Layout method, device and equipment of frequency selection unit

Abstract

The application discloses a layout method, device and equipment of a frequency selection unit, relates to the technical field of communication, and can combine a measuring point distance field to perform projection coordinate calculation on the frequency selection unit, so that the frequency selection unit is as evenly distributed on a curved surface as possible. The method comprises the following steps: obtaining a geodesic distance field of a target curved surface calculated along a heat conduction direction, the geodesic distance field being a distance field formed by the shortest path length between two nodes on the target curved surface; performing projection coordinate calculation on the geodesic distance field on an isocline of the geodesic distance field to obtain projection coordinates of the frequency selection unit, the isocline being a line formed by connecting equal points in the geodesic distance field that meet a distance condition, the distance condition being that the geodesic distance in the geodesic distance field is the same as a reference distance, and the reference distance being a periodic arrangement distance of the frequency selection unit; and projecting the frequency selection unit to the target curved surface point by point according to the projection coordinates of the frequency selection unit to obtain a frequency selection surface on which the frequency selection unit is arranged quasi-periodically.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a method, apparatus and device for arranging frequency selection units. Background Technology

[0002] Frequency selective surfaces are composed of periodically arranged metal patch units or periodically arranged aperture units on a metal screen. They can effectively control the characteristics of electromagnetic wave phase, polarization, and propagation mode at the subwavelength level, and are the key to achieving high-performance electromagnetic protection and stealth for airborne / missile-borne radar antennas.

[0003] In related technologies, the frequency selective surface of traditional planar configuration can achieve a periodic layout by offsetting the planar structure of the frequency selective unit. However, the electromagnetic performance of the frequency selective surface is related to the periodic distance of the frequency selective unit in addition to the shape of the frequency selective unit structure. For complex curved surfaces with non-developable characteristics, it is not possible to obtain the layout of the frequency selective unit by coordinate translation. This makes it difficult to achieve a quasi-periodic layout of the frequency selective unit on non-developable complex curved surfaces. Summary of the Invention

[0004] In view of this, this application provides a method, apparatus and device for the layout of frequency-selective cells, the main purpose of which is to solve the problem that the prior art cannot obtain the layout of frequency-selective cells by coordinate translation for complex curved surfaces with non-developable characteristics, and it is difficult to achieve quasi-periodic layout of frequency-selective cells on non-developable complex curved surfaces.

[0005] According to a first aspect of this application, a method for laying out frequency-selective cells is provided, comprising:

[0006] Obtain the geodesic distance field of the target surface calculated along the heat conduction direction. The geodesic distance field is the distance field formed by the shortest path length between two nodes on the target surface.

[0007] The projection coordinates of the frequency selection unit are obtained by calculating the projection coordinates of the geodetic distance field on the contour lines of the geodetic distance field. The contour lines are lines formed by connecting the contour points in the geodetic distance field that meet the distance conditions. The distance conditions are that the geodetic distance in the geodetic distance field is the same as the preset reference distance. The reference distance is the periodic arrangement distance of the frequency selection unit.

[0008] Based on the projection coordinates of the frequency selection unit, the frequency selection unit is projected point by point onto the target surface to obtain a frequency selection surface with quasi-periodic arrangement of the frequency selection units.

[0009] Further, obtaining the geodesic distance field of the target surface calculated along the heat conduction direction includes:

[0010] The target surface is converted into a discrete surface approximated by a triangular mesh, so as to describe the geometric features of the corresponding three-dimensional structure of the target surface through the triangular mesh;

[0011] Based on the temperature field of the discrete surface, the heat conduction direction of the discrete surface is calculated. The temperature field of the discrete surface is obtained by discretizing and calculating the heat conduction equation through the grid nodes on the discrete surface. The heat conduction equation describes the rate of change of temperature with respect to time on the discrete surface.

[0012] Calculate the geodesic distance field of the target surface along the heat conduction direction of the discrete surface.

[0013] Further, calculating the heat conduction direction of the discrete surface based on its temperature field includes:

[0014] Calculate the normalized gradient field of the discrete surface based on the temperature field of the discrete surface;

[0015] In the normalized gradient field of the discrete surface, the opposite direction of the temperature gradient is selected as the heat conduction direction of the discrete surface.

[0016] Furthermore, after calculating the normalized gradient field of the discrete surface based on the temperature field of the discrete surface, the method further includes:

[0017] The normalized gradient field of the discrete surface is checked;

[0018] If the fluctuation of the normalized gradient field of the discrete surface increases in the region far from the heat source, the boundary conditions and initial conditions far from the heat source are readjusted until a stable normalized gradient field is obtained.

[0019] Accordingly, selecting the opposite direction of the temperature gradient in the normalized gradient field of the discrete surface as the heat conduction direction of the discrete surface includes:

[0020] In the stable normalized gradient field, the opposite direction of the temperature gradient is selected as the heat conduction direction of the discrete surface.

[0021] Further, the step of calculating the projected coordinates of the frequency-selective unit based on the projected coordinates of the geodesic range field on the contour lines of the geodesic range field includes:

[0022] Based on the geodesic distance field of the target surface, the contour lines of the geodesic distance field are determined according to a pre-set reference distance;

[0023] Traverse the contour lines of the geodetic distance field, and calculate the projected coordinates of the frequency-selective unit by performing projection coordinate calculations on the contour lines according to a pre-set reference distance.

[0024] Furthermore, during the process of traversing the contour lines of the geodetic distance field, if the contour lines are closed-loop contour lines, the step of calculating the projected coordinates of the frequency-selective unit by means of a pre-set reference distance on the contour lines includes:

[0025] When the ratio of the total arc length corresponding to the contour line to the reference distance is an integer multiple, the distribution of the frequency selection unit on the closed-loop contour line is determined according to the reference distance, and the projected coordinates of the frequency selection unit are obtained.

[0026] When the ratio of the total arc length corresponding to the contour line to the reference distance is not an integer multiple, the reference distance is corrected, and the distribution of the frequency selection unit on the closed-loop contour line is determined according to the corrected reference distance to obtain the projected coordinates of the frequency selection unit.

[0027] During the process of traversing the contour lines of the geodetic distance field, if the contour lines are open-loop contour lines, then the calculation of projection coordinates on the contour lines according to a pre-set reference distance to obtain the projection coordinates of the frequency-selective unit includes:

[0028] The search is performed starting from one endpoint of the open-loop contour line in the geodetic distance field. The distribution of frequency-selective units on the open-loop contour line is determined one by one according to the reference distance, and the projected coordinates of the frequency-selective units are obtained.

[0029] Further, the step of projecting the frequency selection unit point by point onto the target surface according to the projection coordinates of the frequency selection unit to obtain a frequency selection surface with quasi-periodic arrangement of the frequency selection units includes:

[0030] A local projection coordinate system is established based on the projection coordinates of the frequency selection unit to determine the projection posture of the frequency selection unit on the target surface;

[0031] Based on the local projection coordinate system, the frequency selection unit is locally offset and then projected point by point onto the target surface to obtain a frequency selection surface with quasi-periodic arrangement of frequency selection units.

[0032] According to a second aspect of this application, a layout arrangement for a frequency selection unit is provided, comprising:

[0033] The acquisition unit is used to acquire the geodesic distance field of the target surface calculated along the heat conduction direction, wherein the geodesic distance field is the distance field formed by the shortest path length between two nodes on the target surface;

[0034] The calculation unit is used to calculate the projected coordinates of the frequency selection unit based on the geodetic distance field on the contour lines of the geodetic distance field. The contour lines are lines formed by connecting the contour points in the geodetic distance field that meet the distance conditions. The distance conditions are that the geodetic distance in the geodetic distance field is the same as the preset reference distance. The reference distance is the periodic arrangement distance of the frequency selection unit.

[0035] The projection unit is used to project the frequency selection unit point by point onto the target curved surface according to the projection coordinates of the frequency selection unit, so as to obtain a frequency selection surface with quasi-periodic arrangement of the frequency selection units.

[0036] Furthermore, the acquisition unit includes:

[0037] The conversion module is used to convert the target surface into a discrete surface approximated by a triangular mesh, so as to describe the geometric features of the corresponding three-dimensional structure of the target surface through the triangular mesh;

[0038] The first calculation module is used to calculate the heat conduction direction of the discrete surface based on the temperature field of the discrete surface. The temperature field of the discrete surface is obtained by discretely calculating the heat conduction equation through the grid nodes on the discrete surface. The heat conduction equation describes the rate of change of temperature with respect to time on the discrete surface.

[0039] The second calculation module is used to calculate the geodesic distance field of the target surface along the heat conduction direction of the discrete surface.

[0040] Furthermore, the first computing module includes:

[0041] The calculation submodule is used to calculate the normalized gradient field of the discrete surface based on the temperature field of the discrete surface;

[0042] The selection submodule is used to select the opposite direction of the temperature gradient in the normalized gradient field of the discrete surface as the heat conduction direction of the discrete surface.

[0043] Furthermore, the computing submodule is specifically used for:

[0044] After calculating the normalized gradient field of the discrete surface based on the temperature field of the discrete surface, the normalized gradient field of the discrete surface is checked.

[0045] If the fluctuation of the normalized gradient field of the discrete surface increases in the region far from the heat source, the boundary conditions and initial conditions far from the heat source are readjusted until a stable normalized gradient field is obtained.

[0046] Accordingly, the selection submodule is specifically used for:

[0047] In the stable normalized gradient field, the opposite direction of the temperature gradient is selected as the heat conduction direction of the discrete surface.

[0048] Furthermore, the computing unit includes:

[0049] The determination module is used to determine the contour lines of the geodesic distance field based on the geodesic distance field of the target surface and according to a pre-set reference distance.

[0050] The third calculation module is used to traverse the contour lines of the geodetic distance field, calculate the projection coordinates on the contour lines according to the preset reference distance, and obtain the projection coordinates of the frequency selection unit.

[0051] Furthermore, during the process of traversing the contour lines of the geodesic distance field, if the contour lines are closed-loop contour lines, then the third calculation module is specifically used for:

[0052] When the ratio of the total arc length corresponding to the contour line to the reference distance is an integer multiple, the distribution of the frequency selection unit on the closed-loop contour line is determined according to the reference distance, and the projected coordinates of the frequency selection unit are obtained.

[0053] When the ratio of the total arc length corresponding to the contour line to the reference distance is not an integer multiple, the reference distance is corrected, and the distribution of the frequency selection unit on the closed-loop contour line is determined according to the corrected reference distance to obtain the projected coordinates of the frequency selection unit.

[0054] During the process of traversing the contour lines of the geodesic distance field, if the contour lines are open-loop contour lines, then the third calculation module is specifically used for:

[0055] The search is performed starting from one endpoint of the open-loop contour line in the geodetic distance field. The distribution of frequency-selective units on the open-loop contour line is determined one by one according to the reference distance, and the projected coordinates of the frequency-selective units are obtained.

[0056] Furthermore, the projection unit is specifically used for:

[0057] A local projection coordinate system is established based on the projection coordinates of the frequency selection unit to determine the projection posture of the frequency selection unit on the target surface;

[0058] Based on the local projection coordinate system, the frequency selection unit is locally offset and then projected point by point onto the target surface to obtain a frequency selection surface with quasi-periodic arrangement of frequency selection units.

[0059] According to a third aspect of this application, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described in the first aspect above.

[0060] According to a fourth aspect of this application, a readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect above.

[0061] By means of the above technical solution, the frequency selection unit layout method, apparatus and equipment provided in this application, compared with the current prior art of realizing the periodic layout of frequency selection units by planar offset of the frequency selection unit structure, this application obtains the geodesic distance field of the target surface calculated along the heat conduction direction. The geodesic distance field is the distance field formed by the shortest path length between two nodes on the target surface. The projection coordinates of the frequency selection unit are obtained by calculating the projection coordinates on the contour lines of the geodesic distance field. The contour lines are the lines formed by connecting the contour points in the geodesic distance field that meet the distance conditions. The distance condition is that the geodesic distance in the geodesic distance field is the same as the preset reference distance. The reference distance is the periodic arrangement distance of the frequency selection unit. The frequency selection unit is projected point by point onto the target surface according to the projection coordinates of the frequency selection unit to obtain the frequency selection surface of the quasi-periodic arrangement of the frequency selection unit. The entire process calculates the geodesic distance field of the target surface along the heat conduction direction, which enables the rapid calculation of the geodesic distance corresponding to the heat source, meets the arrangement requirements of the frequency-selective unit on the surface, and calculates the projected coordinates of the frequency-selective unit by combining the distance field of the measuring point, so that the frequency-selective unit is distributed as evenly as possible on the surface, thereby realizing the quasi-periodic layout of the frequency-selective unit on the complex surface.

[0062] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0063] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0064] Figure 1 This is a flowchart illustrating the layout method of the frequency selection unit in one embodiment of this application;

[0065] Figure 2 yes Figure 1 A flowchart illustrating a specific implementation method of step 101;

[0066] Figure 3 This is a discrete surface plot of a triangular mesh obtained by discretizing the target surface in one embodiment of this application;

[0067] Figure 4This is a flowchart illustrating the calculation process of the geodesic distance field of the target surface in one embodiment of this application;

[0068] Figure 5 yes Figure 1 A flowchart illustrating a specific implementation method for step 102;

[0069] Figure 6 These are the open-loop contour lines and closed-loop contour lines formed around the heat source on a discrete surface in one embodiment of this application;

[0070] Figure 7a This is a schematic diagram showing the distribution of projection points of frequency-selective units on the closed-loop contour line in one embodiment of this application;

[0071] Figure 7b This is a schematic diagram showing the distribution of projection points of frequency-selective units on an open-loop contour line in one embodiment of this application;

[0072] Figure 8 This is a flowchart illustrating the process of calculating projected coordinates based on contour lines of a geodesic distance field in one embodiment of this application.

[0073] Figure 9 yes Figure 1 A schematic diagram of a specific implementation method for step 103;

[0074] Figure 10 This is a schematic diagram showing the positional relationship of the projected coordinates of the frequency selection unit in the local projected coordinate system in one embodiment of this application;

[0075] Figure 11 This is a schematic diagram of the projection process of the frequency selection unit after position offset in one embodiment of this application;

[0076] Figure 12 This is a schematic diagram illustrating the selection of the positions of the triangular mesh and the heat source vertices in one embodiment of this application;

[0077] Figure 13 This is a schematic diagram of the geodesic distance field of a curved surface in one embodiment of this application;

[0078] Figure 14 This is a schematic diagram of the contour lines of the geodesic distance field and the projected coordinates of the frequency-selective units on the contour lines in one embodiment of this application;

[0079] Figure 15 These are oblique and top views of the frequency-selected surface in one embodiment of this application;

[0080] Figure 16 This is a schematic diagram of the layout device of the frequency selection unit in one embodiment of this application;

[0081] Figure 17 This is a schematic diagram of the device structure of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0082] The invention will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are described merely to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0083] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment".

[0084] Curved frequency selective radomes are composite structures combining traditional pure dielectric transparent radomes and frequency selective surfaces. They enable effective control of electromagnetic wave phase, polarization, and propagation modes at the subwavelength scale, making them core components for achieving high-performance electromagnetic protection and stealth in new airborne / missile-borne radar antennas. They hold significant importance and value in national defense and microwave communications. Radomes are typically located at the nose of aircraft and usually employ curved surfaces with excellent aerodynamic performance, such as von Kármán radomes or tangential oval radomes. These surfaces are non-developable, making it impossible to achieve planar periodic arrays of frequency elements. Arranging frequency selective elements on their surface has always been a core design challenge for curved frequency selective radomes.

[0085] To address this issue, this embodiment provides a layout method for frequency selection units, such as... Figure 1 As shown, this method is applied to the server side of a frequency-selective cell layout and includes the following steps:

[0086] 101. Obtain the geodesic distance field of the target surface calculated along the heat conduction direction.

[0087] For planar structures, the distance between frequency-selective elements in a periodic arrangement is defined as the Euclidean distance, and a periodic layout can be achieved by translating the frequency-selective elements. However, for complex curved surfaces that are not developable, the distance between frequency-selective elements is defined as the geodesic distance, and calculating the geodesic distance of the surface is a prerequisite for arranging frequency-selective elements on complex curved surfaces.

[0088] In this embodiment, the geodesic distance field is the distance field formed by the shortest path length between two nodes on the target surface. Since heat always travels along the shortest path direction on the surface, the distance calculated along the heat conduction direction is the geodesic distance field of the surface. Traditional geodesic distance field calculations mainly rely on graph algorithms, which are not only computationally inefficient but can also only calculate the geodesic distance between two points on the surface, making them unsuitable for the arrangement of surface frequency-selective units. This embodiment proposes using the heat conduction direction determined by the heat conduction equation to calculate the geodesic distance field of complex surfaces, enabling rapid calculation of the geodesic distances corresponding to point heat sources and line heat sources, thus meeting the arrangement requirements of surface frequency-selective units.

[0089] Specifically, the process of calculating the geodesic distance field of the target surface along the heat conduction direction mainly includes steps such as surface discretization, topological information reconstruction, normalized gradient field calculation, and geodesic distance field calculation. The surface discretization process mainly transforms the continuous, smooth target surface into a discrete surface approximated by a triangular mesh. The topological information reconstruction process mainly calculates the heat conduction equation on the discrete surface. The normalized gradient field process mainly calculates the normalized gradient field of the discrete surface based on the heat conduction equation. The geodesic distance field calculation process mainly determines the heat conduction direction within the normalized gradient field of the discrete surface.

[0090] 102. The projection coordinates of the frequency-selective unit are obtained by calculating the projection coordinates of the geodesic distance field on the contour lines of the geodesic distance field.

[0091] In this embodiment, the projected coordinates of the frequency-selective units (FSELECT units) are their positions on the target surface, typically defined as the center position of the projected FSELECT units. This means that the projected coordinates determine the distribution characteristics of the FSELECT units on the target surface. To ensure that the FSELECT units are projected as periodically as possible, the computer may distribute the projected coordinates evenly on the target surface. Here, the projected coordinates are calculated based on the contour lines of the geodesic range field. This process mainly includes the calculation of the contour lines of the geodesic range field and the calculation of the projected coordinates of the FSELECT units.

[0092] In this context, contour lines are lines formed by connecting isopleths in the geodetic distance field that meet distance conditions. The distance condition is that the geodetic distance in the geodetic distance field is the same as a pre-set reference distance, which is the periodic arrangement distance of the frequency-selective cells. In other words, the calculation of contour lines in the geodetic distance field requires a pre-set reference distance, which serves as the basis for determining isopleths in the geodetic distance field. For each point in the geodetic distance field, if its geodetic distance is the same as the pre-set reference distance, then that point is an isopleth that meets the distance conditions. Connecting the isopleths in the geodetic distance field that meet the distance conditions yields the contour lines of the geodetic distance field.

[0093] It should be noted that the contour lines of the geodesic distance field are formed by traversing all points on the discrete surface and connecting the contour points that satisfy the distance conditions. Considering the different directions of heat source propagation in the target surface, if the direction of heat source propagation in the target surface is non-spherical, boundary asymmetry will occur, leading to the contour lines intersecting the boundary. In this case, the contour lines of the geodesic distance field are open loops. If the direction of heat source propagation in the target surface is spherical, there will be no boundary asymmetry, and the contour lines of the geodesic distance field are closed loops.

[0094] Specifically, in the process of calculating the projected coordinates of the geodesic distance field on its contour lines, frequency-selective cells can be distributed along these contour lines based on a pre-set reference distance. This ensures that the frequency-selective cells are uniformly projected onto the contour lines, thus obtaining their projected coordinates. By calculating the contour lines and projected coordinates of the target surface, quasi-periodic uniformly distributed frequency-selective cell projected coordinates can be obtained on any complex surface. The frequency-selective surface can then be obtained by projecting these frequency-selective cells.

[0095] The key reason why traditional surface frequency-selective structure design methods cannot achieve quasi-periodic arrangement of curved surfaces is that the projection coordinates cannot be determined. The present invention uses the geodesic distance field of discrete curved surfaces to calculate the projection coordinates, which breaks through the technical bottleneck of traditional methods and provides a feasible technical approach for the design of conformal frequency-selective surfaces.

[0096] 103. Project the frequency selection unit point by point onto the target surface according to the projection coordinates of the frequency selection unit to obtain a frequency selection surface with quasi-periodic arrangement of the frequency selection units.

[0097] Understandably, after obtaining the projection coordinates, the frequency-selective unit structure needs to be projected onto the curved surface to form a conformal frequency-selective surface. This process mainly includes establishing a local coordinate system and projecting the frequency-selective units. By establishing a local coordinate system, a local coordinate system can be established at the arrangement position of the frequency-selective units on the discrete curved surface to clarify the projection attitude of the frequency-selective units on the target curved surface. By projecting the frequency-selective units, the frequency-selective units can be projected onto the target curved surface according to their arrangement position, thereby obtaining the conformal curved surface frequency-selective surface of the radome.

[0098] In practical applications, the two processes of establishing a local coordinate system and projecting the frequency-selective element can be implemented by calling 3D modeling software through a programming language. For example, joint modeling can be achieved by calling the modeling function in the 3D modeling software. By adopting the joint modeling approach, on the one hand, the frequency-selective element projection can be quickly realized by directly using the geometric calculation function of the 3D modeling software. On the other hand, the conformal frequency-selective surface obtained by modeling can be directly imported into electromagnetic simulation software to perform full-wave simulation analysis of the surface, which is convenient for evaluating the design effectiveness.

[0099] Compared to the frequency selection unit layout method provided in this application, which achieves periodic layout of frequency selection units through planar offset of the frequency selection unit structure, this application obtains the geodesic distance field of the target surface calculated along the heat conduction direction. The geodesic distance field is the distance field formed by the shortest path length between two nodes on the target surface. The projection coordinates of the frequency selection units are obtained by calculating the projection coordinates on the contour lines of the geodesic distance field. The contour lines are the lines formed by connecting the contour points in the geodesic distance field that meet the distance conditions. The distance condition is that the geodesic distance in the geodesic distance field is the same as the preset reference distance. The reference distance is the periodic arrangement distance of the frequency selection units. The frequency selection units are projected point by point onto the target surface according to the projection coordinates of the frequency selection units to obtain the frequency selection surface with quasi-periodic arrangement of the frequency selection units. The entire process calculates the geodesic distance field of the target surface along the heat conduction direction, which enables the rapid calculation of the geodesic distance corresponding to the heat source, meets the arrangement requirements of the frequency-selective unit on the surface, and calculates the projected coordinates of the frequency-selective unit by combining the distance field of the measuring point, so that the frequency-selective unit is distributed as evenly as possible on the surface, thereby realizing the quasi-periodic layout of the frequency-selective unit on the complex surface.

[0100] It is understandable that the placement of traditional planar periodic elements can be achieved through coordinate translation. However, for non-developable complex surfaces, the placement of frequency-selective elements cannot be obtained through coordinate translation. This embodiment proposes to calculate the placement of frequency-selective elements using a geodesic distance field, which allows the frequency-selective elements to be distributed as evenly as possible on the surface. Specifically, for example... Figure 2 As shown, step 101 includes the following steps:

[0101] 201. Convert the target surface into a discrete surface approximated by a triangular mesh, so as to describe the geometric features of the corresponding three-dimensional structure of the target surface through the triangular mesh.

[0102] 202. Calculate the heat conduction direction of the discrete surface based on the temperature field of the discrete surface.

[0103] 203. Calculate the geodesic distance field of the target surface along the heat conduction direction of the discrete surface.

[0104] In this embodiment, converting the target surface into a discrete surface approximated by a triangular mesh can be achieved using 3D modeling software. The software exports a corresponding file format that describes the surface geometry of the 3D object, allowing the triangular mesh to describe the geometric features of the corresponding 3D structure of the target surface. Specifically, as shown... Figure 3 As shown, Figure 3The diagram shows a discrete surface obtained by discretizing the target surface into a triangular mesh. Here, the temperature field of the discrete surface is obtained by discretizing and calculating the heat conduction equation at the mesh nodes on the discrete surface. The heat conduction equation describes the rate of temperature change with time on the discrete surface. In other words, based on obtaining the triangular mesh corresponding to the discrete surface, the heat conduction equation needs to be discretized and calculated at the mesh nodes corresponding to the triangular mesh. The generalized heat conduction equation can be expressed as the following formula:

[0105] v t =Δv

[0106] Among them, v t Let v be the rate of change of temperature with respect to time on the surface, v be the temperature, and v be the Laplace operator. The temperature field of the discrete surface can be obtained through the heat conduction equation.

[0107] Furthermore, based on obtaining the temperature field of the discrete surface, it is necessary to calculate the heat conduction direction of the discrete surface. Specifically, in the process of calculating the heat conduction direction of the discrete surface based on its temperature field, the normalized gradient field of the discrete surface can be calculated; the opposite direction of the temperature gradient in the normalized gradient field is selected as the heat conduction direction of the discrete surface. Here, the heat conduction direction is realized through the normalized gradient field. Assuming the normalized gradient field is X, it can be expressed as follows:

[0108]

[0109] in, This is the gradient operator. When calculating the normalized gradient field, improper settings of the heat source and boundary conditions can lead to non-convergence, especially in regions far from the heat source on the discrete surface. Because the temperature gradient is small in these regions, calculating the opposite direction of the temperature gradient field in the normalized gradient field can easily result in large errors.

[0110] Furthermore, in order to improve the accuracy of geodesic distance field calculation, it is necessary to check the normalized gradient field of the discrete surface after it has been calculated. If the fluctuation of the normalized gradient field of the discrete surface increases in the region far from the heat source, the boundary conditions and initial conditions far from the heat source should be readjusted until a stable normalized gradient field is obtained.

[0111] Accordingly, in a stable normalized gradient field, the opposite direction of the temperature gradient is selected as the heat conduction direction of the discrete surface. Based on the normalized gradient field, the geodesic distance field of the discrete surface is calculated, as shown in the following formula:

[0112]

[0113] Where φ is the geodesic distance field of the discrete surface. It is the divergence operator. According to the relevant theories of discrete geometry, a triangular mesh on a discrete surface corresponds to a mesh node i, and its Laplacian operator, gradient operator, and discrete operator can be expressed by the following formula:

[0114]

[0115] Among them, A i It is one-third of the total area of ​​the triangle surrounding vertex i, j is the index of the adjacent vertices surrounding vertex i, and v is the diagonal of the line connecting vertices i and j. i and v j These are the temperature values ​​at vertices i and j, respectively; A f N is the area of ​​the triangular mesh. i It is the normal vector of the triangular mesh, e i X is the vector of the side opposite vertex i in the triangle (counterclockwise); j Let θ1 and θ2 be the normalized vectors of the triangle adjacent to vertex i, and let e1 and e2 be the two edge vectors, with θ1 and θ2 being the diagonals opposite edges e1 and e2. The geodesic distance field information at the grid vertices can be obtained using the above formula. For triangular grids, three-point linear interpolation can be used. The geodesic distance field of any surface can be calculated using the above equation.

[0116] In practical applications, the calculation process of the geodesic distance field of the target surface is as follows: Figure 4 As shown, specifically in Figure 4 First, the target surface is converted into a discrete surface approximated by a triangular mesh. Then, the heat conduction equation of the discrete surface is calculated by setting boundary conditions. Based on the heat conduction equation, the normalized gradient field of the discrete surface is calculated. The normalized gradient field of the discrete surface is checked for errors. If there are errors, the boundary is adjusted and the heat conduction equation of the discrete surface is recalculated. Otherwise, the geodesic distance is calculated in the normalized gradient field.

[0117] Understandably, the key difficulty in achieving quasi-periodic arrangement of curved surfaces using traditional surface frequency-selective structure design methods lies in the inability to determine the projection coordinates. This invention proposes a method for calculating projection coordinates using the geodesic distance field of the curved surface, breaking through the technical bottleneck of traditional methods and providing a feasible technical approach for the design of conformal frequency-selective surfaces. Specifically, as follows... Figure 5 As shown, step 102 includes the following steps:

[0118] 301. Based on the geodesic distance field of the target surface, determine the contour lines of the geodesic distance field according to the pre-set reference distance.

[0119] 302. Traverse the contour lines of the geodetic distance field, and calculate the projection coordinates on the contour lines according to the preset reference distance to obtain the projection coordinates of the frequency-selective unit.

[0120] In this embodiment, the reference distance is equivalent to the periodic arrangement distance of the frequency-selective cells. Specifically, in the process of calculating the contour lines of the geodetic distance, the reference distance is assumed to be d. p Then the projected coordinates of the frequency-selective unit are at a certain distance d. p On contour lines that are integer multiples of each other, considering that the discrete curve is actually approximated by a series of triangular meshes, the contour lines on the discrete surface are actually composed of the intercepts of a set of triangles. For a single triangle on the discrete surface, assuming that the vertices of the triangle are P1, P2, and P3, and the geodesic distances corresponding to the vertices are φ1, φ2, and φ3, if the triangle intersects with the contour lines, then the contour lines and the sides of the triangle must have two intersection points. The coordinates of these intersection points can be calculated using the following formula:

[0121]

[0122] Among them, P c φ is the intersection of the triangle and the contour lines. c The measured distance corresponding to the isopleth points on the contour line is d. p The contour lines are integer multiples of the given contour lines. According to the above contour line calculation rules, the contour lines of the geodesic distance field on the discrete surface can be obtained by traversing all triangular meshes.

[0123] In this embodiment, the contour lines of the geodesic distance field are divided into two types: open-loop contour lines and closed-loop contour lines. Closed-loop contour lines form a closed curve with its beginning and end connected, while open-loop contour lines are usually truncated by the surface boundary, forming an unclosed curve. Specifically, as follows... Figure 6 As shown, Figure 6 The diagram shows the open-loop and closed-loop contour lines formed around the heat source on a discrete surface. To ensure that the frequency-selective elements are distributed as uniformly as possible on the target surface, when performing coordinate projection calculations on the contour lines, the open-loop and closed-loop contour lines need to use different layouts. Specifically, the distribution of the frequency-selective elements on the open-loop contour lines must strictly adhere to the reference distance d. p When laying out the frequency selection unit, the distribution on the closed-loop contour line does not need to consider the relationship between the total arc length of the closed-loop contour line and the reference distance.

[0124] Specifically, during the process of traversing the contour lines of the geodetic distance field, if the contour line is a closed-loop contour line, the projection coordinates of the frequency-selective unit are calculated on the contour line according to a pre-set reference distance. This includes: when the ratio of the total arc length corresponding to the contour line to the reference distance is an integer multiple, the distribution of the frequency-selective unit on the closed-loop contour line is determined according to the reference distance, and the projection coordinates of the frequency-selective unit are obtained; when the ratio of the total arc length corresponding to the contour line to the reference distance is not an integer multiple, the reference distance is corrected, and the distribution of the frequency-selective unit on the closed-loop contour line is determined according to the corrected reference distance, and the projection coordinates of the frequency-selective unit are obtained.

[0125] For closed-loop contour lines, the distribution of frequency-selective cells on the closed-loop contour lines needs to strictly follow the reference distance d. p Layout is then performed. This layout method requires that the total arc length of the closed-loop contour lines be equal to the reference distance d. p The distance condition is an integer multiple of the given distance, but in most cases, it is difficult to satisfy the distance condition, such as... Figure 7a As shown in the left figure, according to the reference distance d p After arranging the frequency-selective cells, the distance between the starting and ending coordinates is too small. Therefore, in order to ensure that the frequency-selective cells are distributed as evenly as possible on the closed-loop contour lines, the spacing between the frequency-selective cells should be corrected as follows:

[0126]

[0127] Among them, L a N is the total arc length of the closed-loop contour lines. p The distance between the starting point and the ending point is not less than d. p The maximum number of frequency-selectable cells that can be arranged under the given conditions, d pa It is the reference distance of the frequency-selective cell after adjustment, and L a It is d pa The value should be an integer multiple of the frequency selection unit, so that the projected positions of the frequency selection units are evenly distributed on the closed-loop contour lines, such as... Figure 7a As shown in the right-hand figure, according to the reference distance d pa After adjusting the arrangement, although the reference distance of the frequency selective unit will increase, the performance of the frequency selective surface can be optimized.

[0128] Specifically, during the process of traversing the contour lines of the geodetic distance field, if the contour line is an open-loop contour line, the projection coordinates of the frequency-selective unit are calculated on the contour line according to the preset reference distance. This includes: taking one endpoint of the open-loop contour line in the geodetic distance field as the starting point for searching, determining the distribution of the frequency-selective unit on the open-loop contour line one by one according to the reference distance, and obtaining the projection coordinates of the frequency-selective unit.

[0129] For open-loop contour lines, since the boundaries of the contour lines are usually located at the boundaries of freeform surfaces, the electromagnetic properties in this region have little impact on the overall performance of the radome. The distribution of frequency-selective elements on the open-loop contour lines can be strictly based on the reference distance d. p The layout is performed by selecting one endpoint of an open-loop contour line as the starting point and searching along the contour direction. Whenever the arc length reaches the reference distance d... p At that time, the projected coordinates of a frequency-selective unit are placed, such as Figure 7b As shown, the projection layout process of the frequency-selective unit is repeated until the search of the entire open-loop contour lines is completed.

[0130] In practical applications, the process of calculating projected coordinates based on contour lines of the geodesic distance field is as follows: Figure 8 As shown, specifically in Figure 8 First, the geodesic distance field of the discrete surface is loaded. The contour lines of the geodesic distance field are calculated according to the preset reference distance. Then, all contour lines are traversed to calculate the projection coordinates. During the calculation process, it is determined whether the contour line is a closed-loop contour line. If it is, the projection coordinates of the frequency-selective unit are determined on the closed-loop contour line according to the calculation method of the closed-loop contour line. Otherwise, the projection coordinates of the frequency-selective unit are determined on the open-loop contour line according to the calculation method of the open-loop contour line. Finally, the projection coordinates of the frequency-selective unit are output.

[0131] In related technologies, the layout of curved frequency selective elements is mainly achieved through mapping. This process involves three steps: First, the frequency selective elements are periodically arranged in a plane to obtain a planar frequency selective surface. Second, the curved characteristics of the radome structure are analyzed, and a suitable projection direction is selected to reduce the distortion of the projected frequency selective surface. Finally, the planar frequency selective surface is used as the projection source, and the frequency selective surface is mapped onto the radome surface along the projection direction. In other words, while the mapping method can obtain a frequency selective surface conformal to the radome structure, the projection process from a plane to a curved surface causes shape distortion in the frequency selective element structure. Consequently, the projected frequency selective element structure cannot achieve the designed electromagnetic performance, leading to severe performance degradation of the designed frequency selective radome. To address this issue, traditional methods typically employ a curved surface segmentation projection strategy. This involves dividing the radome into multiple relatively flat regions based on its curved surface characteristics and selecting an appropriate projection direction for each region. While this strategy can reduce the distortion of the frequency-selective elements to some extent, the curved surface segments of the radome have seams, and these segments are usually determined manually, introducing a degree of randomness and making the process extremely cumbersome. Furthermore, although the curved surface segmentation strategy avoids severe distortion of the frequency-selective elements, distortion still exists within individual segmented regions. Consequently, the conformal frequency-selective surface of the radome designed in this way still struggles to achieve the desired electromagnetic performance. Therefore, how to arrange the frequency-selective elements on the surface of a curved radome remains a significant technical challenge.

[0132] Understandably, to address the severe structural distortion after projection of the aforementioned non-developable surface frequency-selective unit, this embodiment introduces a local coordinate system during the projection process of the frequency-selective unit. This local coordinate system enables the normal projection of the frequency-selective unit within a local region, significantly reducing projection distortion. Specifically, for example... Figure 9 As shown, step 103 includes the following steps:

[0133] 401. Establish a local projection coordinate system based on the projection coordinates of the frequency selection unit to determine the projection posture of the frequency selection unit on the target surface.

[0134] 402. Based on the local projection coordinate system, the frequency selection unit is locally offset and then projected point by point onto the target surface to obtain a frequency selection surface with quasi-periodic arrangement of frequency selection units.

[0135] Specifically, in establishing a local projection coordinate system based on the projection coordinates of the frequency-selective unit, the normal to the projection coordinate point can be used as the z-axis of the local coordinate system, the tangent direction of the contour line containing the projection coordinate point can be used as the x-axis, and the direction orthogonal to the x and z axes can be defined as the y-axis. The positional relationship of the projection coordinates of the frequency-selective unit in the local projection coordinate system is as follows: Figure 10 As shown.

[0136] Specifically, in the process of projecting the frequency-selective element (FME) point by point onto the target surface after local offset adjustment, the FME is stretched along the z-axis of the local coordinate system. The intersection of the stretched surface and the target surface is calculated to obtain the FME to be projected. Therefore, the FME usually needs to be offset a certain distance along the z-axis in the local coordinate system. A suitable offset distance is d. z The reference distance d p Half of, i.e., d z =d p / 2, under this condition, the stretching length of the projection unit is usually d p Correspondingly, the frequency selection unit undergoes a projection process with positional offset, as follows: Figure 11 As shown, this method can project the pattern of any frequency-selective element onto the surface of the radome.

[0137] Specifically, in practical applications using the aforementioned frequency-selective unit layout, firstly, any curved surface structure is read and exported as triangular mesh data using 3D modeling software. Then, the triangular mesh data is read, and the top point of the surface is used as the heat source. The positions of the corresponding triangular mesh and heat source vertices are selected as follows: Figure 12 As shown, the calculation process of the geodesic distance field using the above discrete surface yields the following result: Figure 13 The results shown indicate that the geodesic distance at the heat source is 0, and the distance increases along the normalized gradient direction. Then, the contour lines of the geodesic distance field are calculated according to a pre-set reference distance, and the results are as follows... Figure 14 As shown in (a), based on the obtained contour lines of the geodesic distance field, the reference distances of the frequency-selective cells on the open-loop and closed-loop contour lines are fine-tuned, and the projected coordinates of the frequency-selective cells are calculated based on the adjusted reference distances. The results are as follows. Figure 14 As shown in (b). Finally, the projected coordinates of all frequency selection units are traversed, and a local coordinate system for each frequency selection unit is established point by point. The frequency selection units are then projected point by point onto the target surface to obtain the frequency selection surface of the quasi-periodic arrangement of the frequency selection units. The oblique view and top view of this frequency selection surface are shown in Figure 1. Figure 15 As shown, Figure 15 (a) is a perspective view of the frequency selection surface. Figure 15 (b) is a top view of the frequency selection surface.

[0138] Furthermore, as Figure 1 To specifically implement the method, this application provides a layout device for a frequency selection unit, such as... Figure 16 As shown, the device includes: an acquisition unit 51, a calculation unit 52, and a projection unit 53.

[0139] The acquisition unit 51 is used to acquire the geodesic distance field of the target surface calculated along the heat conduction direction, wherein the geodesic distance field is the distance field formed by the shortest path length between two nodes on the target surface;

[0140] The calculation unit 52 is used to calculate the projected coordinates of the frequency selection unit based on the geodetic distance field on the contour lines of the geodetic distance field. The contour lines are lines formed by connecting the contour points in the geodetic distance field that meet the distance conditions. The distance conditions are that the geodetic distance in the geodetic distance field is the same as the preset reference distance. The reference distance is the periodic arrangement distance of the frequency selection unit.

[0141] Projection unit 53 is used to project the frequency selection unit point by point onto the target curved surface according to the projection coordinates of the frequency selection unit, so as to obtain a frequency selection surface with quasi-periodic arrangement of the frequency selection units.

[0142] The frequency selection unit layout device provided in this embodiment of the invention, compared with the existing technology of achieving periodic layout of frequency selection units through planar offset of the frequency selection unit structure, obtains the geodesic distance field of the target surface calculated along the heat conduction direction. The geodesic distance field is the distance field formed by the shortest path length between two nodes on the target surface. The projection coordinates of the frequency selection units are obtained by calculating the projection coordinates on the contour lines of the geodesic distance field. The contour lines are the lines formed by connecting the contour points in the geodesic distance field that meet the distance conditions. The distance condition is that the geodesic distance in the geodesic distance field is the same as the preset reference distance. The reference distance is the periodic arrangement distance of the frequency selection units. The frequency selection units are projected point by point onto the target surface according to the projection coordinates of the frequency selection units to obtain the frequency selection surface with quasi-periodic arrangement of the frequency selection units. The entire process calculates the geodesic distance field of the target surface along the heat conduction direction, which enables the rapid calculation of the geodesic distance corresponding to the heat source, meets the arrangement requirements of the frequency-selective unit on the surface, and calculates the projected coordinates of the frequency-selective unit by combining the distance field of the measuring point, so that the frequency-selective unit is distributed as evenly as possible on the surface, thereby realizing the quasi-periodic layout of the frequency-selective unit on the complex surface.

[0143] In specific application scenarios, the acquisition unit includes:

[0144] The conversion module is used to convert the target surface into a discrete surface approximated by a triangular mesh, so as to describe the geometric features of the corresponding three-dimensional structure of the target surface through the triangular mesh;

[0145] The first calculation module is used to calculate the heat conduction direction of the discrete surface based on the temperature field of the discrete surface. The temperature field of the discrete surface is obtained by discretely calculating the heat conduction equation through the grid nodes on the discrete surface. The heat conduction equation describes the rate of change of temperature with respect to time on the discrete surface.

[0146] The second calculation module is used to calculate the geodesic distance field of the target surface along the heat conduction direction of the discrete surface.

[0147] In specific application scenarios, the first computing module includes:

[0148] The calculation submodule is used to calculate the normalized gradient field of the discrete surface based on the temperature field of the discrete surface;

[0149] The selection submodule is used to select the opposite direction of the temperature gradient in the normalized gradient field of the discrete surface as the heat conduction direction of the discrete surface.

[0150] In specific application scenarios, the computing submodule is specifically used for:

[0151] After calculating the normalized gradient field of the discrete surface based on the temperature field of the discrete surface, the normalized gradient field of the discrete surface is checked.

[0152] If the fluctuation of the normalized gradient field of the discrete surface increases in the region far from the heat source, the boundary conditions and initial conditions far from the heat source are readjusted until a stable normalized gradient field is obtained.

[0153] Accordingly, the selection submodule is specifically used for:

[0154] In the stable normalized gradient field, the opposite direction of the temperature gradient is selected as the heat conduction direction of the discrete surface.

[0155] In specific application scenarios, the computing unit includes:

[0156] The determination module is used to determine the contour lines of the geodesic distance field based on the geodesic distance field of the target surface and according to a pre-set reference distance.

[0157] The third calculation module is used to traverse the contour lines of the geodetic distance field, calculate the projection coordinates on the contour lines according to the preset reference distance, and obtain the projection coordinates of the frequency selection unit.

[0158] In a specific application scenario, during the process of traversing the contour lines of the geodesic distance field, if the contour lines are closed-loop contour lines, then the third calculation module is specifically used for:

[0159] When the ratio of the total arc length corresponding to the contour line to the reference distance is an integer multiple, the distribution of the frequency selection unit on the closed-loop contour line is determined according to the reference distance, and the projected coordinates of the frequency selection unit are obtained.

[0160] When the ratio of the total arc length corresponding to the contour line to the reference distance is not an integer multiple, the reference distance is corrected, and the distribution of the frequency selection unit on the closed-loop contour line is determined according to the corrected reference distance to obtain the projected coordinates of the frequency selection unit.

[0161] During the process of traversing the contour lines of the geodesic distance field, if the contour lines are open-loop contour lines, then the third calculation module is specifically used for:

[0162] The search is performed starting from one endpoint of the open-loop contour line in the geodetic distance field. The distribution of frequency-selective units on the open-loop contour line is determined one by one according to the reference distance, and the projected coordinates of the frequency-selective units are obtained.

[0163] In specific application scenarios, the projection unit is specifically used for:

[0164] A local projection coordinate system is established based on the projection coordinates of the frequency selection unit to determine the projection posture of the frequency selection unit on the target surface;

[0165] Based on the local projection coordinate system, the frequency selection unit is locally offset and then projected point by point onto the target surface to obtain a frequency selection surface with quasi-periodic arrangement of frequency selection units.

[0166] It should be noted that other corresponding descriptions of the functional units involved in the layout device of the frequency selection unit provided in this embodiment can be found in the following references. Figure 1 The corresponding description in [the document] will not be repeated here.

[0167] Based on the above, Figure 1 Accordingly, this application embodiment also provides a storage medium storing a computer program thereon, which, when executed by a processor, implements the above-described method. Figure 1 The layout method of the frequency selection unit is shown.

[0168] Based on this understanding, the technical solution of this application can be embodied in the form of a software product. This software product can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, or portable hard drive), and includes several instructions to cause a computer device (such as a personal computer, server, or network device) to execute the methods described in the various implementation scenarios of this application.

[0169] Based on the above, Figure 1 The method shown, and Figure 16To achieve the above objectives, the present application also provides a physical device with a frequency selection unit layout, as shown in the virtual device embodiment. Specifically, this device can be a computer, smartphone, tablet, smartwatch, server, or network device, etc. The physical device includes a storage medium and a processor; the storage medium stores a computer program; the processor executes the computer program to implement the above-described... Figure 1 The layout method of the frequency selection unit is shown.

[0170] Optionally, the physical device may also include a user interface, a network interface, a camera, radio frequency (RF) circuitry, sensors, audio circuitry, a Wi-Fi module, etc. The user interface may include a display screen, input units such as a keyboard, etc., and optional user interfaces may also include USB interfaces, card reader interfaces, etc. The network interface may optionally include standard wired interfaces, wireless interfaces (such as Wi-Fi interfaces), etc.

[0171] In an exemplary embodiment, see Figure 17 The aforementioned physical device includes a communication bus, a processor, a memory, and a communication interface. It may also include input / output interfaces and a display device. The various functional units can communicate with each other via the bus. The memory stores a computer program, and the processor executes the program stored in the memory, performing the frequency selection unit layout method described in the above embodiments.

[0172] Those skilled in the art will understand that the physical device structure of the frequency selection unit layout provided in this embodiment does not constitute a limitation on the physical device, and may include more or fewer components, or combine certain components, or have different component arrangements.

[0173] The storage medium may also include an operating system and a network communication module. The operating system is a program that manages the hardware and software resources of the physical device in which the frequency selection unit is arranged, supporting the operation of information processing programs and other software and / or programs. The network communication module is used to enable communication between the various components within the storage medium, as well as communication with other hardware and software in the information processing physical device.

[0174] Through the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware platforms, or it can be implemented by hardware. By applying the technical solution of this application, compared with the existing methods, this application can realize the rapid calculation of the geodesic distance corresponding to the heat source by calculating the geodesic distance field of the target surface along the heat conduction direction, which meets the arrangement requirements of the frequency selection unit on the curved surface. By combining the distance field of the measuring point to calculate the projection coordinates of the frequency selection unit, the frequency selection unit is distributed as evenly as possible on the curved surface, thereby realizing the quasi-periodic layout of the frequency selection unit on the complex curved surface.

[0175] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing this application. Those skilled in the art will understand that the modules in the apparatus of the embodiment can be distributed within the apparatus of the embodiment as described, or can be modified to be located in one or more apparatuses different from this embodiment. The modules of the above-described embodiment can be combined into one module, or further divided into multiple sub-modules.

[0176] The serial numbers in this application are for descriptive purposes only and do not represent the superiority or inferiority of any particular implementation scenario. The above disclosures are merely a few specific implementation scenarios of this application; however, this application is not limited thereto, and any variations conceived by those skilled in the art should fall within the protection scope of this application.

Claims

1. A layout method for frequency-selective cells, characterized in that, include: Obtain the geodesic distance field of the target surface calculated along the heat conduction direction. The geodesic distance field is the distance field formed by the shortest path length between two nodes on the target surface. The projection coordinates of the frequency selection unit are obtained by calculating the projection coordinates of the geodetic distance field on the contour lines of the geodetic distance field. The contour lines are lines formed by connecting the contour points in the geodetic distance field that meet the distance conditions. The distance conditions are that the geodetic distance in the geodetic distance field is the same as the preset reference distance. The reference distance is the periodic arrangement distance of the frequency selection unit. Based on the projection coordinates of the frequency selection unit, the frequency selection unit is projected point by point onto the target surface to obtain a frequency selection surface with quasi-periodic arrangement of the frequency selection units.

2. The method according to claim 1, characterized in that, The acquisition of the geodesic distance field of the target surface calculated along the heat conduction direction includes: The target surface is converted into a discrete surface approximated by a triangular mesh, so as to describe the geometric features of the corresponding three-dimensional structure of the target surface through the triangular mesh; Based on the temperature field of the discrete surface, the heat conduction direction of the discrete surface is calculated. The temperature field of the discrete surface is obtained by discretizing and calculating the heat conduction equation through the grid nodes on the discrete surface. The heat conduction equation describes the rate of change of temperature with respect to time on the discrete surface. Calculate the geodesic distance field of the target surface along the heat conduction direction of the discrete surface.

3. The method according to claim 2, characterized in that, The step of calculating the heat conduction direction of the discrete surface based on the temperature field of the discrete surface includes: Calculate the normalized gradient field of the discrete surface based on the temperature field of the discrete surface; In the normalized gradient field of the discrete surface, the opposite direction of the temperature gradient is selected as the heat conduction direction of the discrete surface.

4. The method according to claim 3, characterized in that, After calculating the normalized gradient field of the discrete surface based on the temperature field of the discrete surface, the method further includes: The normalized gradient field of the discrete surface is checked; If the fluctuation of the normalized gradient field of the discrete surface increases in the region far from the heat source, the boundary conditions and initial conditions far from the heat source are readjusted until a stable normalized gradient field is obtained. Accordingly, selecting the opposite direction of the temperature gradient in the normalized gradient field of the discrete surface as the heat conduction direction of the discrete surface includes: In the stable normalized gradient field, the opposite direction of the temperature gradient is selected as the heat conduction direction of the discrete surface.

5. The method according to claim 1, characterized in that, The step of calculating the projected coordinates of the frequency-selective unit based on the projected coordinates of the geodesic range field on the contour lines of the geodesic range field includes: Based on the geodesic distance field of the target surface, the contour lines of the geodesic distance field are determined according to a pre-set reference distance; Traverse the contour lines of the geodetic distance field, and calculate the projected coordinates of the frequency-selective unit by performing projection coordinate calculations on the contour lines according to a pre-set reference distance.

6. The method according to claim 5, characterized in that, During the process of traversing the contour lines of the geodetic distance field, if the contour lines are closed-loop contour lines, then the calculation of projection coordinates on the contour lines according to a pre-set reference distance to obtain the projection coordinates of the frequency-selective unit includes: When the ratio of the total arc length corresponding to the contour line to the reference distance is an integer multiple, the distribution of the frequency selection unit on the closed-loop contour line is determined according to the reference distance, and the projected coordinates of the frequency selection unit are obtained. When the ratio of the total arc length corresponding to the contour line to the reference distance is not an integer multiple, the reference distance is corrected, and the distribution of the frequency selection unit on the closed-loop contour line is determined according to the corrected reference distance to obtain the projected coordinates of the frequency selection unit; During the process of traversing the contour lines of the geodetic distance field, if the contour lines are open-loop contour lines, then the calculation of projection coordinates on the contour lines according to a pre-set reference distance to obtain the projection coordinates of the frequency-selective unit includes: The search begins with one endpoint of the open-loop contour line in the geodetic distance field. The distribution of frequency-selective units on the open-loop contour line is determined one by one according to the reference distance, and the projected coordinates of the frequency-selective units are obtained.

7. The method according to any one of claims 1-6, characterized in that, The step of projecting the frequency selection units point by point onto the target surface according to their projection coordinates to obtain a frequency selection surface with quasi-periodic arrangement of the frequency selection units includes: A local projection coordinate system is established based on the projection coordinates of the frequency selection unit to determine the projection posture of the frequency selection unit on the target surface; Based on the local projection coordinate system, the frequency selection unit is locally offset and then projected point by point onto the target surface to obtain a frequency selection surface with quasi-periodic arrangement of frequency selection units.

8. A layout device for a frequency selection unit, characterized in that, include: The acquisition unit is used to acquire the geodesic distance field of the target surface calculated along the heat conduction direction, wherein the geodesic distance field is the distance field formed by the shortest path length between two nodes on the target surface; The calculation unit is used to calculate the projected coordinates of the frequency selection unit based on the geodetic distance field on the contour lines of the geodetic distance field. The contour lines are lines formed by connecting the contour points in the geodetic distance field that meet the distance conditions. The distance conditions are that the geodetic distance in the geodetic distance field is the same as the preset reference distance. The reference distance is the periodic arrangement distance of the frequency selection unit. The projection unit is used to project the frequency selection unit point by point onto the target curved surface according to the projection coordinates of the frequency selection unit, so as to obtain a frequency selection surface with quasi-periodic arrangement of the frequency selection units.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the layout method of the frequency selection unit according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the layout method of the frequency selection unit according to any one of claims 1 to 7.

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