Layout method, device and equipment of frequency selection unit

Abstract

The invention discloses a layout method, device and equipment for frequency selection units, relates to the technical field of communication, and can perform projection coordinate calculation on the frequency selection units in combination with a measuring point distance field, so that the frequency selection units are uniformly distributed on a curved surface as far as possible. The method comprises the following steps: obtaining a geodesic distance field of a target curved surface calculated along a heat conduction direction, wherein the geodesic distance field is a distance field formed by the shortest path length between two nodes on the target curved surface; projection coordinate calculation is carried out on a contour line of the geodesic distance field according to the geodesic distance field, projection coordinates of the frequency selection unit are obtained, the contour line is a line formed by connecting equivalent points meeting the distance condition in the geodesic distance field, and 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 a periodic arrangement distance of the frequency selection units; and projecting the frequency selection units to a target curved surface point by point according to the projection coordinates of the frequency selection units to obtain the frequency selection surface of the quasi-periodic arrangement of the frequency selection units.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a layout method, device and equipment for a frequency selection unit. Background Art

[0002] The frequency selective surface is composed of periodically arranged metal patch units or periodically arranged open hole units on a metal screen. It can effectively control the phase, polarization mode, propagation mode and other characteristics of electromagnetic waves at sub-wavelength sizes. It is the key to achieving high-performance electromagnetic protection and stealth for airborne / missile-borne radar antennas.

[0003] In the related art, the frequency selective surface of the traditional planar configuration can achieve a periodic layout through the planar offset of the frequency selective unit structure. 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 surfaces with non-developable characteristics, it is impossible to obtain the layout setting of the frequency selective unit through coordinate translation, which makes it difficult to achieve a quasi-periodic layout of the frequency selective unit on the non-developable complex surface. Summary of the invention

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

[0005] According to a first aspect of the present application, a layout method of a frequency selection unit is provided, comprising:

[0006] Acquire a geodesic distance field of a target surface calculated along a heat conduction direction, wherein the geodesic distance field is a distance field formed by the shortest path length between two nodes on the target surface;

[0007] Calculating projection coordinates on the contour lines of the geodesic distance field according to the geodesic distance field to obtain projection coordinates of the frequency selection unit, wherein the contour lines are lines formed by connecting the equivalued points in the geodesic distance field that meet the distance condition, wherein the distance condition is that the geodesic distance in the geodesic distance field is the same as a preset reference distance, and the reference distance is the periodic arrangement distance of the frequency selection unit;

[0008] The frequency selective unit is projected point by point onto a target curved surface according to the projection coordinates of the frequency selective unit, so as to obtain a frequency selective surface in which the frequency selective units are quasi-periodically arranged.

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

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

[0011] Calculating the heat conduction direction of the discrete surface according to the temperature field of the discrete surface, wherein the temperature field of the discrete surface is obtained by discretely calculating the heat conduction equation of the grid nodes on the discrete surface, and the heat conduction equation describes the rate of change of temperature on the discrete surface with respect to time;

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

[0013] Furthermore, the calculating the heat conduction direction of the discrete surface according to the temperature field of the discrete surface includes:

[0014] Calculate the normalized gradient field of the discrete surface according to the temperature field of the discrete surface;

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

[0016] Further, after calculating the normalized gradient field of the discrete surface according to the temperature field of the discrete surface, the method further includes:

[0017] checking the normalized gradient field of the discrete surface;

[0018] If the fluctuation of the normalized gradient field of the discrete surface increases in the area 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] Correspondingly, the 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] The opposite direction of the temperature gradient in the stable normalized gradient field is selected as the heat conduction direction of the discrete surface.

[0021] Further, the calculating of projection coordinates on the contour lines of the geodesic distance field according to the geodesic distance field to obtain the projection coordinates of the frequency selection unit includes:

[0022] Based on the geodesic distance field of the target surface, determining the contour lines of the geodesic distance field according to a preset reference distance;

[0023] The contour lines of the geodesic distance field are traversed, and projection coordinates are calculated on the contour lines according to a preset reference distance to obtain projection coordinates of the frequency selection unit.

[0024] Further, in the process of traversing the contour lines of the geodesic distance field, if the contour lines are closed-loop contour lines, performing projection coordinate calculation on the contour lines according to a preset reference distance to obtain projection coordinates of the frequency selection unit 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 to obtain the projection coordinates of the frequency selection unit;

[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 projection coordinates of the frequency selection unit;

[0027] In the process of traversing the contour lines of the geodesic distance field, if the contour lines are open-loop contour lines, performing projection coordinate calculation on the contour lines according to a preset reference distance to obtain projection coordinates of the frequency selection unit includes:

[0028] The search is performed with one end point of the open loop contour line in the geodesic distance field as a starting point, and the distribution of the frequency selection units on the open loop contour line is determined one by one according to the reference distance to obtain the projection coordinates of the frequency selection units.

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

[0030] Establishing a local projection coordinate system according to the projection coordinates of the frequency selection unit to determine the projection posture of the frequency selection unit on the target surface;

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

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

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

[0034] a calculation unit, configured to calculate projection coordinates of a frequency selection unit on a contour line of the geodesic distance field according to the geodesic distance field, wherein the contour line is a line formed by connecting equivalued points in the geodesic distance field that meet a distance condition, wherein the distance condition is that the geodesic distance in the geodesic distance field is the same as a preset reference distance, and the reference distance is a periodic arrangement distance of the frequency selection unit;

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

[0036] Furthermore, the acquisition unit includes:

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

[0038] A first calculation module is used to calculate the heat conduction direction of the discrete surface according to the temperature field of the discrete surface, wherein the temperature field of the discrete surface is obtained by discretely calculating the heat conduction equation of the grid nodes on the discrete surface, and the heat conduction equation describes the rate of change of temperature on the discrete surface with respect to time;

[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 calculation module includes:

[0041] A calculation submodule, used for calculating the normalized gradient field of the discrete surface according to 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 curved surface according to the temperature field of the discrete curved surface, checking the normalized gradient field of the discrete curved surface;

[0045] If the fluctuation of the normalized gradient field of the discrete surface increases in the area 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] The opposite direction of the temperature gradient in the stable normalized gradient field is selected as the heat conduction direction of the discrete surface.

[0048] Furthermore, the calculation unit comprises:

[0049] A determination module, configured to determine the contour lines of the geodesic distance field according to a preset reference distance based on the geodesic distance field of the target surface;

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

[0051] Further, in the process of traversing the contour lines of the geodesic distance field, if the contour lines are closed-loop contour lines, the third calculation module is specifically configured to:

[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 to obtain the projection coordinates of the frequency selection unit;

[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 projection coordinates of the frequency selection unit;

[0054] In the process of traversing the contour lines of the geodesic distance field, if the contour lines are open-loop contour lines, the third calculation module is specifically configured to:

[0055] The search is performed with one end point of the open loop contour line in the geodesic distance field as a starting point, and the distribution of the frequency selection units on the open loop contour line is determined one by one according to the reference distance to obtain the projection coordinates of the frequency selection units.

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

[0057] Establishing a local projection coordinate system according to the projection coordinates of the frequency selection unit to determine the projection posture of the frequency selection unit on the target surface;

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

[0059] According to a third aspect of the present application, a computer device is provided, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method described in the first aspect when executing the computer program.

[0060] According to a fourth aspect of the present application, a readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in the first aspect are implemented.

[0061] By means of the above technical scheme, the present application provides a layout method, device and equipment for a frequency selection unit. Compared with the current prior art method of realizing the periodic layout of the frequency selection unit by plane offset of the frequency selection unit structure, the present application obtains the geodesic distance field of the target surface by calculating along the heat conduction direction. The geodesic distance field is a distance field formed by the shortest path length between two nodes on the target surface. The projection coordinates of the frequency selection unit are calculated on the contour lines of the geodesic distance field according to the geodesic distance field to obtain the projection coordinates of the frequency selection unit. The contour lines are lines formed by connecting the equivalued 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 a frequency selection surface with quasi-periodic arrangement of the frequency selection unit. The whole process calculates the geodesic distance field of the target surface along the direction of heat conduction, which can realize the rapid calculation of the geodesic distance corresponding to the heat source, meet the arrangement requirements of the surface frequency selection unit, and calculate the projection coordinates of the frequency selection unit in combination with the measuring point distance field, so that the frequency selection unit is distributed on the surface as evenly as possible, thereby realizing the quasi-periodic layout of the frequency selection unit on the complex surface.

[0062] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0064] Figure 1 is a flow chart of a layout method of a frequency selection unit in an embodiment of the present application;

[0065] Figure 2 yes Figure 1 A schematic flow chart of a specific implementation of step 101;

[0066] Figure 3 is a discrete surface diagram of a triangular mesh obtained by discretizing a target surface in an embodiment of the present application;

[0067] Figure 4is a flowchart of a calculation process of a geodesic distance field of a target surface in an embodiment of the present application;

[0068] Figure 5 yes Figure 1 A schematic flow chart of a specific implementation of step 102;

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

[0070] Figure 7a is a schematic diagram of the distribution of projection points of frequency selection units on a closed loop contour line in one embodiment of the present application;

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

[0072] Figure 8 is a flowchart of a process for calculating projection coordinates based on contour lines of a geodesic distance field in one embodiment of the present application;

[0073] Fig. 9 yes Figure 1 A schematic flow chart of a specific implementation of step 103;

[0074] Fig.10 is a schematic diagram of the positional relationship of the projection coordinates of the frequency selection unit in the local projection coordinate system in one embodiment of the present application;

[0075] Fig.11 is a schematic diagram of the projection process of the frequency selection unit after position shifting in one embodiment of the present application;

[0076] Fig.12 is a schematic diagram of the position selection of the triangular mesh and the heat source vertices in one embodiment of the present application;

[0077] Fig.13 is a schematic diagram of a geodesic distance field of a curved surface in one embodiment of the present application;

[0078] Fig.14 It is a schematic diagram of the contour lines of the geodesic distance field and the projection coordinates of the frequency selection units on the contour lines in one embodiment of the present application;

[0079] Fig.15 is an oblique view and a top view of a frequency selection surface in one embodiment of the present application;

[0080] Fig.16 It is a structural schematic diagram of a layout device of a frequency selection unit in an embodiment of the present application;

[0081] Fig.17 It is a schematic diagram of the device structure of a computer device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0082] Now the content of the present invention will be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the content of the present invention, rather than implying any limitation on the scope of the present invention.

[0083] As used herein, the term "including" and variations thereof are to be interpreted as open-ended terms meaning "including but not limited to." The term "based on" is to be interpreted as "based, at least in part, 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] The curved frequency selective radome is a composite structure of a traditional pure dielectric wave-transmitting radome and a frequency selective surface. It can effectively control the phase, polarization mode, propagation mode and other characteristics of electromagnetic waves at a sub-wavelength scale. It is a core component for new airborne / missile-borne radar antennas to achieve high-performance electromagnetic protection and stealth, and has important significance and value in the fields of national defense security and microwave communications. The radome is usually located at the head of the aircraft, and its structure usually adopts a curved surface structure with excellent aerodynamic performance, such as a von Karman-shaped radome, a tangent oval-shaped radome, etc. This type of curved surface has a non-developable characteristic, which makes it impossible to realize a planar periodic array of frequency units on it. How to arrange frequency selective units on its surface has always been the core issue of the design of curved frequency selective radomes.

[0085] In order to solve this problem, this embodiment provides a layout method of a frequency selection unit, such as Figure 1 As shown, the method is applied to the server side of the frequency selection unit 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 units in periodic arrangement is defined as the Euclidean distance, and a periodic layout can be achieved by translating the frequency-selective units. However, for complex surfaces with non-developability, the distance between frequency-selective units is defined as the geodesic distance, and calculating the geodesic distance of the surface is a prerequisite for arranging frequency-selective units on complex surfaces.

[0088] In this embodiment, the geodesic distance field is a distance field formed by the shortest path length between two nodes on the target surface, and heat is always transferred along the shortest path direction on the surface, so the distance calculated along the heat conduction direction is the geodesic distance field of the surface. The calculation of the traditional geodesic distance field mainly relies on the graph algorithm, which not only has low calculation efficiency, but also can only calculate the geodesic distance between two points on the surface, and cannot be used for the arrangement of the surface frequency selection unit. The present embodiment proposes to calculate the geodesic distance field of a complex surface using the heat conduction direction determined by the heat conduction equation, which can realize the rapid calculation of the geodesic distance corresponding to the point heat source and the line heat source to meet the arrangement requirements of the surface frequency selection unit.

[0089] Specifically, the process of calculating the geodesic distance field of the target surface along the direction of heat conduction mainly includes the steps of surface discretization, topological information reconstruction, normalized gradient field calculation and geodesic distance field calculation. The surface discretization process mainly converts the continuous and 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, and the geodesic distance field calculation process mainly determines the heat conduction direction in the normalized gradient field of the discrete surface.

[0090] 102. Calculate projection coordinates on the contour lines of the geodetic distance field according to the geodetic distance field to obtain projection coordinates of the frequency selection unit.

[0091] In this embodiment, the projection coordinates of the frequency selection unit are the arrangement positions of the frequency selection unit on the target surface, which are usually defined as the center position of the projected frequency selection unit, which means that the projection coordinates determine the distribution characteristics of the frequency selection unit on the target surface. In order to arrange the projections of the frequency selection units as periodically as possible, the computer of the projection coordinates may make them evenly distributed on the target surface. Here, the projection coordinates are calculated based on the contour lines of the geodesic distance field. The process mainly includes the calculation of the contour lines of the geodesic distance field and the calculation of the projection coordinates of the frequency selection unit.

[0092] Among them, the contour line is a line formed by connecting the equivalent points that meet the distance condition in the geodetic distance field, and the distance condition is that the geodetic distance in the geodetic distance field is the same as the preset reference distance, and the reference distance is the periodic arrangement distance of the frequency selection unit. In other words, the calculation process of the contour line of the geodetic distance field requires the preset reference distance, and the reference distance can be used as a basis for determining the equivalent points in the geodetic distance field. For each point in the geodetic distance field, if the geodetic distance of the point is the same as the preset reference distance, it means that the point is an equivalent point that meets the distance condition. The contour line of the geodetic distance field can be obtained by connecting the equivalent points that meet the distance condition in the geodetic distance field.

[0093] It should be noted that the contour lines of the geodesic distance field are equivalent to being formed by traversing all points on the discrete surface and connecting the equivalent points that meet the distance conditions. Considering the different propagation directions of the heat source in the target surface, if the propagation direction of the heat source in the target surface is non-spherical, boundary asymmetry will occur, which will lead to the intersection of the contour lines with the boundary. At this time, the contour lines of the geodesic distance field are open-loop. If the propagation direction of the heat source in the target surface is spherical, boundary asymmetry will not occur. At this time, the contour lines of the geodesic distance field are closed-loop.

[0094] Specifically, in the process of calculating the projection coordinates of the geodesic distance field on the contour lines of the geodesic distance field, the frequency selection unit can be distributed on the contour lines of the geodesic distance field according to the preset reference distance, so that the frequency selection unit is evenly projected onto the contour lines to obtain the projection coordinates of the frequency selection unit. By calculating the contour lines and projection coordinates of the target surface, the quasi-periodic uniformly distributed frequency selection unit projection coordinates can be obtained on any complex surface, and the surface frequency selective surface can be obtained by the subsequent projection of the frequency selection unit.

[0095] The key reason why traditional surface frequency selective structure design methods are difficult to achieve quasi-periodic arrangement of surfaces is that the projection coordinates cannot be determined. The embodiment of the present invention uses the method of calculating the projection coordinates by using the geodesic distance field of discrete surfaces, 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 selective unit point by point onto a target curved surface according to the projection coordinates of the frequency selective unit to obtain a frequency selective surface with a quasi-periodic arrangement of the frequency selective units.

[0097] It can be understood that 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 frequency selective unit projection. By establishing a local coordinate system, a local coordinate system can be established at the arrangement position of the frequency selective unit on the discrete surface to clarify the projection posture of the frequency selective unit on the target curved surface. Through the frequency selective unit projection, the frequency selective unit can be projected onto the target curved surface according to the arrangement position of the frequency selective unit, thereby obtaining a conformal curved frequency selective surface of the antenna cover.

[0098] In actual application scenarios, the two processes of establishing a local coordinate system and projecting a frequency selective unit can be implemented by calling a three-dimensional modeling software through a programming language. For example, joint modeling can be achieved by calling the modeling function in the three-dimensional modeling software. By adopting the joint modeling method, on the one hand, the frequency selective unit projection can be quickly realized with the help of the geometric calculation function of the three-dimensional modeling software. On the other hand, the conformal frequency selective surface obtained by modeling can be directly imported into the electromagnetic simulation software for full-wave simulation analysis of the surface frequency selective surface, which is convenient for evaluating the design performance.

[0099] Compared with the layout method of the frequency selection unit provided in the embodiment of the present application, which realizes the periodic layout of the frequency selection unit by plane offset of the frequency selection unit structure, the present application obtains the geodesic distance field of the target surface by calculating along the heat conduction direction, the geodesic distance field is a distance field formed by the shortest path length between two nodes on the target surface, and the projection coordinates of the frequency selection unit are calculated on the contour lines of the geodesic distance field according to the geodesic distance field to obtain the projection coordinates of the frequency selection unit, the contour lines are lines formed by connecting the equivalued points that meet the distance condition in the geodesic distance field, 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, and 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 a frequency selection surface with quasi-periodic arrangement of the frequency selection unit. The whole process calculates the geodesic distance field of the target surface along the direction of heat conduction, which can realize the rapid calculation of the geodesic distance corresponding to the heat source, meet the arrangement requirements of the surface frequency selection unit, and calculate the projection coordinates of the frequency selection unit in combination with the measuring point distance field, so that the frequency selection unit is distributed on the surface as evenly as possible, thereby realizing the quasi-periodic layout of the frequency selection unit on the complex surface.

[0100] It is understandable that the layout position of the conventional planar periodic unit can be realized by coordinate translation, but for a non-developable complex surface, the layout position of the frequency-selective unit cannot be obtained by coordinate translation. This embodiment proposes to calculate the layout position of the frequency-selective unit by using the geodesic distance field, so that the frequency-selective unit can be distributed as evenly as possible on the surface. Specifically, Figure 2 As shown, step 101 includes the following steps:

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

[0102] 202. Calculate the heat conduction direction of the discrete surface according to 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, the target surface is converted into a discrete surface approximated by a triangular mesh, which can be realized by means of a 3D modeling software. The corresponding file format is exported by the 3D modeling software. The file format can describe the surface geometry of the 3D object, so as to describe the geometric features of the 3D structure corresponding to the target surface by means of a triangular mesh. Specifically, Figure 3 As shown, Figure 3The discretized surface of the target surface is shown as a triangular mesh. The temperature field of the discrete surface is obtained by discretely calculating the heat conduction equation on the mesh nodes of the discrete surface. The heat conduction equation describes the rate of change of temperature on the discrete surface with respect to time. In other words, on the basis of obtaining the triangular mesh corresponding to the discrete surface, it is necessary to discretely calculate the heat conduction equation on 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 is the rate of change of temperature on the surface with respect to time, v is the temperature, and v is the Laplace operator. The temperature field of the discrete surface can be obtained through the heat conduction equation.

[0107] Furthermore, based on 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 according to the temperature field of the discrete surface, the normalized gradient field of the discrete surface can be calculated according to the temperature field of the discrete surface; the opposite direction of the temperature gradient in the normalized gradient field of the discrete surface is selected as the heat conduction direction of the discrete surface. Here, the heat conduction direction is realized by the normalized gradient field. Assuming that the normalized gradient field is X, the normalized gradient field can be expressed as the following formula:

[0108]

[0109] in, is the gradient operator. When calculating the normalized gradient field, if the heat source and boundary conditions are not set reasonably, the calculation will not converge, especially in the area far away from the heat source on the discrete surface. Due to the small temperature gradient, it is easy to cause large errors when calculating the opposite direction of the temperature gradient field in the normalized gradient field.

[0110] Furthermore, in order to improve the accuracy of the geodesic distance field calculation, it is necessary to check the normalized gradient field of the discrete surface after calculating it; if the fluctuation of the normalized gradient field of the discrete surface increases in the area far away from the heat source, the boundary conditions and initial conditions far away from the heat source are readjusted until a stable normalized gradient field is obtained.

[0111] Correspondingly, the opposite direction of the temperature gradient in the stable normalized gradient field 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. For details, see the following formula:

[0112]

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

[0114]

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

[0116] In actual application scenarios, the calculation process of the geodesic distance field of the target surface is as follows: Figure 4 As shown, specifically in Figure 4 In the method, the target surface is first converted into a discrete surface approximated by a triangular mesh, and 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, and it is checked whether the normalized gradient field of the discrete surface is wrong. If so, the boundary is adjusted to recalculate the heat conduction equation of the discrete surface. Otherwise, the geodesic distance is calculated in the normalized gradient field.

[0117] It is understandable that the key reason why the traditional surface frequency selective structure design method is difficult to achieve the quasi-periodic arrangement of the surface is that the projection coordinates cannot be determined. The present invention proposes a method of calculating the projection coordinates by using the geodesic distance field of the surface, which breaks through the technical bottleneck of the traditional method and provides a feasible technical approach for the design of the surface conformal frequency selective surface. Specifically, Figure 5 As shown, step 102 includes the following steps:

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

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

[0120] In this embodiment, the reference distance is equivalent to the periodic arrangement distance of the frequency selection unit. Specifically, in the process of calculating the contour line of the geodesic distance, it is assumed that the reference distance is d p , then the projection coordinates of the frequency selection unit are at a certain distance d p On the integer multiple contour lines, 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 a set of triangle intercepts. 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 has an intersection with the contour line, then the contour line and the edge of the triangle must have two intersections, and the coordinates of the intersections can be calculated according to the following formula:

[0121]

[0122] Among them, P c is the intersection of the triangle and the contour line, φ c is the measured distance corresponding to the isovalue point on the isovalue line, and its value is d p 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. The closed-loop contour lines form a closed curve connected end to end, while the open-loop contour lines are usually cut off by the surface boundary to form an unclosed curve. Figure 6 As shown, Figure 6 In the figure, the open-loop contour lines and closed-loop contour lines formed around the heat source on the discrete surface are shown. In order to make the frequency selection units as evenly distributed as possible on the target surface, when the frequency selection units perform coordinate projection calculations on the contour lines, the open-loop contour lines and closed-loop contour lines need to use different layouts of the frequency selection units, that is, the distribution of the frequency selection units on the open-loop contour lines needs to be strictly in accordance with the reference distance d. p For layout, the distribution of frequency selection units on the closed-loop contour lines does not need to consider the relationship between the total arc length corresponding to the closed-loop contour lines and the reference distance.

[0124] Specifically, in the process of traversing the contour lines of the geodetic distance field, if the contour line is a closed-loop contour line, the projection coordinate calculation is performed on the contour line according to a preset reference distance to obtain the projection coordinates of the frequency selection unit, including: 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 to obtain the projection coordinates of the frequency selection unit; 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 projection coordinates of the frequency selection unit.

[0125] For the closed-loop contour, the distribution of the frequency selection unit on the closed-loop contour needs to be strictly in accordance with the reference distance d p The premise of this layout method is that the total arc length of the closed loop contour line is the reference distance d. p However, in most cases, it is difficult to meet the distance condition, such as Figure 7a As shown in the left figure, according to the reference distance d p After the arrangement position is adjusted, the distance between the starting point coordinate and the end point coordinate is too small. Therefore, in order to make the frequency selection units distributed as evenly as possible on the closed loop contour line, the distribution spacing of the frequency selection units should be corrected as follows:

[0126]

[0127] Among them, L a is the total arc length of the closed loop contour, N p The distance between the starting point and the end point is not less than d p The maximum number of frequency-selective units that can be arranged under the premise, d pa is the reference distance of the frequency selection unit after adjustment, and L a Yes pa Integer multiples of , so that the projection position of the frequency selection unit can be evenly distributed on the closed loop contour, such as Figure 7a As shown in the figure on the right, according to the reference distance d pa After the arrangement position is adjusted, although the reference distance of the frequency selective unit will increase, the performance of the frequency selective surface can be optimized.

[0128] Specifically, in the process of traversing the contour lines of the geodesic distance field, if the contour lines are open-loop contour lines, projection coordinates are calculated on the contour lines according to a preset reference distance to obtain projection coordinates of the frequency selection unit, including: searching with one endpoint of the open-loop contour line in the geodesic distance field as a starting point, determining the distribution of the frequency selection units on the open-loop contour line one by one according to the reference distance, and obtaining the projection coordinates of the frequency selection unit.

[0129] For the open-loop contour line, since the boundary of the contour line is usually located at the boundary of the free surface, the electromagnetic performance in this area has little effect on the overall performance of the radome. The distribution of the frequency selection unit on the open-loop contour line can be strictly based on the reference distance d. p To perform layout, select an endpoint of an open loop contour line as the starting point and search along the contour direction. Whenever the arc length reaches the reference distance d p When placing a frequency selection unit projection coordinate, such as Figure 7b As shown, the projection layout process of the frequency selection unit is repeated until the entire open-loop contour search is completed.

[0130] In actual application scenarios, the process of calculating projection coordinates based on the contour lines of the geodesic distance field is as follows: Figure 8 As shown, specifically in Figure 8 In the method, the geodesic distance field of the discrete surface is first loaded, and the contour lines of the geodesic distance field are calculated according to the preset reference distance. Then, all the contour lines are traversed to calculate the projection coordinates. In the calculation process, it is determined whether the contour line is a closed-loop contour line. If so, the projection coordinates of the frequency selection 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 selection 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 selection unit are output.

[0131] In the related art, the layout of the curved frequency selection unit is mainly realized by mapping, and its implementation process mainly includes three steps: first, the frequency selection unit is arranged periodically in the plane to obtain a frequency selection surface of a plane configuration; second, the curved surface characteristics of the antenna cover structure are analyzed, and a suitable projection direction is selected on it to reduce the degree of distortion of the frequency selection surface after projection; finally, the plane frequency selection surface is used as the projection source, and the frequency selection surface is mapped to the antenna cover surface along the projection direction. In other words, the mapping method can be used to obtain a frequency selection surface conformal to the antenna cover structure, but the projection process from the plane to the curved surface will cause the shape distortion of the frequency selection unit structure, and the frequency selection unit structure after projection cannot achieve the designed electromagnetic performance, resulting in serious degradation of the performance of the designed frequency selection antenna cover. In order to solve this problem, the traditional method usually adopts a curved block projection strategy, that is, according to the curved surface characteristics of the radome, it is divided into multiple relatively flat areas, and a suitable projection direction is selected for each area. This strategy can reduce the distortion of the frequency-selective unit to a certain extent, but because there are seams in the curved surface blocks of the radome, and the curved surface blocks are usually determined manually, there is not only a certain degree of randomness, but also the operation steps are very cumbersome. In addition, although the curved surface block strategy can avoid serious distortion of the frequency-selective unit, the projected frequency-selective unit still has distortion within a single block interval, and the conformal frequency-selective surface of the radome designed in this way is still difficult to obtain the expected electromagnetic performance. Therefore, how to layout the frequency-selective unit on the surface of the curved radome is still a technical problem.

[0132] It can be understood that, in order to solve the problem of serious structural distortion after projection of the non-developable surface frequency selection unit, this embodiment introduces a local coordinate system in the projection process of the frequency selection unit, and realizes the normal projection of the frequency selection unit in the local area through the local coordinate system, which greatly reduces the projection distortion of the frequency selection unit. Specifically, Fig. 9 As shown, step 103 includes the following steps:

[0133] 401. Establish a local projection coordinate system according to 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 adjusted and then projected point by point onto a target curved surface to obtain a frequency selection surface with quasi-periodic arrangement of the frequency selection units.

[0135] Specifically, in the process of establishing the local projection coordinate system according to the projection coordinates of the frequency selection unit, the normal direction of the projection coordinate point can be used as the z-axis of the local coordinate system, the tangent direction of the contour line where the projection coordinate point is located can be used as the x-axis of the local coordinate system, and then the direction orthogonal to the x and z axes is defined as the y-axis of the local coordinate system. The position relationship of the projection coordinates of the specific frequency selection unit in the local projection coordinate system is as follows: Fig.10 shown.

[0136] Specifically, when the frequency selection unit is projected point by point onto the target surface after local offset adjustment, the frequency selection unit is stretched along the z-axis of the local coordinate system, and the frequency selection unit to be projected is obtained by calculating the intersection line between the stretched surface and the target surface. Therefore, the frequency selection unit usually needs to be offset along the z-axis in the local coordinate system. The more appropriate position offset distance d z is the reference distance d p Half of d z =d p / 2, under this condition, the stretching length of the projection unit is usually d p , accordingly, the projection process of the frequency selection unit after position shift is as follows Fig.11 As shown, the method can project any pattern of frequency-selective units onto the surface of the radome.

[0137] Specifically, in actual application scenarios, the layout of the frequency selection unit is used. First, any surface structure is read and exported as triangular mesh data using 3D modeling software. The triangular mesh data is read and the top point of the surface is used as the heat source. The position of the corresponding triangular mesh and the heat source vertex is selected as follows: Fig.12 As shown, the calculation process of the geodesic distance field of the above discrete surface is as follows Fig.13 The result shown in the figure shows 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 the preset reference distance. The result is shown in the figure Fig.14 As shown in (a), based on the contour lines of the geodesic distance field, the reference distances of the frequency selection units on the open-loop contour lines and the closed-loop contour lines are fine-tuned, and the projection coordinates of the frequency selection units are calculated based on the adjusted reference distances. The results are shown in Fig.14 Finally, the projection coordinates of all frequency-selective units are traversed, and the local coordinate system of the frequency-selective unit is established point by point. The frequency-selective unit is projected point by point onto the target surface to obtain a frequency-selective surface with quasi-periodic arrangement of frequency-selective units. The oblique view and top view of the frequency-selective surface are shown in Fig.15 As shown, Fig.15 (a) is an oblique view of the frequency selective surface. Fig.15 (b) is a top view of the frequency selective surface.

[0138] Further, as Figure 1 The specific implementation of the method, the embodiment of the present application provides a layout device of a frequency selection unit, such as Fig.16 As shown, the device includes: an acquisition unit 51, a calculation unit 52, and a projection unit 53.

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

[0140] a calculation unit 52, configured to calculate projection coordinates on a contour line of the geodesic distance field according to the geodesic distance field to obtain projection coordinates of a frequency selection unit, wherein the contour line is a line formed by connecting equivalued points in the geodesic distance field that meet a distance condition, wherein the distance condition is that the geodesic distance in the geodesic distance field is the same as a preset reference distance, and the reference distance is a periodic arrangement distance of the frequency selection unit;

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

[0142] The layout device of the frequency selection unit provided in the embodiment of the present invention is compared with the periodic layout method of the frequency selection unit in the prior art that realizes the periodic layout of the frequency selection unit by plane offset of the frequency selection unit structure. The present application obtains the geodesic distance field of the target surface by calculation along the heat conduction direction. The geodesic distance field is a distance field formed by the shortest path length between two nodes on the target surface. The projection coordinates of the frequency selection unit are calculated on the contour lines of the geodesic distance field according to the geodesic distance field to obtain the projection coordinates of the frequency selection unit. The contour lines are lines formed by connecting the equivalued points that meet the distance condition in the geodesic distance field. 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 a frequency selection surface with quasi-periodic arrangement of the frequency selection unit. The whole process calculates the geodesic distance field of the target surface along the direction of heat conduction, which can realize the rapid calculation of the geodesic distance corresponding to the heat source, meet the arrangement requirements of the surface frequency selection unit, and calculate the projection coordinates of the frequency selection unit in combination with the measuring point distance field, so that the frequency selection unit is distributed on the surface as evenly as possible, thereby realizing the quasi-periodic layout of the frequency selection unit on the complex surface.

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

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

[0145] A first calculation module is used to calculate the heat conduction direction of the discrete surface according to the temperature field of the discrete surface, wherein the temperature field of the discrete surface is obtained by discretely calculating the heat conduction equation of the grid nodes on the discrete surface, and the heat conduction equation describes the rate of change of temperature on the discrete surface with respect to time;

[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 a specific application scenario, the first calculation module includes:

[0148] A calculation submodule, used for calculating the normalized gradient field of the discrete surface according to 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 a specific application scenario, the computing submodule is specifically used for:

[0151] After calculating the normalized gradient field of the discrete curved surface according to the temperature field of the discrete curved surface, checking the normalized gradient field of the discrete curved surface;

[0152] If the fluctuation of the normalized gradient field of the discrete surface increases in the area 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] The opposite direction of the temperature gradient in the stable normalized gradient field is selected as the heat conduction direction of the discrete surface.

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

[0156] A determination module, configured to determine the contour lines of the geodesic distance field according to a preset reference distance based on the geodesic distance field of the target surface;

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

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

[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 to obtain the projection coordinates of the frequency selection unit;

[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 projection coordinates of the frequency selection unit;

[0161] In the process of traversing the contour lines of the geodesic distance field, if the contour lines are open-loop contour lines, the third calculation module is specifically configured to:

[0162] The search is performed with one end point of the open loop contour line in the geodesic distance field as a starting point, and the distribution of the frequency selection units on the open loop contour line is determined one by one according to the reference distance to obtain the projection coordinates of the frequency selection units.

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

[0164] Establishing a local projection coordinate system according to the projection coordinates of the frequency selection unit to determine the projection posture of the frequency selection unit on the target surface;

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

[0166] It should be noted that for other corresponding descriptions of the functional units involved in the layout device of the frequency selection unit provided in this embodiment, reference can be made to Figure 1 The corresponding description in will not be repeated here.

[0167] Based on the above Figure 1 The method shown in the embodiment of the present application accordingly provides a storage medium on which a computer program is stored, and when the program is executed by a processor, the above-mentioned Figure 1 The layout method of the frequency selection unit is shown.

[0168] Based on this understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each implementation scenario of the present application.

[0169] Based on the above Figure 1 The method shown, and Fig.16In order to achieve the above-mentioned purpose, the embodiment of the present application also provides a physical device for the layout of the frequency selection unit, which can be a computer, a smart phone, a tablet computer, a smart watch, a server, or a network device, etc. The physical device includes a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to achieve the above-mentioned 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, a radio frequency (RF) circuit, a sensor, an audio circuit, a WI-FI module, etc. The user interface may include a display, an input unit such as a keyboard, etc., and the optional user interface may also include a USB interface, a card reader interface, etc. The network interface may optionally include a standard wired interface, a wireless interface (such as a WI-FI interface), etc.

[0171] In an exemplary embodiment, see Fig.17 The physical device includes a communication bus, a processor, a memory and a communication interface, and may also include an input / output interface and a display device, wherein each functional unit can communicate with each other through the bus. The memory stores a computer program, and the processor is used to execute the program stored in the memory and execute the layout method of the frequency selection unit in the above embodiment.

[0172] Those skilled in the art will appreciate that the physical device structure of the layout of a frequency selection unit provided in this embodiment does not constitute a limitation on the physical device, and may include more or fewer components, or a combination of certain components, or 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 physical device hardware and software resources of the layout of the above-mentioned frequency selection unit, and supports the operation of information processing programs and other software and / or programs. The network communication module is used to realize communication between the components inside the storage medium, and communication with other hardware and software in the information processing physical device.

[0174] Through the description of the above implementation methods, those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform, or by hardware. By applying the technical solution of the present application, compared with the current existing methods, the present 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 direction of heat conduction, meet the arrangement requirements of the surface frequency selection unit, and calculate the projection coordinates of the frequency selection unit in combination with the measuring point distance field, so that the frequency selection unit is distributed as evenly as possible on the surface, thereby realizing the quasi-periodic layout of the frequency selection unit on the complex surface.

[0175] Those skilled in the art will appreciate that the accompanying drawings are only schematic diagrams of a preferred implementation scenario, and the modules or processes in the accompanying drawings are not necessarily necessary for implementing the present application. Those skilled in the art will appreciate that the modules in the devices in the implementation scenario can be distributed in the devices of the implementation scenario according to the description of the implementation scenario, or can be changed accordingly and located in one or more devices different from the present implementation scenario. The modules of the above-mentioned implementation scenario can be combined into one module, or can be further split into multiple submodules.

[0176] The above serial numbers of this application are only for description and do not represent the advantages and disadvantages of the implementation scenarios. The above disclosure is only a few specific implementation scenarios of this application, but this application is not limited to them, and any changes that can be thought of by technicians in this field should fall within the scope of protection of this application.

Claims

1. A layout method of a frequency selection unit, characterized in that: include: Acquire a geodesic distance field of a target surface calculated along a heat conduction direction, wherein the geodesic distance field is a distance field formed by the shortest path length between two nodes on the target surface; Calculating projection coordinates on the contour lines of the geodesic distance field according to the geodesic distance field to obtain projection coordinates of the frequency selection unit, wherein the contour lines are lines formed by connecting the equivalued points in the geodesic distance field that meet the distance condition, wherein the distance condition is that the geodesic distance in the geodesic distance field is the same as a preset reference distance, and the reference distance is the periodic arrangement distance of the frequency selection unit; The frequency selective unit is projected point by point onto a target curved surface according to the projection coordinates of the frequency selective unit, so as to obtain a frequency selective surface in which the frequency selective units are quasi-periodically arranged.

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

3. The method according to claim 2, characterized in that Calculating the heat conduction direction of the discrete curved surface according to the temperature field of the discrete curved surface includes: Calculate the normalized gradient field of the discrete surface according to the temperature field of the discrete surface; The opposite direction of the temperature gradient in the normalized gradient field of the discrete surface 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 according to the temperature field of the discrete surface, the method further includes: checking the normalized gradient field of the discrete surface; If the fluctuation of the normalized gradient field of the discrete surface increases in the area 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; Correspondingly, the 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: The opposite direction of the temperature gradient in the stable normalized gradient field 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 projection coordinates on the contour lines of the geodesic distance field according to the geodesic distance field to obtain projection coordinates of the frequency selection unit includes: Based on the geodesic distance field of the target surface, determining the contour lines of the geodesic distance field according to a preset reference distance; The contour lines of the geodesic distance field are traversed, and projection coordinates are calculated on the contour lines according to a preset reference distance to obtain projection coordinates of the frequency selection unit.

6. The method according to claim 5, characterized in that In the process of traversing the contour lines of the geodesic distance field, if the contour lines are closed-loop contour lines, performing projection coordinate calculation on the contour lines according to a preset reference distance to obtain projection coordinates of the frequency selection 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 to obtain the projection coordinates of the frequency selection unit; 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 projection coordinates of the frequency selection unit; In the process of traversing the contour lines of the geodesic distance field, if the contour lines are open-loop contour lines, performing projection coordinate calculation on the contour lines according to a preset reference distance to obtain projection coordinates of the frequency selection unit includes: The search is performed with one end point of the open loop contour line in the geodesic distance field as a starting point, and the distribution of the frequency selection units on the open loop contour line is determined one by one according to the reference distance to obtain the projection coordinates of the frequency selection units.

7. The method according to any one of claims 1 to 6, characterized in that The step of projecting the frequency selection unit point by point onto a target curved surface according to the projection coordinates of the frequency selection unit to obtain a frequency selection surface having a quasi-periodic arrangement of the frequency selection units comprises: Establishing a local projection coordinate system according to the projection coordinates of the frequency selection unit to determine the projection posture of the frequency selection unit on the target surface; On the basis of the local projection coordinate system, the frequency selection unit is locally offset adjusted and then projected point by point onto the target curved surface to obtain a frequency selection surface with quasi-periodic arrangement of the frequency selection units.

8. A layout device for a frequency selection unit, characterized in that: include: An acquisition unit, used to acquire a geodesic distance field of a target surface calculated along a heat conduction direction, wherein the geodesic distance field is a distance field formed by the shortest path length between two nodes on the target surface; a calculation unit, configured to calculate projection coordinates of a frequency selection unit on a contour line of the geodesic distance field according to the geodesic distance field, wherein the contour line is a line formed by connecting equivalued points in the geodesic distance field that meet a distance condition, wherein the distance condition is that the geodesic distance in the geodesic distance field is the same as a preset reference distance, and the reference distance is a periodic arrangement distance of the frequency selection unit; The projection unit is used to project the frequency selection unit point by point onto a target curved surface according to the projection coordinates of the frequency selection unit to obtain a frequency selection surface with a 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, wherein: When the processor executes the computer program, the steps of the method for arranging the frequency selection unit according to any one of claims 1 to 7 are implemented.

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

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