A method for calculating electromagnetic scattering from foil clouds based on the volume element method.

Abstract

This invention discloses a method for calculating electromagnetic scattering of chaff clouds based on the volume element method, belonging to the field of chaff electromagnetic scattering technology. The method divides a three-dimensional chaff cloud into multiple volume element regions, calculates the scattering field value of each region, and then combines the inter-region shielding effect and attenuation coefficient to obtain the actual scattering field value of the entire chaff cloud. The proposed method can more accurately simulate the electromagnetic scattering characteristics of chaff clouds under electromagnetic wave irradiation, and has significant application value in fields such as electronic warfare.

Description

Technical Field

[0001] This invention relates to the field of foil electromagnetic scattering technology, and in particular to a method for calculating electromagnetic scattering of foil clouds based on the volume element method. Background Art

[0002] Chalcoat, as the most widely used passive jamming material, plays an extremely important role in electronic warfare due to its simple manufacturing, convenient use, and significant effects. In order to fully utilize the jamming effect of chaff in electronic warfare applications, it is urgent to understand its related characteristics such as motion diffusion, electromagnetic scattering, and radio wave propagation in the atmosphere. Therefore, the study of motion diffusion models and electromagnetic scattering characteristics of chaff clouds has gradually become the research object of researchers engaged in target characteristic research at home and abroad.

[0003] Current methods for calculating electromagnetic scattering from chaff clouds often employ simplified models that neglect the coupling and shielding effects between the chaff strips, as well as the blocking effects between different regions within the cloud. This leads to significant discrepancies between the calculated results and actual electromagnetic scattering characteristics. Therefore, it is necessary to propose a more efficient and accurate method for calculating electromagnetic scattering from chaff clouds to more accurately simulate their electromagnetic scattering properties. Summary of the Invention

[0004] This invention proposes a method for calculating electromagnetic scattering of chaff clouds based on the volume element method. The method uses the volume element method to divide the chaff cloud into multiple volume element regions and considers the chaff concentration and attenuation coefficient of each region to accurately calculate the scattering field of the entire chaff cloud, thereby achieving efficient and accurate electromagnetic scattering calculation of chaff clouds.

[0005] The technical solution adopted in this invention is as follows:

[0006] A method for calculating electromagnetic scattering from chaff clouds based on the volume element method, comprising the following steps:

[0007] Step 1, construct different foil concentrations ρ per unit volume A With scattered field statistics A one-to-one correspondence of foil concentration scattering field mapping table;

[0008] Step 2: Use the voxel segmentation method to uniformly divide the foil cloud model into multiple voxels (i.e., each voxel is a foil cloud voxel), and count the number of foil strips m in each voxel region. j Based on m j The cumulative value of the foil concentration is used to obtain the foil concentration ρ of the volume element;

[0009] Find the scattering field statistics of the foil concentration ρ for each volume element in the foil concentration scattering field mapping table. And Multiplying by the volume of the volume element yields the scattering field of a single volume element.

[0010] Step 3, set the attenuation coefficient α for each volume element. j The attenuation coefficient α j The path depth d of the electromagnetic wave incident on the current volume element in the direction of the incoming wave. j Positive correlation;

[0011] Step 4, scatter the field of each volume element With attenuation coefficient α j Multiplying yields the actual scattered field of each volume element.

[0012] Step 5: Actual scattering field of all volume elements based on the chaff cloud model The summation yields the total scattering field value of the foil cloud.

[0013] Furthermore, in step 1, when constructing the foil concentration scattering field mapping table, the scattering field statistics are calculated as follows:

[0014] Without considering the coupling and shielding effects between the foils, electromagnetic scattering calculations were performed on foil clouds with different numbers of foils per unit volume. The foil concentration of each foil cloud was characterized based on the number of foils it contained, and the statistical values ​​of the scattering field under different foil concentrations were obtained.

[0015] Furthermore, in step 1, when constructing the foil concentration scattering field mapping table, several scattering field statistics for a specified foil concentration are obtained by discrete simulation, and then the scattering field statistics for any foil concentration are obtained by linear interpolation to construct the foil concentration scattering field mapping table; wherein, the foil concentration is characterized based on the number of foils included in a single foil cloud.

[0016] Furthermore, in step 1, the statistical value of the scattered field per unit volume Specifically set as follows:

[0017] With the i-th foil strip in the specified scattering direction Scattered electric field As its scattering electric field in, Specifically set as follows:

[0018]

[0019] Where I0 is the electric field intensity E of the incident radar wave on each foil strip. i The maximum current under the condition, r i The center position of the i-th foil strip. Let be the angle between the direction of the scattered electric field and the foil strip, k be the wave number, and l be the length of the half-wave oscillator. for The unit vector in the direction, where j is the imaginary unit and e is the natural base;

[0020] Based on the scattered electric field of all foil strips within a unit volume The summation yields the statistical value of the scattered field. Right now Where m is the number of foil strips per unit volume. Let be the scattered electric field of the i-th foil strip per unit volume.

[0021] Furthermore, in step 2, the foil cloud model is uniformly divided into multiple voxels using the voxel segmentation method, including:

[0022] Determine the three-dimensional coordinates of each foil strip [x] c ,y c, z c The number of grids on each coordinate axis is calculated based on the minimum and maximum values ​​of the foil cloud on each axis:

[0023] L = floor{[max(x c )-min(x c )] / l x}

[0024] W = floor{[max(y c )-min(y c )] / l y}

[0025] H = floor{[max(z c )-min(z c )] / l z}

[0026] Where floor is the floor function, l x l y l z , respectively, are the side lengths of the voxel on the x, y, and z axes, and L, W, and H are the number of grids divided on the x, y, and z axes, respectively.

[0027] Furthermore, in step 2, the number m of foil strips within each volume element region is counted. j At that time, based on the three-dimensional coordinates [x] of each foil strip c ,y c, z c Determine the grid number of the voxel to which it belongs:

[0028] J = floor{[x c -min(xc )] / l x}

[0029] K = floor{[y c -min(y c )] / l y}

[0030] L = floor{[z c -min(z c )] / l z}

[0031] Where J, K, and L are the grid position indices of the volume element to which the foil belongs on the x, y, and z axes, respectively.

[0032] Furthermore, in step 3, the attenuation coefficient α of each volume element j Specifically set as follows: Where α0 is the initial attenuation coefficient, and k′ is the attenuation constant, which describes the rate attenuation coefficient increases with thickness.

[0033] Furthermore, the initial attenuation coefficient α0 is set to the attenuation level when the outer thickness of the foil cloud is zero or below a specified threshold. Preferably, this specified threshold can be set to 0.1 times the minimum value of the volume element side length, i.e., 0.1*min[l x ,l y ,l z ], where min[l x ,l y ,l z [ ] represents the minimum side length of the volume element.

[0034] The technical solution provided by this invention brings at least the following beneficial effects:

[0035] (1) High accuracy: The present invention uses the voxel segmentation method to divide the foil cloud into multiple voxel regions. This refined segmentation method can more accurately simulate the distribution and quantity of foil in each voxel region, thereby improving the accuracy of echo calculation.

[0036] (2) Consideration of the blocking effect: Considering the blocking effect between each volume element region of the foil cloud under electromagnetic wave irradiation, this invention introduces an attenuation coefficient to simulate this effect. The attenuation coefficient is related to the position of the volume element region in the entire foil cloud, and the closer to the inside of the cloud, the greater the attenuation coefficient. This precise method of determining the attenuation coefficient can more accurately reflect the echo characteristics of different regions, making the calculation results closer to the actual situation.

[0037] (3) High computational efficiency: The foil concentration is defined as the number of foil strips per unit area, which provides a quantitative indicator that allows for comparison and analysis of the electromagnetic properties of different foil clouds. Secondly, the introduction of foil concentration simplifies the electromagnetic scattering problem of complex cloud structures. By dividing the cloud into volumetric regions of different concentrations, the propagation and scattering behavior of electromagnetic waves in the cloud can be simulated and calculated more quickly.

[0038] (4) Strong applicability: This method is applicable to foil clouds of different shapes and sizes, and can adapt to different foil cloud configurations and electromagnetic environments, and has good versatility. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A schematic diagram of the segmentation of the foil cloud.

[0041] Figure 2 A flowchart of a method for calculating electromagnetic scattering of foil clouds based on the volume element method, provided for an embodiment. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be described in detail and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Generally, the components of the embodiments of the present invention described and shown in the accompanying drawings can be arranged and designed using different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the present invention.

[0043] This invention provides a method for calculating the electromagnetic scattering of chaff clouds based on the volume element method. This method divides a three-dimensional chaff cloud into multiple volume element regions, calculates the scattering field value of each region, and then combines the inter-regional blocking effect and attenuation coefficient to obtain the actual scattering field value of the entire chaff cloud. The method proposed in this invention can more accurately simulate the electromagnetic scattering characteristics of chaff clouds under electromagnetic wave irradiation, and has significant application value in fields such as electronic warfare.

[0044] The present invention provides a method for calculating electromagnetic scattering of foil clouds based on the volume element method, comprising the following steps:

[0045] Step 1, construct different foil concentrations ρ per unit volume A With scattered field statistics A one-to-one correspondence of foil concentration scattering field mapping table; in this step, without considering the coupling and shielding effects between foils, different foil concentrations ρ can be mapped per unit volume. A Electromagnetic scattering calculations were performed on the foil clouds, and statistical values ​​of the scattering fields at different concentrations were obtained in advance. A foil concentration scattering field mapping table was then constructed.

[0046] Step 2: Divide the foil cloud model into multiple voxels using the voxel segmentation method. Based on the movement and diffusion state of the foil, determine the number of foil strips m in different voxel regions. j The foil concentration ρ of the volume element is calculated, and the statistical value of the scattered field corresponding to the foil concentration ρ is found in the foil concentration scattering field mapping table. Multiplying by the volume of the volume element yields the scattering field of a single volume element.

[0047] Step 3: In the chaff cloud, the outer regions of the chaff receive electromagnetic waves more easily than the inner regions because the echoes from the outer regions are generally stronger. Therefore, a path depth d is defined for each volumetric region. j The relevant attenuation coefficient α j , where d j This represents the path depth of the electromagnetic wave incident on the foil cloud element in the direction of arrival. The attenuation coefficient is related to the position of the element region within the entire foil cloud; the closer to the interior of the cloud, the greater the attenuation coefficient.

[0048] Step 4: Calculate the actual scattered field value for each volume element region. At this time, it is necessary to use the pre-obtained statistical values ​​of the scattered field. Multiply by the corresponding attenuation coefficient α j (d j This simulates the weakening of electromagnetic field values ​​as they pass through clouds due to blocking and attenuation. It represents the scattered field of each volume element. Its attenuation coefficient α j Multiplying yields the actual scattered field of each volume element region.

[0049] Step 5, the scattering field value of the entire chaff cloud. It is the field value of all volume element regions The summation. Because the echoes from each region have undergone attenuation coefficient adjustments, the final total field value... This can more accurately reflect the actual behavior of clouds under electromagnetic wave illumination. Specifically, it reflects the actual scattering field of all volume elements in the chaff cloud model. The summation value yields the total scattering field value of the foil cloud.

[0050] In one embodiment, when constructing the foil concentration scattering field mapping table, the scattering field statistics are calculated as follows:

[0051] Without considering the coupling and shielding effects between the foils, electromagnetic scattering calculations are performed on foil clouds with different numbers of foils per unit volume to obtain the scattered field values ​​at different foil concentrations. Alternatively, the scattered field values ​​at certain foil concentrations can be obtained through discrete simulation, while the scattered field values ​​at arbitrary foil concentrations are obtained using linear interpolation.

[0052] Generally, the foil concentration ρ is related to the number of foils m, the length of the foil d, the cross-sectional area of ​​the foil s, and the electromagnetic properties σ of the foil material. These factors can be considered comprehensively when obtaining the statistical value of the scattered field.

[0053] Each foil strip is subjected to the radar incident wave electric field intensity E i Under the influence of [something], an induced current will be generated inside the foil. The intensity of the induced current is not uniformly distributed inside the foil, with the maximum value located at the geometric center of the foil. The expression for the maximum current value is:

[0054]

[0055] Where λ is the radar operating wavelength, R ∑ Let θ be the radiation resistance of the foil strip, and θ be the angle between the foil strip axis and the direction of the radar incident wave.

[0056] Then the foil strip is The scattered electric field in the direction is:

[0057]

[0058] Where, r i Indicates the center position of the i-th foil strip. λ is the angle between the direction of the scattered electric field and the foil strip, k represents the wave number (in this embodiment, k = 2π / λ), l is the length of the half-wave oscillator, j is the imaginary unit, and e is the natural base. for.

[0059] By superimposing the echoes from each foil strip, the statistical value of the scattered field with a foil strip concentration of ρ per unit volume can be obtained:

[0060]

[0061] In one embodiment, the segmentation of the foil cloud in step 2 specifically involves:

[0062] The foil cloud model was segmented into multiple voxels using the voxel segmentation method, such as... Figure 1As shown, first, the coordinates [x] of each foil strip are determined. c ,y c, z c [The task is to] find the minimum and maximum values ​​of the chaff cloud on each coordinate axis in order to construct a cube containing all the chaff. This is based on the required volumetric element side length l. x l y l z The bounding box of the foil cloud [min(x c ),min(y c ),min(z c )]、[max(x c ),max(y c ),max(z c [)] can calculate the number of grids that need to be divided on each coordinate axis (the coordinate axes in the x, y, and z directions).

[0063]

[0064] Here, floor is a function that rounds down. That is, L, W, and H represent the number of grid cells divided along the x, y, and z axes, respectively.

[0065] Once the voxel segmentation of the foil cloud model is completed, the relative position of the foil coordinates and the voxel boundary can be calculated based on the foil coordinates to determine the mesh number of the voxel region to which each foil belongs, as shown in formula (5):

[0066]

[0067] Where J, K, and L are the grid position indices of the voxel to which the foil belongs on the x, y, and z axes, respectively, and the grid number of the voxel to which the current foil belongs is determined according to (J, K, L).

[0068] Finally, the number of foil strips (m) within each volumetric region is counted. Based on the actual distribution of the foil cloud, the number of foil strips varies within each volumetric region, and the distribution decreases from the inside out. The foil strip concentration (ρ) within the volumetric region is then calculated. For example, this can be done using the formula... The foil concentration is calculated, where V is the volume of the volume element.

[0069] Find the scattering field statistics corresponding to the foil concentration ρ in the foil concentration scattering field mapping table. The scattering field values ​​of volume elements with different numbers of foil strips It is related to the foil concentration ρ and the volume A of the volume element, as shown in the following formula:

[0070]

[0071] In one embodiment, the attenuation coefficient in step 3 is specifically calculated as follows:

[0072] Under electromagnetic wave irradiation, the foil strips within each volume element region will generate a certain amount of echo. Based on the number and distribution of the foil strips, the attenuation coefficient within each volume element region is calculated. The attenuation coefficient is related to the volume element's position within the entire foil cloud; the closer to the interior of the cloud, the greater the attenuation coefficient. The attenuation coefficient can be obtained through experimental data or theoretical calculations. For the j-th volume element, its attenuation coefficient α... j The calculation formula can be expressed as:

[0073]

[0074] Where α0 is the initial attenuation coefficient, representing the attenuation level when the thickness outside the cloud is zero or very thin (below a specified value), k is the attenuation constant, used to describe the rate attenuation coefficient increases with thickness, and d... j This represents the path depth of the electromagnetic wave incident on the cloud element of the foil strip in the direction of the incoming electromagnetic wave, as d... j The increase of the attenuation coefficient α j It shows an increasing trend.

[0075] In one embodiment, in step 4, the actual scattered field value of each voxel region is obtained based on the scattered field value attenuated between voxels:

[0076] In calculating the actual echo value, the electromagnetic scattering statistics of the volume element are first calculated based on the foil concentration ρ and the volume A of the volume element region. This is the scattered field value calculated based on the number of chaff strips and the electric field strength of the radar incident wave, without considering any attenuation or obstruction. Then, this scattered field value is multiplied by the corresponding attenuation coefficient α. j The actual scattered field value of each volume element region is obtained. for:

[0077]

[0078] In one embodiment, step 5 specifically includes:

[0079] The scattered field values ​​of each volume element are summed to obtain the scattered field value of the entire chaff cloud. The formula for calculating the total scattered field value is as follows:

[0080]

[0081] in, This is the total scattered radar signal value from the entire chaff cloud. In this formula, n is the total number of voxels, representing the number of voxels in the entire chaff cloud, and the scattered field value of each voxel. The calculation is performed by considering factors such as the number of chaff strips within the volume element, the electric field strength of the incident radar wave, the reflection coefficient, and the attenuation coefficient. This summation process ensures that the structure of the chaff cloud and the propagation characteristics of the electromagnetic wave are fully considered. It takes into account the shielding effect within the chaff cloud and the energy attenuation of the electromagnetic wave.

[0082] As one possible implementation, such as Figure 2 As shown, the electromagnetic scattering calculation method for foil clouds based on the volume element method provided in this embodiment of the invention includes the following processing steps:

[0083] Step S1: Construct a foil concentration scattering field mapping table, establish a foil cloud model, and determine the foil coordinates;

[0084] Step S2: Determine the boundary and volume element side length of the foil cloud, and calculate and determine the volume element to which the foil belongs;

[0085] Step S3: Detect whether the foil strip belongs to the current volume element. If yes, continue to step S4; otherwise, return to step S2.

[0086] Step S4: Count the number of foil strips and calculate the foil concentration of the volume element;

[0087] Step S5: Find the scattering field value E1 corresponding to the current foil concentration in the foil concentration scattering field mapping table, thus obtaining...

[0088] Step S6: Based on the volume of the volume element, calculate the scattering field value E2 of the volume element, that is, calculate it according to formula (6).

[0089] Step S7: Calculate the attenuation coefficient of the voxel region (related to the voxel position);

[0090] Step S8: Calculate the scattering field value E3 of the volume element after attenuation, which is obtained according to formula (8).

[0091] Step S9: Check if all voxels have been calculated. If yes, proceed to step S10; otherwise, return to step S4.

[0092] Step S10: Sum the echo values ​​of the entire foil cloud.

[0093] The electromagnetic scattering calculation method for chaff clouds based on the volume element method provided in this invention can more accurately simulate the electromagnetic scattering characteristics of chaff clouds under electromagnetic wave illumination. In particular, after considering the internal structure and shielding effect of the chaff cloud, it can provide more accurate echo prediction, which is of great significance for improving the accuracy of radar signal processing and the defensive effect of chaff clouds.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0095] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for calculating electromagnetic scattering from foil clouds based on the volume element method, characterized in that, Includes the following steps: Step 1: Construct different foil concentrations per unit volume With scattered field statistics A one-to-one correspondence of foil concentration scattering field mapping table; Step 2: Divide the foil cloud model into multiple voxels using the voxel segmentation method, and count the number of foil strips in each voxel region. ,based on The cumulative value of the foil concentration is used to obtain the foil concentration of the volume element. ; Find the corresponding foil concentration for each volume element in the foil concentration scattering field mapping table. Statistical value of scattered field and will Multiplying by the volume of the volume element yields the scattering field of a single volume element. ; Step 3: Set the attenuation coefficient for each volume element. The attenuation coefficient The path depth of the electromagnetic wave incident on the current volume element in the direction of the incoming wave. Positive correlation; Step 4: scatter the field of each volume element. With attenuation coefficient Multiplying yields the actual scattered field of each volume element. ; Step 5: Actual scattering field of all volume elements based on the chaff cloud model The summation yields the total scattering field value of the foil cloud. ; In step 1, when constructing the foil concentration scattering field mapping table, several scattering field statistics for a specified foil concentration are obtained by discrete simulation, and then the scattering field statistics for any foil concentration are obtained by linear interpolation to construct the foil concentration scattering field mapping table; wherein, the foil concentration is characterized based on the number of foils included in a single foil cloud. Statistical value of scattered field per unit volume Specifically set as follows: With the first Root foil strip in the specified scattering direction Scattered electric field As its scattering electric field ,in, Specifically set as follows: in, The electric field strength of each foil strip under radar incident wave The maximum current under the condition, For the first The center position of the root foil strip, The angle between the direction of the scattered electric field and the foil strip is... For wave number, The length of the half-wave dipole. for The unit vector of direction. The imaginary unit, The base is the natural number; Based on the scattered electric field of all foil strips within a unit volume The summation yields the statistical value of the scattered field. .

2. The method as described in claim 1, characterized in that, In step 1, when constructing the foil concentration scattering field mapping table, the scattering field statistics are calculated as follows: Without considering the coupling and shielding effects between the foils, electromagnetic scattering calculations were performed on foil clouds with different numbers of foils per unit volume. The foil concentration of each foil cloud was characterized based on the number of foils it contained, and the statistical values ​​of the scattering field under different foil concentrations were obtained.

3. The method as described in claim 1, characterized in that, In step 2, the foil cloud model is uniformly divided into multiple voxels using the voxel segmentation method, including: Determine the three-dimensional coordinates of each foil strip. The number of grids on each coordinate axis is calculated based on the minimum and maximum values ​​of the foil cloud on each axis: in, It is a function that rounds down. , , , respectively, are the side lengths of the voxel on the x, y, and z axes, and L, W, and H are the number of grids divided on the x, y, and z axes, respectively.

4. The method as described in claim 3, characterized in that, In step 2, the number of foil strips in each volumetric region is counted. At that time, based on the three-dimensional coordinates of each foil strip [ Determine the grid number of the voxel to which it belongs: Where J, K, and L are the grid position indices of the volume element to which the foil belongs on the x, y, and z axes, respectively.

5. The method as described in claim 1, characterized in that, In step 3, the attenuation coefficient of each volume element Specifically set as follows: ,in, The initial attenuation coefficient is set. is the attenuation constant, used to describe the rate attenuation coefficient increases with thickness.

6. The method as described in claim 5, characterized in that, Initial attenuation coefficient Sets the attenuation level when the outer thickness of the foil cloud is zero or below a specified threshold.

7. The method as described in claim 6, characterized in that, Set the initial attenuation coefficient When the threshold is specified, it is set to 0.1 times the minimum side length of the volume element.

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