CN117350083B - Method and device for calculating electromagnetic scattering characteristics of super-electric large-size structure - Google Patents

Method and device for calculating electromagnetic scattering characteristics of super-electric large-size structure Download PDF

Info

Publication number
CN117350083B
CN117350083B CN202311640083.6A CN202311640083A CN117350083B CN 117350083 B CN117350083 B CN 117350083B CN 202311640083 A CN202311640083 A CN 202311640083A CN 117350083 B CN117350083 B CN 117350083B
Authority
CN
China
Prior art keywords
bounding box
node
ray
incident
wave
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202311640083.6A
Other languages
Chinese (zh)
Other versions
CN117350083A (en
Inventor
谢志祥
周洪伟
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shenzhen Shifeng Technology Co ltd
Original Assignee
Shenzhen Shifeng Technology Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shenzhen Shifeng Technology Co ltd filed Critical Shenzhen Shifeng Technology Co ltd
Priority to CN202311640083.6A priority Critical patent/CN117350083B/en
Publication of CN117350083A publication Critical patent/CN117350083A/en
Application granted granted Critical
Publication of CN117350083B publication Critical patent/CN117350083B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Evolutionary Computation (AREA)
  • Geometry (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Management, Administration, Business Operations System, And Electronic Commerce (AREA)
  • Image Generation (AREA)

Abstract

The application relates to the field of electromagnetic simulation of super-electric large-size structures, in particular to a method and a device for calculating electromagnetic scattering characteristics of the super-electric large-size structures, wherein the method comprises the following steps: updating the cue pointers of all the node bounding box surfaces according to the relative position relation between all the node bounding box surfaces in the KD-Tree binary Tree of the target model of the super-electric large-size structure and the node bounding box segmentation surface pointed by the cue pointers; and determining an incident electric field of the triangular surface element illuminated by the incident wave and a reflected electric field and a reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave based on the cue pointers of the surfaces of the updated node bounding box, and calculating the electromagnetic scattering characteristics of the super-large-size structure. The surface area heuristic strategy is adopted, the vertex and the segmentation idea of the face element are combined, the three-dimensional KD-Tree binary Tree structure of the target model is built, the construction time of the KD-Tree binary Tree is greatly shortened, and the calculation efficiency is improved.

Description

Method and device for calculating electromagnetic scattering characteristics of super-electric large-size structure
Technical Field
The invention relates to the field of electromagnetic simulation of super-electric large-size structures, in particular to a method and a device for calculating electromagnetic scattering characteristics of super-electric large-size structures.
Background
The electromagnetic simulation technology is used for obtaining the scattering property of the super-electric large-size structure, which is an important way for reducing the actual measurement cost of a real object, in order to reduce the scattering intensity of the super-electric large-size structure, a layer of wave absorbing material is coated on the surface of a target model of the super-electric large-size structure, a layer of isotropic medium is coated on the outer surface of the super-electric large-size structure by the traditional coating method, and the electromagnetic property of the surface of the super-electric large-size structure can be obtained by the ray tracing technology no matter the coating thickness is, but the wave absorbing property is far different from that of the coating of anisotropic medium.
However, when a thin anisotropic medium is coated on the surface of the super-electric large-size structure, and the wavelength of electromagnetic waves is in a millimeter wave band or below, a large amount of memory and calculation time are consumed in a huge subdivision number and a complicated ray tracing process, so that the traditional technical means cannot perform high-efficiency numerical simulation at all, the calculation accuracy of the whole target model is reduced, and the calculation efficiency of the electromagnetic scattering characteristics of the super-electric large-size structure is further reduced.
Disclosure of Invention
In view of the above, an object of the present application is to provide a method and apparatus for calculating electromagnetic scattering characteristics of an oversized structure, which can calculate electromagnetic scattering characteristics of an oversized structure having an electrical size of more than 300 wavelengths and an anisotropic medium having an outer surface coated with a thickness of less than one wavelength, thereby shortening the time for calculating electromagnetic scattering characteristics of the oversized structure and improving the efficiency of calculating electromagnetic scattering characteristics of the oversized structure.
In a first aspect, an embodiment of the present application provides a method for calculating electromagnetic scattering characteristics of an oversized structure, where the method for calculating electromagnetic scattering characteristics of the oversized structure includes:
constructing a target model of the super-electric large-size structure, and extracting coordinate information of each triangular surface element and a surface element normal vector in the target model; the electrical dimension of the super-electrical large-size structure is larger than 300 wavelengths, and the outer surface of the super-electrical large-size structure is coated with an anisotropic medium with the thickness smaller than one wavelength;
constructing a KD-Tree binary Tree for the target model according to the coordinate information of all the triangular surface elements; in the constructed KD-Tree Tree structure, each node bounding box consists of 6 faces, and each face corresponds to a clue pointer; the cue pointer of each face points to a node bounding box adjacent to the respective face;
Updating the cue pointers of the faces of each node bounding box according to the relative position relation between the 6 faces of each node bounding box and the partitioned faces of the node bounding box pointed by the corresponding cue pointers;
determining an incident electric field corresponding to the triangular surface element directly illuminated by the incident wave of the electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave in all the triangular surface elements according to the surface element normal vector, the constructed KD-Tree and the updated clue pointers of each surface of each node bounding box; electromagnetic waves are in the millimeter or lower wave band;
the electromagnetic scattering characteristics of the oversized structure are calculated from the incident electric field corresponding to the triangular cells directly illuminated by the incident wave of the electromagnetic wave, and the reflected electric field and the reflected magnetic field of the triangular cells illuminated by the reflected ray of the incident wave.
In one possible implementation manner, the construction of the KD-Tree binary Tree for the target model according to the coordinate information of all the triangular surface elements comprises the following steps:
constructing an axis alignment bounding box containing all triangular surface elements according to the coordinate information of all triangular surface elements to obtain a bounding box corresponding to the root node;
determining a segmentation surface of the bounding box corresponding to the root node according to the number of triangle surface elements in the bounding box corresponding to the root node, the number of vertexes and the projection length of the bounding box corresponding to the root node on each coordinate axis;
Dividing the root node bounding box by dividing the bounding box corresponding to the root node to obtain left and right child node bounding boxes corresponding to the root node; the face information in the bounding box corresponding to the root node is pressed into the bounding boxes corresponding to the left child node and the right child node; recursion left and right child node bounding boxes, and exiting when reaching a termination condition;
aiming at each node bounding box in the currently constructed KD-Tree; judging whether the node bounding box meets a termination condition or not; wherein the termination condition includes: i. the number of triangular surface elements in the node bounding box is smaller than the preset number; ii. The depth corresponding to the node bounding box is larger than a preset depth threshold; iii, the cost of the surface area heuristic SAH corresponding to the node bounding box when the node bounding box is not segmented is lower than the cost of the SAH corresponding to the segmented node bounding box; iv, the distance between the dividing plane corresponding to the divided node bounding box and the six faces of the node bounding box is smaller than the preset distance;
if the node bounding box does not meet the termination condition, determining a segmentation surface of the node bounding box according to the number of triangular surface elements in the node bounding box, the number of vertexes and the projection length of the triangle surface elements on each coordinate axis, and continuing segmentation; otherwise, the node bounding box is defined as a leaf node or a null node bounding box, segmentation is stopped, and the bin information within the leaf node is pressed into the bounding box.
In one possible embodiment, the segmentation plane of the node bounding box is determined by:
determining a coordinate point corresponding to one half of the projection length of the node bounding box on each coordinate axis as a first search boundary of the optimal segmentation plane;
determining a second search boundary of the optimal segmentation surface according to one half of the number of vertexes of the triangular surface element in the node bounding box;
determining the first search boundary and the second search boundary as boundaries of search intervals of the optimal segmentation surface;
traversing three axes of X, Y and Z, calculating SAH costs of all surface area heuristic strategies in the search interval, and determining a segmentation plane with the minimum SAH costs as an optimal segmentation plane.
In one possible implementation, updating the cue pointers of the respective faces of the bounding boxes of nodes according to the relative positional relationship between the 6 faces of the bounding boxes of nodes and the partitioned faces of the bounding boxes of nodes pointed to by the corresponding cue pointers, includes:
creating a null line pointer for the root node bounding box, taking the null line pointer as input, and inheriting the cue pointer of the father node to the left child node and the right child node; according to plane information of the internal division surfaces of each father node bounding box, a right cue pointer of a left child node is pointed to the right child node, and a left cue pointer of the right child node is pointed to the left child node so as to complete a cue process and obtain cue pointers of each surface of each node bounding box;
Judging whether the section is parallel to the dividing surface of the node bounding box pointed by the corresponding cue pointer aiming at each surface of the node bounding box;
if the surface is parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer, pointing the corresponding cue pointer to the left sub-node corresponding node bounding box or the right sub-node corresponding node bounding box of the node bounding box pointed by the corresponding cue pointer;
if the surface is not parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer and the coordinate of the partition surface of the node bounding box pointed by the corresponding cue pointer is larger than the coordinate of the node bounding box where the surface is located, the right child node of the node bounding box pointed by the corresponding cue pointer is pointed by the corresponding cue pointer;
if the surface is not parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer and the coordinate of the partition surface of the node bounding box pointed by the corresponding cue pointer is smaller than the coordinate of the node bounding box where the surface is located, the corresponding cue pointer is pointed to the node bounding box corresponding to the left child node of the node bounding box pointed by the corresponding cue pointer, so that the optimization of the cue pointer is completed.
In one possible implementation, determining, from the bin normal vector, the constructed KD-Tree, and the updated cue pointers for each face of each node bounding box, an incident electric field corresponding to a triangular bin directly illuminated by an incident wave of the electromagnetic wave, and a reflected electric field and a reflected magnetic field of a triangular bin illuminated by a reflected ray of the incident wave, among all triangular bins, includes:
if the distance between the emitting source of the incident wave and the target model is greater than the preset distance, the incident wave is taken as a plane wave, and the pitch angle of the plane wave incident to the center of the triangular surface element is determinedθAnd azimuth angleφCalculating the incident wave vector；
If the distance between the emitting source of the incident wave and the target model is smaller than the preset distance, the incident wave is taken as a spherical wave according to the emitting source of the incident wave orThe electric field and the magnetic field on a certain sealing surface of the surrounding emitting source are used for calculating the incident wave vector；
According to the incident wave vectorThe normal vector of the surface element, the constructed KD-Tree and the updated clue pointers of 6 surfaces of each node bounding box determine the incident electric field corresponding to the triangular surface element directly illuminated by the incident wave of the electromagnetic wave, and the reflected electric field and the reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave.
In one possible embodiment, the vector of the incident waveDetermining an incident electric field corresponding to a triangular surface element directly illuminated by an incident wave of an electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular surface element illuminated by a reflected ray of the incident wave, wherein the method comprises the following steps of:
judging the incident wave vector incident on the center of each triangular surface elementVector normal to the triangle bin>Whether or not to satisfy->·<0.00; if not, determining the triangular surface element as an occluded surface element and discarding the occluded surface element;
if so, taking the center of the triangle surface element as the ray starting point, taking-For the propagation direction of ray tracing, rays are according to the characteristic that light propagates along a straight line>Tracking and ray->Determining as a first ray; if the first ray does not intersect any triangular surface element in all node bounding boxes of the constructed KD-tree, the triangular surface element is considered to be the triangular surface element illuminated by the incident wave, and an incident electric field corresponding to the triangular surface element illuminated by the incident wave is obtained; otherwise, the triangular surface element is considered as the shielded surface element and is discarded;
Following the law of reflection in geometrical optics, at the wave being incidentGenerating a corresponding reflected ray in the illuminated triangular surface element; determining the reflected ray as a second ray, using the center of the illuminated triangular surface element as a starting point of the second ray, and tracking the second ray to obtain all the triangular surface elements illuminated by the second ray, and a reflected electric field and a reflected magnetic field of the triangular surface elements illuminated by the second ray;
if the tracking times are smaller than the preset times and the second ray intersects the target model, the second ray is used as a new incident waveAnd jumps to follow the law of reflection in geometrical optics, at the incident wave +.>A corresponding reflected ray is generated in the illuminated triangular bin to continue execution.
In one possible implementation, the incident wave vector incident on the triangle bin center is calculatedAn incident electric field of triangular cells illuminated by an incident wave, comprising:
if the type of the incident wave is plane wave, substituting the pitch angle and the azimuth angle of the incident wave into the following formula to calculate the vector of the incident wave incident to the triangle surface element centerAn incident electric field of a triangular cell illuminated by the incident wave;
；
if the VV polarization is used as the calculation condition:
Then the first time period of the first time period,；
if HH polarization is used as the calculation condition:
then the first time period of the first time period,；
wherein,is the incident wave vector of the triangular surface element, +.>For the incident electric field at the center of the triangle surface element when the incident wave is of the plane wave type, +.>For pitch angle of incident wave, +.>For azimuth angle of incident wave, +.>Is the basic unit of imaginary number, +.>Wave number of electromagnetic wave, < >>Is three in threeA corner-element center position vector;
if the type of the incident wave is spherical wave, substituting the electric field and the magnetic field on the emission source of the electromagnetic wave or a certain sealing surface surrounding the emission source into the following formula to calculate the incident wave vector incident to the center of the triangular surface element；
；
；
If the type of the incident wave is a plane wave, the pitch angle and the azimuth angle of the incident wave are substituted into the following formula,，；
；；；
wherein,is an electromagnetic wave emission source or an incident electric field surrounding any point outside the sealing surface of the emission source,is the electromagnetic wave emission source or the incident magnetic field surrounding any point outside the emission source sealing surface, +.>Is the emission source of electromagnetic wave or the position vector surrounding any point outside the sealing surface of the emission source,jis the basic unit of imaginary number, +.>For the angular frequency of the incident wave, +.> 0 Is magnetic permeability in free space, < >>For the radiation source or for the area of a certain sealing surface surrounding the radiation source, +. >Representing the distance from the source point to the viewpoint, +.>For equivalent current vectors on the emission source or surrounding emission source closure surface +.>Equivalent magnetic current vector epsilon on the sealing surface of the emission source or the surrounding emission source respectively 0 Is the dielectric constant in free space, +.>Is a vector of the face normal>For the electric field vector on the emitter or surrounding emitter envelope, +.>For the magnetic field vector on the emission source or surrounding emission source closure surface, +.>A position scalar for an electromagnetic wave emission source or surrounding any point on an emission source sealing surface;
triangular surface element to be illuminated by incident waveAn incident electric field is determined as a triangular bin illuminated by the incident wave.
In one possible implementation, tracking the first ray or the second ray includes:
judging whether the starting point coordinates of the rays are inside the current tracking bounding box or not; the ray is a first ray or a second ray;
if the starting point coordinates of the ray are inside the current tracking bounding box, determining a bounding box of a leaf node closest to the current tracking bounding box on the ray; judging whether the ray intersects with a triangle surface element in a bounding box of the leaf node or not; if the ray intersects a certain triangular surface element in the bounding box of the leaf node, determining and recording the triangular surface element intersected with the ray as the triangular surface element hit by the ray; and stopping tracking;
If the ray does not intersect all the triangular surface elements in the bounding box of the leaf node, determining the triangular surface elements directly illuminated by the ray according to the cue pointers of the surfaces of the bounding box of the leaf node;
if the starting point coordinates of the ray are not inside the current tracking bounding box, determining a bounding box of a leaf node closest to the current tracking bounding box on the ray; judging whether the ray hits the bounding box of the leaf node or not; if the ray hits the bounding box of the leaf node, jumping to judge whether the ray intersects with the triangle surface element in the bounding box of the leaf node or not so as to continue execution; if the ray does not hit the bounding box of the leaf node, judging whether the ray hits the external nested triangle surface element of the bounding box of the leaf node;
and determining the triangle surface element hit by the ray from all the external nested triangle surface elements according to the judging result.
In one possible implementation, determining a bounding box of a leaf node on the ray closest to the current tracking bounding box includes:
judging whether the current tracking bounding box is a leaf node bounding box or not; if the current tracking bounding box is not the bounding box of the leaf node, determining a bounding box of the leaf node closest to the current tracking bounding box on the ray through a recursion algorithm; if the current tracking bounding box is a bounding box of the leaf node, taking the current tracking bounding box as a nearest bounding box of the leaf node;
Determining a triangle primitive directly illuminated by the ray from the cue pointers of the faces of the bounding box of the leaf node, comprising:
determining the planes of the bounding box of the leaf node, through which rays pass, from the planes of the bounding box of the leaf node; judging whether the bounding box pointed by the clue pointer of the surface of the bounding box of the ray passing out of the leaf node is the bounding box of the root node or not; if the bounding box pointed by the cue pointer of the surface of the bounding box of the ray passing out of the leaf node is the bounding box of the root node, when the ray is the first ray, the triangle surface element where the ray starting point is positioned is the triangle surface element directly illuminated by the ray; stopping tracking when the ray is the second ray; if the bounding box pointed by the thread pointer of the ray passing out of the face of the bounding box of the leaf node is not the bounding box of the root node, updating the bounding box pointed by the thread pointer of the ray passing out of the face of the bounding box of the leaf node into the current tracking bounding box of the ray, and jumping to judge whether the starting point coordinate of the ray is inside the current tracking bounding box or not so as to continue execution.
In one possible implementation, determining a triangle that is hit by the ray from all externally nested triangle elements according to the determination result includes:
If the judgment result is that the ray hits the external nested triangular surface element of the bounding box of the leaf node, determining and recording the external nested triangular surface element which is hit as the triangular surface element which is hit by the ray;
if the ray misses an external nested triangle of the bounding box of the leaf node, then the triangle directly illuminated by the ray is determined from the thread pointer of the face of the bounding box of the leaf node.
In one possible embodiment, calculating electromagnetic scattering characteristics of an oversized structure from an incident electric field corresponding to a triangular cell directly illuminated by an incident wave of an electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular cell illuminated by a reflected ray of the incident wave, includes:
calculating electromagnetic scattering characteristics of the super-electric large-size structure by the following formula, wherein the electromagnetic scattering characteristics comprise a total scattering field of the super-electric large-size structure in a far field area and RCS of the super-electric large-size structure;
；
；
；
wherein,PO solution of triangular surface element directly illuminated by incident wave of electromagnetic wave or illuminated by reflected ray corresponding to incident wave, ++>For plane wave pitch angle incident to the surface of super-electric large-size structure, < >>For plane wave azimuth angle incident to the surface of super-electric large-sized structure, < - >Is imaginary number and is->Wave number of electromagnetic wave, < >>For far field distance>Is the unit vector of far field point, +.>Is electromagneticWave emission source or position scalar surrounding any point on the emission source closing surface, +.>For the integral area of a single triangular bin, +.>Is a vector of the face normal>Is magnetic permeability in free space, < >>Is the dielectric constant in free space, +.>An incident electric field directly illuminated by an incident wave of an electromagnetic wave, and a sum of the reflected electric fields of triangular elements illuminated by reflected rays of said incident wave, +.>For the sum of an incident magnetic field directly illuminated by an incident wave of an electromagnetic wave and a reflected magnetic field of a triangular surface element illuminated by a reflected ray of said incident wave, +.>For the total scattering field of the entire super-electrically large-sized structure in the far-field region, +.>For the number of triangular elements directly illuminated by the initial incident wave of the electromagnetic wave, +.>PO solution for the ith triangle element directly illuminated by the initial incident wave of electromagnetic wave, T is the number of ray tracing, +.>Tracking for the nth ray the PO solutions of all triangular elements illuminated by the reflected rays of said incident wave,/->RCS, which is an oversized structure, in dB/sm,when the type of the incident wave is plane wave, the triangle surface element illuminated by the incident wave of electromagnetic wave and the reflected ray of the incident wave >Is the radar cross section of the oversized structure.
In a second aspect, embodiments of the present application further provide a device for calculating electromagnetic scattering properties of an oversized structure, the device including:
the extraction module is used for constructing a target model of the super-electric large-size structure and extracting coordinate information and a surface element normal vector of each triangular surface element in the target model; the electrical dimension of the super-electrical large-size structure is larger than 300 wavelengths, and the outer surface of the super-electrical large-size structure is coated with an anisotropic medium with the thickness smaller than one wavelength;
the construction module is used for constructing a KD-Tree binary Tree for the target model according to the coordinate information of all the triangular surface elements; in the constructed KD-Tree Tree structure, each node bounding box consists of 6 faces, and each face corresponds to a clue pointer; the cue pointer of each face points to a node bounding box adjacent to the respective face;
the updating module is used for updating the cue pointers of the faces of each node bounding box according to the relative position relation between the 6 faces of each node bounding box and the partition faces of the node bounding box pointed by the corresponding cue pointers;
The determining module is used for determining an incident electric field corresponding to the triangular surface element directly illuminated by the incident wave of the electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave in all the triangular surface elements according to the normal vector of the surface element, the constructed KD-Tree and the updated clue pointers of each surface of each node bounding box; the electromagnetic wave is in a wave band below millimeter;
and the calculation module is used for calculating the electromagnetic scattering property of the super-electric large-size structure according to the incident electric field corresponding to the triangular surface element directly illuminated by the incident wave of the electromagnetic wave, and the reflected electric field and the reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave.
In a third aspect, an embodiment of the present application further provides an electronic device, including: the system comprises a processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor communicates with the storage medium through the bus, and the processor executes the machine-readable instructions to execute the steps of the method for calculating the electromagnetic scattering characteristics of the super-electric large size structure according to any one of the first aspect.
In a fourth aspect, embodiments of the present application further provide a computer readable storage medium having a computer program stored thereon, the computer program when executed by a processor performing the steps of the method for calculating electromagnetic scattering properties of an oversized structure as in any of the first aspects.
The embodiment of the application provides a method and a device for calculating electromagnetic scattering characteristics of an ultra-electric large-size structure, wherein the method comprises the following steps: updating the cue pointers of the faces of the node bounding boxes according to the relative position relationship between the 6 faces of the corresponding node bounding boxes in the KD-Tree binary Tree corresponding to the target model of the super-electric large-size structure and the segmentation faces of the node bounding boxes pointed by the corresponding cue pointers; the electromagnetic scattering characteristics of the oversized structure are calculated based on the updated incident electric field of the triangular surface element directly illuminated by the incident wave of the electromagnetic wave and the reflected electric field and the reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave, which are determined by the cue pointers of the surfaces of the node bounding boxes, so that the time for calculating the electromagnetic scattering characteristics of the oversized structure with the electric size larger than 300 wavelengths and the anisotropic medium with the thickness smaller than one wavelength coated on the outer surface is shortened, and the efficiency for calculating the electromagnetic scattering characteristics of the oversized structure is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic flow chart of a method for estimating electromagnetic scattering characteristics of an anisotropic medium coated target according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a scenario in which thread pointers on faces of bounding boxes are updated according to an embodiment of the present application;
FIG. 3 is a schematic diagram of another scenario for updating thread pointers on faces of bounding boxes according to an embodiment of the present application;
FIG. 4 is a schematic view of a scene of incident waves that are irradiated to a target model and reflected according to an embodiment of the present application;
FIG. 5 shows a flowchart for tracking a ray according to an embodiment of the present application;
fig. 6 is a schematic diagram of a coordinate system of an incident plane when an incident wave provided in an embodiment of the present application is a plane wave;
FIG. 7 illustrates a schematic diagram of an exemplary infinite PEC planar overcoated anisotropic dielectric layer model provided in accordance with an embodiment of the present application;
FIG. 8 illustrates a computing device for electromagnetic scattering properties of an oversized structure provided in an embodiment of the present application;
fig. 9 shows a schematic structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, which are generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, as provided in the accompanying drawings, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. Based on the embodiments of the present application, every other embodiment that a person skilled in the art would obtain without making any inventive effort is within the scope of protection of the present application.
In order to enable those skilled in the art to use the present application, in connection with a specific application scenario "electromagnetic simulation field of ultra-large-sized structures", the following embodiments are presented. It will be apparent to those having ordinary skill in the art that the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present application. Although the present application is described primarily in the context of "electromagnetic simulation of oversized structures," it should be understood that this is but one exemplary embodiment.
It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the presence of the features stated hereinafter, but not to exclude the addition of other features.
The following describes in detail a method for calculating electromagnetic scattering characteristics of an oversized structure provided in the embodiment of the present application.
Referring to fig. 1, a flow chart of a method for calculating electromagnetic scattering characteristics of an oversized structure according to an embodiment of the present application is shown, and the following description describes exemplary steps of the embodiment of the present application:
s101, constructing a target model of the super-electric large-size structure, and extracting coordinate information and a normal vector of each triangular surface element in the target model.
In an embodiment of the present application, the electrical dimension of the oversized structure is greater than 300 wavelengths, and the outer surface of the oversized structure is coated with an anisotropic medium having a thickness less than one wavelength; modeling the super-electric large-size structure with the electric large size by adopting a 3D modeling mode based on a triangular surface element grid, and deriving a model file with a general 3D model file format STL (Stereo Lithography) or STEP and other formats to obtain a target model of the super-electric large-size structure. The model file in the format of STL/STEP is imported into Gmesh mesh division software to read coordinate information and a vector normal for each triangular element of the super-electric large-size structure constituting the radar target.
S102, constructing a KD-Tree binary Tree for the target model according to the coordinate information of all the triangular surface elements.
In the embodiment of the application, a surface area heuristic SAH is set to construct a KD-Tree binary Tree for the target model. Each node in the constructed KD-Tree corresponds to a bounding box, which is also called a node bounding box, and each node bounding box contains 0 or more triangular surface elements; the node bounding box is a regular rectangular cuboid. In the constructed KD-Tree Tree structure, each node bounding box consists of 6 faces, and each face corresponds to a clue pointer; the cue pointer for each facet points to the bounding box of nodes adjacent to the facet.
Constructing a KD-Tree binary Tree for the target model by the following steps:
constructing an axis alignment bounding box containing all triangular surface elements according to the coordinate information of all triangular surface elements, and obtaining a bounding box corresponding to the root node.
In the embodiment of the application, the minimum coordinate value and the maximum coordinate value on the X axis, the minimum coordinate value and the maximum coordinate value on the Y axis, and the minimum coordinate value and the maximum coordinate value on the Z axis are found out from the coordinate information of all the triangular surface elements, a minimum axis alignment bounding box capable of containing all the triangular surface elements is constructed through the six coordinate values, and the bounding box is used as a bounding box corresponding to a root node in the KD-Tree.
And step two, determining the segmentation surface of the bounding box corresponding to the root node according to the number of triangle surface elements in the bounding box corresponding to the root node, the number of vertexes and the projection length of the bounding box corresponding to the root node on each coordinate axis.
Dividing the root node bounding box through the division of the bounding box corresponding to the root node to obtain left and right child node bounding boxes corresponding to the root node; the face information in the bounding box corresponding to the root node is pressed into the bounding boxes corresponding to the left child node and the right child node; and recursively, the left child node bounding box and the right child node bounding box exit when the termination condition is reached.
In this embodiment of the present application, generally, a bounding box corresponding to a smaller-coordinate child node of the bounding boxes corresponding to the two segmented child nodes is taken as a bounding box corresponding to the left child node, and a bounding box corresponding to a larger-coordinate child node is taken as a bounding box corresponding to the right child node, and such a strategy is adopted in the following scheme description. However, the present application is not limited to the case of using the large coordinates as the left child node or the right child node, and depends on the actual situation.
Step four, aiming at each node bounding box in the currently constructed KD-Tree; and judging whether the node bounding box meets the termination condition.
Wherein the termination condition includes: i. the number of triangular surface elements in the node bounding box is smaller than the preset number; ii. The depth corresponding to the node bounding box is larger than a preset depth threshold; iii, the cost of the surface area heuristic SAH corresponding to the node bounding box when the node bounding box is not segmented is lower than the cost of the SAH corresponding to the segmented node bounding box; iv, the distance between the dividing plane corresponding to the divided node bounding box and the six faces of the node bounding box is smaller than the preset distance;
here, the preset number is typically between 32-50, and the preset depth threshold is calculated by the following formula:
The method comprises the steps of carrying out a first treatment on the surface of the Wherein (1)>For a preset depth threshold->Is the total number of triangular surface elements in the target model.
Step five, if the node bounding box does not meet the termination condition, determining a segmentation surface of the node bounding box according to the number of triangular surface elements in the node bounding box, the number of vertexes and the projection length on each coordinate axis, and continuing segmentation; otherwise, the node bounding box is defined as a leaf node or a null node bounding box, segmentation is stopped, and the bin information within the leaf node is pressed into the bounding box.
Further, the split plane of the node bounding box is determined by:
I. and determining a coordinate point corresponding to one half of the projection length of the node bounding box on each coordinate axis as a first search boundary of the optimal segmentation plane.
In the embodiment of the application, one half of the projection length of the node bounding box on the X coordinate axis is taken as a first search boundary of the node bounding box on the optimal division plane of the X coordinate axis, one half of the projection length of the node bounding box on the Y coordinate axis is taken as a first search boundary of the node bounding box on the optimal division plane of the Y coordinate axis, and one half of the projection length of the node bounding box on the Z coordinate axis is taken as a first search boundary of the node bounding box on the optimal division plane of the Z coordinate axis.
Taking an example of an X coordinate axis, if the projection length of the node bounding box on the X coordinate axis is L, the first search boundary of the node bounding box on the optimal partition plane of the X coordinate axis is L/2.
II. A second search boundary of the optimal segmentation surface is determined based on one-half of the number of vertices of the triangular primitives within the bounding box of nodes.
In the embodiment of the application, according to a function of the projection of the number of the vertexes on the left side of the partition plane along with the X-axis coordinate, determining a second search boundary of the node bounding box on the optimal partition plane of the X-axis coordinate; determining a second search boundary of the node bounding box on the optimal partition surface of the Y coordinate axis according to a function of one half of the number of the vertices of the triangular surface elements in the node bounding box and the projection of the number of the vertices on the left side of the partition surface along with the Y coordinate axis; and determining a second search boundary of the optimal segmentation surface of the node bounding box on the Z coordinate axis according to a function of the projection of the number of the vertices on the left side of the segmentation surface along with the Z coordinate according to one half of the number of the vertices of the triangular surface elements in the node bounding box.
Taking the X axis as an example, according to N L (p) =nx/2, determining a second search boundary of the optimal division plane, where N L For the function of the projection of the number of vertexes on the left side of the segmentation plane along with the X-axis coordinate, p is the second search boundary of the optimal segmentation plane, and Nx node surrounds the number of triangle surface element vertexes in the box.
III, determining the first search boundary and the second search boundary as boundaries of the search interval of the optimal segmentation plane.
In the embodiment of the application, a first search boundary and a second search boundary corresponding to an X axis are determined as boundaries of search intervals of an optimal division plane corresponding to the X axis; determining a first search boundary and a second search boundary corresponding to the Y axis as boundaries of search intervals of the optimal segmentation planes corresponding to the Y axis; and determining the first search boundary and the second search boundary corresponding to the Z axis as boundaries of search intervals of the optimal segmentation planes corresponding to the Z axis.
IV, traversing three axes of X, Y and Z, calculating SAH costs of all surface area heuristic strategies in the search interval, and determining a segmentation plane with the minimum SAH costs as an optimal segmentation plane.
In the embodiment of the application, a partition surface with the minimum surface area heuristic SAH cost in a search interval of the optimal partition surface of the X coordinate axis is determined as a first partition surface; determining a partition surface with the minimum surface area heuristic SAH cost in a search interval of the optimal partition surface of the Y coordinate axis as a second partition surface; determining a segmentation surface with the minimum cost of the surface area heuristic SAH of the search interval of the optimal segmentation surface in the Z coordinate axis as a third segmentation surface; and determining the segmentation surface with the minimum cost of the surface area heuristic strategy SAH of the first segmentation surface, the second segmentation surface and the third segmentation surface as the segmentation surface corresponding to the bounding box.
S103, updating the cue pointers of the surfaces of each node bounding box according to the relative position relation between the 6 surfaces of each node bounding box and the partitioned surfaces of the node bounding box pointed by the corresponding cue pointers
In the embodiment of the application, the node bounding box pointed by the cue pointer on each surface of each updated node bounding box is the nearest node bounding box in all the node bounding boxes, so that the follow-up time for tracking the ray can be shortened, and the acquisition efficiency of the electromagnetic scattering characteristic is improved.
Updating thread pointers for each face of each node bounding box by:
I. creating a null line pointer for the root node bounding box, taking the null line pointer as input, and inheriting the cue pointer of the father node to the left child node and the right child node; according to plane information of the internal division surfaces of each father node bounding box, a right cue pointer of a left child node is pointed to the right child node, and a left cue pointer of the right child node is pointed to the left child node so as to complete a cue process and obtain cue pointers of each surface of each node bounding box;
specifically, starting from the root bounding box, since each node bounding box includes 6 planes, the null line pointer of the root bounding box is actually a set of integer arrays [ -1, -2, -3, -4, -5, -6] for the 6 planes, and the line pointer array information is constant. After the root bounding box is partitioned, if the index of the left child bounding box is index_l, the index of the right child bounding box is index_r. If the partition plane of the root node bounding box is perpendicular to the X axis, the updated left child node bounding box clue pointer information is [ -1, index_R, -3, -4, -5, -6], and the updated right child node bounding box clue pointer information is [ index_L, -2, -3, -4, -5, -6]; similarly, if the partition plane is perpendicular to the Y axis, the updated left child node bounding box cue pointer information is [ -1, -2, -3, index_R, -5, -6], and the updated right child node bounding box cue pointer information is [ -1, -2, index_L, -4, -5, -6]; if the partition plane is perpendicular to the Z axis, the updated cue pointer information of the left child node bounding box is [ -1, -2, -3, -4, -5, index_R ], and the updated cue pointer information of the right child node bounding box is [ -1, -2, -3, -4, index_L, -6]. Similarly, the clue information of the left and right child node bounding boxes is recursively recovered, and when the parent node bounding box is a leaf node or a null node, the clue information is stopped and exited.
II. For each surface of each bounding box, judging whether the section is parallel to the segmentation surface of the bounding box pointed by the corresponding cue pointer.
And III, if the surface is parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer, pointing the corresponding cue pointer to the left sub-node corresponding node bounding box or the right sub-node corresponding node bounding box of the node bounding box pointed by the corresponding cue pointer.
FIG. 2 is a schematic view of a scene for updating cue pointers on each surface of bounding boxes according to an embodiment of the present application; the thread pointer of the surface 1 in the bounding box 1 points to the bounding box 2, the bounding box 2 is divided into a bounding box a1 corresponding to the left child node and a bounding box a2 corresponding to the right child node by dividing the surface p1, and the surface 1 in the bounding box 1 is parallel to the dividing surface p1, so that the thread pointer corresponding to the surface 1 points to the bounding box a1 or the bounding box a2.
And IV, if the surface is not parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer and the coordinate of the partition surface of the node bounding box pointed by the corresponding cue pointer is larger than the coordinate of the node bounding box where the surface is located, the right child node of the node bounding box pointed by the corresponding cue pointer is pointed by the corresponding cue pointer.
FIG. 3 is a schematic view of another scenario for updating thread pointers on each surface of bounding boxes according to an embodiment of the present disclosure; the thread pointer of the surface 2 in the bounding box 3 points to the bounding box 4, the bounding box 4 is divided into a bounding box b1 corresponding to the left child node and a bounding box b2 corresponding to the right child node by dividing the surface p2, the surface 2 in the bounding box 3 is not parallel to the dividing surface p2, and the coordinates of the dividing surface of the bounding box to which the thread pointer corresponding to the surface 2 points are larger than the coordinates of the bounding box to which the surface is located, so the thread pointer corresponding to the surface 2 points to the bounding box b2.
And V, if the surface is not parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer and the coordinate of the partition surface of the node bounding box pointed by the corresponding cue pointer is smaller than the coordinate of the node bounding box where the surface is located, the corresponding cue pointer is pointed to the node bounding box corresponding to the left child node of the node bounding box pointed by the corresponding cue pointer, so that the optimization of the cue pointer is completed.
S104, determining an incident electric field corresponding to the triangular surface element directly illuminated by the incident wave of the electromagnetic wave and a reflected electric field and a reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave in all the triangular surface elements according to the normal vector of the surface element, the constructed KD-Tree and the updated clue pointers of each surface of each node bounding box.
Wherein the electromagnetic wave is in a wave band of millimeter or below; the emission source of electromagnetic wave can be antenna on large carrier platform, radar at infinity, etc., and the specific emission source is not limited. As shown in fig. 4, a schematic view of a scene in which an incident wave provided in an embodiment of the present application irradiates a target model and reflects.
Specifically, an incident electric field corresponding to a triangular cell directly illuminated by an incident wave of an electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular cell illuminated by a reflected ray of the incident wave are determined by:
I. if the distance between the emitting source of the incident wave and the target model is greater than the preset distance, the incident wave is taken as a plane wave, and the pitch angle of the plane wave incident to the center of the triangular surface element is determinedθAnd azimuth angleφCalculating the incident wave vector；
II. If the distance between the emitting source of the incident wave and the target model is smaller than the preset distance, the incident wave is taken as a spherical wave, and the vector of the incident wave is calculated according to the electric field and the magnetic field on the emitting source of the incident wave or a sealing surface surrounding the emitting source；
III, according to the incident wave vectorDetermining the normal vector of the surface element, the constructed KD-Tree and the updated clue pointers of 6 surfaces of each node bounding box An incident electric field corresponding to a triangular cell directly illuminated by an incident wave of an electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular cell illuminated by a reflected ray of the incident wave.
Determining an incident electric field corresponding to a triangular cell directly illuminated by an incident wave of an electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular cell illuminated by a reflected ray of the incident wave by:
i. judging the incident wave vector incident on the center of each triangular surface elementVector normal to the triangle bin>Whether or not to satisfy->·<0.00; if not, the triangle bin is determined to be an occluded bin and discarded.
ii. If so, taking the center of the triangle surface element as the ray starting point, taking-For the propagation direction of ray tracing, rays are according to the characteristic that light propagates along a straight line>Tracking and ray->Determining as a first ray; if the first ray does not intersect any triangular surface element in all node bounding boxes of the constructed KD-tree, the triangular surface element is considered to be the triangular surface element illuminated by the incident wave, and an incident electric field corresponding to the triangular surface element illuminated by the incident wave is obtained; otherwise, the triangle is considered as the blocked surface element and is discarded.
In the embodiment of the present application, the first ray is tracked here, which can also be understood as a back-tracking of the incident wave.
iii, following the law of reflection in geometrical optics, at the wave being incidentGenerating a corresponding reflected ray in the illuminated triangular surface element; and determining the reflected ray as a second ray, tracking the second ray by taking the center of the illuminated triangular surface element as the starting point of the second ray, and obtaining all the triangular surface elements illuminated by the second ray, and the reflected electric field and the reflected magnetic field of the triangular surface elements illuminated by the second ray.
In this embodiment, after the incident wave is reflected or transmitted, the reflected and/or transmitted second ray is tracked as a new ray.
Here, the law of reflection is:；
the law of transmission is:；k 1 is the propagation constant, k, of the space in which the incident wave is located 2 Is a constant of the space in which the refracted wave is located, +.>，。
Wherein,for the reflected ray unit vector, < >>Is a transmitted wave unit vector.
iv, if the tracking frequency is smaller than the preset frequency and the second ray intersects the target model, taking the second ray as a new incident waveAnd jumps to follow the law of reflection in geometrical optics, at the incident wave +. >A corresponding reflected ray is generated in the illuminated triangular bin to continue execution.
Further, an incident wave vector incident on the triangle cell center is calculated by the steps ofAn incident electric field of triangular cells illuminated by an incident wave, comprising:
step one, if the type of the incident wave is plane wave, substituting the pitch angle and the azimuth angle of the incident wave into the following formula to calculate the vector of the incident wave incident to the triangle surface element centerAn incident electric field of a triangular cell illuminated by the incident wave;
；
if the VV polarization is used as the calculation condition:
then the first time period of the first time period,；
if HH polarization is used as the calculation condition:
then the first time period of the first time period,；
wherein,is the incident wave vector of the triangular surface element, +.>For the incident electric field at the center of the triangle surface element when the incident wave is of the plane wave type, +.>For pitch angle of incident wave, +.>For azimuth angle of incident wave, +.>Is the basic unit of imaginary number, +.>Wave number of electromagnetic wave, < >>Is a triangle surface element center position vector;
here, the reference frame V, H is the incident plane, V is the electric field direction perpendicular to the incident plane, called vertical polarization, H is the electric field direction parallel to the incident plane, called parallel polarization, VV, HH, etc. are the different polarization combinations of the transmitting and receiving antennas.
If the type of the incident wave is spherical wave, substituting the electric field and the magnetic field on the emitting source of the electromagnetic wave or a certain sealing surface surrounding the emitting source into the following formula to calculate the incident wave vector incident to the center of the triangular surface element ；
；
；
，；
；；；/>
Wherein,is an electromagnetic wave emission source or an incident electric field surrounding any point outside the sealing surface of the emission source,is the electromagnetic wave emission source or the incident magnetic field surrounding any point outside the emission source sealing surface, +.>Is the emission source of electromagnetic wave or the position vector surrounding any point outside the sealing surface of the emission source,jis the basic unit of imaginary number, +.>For the angular frequency of the incident wave, +.> 0 Is magnetic permeability in free space, < >>For the radiation source or for the area of a certain sealing surface surrounding the radiation source, +.>Representing the distance from the source point to the viewpoint, +.>For equivalent current vectors on the emission source or surrounding emission source closure surface +.>Equivalent magnetic current vector epsilon on the sealing surface of the emission source or the surrounding emission source respectively 0 Is the dielectric constant in free space, +.>Is a vector of the face normal>For the electric field vector on the emitter or surrounding emitter envelope, +.>Magnetic field vector on the closure surface of the emission source or surrounding the emission source, respectively, ">A position scalar for an electromagnetic wave emission source or surrounding any point on an emission source sealing surface;
step three, triangular surface element illuminated by incident waveAn incident electric field is determined as a triangular bin illuminated by the incident wave.
Further, referring to fig. 5, a flowchart for tracking a ray according to an embodiment of the present application is provided, where tracking a first ray or a second ray includes the following steps:
Step one, judging whether the starting point coordinates of the rays are inside the current tracking bounding box.
Wherein the ray is a first ray or a second ray.
Step two, if the starting point coordinates of the ray are inside the current tracking bounding box, determining a bounding box of a leaf node closest to the current tracking bounding box on the ray; judging whether the ray intersects with a triangle surface element in a bounding box of the leaf node or not; if the ray intersects a certain triangular surface element in the bounding box of the leaf node, determining and recording the triangular surface element intersected with the ray as the triangular surface element hit by the ray; and stops tracking.
Specifically, determining a bounding box of a leaf node on the ray closest to the current tracking bounding box includes: judging whether the current tracking bounding box is a leaf node bounding box or not; if the current tracking bounding box is not the bounding box of the leaf node, determining a bounding box of the leaf node closest to the current tracking bounding box on the ray through a recursion algorithm; if the current tracking bounding box is a bounding box of the leaf node, taking the current tracking bounding box as a nearest bounding box of the leaf node;
step three, if the ray is not intersected with all the triangular surface elements in the bounding box of the leaf node, determining the triangular surface elements directly illuminated by the ray according to the clue pointers of the surfaces of the bounding box of the leaf node;
Specifically, determining a triangle bin directly illuminated by a ray from a cue pointer of a face of a bounding box of a leaf node, comprising: determining the planes of the bounding box of the leaf node, through which rays pass, from the planes of the bounding box of the leaf node; judging whether the bounding box pointed by the clue pointer of the surface of the bounding box of the ray passing out of the leaf node is the bounding box of the root node or not; if the bounding box pointed by the cue pointer of the surface of the bounding box of the ray passing out of the leaf node is the bounding box of the root node, when the ray is the first ray, the triangle surface element where the ray starting point is positioned is the triangle surface element directly illuminated by the ray; stopping tracking when the ray is the second ray; if the bounding box pointed by the thread pointer of the ray passing out of the face of the bounding box of the leaf node is not the bounding box of the root node, updating the bounding box pointed by the thread pointer of the ray passing out of the face of the bounding box of the leaf node into the current tracking bounding box of the ray, and jumping to judge whether the starting point coordinate of the ray is inside the current tracking bounding box or not so as to continue execution.
Step four, if the starting point coordinates of the ray are not inside the current tracking bounding box, determining a bounding box of a leaf node closest to the current tracking bounding box on the ray; judging whether the ray hits the bounding box of the leaf node or not; if the ray hits the bounding box of the leaf node, jumping to judge whether the ray intersects with the triangle surface element in the bounding box of the leaf node or not so as to continue execution; if the ray misses the bounding box of the leaf node, it is determined whether the ray hits an outer nested triangle primitive of the bounding box of the leaf node.
And fifthly, determining the triangle surface element hit by the ray from all the external nested triangle surface elements according to the judging result.
Specifically, according to the judgment result, determining the triangle element hit by the ray from all the externally nested triangle elements comprises: if the judgment result is that the ray hits the external nested triangular surface element of the bounding box of the leaf node, determining and recording the external nested triangular surface element which is hit as the triangular surface element which is hit by the ray; if the ray misses an external nested triangle of the bounding box of the leaf node, then the triangle directly illuminated by the ray is determined from the thread pointer of the face of the bounding box of the leaf node.
Further, parallelization of the ray tracing process. The parallel thought is to divide different rays to different processes to realize concurrent calculation. Because of differences in the path of each ray, such as direct reflection pop-up, reflection strike to other triangle elements, and different angles of reflection, the time spent by each ray tracking cycle is different, and can be characterized herein as the weight of the ray, representing the computation time. The processing of weights herein takes three parallel strategies: 1) Rays are assigned sequentially without regard to weights. 2) According to the prior unpredictability of the weight, rays are distributed in a random mode; 3) And a master-slave mode is adopted, a management process is established and is responsible for distributing rays, when one process finishes the existing ray tracing and is in an idle state, the management process distributes a new ray, and the cycle is repeated until all the rays are distributed and processed. Since KD-tree greatly accelerates the search time of single ray tracing, that is, the absolute difference of the weights of each ray is very small, the test result shows that the parallel efficiency difference between the strategy 2) and the strategy 3) is not great.
S105, calculating the electromagnetic scattering property of the super-electric large-size structure according to the incident electric field corresponding to the triangular surface element directly illuminated by the incident wave of the electromagnetic wave and the reflected electric field and the reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave.
In the passive region, the PO-based Stratton-Chu integral equation can be written as follows:
；
in the above-mentioned description of the invention,PO solution of triangular surface element directly illuminated by incident wave of electromagnetic wave or illuminated by reflected ray corresponding to incident wave, ++>For the plane wave pitch angle of incidence to the target surface of the super-electric large-size structure, +.>For plane wave azimuth angle incident to the surface of super-electric large-sized structure, < ->Is imaginary number and is->Wave number of electromagnetic wave, < >>For far field distance>Is the unit vector of far field point, +.>Is the emission source of electromagnetic wave or the position scalar of any point on the enclosing surface of the emission source, +.>For the integral area of a single triangular bin, +.>Is a vector of the face normal>Is magnetic permeability in free space, < >>Is the dielectric constant in free space, +.>An incident electric field directly illuminated by an incident wave of an electromagnetic wave, and a sum of the reflected electric fields of triangular elements illuminated by reflected rays of said incident wave, +. >An incident magnetic field that is directly illuminated by an incident wave of electromagnetic waves, and a reflected magnetic field of a triangular surface element that is illuminated by a reflected ray of the incident wave.
Further, the incident electric field is appliedDecomposition into parallel polarized TE waves->And vertical polarization TM wave->Referring to FIG. 6, a schematic diagram of a coordinate system of an incident plane when an incident wave is a plane wave is shown, where +.>Direction and plane normal vector->The plane of construction is the plane of incidence, the direction of vertical polarization of the incident plane wave is specified +.>And parallel polarization direction->The vertical direction and the horizontal direction of the incident wave electric field with respect to the incident plane, respectively. Defining the vertical polarization direction of the reflected radiation>Perpendicular polarization to the incident wave->Consistent (I)>Is the plane wave pitch angle of incidence to the target surface. Thus, we can obtain:
；
；
represents the electric field vector incident at the center of the triangular cell, wherein +.>=，Representing a position vector at the center of the triangle.
Further, calculating a reflection coefficient or a transmission coefficient of the target surface, outputting a reflected electric field or a transmitted electric field, including: reflection coefficient if the metal target surface is not coated with any mediumThe method comprises the steps of carrying out a first treatment on the surface of the If the metal surface is coated with a uniaxial or biaxial dielectric anisotropy medium, the reflection coefficient +.f of an infinite PEC surface-coated anisotropic medium can be solved by spectral domain method >。
Here, when the outer surface of the oversized structure is filled or coated withWhen the anisotropic medium is arranged, the upper part of the conductor plane is provided with uniform free space, and the dielectric constant and the magnetic permeability tensor of the anisotropic medium in the cavity are respectivelyAnd->The method comprises the steps of carrying out a first treatment on the surface of the The two can be used to solve the reflection matrix R of an anisotropic media coated infinite PEC surface. When plane wave->When the anisotropic dielectric material is incident to the PEC plane coated with d thickness, referring to fig. 7, a schematic diagram of a model of coating an anisotropic dielectric layer on an infinite PEC plane is provided in an embodiment of the present application, wherein->And incident wave->Pitch angle in z direction, +.>Is incident wave->The thickness of the anisotropic medium material of the anisotropic medium layer is d, an air layer is arranged above the anisotropic medium layer, a PEC plate is arranged below the anisotropic medium layer, and the anisotropic medium layer is a thick film>And O is the center of the triangle surface element and is the unit vector of the far field point.
In general, there are two methods for calculating the reflective matrix when the anisotropic medium is coated with infinite PEC, the first method is to use a spectral domain method to give an analytical solution, but not all the cases are applicable, the more complex the constitutive relation of the anisotropic medium is, the greater the solution difficulty is, and at present, the study of the subject by domestic and foreign students is still in a starting stage. The second is a differential recursion method proposed by Titchener, which divides the whole anisotropic medium into a plurality of layers for iteration, and the method has the advantages of being applicable to the non-uniform straight layering situation, and the disadvantage that the recursion algorithm consumes too long, so that the method is not applicable to the solution of an electric large-size complex target scattering field. In view of this, only two relatively common computational models of anisotropic media coated PEC are presented herein, single and dual axis dielectric anisotropic media, respectively.
In particular, the reflection matrix solution when uniaxially dielectric anisotropic media are coated on infinite PEC plates. Setting the principal axis of the uniaxial dielectric anisotropy medium in the o-xyz coordinate system as the x-axis, the relative permittivity and relative permeability tensor of which can be expressedAnd->Then the reflection matrix can be expressed as +.>The method comprises the steps of carrying out a first treatment on the surface of the Wherein:
；/>
；
；
，；
the method comprises the steps of carrying out a first treatment on the surface of the k represents the wave number if k has the followingThe subscript number indicates the medium, e.g., k0 indicates wave number in free space, where subscript "0" indicates free space (air); d represents the coating thickness of the metal surface, which is generally relatively thin, on the order of millimeters;
specifically, biaxial dielectric anisotropy medium coated infinite PEC plate reflectance solutions. Biaxial dielectric anisotropy medium whose relative permittivity and relative permeability tensor can be representedAnd->Is consistent, wherein->、、Are not equal to each other. The computational model is consistent with a uniaxial dielectric anisotropy, but is divided into four cases:
a) When k is sx = k sy When=0.00, "sx", "sy" and "sz" in the subscript of k represent eigenvalues of the plane spectrum in the x, y and z directions, respectively;
；
；
b) When k is sx = 0.00，k sy Not equal to 0.00;
；
；
c) When k is sy = 0.00，k sx Not equal to 0.00;
；/>
；
d) When k is sy ≠0.00，k sx Not equal to 0.00;
；
；
；
；
；
；
；
；
；
in summary, for all three cases a), b), and c), the reflection coefficient is calculated using the following formula:
；
For d), its reflection coefficient is calculated using the following formula:
；
further, reflected rays are acquiredA parallel polarized wave electric field and a perpendicular polarized wave electric field of (a), comprising: by using the reflection coefficient obtained by the solution, the TE wave and the TM wave are respectively multiplied by the corresponding reflection coefficients, if the reflection coefficients also have cross polarization component coefficients +.>And->Then it is also necessary to multiply both, so we can: />
；
Wherein,is the reflected field at the center of the triangle bin.
Then, a virtual divergence factor VDF (Virtual divergence factor) is added. From geometrical optics, the electric field represented by each ray can be calculated as follows:
in the above-mentioned description of the invention,is the incident electric field at the mth reflection point rm, +.>Is a matrix of reflection or transmission coefficients at rm, the specific solution of which will be described in the following steps;Is the divergence factor at rm. When the ray is reflected only once, the tube does not diverge, but when the ray is reflected multiple times, DF at the reflection point must be calculated, otherwise the calculation efficiency will be severely reduced.
Here, theAnd->Incident and reflection direction unit vectors, respectively, +.>The equivalent electromagnetic current J at the point is:
；
further, the equivalent current per illuminated bin surface is obtained from the scattering field of an anisotropic medium coated infinite PEC plate And magnetic flow->Comprising: if the target surface is only a pure PEC medium, only the magnetic flow is calculated>That is, if the target is all filled with pure isotropic medium, then the equivalent current +.>And magnetic flow->The calculation is needed, and in any case, the formulas for calculating the electromagnetic currents are the same and all the conditions are satisfied:
；
in the above-mentioned description of the invention,expressed as the dot product of the incident wave and the normal.
Further, estimating electromagnetic scattering characteristics of the anisotropic medium coated target by the following formula, wherein the electromagnetic scattering characteristics comprise a total scattering field of the target in a far field area and RCS of the target;
here, from the Stratton-Chu integration formula, and using far field approximation conditions and Gordon integration method, the PO scattering electric field of triangular bin ABC can be derived:
；
wherein,for the vectors corresponding to the field points, < >>，，，As a free space green's function, i.e. +.>，，，The vectors corresponding to the triangular surface element points A, B and C are respectively. When incident direction +>Perpendicular to the bin and opposite to the scattering direction, i.e. +.>The PO scattering field of the triangle cell ABC will fail, and the scattering field can be written as:
；
wherein the method comprises the steps ofIs the area of triangle primitive ABC. />
In summary, the electromagnetic scattering characteristics of the oversized structure are calculated by the following formula, where the electromagnetic scattering characteristics include the total scattered field of the oversized structure in the far field region and the RCS of the oversized structure:
；
；
；
Wherein,PO solution for triangular surface element illuminated directly by incident wave of electromagnetic wave or by reflected ray corresponding to the incident wave, ++>For plane wave pitch angle incident to the surface of super-electric large-size structure, < >>For plane wave azimuth angle incident to the surface of super-electric large-sized structure, < ->Is imaginary number and is->Wave number of electromagnetic wave, < >>For far field distance>Is the unit vector of far field point, +.>Is the emission source of electromagnetic wave or the position scalar of any point on the enclosing surface of the emission source, +.>For the integral area of a single triangular bin, +.>Is a vector of the face normal>Is magnetic permeability in free space, < >>Is the dielectric constant in free space, +.>Is quilt ofAn incident electric field directly illuminated by an incident wave of electromagnetic waves, and a sum of the reflected electric fields of triangular elements illuminated by reflected rays of said incident wave,/v>For the sum of an incident magnetic field directly illuminated by an incident wave of an electromagnetic wave and a reflected magnetic field of a triangular surface element illuminated by a reflected ray of said incident wave, +.>For the total scattering field of the entire super-electrically large-sized structure in the far-field region, +.>For the number of triangular elements directly illuminated by the initial incident wave of the electromagnetic wave, +.>PO solution for the ith triangle element directly illuminated by the initial incident wave of electromagnetic wave, T is the number of ray tracing, +. >Tracking for the nth ray the PO solutions of all triangular elements illuminated by the reflected rays of said incident wave,/->RCS is an ultra-electrical large-size structure with units of dB/sm,/I>When the type of the incident wave is plane wave, the triangle surface element illuminated by the incident wave of electromagnetic wave and the reflected ray of the incident wave>Is the radar cross section of the oversized structure.
Referring to fig. 8, a schematic diagram of a computing device for electromagnetic scattering characteristics of an oversized structure according to an embodiment of the present application is shown, where the computing device includes:
the extraction module 801 is configured to construct a target model of the oversized structure, and extract coordinate information and a normal vector of each triangular surface element in the target model; the electrical dimension of the super-electrical large-size structure is larger than 300 wavelengths, and the outer surface of the super-electrical large-size structure is coated with an anisotropic medium with the thickness smaller than one wavelength;
a construction module 802, configured to perform KD-Tree binary Tree construction on the target model according to coordinate information of all triangular surface elements; in the constructed KD-Tree Tree structure, each node bounding box consists of 6 faces, and each face corresponds to a clue pointer; the cue pointer of each face points to a node bounding box adjacent to the respective face;
An updating module 803, configured to update the cue pointers of the faces of each node bounding box according to the relative positional relationship between the 6 faces of each node bounding box and the partition faces of the node bounding box pointed by the corresponding cue pointers;
a determining module 804, configured to determine, according to the bin normal vector, the constructed KD-Tree, and the updated cue pointers of each surface of each node bounding box, an incident electric field corresponding to a triangular bin directly illuminated by an incident wave of the electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular bin illuminated by a reflected ray of the incident wave, in all triangular bins; electromagnetic waves are in the millimeter or lower wave band;
a calculation module 805 for calculating electromagnetic scattering characteristics of the oversized structure based on an incident electric field corresponding to the triangular cells directly illuminated by the incident wave of the electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular cells illuminated by the reflected ray of the incident wave.
The embodiment of the application provides a calculation device for the electromagnetic scattering property of an ultra-electric large-size structure, which can calculate the electromagnetic scattering property of the ultra-electric large-size structure, shortens the time when calculating the electromagnetic scattering property of the ultra-electric large-size structure with the electric size larger than 300 wavelengths and the outer surface coated with an anisotropic medium with the thickness smaller than one wavelength, and improves the efficiency of calculating the electromagnetic scattering property of the ultra-electric large-size structure.
As shown in fig. 9, an electronic device 900 provided in an embodiment of the present application includes: the device comprises a processor 901, a memory 902 and a bus, wherein the memory 902 stores machine-readable instructions executable by the processor 901, and when the electronic device is running, the processor 901 and the memory 902 communicate through the bus, and the processor 901 executes the machine-readable instructions to perform the steps of the method for calculating the electromagnetic scattering property of the super-electric large structure.
Specifically, the memory 902 and the processor 901 can be general-purpose memories and processors, and the method for calculating the electromagnetic scattering characteristics of the oversized structure can be performed when the processor 901 runs a computer program stored in the memory 902, without being limited thereto.
Corresponding to the above method for calculating the electromagnetic scattering property of the super-electric large-sized structure, the embodiment of the application also provides a computer readable storage medium, on which a computer program is stored, which when executed by a processor performs the steps of the above method for calculating the electromagnetic scattering property of the super-electric large-sized structure.
The foregoing is merely a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes or substitutions are covered in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (11)

1. A method for calculating electromagnetic scattering characteristics of an oversized structure, the method comprising:
constructing a target model of the super-electric large-size structure, and extracting coordinate information of each triangular surface element and a surface element normal vector in the target model; the electrical dimension of the super-electrical large-size structure is larger than 300 wavelengths, and the outer surface of the super-electrical large-size structure is coated with an anisotropic medium with the thickness smaller than one wavelength;
constructing a KD-Tree binary Tree for the target model according to the coordinate information of all triangular surface elements; in the constructed KD-Tree Tree structure, each node bounding box consists of 6 faces, and each face corresponds to a clue pointer; the cue pointer of each face points to a node bounding box adjacent to the respective face;
updating the cue pointers of the faces of each node bounding box according to the relative position relation between the 6 faces of each node bounding box and the partitioned faces of the node bounding box pointed by the corresponding cue pointers, comprising: creating a null line pointer for the root node bounding box, taking the null line pointer as input, and inheriting the cue pointer of the father node to the left child node and the right child node; according to plane information of the internal division surfaces of each father node bounding box, a right cue pointer of a left child node is pointed to the right child node, and a left cue pointer of the right child node is pointed to the left child node so as to complete a cue process and obtain cue pointers of each surface of each node bounding box; judging whether the faces are parallel to the partition faces of the node bounding boxes pointed by the corresponding cue pointers according to each face of each node bounding box; if the surface is parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer, pointing the cue pointer corresponding to the surface to the left sub-node bounding box or the right sub-node bounding box corresponding to the node bounding box pointed by the corresponding cue pointer; if the surface is not parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer, and the coordinate of the partition surface of the node bounding box pointed by the corresponding cue pointer is larger than the coordinate of the node bounding box where the surface is located, the cue pointer corresponding to the surface is pointed to the right child node corresponding node bounding box of the node bounding box pointed by the corresponding cue pointer; if the surface is not parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer and the coordinate of the partition surface of the node bounding box pointed by the corresponding cue pointer is smaller than the coordinate of the node bounding box where the surface is located, pointing the cue pointer corresponding to the surface to the node bounding box corresponding to the left child node of the node bounding box pointed by the cue pointer corresponding to the surface so as to finish optimization of the cue pointer;
Determining an incident electric field corresponding to a triangular surface element directly illuminated by an incident wave of an electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular surface element illuminated by a reflected ray of the incident wave in all triangular surface elements according to the surface element normal vector, the constructed KD-Tree and the updated clue pointers of each surface of each node bounding box; the electromagnetic wave is in a wave band below millimeter;
and calculating the electromagnetic scattering property of the super-electric large-size structure according to the incident electric field corresponding to the triangular surface element directly illuminated by the incident wave of the electromagnetic wave, and the reflected electric field and the reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave.
2. The method for calculating electromagnetic scattering characteristics of an oversized structure according to claim 1, wherein constructing the KD-Tree binary Tree of the target model according to the coordinate information of all triangular surface elements includes:
constructing an axis alignment bounding box containing all triangular surface elements according to the coordinate information of all triangular surface elements to obtain a bounding box corresponding to the root node;
determining a segmentation surface of the bounding box corresponding to the root node according to the number of triangle surface elements and the number of vertexes in the bounding box corresponding to the root node and the projection length of the bounding box corresponding to the root node on each coordinate axis;
Dividing the root node bounding box by dividing the bounding box corresponding to the root node to obtain left and right child node bounding boxes corresponding to the root node; the face information in the bounding box corresponding to the root node is pressed into the bounding boxes corresponding to the left child node and the right child node; recursion left and right child node bounding boxes, and exiting when reaching a termination condition;
aiming at each node bounding box in the currently constructed KD-Tree; judging whether the node bounding box meets the termination condition or not; wherein the termination condition includes: i. the number of triangular surface elements in the node bounding box is smaller than the preset number; ii. The depth corresponding to the node bounding box is larger than a preset depth threshold; iii, the cost of the surface area heuristic SAH corresponding to the node bounding box when the node bounding box is not segmented is lower than the cost of the SAH corresponding to the segmented node bounding box; iv, the distance between the dividing plane corresponding to the divided node bounding box and the six faces of the node bounding box is smaller than the preset distance;
if the node bounding box does not meet the termination condition, determining a segmentation surface of the node bounding box according to the number of triangular surface elements in the node bounding box, the number of vertexes and the projection length of the triangle surface elements on each coordinate axis, and continuing segmentation; otherwise, defining the node bounding box as a leaf node or a null node bounding box, stopping segmentation, and pressing the face information in the leaf node into the bounding box.
3. The method for calculating electromagnetic scattering properties of an oversized structure according to claim 2, wherein the dividing plane of the node bounding box is determined by:
determining a coordinate point corresponding to one half of the projection length of the node bounding box on each coordinate axis as a first search boundary of the optimal segmentation plane;
determining a second search boundary of the optimal segmentation surface according to one half of the number of vertexes of triangular surface elements in the node bounding box;
determining the first search boundary and the second search boundary as boundaries of search intervals of the optimal segmentation surface;
traversing three axes of X, Y and Z, calculating SAH costs of all surface area heuristic strategies in the search interval, and determining a segmentation plane with the minimum SAH costs as an optimal segmentation plane.
4. The method for calculating electromagnetic scattering characteristics of an oversized structure according to claim 1, wherein the determining, from among all triangular cells, an incident electric field corresponding to a triangular cell directly illuminated by an incident wave of an electromagnetic wave, and a reflected electric field and a reflected magnetic field of a triangular cell illuminated by a reflected ray of the incident wave, based on the bin normal vector, the constructed KD-Tree, and the updated cue pointers for each face of each node bounding box, comprises:
If the distance between the emitting source of the incident wave and the target model is greater than the preset distance, the incident wave is taken as a plane wave, and the pitch angle of the plane wave incident to the center of the triangular surface element is determinedθAnd azimuth angleφCalculating the incident wave vector；
If the distance between the emitting source of the incident wave and the target model is smaller than the preset distance, the incident wave is taken as a spherical wave, and an incident wave vector is calculated according to the electric field and the magnetic field on the emitting source of the incident wave or a sealing surface surrounding the emitting source；
According to the incident wave vectorAnd determining an incident electric field corresponding to the triangular surface element directly illuminated by the incident wave of the electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave, wherein the normal vector of the surface element, the KD-Tree which is built and the updated cue pointers of 6 surfaces of each node bounding box.
5. The method for calculating electromagnetic scattering properties of an oversized structure according to claim 4 wherein the vector of incident wavesDetermining an incident electric field corresponding to a triangular surface element directly illuminated by an incident wave of an electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular surface element illuminated by a reflected ray of the incident wave, wherein the method comprises the following steps of:
Judging the incident wave vector incident on the center of each triangular surface elementVector normal to the triangle bin>Whether or not to satisfy->·<0.00; if not, judging the triangular surface element as an occluded surface element, and discarding the occluded surface element;
if so, taking the center of the triangle surface element as the ray starting point, andfor the propagation direction of ray tracing, rays are according to the characteristic that light propagates along a straight line>Tracking and adding said rays +_>Determining as a first ray; if the first ray does not intersect any triangular surface element in all node bounding boxes of the constructed KD-tree, the triangular surface element is identified as the triangular surface element illuminated by the incident wave, and an incident electric field corresponding to the triangular surface element illuminated by the incident wave is obtained; otherwise, the triangular surface element is considered as an occluded surface element and is discarded;
following the law of reflection in geometrical optics, the incident waveGenerating a corresponding reflected ray in the illuminated triangular surface element; determining the reflected ray as a second ray, and tracking the second ray by taking the illuminated triangle element center as the starting point of the second ray to obtain allA triangular surface element illuminated by the second ray, and a reflected electric field and a reflected magnetic field of the triangular surface element illuminated by the second ray;
If the tracking frequency is smaller than the preset frequency and the second ray intersects the target model, the second ray is used as a new incident waveAnd jumps to said following reflection law in geometrical optics, when said incident wave +.>A corresponding reflected ray is generated in the illuminated triangular bin to continue execution.
6. The method for calculating electromagnetic scattering properties of an oversized structure according to claim 5, wherein an incident wave vector incident on a triangle cell center is calculatedAn incident electric field of a triangular cell illuminated by the incident wave, comprising:
if the type of the incident wave is plane wave, substituting the pitch angle and the azimuth angle of the incident wave into the following formulas to calculate the vector of the incident wave incident to the center of the triangular surface elementAn incident electric field of a triangular cell illuminated by the incident wave;
；
if the VV polarization is used as the calculation condition:
then the first time period of the first time period,；
if HH polarization is used as the calculation condition:
then the first time period of the first time period,；
wherein,is the incident wave vector of the triangular surface element, +.>For the incident electric field at the center of the triangle surface element when the incident wave is of the plane wave type, +.>For pitch angle of incident wave, +.>For azimuth angle of incident wave, +.>Is the basic unit of imaginary number, +. >Wave number of electromagnetic wave, < >>Is a triangle surface element center position vector;
if the type of the incident wave is spherical wave, substituting the electric field and the magnetic field on the emitting source of the electromagnetic wave or a certain sealing surface surrounding the emitting source into the following formula to calculate the incident wave vector incident to the center of the triangular surface element；
；；
，；
；；；
Wherein,is the incident electric field of the electromagnetic wave emission source or surrounding any point outside the sealing surface of the emission source, +.>Is the electromagnetic wave emission source or the incident magnetic field surrounding any point outside the emission source sealing surface, +.>Is the emission source of electromagnetic wave or the position vector surrounding any point outside the sealing surface of the emission source,jis the basic unit of imaginary number, +.>For the angular frequency of the incident wave, +.> 0 Is magnetic permeability in free space, < >>For the emission source orWhich encloses the area of a certain sealing surface of the emission source, < >>Representing the distance from the source point to the viewpoint, +.>For equivalent current vectors on the emission source or surrounding emission source closure surface +.>Equivalent magnetic current vector epsilon on the sealing surface of the emission source or the surrounding emission source respectively 0 Is the dielectric constant in free space, +.>Is a vector of the face normal>For the electric field vector on the emitter or surrounding emitter envelope, +.>For the magnetic field vector on the emission source or surrounding emission source closure surface, +. >A position scalar for an electromagnetic wave emission source or surrounding any point on an emission source sealing surface;
triangular surface elements to be illuminated by the incident waveAn incident electric field is determined as a triangular bin illuminated by the incident wave.
7. The method of claim 5, wherein tracking the first or second radiation, comprises:
judging whether the starting point coordinates of the rays are inside the current tracking bounding box or not; the ray is a first ray or the second ray;
if the starting point coordinates of the ray are inside the current tracking bounding box, determining a bounding box of a leaf node on the ray closest to the current tracking bounding box; judging whether the ray intersects with a triangle surface element in a bounding box of the leaf node or not; if the ray intersects a certain triangular surface element in the bounding box of the leaf node, determining and recording that the triangular surface element intersected with the ray is the triangular surface element hit by the ray; and stopping tracking;
if the ray does not intersect all the triangular surface elements in the bounding box of the leaf node, determining the triangular surface elements directly illuminated by the ray according to the cue pointer of the surface of the bounding box of the leaf node;
If the starting point coordinates of the ray are not inside the current tracking bounding box, determining a bounding box of a leaf node on the ray closest to the current tracking bounding box; judging whether the ray hits the bounding box of the leaf node or not; if the ray hits the bounding box of the leaf node, jumping to judge whether the ray intersects with a triangle primitive in the bounding box of the leaf node or not so as to continue execution; if the ray does not hit the bounding box of the leaf node, judging whether the ray hits the external nested triangle element of the bounding box of the leaf node or not;
and determining the triangle which is hit by the ray from all the externally nested triangle elements according to the judging result.
8. The method of claim 7, wherein determining a bounding box of a leaf node on the ray closest to a current tracking bounding box comprises:
judging whether the current tracking bounding box is a leaf node bounding box or not; if the current tracking bounding box is not the bounding box of the leaf node, determining a bounding box of the leaf node closest to the current tracking bounding box on the ray through a recursion algorithm; if the current tracking bounding box is a bounding box of the leaf node, taking the current tracking bounding box as a nearest bounding box of the leaf node;
The determining a triangle surface element directly illuminated by the ray according to the cue pointer of the surface of the bounding box of the leaf node comprises:
determining the ray from each face of the bounding box of the leaf node to penetrate out of the face of the bounding box of the leaf node; judging whether the bounding box pointed by the clue pointer of the surface of the bounding box of the leaf node, through which the ray passes, is the bounding box of the root node or not; if the bounding box pointed by the thread pointer of the surface of the bounding box of the leaf node, which is penetrated by the ray, is the bounding box of the root node, when the ray is the first ray, the triangle surface element where the ray starting point is positioned is the triangle surface element directly illuminated by the ray; stopping tracking when the ray is a second ray; if the bounding box pointed by the thread pointer of the ray passing out of the face of the bounding box of the leaf node is not the bounding box of the root node, updating the bounding box pointed by the thread pointer of the ray passing out of the face of the bounding box of the leaf node into the current tracking bounding box of the ray, and jumping to judge whether the starting point coordinate of the ray is inside the current tracking bounding box or not so as to continue execution.
9. The method for calculating electromagnetic scattering properties of an oversized structure according to claim 7, wherein determining a triangle that is hit by the ray from all externally nested triangles according to the determination result comprises:
if the judgment result is that the ray hits the external nested triangle surface element of the bounding box of the leaf node, determining and recording the external nested triangle surface element which is hit as the triangle surface element which is hit by the ray;
if the ray misses an external nested triangle of the bounding box of the leaf node, determining a triangle directly illuminated by the ray according to a cue pointer of a face of the bounding box of the leaf node.
10. The method according to claim 6, wherein calculating the electromagnetic scattering property of the oversized structure based on the incident electric field corresponding to the triangular cell directly illuminated by the incident wave of the electromagnetic wave, and the reflected electric field and the reflected magnetic field of the triangular cell illuminated by the reflected ray of the incident wave, comprises:
calculating electromagnetic scattering characteristics of the super-electric large-size structure by the following formula, wherein the electromagnetic scattering characteristics comprise a total scattering field of the super-electric large-size structure in a far field area and RCS of the super-electric large-size structure;
；
；
；
Wherein,PO solution for triangular surface element illuminated directly by incident wave of electromagnetic wave or by reflected ray corresponding to the incident wave, ++>For plane wave pitch angle incident to the surface of super-electric large-size structure, < >>For plane wave azimuth angle incident to the surface of super-electric large-sized structure, < ->Is imaginary number and is->Wave number of electromagnetic wave, < >>For far field distance>Is the unit vector of far field point, +.>For the integral area of a single triangular bin, +.>Is a vector of the face normal>Is magnetic permeability in free space, < >>Is the dielectric constant in free space, +.>An incident electric field directly illuminated by an incident wave of an electromagnetic wave, and a sum of the reflected electric fields of triangular elements illuminated by reflected rays of said incident wave, +.>For the sum of an incident magnetic field directly illuminated by an incident wave of an electromagnetic wave and a reflected magnetic field of a triangular surface element illuminated by a reflected ray of said incident wave, +.>For the total scattering field of the entire super-electrically large-sized structure in the far-field region, +.>Is the initial incident wave of the electromagnetic waveThe number of directly illuminated triangular elements, +.>PO solution for the ith triangle element directly illuminated by the initial incident wave of electromagnetic wave, T is the number of ray tracing, +. >Tracking for the nth ray the PO solutions of all triangular elements illuminated by the reflected rays of said incident wave,/->RCS is an ultra-electrical large-size structure with units of dB/sm,/I>When the type of the incident wave is plane wave, the triangle element illuminated by the incident wave of electromagnetic wave and by the reflected ray of the incident wave>Is the radar cross section of the oversized structure, RCS is +.>Is a triangle bin center position vector.
11. A computing device for electromagnetic scattering properties of an oversized structure, the device comprising:
the extraction module is used for constructing a target model of the super-electric large-size structure and extracting coordinate information and a surface element normal vector of each triangular surface element in the target model; the electrical dimension of the super-electrical large-size structure is larger than 300 wavelengths, and the outer surface of the super-electrical large-size structure is coated with an anisotropic medium with the thickness smaller than one wavelength;
the construction module is used for constructing a KD-Tree binary Tree for the target model according to the coordinate information of all the triangular surface elements; in the constructed KD-Tree Tree structure, each node bounding box consists of 6 faces, and each face corresponds to a clue pointer; the cue pointer of each face points to a node bounding box adjacent to the respective face;
The updating module is configured to update the cue pointers of the respective faces of the bounding boxes according to the relative positional relationship between the 6 faces of the bounding boxes and the partition faces of the bounding boxes pointed to by the corresponding cue pointers, and includes: creating a null line pointer for the root node bounding box, taking the null line pointer as input, and inheriting the cue pointer of the father node to the left child node and the right child node; according to plane information of the internal division surfaces of each father node bounding box, a right cue pointer of a left child node is pointed to the right child node, and a left cue pointer of the right child node is pointed to the left child node so as to complete a cue process and obtain cue pointers of each surface of each node bounding box; judging whether the faces are parallel to the partition faces of the node bounding boxes pointed by the corresponding cue pointers according to each face of each node bounding box; if the surface is parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer, pointing the cue pointer corresponding to the surface to the left sub-node bounding box or the right sub-node bounding box corresponding to the node bounding box pointed by the corresponding cue pointer; if the surface is not parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer, and the coordinate of the partition surface of the node bounding box pointed by the corresponding cue pointer is larger than the coordinate of the node bounding box where the surface is located, the cue pointer corresponding to the surface is pointed to the right child node corresponding node bounding box of the node bounding box pointed by the corresponding cue pointer; if the surface is not parallel to the partition surface of the node bounding box pointed by the corresponding cue pointer and the coordinate of the partition surface of the node bounding box pointed by the corresponding cue pointer is smaller than the coordinate of the node bounding box where the surface is located, pointing the cue pointer corresponding to the surface to the node bounding box corresponding to the left child node of the node bounding box pointed by the cue pointer corresponding to the surface so as to finish optimization of the cue pointer;
The determining module is used for determining an incident electric field corresponding to the triangular surface element directly illuminated by the incident wave of the electromagnetic wave, and a reflected electric field and a reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave in all the triangular surface elements according to the normal vector of the surface element, the constructed KD-Tree and the updated clue pointers of each surface of each node bounding box; the electromagnetic wave is in a wave band below millimeter;
and the calculation module is used for calculating the electromagnetic scattering property of the super-electric large-size structure according to the incident electric field corresponding to the triangular surface element directly illuminated by the incident wave of the electromagnetic wave, and the reflected electric field and the reflected magnetic field of the triangular surface element illuminated by the reflected ray of the incident wave.
CN202311640083.6A 2023-12-04 2023-12-04 Method and device for calculating electromagnetic scattering characteristics of super-electric large-size structure Active CN117350083B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311640083.6A CN117350083B (en) 2023-12-04 2023-12-04 Method and device for calculating electromagnetic scattering characteristics of super-electric large-size structure

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311640083.6A CN117350083B (en) 2023-12-04 2023-12-04 Method and device for calculating electromagnetic scattering characteristics of super-electric large-size structure

Publications (2)

Publication Number Publication Date
CN117350083A CN117350083A (en) 2024-01-05
CN117350083B true CN117350083B (en) 2024-03-29

Family

ID=89366969

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202311640083.6A Active CN117350083B (en) 2023-12-04 2023-12-04 Method and device for calculating electromagnetic scattering characteristics of super-electric large-size structure

Country Status (1)

Country Link
CN (1) CN117350083B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118135228B (en) * 2024-04-30 2024-09-13 中国人民解放军战略支援部队航天工程大学 Electromagnetic shielding judging method based on face element normal and ray triangle intersection algorithm

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7558706B1 (en) * 1997-06-11 2009-07-07 Siemens Aktiengesellschaft Computer-aided simulation method for determining the electromagnetic field of a body
CN115754959A (en) * 2022-11-04 2023-03-07 中国人民解放军空军工程大学 Method for establishing target-environment composite radar scattering cross section calculation model
CN116992660A (en) * 2023-07-31 2023-11-03 西安电子科技大学 Electromagnetic scattering simulation method of moving target based on following octree SBR

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7558706B1 (en) * 1997-06-11 2009-07-07 Siemens Aktiengesellschaft Computer-aided simulation method for determining the electromagnetic field of a body
CN115754959A (en) * 2022-11-04 2023-03-07 中国人民解放军空军工程大学 Method for establishing target-environment composite radar scattering cross section calculation model
CN116992660A (en) * 2023-07-31 2023-11-03 西安电子科技大学 Electromagnetic scattering simulation method of moving target based on following octree SBR

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
An Improved Ray-Tracing Algorithm for SBR-Based EM Scattering Computation of Electrically Large Targets;Tian-Tian Feng 等;IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS;第20卷(第5期);第818-822页 *
GPU-Based Combination of GO and PO for Electromagnetic Scattering of Satellite;Peng-Bo Wei 等;IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION;第60卷(第11期);第5278-5285页 *
Stackless KD-Tree Traversal For Ray Tracing;Fubing Li 等;2021 2nd International Conference on Electronics, Communications and Information Technology (CECIT);第1168-1172页 *
基于KD-Tree的组合目标电磁散射快速算法;张杨 等;兵工学报(S2);第173-177页 *
海面舰船复合场景电磁散射模型与应用研究;李金星 等;空间电子技术;第19卷(第2期);第38-47页 *

Also Published As

Publication number Publication date
CN117350083A (en) 2024-01-05

Similar Documents

Publication Publication Date Title
Tao et al. GPU-based shooting and bouncing ray method for fast RCS prediction
CN117350083B (en) Method and device for calculating electromagnetic scattering characteristics of super-electric large-size structure
Xu et al. Bidirectional analytic ray tracing for fast computation of composite scattering from electric-large target over a randomly rough surface
US7348975B2 (en) Applications of interval arithmetic for reduction of number of computations in ray tracing problems
CN101216556B (en) Electrically Large complex target and rugged face background composite electromagnetic scattering numerical value emulation method
CN106772301A (en) A kind of multilayer non-parallel interfaces medium electromagnetic scattering simulation algorithm based on medium ray tracing
Tao et al. Adaptive aperture partition in shooting and bouncing ray method
Feng et al. An improved ray-tracing algorithm for SBR-based EM scattering computation of electrically large targets
KR20120032159A (en) Image processing apparatus and method
Gao et al. Mapping the SBR and TW-ILDCs to heterogeneous CPU-GPU architecture for fast computation of electromagnetic scattering
CN113158485A (en) Electromagnetic scattering simulation method for electrically large-size target under near-field condition
Gao et al. Fast RCS prediction using multiresolution shooting and bouncing ray method on the GPU
Cakir et al. An FDTD-based parallel virtual tool for RCS calculations of complex targets
CN109861775B (en) Propagation path searching method and device
Xu et al. Acceleration of shooting and bouncing ray method based on OptiX and normal vectors correction
Dong et al. An improved go-po/ptd hybrid method for em scattering from electrically large complex targets
Dong et al. Application of CUDA-accelerated GO/PO method in calculation of electromagnetic scattering from coated targets
Lozano et al. Efficient combination of acceleration techniques applied to high frequency methods for solving radiation and scattering problems
Na et al. A Multiple Huygens Surface-Based Ray Tracing Framework With GPU Acceleration
Tao et al. From CPU to GPU: GPU-based electromagnetic computing (GPUECO)
CN109558568A (en) A kind of target RCS calculation method based on CUDA
Khrychov et al. Facet model processing for complex shape object scattering calculation
Guo et al. Electromagnetic Scattering of Electrically Large Ship above Sea Surface with SBR‐SDFM Method
Park et al. Improvement of RCS prediction using modified angular division algorithm
Breglia et al. Comparison of Acceleration Data Structures for Electromagnetic Ray-Tracing Purposes on GPUs [EM Programmer's Notebook]

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant