A modeling method, system, device and medium for simulation calculation of a near-field radar scattering cross section based on a terahertz frequency band

Abstract

A modeling method, system, equipment, and medium for near-field radar cross section (RCS) simulation calculation based on the terahertz band are disclosed. The method involves: preprocessing the surface element size of a 3D model according to near-field characteristics; calculating the unit normal vector of each surface element; solving the scattered light field of a single surface element at different incident angles θ using Kirchhoff approximation theory and storing the corresponding data; determining incident occlusion for discrete surface elements and obtaining the scattered light field data at the corresponding angle by the angle between the incident light field and the unit normal vector of the surface element; substituting this data into the RCS far-field scattering calculation formula to solve for the radar cross section Δσ of a single surface element; and obtaining the total radar cross section σ using the complex scattering field superposition formula of each scattering center of the RCS. sum Radar attenuation is introduced for correction, resulting in the overall near-field RCS calculation model σ. g By changing the wavelength, target material, and incident angle, and using a near-field RCS calculation model, RCS results under different conditions are obtained. The system, equipment, and medium are based on the method to realize the modeling of near-field radar cross section simulation calculation based on the terahertz band. This invention solves the problem of large number of small facets and difficult calculation when measuring electrically large targets in the near field due to short wavelength, and improves the applicability of the near-field RCS model.

Description

Technical Field

[0001] This invention relates to the field of near-field detection technology, and in particular to a modeling method, system, device and medium for near-field radar cross section simulation calculation based on the terahertz frequency band. Background Technology

[0002] The calculation of the generalized radar cross section requires that the distance R between the target and the detection radar approaches infinity, and that the incident wave illuminating the target is a uniform plane wave, i.e., R ≥ 2D. 2 / λ is needed to obtain the radar cross section (RCS) of a target, where D is the maximum size of the target. However, the wavelength in the terahertz band is extremely short, and traditional far-field measurements require distances of tens of meters or even longer, making them difficult to achieve in the laboratory. Therefore, near-field measurements are particularly important for rapidly measuring the RCS value of electrically large targets.

[0003] Compared to microwaves, the terahertz band has a shorter wavelength, and the electrical size of a target in this band differs from that in microwaves, resulting in different electromagnetic scattering characteristics. This provides information on target scattering properties that differ from those in microwaves. In the terahertz band, sensitivity to fine surface structures of targets is enhanced. For example, a target considered smooth in microwaves may appear rough in the terahertz band because the wavelength scale becomes smaller for the same target. When measuring full-size targets, the terahertz band offers higher resolution than microwaves, allowing for finer resolution of details such as shape, size, and structure, thus enabling more accurate identification of different target types.

[0004] For the measurement and calculation of electrically large targets, traditional far-field conditions are difficult to meet, requiring the transformation of near-field measurement data into far-field data. At the same time, achieving higher resolution significantly increases the computational load. Therefore, modeling for single-station radar scattering simulation calculations of near-field measurements is of great importance.

[0005] In their patent application CN219143081U, entitled "Near-field RCS Measurement Device Based on MIMO", Li Bo et al. used MIMO radar to rotate and scan the target under near-field conditions to obtain the near-field RCS. However, this method only considered the calculation of near-field radar cross section RCS under microwave wavelength, and did not consider the problems of the surge in the number of surface elements and the calculation difficulty caused by the short wavelength of electrically large targets in the terahertz band. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to propose a modeling method, system, device, and medium for near-field radar cross section simulation calculation based on the terahertz band. This method combines the phase information of a single small near-field element with the radar attenuation during propagation to obtain a near-field RCS calculation model for electrically large targets in the terahertz band. This allows for the rapid calculation of the RCS information of electrically large targets in the near field using methods such as scattering measurement. The present invention solves the problem of the large amount of data and computational difficulty in the terahertz band when measuring electrically large targets in the near field, thus improving the applicability of the model.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A modeling method for simulating near-field radar cross section calculation based on the terahertz frequency band, the method comprising:

[0009] Step 1, Surface Partitioning and Unit Normal Vector Calculation: Based on the influence of the near field on the 3D target, surface partitioning is performed to obtain multiple small surfaces with a partitioning scale of λ / 3. Simultaneously, the unit normal vector of each small surface is calculated.

[0010] Step 2: Solve for individual small surface elements under different incident light fields using Kirchhoff approximation theory. With the unit normal vector of the surface element The angle between them, i.e. the scattered light field at different incident angles. And store the incident angle θ and the scattered light field data;

[0011] Step 3: Under different incident conditions, determine the incident occlusion of discrete three-dimensional target elements to obtain effective scattering elements, and then analyze the incident light field. Normal to the unit of surface The angle is obtained from the stored data to retrieve the scattered light field at the corresponding angle.

[0012] Step 4: Based on the radar cross section (RCS) far-field scattering calculation formula, solve for the scattering cross section Δσ under a single small surface element;

[0013] Step 5: Superimpose the radar cross sections (RCS) of the small surface elements to obtain the total radar cross section σ. sum ;

[0014] Step 6, introduce radar attenuation The calculation model σ of the entire near-field radar cross section (RCS) is obtained. g .

[0015] The specific method for step 1 is as follows:

[0016] When a three-dimensional target is in the near-field region of the measuring radar, the target is triangularly divided into facets. Using the side length of the facet as the division scale, the side length of the target is uniformly divided to construct several facets, which are used to represent the target surface.

[0017] Based on the three vertices v1, v2, v3 of the small facet obtained by partitioning, we have:

[0018]

[0019]

[0020] in, It is the vector pointing from vertex v1 to vertex v2. It is the vector pointing from vertex v1 to vertex v3. It is the unit normal vector of the small facet.

[0021] The specific method for step 2 is as follows:

[0022] Incident light field for:

[0023]

[0024] Where E0 is the amplitude, and k = 2π / λ is the wave number. The distance from the radar to the facet element is given by j, which represents the imaginary unit.

[0025] Based on the Kirchhoff approximation theory, the scattered light field of each small surface element Δs is calculated.

[0026]

[0027] Where a0 is the scattering coefficient and K is the proportionality constant, expressed as: R is the distance between the target center and the receiving point. Indicates phase change, The vector representing the direction of the unit wave vector of the incident wave;

[0028] Customize the incident angle range and step size, calculate the scattered electric field under different incident angles, and record the incident angle and scattered electric field.

[0029] The specific method for step 3 is as follows:

[0030] use The algorithm first checks the intersection of the facet element with the ray. Any point P on the facet element can be represented as:

[0031]

[0032] Where p is the coordinate of point P, and p′ is the coordinate of any point in the small facet element other than point P. It is the unit normal vector of the small facet.

[0033] Let ray 1 represent the light traveling from radar position o along the unit wave vector. Starting from the ray, the equation can be expressed as:

[0034]

[0035] Where t is a variable, if ray 1 intersects the small surface element at point P, t can be solved, that is:

[0036]

[0037] At this point, the range of t is 0 ≤ t ≤ +∞.

[0038] After the intersection judgment, if ray 1 intersects with other small facets and the distance between them is less than the distance from ray 1 to the small facet where point P is located, the small facet where point P is located is judged to be occluded, that is, the small facet where point P is located cannot reflect effectively; conversely, if ray 1 intersects with other small facets and the distance between them is greater than the distance between ray 1 and the small facet where point P is located, the small facet where point P is located is judged to be unoccluded, that is, the small facet where point P is located can reflect effectively.

[0039] After intersecting and occluding small facets, the scattered light field at the corresponding angle is read from the stored data by the angle between the incident light and the normal of the facet unit, thus obtaining...

[0040] The specific method for step 4 is as follows:

[0041] According to the formula for calculating the far-field scattering of radar cross section (RCS):

[0042]

[0043] The formula for the radar cross section (RCS) of a single small surface element is:

[0044]

[0045] Where, Δσ n Let R be the radar cross section (RCS) of the nth small element. n Let n be the distance between the nth facet and the radar.

[0046] The specific method for step 5 is as follows:

[0047] The phase information of each facet element is incorporated into the radar cross section (RCS) formula for a single facet element, and the RCS of the facet elements are superimposed to obtain the total radar cross section σ. sum :

[0048]

[0049] Where N is the total number of facets.

[0050] The specific method for step 6 is as follows:

[0051] Based on the actual radar illumination propagation process, energy will attenuate to a certain extent, and radar attenuation will be introduced. for:

[0052]

[0053] Where P0 is the radar transmit power, α is the attenuation coefficient, and R n Let θ be the distance between the nth facet and the radar. These are the zenith angle and the azimuth angle, respectively.

[0054] The formula for the near-field radar cross section of a target, based on phase superposition and radar propagation attenuation, is as follows:

[0055]

[0056] A modeling method for simulating near-field radar cross section calculation based on the terahertz frequency band includes:

[0057] The surface element partitioning module is used in step 1 to partition the surface of the target model into triangular surface elements based on the near-field characteristics, and to calculate the unit normal vector of the surface element based on the vertices of the partitioned surface elements.

[0058] The surface element calculation module is used in step 2 to calculate the scattered light field of a single small surface element under different incident angles based on the Kirchhoff approximation theory. And store the data;

[0059] The discrete surface element calculation module is used in step 3. Based on the surface element calculation module, it performs intersection and occlusion judgment on the divided small surface elements and rays, and calculates the scattered light field of the small surface elements according to the incident angle.

[0060] The target radar cross section (RCS) calculation module is used in steps 4 to 6 to substitute the scattered light field of the surface element under different incident angles into the far-field scattering calculation formula of the RCS, thus obtaining the RCS of a single small surface element. Considering near-field phase information and radar attenuation, the total scattering cross section σ is obtained by using the complex scattering superposition formula of each scattering center of the RCS. sum .

[0061] An electronic device, comprising:

[0062] At least one processor;

[0063] And, a memory communicatively connected to the at least one processor;

[0064] The memory stores instructions that can be executed by the at least one processor, which are executed by the at least one processor to enable the at least one processor to perform a modeling method for near-field radar cross section simulation calculation based on the terahertz band, as described in any one of steps 1 to 6.

[0065] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements a modeling method for near-field radar cross section simulation calculation based on the terahertz frequency band, as described in any one of steps 1 to 6.

[0066] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0067] 1. Solving the problem of near-field calculation for electrically large targets in the terahertz band and improving computational efficiency. Addressing the issue of excessive computational load caused by the surge in the number of facets for electrically large targets in the terahertz band due to the short wavelength, this invention optimizes the computational process through the following technical means: Step 1: Preprocessing the facet size of the 3D model based on near-field characteristics, setting the subdivision scale to λ / 3 to ensure that each small facet is located in the radar far-field region, satisfying computational accuracy while avoiding excessive subdivision; Step 2: Establishing a database of scattered light fields for individual small facets using Kirchhoff approximation theory, directly calling the data at the corresponding angle in subsequent calculations to avoid redundant solutions and further improve efficiency; Step 3: Utilizing… The algorithm performs surface occlusion detection and, based on the independence of the calculation tasks at each incident angle, uses parallel computing to process the scattered light field calculations at multiple angles simultaneously, significantly reducing the computation time.

[0068] 2. Improve model accuracy and applicability, covering computational needs across multiple scenarios. Compared to existing technologies that do not consider energy attenuation during actual propagation and adaptability to various conditions, this invention improves model performance through multi-dimensional optimization: σ obtained in step 5 through the superposition of complex scattering fields sum This integrates the phase information of each element to avoid errors caused by neglecting phase differences in traditional superposition; step 6 introduces radar attenuation correction based on the formula... It simulates the changes in energy with distance and angle during actual propagation, making the calculation results closer to the real scattering scenario; it supports the rapid acquisition of results under different scenarios by changing the wavelength, target material and incident angle using the near-field RCS calculation model, solving the problem of limited applicability of existing models, and can be widely used in terahertz near-field detection scenarios.

[0069] In summary, the modeling method for near-field radar cross-section simulation calculation based on the terahertz frequency band established in this invention considers near-field phase information and radar attenuation, and uses Kirchhoff approximation theory. The algorithm solves the problem that fast calculations cannot be performed in the terahertz frequency band when measuring electrically large targets in the near field. Attached Figure Description

[0070] Figure 1 This is a flowchart of the method of the present invention.

[0071] Figure 2 This is a surface element partitioning diagram of a flat target model with a length of 5cm, a width of 5cm, and a height of 0.5cm.

[0072] Figure 3 This is a surface element partitioning diagram for a cone-shaped target model with a base radius of 0.5cm and a height of 2cm.

[0073] Figure 4 This is a surface element partitioning diagram for a cylindrical target model with a base radius of 2cm and a height of 8cm.

[0074] Figure 5 This is a diagram showing the surface division of a tank target model with a length of 8.3m, a width of 4.2m, and a height of 2.5m.

[0075] Figure 6 This is a graph showing the variation of the scattered light field of a single small surface element with the incident angle.

[0076] Figure 7 The RCS diagram of the flat plate target model at 2THz is shown.

[0077] Figure 8 The RCS diagram of the conical target model at 2THz is shown.

[0078] Figure 9 The RCS diagram of a cylindrical target model at 2THz is shown.

[0079] Figure 10 RCS diagrams of tank target models at 2THz and 10GHz. Detailed Implementation

[0080] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0081] A modeling method for simulating near-field radar cross section calculation based on the terahertz frequency band, such as... Figure 1 As shown, the method includes:

[0082] Step 1: By utilizing the influence of the near field on the 3D target, the 3D model is divided into multiple facets with a subdivision scale of λ / 3. Simultaneously, the relationship between the individual facet Δs and the unit normal vector of the facet is calculated.

[0083] The process of dividing the model based on near-field characteristics and calculating the unit normal vector for each divided surface element includes:

[0084] When the target is within the near-field region of the measuring radar, the target surface is triangularly divided. Based on the side length of each triangular element, i.e., the division scale, the target's side length is uniformly divided to construct several triangular elements to represent the target surface. The division scale is usually chosen as λ / 3, so that for each small triangular element, the boundary distance between the near and far fields is 2λ / 9, all within the far-field region of the measuring radar.

[0085] Based on the three vertices v1, v2, v3 of the small facet obtained by partitioning, we have:

[0086]

[0087] in, It is the vector pointing from vertex v1 to vertex v2. It is the vector pointing from vertex v1 to vertex v3. It is the unit normal vector of the small facet.

[0088] like Figure 2 , 3 Figures 4 and 5 show the target models: a flat plate, a cone, a cylinder, and a tank, respectively. The red arrows in the figures indicate the unit normal vectors and their directions for each facet during the calculation process. Therefore, this model can correctly determine the orientation of the facet normals in the 3D model, providing an accurate model for the next step of facet calculation and facet intersection / occlusion determination.

[0089] Step 2: Using the Kirchhoff approximation theory, solve for the angle between a single small surface element and the unit normal vector of the surface element under different incident directions, i.e., the scattered light field under different incident angles θ. And store the incident angle and scattered light field data;

[0090] Based on the Kirchhoff approximation theory, the scattered light field of a single small surface element under different incident angles is obtained, including:

[0091] Incident light field for:

[0092]

[0093] Where E0 is the amplitude, and k = 2π / λ is the wave number. The distance from the radar to the facet element is given by j, which represents the imaginary unit.

[0094] Based on the Kirchhoff approximation theory, the scattered light field of each small surface element Δs is calculated.

[0095]

[0096] Where a0 is the scattering coefficient and K is the proportionality constant, expressed as: R is the distance between the target center and the receiving point. Indicates phase change, It is the vector along the direction of the unit wave vector of the incident wave.

[0097] As needed, set the incident angle range and step size, calculate the scattered electric field under different incident angles, and record the incident angle and the scattered electric field.

[0098] like Figure 6 The figure shows the variation of the scattered light field of a single small surface element with the incident angle. At 0°, the small surface element is normally incident, and all scattered light returns along the incident direction, resulting in the largest scattered light field. As the angle increases, the direction of the scattered light field becomes the incident direction, and the scattered light field gradually decreases until it reaches 0 after rotating 90°.

[0099] Step 3: Under different incident conditions, determine the incident occlusion of discrete 3D model elements to obtain effective scattering elements, and obtain the scattered light field at the corresponding angle from the stored data by using the angle between the incident light field and the unit normal of the element.

[0100] The basis The algorithm determines whether a ray intersects with a surface element or if a surface element occludes it, and extracts corresponding data from the calculated scattered light field of a single small surface element based on the incident angle, including:

[0101] use The algorithm first checks the intersection of the facet element with the ray. Any point P on the facet element can be represented as:

[0102]

[0103] Where p is the coordinate of point P, and p′ is the coordinate of any point in the small facet element other than point P. It is the unit normal vector of the small facet.

[0104] Let ray 1 represent the light traveling from radar position o along the unit wave vector. Starting from the ray, the equation can be expressed as:

[0105]

[0106] Where t is a variable, if ray 1 intersects the small surface element at point P, t can be solved, i.e.

[0107]

[0108]

[0109] At this point, the range of t is 0 ≤ t ≤ +∞.

[0110] After the intersection judgment, when ray 1 intersects with other facets and the distance is less than the distance of the facet where point P is located, the facet where point P is located is determined to be occluded, that is, the facet where point P is located cannot reflect effectively; conversely, when ray 1 intersects with other facets and the distance is greater than the distance of the facet where point P is located, the facet where point P is located is determined to be unoccluded, that is, the facet where point P is located can reflect effectively.

[0111] After intersecting and occluding small elements, the scattered light field at the corresponding angle is read from the stored data by the angle between the incident light and the normal of the element, thus obtaining...

[0112] The intersecting of surface elements, the determination of surface element occlusion, and the calculation of the scattered light field are all performed independently at each incident angle. Therefore, parallel computing is used to perform intersection, occlusion, and scattering calculations simultaneously at multiple incident angles, enabling rapid calculation of the scattering situation, i.e., the scattered light field at the corresponding angle.

[0113] Step 4: Based on the RCS far-field scattering calculation formula, solve for the scattering cross section Δσ under a single small surface element;

[0114] The RCS-based far-field scattering calculation formula yields the RCS of each surface element, including:

[0115] According to the formula for calculating far-field scattering of RCS:

[0116]

[0117] The RCS formula for a single facet can be obtained as follows:

[0118]

[0119] Where, Δσ n Let R be the RCS of the nth facet. n Let n be the distance between the nth facet and the radar.

[0120] Step 5: Each surface element has its own phase information, and the RCS of the small surface elements are superimposed to obtain the total scattering cross section σ. sum ;

[0121] The phase information of each surface element is introduced, and the RCS of the small surface elements is superimposed to obtain the total scattering cross section σ. sum,include:

[0122] The phase information of each facet element is incorporated into the RCS formula of a single facet element, and the RCS of the facet elements are superimposed to obtain the total scattering cross section:

[0123]

[0124] Where N is the total number of facets.

[0125] Step 6: During the actual scattering process, the radar energy changes within the illumination range, introducing radar attenuation. The entire near-field RCS calculation model σ can be obtained. g ;

[0126] The change in radar energy within the illumination range during the actual scattering process introduces radar attenuation. The entire near-field RCS calculation model σ can be obtained. g ,include:

[0127] Considering that energy will attenuate to some extent during the actual radar illumination propagation process, radar attenuation is introduced. for:

[0128]

[0129] Where P0 is the radar transmit power, α is the attenuation coefficient, and R n Let θ be the distance between the nth facet and the radar. These are the zenith angle and the azimuth angle, respectively.

[0130] The formula for the near-field radar cross section of a target, considering phase superposition and radar propagation attenuation, is:

[0131]

[0132] like Figure 7 , 8 As shown in Figures 9 and 10, simulations were performed on a flat plate target model with dimensions of 5cm × 5cm × 0.5cm, a conical target model with a base radius of 0.5cm and a height of 2cm, a cylindrical target model with a base radius of 2cm and a height of 8cm, and a tank target model with a length of 8.3m, a width of 4.2m, and a height of 2.5m. The material was set to aluminum, and the incident radio frequency was 2THz. Surface element division, ray intersection occlusion judgment, and RCS calculation were performed on each model. Figure 7 In the middle, the irradiation begins from the side of the flat plate, such as... Figure 2As shown in the diagram, the side of the plane will have a certain specular reflection, resulting in a certain peak value. As the angle increases, there is a path difference when the surface elements of the plate are scattered back, which leads to different phases when received, thus reducing the value after the scattering is superimposed. When rotated to 90 degrees, the plate is normally incident, the area of ​​the plate scattering is the largest, the specular reflection is the strongest, and the maximum value is reached. As the angle continues to increase, due to the symmetry of the plate, the RCS will first decrease and then increase, and a peak value will appear when rotated to 180 degrees. Figure 8 In, such as Figure 3 As shown in the diagram, light is incident from the bottom of the cone and rotates upwards along the cone's axis. When the light reaches the bottom of the cone, specular reflection occurs due to the cone's circular surface with a radius of 0.5 cm, resulting in a large RCS peak. As the angle increases, the incident area first decreases, then increases, and then decreases again, leading to a smaller RCS peak. As the light rotates to the tip of the cone, the scattered light field echo is very small due to the tip's characteristics, and the RCS reaches its minimum value. Figure 9 In, such as Figure 4 As shown in the diagram, when the cylinder is incident from 0 degrees, a large RCS value is generated due to specular scattering. As the angle increases, the effective scattering area first decreases and then increases until a large value appears when the cylinder is rotated to 90 degrees. The cylinder has symmetry, and as the angle increases, the RCS first decreases and then increases until a large value appears when the cylinder is rotated to 180 degrees due to specular scattering at the bottom of the cylinder. Figure 10 In, such as Figure 5 As shown in the diagram, at 2THz, incident light from the side of the tank covers a large area, resulting in a large RCS value. Due to the tank's stepped shape, the received scattering decreases and then increases with the angle, reaching a peak at 90 degrees direct incidence on the tank. Continuing to rotate, the other side of the tank exhibits a similar pattern of first decreasing and then increasing RCS, until a large value appears at 180 degrees incidence. Meanwhile... Figure 10 The SBR method was used to obtain the RCS of the tank at 10 GHz. By comparison, it can be seen that the RCS at 2 THz reflects more detailed information about the tank than the RCS at 10 GHz. This is because the terahertz band can perform a more detailed scan of the target surface than microwaves, thus obtaining more echo information.

[0133] In summary, this invention provides a modeling method for simulating near-field radar cross-sections based on the terahertz frequency band, which calculates the scattered light field of a single small surface element at different incident angles based on the Kirchhoff approximation theory. A scattering database was established using the scattering of individual small surface elements. The algorithm performs occlusion detection on surface elements and uses parallel computing based on the independent operation characteristics of surface elements to accelerate the calculation speed. It also proposes radar attenuation correction, which theoretically improves the accuracy of RCS. In fact, this brand-new RCS near-field calculation model solves the problem of fast calculation of electrically large targets in the near-field measurement in the terahertz band. It can achieve fast subdivision and calculation of target surface through this RCS near-field model, which has important theoretical and practical significance.

[0134] The present invention provides a modeling method for near-field radar cross section simulation calculation based on the terahertz frequency band, comprising:

[0135] The surface element partitioning module divides the surface of the target model into triangular surface elements based on near-field characteristics, and calculates the unit normal vector of the surface element based on the vertices of the partitioned surface elements.

[0136] The surface element calculation module calculates the scattered light field of a single small surface element under different incident angles based on the Kirchhoff approximation theory. And store the data;

[0137] The discrete surface element calculation module, based on the surface element calculation module, performs intersection and occlusion judgment on the divided small surface elements and rays, and calculates the scattered light field of the small surface elements according to the incident angle.

[0138] The target radar cross section (RCS) calculation module substitutes the scattered light field of a surface element at different incident angles into the far-field scattering calculation formula to obtain the RCS of a single small surface element. Considering near-field phase information and radar attenuation, the total scattering cross section σ is then obtained using the complex scattering superposition formula for each scattering center of the RCS. sum .

[0139] An electronic device, comprising:

[0140] At least one processor;

[0141] And, a memory communicatively connected to the at least one processor;

[0142] The memory stores instructions that can be executed by the at least one processor, which are executed by the at least one processor to enable the at least one processor to perform a modeling method for near-field radar cross section simulation calculation based on the terahertz band as described above.

[0143] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements a modeling method for near-field radar cross section simulation calculation based on the terahertz band as described above.

[0144] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM (Read-Only Memory), RAM (Random Access Memory), magnetic disks, or optical disks.

[0145] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A modeling method for simulating and calculating the near-field radar cross section based on the terahertz frequency band, characterized in that, The method includes: Step 1, Surface Partitioning and Unit Normal Vector Calculation: Based on the influence of the near field on the 3D target, surface partitioning is performed to obtain multiple small surfaces with a partitioning scale of λ / 3. Simultaneously, the unit normal vector of each small surface is calculated. Step 2: Solve for individual small surface elements under different incident light fields using Kirchhoff approximation theory. With the unit normal vector of the surface element The angle between them, i.e. the scattered light field at different incident angles. And store the incident angle θ and the scattered light field data; Step 3: Under different incident conditions, determine the incident occlusion of discrete three-dimensional target elements to obtain effective scattering elements, and then analyze the incident light field. Normal to the unit of surface The angle is obtained from the stored data to retrieve the scattered light field at the corresponding angle. Step 4: Based on the radar cross section (RCS) far-field scattering calculation formula, solve for the scattering cross section Δσ under a single small surface element; Step 5: Superimpose the radar cross sections (RCS) of the small surface elements to obtain the total radar cross section σ. sum ; Step 6, introduce radar attenuation The calculation model σ of the entire near-field radar cross section (RCS) is obtained. g .

2. The modeling method for simulating and calculating the near-field radar cross section based on the terahertz frequency band according to claim 1, characterized in that, The specific method for step 1 is as follows: When a three-dimensional target is in the near-field region of the measuring radar, the target is triangularly divided into facets. Using the side length of the facet as the division scale, the side length of the target is uniformly divided to construct several facets, which are used to represent the target surface. Based on the three vertices v1, v2, v3 of the small facet obtained by partitioning, we have: in, It is the vector pointing from vertex v1 to vertex v2. It is the vector pointing from vertex v1 to vertex v3. It is the unit normal vector of the small facet.

3. The modeling method for near-field radar cross section simulation calculation based on the terahertz frequency band according to claim 1, characterized in that, The specific method for step 2 is as follows: Incident light field for: Where E0 is the amplitude, and k = 2π / λ is the wave number. The distance from the radar to the facet element is given by j, which represents the imaginary unit. Based on the Kirchhoff approximation theory, the scattered light field of each small surface element Δs is calculated. Where a0 is the scattering coefficient and K is the proportionality constant, expressed as: R is the distance between the target center and the receiving point. Indicates phase change, i is the vector representing the direction of the unit wave vector of the incident wave; Customize the incident angle range and step size, calculate the scattered electric field under different incident angles, and record the incident angle and scattered electric field.

4. The modeling method for near-field radar cross section simulation calculation based on the terahertz frequency band according to claim 1, characterized in that, The specific method for step 3 is as follows: use The Trumbore algorithm first checks the intersection of the facet with the ray. Any point P on the facet can be represented as: Where p is the coordinate of point P, and p′ is the coordinate of any point in the small facet element other than point P. It is the unit normal vector of the small facet. Let ray 1 represent the light traveling from radar position o along the unit wave vector. Starting from the ray, the equation can be expressed as: Where t is a variable, if ray 1 intersects the small surface element at point P, t can be solved, that is: At this point, the range of t is 0 ≤ t ≤ +∞. After the intersection judgment, if ray 1 intersects with other small facets and the distance between them is less than the distance from ray 1 to the small facet where point P is located, the small facet where point P is located is judged to be occluded, that is, the small facet where point P is located cannot reflect effectively; conversely, if ray 1 intersects with other small facets and the distance between them is greater than the distance between ray 1 and the small facet where point P is located, the small facet where point P is located is judged to be unoccluded, that is, the small facet where point P is located can reflect effectively. After intersecting and occluding small facets, the scattered light field at the corresponding angle is read from the stored data by the angle between the incident light and the normal of the facet unit, thus obtaining...

5. The modeling method for near-field radar cross section simulation calculation based on the terahertz frequency band according to claim 1, characterized in that, The specific method for step 4 is as follows: According to the formula for calculating the far-field scattering of radar cross section (RCS): The formula for the radar cross section (RCS) of a single small surface element is: Where, Δσ n Let R be the radar cross section (RCS) of the nth small element. n Let n be the distance between the nth facet and the radar.

6. The modeling method for near-field radar cross section simulation calculation based on the terahertz frequency band according to claim 1, characterized in that, The specific method for step 5 is as follows: The phase information of each facet element is incorporated into the radar cross section (RCS) formula for a single facet element, and the RCS of the facet elements are superimposed to obtain the total radar cross section σ. sum : Where N is the total number of facets.

7. The modeling method for near-field radar cross section simulation calculation based on the terahertz frequency band according to claim 1, characterized in that, The specific method for step 6 is as follows: Based on the actual radar illumination propagation process, energy will attenuate to a certain extent, and radar attenuation will be introduced. for: Where P0 is the radar transmit power, α is the attenuation coefficient, and R n Let θ be the distance between the nth facet and the radar. These are the zenith angle and the azimuth angle, respectively. The formula for the near-field radar cross section of a target, based on phase superposition and radar propagation attenuation, is as follows:

8. A modeling method for simulating near-field radar cross section calculation based on the terahertz frequency band, based on the method described in claims 1 to 7, characterized in that, include: The surface element partitioning module is used in step 1 to partition the surface of the target model into triangular surface elements based on the near-field characteristics, and to calculate the unit normal vector of the surface element based on the vertices of the partitioned surface elements. The surface element calculation module is used in step 2 to calculate the scattered light field of a single small surface element under different incident angles based on the Kirchhoff approximation theory. And store the data; The discrete surface element calculation module is used in step 3. Based on the surface element calculation module, it performs intersection and occlusion judgment on the divided small surface elements and rays, and calculates the scattered light field of the small surface elements according to the incident angle. The target radar cross section (RCS) calculation module is used in steps 4 to 6 to substitute the scattered light field of the surface element under different incident angles into the far-field scattering calculation formula of the RCS, thus obtaining the RCS of a single small surface element. Considering near-field phase information and radar attenuation, the total scattering cross section σ is obtained by using the complex scattering superposition formula of each scattering center of the RCS. sum .

9. An electronic device, characterized in that, include: At least one processor; And, a memory communicatively connected to the at least one processor; The memory stores instructions that can be executed by the at least one processor, which are executed by the at least one processor to enable the at least one processor to perform a modeling method for near-field radar cross section simulation calculation based on the terahertz band as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements a modeling method for near-field radar cross section simulation calculation based on the terahertz frequency band as described in any one of claims 1 to 7.

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