Bar cloud cluster electromagnetic scattering calculation method based on volume element method

Abstract

The invention discloses a chaff cloud cluster electromagnetic scattering calculation method based on a volume element method, and belongs to the technical field of chaff electromagnetic scattering. According to the method, the three-dimensional chaff cloud cluster is divided into a plurality of voxel regions, the scattering field value of each region is calculated, and then the actual scattering field value of the whole chaff cloud cluster is obtained by combining the shielding effect and the attenuation coefficient between the regions. The method provided by the invention can more accurately simulate the electromagnetic scattering characteristics of the chaff cloud cluster under the irradiation of electromagnetic waves, and has important application value in the fields of electronic countermeasures and the like.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic scattering of foil strips, and in particular to a calculation method for electromagnetic scattering of a foil strip cloud based on a volume element method. Background Art

[0002] As the most widely used passive jammer, chaff plays an extremely important role in electronic countermeasures due to its simple manufacture, easy use and significant effect. In order to give full play to the jamming effect of chaff in electronic countermeasures, it is urgent to master its motion diffusion, electromagnetic scattering, radio wave propagation and other related characteristics in the atmosphere. Therefore, the motion diffusion model of chaff cloud and the related research on electromagnetic scattering characteristics have gradually become the research object of researchers engaged in target characteristics at home and abroad.

[0003] At present, the calculation method of electromagnetic scattering of chaff cloud often adopts a simplified model, which ignores the coupling and shielding effect between chaff strips, as well as the shielding effect between different areas inside the cloud. This leads to a large deviation between the calculation results and the actual electromagnetic scattering characteristics. Therefore, it is necessary to propose a more efficient and accurate calculation method for electromagnetic scattering of chaff cloud, so as to more accurately simulate the electromagnetic scattering characteristics of chaff cloud. Summary of the invention

[0004] The present invention proposes a method for calculating the electromagnetic scattering of a foil cloud based on the voxel method. The method adopts the voxel method to accurately calculate the scattering field of the entire foil cloud by dividing the foil cloud into multiple voxel regions and considering the foil concentration and attenuation coefficient of each region, so as to realize efficient and accurate calculation of the electromagnetic scattering of the foil cloud.

[0005] The technical solution adopted by the present invention is:

[0006] A method for calculating electromagnetic scattering of a chaff cloud based on a volume element method comprises the following steps:

[0007] Step 1: Construct different foil concentrations ρ per unit volume A and scattered field statistics One-to-one correspondence between foil concentration scattering field mapping table;

[0008] Step 2: Use the volume segmentation method to evenly divide the foil cloud model into multiple volume elements (i.e., each volume element is a foil cloud volume element), and count the number of foil strips m in each volume element area. j , based on m j The cumulative value of the root chaff concentration is the chaff concentration ρ of the volume element;

[0009] Find the scattering field statistics corresponding to the foil concentration ρ of each voxel in the foil concentration scattering field mapping table and will Multiply by the volume of the voxel to get the scattered field of a single voxel

[0010] Step 3: Set the attenuation coefficient α of each voxel j , the attenuation coefficient α j The path depth d of the electromagnetic wave incident to the current voxel in the direction of the incoming wave j Positive correlation;

[0011] Step 4: The scattered field of each voxel With the attenuation coefficient α j Multiply to get the actual scattered field of each voxel

[0012] Step 5: Actual scattering fields of all voxels based on the chaff cloud model The total scattering field value of the foil cloud is obtained by adding the cumulative sum of

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

[0014] Without considering the coupling and shielding effect between foil strips, electromagnetic scattering calculations are carried out on foil clouds with different numbers of foil strips in a unit volume. The foil concentration of each foil cloud is characterized based on the number of foil strips it includes, and the statistical values ​​of the scattering field at different foil concentrations are calculated.

[0015] Furthermore, in step 1, when constructing the foil strip concentration scattering field mapping table, the scattering field statistical values ​​of several specified foil strip concentrations are obtained through discrete simulation, and then the scattering field statistical values ​​under any foil strip concentration are obtained through linear interpolation to construct the foil strip concentration scattering field mapping table; wherein the foil strip concentration is characterized based on the number of foil strips included in a single foil strip cloud.

[0016] Furthermore, in step 1, the scattering field statistics per unit volume The specific settings are:

[0017] The scattering direction of the i-th foil strip is specified. The scattered electric field As its scattered electric field in, The specific settings are:

[0018]

[0019] Among them, I0 is the electric field strength E of each foil strip at the radar incident wave i The maximum current under r i is the center position of the i-th foil strip, is the angle between the scattered electric field direction and the foil strip, k is the wave number, l is the half-wave oscillator length, for The unit vector of the direction, j is the imaginary unit, and e is the natural base;

[0020] Based on the scattered electric field of all foil strips in a unit volume The scattering field statistics are obtained by adding the sum of Right now Where m is the number of foil strips per unit volume, is the scattered electric field of the i-th foil strip within the unit volume.

[0021] Furthermore, in step 2, the foil cloud model is evenly divided into a plurality of voxels using a 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 chaff cloud on each coordinate 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] Among them, floor is the function of rounding down, l x , l y , l z are the side lengths of the voxel unit on the x, y, and z axes respectively, 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 of foil strips m in each voxel area is counted. j When the three-dimensional coordinates [x 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] Among them, J, K, and L are the grid position indexes of the element to which the foil strip belongs on the x, y, and z axes respectively.

[0032] Furthermore, in step 3, the attenuation coefficient α of each voxel is j The specific settings are: Among them, α0 is the set initial attenuation coefficient, and k′ is the attenuation constant, which is used to describe the rate at which the 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 the thickness is lower than a specified threshold. Preferably, the specified threshold can be set to: 0.1 times the minimum value of the side length of the voxel. That is, 0.1*min[l x ,l y ,l z ], where min[l x ,l y ,l z ] is the minimum value of the side length of the voxel.

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

[0035] (1) High accuracy: The present invention uses a voxel segmentation method to segment 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 shielding effect: Considering the shielding effect between each voxel area of ​​the foil cloud under electromagnetic wave irradiation, the present invention introduces an attenuation coefficient to simulate this effect. The attenuation coefficient is related to the position of the voxel area in the entire foil cloud. The closer to the inside of the cloud, the greater the attenuation coefficient. This precise attenuation coefficient determination method can more accurately reflect the echo characteristics of different areas, making the calculation results closer to the actual situation.

[0037] (3) High computational efficiency: The definition of foil density, that is, the number of foil strips per unit area, provides a quantitative index that allows the electromagnetic characteristics of different foil clouds to be compared and analyzed. Secondly, the introduction of foil density simplifies the electromagnetic scattering problem of complex cloud structures. By dividing the cloud into volume elements with 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

[0041] Figure 2 A flow chart of a method for calculating electromagnetic scattering of a cloud of foil strips based on the voxel method provided in an embodiment. DETAILED DESCRIPTION

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

[0043] The embodiment of the present invention provides a method for calculating electromagnetic scattering of a chaff cloud based on the voxel method. The method divides a three-dimensional chaff cloud into multiple voxel regions, calculates the scattering field value of each region, and then combines the shielding effect and attenuation coefficient between regions to obtain the actual scattering field value of the entire chaff cloud. The method proposed in the embodiment of the present invention can more accurately simulate the electromagnetic scattering characteristics of a chaff cloud under electromagnetic wave irradiation, and has important application value in fields such as electronic countermeasures.

[0044] A method for calculating electromagnetic scattering of a foil cloud based on a voxel method provided in an embodiment of the present invention comprises the following steps:

[0045] Step 1: Construct different foil concentrations ρ per unit volume A and scattered field statistics One-to-one corresponding foil concentration scattering field mapping table; In this step, without considering the coupling and shielding effect between foil strips, different foil concentrations ρ can be mapped in unit volume. A Electromagnetic scattering calculations are performed on the foil cloud to obtain statistical values ​​of scattering fields of different concentrations in advance. Then a foil strip concentration scattering field mapping table is constructed.

[0046] Step 2: The foil cloud model is segmented into multiple voxels using the voxel segmentation method. According to the movement and diffusion state of the foil, the number of foil strips in different voxel areas is obtained. j , the foil concentration ρ of the volume element is obtained by calculation, and the scattering field statistics corresponding to the foil concentration ρ is found in the foil concentration scattering field mapping table And multiply it by the volume of the voxel to get the scattered field of a single voxel

[0047] Step 3: In the foil cloud, the foil in the outer area is more likely to receive electromagnetic waves than the foil in the inner area, because the echo in the outer area is usually stronger than the echo in the inner area. Therefore, a path depth d is defined for each voxel area. j The associated attenuation coefficient α j , where d j is the path depth of the electromagnetic wave incident on the foil cloud element in the direction of the incoming wave. The attenuation coefficient is related to the position of the element area in the entire foil cloud. The closer to the inside of the cloud, the greater the attenuation coefficient.

[0048] Step 4: Calculate the actual scattered field value of each voxel area When the scattering field statistics are obtained in advance, Multiply by the corresponding attenuation coefficient α j (d j ). This can simulate the weakening of the field value caused by shielding and attenuation of electromagnetic waves when passing through clouds. Its attenuation coefficient α j Multiply to get the actual scattered field of each voxel area

[0049] Step 5: Scattering field value of the entire foil cloud is the field value of all voxels Since the echoes in each area have been adjusted by the attenuation coefficient, the final total field value It can more accurately reflect the actual performance of clouds under electromagnetic wave irradiation. That is, the actual scattering field of all voxels based on the foil cloud model The cumulative value of the scattering field of the foil cloud is

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

[0051] Without considering the coupling and shielding effect between foil strips, the electromagnetic scattering calculation is performed on the foil cloud with different numbers of foil strips in a unit volume to obtain the scattering field values ​​at different foil strip concentrations. The scattering field values ​​of certain foil strip concentrations can also be obtained by discrete simulation, and the scattering field values ​​at any foil strip concentration can be obtained by linear interpolation.

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

[0053] Each foil strip has an electric field strength E of the radar incident wave. i Under the action of , an induced current will be generated inside the foil strip. The intensity of the induced current is unevenly distributed inside the foil strip, and the maximum value is at the geometric center of the foil strip. The expression of the maximum current is:

[0054]

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

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

[0057]

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

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

[0060]

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

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

[0063]

[0064] Among them, floor is a function that rounds down to an integer. That is, L, W, and H are the number of grids divided on the x, y, and z axes respectively.

[0065] After the voxel segmentation of the foil cloud model is completed, the relative position of the foil coordinates and the voxel boundary can be calculated according to the foil coordinates, and the voxel area grid number to which each foil belongs can be determined, as shown in formula (5):

[0066]

[0067] Among them, J, K, and L are the grid position indexes of the volume element to which the foil strip belongs on the x, y, and z axes respectively, and then the grid number of the volume element to which the current foil strip belongs is determined according to (J, K, L).

[0068] Finally, the number of foil strips m contained in each volume element is counted. According to the actual distribution of the foil strip cloud, the number of foil strips in each volume element is different, and the number distribution decreases from the inside to the outside. The foil strip concentration ρ in the volume element is calculated. For example, the formula can be used Perform foil concentration calculations, where V is the volume of the voxel.

[0069] Find the scattering field statistics corresponding to the foil concentration ρ in the foil concentration scattering field mapping table The scattered field value of the volume element containing different numbers of foil strips is It is related to the foil concentration ρ and the volume A of the voxel, as shown in the following formula:

[0070]

[0071] In one embodiment, the specific calculation of the attenuation coefficient in step 3 is:

[0072] Under electromagnetic wave irradiation, the foil strips in each volume element area will generate a certain echo. According to the number and distribution of foil strips, the attenuation coefficient in each volume element area is calculated. The attenuation coefficient is related to the position of the volume element in the entire foil strip cloud. The closer to the inside of the cloud, the greater the attenuation coefficient. The attenuation coefficient can be obtained through experimental data or theoretical calculation. For the jth volume element unit, its attenuation coefficient α j The calculation formula can be expressed as:

[0073]

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

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

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

[0077]

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

[0079] The scattering field value of each voxel is summed to obtain the scattering field value of the entire foil cloud. The total scattering field value calculation formula is as follows:

[0080]

[0081] in, is the total scattering field value of the entire chaff cloud to the radar signal. In this formula, n is the total number of voxels, indicating the number of voxels divided in the entire chaff cloud. The scattering field value of each voxel is It is calculated by considering the number of foil strips in the voxel, the electric field strength of the radar incident wave, the reflection coefficient, and the attenuation coefficient. This summation process ensures that the structure of the foil cloud and the propagation characteristics of the electromagnetic wave can be fully considered. It takes into account the shielding effect inside the foil cloud and the energy attenuation of the electromagnetic wave.

[0082] As a possible implementation, Figure 2 As shown, the method for calculating electromagnetic scattering of foil cloud based on the voxel method provided in the embodiment of the present invention includes the following processing steps:

[0083] Step S1, constructing a foil strip concentration scattering field mapping table, establishing a foil strip cloud model, and determining the foil strip coordinates;

[0084] Step S2, determining the boundary and the side length of the foil strip cloud, and calculating and determining the voxel unit to which the foil strip belongs;

[0085] Step S3, detecting whether the foil strip belongs to the current voxel, if so, proceeding to step S4; otherwise, returning to step S2;

[0086] Step S4, counting the number of foil strips and calculating the foil strip concentration of the volume element;

[0087] Step S5, searching the scattering field value E1 corresponding to the current foil concentration in the foil concentration scattering field mapping table, that is, obtaining

[0088] Step S6, combining the volume of the voxel, calculate the scattering field value E2 of the voxel, that is, calculate according to formula (6)

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

[0090] Step S8, calculate the scattering field value E3 of the attenuated volume element, that is, according to formula (8),

[0091] Step S9, checking whether all voxels have been calculated, if so, executing step S10; otherwise, returning to executing step S4;

[0092] Step S10, summing up to obtain the echo value of the entire foil cloud.

[0093] The voxel-based calculation method for electromagnetic scattering of a chaff cloud provided in an embodiment of the present invention can more accurately simulate the electromagnetic scattering characteristics of a chaff cloud under electromagnetic wave irradiation, especially after considering the internal structure and shielding effect of the chaff cloud, and can provide more accurate echo prediction, which is of great significance for improving the accuracy of radar signal processing and the defensive effect of the chaff cloud.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0095] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for calculating electromagnetic scattering of foil cloud based on volume element method, characterized in that: The following steps are involved: Step 1: Construct different foil concentrations ρ per unit volume A and scattered field statistics One-to-one correspondence between foil concentration scattering field mapping table; Step 2: Use the volume segmentation method to evenly divide the foil cloud model into multiple volume elements, and count the number of foil strips m in each volume element area. j , based on m j The cumulative value of the root chaff concentration is the chaff concentration ρ of the volume element; Find the scattering field statistics corresponding to the foil concentration ρ of each voxel in the foil concentration scattering field mapping table and will Multiply by the volume of the voxel to get the scattered field of a single voxel Step 3: Set the attenuation coefficient α of each voxel j , the attenuation coefficient α j The path depth d of the electromagnetic wave incident to the current voxel in the direction of the incoming wave j Positive correlation; Step 4: The scattered field of each voxel With the attenuation coefficient α j Multiply to get the actual scattered field of each voxel Step 5: Actual scattering fields of all voxels based on the chaff cloud model The total scattering field value of the foil cloud is obtained by adding the cumulative sum of 2. The method according to claim 1, characterized in that In step 1, when constructing the foil strip concentration scattering field mapping table, the scattering field statistics are calculated as: Without considering the coupling and shielding effect between foil strips, electromagnetic scattering calculations are carried out on foil clouds with different numbers of foil strips in a unit volume. The foil concentration of each foil cloud is characterized based on the number of foil strips it includes, and the statistical values ​​of the scattering field at different foil concentrations are calculated.

3. The method according to claim 1, characterized in that In step 1, when constructing the foil strip concentration scattering field mapping table, the scattering field statistical values ​​of several specified foil strip concentrations are obtained through discrete simulation, and then the scattering field statistical values ​​under any foil strip concentration are obtained through linear interpolation to construct the foil strip concentration scattering field mapping table; wherein the foil strip concentration is characterized based on the number of foil strips included in a single foil strip cloud.

4. The method according to any one of claims 1 to 3, characterized in that In step 1, the scattered field statistics per unit volume are The specific settings are: The scattering direction of the i-th foil strip is specified. The scattered electric field As its scattered electric field in, The specific settings are: Among them, I0 is the electric field strength E of each foil strip in the radar incident wave i The maximum current under r i is the center position of the i-th foil strip, is the angle between the scattered electric field direction and the foil strip, k is the wave number, l is the half-wave oscillator length, for The unit vector of the direction, j is the imaginary unit, and e is the natural base; Based on the scattered electric field of all foil strips in a unit volume The scattering field statistics are obtained by adding the sum of 5. The method according to claim 1, characterized in that In step 2, the foil cloud model is evenly divided into multiple voxels using the voxel segmentation method, including: 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 chaff cloud on each coordinate axis: L=floor{[max(x c )-min(x c )] / l x } W=floor{[max(y c )-min(y c )] / l y } H=floor{[max(z c )-min(z c )] / l z } Among them, floor is the function of rounding down, l x , l y , l z are the side lengths of the voxel unit on the x, y, and z axes respectively, and L, W, and H are the number of grids divided on the x, y, and z axes respectively.

6. The method according to claim 5, characterized in that In step 2, the number of foil strips m in each voxel area is counted. j When the three-dimensional coordinates [x c ,y c, z c ] Determine the grid number of the voxel to which it belongs: J=floor{[x c -min(x c )] / l x } K=floor{[and c -min(and c )] / l y } L=floor{[z c -min(z c )] / l z } Among them, J, K, and L are the grid position indexes of the element to which the foil strip belongs on the x, y, and z axes respectively.

7. The method according to claim 1, characterized in that In step 3, the attenuation coefficient α of each voxel is j The specific settings are: Among them, α0 is the set initial attenuation coefficient, and k′ is the attenuation constant, which is used to describe the rate at which the attenuation coefficient increases with thickness.

8. The method according to claim 7, characterized in that The initial attenuation coefficient α0 is set to the attenuation level when the outer thickness of the chaff cloud is zero or the thickness is below a specified threshold.

9. The method according to claim 8, characterized in that When setting the initial attenuation coefficient α0, the specified threshold is set to: 0.1 times the minimum value of the voxel side length.

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