Design method and device for a multi-frequency transparent transmissive surface-mounted metasurface structure

Abstract

The present invention relates to the field of surface-mounted metasurface structure design, and particularly to a design method and device for a multi-frequency transparent transmission type surface-mounted metasurface structure. The method includes: characterizing the multi-layer structure of the glass surface-mounted metasurface using a cascaded transmission matrix; wherein the metasurface includes a metal layer and a dielectric layer; calculating the corresponding transmission coefficient using the characterized cascaded transmission matrix, and obtaining the theoretical optimal transmission coefficient of the target frequency band under this structure by adjusting the dielectric constant, thickness of the metasurface dielectric layer, and the equivalent impedance of the metasurface metal layer. Determine the initial structure and parameter variation range of the metasurface unit to be optimized, and simulate the transmission coefficient of the initial metasurface structure; based on the transmission coefficient of the initial metasurface structure, with the theoretical optimal transmission coefficient as the optimization target, use the quasi-Newton algorithm to optimize the metasurface design and obtain the metasurface structure corresponding to the optimal transmission coefficient. Compared with the prior art, the present invention has the advantages of significantly and stably improving the transmission performance of multiple frequency bands, etc.

Description

Technical Field

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

[0002] With the rise of global low-carbon emission reduction, Low-E glass (Low-Emissivity glass) is widely used in building facades and automotive glass. Low-E glass usually consists of two glass substrates with a vacuum gap in the middle and a metal coating on the inner surface of the substrates. This structure shows excellent efficiency in terms of heat insulation and sound insulation. However, in 5G or / and 6G communication, due to the short wavelength of electromagnetic waves, the transmission loss of electromagnetic waves through window glass increases significantly. This change weakens the intensity of electromagnetic signals penetrating the window into the room, thus affecting the signal coverage of outdoor base stations to indoor areas.

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

[0004] After retrieval, Chinese Patent Application Publication No. CN117668954A discloses a design method and system for a metasurface band-pass filter resonance structure, including generating data to train a VAE (Variational Autoencoder) model using simulation software; inputting the target transmission spectrum into the VAE decoder to generate and screen candidate unit structures; using the candidate unit structures as initial values, and obtaining the optimal unit structure through a global optimization algorithm combined with a prediction network and numerical simulation. However, this method does not consider the requirements of multiple frequency bands and is difficult to meet the actual application requirements of signal transmission in multiple frequency bands in 5G / 6G communication. In addition, this design method does not limit the proportion of metal in the metasurface, resulting in the inability to effectively ensure light transmittance and is not applicable to modern glass windows that require high light transmittance.

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

[0006] How to improve the transmission ability of Low-E glass to multi-frequency electromagnetic signals becomes a technical problem to be solved. Summary of the Invention

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

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] According to one aspect of the present invention, a design method for a multi-frequency transparent transmission type surface-mounted metasurface structure is provided, and the method includes the following steps:

[0010] Step 1, characterize the multi-layer structure of the glass surface-mounted metasurface with a cascaded transmission matrix; wherein the metasurface includes a metal layer and a dielectric layer;

[0011] Step 2, use the conversion relationship between the characterized cascaded transmission matrix and the scattering matrix to calculate the corresponding transmission coefficient, and obtain the theoretical optimal transmission coefficient of the target frequency band under this structure by adjusting the dielectric constant, thickness of the dielectric layer of the metasurface and the equivalent impedance of the metal layer of the metasurface;

[0012] Step 3, determine the initial structure and parameter variation range of the metasurface unit to be optimized, and simulate the transmission coefficient of the initial structure of the metasurface;

[0013] Step 4, based on the transmission coefficient of the initial structure of the metasurface, with the theoretical optimal transmission coefficient as the optimization target, in the given parameter variation range, use the quasi-Newton algorithm to optimize the metasurface design and obtain the metasurface structure corresponding to the optimal transmission coefficient.

[0014] Preferably, when the glass is Low-E glass, the multi-layer structure of the Low-E glass surface-mounted metasurface includes a Low-E glass part and a metasurface part, wherein the Low-E glass part includes a first glass layer, a coating, a vacuum layer and a second glass layer arranged in sequence, and the metasurface is surface-mounted on the second glass layer;

[0015] The metasurface includes a metal layer and a dielectric layer arranged at intervals, including: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer... an (n - 1)th dielectric layer and an nth metal layer are arranged in sequence, where n is greater than 1;

[0016] Or the metasurface includes a metal layer and a dielectric layer arranged at intervals, including: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer... an (n - 1)th metal layer, an (n - 1)th dielectric layer, an nth metal layer and an nth dielectric layer are arranged in sequence; where n is greater than or equal to 1.

[0017] More preferably, the transmission matrix of the metasurface metal layer is characterized as:

[0018]

[0019] Where, Z ms is the equivalent impedance;

[0020] The coating in Low-E glass is expressed as:

[0021]

[0022] Where, Z coating represents the equivalent sheet resistance of the coating;

[0023] The transmission matrices of other layer structures of the Low-E glass surface-mounted metasurface glass are defined as follows:

[0024]

[0025]

[0026] Where, d n is the thickness of the n th dielectric layer, is the wave impedance of the n th dielectric layer, η 0 is the air wave impedance, is the wave number of the n th dielectric layer, is the n th dielectric layer's relative permittivity to air, is the n th dielectric layer's relative permeability to air, f is the frequency of the electromagnetic wave, c is the speed of light in vacuum;

[0027] Therefore, for the surface-mounted metasurface glass of L target frequency bands, when the last layer is a metal layer, the multi-layer structure is characterized as a cascade of transmission matrices:

[0028]

[0029] For the surface-mounted metasurface glass of L target frequency bands, when the last layer is a non-metal layer, the multi-layer structure is characterized as a cascade of transmission matrices:

[0030]

[0031] Among them, T glass1 、T coating 、T vacuum 、T glass2 、T MS1 、T PMMA1 、T MS2 、T PMMA2 、 respectively represent the transmission matrices of the first glass layer, the coating layer, the vacuum layer and the second glass layer, the first metal layer, the first dielectric layer, the second metal layer, the second dielectric layer... the nth metal layer, the nth dielectric layer, where L is the number of frequency bands and L is greater than 2.

[0032] Preferably, assuming that the cascade transmission matrix of the surface-mounted metasurface glass is , and the scattering matrix is , then the corresponding transmission coefficient is calculated as follows:

[0033]

[0034] Among them, η 0 is the air wave impedance.

[0035] Preferably, the initial structure of the metasurface metal layer adopts an annular structure, and the annular 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 the transmission matrix of a certain metal layer is a parallel structure, the corresponding initial structure is a double-ring structure; if the equivalent transmission line circuit of the transmission matrix of a certain metal layer is a series structure, the corresponding initial structure is a single-ring structure.

[0036] Preferably, the structure of the metasurface metal layer is symmetric about the center of the metasurface unit.

[0037] Preferably, the ring of the metasurface metal layer is equally divided into eight short microstrip lines, and its position, length, and width are defined using independent parameters. The corresponding optimization space is the position, length, and width of the ring of each metal layer on the short microstrip lines and the thickness of each dielectric layer.

[0038] Preferably, the metasurface structure corresponding to the optimal transmission coefficient obtained in step 4 includes:

[0039] Based on the transmission performance of the initial structure, with the theoretical optimal transmission coefficient as the optimization goal, set a convergence threshold, and determine an initial parameter as the starting point for the algorithm to start optimization and select a matrix , and optimize in the direction of ;

[0040] According to the gradient information of the current point and the previous point , update the matrix , determine the next optimization direction, and the update expression is:

[0041]

[0042] where k is the number of optimization times, ; is the transmission coefficient at x = the first-order derivative; is the transmission coefficient at x = the first-order derivative;

[0043] If the difference between the transmission coefficient of the current point and the set optimization goal is greater than the preset threshold and the termination condition is not satisfied, continue the next round of optimization; if the termination condition is satisfied, it is considered that the algorithm has converged to the optimal solution, stop the optimization, and output the metasurface structure of the optimal point.

[0044] Preferably, the dielectric material of the dielectric layer is PMMA.

[0045] According to another aspect of the present invention, an electronic device is provided, including a memory and a processor. A computer program is stored on the memory, and when the processor executes the program, the method described above is implemented.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The present invention characterizes the multi-layer structure of the glass-mounted metasurface with a cascaded transmission matrix, derives the theoretically optimal transmission performance for the target frequency band, and uses the theoretically optimal transmission performance as the optimization objective for the optimization design. After the metasurface designed on the glass-mounted surface, the transmission ability of the electromagnetic signal at multiple frequency bands is close to the theoretically optimal transmission ability compared with the glass.

[0048] (2) The metal layer of the present invention is designed with a simple circular ring structure. The circular rings of each metal layer are equally divided into eight short microstrip lines, and independent parameters are used to define their positions, lengths, and widths. The quasi-Newton algorithm is used to optimize the design of the metasurface applicable to multiple target frequency bands in the optimization space, and simultaneous optimization and adjustment are performed for different frequency bands, significantly improving the transmission performance of Low-E glass at multiple target frequency points.

[0049] (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 light transmittance and high angular stability.

[0050] (4) The mounted metasurface designed by the present invention is different from the integrated manufacturing process of window glass and has the convenience of deployment. The metasurface design can be directly mounted on the installed building window glass and can be used in compatibility with 5G CPE or 6G RIS, further improving the indoor signal coverage. Description of the Drawings

[0051] Figure 1 is a schematic flow chart of the design method of the triple-band transparent transmissive mounted metasurface based on Low-E glass in the present invention;

[0052] Figure 2 is a schematic diagram of the integrated structure model of Low-E glass and the triple-band transparent transmissive mounted metasurface in Embodiment 2 of the present invention;

[0053] Figure 3 is a schematic diagram of the equivalent transmission line circuit of the multi-layer structure of the Low-E glass-mounted triple-band metasurface in Embodiment 2 of the present invention;

[0054] Figure 4 is a schematic diagram of the optimal transmission performance curve of the Low-E glass-mounted triple-band metasurface at the target frequency point in Embodiment 2 of the present invention;

[0055] Figure 5 is a schematic diagram of the initial shape of the metasurface unit to be optimized in Embodiment 2 of the present invention;

[0056] Figure 6 is a schematic diagram of the double-circular-ring structure of the metal layer of the metasurface unit to be optimized in Embodiment 2 of the present invention;

[0057] Figure 7 is a schematic diagram of the single-circular-ring structure of the metal layer of the metasurface unit to be optimized in Embodiment 2 of the present invention;

[0058] Figure 8 It is a schematic diagram of the optimal design structure of the triple-frequency transparent transmissive surface-mounted metasurface unit in Embodiment 2 of the present invention;

[0059] Figure 9 It is a schematic diagram of the optimal first metal layer structure of the triple-frequency transparent transmissive surface-mounted metasurface unit in Embodiment 2 of the present invention;

[0060] Figure 10 It is a schematic diagram of the optimal second metal layer structure of the triple-frequency transparent transmissive surface-mounted metasurface unit in Embodiment 2 of the present invention;

[0061] Figure 11 It is a schematic diagram of the optimal third metal layer structure of the triple-frequency transparent transmissive surface-mounted metasurface unit in Embodiment 2 of the present invention;

[0062] Figure 12 It is a schematic diagram showing the penetration performance of the incident signal before and after the triple-frequency metasurface is surface-mounted on the Low-E glass in Embodiment 2 of the present invention;

[0063] Figure 13 It is a schematic diagram of the integrated structure model of the Low-E glass and the quadruple-frequency transparent transmissive surface-mounted metasurface in Embodiment 3 of the present invention;

[0064] Figure 14 It is a schematic diagram of the multi-layer structure equivalent transmission line circuit of the Low-E glass surface-mounted with the quadruple-frequency metasurface in Embodiment 3 of the present invention;

[0065] Figure 15 It is a schematic diagram of the optimal transmission performance curve of the Low-E glass surface-mounted with the quadruple-frequency metasurface at the target frequency point in Embodiment 3 of the present invention;

[0066] Figure 16 It is a schematic diagram of the initial shape of the metasurface unit to be optimized in Embodiment 3 of the present invention;

[0067] Figure 17 It is a schematic diagram of the double-ring structure of the metal layer of the metasurface unit to be optimized in Embodiment 3 of the present invention;

[0068] Figure 18 It is a schematic diagram of the single-ring structure of the metal layer of the metasurface unit to be optimized in Embodiment 3 of the present invention;

[0069] Figure 19 It is a schematic diagram of the optimal design structure of the quadruple-frequency transparent transmissive surface-mounted metasurface unit in Embodiment 3 of the present invention;

[0070] Figure 20 It is a schematic diagram of the optimal first metal layer structure of the quadruple-frequency transparent transmissive surface-mounted metasurface unit in Embodiment 3 of the present invention;

[0071] Figure 21It is a schematic diagram of the optimal second metal layer structure of the four-frequency transparent transmissive surface-mounted metasurface unit in Embodiment 3 of the present invention;

[0072] Figure 22 It is a schematic diagram of the optimal third metal layer structure of the four-frequency transparent transmissive surface-mounted metasurface unit in Embodiment 3 of the present invention;

[0073] Figure 23 It is a schematic diagram of the optimal fourth metal layer structure of the four-frequency transparent transmissive surface-mounted metasurface unit in Embodiment 3 of the present invention;

[0074] Figure 24 It is a schematic diagram showing the penetration performance of the incident signal by the four-frequency metasurface before and after being surface-mounted on Low-E glass in Embodiment 3 of the present invention;

[0075] In the drawings, 1 is the first metal layer, 2 is the first dielectric layer, 3 is the second metal layer, 4 is the second dielectric layer, 5 is the third metal layer, 6 is the third dielectric layer, and 7 is the fourth metal layer. Detailed implementation manners

[0076] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0077] Embodiment 1

[0078] This embodiment relates to a design method for a multi-frequency transparent transmissive surface-mounted metasurface structure. For 5G / 6G communication, after the metasurface designed by the present invention is surface-mounted on the glass, the electromagnetic signal transmission ability of the glass can be improved at multiple target frequency points. In addition, the designed metasurface takes into account the advantages of high light transmittance and high angular stability, and can be directly surface-mounted on the installed building window glass to improve the transmission ability of the window glass at multiple target frequency bands and enhance the indoor signal access.

[0079] As Figure 1 , this method includes the following steps:

[0080] Characterize the multi-layer structure of the glass surface-mounted metasurface according to the transfer matrix method, and use the transfer matrix to equivalent each layer structure to a section of transmission line circuit and analyze the scattering problem of the incident electromagnetic wave. Using the conversion relationship between the transfer matrix and the scattering matrix , calculate the corresponding transmission coefficient :

[0081]

[0082] By adjusting the permittivity, thickness of the dielectric layer of the metasurface, and the equivalent impedance of the metasurface metal layer, the theoretical optimal transmission coefficient of the glass-mounted metasurface structure at the target frequency band is analyzed;

[0083] Determine the initial structure and parameter variation range of the metasurface unit to be optimized, and simulate the transmission coefficient of the metasurface unit under the initial structure;

[0084] Based on the transmission coefficient of the metasurface unit under the initial structure, taking the theoretical optimal transmission coefficient obtained by the transfer matrix method As the optimization goal, within the given parameter variation range, the quasi-Newton algorithm is used to optimize the metasurface design to obtain a metasurface unit that is closest to the theoretical optimal transmission coefficient.

[0085] The transfer matrix of each layer structure of the glass-mounted metasurface is defined as:

[0086]

[0087]

[0088] Among them, d n is the thickness of the n th layer of dielectric, is the wave impedance of the n th layer of dielectric, η 0 is the air wave impedance, is the wave number of the n th layer of dielectric, is the n th layer of dielectric's relative permittivity to air, is the n th layer of dielectric's relative permeability to air, f is the frequency of the electromagnetic wave, c is the speed of light in vacuum; for the equivalent impedance of the metasurface metal layer Z ms , its transfer matrix can be characterized as:

[0089]

[0090] The multi-layer structure of the glass-mounted metasurface can be characterized as the cascade of transfer matrices:

[0091]

[0092]

[0093] By adjusting the equivalent impedance and material parameters of the metal layer of the metasurface, including the permittivity and thickness of the tunable layer structure, the theoretical optimal transmission performance of the glass-mounted metasurface in the target frequency band is analyzed and obtained.

[0094] The process of the quasi-Newton algorithm includes:

[0095] Taking the change range of the geometric shape, size, and material parameters of the metasurface unit as the optimization space, setting the optimization goal and the corresponding convergence threshold for the corresponding frequency band, and determining an initial parameter as the starting point for the algorithm to start optimization and selecting a matrix , and optimizing in the direction of ;

[0096] According to the gradient information of the current point and the previous point , update the matrix , determine the next optimization direction, and update the expression as:

[0097]

[0098] where k is the number of optimization times, ; is the transmission coefficient at x = the first derivative; is the transmission coefficient at x = the first derivative.

[0099] If the difference between the function value of the current optimization point and the set optimization goal is greater than the preset threshold and the termination condition is not satisfied, then continue to return to the optimization calculation step for the next round of optimization; if the termination condition is satisfied, it is considered that the algorithm has converged to the optimal solution, and the optimization can be stopped and the optimal design can be output.

[0100] The method in this embodiment is applicable to the design of multi-frequency transparent transmissive surface-mounted metasurfaces for any glass with a known structure, such as Low-E glass, double-layer white glass, single-layer glass, etc.

[0101] Embodiment 2

[0102] This embodiment relates to a design method for a multi-frequency transparent transmissive surface-mounted metasurface structure, and designs a three-frequency transmissive surface-mounted metasurface structure. Here, Low-E glass is taken as an example, but the design method is also applicable to other glasses with a known structure. Such as Figure 1 , the method includes the following steps:

[0103] Step 101: Use the transfer matrix to characterize asFigure 2 The multi-layer structure of the Low-E glass surface-mounted metasurface shown; where the Low-E glass part is located outdoors and the metasurface part is located indoors. The Low-E glass part includes, in sequence, a first glass layer, a coating layer, a vacuum layer, and a second glass layer. The metasurface is surface-mounted on the second glass layer. Each metasurface unit includes a metal layer and a dielectric layer, where 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.

[0104] The multi-layer structure of the Low-E glass surface-mounted triple-band metasurface can be characterized as a cascade of transmission matrices:

[0105]

[0106] where T glass1 、T coating 、T vacuum 、T glass2 、T MS1 、T PMMA1 、T MS2 、T PMMA2 、 and T MS3 respectively represent the transmission matrices of the first glass layer, the coating layer, the vacuum layer, and the 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). The equivalent transmission line circuit of the Low-E glass surface-mounted metasurface is as Figure 3 shown.

[0107] The transmission matrices of each layer structure are defined as:

[0108]

[0109]

[0110] where, d n is the thickness of the dielectric, is the wave impedance of the dielectric, η 0 is the air wave impedance, is the relative permittivity of the dielectric with respect 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 vacuum. The thicknesses of the first glass layer and the second glass layer d glass1 =d glass2 = 6 cm, and the relative permittivity of the glass relative to air is 6.98. The thickness of the vacuum layer d vacuum = 12 mm, and the relative permittivity of the vacuum relative to air is 1. The relative permittivity of the medium PMMA relative to air is 3.8, and the thicknesses of the first medium layer (PMMA1) and the second medium layer (PMMA2) are respectively d 1, d 2. The magnetic permeabilities of the glass, the vacuum, and the medium PMMA relative to air are all 1, and the air wave impedance η 0 is 377.

[0111] The coating in the Low-E glass is expressed as

[0112]

[0113] where Z coating = 4 Ω / m 2 represents the equivalent sheet resistance of the coating.

[0114] For the equivalent impedance of the metasurface metal layer Z ms , its transmission matrix can be expressed as:

[0115]

[0116] Step 102: Analyze the characterized cascaded 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 this structure.

[0117] Using the conversion relationship between the transmission matrix and the scattering matrix, calculate the transmission coefficient at this time:

[0118]

[0119] By adjusting the thicknesses of the medium layers PMMA1 and PMMA2 , and the equivalent impedance of the metasurface metal layer Z MS1 , Z MS2 , ZMS3 , analyze the theoretical optimal transmission performance of the glass-mounted metasurface at the target frequency points. As Figure 4 shown in the figure of the glass-mounted metasurface, the optimal transmission performance curves at the target frequency bands of 3.5 GHz, 4.9 GHz, and 6.2 GHz are presented. The signal intensities at 3.5 GHz, 4.9 GHz, and 6.2 GHz are improved by 10.1 dB, 10.75 dB, and 12.18 dB respectively.

[0120] Step 103: Determine the initial structure and parameter variation range of the metasurface unit to be optimized.

[0121] Establish a simple regular figure as the metal layer structure of the metasurface. Considering the requirement of light transmittance, a circular ring structure with better light transmittance is selected. The initial structure of the metasurface unit to be optimized is as Figure 5 shown. The metasurface to be optimized consists of a metal layer and a dielectric layer. The metal layer includes: the first metal layer 1, the second metal layer 3, and the third metal layer 5. The dielectric layer includes: the first dielectric layer 2 and the 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;

[0122] The initial structures of the first metal layer and the second metal layer are the same, adopting the Figure 6 double circular ring structure shown in the figure. The initial structure of the third metal layer adopts the single circular ring structure shown in Figure 7 the figure. Each circular ring of the metal layers is equally divided into eight short microstrip lines (for the double circular ring structure: 1a - 8a of the inner circular ring, 1b - 8b of the outer circular ring; for the single circular ring structure: 1a - 8a of the circular ring), and independent parameters are used to define their positions, lengths, and widths. The optimization space is the positions, lengths, and widths of the circular rings in the short microstrip lines of each layer, as well as the thicknesses of the dielectric layers PMMA1 and PMMA2 , .

[0123] Step 104: Based on the transmission performance of the initial shape, with the theoretical optimal transmission coefficient in step S102 as the optimization goal, within the optimization space determined in step S103, use the quasi-Newton algorithm to optimize the design of the triple-band metasurface.

[0124] Set the optimization goals at the target frequency points of 3.5 GHz, 4.9 GHz, and 6.2 GHz to be 10.1 dB, 10.75 dB, and 12.18 dB. At the same time, set the convergence threshold to 3 dB. With an oblique incidence of 45° as the design reference to take into account the performance of the metasurface within the oblique incidence range of 0° - 60°, use the initial parameters as the starting point for algorithm optimization, select the identity matrix , and optimize in the direction of ;

[0125] Based on the current point and the gradient information of the previous point to update the matrix and determine the next optimization direction, update The expression is:

[0126]

[0127] If the difference between the function value of the current optimization point and the set optimization target is greater than the preset threshold of 3 dB, the termination condition is not satisfied, and the optimization calculation steps are continued for the next round of optimization; if the termination condition is satisfied, 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 Figure 8 shown, where Figure 9 is the structure of the first metal layer, Figure 10 is the structure of the unit second metal layer, Figure 11 is the structure of the third metal layer.

[0128] The following further describes this embodiment according to the simulation results:

[0129] As Figure 12 , the designed triple-band transparent transmissive surface-mounted metasurface based on Low-E glass is simulated. The electromagnetic signal passes from the outside through the Low-E glass and the metasurface into the room. Compared with the Low-E glass without the surface-mounted triple-band metasurface, when the electromagnetic signal is normally incident (the incident angle is 0°), there are gains of 9.11 dB, 7.41 dB, and 8.03 dB at the target frequency points of 3.5 GHz, 4.9 GHz, and 6.2 GHz. When the electromagnetic signal is incident at 30°, there are gains of 8.25 dB, 8.60 dB, and 8.52 dB at the target frequency points of 3.5 GHz, 4.9 GHz, and 6.2 GHz. When the electromagnetic signal is incident at 60°, there are gains of 8.40 dB, 9.26 dB, and 10.26 dB at the target frequency points of 3.5 GHz, 4.9 GHz, and 6.2 GHz. The designed metasurface can stably resist electromagnetic waves incident at angles of 0° - 60° in the 3.5 GHz, 4.9 GHz, and 6.2 GHz frequency bands, and its gain relative to the Low-E glass always remains at 7.4 - 10.26 dB, and it has a transmittance of about 86.3%.

[0130] The side length of the triple-band metasurface unit is p, the metal layer structure is circular ring-shaped, the structures of the first metal layer and the second metal layer both adopt double-ring structures, and the third metal layer adopts a single-ring structure; the metal layer structure is symmetric about the unit center, achieving high-angle stability; the metal layer is attached to the dielectric layer with a thickness of 50 microns, the shapes and sizes of the first dielectric layer and the second dielectric layer are the same, the dielectric material is PMMA, and the thickness is 3 mm.

[0131] The triple - band transmissive metasurface is surface - mounted on Low - E glass and is applicable to the 5G / 6G frequency bands of N78, N79, and 6.2 GHz.

[0132] Example 3

[0133] This example relates to a design method of a multi - frequency transparent transmissive surface - mounted metasurface structure. A four - frequency transparent transmissive surface - mounted metasurface for 5G / 6G communication is designed. The steps are similar to those in Example 2:

[0134] It is beneficial to characterize the multi - layer structure of the Low - E glass surface - mounted metasurface as shown by Figure 13 The equivalent transmission line circuit of the Low - E glass surface - mounted metasurface is as shown by Figure 14 The multi - layer structure of the Low - E glass surface - mounted four - frequency metasurface can be characterized as a cascade of transmission matrices:

[0135]

[0136] Among them T glass1 、T coating 、T vacuum 、T glass2 、T MS1 、T PMMA1 、T MS2 、T PMMA2 、T MS3 、T PMMA3 、 and T MS4 respectively represent the transmission matrices of the first glass layer, the coating layer, the vacuum layer, the 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 as shown by Figure 14 shown.

[0137] Analyze the cascaded transmission matrix after characterization to obtain the optimal transmission performance at the target frequency points of 3.5 GHz, 4.9 GHz, 6.2 GHz, and 6.7 GHz for this structure: By adjusting the thicknesses of the dielectric layers PMMA1, PMMA2, and PMMA3 , and ZMS1 , Z MS2 , Z MS3 , Z MS4 , analyze the theoretical optimal transmission performance of the glass-mounted metasurface at the target frequency points. As Figure 15 shown in

[0138] Determine the initial structure and parameter variation range of the metasurface unit to be optimized: The initial structure of the metasurface unit to be optimized is as Figure 16 shown. The metasurface to be optimized consists of a metal layer and a dielectric layer. The metal layer includes: the first metal layer 1, the second metal layer 3, the third metal layer 5, and the fourth metal layer 7. The dielectric layer includes: the first dielectric layer 2, the second dielectric layer 4, and the 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.

[0139] The initial structures of the first metal layer and the fourth metal layer are the same, adopting the Figure 18 shown as a single-ring structure. The initial structures of the second metal layer and the third metal layer are the same, adopting the Figure 17 as a double-ring structure. The rings of each metal layer are equally divided into eight short microstrip lines (for the double-ring structure: 1a - 8a of the inner ring, 1b - 8b of the outer ring; for the single-ring structure: 1a - 8a of the ring), and independent parameters are used to define their positions, lengths, and widths. The optimization space is the positions, lengths, and widths of the rings in the short microstrip lines of each layer, as well as the thicknesses of the dielectric layers PMMA1, PMMA2, and PMMA3 , , .

[0140] Based on the transmission performance of the initial shape, with the theoretical optimal transmission coefficient as the optimization goal, within the optimization space, use the quasi-Newton algorithm to optimize the design of the four-frequency metasurface.

[0141] Set the optimization goals for the target frequency points 3.5 GHz, 4.9 GHz, 6.2 GHz, and 6.7 GHz to 10.23 dB, 10.30 dB, 9.03 dB, and 10.11 dB respectively, and set the convergence threshold to 3 dB. Take the oblique incidence of 45° as the design reference to balance the performance of the metasurface within the incident angle range of 0° - 60°. The initial parameters As the starting point for algorithm optimization, select the identity matrix , and perform optimization in the direction of ;

[0142] Based on the gradient information of the current point and the previous point , update the matrix to determine the next optimization direction;

[0143] If the difference between the function value of the current optimization point and the set optimization target is greater than the preset threshold of 3 dB, the termination condition is not met, and the optimization calculation steps are continued for 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 can be output. The optimal design is as shown in Figure 19 ~ Figure 23 , where Figure 20 is the structure of the first metal layer, Figure 21 is the structure of the second metal layer, Figure 22 is the structure of the third metal layer, Figure 23 is the structure of the fourth metal layer.

[0144] The following is a further description of this embodiment based on the simulation results:

[0145] Referring to Figure 24 , the designed four-frequency transmissive transparent surface-mounted metasurface based on Low-E glass is simulated. The electromagnetic signal passes from the outside through the Low-E glass and the metasurface into the room. Compared with the case of the Low-E glass without the surface-mounted four-frequency metasurface, when the electromagnetic signal is normally incident, there are gains of 7.40 dB, 6.81 dB, 7.38 dB, and 8.50 dB at the target frequencies of 3.5 GHz, 4.9 GHz, 6.2 GHz, and 6.7 GHz. When the electromagnetic signal is incident at 30°, there are gains of 8.96 dB, 7.84 dB, 7.33 dB, and 9.86 dB at the target frequencies of 3.5 GHz, 4.9 GHz, 6.2 GHz, and 6.7 GHz. When the electromagnetic signal is incident at 60°, there are gains of 10.01 dB, 7.69 dB, 8.74 dB, and 8.53 dB at the target frequencies of 3.5 GHz, 4.9 GHz, 6.2 GHz, and 6.7 GHz, as shown in Figure 13 . The designed metasurface can stably resist electromagnetic waves incident at angles of 0° - 60° in the frequency bands of 3.5 GHz, 4.9 GHz, 6.2 GHz, and 6.7 GHz. Its gain relative to the Low-E glass always remains at 6.8 - 10.01 dB, and it has a transmittance of approximately 82.5%.

[0146] The side length of the four - frequency metasurface unit is p, and the metal layer structure is an annular structure. The shapes of the first metal layer, the second metal layer, and the third metal layer all adopt a double - ring structure, and the fourth metal layer adopts a single - ring structure; the metal layer structure is symmetric about the unit center, achieving high - angle stability; the metal layer is attached to the dielectric layer with a thickness of 50 microns. The shapes and sizes of the first dielectric layer and the second dielectric layer are the same, the dielectric material is PMMA with a thickness of 0.8 mm, and the dielectric material of the third dielectric layer is PMMA with a thickness of 3 mm.

[0147] The four - frequency transmissive metasurface is surface - mounted on Low - E glass and is applicable to the 5G / 6G frequency bands of N78, N79, 6.2 GHz, and 6.7 GHz.

[0148] The high - angle stability of the multi - frequency metasurface means that when electromagnetic waves are incident at an incident angle of 0 - 60°, the transmissive multi - frequency metasurface can improve the transmission ability of the glass to electromagnetic waves, and the multi - frequency metasurface has a high light transmittance of more than 80%.

[0149] This embodiment also relates to a design method of a multi - frequency transparent transmissive surface - mounted metasurface structure, which designs a transparent transmissive surface - mounted metasurface for L target frequency bands of 5G / 6G communication, where L>2. The metasurface to be optimized consists of a metal layer and a dielectric layer. The metal layer includes: the first metal layer, the second metal layer... the nth metal layer, and the dielectric layer includes: the first dielectric layer, the second dielectric layer, and the (n - 1)th dielectric layer; the first metal layer, the first dielectric layer, the second metal layer, the second dielectric layer... the (n - 1)th metal layer, the (n - 1)th dielectric layer, and the nth metal layer are arranged in sequence, and n is greater than 1.

[0150] In addition, the metasurface to be optimized consists of a metal layer and a dielectric layer, and its structure can also be: the metal layer includes: the first metal layer, the second metal layer... the nth metal layer, and the dielectric layer includes: the first dielectric layer, the second dielectric layer, and the nth dielectric layer; the first metal layer, the first dielectric layer, the second metal layer, the second dielectric layer... the (n - 1)th metal layer, the (n - 1)th dielectric layer, the nth metal layer, and the nth dielectric layer are arranged in sequence, and n is greater than or equal to 1.

[0151] The metal layer structure is an annular structure, and the annular structure of the metal layer depends on the equivalent transmission line circuit of the glass surface - mounted metasurface, such as Figure 3 and Figure 14 , if the transmission matrix of the ith metal layer T MSi has a parallel equivalent transmission line circuit, the corresponding initial structure is a double - ring structure. If the transmission matrix of the ith metal layer in the figure T MSi has a series equivalent transmission line circuit, the corresponding initial structure is a single - ring structure. In addition to circular, the metal layer structure can also be a square, a triangle, a trapezoid and other centrosymmetric structures.

[0152] The metal layer structure is centrosymmetric about the unit center, achieving high-angle stability; the metal layer is attached to the dielectric layer with 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.

[0153] The surface-mounted metasurface can be used in compatibility with 5G CPE or 6G RIS to further improve the coverage of indoor signals.

[0154] Example 4

[0155] The electronic device of the present invention includes a central processing unit (CPU), which can execute various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or computer program instructions 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.

[0156] Multiple components in the device are connected to the I / O interface, including: an input unit, such as a keyboard, a mouse, etc.; an output unit, such as various types of displays, speakers, etc.; a storage unit, such as a disk, an optical disc, etc.; and a communication unit, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit allows the device to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0157] The processing unit executes the various methods and processes described above. For example, in some embodiments, the method can be implemented as a computer software program that 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 onto the device via the ROM and / or the communication unit. When the computer program is loaded into the RAM and executed by the CPU, one or more steps of the methods described above can be executed. Alternatively, in other embodiments, the CPU can be configured to execute the method by any other suitable means (e.g., by means of firmware).

[0158] The functions described above herein can be performed at least in part by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that can be used include: field programmable gate arrays (FPGA), application specific integrated circuits (ASIC), application specific standard products (ASSP), system on a chip (SOC), complex programmable logic devices (CPLD), and so on.

[0159] 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 a controller of a general-purpose computer, a special-purpose computer, or other programmable data processing devices, such that when the program codes are executed by the processor or the controller, the functions / operations specified in the flowchart and / or block diagram are implemented. The program codes can be executed entirely on the machine, partially on the machine, executed partially on the machine as an independent software package and partially on a remote machine, or executed entirely on a remote machine or server.

[0160] In the context of the present invention, a machine-readable medium can be a tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, 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.

[0161] As described above, only the specific embodiments of the present invention are provided, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily conceive of various equivalent modifications or substitutions, and all such modifications or substitutions should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A design method for a multi-frequency transparent transmissive surface-mounted metasurface structure, characterized in that, The method includes the following steps: Step 1, characterizing the multi-layer structure of the glass-mounted metasurface with a cascaded transmission matrix; wherein the metasurface includes a metal layer and a dielectric layer; Step 2, using the conversion relationship between the characterized cascaded transmission matrix and the scattering matrix to calculate the corresponding transmission coefficient, and obtaining the theoretical optimal transmission coefficient of the target frequency band under this structure by adjusting the permittivity, thickness of the dielectric layer of the metasurface and the equivalent impedance of the metal layer of the metasurface; Step 3, determining the initial structure and the parameter variation range of the metasurface unit to be optimized, and simulating to obtain the transmission coefficient of 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, and within the given parameter variation range, using the quasi-Newton algorithm to optimize the metasurface design to obtain the metasurface structure corresponding to the optimal transmission coefficient; The metasurface structure corresponding to the optimal transmission coefficient obtained in Step 4 includes: Based on the transmission performance of the initial structure, with the theoretical optimal transmission coefficient as the optimization goal, set a convergence threshold to determine an initial parameter as the starting point for the algorithm to start optimization and select a matrix , and optimize in the direction of ; Based on the current point and the gradient information of the previous point to update the matrix and determine the next optimization direction, the update expression is as follows: ， Among them, k is the number of optimization times, ; is the transmission coefficient at x = the first derivative; is the transmission coefficient at x = the first derivative; If the difference between the transmission coefficient of the current point and the set optimization target is greater than the preset threshold and the termination condition is not satisfied, then continue the next round of optimization; if the termination condition is satisfied, it is considered that the algorithm has converged to the optimal solution, stop the optimization, and output the metasurface structure of the optimal point.

2. The design method of a multi-frequency transparent transmissive surface-mounted metasurface structure according to claim 1, wherein When the glass is Low-E glass, the multi-layer structure of the Low-E glass-mounted metasurface includes a Low-E glass part and a metasurface part, wherein the Low-E glass part includes a first glass layer, a coating layer, a vacuum layer and a second glass layer arranged in sequence, and the metasurface is mounted on the second glass layer; The metasurface includes a metal layer and a dielectric layer arranged at intervals, including: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer... a (n-1)th metal layer, a (n-1)th dielectric layer and an nth metal layer are arranged in sequence, where n is greater than 1; Or the metasurface includes a metal layer and a dielectric layer arranged at intervals, including: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer... a (n-1)th metal layer, a (n-1)th dielectric layer, an nth metal layer and an nth dielectric layer are arranged in sequence; where n is greater than or equal to 1.

3. A design method for a multi-frequency transparent transmissive surface-mounted metasurface structure according to claim 2, characterized in that The transmission matrix of the metasurface metal layer is characterized as: ， Among them, Z ms is the equivalent impedance; Coatings in Low-E glass Expressed as: ， Among them, Z coating represents the equivalent sheet resistance of the coating; The transmission matrix of other layers of the Low-E glass-mounted metasurface glass is defined as follows: ， ， Among them, d n is the thickness of the n nth layer of the medium, is the wave impedance of the n nth layer of the medium, η 0 is the wave impedance of air, is the wave number of the n nth layer of the medium, is the relative permittivity of the n nth layer of the medium with respect to air, is the relative permeability of the n nth layer of the medium with respect to air, f is the frequency of the electromagnetic wave, c is the speed of light in vacuum; Therefore, for the glass-mounted metasurface glass of L target frequency bands, when the last layer is a metal layer, the multi-layer structure is characterized as a cascade of transmission matrices: ， For the glass-mounted metasurface glass of L target frequency bands, when the last layer is a non-metal layer, the multi-layer structure is characterized as a cascade of transmission matrices: ， Among them, T glass1 、T coating 、T vacuum 、T glass2 、T MS1 、T PMMA1 、T MS2 、T PMMA2 、 respectively represent the transfer matrices of the first glass layer, the coating layer, the vacuum layer and the second glass layer, the first metal layer, the first dielectric layer, the second metal layer, the second dielectric layer... the nth metal layer, the nth dielectric layer, where L is the number of frequency bands, L is greater than 2.

4. A design method for a multi-frequency transparent transmissive surface-mounted metasurface structure according to claim 1, characterized in that, Assume the cascaded transmission matrix of the surface-mounted metasurface glass , and the scattering matrix is . Then the calculation of the corresponding transmission coefficient is as follows: ， Among them, η 0 is the air wave impedance.

5. A design method for a multi-frequency transparent transmissive surface-mounted metasurface structure according to claim 1, characterized in that The initial structure of the metasurface metal layer adopts an annular structure, and the annular structure of the metal layer depends on the equivalent transmission line circuit of the glass-mounted metasurface. If the equivalent transmission line circuit of the transmission matrix of a certain metal layer is a parallel structure, the corresponding initial structure is a double-ring structure; if the equivalent transmission line circuit of the transmission matrix of a certain metal layer is a series structure, the corresponding initial structure is a single-ring structure.

6. The design method of a multi-frequency transparent transmissive surface-mounted metasurface structure according to claim 1, characterized in that, The structure of the metasurface metal layer is centrosymmetric about the center of the metasurface unit.

7. A design method for a multi-frequency transparent transmissive surface-mounted metasurface structure according to claim 1, characterized in that, The ring of the metasurface metal layer is equally divided into eight short microstrip lines, and its position, length, and width are defined using independent parameters. The corresponding optimization space is the position, length, and width of the ring of each metal layer on the short microstrip lines and the thickness of each dielectric layer.

8. A design method for a multi-frequency transparent transmissive surface-mounted metasurface structure according to claim 1, characterized in that, The dielectric material of the dielectric layer is PMMA.

9. An electronic device, comprising a memory and a processor, wherein a computer program is stored on the memory, characterized in that, When the processor executes the program, it implements the method according to any one of claims 1 to 8.

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