Design method of reflective linear-to-circular polarization conversion metasurface and related equipment

Abstract

The application discloses a design method of a reflective linear-to-circular polarization conversion metasurface, comprising the following steps: constructing a frame structure of the reflective linear-to-circular polarization conversion metasurface; establishing two corresponding equivalent circuit models under two mutually orthogonal incident electric field modes according to the frame structure of the reflective linear-to-circular polarization conversion metasurface; obtaining the impedance of a metal dipole layer according to the surface current distribution of the metal dipole layer; obtaining two reflection coefficients under the two mutually orthogonal incident electric field modes according to the two equivalent circuit models and the impedance of the metal dipole layer; obtaining a linear-to-circular polarization conversion coefficient according to the two reflection coefficients; obtaining an analytical model according to the linear-to-circular polarization conversion coefficient and geometric parameters in the frame structure of the reflective linear-to-circular polarization conversion metasurface; and calculating the value of the geometric parameters of the reflective linear-to-circular polarization conversion metasurface by using the analytical model according to a required polarization conversion frequency band and a target conversion coefficient.

Description

Technical Field

[0001] This invention relates to the field of metasurface design technology, specifically to a design method and related equipment for a reflective linear-circular polarization conversion metasurface. Background Technology

[0002] Metasurfaces can be understood as planar metamaterial structures, which are artificially constructed two-dimensional structures with periodic distributions. Unlike traditional optical elements, metasurfaces control electromagnetic waves by relying on phase abrupt changes generated at the incident wave interface by the resonant unit structure, thereby changing the direction of electromagnetic wave propagation, adjusting the beam shape, changing the polarization mode, and so on, to achieve artificial control of electromagnetic waves.

[0003] The study of beam polarization characteristics has always been a hot topic, and this characteristic has spurred numerous practical applications. In controlling the polarization state of waves, metasurface-based linear-circular polarization converters offer advantages such as simple structure, lightweight design, and high flexibility. In recent years, researchers have designed linear-circular polarization conversion metasurfaces with various properties, leading to the development of many design methods. Nevertheless, software full-wave simulation remains the primary design tool. Clearly, over-reliance on software simulation not only obscures the physical mechanisms but also increases time costs due to the multiple design parameters. Summary of the Invention

[0004] The purpose of this invention is to provide a design method and related equipment for a reflective linear-circular polarization conversion metasurface, so as to overcome the problems in the prior art that over-reliance on software simulation not only leads to ambiguity of the physical mechanism, but also increases the time cost due to multiple design parameters.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A design method for a reflective linear-circular polarization conversion metasurface includes:

[0007] A framework structure for a reflective linear-circular polarization conversion metasurface is constructed. Based on the framework structure of the reflective linear-circular polarization conversion metasurface, two corresponding equivalent circuit models are established under two mutually orthogonal incident electric field modes.

[0008] Obtain the surface current distribution of the metal dipole layer in the frame structure, and obtain the impedance of the metal dipole layer based on the surface current distribution of the metal dipole layer in the frame structure.

[0009] Based on two equivalent circuit models and the impedance of the metallic dipole layer, two reflection coefficients are obtained under two mutually orthogonal incident electric field modes.

[0010] The linear-circular polarization conversion coefficients are obtained based on the two reflection coefficients. Then, an analytical model is constructed based on the linear-circular polarization conversion coefficients and the geometric parameters in the reflective linear-circular polarization conversion metasurface framework structure.

[0011] Based on the required polarization conversion frequency band and the target conversion coefficient, the values ​​of the geometric parameters of the reflection-mode linear-circular polarization conversion metasurface are calculated using an analytical model.

[0012] Preferably, the framework structure of the reflective linear-circular polarization conversion metasurface includes a single or multiple layers of metal dipoles, a dielectric layer, and a metal substrate layer.

[0013] Preferably, the metal dipole layer structure is a rectangular metal strip, the metal dipole layer extends periodically in any direction on the plane of the reflection profile-circular polarization conversion metasurface, the dielectric layer is a naturally occurring medium or an artificially synthesized medium, and the metal base plate layer is a metal material plate that is approximately a perfect electrical conductor.

[0014] Preferably, the two equivalent circuit models are established based on the principle of equivalent circuits.

[0015] Preferably, the impedance of the metal dipole layer is calculated using the variational method.

[0016] Preferably, the linear-circular polarization conversion coefficient is obtained based on network transmission theory.

[0017] A design system for a reflective linear-circular polarization conversion metasurface includes:

[0018] Construction Module: Construct the framework structure of the reflective linear-circular polarization conversion metasurface, and establish two corresponding equivalent circuit models under two mutually orthogonal incident electric field modes based on the framework structure of the reflective linear-circular polarization conversion metasurface.

[0019] Impedance acquisition module: acquires the surface current distribution of the metal dipole layer in the frame structure, and obtains the impedance of the metal dipole layer based on the surface current distribution of the metal dipole layer in the frame structure.

[0020] Reflection coefficient acquisition module: Based on two equivalent circuit models and the impedance of the metal dipole layer, the two reflection coefficients under two mutually orthogonal incident electric field modes are obtained;

[0021] Analytical model acquisition module: Obtain the linear-circular polarization conversion coefficients based on the two reflection coefficients, and then obtain the analytical model based on the linear-circular polarization conversion coefficients and the geometric parameters in the reflective linear-circular polarization conversion metasurface framework structure;

[0022] Calculation module: Based on the required polarization conversion frequency band and target conversion coefficient, the values ​​of the geometric parameters of the reflection-corrugated-circular polarization conversion metasurface are calculated using an analytical model.

[0023] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements steps of a design method for a reflective linear-circular polarization conversion metasurface.

[0024] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a design method for a reflective linear-circular polarization conversion metasurface.

[0025] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a design method for a reflective linear-circular polarization conversion metasurface. First, a framework structure for the reflective linear-circular polarization conversion metasurface is constructed. The structure here is not limited to a single metasurface structure model. Any metasurface composed of similar dipole layers, dielectric layers, and metal substrate layers can be designed using the rapid design method described in the present invention. Second, the design method for the reflective linear-circular polarization conversion metasurface does not rely on any form of software simulation during implementation, which can simplify the design process of the reflective linear-circular polarization conversion metasurface and greatly shorten the time required in the design process. Attached Figure Description

[0026] Figure 1 A flowchart illustrating the design method of a reflective linear-circular polarization conversion metasurface;

[0027] Figure 2 This is a block diagram of a design system for a reflective linear-circular polarization conversion metasurface;

[0028] Figure 3 This is a flowchart illustrating a design method for a reflective linear-circular polarization conversion metasurface according to an embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of the structure of a reflective linear-circular polarization conversion metasurface unit according to an embodiment of the present invention;

[0030] Figure 5 Two equivalent circuit diagrams are provided for embodiments of the present invention to obtain a reflective linear-circular polarization conversion metasurface by irradiation with two orthogonal incident electric fields;

[0031] Figure 6 This is a schematic diagram of an array layer structure composed of reflective linear-circular polarization conversion metasurface units provided in an embodiment of the present invention;

[0032] Figure 7 The software simulation curves and analytical design curves of the conversion coefficients of the reflective linear-circular polarization conversion metasurface provided in the embodiments of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0039] The present invention will now be described in further detail with reference to the accompanying drawings:

[0040] like Figure 1 As shown, this invention provides a rapid design method for a reflective linear-circular polarization conversion metasurface, including...

[0041] S101 constructs the framework structure of a reflective linear-circular polarization conversion metasurface, and establishes two corresponding equivalent circuit models under two mutually orthogonal incident electric field modes based on the framework structure of the reflective linear-circular polarization conversion metasurface.

[0042] The framework structure of a reflective linear-circular polarization conversion metasurface includes a single or multiple layers of metal dipoles, a dielectric layer, and a metal substrate layer.

[0043] The metal dipole layer structure is a rectangular metal strip. The metal dipole layer extends periodically along any direction on the plane of the reflection profile-circular polarization conversion metasurface. The dielectric layer can be a naturally occurring medium or a special artificially synthesized medium. The metal substrate layer is a metal material plate that can be approximated as a perfect electrical conductor (PEC).

[0044] The two equivalent circuit models are established based on the principle of equivalent circuits.

[0045] S102 obtains the surface current distribution of the metal dipole layer of the frame structure, and obtains the impedance of the metal dipole layer based on the surface current distribution of the metal dipole layer of the frame structure.

[0046] The impedance of the metal dipole layer is calculated using the variational method.

[0047] S103 obtains two reflection coefficients under two mutually orthogonal incident electric field modes based on two equivalent circuit models and the impedance of the metal dipole layer.

[0048] S104 obtains the linear-circular polarization conversion coefficients based on the two reflection coefficients, and then obtains the analytical model based on the linear-circular polarization conversion coefficients and the geometric parameters in the reflective linear-circular polarization conversion metasurface framework structure;

[0049] The linear-circular polarization conversion coefficients are obtained based on network transmission theory.

[0050] The analytical model is constructed based on steps S101-S104.

[0051] S105 uses an analytical model to calculate the values ​​of the geometric parameters of the reflection-corrugated-circular polarization conversion metasurface based on the required polarization conversion frequency band and the target conversion coefficient.

[0052] One embodiment of the present invention provides a design method for a reflective linear-circular polarization conversion metasurface, such as... Figure 3 As shown, it includes the following steps:

[0053] Step 1: Determine the framework structure of the reflective linear-circular polarization conversion metasurface, and determine the structural composition of each layer of the reflective linear-circular polarization conversion metasurface unit;

[0054] Step 2: Establish equivalent circuit models. Based on the metasurface structure, establish two corresponding equivalent circuit models under two mutually orthogonal incident electric field modes.

[0055] Step 3: Based on the surface current distribution of the metal dipole layer, the impedance of the metal dipole layer in the equivalent circuit model is obtained using the variational method.

[0056] Step 4: Solve for the two reflection coefficients under two mutually orthogonal incident electric fields based on the equivalent circuit model;

[0057] Step 5: Solve for the line-circular polarization conversion coefficients using network transmission theory and analytically correlate them with the geometric parameters of the metasurface unit;

[0058] Step 6: Set the dielectric constant and thickness parameters for each dielectric layer, set the width parameter for the metal dipole unit, and set the period length parameter for the metasurface unit and the length parameter for the dipole unit as variables;

[0059] Step 7: Based on the required polarization conversion frequency band and the target polarization conversion coefficient, use the analytical model to solve for the values ​​of each variable of the reflection-line-circular polarization conversion metasurface unit.

[0060] The following example, a three-layer reflective linear-circular polarization conversion metasurface design, illustrates the specific implementation of this method:

[0061] In step 1, the determined reflective linear-circular polarization conversion metasurface unit structure consists of three parts, such as... Figure 4 As shown, the top consists of metal dipole units of length d and width t arranged along the v direction, and the middle consists of units with a relative permittivity of ε. r A dielectric layer with a thickness of h is formed, and a metal base plate is formed at the bottom.

[0062] In one embodiment, in step 2, the dielectric layer and the metal ground plane are equivalent to having a characteristic impedance of propagation wavenumber is A transmission line of length h with its end short-circuited. A metallic dipole can only produce an equivalent impedance Z under the influence of an electric field along the v direction. e In this case, two equivalent circuits can be obtained from two mutually orthogonal incident electric fields, such as... Figure 5 As shown.

[0063] In one embodiment, in step 3, for the topmost periodic metal dipole array in this embodiment, the current distribution on its unit surface is as follows:

[0064] J v =1 / t*sin[k0(d eff -|v|)],(|u|≤t / 2,|v|≤d eff / 2)

[0065] Where t and d are the width and length of the metallic dipole, respectively; d eff =d+t represents the equivalent length used due to the effect of the small width; p u and p v These are the periods in the u and v directions, respectively. For a metal dipole array placed on a dielectric interface, the effective relative permittivity ε is introduced. r,eff =(1+ε r ) / 2 and effective wavenumber This describes the electromagnetic influence of the substrate interface on the metasurface. According to the variational method, the equivalent impedance Z of the periodic metallic dipole array at the dielectric interface is... e as follows:

[0066]

[0067]

[0068] J vmn It is the induced current J v The mn-th Fourier component, Z mn It is the wave impedance of the mn-th order mode.

[0069] In one embodiment, in step 4, according to... Figure 5 The two equivalent circuit models shown can be used to solve for the two reflection coefficients under two mutually orthogonal incident fields:

[0070]

[0071]

[0072] Z v =Z e Z txline / (Z e +Z txline ),

[0073] Where R u and R v These are the reflection coefficients under perpendicular incident electric fields with U-polarization and V-polarization, respectively, Z u and Z v These are the equivalent circuit input impedances under u-polarized and v-polarized vertical incident electric field illumination, respectively.

[0074] In one embodiment, in step 5, the line-circular polarization conversion coefficient is solved using network transmission theory and then analytically correlated with the geometric parameters of the metasurface unit in steps 1-4. The network transmission theory formula is as follows:

[0075]

[0076] Among them, R RCP The conversion coefficient from x-polarized incident wave to right-hand circularly polarized reflected wave; R LCP The conversion coefficient from x-polarized incident wave to left-hand circularly polarized reflected wave; at this time, the conversion coefficient R LCP It can be linked to the analytical geometry of metasurface units.

[0077] In one embodiment, in step 6, the dielectric constant ε of the intermediate dielectric layer is set. r The thickness h is 2.56 mm, the width t of the metal dipole unit is set to 0.2 mm, and the period length p of the metasurface unit and the dipole d unit are set as variables.

[0078] In one embodiment, in step 7, the fixed linear-circular polarization conversion frequency band is 12.0 GHz-18.0 GHz and the fixed conversion coefficient is 99.9%. According to the analytical model, the geometric parameters p and d of the metasurface are 9.6 mm and 9.3 mm, respectively.

[0079] The designed reflective linear-circular polarization conversion metasurface units are periodically arranged into a metasurface array, such as... Figure 6 As shown, linear-to-circular polarization conversion performance with a conversion rate greater than 99.9% from x-polarized incident electric field to left-hand circularly polarized reflected electric field can be achieved in the 12.0GHz-18.0GHz frequency band.

[0080] The rapid design method for reflective linear-circular polarization conversion metasurfaces proposed in this invention enables analytical design of reflective linear-circular polarization conversion metasurface structures composed of arbitrary numbers of metal dipole layers, dielectric layers, and metal substrate layers. Verification shows that the reflective linear-circular polarization conversion metasurfaces designed using this method can accurately achieve the set target performance, and their linear-circular polarization conversion rate curve closely matches the curve obtained from CST full-wave simulation. Figure 7 As shown.

[0081] like Figure 2 As shown, the present invention also provides a design system for a reflective linear-circular polarization conversion metasurface, comprising:

[0082] Construction Module: Construct the framework structure of the reflective linear-circular polarization conversion metasurface, and establish two corresponding equivalent circuit models under two mutually orthogonal incident electric field modes based on the framework structure of the reflective linear-circular polarization conversion metasurface.

[0083] Impedance acquisition module: acquires the surface current distribution of the metal dipole layer in the frame structure, and obtains the impedance of the metal dipole layer based on the surface current distribution of the metal dipole layer in the frame structure.

[0084] Reflection coefficient acquisition module: Based on two equivalent circuit models and the impedance of the metal dipole layer, the two reflection coefficients under two mutually orthogonal incident electric field modes are obtained;

[0085] Analytical model acquisition module: Obtain the linear-circular polarization conversion coefficients based on the two reflection coefficients, and then construct the analytical model based on the above modules and the geometric parameters in the reflective linear-circular polarization conversion metasurface framework structure;

[0086] Calculation module: Based on the required polarization conversion frequency band and target conversion coefficient, the values ​​of the geometric parameters of the reflection-corrugated-circular polarization conversion metasurface are calculated using an analytical model.

[0087] An embodiment of the present invention provides a terminal device. This terminal device includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the various method embodiments described above. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the various device embodiments described above.

[0088] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.

[0089] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0090] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0091] The memory can be used to store the computer program and / or module. The processor implements various functions of the terminal device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0092] If the modules / units integrated into the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0093] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art, guided by the specification, can make many other modifications without departing from the scope of the claims of the present invention, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A design method for a reflective linear-circular polarization conversion metasurface, characterized in that, include: A framework structure for a reflective linear-circular polarization conversion metasurface is constructed. Based on the framework structure of the reflective linear-circular polarization conversion metasurface, two corresponding equivalent circuit models are established under two mutually orthogonal incident electric field modes. Obtain the surface current distribution of the metal dipole layer in the frame structure, and obtain the impedance of the metal dipole layer based on the surface current distribution of the metal dipole layer in the frame structure. Based on two equivalent circuit models and the impedance of the metallic dipole layer, two reflection coefficients are obtained under two mutually orthogonal incident electric field modes. The linear-circular polarization conversion coefficients are obtained based on the two reflection coefficients. Then, an analytical model is constructed based on the linear-circular polarization conversion coefficients and the geometric parameters in the reflective linear-circular polarization conversion metasurface framework structure. Based on the required polarization conversion frequency band and the target conversion coefficient, the values ​​of the geometric parameters of the reflection-mode linear-circular polarization conversion metasurface are calculated using an analytical model.

2. The design method of a reflective linear-circular polarization conversion metasurface according to claim 1, characterized in that, The framework structure of the reflective linear-circular polarization conversion metasurface includes a single or multiple layers of metal dipoles, a dielectric layer, and a metal substrate layer.

3. The design method of a reflective linear-circular polarization conversion metasurface according to claim 2, characterized in that, The metal dipole layer structure is a rectangular metal strip. The metal dipole layer extends periodically along any direction on the plane of the reflection profile-circular polarization conversion metasurface. The dielectric layer is a naturally occurring medium or an artificially synthesized medium. The metal base plate layer is approximately a metal material plate that is a perfect electrical conductor.

4. The design method of a reflective linear-circular polarization conversion metasurface according to claim 1, characterized in that, The two equivalent circuit models are established based on the principle of equivalent circuits.

5. The design method of a reflective linear-circular polarization conversion metasurface according to claim 1, characterized in that, The impedance of the metal dipole layer is calculated using the variational method.

6. The design method of a reflective linear-circular polarization conversion metasurface according to claim 1, characterized in that, The linear-circular polarization conversion coefficients are obtained based on network transmission theory.

7. A design system for a reflective linear-circular polarization conversion metasurface, characterized in that, include: Construction Module: Construct the framework structure of the reflective linear-circular polarization conversion metasurface, and establish two corresponding equivalent circuit models under two mutually orthogonal incident electric field modes based on the framework structure of the reflective linear-circular polarization conversion metasurface. Impedance acquisition module: acquires the surface current distribution of the metal dipole layer in the frame structure, and obtains the impedance of the metal dipole layer based on the surface current distribution of the metal dipole layer in the frame structure. Reflection coefficient acquisition module: Based on two equivalent circuit models and the impedance of the metal dipole layer, the two reflection coefficients under two mutually orthogonal incident electric field modes are obtained; Analytical model acquisition module: Obtain the linear-circular polarization conversion coefficients based on the two reflection coefficients, and then obtain the analytical model based on the linear-circular polarization conversion coefficients and the geometric parameters in the reflective linear-circular polarization conversion metasurface framework structure; Calculation module: Based on the required polarization conversion frequency band and target conversion coefficient, the values ​​of the geometric parameters of the reflection-corrugated-circular polarization conversion metasurface are calculated using an analytical model.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the design method for a reflective linear-circular polarization conversion metasurface as described in any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the design method for a reflective linear-circular polarization conversion metasurface as described in any one of claims 1 to 6.

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