Modeling method and device for combined scattering field of rough surface facing terahertz band

Abstract

The application relates to a modeling method and device for a combined scattering field of a rough surface in a terahertz frequency band. The method comprises the following steps: performing normalization processing on the normal RCS of a single hemisphere, performing fitting characterization on the result, then correcting an approximate formula of the scattering field of the hemisphere by using the normalized RCS, solving the scattering field of a larger radius hemisphere, constructing a phase factor of the scattering field of the hemisphere at different positions by using the relative position relationship of the hemisphere, deducing a scattering field expression of a hemisphere array based on a vector superposition principle, determining the energy ratio of non-coherent scattering field and coherent scattering field according to the ratio of the area of the planar element covered by the hemisphere to the area of the planar element not covered by the hemisphere, performing vector superposition on the scattering field of the hemisphere array and the scattering field of a smooth flat plate based on the superposition idea of non-coherent and coherent scattering, and solving the scattering field of the hemisphere-flat plate combination after the normal RCS of the hemisphere-flat plate combination is corrected. The method can improve the modeling efficiency of the rough surface in the terahertz frequency band.

Description

Technical Field

[0001] This application relates to the field of terahertz rough surface modeling technology, and in particular to a method and apparatus for modeling the scattering field of a combined rough surface in the terahertz band. Background Technology

[0002] Terahertz waves typically refer to electromagnetic waves with frequencies between 0.1 THz and 10 THz. Compared to microwaves, terahertz waves have shorter wavelengths, placing them on the same order of magnitude as the fine structures of target surfaces. Terahertz waves are sensitive to the fine structures and roughness of target surfaces. Research on the scattering characteristics of targets in the terahertz band needs to consider the influence of surface roughness fluctuations, requiring characterization of these fluctuations in target scattering modeling. There are various methods for characterizing the fluctuations of rough surfaces. A widely used method is to simulate surface roughness fluctuations through stochastic processes. Based on this, a series of approximate calculation methods for electromagnetic scattering of rough surfaces have been developed, such as the Kirchhoff approximation method, the perturbation method, the dual-scale approximation method combining large and small scales, and the rough surface approximation method based on integral equations. These methods are mostly used for electromagnetic scattering modeling calculations of random rough surfaces in natural environments (such as land and sea surfaces). They mainly rely on macroscopic roughness parameters for modeling calculations, focusing on characterizing the distribution of scattered energy, but lacking the ability to depict fine structures. As the frequency increases to the terahertz band, the electrical size of the target increases, and the number of surface elements for constructing rough surfaces increases dramatically. Current research on the scattering characteristics of rough targets in the terahertz band suffers from high modeling complexity and low computational efficiency.

[0003] In addition to the method of generating rough surfaces using stochastic processes, the simulation of rough surface undulations can also be achieved by constructing a randomly distributed hemispherical array for equivalent characterization. Compared to constructing rough surfaces using stochastic processes, the hemispherical model can characterize incoherent scattering, improving the accuracy of modeling the scattering characteristics of electrically large rough surfaces in the terahertz band. This provides a high-precision model for studying the scattering characteristics of rough targets in the terahertz band and, to some extent, improves the efficiency of modeling and computation. V. Twersky studied the scattering characteristics of rough surfaces based on the hemispherical model and derived the calculation formula for the scattering field of the hemispherical array model under specific distribution parameter conditions. However, the hemispherical model scattering field calculation formula proposed by V. Twersky is not applicable to the undulation characteristics of rough surfaces in the current terahertz band. Therefore, it is necessary to construct a corresponding hemispherical model based on the undulation characteristics of rough surfaces in the terahertz band and propose corresponding calculation methods for the scattering field of the hemispherical array and the scattering field of the hemispherical-plate combination.

[0004] However, there are currently few methods for modeling the scattering characteristics of rough surfaces in the terahertz band. Existing modeling and calculation methods based on macroscopic roughness parameters cannot accurately characterize the roughness fluctuations of the model, and the amount of information provided is insufficient to support the needs of scaled-down inversion and refined detection imaging. Furthermore, due to the dramatic increase in the number of surface elements of electrically large rough surfaces in the terahertz band, existing methods are time-consuming for modeling and calculation. Existing hemispherical roughness models in the microwave band can only calculate the scattering field of the hemispherical array within a small range of parameters, which cannot meet the needs of modeling and calculating rough surfaces in the terahertz band. Summary of the Invention

[0005] Therefore, it is necessary to provide a combined scattering field method and apparatus for terahertz rough surfaces that can improve the modeling efficiency of rough surfaces in the terahertz band, in order to address the above-mentioned technical problems.

[0006] A combined volume scattering field method for rough surfaces in the terahertz band, the method comprising:

[0007] Obtain the normal RCS of hemispheres with different radii;

[0008] The normal RCS of the plane elements covered by hemispheres of different radii is derived by the surface element integral method. The normalized RCS of the hemisphere is then normalized using the normalized RCS of the plane elements covered by the hemisphere to obtain the normalized curve of the normalized RCS of the hemisphere.

[0009] The normalized curve of the hemispherical normal RCS is fitted to obtain the fitted value;

[0010] The approximate value of the scattering field of a single hemisphere is corrected based on the fitted value to obtain the corrected hemisphere scattering field;

[0011] The relative positions of the hemispheres and the corrected hemispherical scattering field are used to construct a hemispherical array scattering field composed of multiple randomly distributed hemispheres;

[0012] The ratio of the area of ​​all hemispherical planes covered by the hemispherical array to the area of ​​the plate in the assembly is calculated based on the distribution parameters of the hemispherical array and the size of the plate. The energy ratio of the incoherent and coherent scattered fields is determined by the ratio of the areas. The normal RCS of the hemispherical-plate assembly is then calculated using the area ratio.

[0013] The scattered field of the hemispherical array and the scattered field of the smooth plate are vector superimposed according to the superposition method of incoherent and coherent scattering. After correction by the normal RCS of the hemispherical-plate combination, the scattered field of the hemispherical-plate combination is obtained.

[0014] In one embodiment, the normalized RCS of the hemisphere is normalized using the normal RCS of the planar elements covered by the hemisphere, resulting in a normalized curve of the hemisphere's normal RCS, including:

[0015] The normalized RCS of the hemisphere is obtained by normalizing the RCS of the plane elements covered by the hemisphere.

[0016]

[0017] Where, σ q覆盖面元 (a q ,0°)=k 2 ·(S q覆盖面元 ) 2 / π represents a radius of a q The plane element covered by the hemisphere at the normal angle The corresponding RCS value, wavenumber k = 2π / λ, σ represents the area of ​​the surface element covered by the hemisphere. q半球 (a q ,0°) represents a radius of a q The hemisphere at the normal angle The corresponding RCS value.

[0018] In one embodiment, the normalized curve of the hemispherical normal RCS is fitted to obtain a fitted value, including:

[0019] The normalized curve of the hemispherical normal RCS is fitted to obtain the fitted value.

[0020] f(ka)=y0+C·exp(-exp(-(ka-x0) / w)-(ka-x0) / w+1)

[0021] Where y0, C, x0, and w are parameters to be determined, and ka represents the electrical dimension of the hemisphere.

[0022] In one embodiment, the approximation of a single hemispherical scattering field is corrected based on the fitted value to obtain a corrected hemispherical scattering field, including:

[0023] The approximate value of the scattering field of a single hemisphere is corrected based on the fitted value to obtain the corrected approximate value of the scattering field of the hemisphere.

[0024]

[0025] Where r represents the distance from the observation point to the hemisphere, A and B represent the amplitudes of different polarization components, and θ0 represents the unit vector in the θ direction in the spherical coordinate system. In spherical coordinates The unit vector of direction, where α represents the angle between the incident wave vector and the z-axis, and θ represents the angle between the observation direction vector and the z-axis. This represents the angle between the projection of the observation direction vector onto the XOY plane and the x-axis;

[0026] The corrected approximation of the hemispherical scattering field is derived, resulting in the corrected hemispherical scattering field as follows:

[0027]

[0028] In one embodiment, the scattering field of a hemispherical array composed of multiple randomly distributed hemispheres is constructed using the relative positional relationship of the hemispheres and the corrected hemispherical scattering field, including:

[0029] The scattering field of a hemispherical array composed of multiple randomly distributed hemispheres is constructed using the relative positions of the hemispheres and the corrected hemispherical scattering field.

[0030]

[0031] Among them, K i =kn i = -k(sinαi0+cosαk0), r p =x p i0+y p j0, where the subscript p represents hemispheres at different positions and with different radii, and N represents the total number of hemispheres.

[0032] In one embodiment, the normal RCS of the hemispherical-plate assembly is calculated using the area ratio, including:

[0033] The normal RCS of the hemispherical-plate assembly was calculated using the area ratio.

[0034]

[0035] Among them, a mean This represents the mean radius of the hemispherical array. σ represents the ratio of the area of ​​the plane covered by all hemispheres to the area of ​​the flat plate in the composite structure. 光滑平板 (0°) represents the normal RCS value corresponding to a smooth flat plate.

[0036] In one embodiment, the scattered field of the hemispherical array and the scattered field of the smooth plate are vector-superimposed according to the incoherent and coherent scattering superposition method. After correction by the RCS of the hemispherical-plate combination, the scattered field of the hemispherical-plate combination is obtained, including:

[0037] The scattered field from the hemispherical array and the scattered field from the smooth plate are vector-superimposed using the incoherent and coherent scattering superposition method. After correction for the RCS of the hemispherical-plate combination, the scattered field of the hemispherical-plate combination is obtained as follows:

[0038]

[0039] Among them, E plate sE represents the scattering field of a smooth flat plate. s (0°) represents the normal scattering field of the hemispherical array, E plate s (0°) represents the normal scattering field of a smooth flat plate.

[0040] A combined scattering field modeling device for rough surfaces in the terahertz band, the device comprising:

[0041] The normalization module is used to obtain the normal RCS of hemispheres with different radii; it derives the normal RCS of the plane elements covered by hemispheres with different radii based on the surface element integral method, and normalizes the normal RCS of the hemispheres using the normal RCS of the plane elements covered by the hemispheres to obtain the normalized curve of the normal RCS of the hemispheres.

[0042] The fitting correction module is used to fit the normalized curve of the hemispherical normal RCS to obtain the fitted value; and to correct the approximate value of the individual hemispherical scattering field based on the fitted value to obtain the corrected hemispherical scattering field.

[0043] The hemispherical array scattering field module is used to construct a hemispherical array scattering field composed of multiple randomly distributed hemispheres by utilizing the relative positional relationship of the hemispheres and the corrected hemispherical scattering field.

[0044] The module for calculating the normal RCS of the combined structure is used to calculate the ratio of the area of ​​all hemispherical planes covered by the hemispherical array to the area of ​​the plate in the combined structure based on the distribution parameters of the hemispherical array and the size of the plate, to determine the energy ratio of the incoherent and coherent scattered fields, and to calculate the normal RCS of the hemispherical-plate combined structure using the area ratio.

[0045] The module for calculating the scattering field of the combined object is used to vector superimpose the scattering field of the hemispherical array and the scattering field of the smooth plate according to the superposition method of incoherent and coherent scattering. After correction by the RCS of the hemispherical-plate combination, the scattering field of the hemispherical-plate combination is obtained.

[0046] The aforementioned method and apparatus for modeling the scattered field of a combined rough surface in the terahertz band first normalizes the normal RCS of a single hemisphere and fits the result to obtain the trend of the hemisphere's RCS with radius. Then, the approximate formula for the hemispherical scattered field is corrected using the normalized RCS and applied to solve the scattered field of hemispheres with larger radii. This enables rapid calculation of the scattered field of hemispheres with larger radii and hemispherical arrays, expanding the applicability of the hemispherical scattered field formula and meeting the parameter requirements of terahertz band hemispherical array models. Furthermore, the phase factor of the scattered field at different hemisphere positions is constructed using the relative positional relationship of the hemispheres, based on the principle of vector superposition. The scattering field expression of the hemispherical array is derived, enabling the modeling and characterization of the contribution of incoherent scattering, which is beneficial for subsequent calculation of the scattering field of the combined system. Then, based on the ratio of the area of ​​the plane elements covered by the hemisphere to the area of ​​the uncovered plane elements, the energy ratio of the incoherent and coherent scattering fields is determined. Based on the idea of ​​superimposing coherent and incoherent scattering, the scattering field of the hemispherical array is vector-superimposed with the scattering field of the smooth plate. After correction by the RCS of the hemispherical-plate combination, the scattering field of the hemispherical-plate combination is obtained, realizing the modeling and calculation of the scattering field of the hemispherical-plate combination in the terahertz band, providing an efficient method for modeling and calculating the scattering characteristics of rough surfaces. Attached Figure Description

[0047] Figure 1 This is a flowchart illustrating a method for modeling the scattering field of a combined volume for rough surfaces in the terahertz band, as described in one embodiment.

[0048] Figure 2 This is a schematic diagram of the process for solving the scattering field of a hemispherical-plate combination in one embodiment;

[0049] Figure 3 This is a schematic diagram of the hemispherical scattering field in one embodiment;

[0050] Figure 4 This is a schematic diagram of a simulation scenario of a hemispherical-flat plate assembly in another embodiment;

[0051] Figure 5 Here are schematic diagrams of the RCS calculation results for a hemispherical-plate combination with different distribution parameters in one embodiment; (a) is a schematic diagram of the calculation results when the mean radius is 0.29λ, (b) is a schematic diagram of the calculation results when the mean radius is 0.37λ, and (c) is a schematic diagram of the calculation results when the mean radius is 0.5λ.

[0052] Figure 6 This is a structural block diagram of a combined scattering field modeling device for a rough surface in the terahertz band, as shown in one embodiment. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0054] In one embodiment, such as Figure 1 and Figure 2 As shown, a combined volume scattering field method for rough surfaces in the terahertz band is provided, including the following steps:

[0055] Step 102: Obtain the normal RCS of hemispheres with different radii; derive the normal RCS of the planar elements covered by hemispheres with different radii using the surface element integral method; normalize the normal RCS of the hemispheres using the normal RCS of the planar elements covered by the hemispheres to obtain the normalized curve of the normal RCS of the hemispheres.

[0056] First, the scattering fields of hemispheres with different radii are obtained through simulation calculations, with corresponding geometric scenes as follows: Figure 3 As shown. The parameter range of the hemispherical model targeted by this invention is as follows: the radii of the hemispheres constituting the hemispherical array follow a Gaussian distribution, with a mean radius a. mean The range of values ​​is Standard deviation of radius a std The range of values ​​for is a std <0.2λ, the mean b of the hemispherical distribution interval mean Range of values ​​b mean >λ;

[0057] The normalization method proposed in this application is the foundation and key to the entire invention. Based on the formula for solving the scattering field of a surface element using the surface element integral method, the scattering field corresponding to the planar surface element covered by the hemisphere can be derived. Furthermore, its corresponding normal RCS is obtained, and the normal RCS of the corresponding hemisphere is normalized using the normal RCS of this planar surface element. This yields the trend of the hemisphere's RCS changing with its radius. This normalization result can not only characterize the RCS of a single hemisphere with respect to its radius, but also, within a certain parameter range, can be used to characterize the trend of the normal RCS of a randomly distributed hemispherical array with respect to the mean radius of the hemispherical array, providing a normalized characterization model for studying the scattering characteristics of different hemispherical arrays.

[0058] The normalized hemispherical normal RCS model is used to solve the scattering field of the hemisphere and the hemispherical array, which expands the applicable range of hemispherical parameters and breaks through the limitation of the hemispherical radius on the approximate formula of the hemispherical scattering field, so that the hemispherical model can meet the requirements of modeling the scattering characteristics of rough surfaces in the terahertz band.

[0059] Step 104: Fit the normalized curve of the hemispherical normal RCS to obtain the fitted value; correct the approximate value of the single hemispherical scattering field based on the fitted value to obtain the corrected hemispherical scattering field.

[0060] By fitting the normalized RCS curve of the hemispherical normal and using the normalization results to correct the approximate scattering field of hemispheres with different radii, it is possible to quickly calculate the scattering field of hemispheres with larger radii and hemispherical arrays, thus meeting the parameter requirements of hemispherical array models in the terahertz band.

[0061] Step 106: Construct a hemispherical array scattering field composed of multiple randomly distributed hemispheres using the relative positional relationship of the hemispheres and the corrected hemispherical scattering field.

[0062] By utilizing the relative positions of the hemispheres, phase factors of the scattered fields at different hemisphere positions are constructed. Based on the principle of vector superposition, the expression for the scattered field of the hemisphere array is derived, realizing the modeling and characterization of the contribution of incoherent scattering, which is beneficial for subsequent calculation of the scattered field of the combined body.

[0063] Step 108: Calculate the ratio of the area of ​​all hemispherical-covered planes to the area of ​​the plate in the assembly based on the distribution parameters of the hemispherical array and the size of the plate. Determine the energy ratio of the incoherent and coherent scattered fields. Calculate the normal RCS value of the hemispherical-plate assembly using the area ratio.

[0064] Step 110: The scattered field of the hemispherical array and the scattered field of the smooth plate are vector superimposed according to the incoherent and coherent scattering superposition method. After the normal RCS of the hemispherical-plate combination is corrected, the scattered field of the hemispherical-plate combination is obtained.

[0065] The scattering field of the hemispherical-plate assembly is considered to consist of two parts: coherent scattering and incoherent scattering. The energy ratio of the incoherent and coherent scattering fields is determined based on the ratio of the area of ​​the plane covered by the hemispherical assembly to the area of ​​the plate in the assembly. The scattering field of the hemispherical-plate assembly is obtained based on the idea of ​​superimposing coherent and incoherent scattering. This application obtains the scattering field of the hemispherical-plate assembly based on the idea of ​​superimposing coherent and incoherent scattering, realizes the modeling and calculation of the scattering characteristics of the hemispherical-plate assembly in the terahertz band, provides an efficient method for modeling and calculating the scattering characteristics of rough surfaces, and also provides a high-precision scattering characteristic characterization model for RCS scaling and inversion, and refined imaging detection of rough targets in the terahertz band.

[0066] In the aforementioned modeling method for the combined scattering field of rough surfaces in the terahertz band, the normal RCS of a single hemisphere is first normalized and the result is fitted to characterize it, revealing the variation trend of the hemisphere's RCS with its radius. Then, the approximate formula for the hemisphere's scattering field is corrected using the normalized RCS and applied to solve for the scattering field of hemispheres with larger radii. This enables rapid calculation of the scattering field of hemispheres with larger radii and hemisphere arrays, expanding the applicability of the hemisphere scattering field formula and meeting the parameter requirements of terahertz band hemisphere array models. Furthermore, the phase factor of the scattering field at different hemisphere positions is constructed using the relative positional relationship of the hemispheres, and the model is derived based on the principle of vector superposition. The scattering field expression of the hemispherical array is derived to model and characterize the contribution of incoherent scattering, which is beneficial for subsequent calculation of the scattering field of the combined system. Then, based on the ratio of the area of ​​the plane elements covered by the hemisphere to the area of ​​the uncovered plane elements, the energy ratio of the coherent and incoherent scattering fields is determined. Based on the idea of ​​superimposing coherent and incoherent scattering, the scattering field of the hemispherical array is vector-superimposed with the scattering field of the smooth plate. After correction by the RCS of the hemispherical-plate combination, the scattering field of the hemispherical-plate combination is obtained, realizing the modeling and calculation of the scattering field of the hemispherical-plate combination in the terahertz band, providing an efficient method for modeling and calculating the scattering characteristics of rough surfaces.

[0067] In one embodiment, the normalized RCS of the hemisphere is normalized using the normal RCS of the planar elements covered by the hemisphere, resulting in a normalized curve of the hemisphere's normal RCS, including:

[0068] The normalized RCS of the hemisphere is obtained by normalizing the RCS of the plane elements covered by the hemisphere.

[0069]

[0070] Where, σ q覆盖面元 (a q ,0°)=k 2 ·(S q覆盖面元 ) 2 / π represents a radius of a q The plane element covered by the hemisphere at the normal angle The corresponding RCS value, wavenumber k = 2π / λ, σ represents the area of ​​the surface element covered by the hemisphere. q半球 (a q ,0°) represents a radius of a q The hemisphere at the normal angle The corresponding RCS value.

[0071] In one embodiment, the normalized curve of the hemispherical normal RCS is fitted to obtain a fitted value, including:

[0072] The normalized curve of the hemispherical normal RCS is fitted to obtain the fitted value.

[0073] f(ka)=y0+C·exp(-exp(-(ka-x0) / w)-(ka-x0) / w+1)

[0074] Where y0, C, x0, and w are parameters to be determined, and ka represents the electrical dimension of the hemisphere.

[0075] In one embodiment, the approximation of a single hemispherical scattering field is corrected based on the fitted value to obtain a corrected hemispherical scattering field, including:

[0076] The approximate value of the scattering field of a single hemisphere is corrected based on the fitted value to obtain the corrected approximate value of the scattering field of the hemisphere.

[0077]

[0078] Where r represents the distance from the observation point to the hemisphere, A and B represent the amplitudes of different polarization components, and θ0 represents the unit vector in the θ direction in the spherical coordinate system. In spherical coordinates The unit vector of direction, where α represents the angle between the incident wave vector and the z-axis, and θ represents the angle between the observation direction vector and the z-axis. This represents the angle between the projection of the observation direction vector onto the XOY plane and the x-axis;

[0079] The corrected approximation of the hemispherical scattering field is derived, resulting in the corrected hemispherical scattering field as follows:

[0080]

[0081] In one embodiment, the scattering field of a hemispherical array composed of multiple randomly distributed hemispheres is constructed using the relative positional relationship of the hemispheres and the corrected hemispherical scattering field, including:

[0082] The scattering field of a hemispherical array composed of multiple randomly distributed hemispheres is constructed using the relative positions of the hemispheres and the corrected hemispherical scattering field.

[0083]

[0084] Among them, K i =kn i = -k(sinαi0+cosαk0), r p =x p i0+y p j0, where the subscript p represents hemispheres at different positions and with different radii, and N represents the total number of hemispheres.

[0085] In one embodiment, the normal RCS of the hemispherical-plate assembly is calculated using the area ratio, including:

[0086] The normal RCS of the hemispherical-plate assembly was calculated using the area ratio.

[0087]

[0088] Among them, a mean This represents the mean radius of the hemispherical array. σ represents the ratio of the area of ​​the plane covered by all hemispheres to the area of ​​the flat plate in the composite structure. 光滑平板 (0°) represents the normal RCS value corresponding to a smooth flat plate.

[0089] In a specific embodiment, for a particular hemispherical-plate assembly, based on the hemispherical array distribution parameters (mean radius a) mean Given the number of hemispheres (N) and the dimensions of the plate, we can obtain the ratio of the area of ​​the plane covered by all the hemispheres to the area of ​​the plate in the assembly. Determine the energy ratio between the incoherent and coherent scattered fields.

[0090] In one embodiment, the scattered field of the hemispherical array and the scattered field of the smooth plate are vector-superimposed according to the incoherent and coherent scattering superposition method. After correction by the RCS of the hemispherical-plate combination, the scattered field of the hemispherical-plate combination is obtained, including:

[0091] The scattered field from the hemispherical array and the scattered field from the smooth plate are vector-superimposed using the incoherent and coherent scattering superposition method. After correction for the RCS of the hemispherical-plate combination, the scattered field of the hemispherical-plate combination is obtained as follows:

[0092]

[0093] Among them, E plate s E represents the scattering field of a smooth flat plate. s (0°) represents the normal scattering field of the hemispherical array, E plate s (0°) represents the normal scattering field of a smooth flat plate.

[0094] In a specific embodiment, to demonstrate the effectiveness of the method, corresponding simulation experiments were conducted, the details of which are as follows. Within a specific range of hemispherical parameters, hemispherical-plate combination models with different parameters were designed, and the simulation scenarios are as follows. Figure 4 As shown, the hemisphere and the plate are located in the XOY plane, and the incident wave is located in the XOZ plane. The RCS of the corresponding models were calculated using simulation software and the method proposed in this invention. The relevant parameters for modeling and calculating the hemisphere-plate combination are listed in Table 1.

[0095] Table 1

[0096]

[0097] The calculated RCS results for hemispherical-plate assemblies with different distribution parameters are as follows: Figure 5 As shown, by comparing the calculation results of the proposed method with those of the simulation software, it can be seen that within the normal range of 30°, the proposed method has high accuracy in calculating the combined body. As the mean of the hemisphere increases, the angle range for high-precision calculation by the proposed method decreases, and the error of the non-mirror angle gradually increases. When the mean radius reaches 0.5λ, under the condition that the distribution interval is greater than the wavelength λ, the calculation error of the normal is less than 3dB. This shows that within a certain range of hemisphere distribution parameters, the proposed method can perform high-precision modeling and calculation of the RCS of the hemisphere-plate combination, proving the effectiveness of the method in this application.

[0098] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0099] In one embodiment, such as Figure 6 As shown, a device for modeling the scattering field of a combined surface with rough surfaces in the terahertz band is provided, including: a normalization processing module 602, a fitting correction module 604, a hemispherical array scattering field module 606, a combined surface normal RCS value calculation module 608, and a combined surface scattering field calculation module 610, wherein:

[0100] The normalization processing module 602 is used to obtain the normal RCS of hemispheres with different radii; the normal RCS of the plane elements covered by hemispheres with different radii is derived according to the surface element integral method, and the normalization processing of the normal RCS of the hemispheres is performed using the normal RCS of the plane elements covered by the hemispheres to obtain the normalized curve of the normal RCS of the hemispheres.

[0101] The fitting correction module 604 is used to fit the normalized curve of the hemispherical normal RCS to obtain the fitted value; and to correct the approximate value of the single hemispherical scattering field based on the fitted value to obtain the corrected hemispherical scattering field.

[0102] The hemispherical array scattering field module 606 is used to construct a hemispherical array scattering field composed of multiple randomly distributed hemispheres by utilizing the relative positional relationship of the hemispheres and the corrected hemispherical scattering field.

[0103] The combined normal RCS calculation module 608 is used to calculate the ratio of the area of ​​all hemispherical covered planes to the area of ​​the plate in the combined structure based on the distribution parameters of the hemispherical array and the size of the plate, to determine the energy ratio of the incoherent and coherent scattered fields, and to calculate the normal RCS of the hemispherical-plate combined structure using the area ratio.

[0104] The combined scattering field calculation module 610 is used to vector superimpose the scattering field of the hemispherical array and the scattering field of the smooth plate according to the incoherent and coherent scattering superposition methods, and obtain the scattering field of the hemispherical-plate combination after RCS correction of the normal direction of the hemispherical-plate combination.

[0105] Specific limitations regarding the combined scattering field modeling device for terahertz rough surfaces can be found in the limitations of the combined scattering field modeling method for terahertz rough surfaces described above, and will not be repeated here. Each module in the aforementioned combined scattering field modeling device for terahertz rough surfaces can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0106] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for modeling the scattering field of a combined volume of rough surfaces in the terahertz frequency band, characterized in that, The method includes: Obtain the normal RCS of hemispheres with different radii; The normal RCS of the planar surface elements covered by hemispheres of different radii is derived using the surface element integral method. The normalized RCS of the hemisphere is then normalized using the normalized RCS of the planar surface elements covered by the hemisphere to obtain the normalized curve of the normalized RCS of the hemisphere. The normalized curve of the hemispherical normal RCS is fitted to obtain the fitted value; The approximate value of the single hemispherical scattering field is corrected based on the fitted value to obtain the corrected hemispherical scattering field; The relative positions of the hemispheres and the corrected hemispherical scattering field are used to construct a hemispherical array scattering field composed of multiple randomly distributed hemispheres; The ratio of the area of ​​all hemispherical-covered planes to the area of ​​the plate in the assembly is calculated based on the distribution parameters of the hemispherical array and the size of the plate. The energy ratio of the incoherent and coherent scattered fields is then determined, and the normal RCS of the hemispherical-plate assembly is calculated using the area ratio. The scattered field of the hemispherical array and the scattered field of the smooth plate are vector superimposed according to the incoherent and coherent scattering superposition method. After the normal RCS of the hemispherical-plate combination is corrected, the scattered field of the hemispherical-plate combination is obtained.

2. The method according to claim 1, characterized in that, The normalized RCS of the hemisphere is obtained by normalizing the RCS of the plane elements covered by the hemisphere, resulting in a normalized curve of the hemisphere's normal RCS, including: The normalized RCS of the hemisphere is obtained by normalizing the RCS of the plane elements covered by the hemisphere. Where, σ q覆盖面元 (a q ,0°)=k 2 ·(S q覆盖面元 ) 2 / π represents a radius of a q The plane element covered by the hemisphere at the normal angle The corresponding RCS value, wavenumber k = 2π / λ, σ represents the area of ​​the surface element covered by the hemisphere. q半球 (a q ,0°) represents a radius of a q The hemisphere at the normal angle The corresponding RCS value.

3. The method according to claim 2, characterized in that, The normalized curve of the hemispherical normal RCS is fitted to obtain the fitted value, including: The normalized curve of the hemispherical normal RCS is fitted to obtain the fitted value. f(ka)=y0+C·exp(-exp(-(ka-x0) / w)-(ka-x0) / w+1) Where y0, C, x0, and w are parameters to be determined, and ka represents the electrical dimension of the hemisphere.

4. The method according to claim 3, characterized in that, The approximate value of the single hemispherical scattering field is corrected based on the fitted value to obtain the corrected hemispherical scattering field, including: The approximate value of the scattering field of a single hemisphere is corrected based on the fitted value to obtain the corrected approximate value of the scattering field of the hemisphere. Where r represents the distance from the observation point to the hemisphere, A and B represent the amplitudes of different polarization components, and θ0 represents the unit vector in the θ direction in the spherical coordinate system. In spherical coordinates The unit vector of direction, where α represents the angle between the incident wave vector and the z-axis, and θ represents the angle between the observation direction vector and the z-axis. This represents the angle between the projection of the observation direction vector onto the XOY plane and the x-axis; The corrected hemispherical scattering field approximation is derived to obtain the corrected hemispherical scattering field as follows:

5. The method according to claim 4, characterized in that, The scattering field of a hemispherical array composed of multiple randomly distributed hemispheres is constructed using the relative positions of the hemispheres and the corrected hemispherical scattering field, including: The scattering field of a hemispherical array composed of multiple randomly distributed hemispheres is constructed using the relative positions of the hemispheres and the corrected hemispherical scattering field. Among them, K i =kn i = -k(sinαi0+cosαk0), r p =x p i0+y p j0, where the subscript p represents hemispheres at different positions and with different radii, and N represents the total number of hemispheres.

6. The method according to claim 3, characterized in that, The normal RCS of the hemispherical-plate assembly is calculated using the area ratio, including: The normal RCS of the hemispherical-plate assembly was calculated using the area ratio. Among them, a mean This represents the mean radius of the hemispherical array. σ represents the ratio of the area of ​​the plane covered by all hemispheres to the area of ​​the flat plate in the composite structure. 光滑平板 (0°) represents the normal RCS value corresponding to a smooth flat plate.

7. The method according to claim 6, characterized in that, The scattered field of the hemispherical array and the scattered field of the smooth plate are vector-superimposed according to the incoherent and coherent scattering superposition method. After correction by the RCS of the hemispherical-plate combination, the scattered field of the hemispherical-plate combination is obtained, including: The scattered field of the hemispherical array and the scattered field of the smooth plate are vector-superimposed using the incoherent and coherent scattering superposition method. After correction by the RCS of the hemispherical-plate combination, the scattered field of the hemispherical-plate combination is obtained as follows: Among them, E plate s E represents the scattering field of a smooth flat plate. s (0°) represents the normal scattering field of the hemispherical array, E plate s (0°) represents the normal scattering field of a smooth flat plate.

8. A combined scattering field modeling device for rough surfaces in the terahertz band, characterized in that, The device includes: The normalization module is used to obtain the normal RCS of hemispheres with different radii; it derives the normal RCS of the plane elements covered by hemispheres with different radii based on the surface element integral method, and normalizes the normal RCS of the hemispheres using the normal RCS of the plane elements covered by the hemispheres to obtain the normalized curve of the normal RCS of the hemispheres. The fitting correction module is used to fit the normalized curve of the hemispherical normal RCS to obtain the fitting value; and to correct the approximate value of the single hemispherical scattering field based on the fitting value to obtain the corrected hemispherical scattering field. The hemispherical array scattering field module is used to construct a hemispherical array scattering field composed of multiple randomly distributed hemispheres by utilizing the relative positional relationship of the hemispheres and the corrected hemispherical scattering field. The combined normal RCS calculation module is used to calculate the ratio of the area of ​​all hemisphere-covered planes to the area of ​​the plate in the combined structure based on the distribution parameters of the hemispherical array and the size of the plate, to determine the energy ratio of the incoherent and coherent scattered fields, and to calculate the normal RCS of the hemispherical-plate combined structure using the area ratio. The combined scattering field calculation module is used to vector superimpose the scattering field of the hemispherical array and the scattering field of the smooth plate according to the incoherent and coherent scattering superposition method, and obtain the scattering field of the hemispherical-plate combination after correction by the normal RCS of the hemispherical-plate combination.

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