE (Variational Autoencoder) model; inputting the target transmission spectrum into the VAE decoder to generate and screen candidate unit structures; using the candidate unit structure as the initial value, and combining the prediction network and numerical simulation through a global optimization algorithm to obtain the optimal unit structure. However, this method does not take into account the needs of multiple frequency bands and is difficult to meet the actual application requirements of signal transmission in multiple frequency bands in 5G / 6G communications. In addition, this design method does not limit the proportion of metal in the metasurface, resulting in the inability to effectively guarantee light transmittance, and is not suitable for modern glass windows that require high light transmittance.

[0005] After searching, a design method, device, equipment and storage medium of electromagnetic glass are disclosed in the invention patent application publication number CN117556716A. This method designs a super surface by etching the metal coating inside the glass, which has good light transmission performance. However, this design method is limited by the integrated manufacturing with glass and cannot be directly applied to window glass that has been put into use, which limits its application in the renovation of existing buildings or equipment.

[0006] How to improve the transmittance of Low-E glass to multi-frequency electromagnetic signals has become a technical problem that needs to be solved. Summary of the invention

[0007] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a design method for a multi-frequency transparent transmission type surface mount metasurface structure.

[0008] The purpose of the present invention can be achieved by the following technical solutions: According to one aspect of the present invention, a method for designing a multi-frequency transparent transmission type surface mount metasurface structure is provided, the method comprising the following steps: Step 1, using a cascaded transmission matrix to characterize the multilayer structure of a glass surface mounted metasurface; wherein the metasurface includes a metal layer and a dielectric layer; Step 2, using the conversion relationship between the characterized cascade transmission matrix and the scattering matrix, the corresponding transmission coefficient is calculated, and the theoretical optimal transmission coefficient of the target frequency band under the structure is obtained by adjusting the dielectric constant and thickness of the metasurface dielectric layer and the equivalent impedance of the metasurface metal layer; Step 3, determining the initial structure and parameter variation range of the metasurface unit to be optimized, and simulating to obtain the transmission coefficient under the initial structure of the metasurface; Step 4: Based on the transmission coefficient of the initial structure of the metasurface, taking the theoretical optimal transmission coefficient as the optimization target, within the given parameter variation range, the quasi-Newton algorithm is used to optimize the metasurface design to obtain the metasurface structure corresponding to the optimal transmission coefficient.

[0009] Preferably, when the glass is Low-E glass, the multilayer structure of the Low-E glass surface-mounted super-surface includes a Low-E glass portion and a super-surface portion, wherein the Low-E glass portion includes a first glass layer, a coating layer, a vacuum layer, and a second glass layer arranged in sequence, and the super-surface is mounted on the second glass layer; The metasurface includes metal layers and dielectric layers arranged at intervals, including: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, ..., the n-1th dielectric layer and the nth metal layer are arranged in sequence, wherein n is greater than 1; Or the metasurface includes metal layers and dielectric layers arranged at intervals, including: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer...the n-1th metal layer, the n-1th dielectric layer, the nth metal layer and the nth dielectric layer are arranged in sequence; wherein n is greater than or equal to 1.

[0010] More preferably, the transmission matrix of the metasurface metal layer is characterized as:

[0011] in, Z ms is the equivalent impedance; Coatings in Low-E Glass It is expressed as:

[0012] in, Z coating Represents the equivalent square resistance of the coating; The transmission matrix of other layers of Low-E glass surface mounted ultra-surface glass is defined as follows:

[0013]

[0014] in, d n For the n The thickness of the dielectric layer, For the n The wave impedance of the layer medium, η 0 is the air wave impedance, For the n The wave number of the layer medium, For the n The dielectric constant of the layer medium relative to air, For the n The magnetic permeability of the layer medium relative to air, f is the frequency of the electromagnetic wave, c is the speed of light in a vacuum; Therefore, for the surface-mounted meta-glass with L target frequency bands, when the last layer is a metal layer, the multi-layer structure is characterized by the cascade of transmission matrices:

[0015] For surface-mounted meta-glass with L target frequency bands, when the last layer is a non-metallic layer, the multi-layer structure is characterized by the cascade of transmission matrices:

[0016] in, Tglass1 、T coating 、T vacuum 、T glass2 、T MS1 、T PMMA1 、T MS2 、T PMMA2 、 They respectively represent the transmission matrices of the first glass layer, coating layer, vacuum layer and second glass layer, first metal layer, first dielectric layer, second metal layer, second dielectric layer...nth metal layer, nth dielectric layer, where L is the number of frequency bands and L is greater than 2.

[0017] Preferably, assuming that the cascade transmission matrix of the surface-mounted meta-glass is The scattering matrix is , then the corresponding transmission coefficient The calculation of is as follows:

[0018] in, η 0 is the wave impedance of air.

[0019] Preferably, the initial structure of the metasurface metal layer adopts a circular ring structure, and the circular ring structure of the metal layer depends on the equivalent transmission line circuit of the glass surface-mounted metasurface. If the equivalent transmission line circuit of a metal layer transmission matrix is ​​a parallel structure, the corresponding initial structure is a double circular ring structure; if the equivalent transmission line circuit of a metal layer transmission matrix is ​​a series structure, the corresponding initial structure is a single circular ring structure.

[0020] Preferably, the structure of the supersurface metal layer is symmetrical about the center of the supersurface unit.

[0021] Preferably, the circular ring of the metasurface metal layer is equally divided into eight short microstrip lines, and independent parameters are used to define their positions and lengths and widths. The corresponding optimization space is the position, length and width of each metal layer circular ring on the short microstrip line and the thickness of each dielectric layer.

[0022] Preferably, obtaining the metasurface structure corresponding to the optimal transmission coefficient in step 4 includes: Based on the transmission performance of the initial structure, the theoretical optimal transmission coefficient is used as the optimization target, a convergence threshold is set, and an initial parameter is determined. As a starting point for the algorithm to start optimizing and select a matrix ,by Optimize for direction; Based on current point With the previous point The gradient information of to update the matrix , determine the next optimization direction, update The expression is:

[0023] in, k To optimize the number of times, ; is the transmission coefficient exist x = The first derivative of ; is the transmission coefficient exist x = The first derivative of ; If the difference between the transmission coefficient of the current point and the set optimization target is greater than the preset threshold, the termination condition is not met, and the next round of optimization will continue; if the termination condition is met, it is considered that the algorithm has converged to the optimal solution, the optimization is stopped, and the hypersurface structure of the optimal point is output.

[0024] Preferably, the dielectric material of the dielectric layer is PMMA.

[0025] According to another aspect of the present invention, an electronic device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the method described above is implemented when the processor executes the program.

[0026] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses a cascade transmission matrix to characterize the multilayer structure of the glass surface mounted metasurface, derives the theoretical optimal transmission performance of the target frequency band, and optimizes the design with the theoretical optimal transmission performance as the optimization target. After the metasurface designed for the glass surface is mounted, the transmission capacity of electromagnetic signals at multiple frequency bands is close to the theoretical optimal transmission capacity compared to glass.

[0027] (2) The metal layer of the present invention adopts a simple circular ring structure design. The circular ring of each metal layer is equally divided into eight short microstrip lines, and its position, length and width are defined by independent parameters. The quasi-Newton algorithm is used to optimize the design of the metasurface suitable for multiple target frequency bands in the optimization space, and different frequency bands are optimized and adjusted simultaneously, thereby greatly improving the transmission performance of the Low-E glass at multiple target frequency points.

[0028] (3) The design method of the present invention has stable performance when the electromagnetic signal is incident at an incident angle of 0-60°, and takes into account the advantages of high transmittance and high angle stability.

[0029] (4) The surface-mounted metasurface designed by the present invention is different from the integrated manufacturing process of window glass and is easy to deploy. The metasurface design can be directly surface-mounted on the installed building window glass and can be compatible with 5G CPE or 6G RIS to further improve indoor signal coverage. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic flow chart of a method for designing a three-band transparent transmission type surface mount metasurface based on Low-E glass in the present invention; Figure 2 It is a schematic diagram of the integrated structural model of Low-E glass and the three-band transparent transmission type surface mount metasurface in Example 2 of the present invention; Figure 3 1 is a schematic diagram of an equivalent transmission line circuit of a multilayer structure of a Low-E glass surface mounted triple-frequency metasurface in Example 2 of the present invention; Figure 4 1 is a schematic diagram of the optimal transmission performance curve of the Low-E glass surface mounted triple-frequency metasurface at the target frequency point in Example 2 of the present invention; Figure 5 is a schematic diagram of the initial shape of the hypersurface unit to be optimized in Example 2 of the present invention; Figure 6 Schematic diagram of the double-ring structure of the metal layer of the super-surface unit to be optimized in Example 2 of the present invention; Figure 7 Schematic diagram of a single circular ring structure of a metal layer of a super surface unit to be optimized in Example 2 of the present invention; Figure 8 It is a schematic diagram of the optimal design structure of the three-band transparent transmission type surface-mount metasurface unit in Example 2 of the present invention; Fig. 9 This is a schematic diagram of the optimal first metal layer structure of the triple-band transparent transmission type surface mount metasurface unit in Example 2 of the present invention; Fig.10 This is a schematic diagram of the optimal second metal layer structure of the triple-band transparent transmission type surface mount metasurface unit in Example 2 of the present invention; Fig.11 This is a schematic diagram of the optimal third metal layer structure of the triple-band transparent transmission type surface mount metasurface unit in Example 2 of the present invention; Fig.12 It is a diagram showing the penetration performance of the triple-frequency metasurface to the incident signal before and after being attached to the Low-E glass in Example 2 of the present invention; Fig.13 Schematic diagram of the integrated structural model of Low-E glass and four-band transparent transmission type surface mount metasurface in Example 3 of the present invention; Fig.14 This is a schematic diagram of an equivalent transmission line circuit of a multilayer structure of a Low-E glass surface mounted quad-frequency metasurface in Example 3 of the present invention; Fig.15 1 is a schematic diagram of the optimal transmission performance curve of the Low-E glass surface mounted quad-frequency metasurface at the target frequency point in Example 3 of the present invention; Fig.16 is a schematic diagram of the initial shape of the hypersurface unit to be optimized in Example 3 of the present invention; Fig.17 Schematic diagram of the double-ring structure of the metal layer of the super-surface unit to be optimized in Example 3 of the present invention; Fig.18 Schematic diagram of a single circular ring structure of a metal layer of a super surface unit to be optimized in Example 3 of the present invention; Fig.19 This is a schematic diagram of the optimal design structure of the quad-band transparent transmission type surface mount metasurface unit in Example 3 of the present invention; Fig. 20 This is a schematic diagram of the optimal first metal layer structure of a quad-band transparent transmission type surface mount metasurface unit in Example 3 of the present invention; Fig.21 This is a schematic diagram of the optimal second metal layer structure of the quad-band transparent transmission type surface mount metasurface unit in Example 3 of the present invention; Fig. 22 This is a schematic diagram of the optimal third metal layer structure of the quad-band transparent transmission type surface mount metasurface unit in Example 3 of the present invention; Fig.23 This is a schematic diagram of the optimal fourth metal layer structure of the quad-band transparent transmission type surface mount metasurface unit in Example 3 of the present invention; Fig.24 It is a diagram showing the penetration performance of the quad-frequency metasurface to the incident signal before and after being attached to the Low-E glass in Example 3 of the present invention; In the drawings, 1 is a first metal layer, 2 is a first dielectric layer, 3 is a second metal layer, 4 is a second dielectric layer, 5 is a third metal layer, 6 is a third dielectric layer, and 7 is a fourth metal layer. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0032] Example 1 This embodiment relates to a design method for a multi-frequency transparent transmission type surface-mounted metasurface structure, which is oriented to 5G / 6G communications. After the glass surface is mounted with the metasurface designed by the present invention, its electromagnetic signal transmission ability can be improved at multiple target frequency points relative to glass. In addition, the designed metasurface takes into account the advantages of high transmittance and high angle stability, and can be directly surface-mounted on the installed building window glass to improve the window glass's transmission ability at multiple target frequency bands and enhance indoor signal access.

[0033] like Figure 1 , the method comprises the following steps: The multilayer structure of the glass surface-mounted metasurface is characterized by the transmission matrix method. Each layer of the structure is equivalent to a transmission line circuit, and the scattering problem of the incident electromagnetic wave is analyzed. Using the transmission matrix and scattering matrix The conversion relationship between them is used to calculate the corresponding transmission coefficient :

[0034] By adjusting the dielectric constant and thickness of the metasurface dielectric layer and the equivalent impedance of the metasurface metal layer, the theoretical optimal transmission coefficient of the glass surface-mounted metasurface structure at the target frequency band is analyzed; Determine the initial structure and parameter variation range of the metasurface unit to be optimized, and simulate to obtain the transmission coefficient under the initial structure of the metasurface unit; Based on the transmission coefficient of the initial structure of the metasurface unit, the theoretical optimal transmission coefficient is obtained by the transmission matrix method. To optimize the target, the quasi-Newton algorithm is used to optimize the metasurface design within a given parameter variation range to obtain the metasurface unit that is closest to the theoretical optimal transmission coefficient.

[0035] The transmission matrix of each layer of surface mounted meta-glass is defined as:

[0036]

[0037] in, d n For the n The thickness of the layer medium, For the n The wave impedance of the layer medium, η 0 is the air wave impedance, For the n The wave number of the layer medium, For the n The dielectric constant of the layer medium relative to air, For the nThe magnetic permeability of the layer medium relative to air, f is the frequency of the electromagnetic wave, c is the speed of light in vacuum; the equivalent impedance of the metasurface metal layer Z ms , its transmission matrix can be characterized as:

[0038] The multilayer structure of surface mounted meta-glass can be characterized as a cascade of transmission matrices:

[0039]

[0040] By adjusting the equivalent impedance and material parameters of the metasurface metal layer, including the dielectric constant and thickness of the adjustable layer structure, the theoretical optimal transmission performance of the glass surface mounted metasurface in the target frequency band is analyzed and obtained.

[0041] The process of the quasi-Newton algorithm includes: Taking the variation range of the geometric shape, size and material parameters of the metasurface unit as the optimization space, setting the optimization target of the corresponding frequency band and the corresponding convergence threshold, and determining an initial parameter As a starting point for the algorithm to start optimizing and select a matrix ,by Optimize for direction; Based on current point With the previous point The gradient information of to update the matrix , determine the next optimization direction, update The expression is:

[0042] in, k To optimize the number of times, ; is the transmission coefficient exist x = The first derivative of ; is the transmission coefficient exist x = The first derivative of .

[0043] If the difference between the function value of the current optimization point and the set optimization target is greater than the preset threshold, the termination condition is not met, and the optimization calculation step is returned to the next round of optimization; if the termination condition is met, it is considered that the algorithm has converged to the optimal solution, and the optimization can be stopped to output the optimal design.

[0044] The method in this embodiment is applicable to any glass design with a known structure and a multi-frequency transparent transmission type surface mount metasurface, such as Low-E glass, double-layer white glass, single-layer glass, etc.

[0045] Example 2 This embodiment relates to a design method for a multi-frequency transparent transmission type surface mount metasurface structure, and designs a three-frequency transmission type surface mount metasurface structure. Here, Low-E glass is taken as an example, but the design method is also applicable to other glasses with known structures. Figure 1 , the method comprises the following steps: Step 101: Facilitate the transfer matrix representation such as Figure 2 The multi-layer structure of the Low-E glass surface-mounted metasurface shown in the figure; wherein the Low-E glass portion is located outdoors and the metasurface portion is located indoors. The Low-E glass portion includes a first glass layer, a coating layer, a vacuum layer, and a second glass layer in sequence. The metasurface is mounted on the second glass layer. Each metasurface unit includes a metal layer and a dielectric layer, wherein the metal layer includes: a first metal layer (MS1), a second metal layer (MS2), and a third metal layer (MS3), and the dielectric layer includes: a first dielectric layer (PMMA1) and a second dielectric layer (PMMA2); the first metal layer, the first dielectric layer, the second metal layer, the second dielectric layer, and the third metal layer are arranged in sequence from left to right.

[0046] The multi-layer structure of the Low-E glass surface mounted triple-band metasurface can be characterized as a cascade of transmission matrices:

[0047] in T glass1 、T coating 、T vacuum 、T glass2 、T MS1 、T PMMA1 、T MS2 、T PMMA2 、 and T MS3 They represent the transmission matrices of the first glass layer, coating layer, vacuum layer, and second glass layer, the first metal layer (MS1), the first dielectric layer (PMMA1), the second metal layer (MS2), the second dielectric layer (PMMA2), and the third metal layer (MS3), respectively. The equivalent transmission line circuit of the Low-E glass surface-mounted metasurface is shown in Figure 3 shown.

[0048] The transmission matrix of each layer structure is defined as:

[0049]

[0050] in, d n is the thickness of the medium, is the wave impedance of the medium, η 0 is the air wave impedance, is the dielectric constant of the medium relative to air, is the magnetic permeability of the medium relative to air, f is the frequency of the electromagnetic wave, c is the speed of light in a vacuum, the thickness of the first and second glass layers d glass1 =d glass2 =6 cm, the dielectric constant of glass relative to air is 6.98. The thickness of the vacuum layer d vacuum =12 mm, the dielectric constant of vacuum relative to air is 1. The dielectric constant of medium PMMA relative to air is 3.8, and the thickness of the first dielectric layer (PMMA1) and the second dielectric layer (PMMA2) are d 1. d 2. The magnetic permeability of glass, vacuum and PMMA relative to air is 1, and the wave impedance of air is η 0 It is 377.

[0051] Coatings in Low-E Glass Expressed as

[0052] in Z coating = 4 Ω / m 2 Represents the equivalent square resistance of the coating.

[0053] The equivalent impedance of the metasurface metal layer Z ms , its transmission matrix can be expressed as:

[0054] Step 102: Analyze the characterized cascade transmission matrix to obtain the theoretical optimal transmission performance of the target frequency bands (3.5 GHz, 4.9 GHz, and 6.2 GHz) under the structure.

[0055] Using the transfer matrix The transmission coefficient at this time is calculated by the conversion relationship between the scattering matrix :

[0056] By adjusting the thickness of the dielectric layers PMMA1 and PMMA2 , And the equivalent impedance of the metasurface metal layer Z MS1 , Z MS2 , Z MS3 , analyze the theoretical optimal transmission performance of the glass surface after the metasurface is attached at the target frequency. Figure 4 The figure shows the optimal transmission performance curve at the target frequency bands of 3.5GHz, 4.9GHz and 6.2GHz when the metasurface is attached to the glass surface. The signal strength at 3.5GHz, 4.9GHz and 6.2GHz is improved by 10.1dB, 10.75dB and 12.18dB respectively.

[0057] Step 103: Determine the initial structure and parameter variation range of the hypersurface unit to be optimized.

[0058] Establish a simple regular pattern as the metal layer structure of the metasurface. Considering the need for transmittance, a circular ring structure with good transmittance is selected. The initial structure of the metasurface unit to be optimized is as follows: Figure 5 As shown, the metasurface to be optimized is composed of a metal layer and a dielectric layer, the metal layer includes: a first metal layer 1, a second metal layer 3 and a third metal layer 5, and the dielectric layer includes: a first dielectric layer 2 and a second dielectric layer 4; the first metal layer 1, the first dielectric layer 2, the second metal layer 3, the second dielectric layer 4 and the third metal layer 5 are arranged in sequence from left to right; The initial structure of the first metal layer and the second metal layer is the same, using Figure 6 The double ring structure is shown. The initial structure of the third metal layer is as follows Figure 7 In the single ring structure shown, the rings of each metal layer are equally divided into eight short microstrip lines (for double ring structure: 1a~8a of the inner ring, 1b~8b of the outer ring; for single ring structure: 1a~8a of the ring), and their positions, lengths and widths are defined using independent parameters. The optimization space is the position, length and width of each layer of rings on the short microstrip line, as well as the thickness of the dielectric layers PMMA1 and PMMA2. , .

[0059] Step 104: Based on the transmission performance of the initial shape, the theoretical optimal transmission coefficient in step S102 is used. To optimize the target, a quasi-Newton algorithm is used to optimize the design of the triple-frequency metasurface within the optimization space determined in step S103.

[0060] The optimization targets of the target frequencies 3.5 GHz, 4.9 GHz, and 6.2 GHz are set to 10.1 dB, 10.75 dB, and 12.18 dB, and the convergence threshold is set to 3 dB. The oblique incidence of 45° is used as the design benchmark to take into account the performance of the metasurface in the oblique incidence range of 0°-60°. As a starting point for algorithm optimization, choose the identity matrix ,by Optimize for direction; Based on current point With the previous point The gradient information of to update the matrix , determine the next optimization direction, update The expression is:

[0061] If the difference between the function value of the current optimization point and the set optimization target is greater than the preset threshold of 3dB, the termination condition is not met, and the optimization calculation step is returned to the next round of optimization; if the termination condition is met, it is considered that the algorithm has converged to the optimal solution, the optimization can be stopped, and the optimal design is output. The optimal design is as follows Figure 8 As shown, Fig. 9 is the structure of the first metal layer, Fig.10 is the structure of the second metal layer of the unit, Fig.11 This is the structure of the third metal layer.

[0062] The present embodiment is further described below based on simulation results: like Fig.12 , the designed three-band transparent transmission surface-mounted metasurface based on Low-E glass is simulated. The electromagnetic signal passes through the Low-E glass and the metasurface from the outdoor to the indoor. Compared with the Low-E glass without the three-band metasurface, when the electromagnetic signal is incident normally (the incident angle is 0°), there are 9.11dB, 7.41dB and 8.03 dB gains at the target frequencies of 3.5GHz, 4.9GHz and 6.2GHz. When the electromagnetic signal is incident at 30°, there are 8.25dB, 8.60dB and 8.52 dB gains at the target frequencies of 3.5GHz, 4.9GHz and 6.2GHz. When the electromagnetic signal is incident at 60°, there are 8.40 dB, 9.26 dB and 10.26 dB gains at the target frequencies of 3.5GHz, 4.9GHz and 6.2GHz. The designed metasurface can stably resist electromagnetic waves incident at angles of 0°-60° in the 3.5GHz, 4.9GHz and 6.2GHz frequency bands. Its gain relative to Low-E glass always remains at 7.4-10.26 dB, and it has a transmittance of approximately 86.3%.

[0063] The side length of the triple-frequency metasurface unit is p, the metal layer structure is a circular ring, the structures of the first metal layer and the second metal layer both adopt a double circular ring structure, and the third metal layer adopts a single circular ring structure; the metal layer structure is symmetrical about the center of the unit, achieving high angular stability; the metal layer is attached to the dielectric layer and has a thickness of 50 microns. The first dielectric layer and the second dielectric layer have the same shape and size. The dielectric material is PMMA with a thickness of 3 mm.

[0064] The triple-band transmission metasurface is surface-mounted on Low-E glass and is suitable for 5G / 6G frequency bands of N78, N79 and 6.2GHz.

[0065] Example 3 This embodiment relates to a design method for a multi-frequency transparent transmission type surface mount metasurface structure, and designs a quad-frequency transparent transmission type surface mount metasurface for 5G / 6G communication. The steps are similar to those of Embodiment 2: It is useful to characterize the transfer matrix as Fig.13 The multilayer structure of the Low-E glass surface mounted metasurface shown in FIG. 1 ; the equivalent transmission line circuit of the Low-E glass surface mounted metasurface shown in FIG. Fig.14 As shown in the figure, the multi-layer structure of the Low-E glass surface mounted quad-band metasurface can be characterized as a cascade of transmission matrices:

[0066] in T glass1 、T coating 、T vacuum 、T glass2 、T MS1 、T PMMA1 、T MS2 、T PMMA2 、T MS3 、T PMMA3 、 and T MS4 They represent the transmission matrices of the first glass layer, coating layer, vacuum layer, and second glass layer, the first metal layer (MS1), the first dielectric layer (PMMA1), the second metal layer (MS2), the second dielectric layer (PMMA2), the third metal layer (MS3), the third dielectric layer (PMMA3), and the fourth metal layer (MS4). The equivalent transmission line circuit of the Low-E glass surface-mounted metasurface is shown in Figure 1. Fig.14 shown.

[0067] The characterized cascade transmission matrix was analyzed to obtain the optimal transmission performance of the target frequencies of 3.5 GHz, 4.9 GHz, 6.2 GHz and 6.7 GHz under this structure: by adjusting the thickness of the dielectric layers PMMA1, PMMA2 and PMMA3 , And the equivalent impedance of the metasurface metal layer Z MS1 , Z MS2 , Z MS3 , Z MS4 , analyze the theoretical optimal transmission performance of the glass surface after the metasurface is attached at the target frequency. Fig.15 Shown is the optimal transmission performance curve at the target frequency bands of 3.5GHz, 4.9GHz, 6.2GHz and 6.7GHz when the metasurface is attached to the glass surface, with improvements of 10.23dB, 10.30dB, 9.03dB and 10.11dB at 3.5GHz, 4.9GHz, 6.2GHz and 6.7GHz respectively.

[0068] Determine the initial structure and parameter variation range of the hypersurface unit to be optimized: The initial structure of the hypersurface unit to be optimized is as follows: Fig.16 As shown, the metasurface to be optimized is composed of a metal layer and a dielectric layer, the metal layer includes: a first metal layer 1, a second metal layer 3, a third metal layer 5 and a fourth metal layer 7, and the dielectric layer includes: a first dielectric layer 2, a second dielectric layer 4 and a third dielectric layer 6; the first metal layer 1, the first dielectric layer 2, the second metal layer 3, the second dielectric layer 4, the third metal layer 5, the third dielectric layer 6 and the fourth metal layer 7 are arranged in sequence from left to right.

[0069] The initial structures of the first and fourth metal layers are the same, using Fig.18 The single ring structure is shown. The initial structure of the second and third metal layers is the same. Fig.17 It is a double ring structure. The rings of each metal layer are equally divided into eight short microstrip lines (double ring structure: 1a~8a of the inner ring, 1b~8b of the outer ring; single ring structure: 1a~8a of the ring), and independent parameters are used to define their positions and lengths and widths. The optimization space is the position, length and width of each ring on the short microstrip line and the thickness of the dielectric layers PMMA1, PMMA2 and PMMA3. , , .

[0070] Based on the transmission performance of the initial shape, the theoretical optimal transmission coefficient To optimize the target, the quasi-Newton algorithm is used to optimize the design of the quad-frequency metasurface in the optimization space.

[0071] The optimization targets of the target frequencies 3.5 GHz, 4.9 GHz, 6.2 GHz and 6.7 GHz were set to 10.23 dB, 10.30 dB, 9.03 dB and 10.11 dB, and the convergence threshold was set to 3 dB. The design benchmark was 45° oblique incidence, taking into account the performance of the metasurface in the incident angle range of 0°- 60°. The initial parameters were As the starting point for the algorithm optimization, choose the identity matrix ,by Optimize for direction; Based on current point With the previous point The gradient information of to update the matrix , determine the next optimization direction; If the difference between the function value of the current optimization point and the set optimization target is greater than the preset threshold of 3dB, the termination condition is not met, and the optimization calculation step is returned to the next round of optimization. If the termination condition is met, it is considered that the algorithm has converged to the optimal solution, and the optimization can be stopped and the optimal design is output. The optimal design is as follows: Fig.19 ~ Fig.23 As shown, Fig. 20 is the structure of the first metal layer, Fig.21 is the structure of the second metal layer, Fig. 22 is the structure of the third metal layer, Fig.23 This is the structure of the fourth metal layer.

[0072] The present embodiment is further described below based on simulation results: See also Fig.24 , the designed four-band transmission type transparent surface-mounted metasurface based on Low-E glass is simulated. The electromagnetic signal passes through the Low-E glass and the metasurface from the outdoor to the indoor. Compared with the Low-E glass without the four-band metasurface, when the electromagnetic signal is incident normally, there are 7.40dB, 6.81dB, 7.38dB and 8.50dB gains at the target frequencies of 3.5GHz, 4.9GHz, 6.2GHz and 6.7GHz. When the electromagnetic signal is incident at 30°, there are 8.96dB, 7.84dB, 7.33dB and 9.86dB gains at the target frequencies of 3.5GHz, 4.9GHz, 6.2GHz and 6.7GHz. When the electromagnetic signal is incident at 60°, there are 10.01dB, 7.69dB, 8.74dB and 8.53dB gains at the target frequencies of 3.5GHz, 4.9GHz, 6.2GHz and 6.7GHz, as shown in Figure 2. Fig.13The designed metasurface can stably resist electromagnetic waves incident at angles of 0°-60° in the 3.5GHz, 4.9GHz, 6.2GHz and 6.7GHz frequency bands. Its gain relative to Low-E glass is always maintained at 6.8–10.01 dB, and it has a transmittance of about 82.5%.

[0073] The side length of the quad-frequency metasurface unit is p, the metal layer structure is a circular ring structure, the shapes of the first metal layer, the second metal layer and the third metal layer all adopt a double circular ring structure, and the fourth metal layer adopts a single circular ring structure; the metal layer structure is symmetrical about the center of the unit, achieving high angular stability; the metal layer is attached to the dielectric layer and has a thickness of 50 microns. The first and second dielectric layers have the same shape and size, the dielectric material is PMMA, and the thickness is 0.8 mm. The dielectric material of the third dielectric layer is PMMA, and the thickness is 3 mm.

[0074] The quad-band transmission metasurface is surface-mounted on Low-E glass and is suitable for 5G / 6G frequency bands of N78, N79, 6.2GHz and 6.7GHz.

[0075] The high angular stability of the multi-frequency metasurface means that when the electromagnetic wave is incident at an angle of 0-60°, the transmission-type multi-frequency metasurface can improve the glass's ability to transmit electromagnetic waves, and the multi-frequency metasurface has a high transmittance of more than 80%.

[0076] This embodiment also relates to a design method for a multi-frequency transparent transmission type surface mount metasurface structure, and designs a transparent transmission type surface mount metasurface for L target frequency bands of 5G / 6G communication, where L>2. The metasurface to be optimized is composed of a metal layer and a dielectric layer, the metal layer includes: a first metal layer, a second metal layer...nth metal layer, the dielectric layer includes: a first dielectric layer, a second dielectric layer and n-1th dielectric layer; the first metal layer, the first dielectric layer, the second metal layer, the second dielectric layer...n-1th metal layer, the n-1th dielectric layer and the nth metal layer are arranged in sequence, and n is greater than 1.

[0077] In addition, the metasurface to be optimized is composed of a metal layer and a dielectric layer, and its structure may also be: the metal layer includes: a first metal layer, a second metal layer...an nth metal layer, and the dielectric layer includes: a first dielectric layer, a second dielectric layer and an nth dielectric layer; the first metal layer, the first dielectric layer, the second metal layer, the second dielectric layer...an n-1th metal layer, an n-1th dielectric layer, an nth metal layer and an nth dielectric layer are arranged in sequence, and n is greater than or equal to 1.

[0078] The metal layer structure is a circular ring structure, and the circular ring structure of the metal layer depends on the equivalent transmission line circuit of the glass surface mounted metasurface, such as Figure 3 and Fig.14 , if the transmission matrix of the i-th metal layer T MSiThe equivalent transmission line circuit is in parallel, and the corresponding initial structure is a double ring structure. If the transmission matrix of the i-th metal layer in the figure T MSi The equivalent transmission line circuit is a series connection, and the corresponding initial structure is a single circular ring structure. In addition to the circular structure, the metal layer structure can also be a central symmetrical structure such as a square, a triangle, a trapezoid, etc.

[0079] The metal layer structure is symmetrical about the unit center, achieving high angular stability; the metal layer is attached to the dielectric layer and has a thickness of 50 microns. The first dielectric layer and the second dielectric layer have the same shape and size, and the dielectric material is PMMA.

[0080] The surface-mounted metasurface can be used compatible with 5G CPE or 6G RIS to further improve indoor signal coverage.

[0081] Example 4 The electronic device of the present invention includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or loaded from a storage unit into a random access memory (RAM). In the RAM, various programs and data required for device operation can also be stored. The CPU, ROM and RAM are connected to each other via a bus. An input / output (I / O) interface is also connected to the bus.

[0082] Multiple components in the device are connected to the I / O interface, including: input units, such as keyboards, mice, etc.; output units, such as various types of displays, speakers, etc.; storage units, such as disks, optical disks, etc.; and communication units, such as network cards, modems, wireless communication transceivers, etc. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunication networks.

[0083] The processing unit performs the various methods and processes described above. For example, in some embodiments, the method can be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program can be loaded and / or installed on the device via a ROM and / or a communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps of the method described above can be performed. Alternatively, in other embodiments, the CPU can be configured to perform the method in any other appropriate manner (e.g., by means of firmware).

[0084] The functions described above herein may be performed at least in part by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), and the like.

[0085] The program code for implementing the method of the present invention can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0086] In the context of the present invention, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0087] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A design method for a multi-frequency transparent transmission type surface mount metasurface structure, characterized in that: The method comprises the following steps: Step 1, using a cascaded transmission matrix to characterize the multilayer structure of a glass surface mounted metasurface; wherein the metasurface includes a metal layer and a dielectric layer; Step 2, using the conversion relationship between the characterized cascade transmission matrix and the scattering matrix, the corresponding transmission coefficient is calculated, and the theoretical optimal transmission coefficient of the target frequency band under the structure is obtained by adjusting the dielectric constant and thickness of the metasurface dielectric layer and the equivalent impedance of the metasurface metal layer; Step 3, determining the initial structure and parameter variation range of the metasurface unit to be optimized, and simulating to obtain the transmission coefficient under the initial structure of the metasurface; Step 4: Based on the transmission coefficient of the initial structure of the metasurface, taking the theoretical optimal transmission coefficient as the optimization target, within the given parameter variation range, the quasi-Newton algorithm is used to optimize the metasurface design to obtain the metasurface structure corresponding to the optimal transmission coefficient.

2. The design method of a multi-frequency transparent transmission type surface mount metasurface structure according to claim 1, characterized in that: When the glass is Low-E glass, the multilayer structure of the Low-E glass surface-mounted super-surface includes a Low-E glass portion and a super-surface portion, wherein the Low-E glass portion includes a first glass layer, a coating layer, a vacuum layer, and a second glass layer arranged in sequence, and the super-surface is mounted on the second glass layer; The metasurface includes metal layers and dielectric layers arranged at intervals, including: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, ... an n-1th metal layer, an n-1th dielectric layer and an nth metal layer arranged in sequence, wherein n is greater than 1; Or the metasurface includes metal layers and dielectric layers arranged at intervals, including: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer...the n-1th metal layer, the n-1th dielectric layer, the nth metal layer and the nth dielectric layer are arranged in sequence; wherein n is greater than or equal to 1.

3. The design method of a multi-frequency transparent transmission type surface mount metasurface structure according to claim 2, characterized in that: The transmission matrix of the metasurface metal layer is characterized as: in, Z ms is the equivalent impedance; Coatings in Low-E Glass It is expressed as: in, Z coating Represents the equivalent square resistance of the coating; The transmission matrix of other layers of Low-E glass surface mounted ultra-surface glass is defined as follows: in, d n For the n The thickness of the dielectric layer, For the n The wave impedance of the layer medium, η 0 is the air wave impedance, For the n The wave number of the layer medium, For the n The dielectric constant of the layer medium relative to air, For the n The magnetic permeability of the layer medium relative to air, f is the frequency of the electromagnetic wave, c is the speed of light in a vacuum; Therefore, for the surface-mounted meta-glass with L target frequency bands, when the last layer is a metal layer, the multi-layer structure is characterized by the cascade of transmission matrices: For surface-mounted meta-glass with L target frequency bands, when the last layer is a non-metallic layer, the multi-layer structure is characterized by the cascade of transmission matrices: in, T glass1 、T coating 、T vacuum 、T glass2 、T MS1 、T PMMA1 、T MS2 、T PMMA2 、 They respectively represent the transmission matrices of the first glass layer, coating layer, vacuum layer and second glass layer, first metal layer, first dielectric layer, second metal layer, second dielectric layer...nth metal layer, nth dielectric layer, where L is the number of frequency bands and L is greater than 2.

4. The design method of a multi-frequency transparent transmission type surface mount metasurface structure according to claim 1, characterized in that: Assume that the cascade transmission matrix of the surface-mounted meta-glass is The scattering matrix is , then the corresponding transmission coefficient The calculation of is as follows: in, η 0 is the wave impedance of air.

5. The design method of a multi-frequency transparent transmission type surface mount metasurface structure according to claim 1, characterized in that: The initial structure of the metasurface metal layer adopts a circular ring structure. The circular ring structure of the metal layer depends on the equivalent transmission line circuit of the glass surface-mounted metasurface. If the equivalent transmission line circuit of a metal layer transmission matrix is ​​a parallel structure, the corresponding initial structure is a double circular ring structure; if the equivalent transmission line circuit of a metal layer transmission matrix is ​​a series structure, the corresponding initial structure is a single circular ring structure.

6. The design method of a multi-frequency transparent transmission type surface mount metasurface structure according to claim 1, characterized in that: The structure of the supersurface metal layer is symmetrical about the center of the supersurface unit.

7. The design method of a multi-frequency transparent transmission type surface mount metasurface structure according to claim 1, characterized in that: The circular ring of the metasurface metal layer is equally divided into eight short microstrip lines, and independent parameters are used to define their positions and lengths and widths. The corresponding optimization space is the position, length and width of each metal layer circular ring on the short microstrip line and the thickness of each dielectric layer.

8. The design method of a multi-frequency transparent transmission type surface mount metasurface structure according to claim 1, characterized in that: The metasurface structure corresponding to the optimal transmission coefficient obtained in step 4 includes: Based on the transmission performance of the initial structure, the theoretical optimal transmission coefficient is used as the optimization target, a convergence threshold is set, and an initial parameter is determined. As a starting point for the algorithm to start optimizing and select a matrix ,by Optimize for direction; Based on current point With the previous point The gradient information of to update the matrix , determine the next optimization direction, update The expression is: in, k To optimize the number of times, ; is the transmission coefficient exist x = The first derivative of ; is the transmission coefficient exist x = The first derivative of ; If the difference between the transmission coefficient of the current point and the set optimization target is greater than the preset threshold, the termination condition is not met, and the next round of optimization will continue; if the termination condition is met, it is considered that the algorithm has converged to the optimal solution, the optimization is stopped, and the hypersurface structure of the optimal point is output.

9. The design method of a multi-frequency transparent transmission type surface mount metasurface structure according to claim 1, characterized in that: The dielectric material of the dielectric layer is PMMA.

10. An electronic device comprising a memory and a processor, wherein a computer program is stored in the memory, wherein: When the processor executes the program, the method according to any one of claims 1 to 9 is implemented.

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