A method for jointly simulating a foil curtain and a millimeter wave radiation image of a detected target
By establishing a three-dimensional physical model of the chaff curtain and the detection target and performing surface subdivision, the average current and dielectric constant are calculated, and the millimeter-wave radiation image of the chaff curtain and the detection target is jointly simulated. This solves the problems of low computational efficiency and insufficient influence analysis of the chaff curtain, and provides a basis for detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUAZHONG UNIV OF SCI & TECH
- Filing Date
- 2023-04-12
- Publication Date
- 2026-06-26
AI Technical Summary
Existing technologies neglect the coupling and blocking effects between chaff strips when calculating the electromagnetic scattering characteristics of chaff curtains, resulting in low computational efficiency and a lack of analysis on the impact of chaff curtains on the millimeter-wave radiation of the target.
A three-dimensional physical model of the chaff curtain and the detection target is established. Node numbers and coordinates are obtained through surface element partitioning. The average current and effective dielectric constant are calculated by dividing the model into sub-blocks, which are equivalent to a two-dimensional plane. Combined with ray tracing and brightness temperature calculation, the millimeter-wave radiation images of the chaff curtain and the detection target are jointly simulated.
It improves computational efficiency, can adaptively adjust the size and shape of the chaff curtain model, analyze the impact of the chaff curtain on the millimeter-wave radiation of the target, and provide a basis for the detection of the target.
Smart Images
Figure CN116522762B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electromagnetic simulation technology, and more specifically, relates to a method for joint simulation of millimeter-wave radiation images of a foil screen and a detection target. Background Technology
[0002] Chalcohol, a widely used passive jamming agent, is typically a half-wavelength metal wire or metal-coated material with a diameter between 1 / 100 and 1 / 200 of the radar wavelength. Besides chaff, there are also special types such as sheet chaff, inflatable chaff, and jamming ropes. When a large number of chaff strips are dispersed in the air to form a chaff curtain with a certain length, height, and thickness, the chaff curtain scatters or attenuates the electromagnetic waves emitted or scattered by the radar and the target, making the target difficult to detect. Chaff jamming remains one of the main threats faced by advanced anti-ship radar seekers.
[0003] Current research on chaff curtains, both domestically and internationally, largely focuses on calculating their scattering characteristics. Traditional methods for calculating chaff curtain scattering characteristics typically ignore coupling and obstruction between chaff strips, treating a single chaff strip as an equivalent dipole antenna or conductor. The coupling and obstruction effects between chaff strips intensify with increasing chaff curtain density. When the chaff curtain is very dense, its impact on the calculation of the electromagnetic scattering cross-section becomes non-negligible. In this case, the calculation of the electromagnetic scattering characteristics of chaff curtains mainly includes numerical methods such as the method of moments and vector transmission theory methods based on statistical principles. Equivalent methods for single chaff strips, as well as general iterative and analytical methods, require calculating the radar cross-section of each chaff strip, resulting in low computational efficiency and significant limitations on the number of chaff strips. To improve computational efficiency, the chaff curtain is divided into certain chaff unit cells according to chaff density. The radar cross-section of each chaff unit cell is calculated separately, and then, considering the obstruction effect between unit cells, the radar cross-sections of each unit cell are superimposed to obtain the radar cross-section of the entire chaff curtain. However, the millimeter-wave radiation characteristics of chaff curtains and their impact on the millimeter-wave radiation of detected targets have not yet been analyzed. Summary of the Invention
[0004] To address the shortcomings and improvement needs of existing technologies, this invention provides a joint simulation method for millimeter-wave radiation images of chaff and detection targets. It considers the mutual influence between the chaff and the detection target, analyzes the impact of the chaff on the millimeter-wave radiation detection of the target, and provides a basis for the detection of the target.
[0005] To achieve the above objectives, on the one hand, the present invention provides a method for joint simulation of millimeter-wave radiation images of a chaff screen and a detection target, comprising:
[0006] Three-dimensional physical models of the chaff screen and the detection target were established separately;
[0007] The three-dimensional physical model of the target is divided into surface elements, and the node number and node coordinates of each surface element of the target are obtained.
[0008] The three-dimensional physical model of the foil curtain is divided into multiple sub-blocks, and the average current and effective dielectric constant of each sub-block are calculated based on the zenith angle, azimuth angle and length of each foil strip in the sub-block.
[0009] Based on the effective dielectric constants, the three-dimensional physical model of the foil curtain is equivalent to a two-dimensional plane, and the emissivity, reflectivity, and transmittance of each sub-plane on the two-dimensional plane are obtained; then, the two-dimensional plane is divided into surface elements to obtain the node number and node coordinates of each foil curtain surface element.
[0010] For each foil curtain element, the ray tracking path and the elements intersecting the tracking path are determined based on the incident coordinates and direction of the ray incident on the foil curtain element and the node coordinates of all elements. The brightness temperature of each element intersecting the ray is determined sequentially by reverse tracking, thereby obtaining the brightness temperature of each foil curtain element and outputting a joint simulation image of millimeter-wave radiation of the foil curtain and the detection target.
[0011] Further, the calculation of the average current of each sub-block based on the zenith angle, azimuth angle, and length of each foil strip in the sub-block includes:
[0012] Based on the zenith angle, azimuth angle, and length of each foil strip in the sub-block, the current component of each foil strip is calculated using the method of moments; then, the average current of each sub-block is calculated using the current component and the direction distribution function.
[0013] Furthermore, the effective dielectric constant of each sub-block is expressed as:
[0014]
[0015] Where p and q are the zenith angle θ or azimuth angle φ, ε0 is the dielectric constant of air, j is the imaginary part, and η0, ρ, L, and λ represent the intrinsic impedance of free space, the average density of the foil, the length of the foil, and the wavelength in free space, respectively. pq The average current of the sub-block.
[0016] Further, the step of equating the three-dimensional physical model of the foil curtain to a two-dimensional plane based on the effective dielectric constants of each plane, and obtaining the emissivity, reflectivity, and transmittance of each sub-plane on the two-dimensional plane, includes:
[0017] Based on the effective dielectric constant and the theory of reflection and transmission in a multilayer medium field, the three-dimensional physical model of the foil curtain is equivalent to a two-dimensional plane, and the reflection coefficient R and transmission coefficient T of each sub-plane on the two-dimensional plane are calculated; the emissivity e, reflectivity Γ, and transmittance Υ of each sub-plane on the two-dimensional plane are expressed as: e = 1 - Γ - Υ, Γ = |R|2 , Υ=|T| 2 .
[0018] Furthermore, the foil strip screen element is a triangular element;
[0019] If column j of the foil strip element in the two-dimensional plane is even, then the node numbers of the three vertices of the triangular element are as follows:
[0020] v1=i+n×([j / 2]-1)+1
[0021] v2=i+n×([j / 2]+1)+1
[0022] v3 = i + n × ([j / 2] + 1)
[0023] If column j of the foil strip element in the two-dimensional plane is odd, then the node numbers of the three vertices of the triangular element are as follows:
[0024] v1 = i + n × [j / 2]
[0025] v2 = i + n × [j / 2] + 1
[0026] v3 = i + n × ([j / 2] + 1)
[0027] Where i = 1, 2, ..., n, j = 1, 2, ..., 2*m-2, m is the number of divisions along the y-axis, n is the number of divisions along the z-axis, and the coordinates of each node number are determined by its actual position and sorted according to the corresponding node number.
[0028] Furthermore, before determining the ray tracking path and the surface elements intersecting the tracking path for each foil screen element based on the incident coordinates and direction of the ray incident on that foil screen element and the node coordinates of all surface elements, the method further includes:
[0029] Merge the node numbers and node coordinates of all foil screen elements and detection target elements;
[0030] After merging, the node numbers of the target detection elements remain unchanged, while the node numbers of the foil curtain elements are:
[0031] Node1(v1,v2,v3)=Node1(v1,v2,v3)+P
[0032] Where P is the number of surface element nodes of the target being detected.
[0033] Furthermore, the step of determining the brightness temperature of each surface element intersecting the ray sequentially by reverse tracing includes:
[0034] When rays are incident on a foil screen element, the brightness temperature of that foil screen element is expressed as:
[0035] TB (l) =e1×T0+Γ1×T env +Υ1×TB (l-1)
[0036] In the formula, e1, Γ1, and Υ1 are the emissivity, reflectivity, and transmittance of the foil screen element, respectively; l is the current tracking count; T0 is the ambient physical temperature; and T... env For ambient brightness temperature, TB (l-1) The brightness temperature is the value after the previous tracking.
[0037] When rays are reflected onto the foil screen element, the brightness temperature of that foil screen element is expressed as:
[0038] TB (l) =e2×T0+Γ2×TB (l-1) +Υ2×T env
[0039] In the formula, e2, Γ2, and Υ2 are the emissivity, reflectivity, and transmittance of the foil screen element, respectively; l is the current tracking count; T0 is the ambient physical temperature; and T env For ambient brightness temperature, TB (l-1) The brightness temperature is the value after the previous tracking.
[0040] When rays are incident on or reflected onto the target surface element, the brightness temperature of that target surface element is expressed as:
[0041] TB (l) =e3×T0+Γ3×TB (l-1)
[0042] In the formula, e3 and Γ3 are the emissivity and reflectivity of the detected target surface element, respectively, l is the current tracking count, T0 is the ambient physical temperature, and TB is the ambient temperature. (l-1) This is the brightness temperature after the previous tracking.
[0043] On the other hand, the present invention provides a joint simulation system for millimeter-wave radiation images of a foil screen and a detection target, comprising: a computer-readable storage medium and a processor;
[0044] The computer-readable storage medium is used to store executable instructions;
[0045] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the above-described co-simulation method of the foil screen and the millimeter-wave radiation image of the detection target.
[0046] In summary, compared with the prior art, the above technical solutions proposed by this invention can achieve the following beneficial effects:
[0047] This invention addresses the problem of traditional geometric modeling's inability to adaptively change the size and shape of the chaff curtain model. It first establishes three-dimensional physical models of the chaff curtain and the detection target, then obtains the node numbers and coordinates of each chaff curtain and detection target surface element through surface subdivision. Subsequently, the chaff curtain and detection target surface elements are merged, fully considering the differences in their brightness temperature calculation methods and ray tracing processes, to achieve joint simulation of the millimeter-wave radiation images of the chaff curtain and the detection target. By jointly simulating the millimeter-wave radiation images of the chaff curtain and the detection target, the interaction between their millimeter-wave radiation is studied, and the impact of the chaff curtain on the detection of the target's millimeter-wave radiation is analyzed, providing a basis for the detection of the target. Attached Figure Description
[0048] Figure 1 A flowchart illustrating a method for jointly simulating millimeter-wave radiation images of a chaff screen and a detection target, provided in an embodiment of the present invention;
[0049] Figure 2(a) and Figure 2(b) are schematic diagrams of the three-dimensional model of the foil curtain and the zenith angle and azimuth angle of a single foil strip, respectively;
[0050] Figure 3 This is a schematic diagram of a two-dimensional planar model of an adaptive foil curtain.
[0051] Figure 4 This is a schematic diagram of a ray incident on a foil screen element.
[0052] Figure 5 This is a schematic diagram showing the reflection of rays from the target surface element onto the foil screen surface element.
[0053] Figures 6(a) and 6(b) are respectively millimeter-wave radiation images of the detection target and joint simulation images of the foil screen and millimeter-wave radiation of the detection target provided by the present invention. Detailed Implementation
[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0055] See Figure 1 This embodiment provides a method for joint simulation of millimeter-wave radiation images of a chaff screen and a detection target, including operations S1 to S6.
[0056] Operation S1 establishes three-dimensional physical models of the chaff screen and the detection target, respectively.
[0057] In this embodiment, a three-dimensional physical model of a foil strip curtain with a certain shape, size and density distribution is established, as shown in Figure 2(a). Based on the distribution function and physical dimensions of the foil strip curtain, a set of three-dimensional data is generated, and each three-dimensional coordinate represents the location of a foil strip.
[0058] Operation S2 divides the three-dimensional physical model of the target into surface elements and obtains the node number and node coordinates of each surface element of the target.
[0059] In this embodiment, the target surface element is a triangular surface element.
[0060] Operation S3 divides the three-dimensional physical model of the foil curtain into multiple sub-blocks, and calculates the average current and effective dielectric constant of each sub-block based on the zenith angle, azimuth angle and length of each foil strip in the sub-block.
[0061] In this embodiment, the three-dimensional physical model of the foil curtain is divided into multiple sub-blocks. Based on the foil direction distribution function W(θ,φ), each foil strip is assigned a zenith angle θ and an azimuth angle φ, as shown in Figure 2(b).
[0062] The average current and effective dielectric constant of each sub-block are calculated based on the zenith angle, azimuth angle and length of each foil strip in the sub-block, specifically including sub-operations S31 to S33.
[0063] In sub-operation S31, the actual current component of the foil is calculated using the method of moments based on the zenith angle θ, azimuth angle φ, and length L of the foil.
[0064]
[0065] In sub-operation S32, the current component The average current I of the foil curtain block is calculated using the directional distribution function W(θ,φ). pq :
[0066]
[0067] In sub-operation S33, the effective dielectric constant ε of each sub-block is calculated using the average current. pq (p, q are θ or φ):
[0068]
[0069] Where W(θ,φ) is the directional distribution function of the foil, Z is the impedance matrix of the foil, T represents the transpose operator, R and V are the measurement vector and excitation vector, respectively, p and q are the zenith angle θ or azimuth angle φ, ε0 is the dielectric constant of air, j is the imaginary part, and η0, ρ, L, and λ represent the intrinsic impedance of free space, the average density of the foil, the length of the foil, and the wavelength in free space, respectively. Free space can be understood as the space without the foil.
[0070] Operation S4: Based on the effective dielectric constants, the three-dimensional physical model of the foil curtain is equivalent to a two-dimensional plane, and the emissivity, reflectivity, and transmittance of each sub-plane on the two-dimensional plane are obtained; then, the two-dimensional plane is divided into surface elements to obtain the node number and node coordinates of each foil curtain surface element.
[0071] In this embodiment, operation S4 specifically includes sub-operations S41 to S43.
[0072] In suboperation S41, the three-dimensional model is equivalent to a two-dimensional plane using the reflection and transmission theory of the field in a multilayer medium based on the effective dielectric constant. The reflection coefficient R and transmission coefficient T of each subplane on the two-dimensional plane are calculated, and the emissivity e, reflectivity Γ, and transmittance Υ of each subplane on the two-dimensional plane are given.
[0073] Γ=|R| 2
[0074]
[0075] e = 1 - Γ - Υ
[0076] Where, η t η is the inherent impedance in the transmission layer. t =η0.
[0077] In sub-operation S42, a two-dimensional plane (0, y, z) is taken from the three-dimensional model (x, y, z) of the foil curtain, and this two-dimensional plane is divided into the following... Figure 3 For the triangular element shown, if column j of the triangular element is even, then the node numbers of the three vertices of the triangular element are as follows:
[0078] v1=i+n×[j / 2], v2=i+n×[j / 2]+1, v3=i+n×([j / 2]+1)
[0079] If column j of the triangular element is odd, then the node numbers of the three vertices of the element are as follows:
[0080] v1=i+n×([j / 2]-1)+1, v2=i+n×[j / 2]+1, v3=i+n×[j / 2]
[0081] where \(i = 1, 2, \ldots, n\), \(j = 1, 2, \ldots, 2m - 2\), \(m\) is the number of divisions on the \(y\)-axis, and \(n\) is the number of divisions on the \(z\)-axis. At the first element in the first column, \(i = 1\) and \(j = 1\), then the node number of this element is \((1, 2, n + 1)\). At the first element in the second column, \(i = 1\) and \(j = 2\), then the node number of this element is \((2, n + 2, n + 1)\). According to the above method, the node numbers of the elements are obtained, and the coordinates of each node number are the same as the coordinates of the 3D model. The emissivity \(e\), reflectivity \(\Gamma\), and transmittance \(\Upsilon\) obtained in sub-operation S41 are corresponding to each triangular element one by one, and the number of elements of the chaff screen is \(N1\).
[0082] In sub-operation S43, the node numbers and node coordinates of the chaff screen and the detection target are merged. After merging, the node coordinates of the chaff screen and the detection target remain unchanged, the node numbers of the detection target remain unchanged, and the node numbers of the chaff screen are:
[0083] Node1(v1,v2,v3) = Node1(v1,v2,v3) + P
[0084] where \(P\) is the number of nodes of the triangular element of the detection target, and the element number is:
[0085] N = [1:N2,N2 + 1:N1 + N2]
[0086] It is determined whether the tracked target is a chaff screen (the number of elements is N1) or a detection target (the number of elements is N2) through the element number N. If \(N > N2\), the tracked element is an element of the chaff screen. If \(N < N2\), the tracked element is a detection target, and \(N2\) is the number of elements of the detection target.
[0087] In operation S5, for each chaff screen element, according to the incident coordinates, incident direction of the ray on the chaff screen element, and the node coordinates of all elements, the tracking path of the ray and the elements intersecting with the tracking path are determined; the brightness temperatures of the elements intersecting with the ray are sequentially determined through reverse tracking, so as to obtain the brightness temperature of each chaff screen element, and the millimeter-wave radiation joint simulation image of the chaff screen and the detection target is output.
[0088] In this embodiment, the differences in the brightness temperature calculation methods of the chaff screen and the detection target and the ray tracing process are fully considered.
[0089] (1) When the ray is incident on the chaff screen element, as Figure 4 shown, the normal vector of the chaff screen element The specific implementation method of brightness temperature calculation is:
[0090] Step 1: Identify the ray ① incident on the chaff screen element in front of the target. Ray ① is reflected by the chaff screen element, and its reflected ray is ②. Determine the number of the screen element and find the emissivity e, reflectivity Γ and transmittance Υ corresponding to the screen element.
[0091] Step 2: Calculate the brightness temperature TB based on the emissivity e, reflectivity Γ, and transmittance Υ of the surface element. (l) :
[0092] TB (l) =e×T0+Γ×T env +Υ×TB (l-1)
[0093] And determine its transmitted ray, and continue to track the surface element that intersects with the transmitted ray. Where l is the current tracking count, T0 is the ambient physical temperature, and T... env For ambient brightness temperature, TB (l-1) This is the brightness temperature after the previous tracking.
[0094] (2) If the rays are reflected onto the foil screen element, such as Figure 5 As shown, the foil screen element normal vector The specific implementation method for brightness temperature calculation is as follows:
[0095] Step 1: Determine the transmitted ray ③ through the foil screen. Ray ③ is reflected by the target surface element, and its reflected ray is ④. When ray ④ is incident on the foil screen surface element in front of the detection target, its transmitted ray is ⑤. Determine the number of the surface element and find the emissivity e, reflectivity Γ and transmittance Υ corresponding to the surface element.
[0096] Step 2: Calculate the brightness temperature TB based on the emissivity e, reflectivity Γ, and transmittance Υ of the surface element. (l) :
[0097] TB (l) =e×T0+Γ×TB (l-1) +Υ×T env
[0098] And determine its reflected ray, and continue to track the surface element that intersects with the reflected ray.
[0099] (3) If the rays are incident on and reflected onto the surface element of the target, calculate its emissivity e and reflectivity Γ and its brightness temperature based on the dielectric constant of the target, and continue to track it according to the traditional calculation method.
[0100] TB (l) =e×T0+Γ×TB (l-1)
[0101] For example, suppose the ray is incident on the foil screen element 1, then transmitted to the detection target element 2, then reflected by the detection target element 2 to the foil screen element 3, and finally transmitted to free space by the foil screen element 3.
[0102] The brightness temperature (TB) of foil screen element 1 (3) for:
[0103] TB (3) =e1×T0+Γ1×T env +Υ1×TB (2)
[0104] TB (2) =e2×T0+Γ2×TB (1)
[0105] TB (1) =e3×T0+Γ3×TB (0) +Υ3×T env
[0106] TB (0) =T env
[0107] Wherein, e1, Γ1 and Υ1 are the emissivity, reflectivity and transmittance of foil screen element 1, respectively; e2 and Γ2 are the emissivity and reflectivity of the detection target element 2, respectively; and e3, Γ3 and Υ3 are the emissivity, reflectivity and transmittance of foil screen element 3, respectively.
[0108] Figures 6(a) and 6(b) show the millimeter-wave radiation image of the target and the joint simulation image of the millimeter-wave radiation of the chaff curtain and the target provided by this invention, respectively. The target is a metal ship on the sea surface. The chaff curtain is uniformly distributed, with a length 1.5 times that of the target, a height 6.5 times that of the target, a thickness of 100 meters, and a density of 75 strips / m². 3 After the target is blocked by the chaff curtain, the brightness temperature at point A changes from 116.6K to 127.7K, and its radiation characteristics change. This invention allows for arbitrary adjustment of the physical size and density distribution of the chaff curtain model according to actual applications. Different targets can be selected, and the relative positions of the chaff curtain and the target can be set. Multiple chaff curtains and targets can be combined to obtain a joint simulation image, providing a basis for analyzing the impact of the chaff curtain on the millimeter-wave radiation detection of the target.
[0109] In summary, this invention enables joint simulation of millimeter-wave radiation images of chaff screens and detection targets.
[0110] This invention divides the chaff curtain into sub-blocks, calculates the actual induced current of the chaff using the method of moments, and calculates the average current of each sub-block based on the directional distribution function of the chaff within it. The effective dielectric constant of each sub-block is then calculated using the average current. The emissivity, reflectivity, and transmittance of each sub-block are then calculated using the reflection and transmission theory of a multilayer medium field based on the effective dielectric constant. Adaptive planar models of chaff curtains of different sizes and densities are obtained. These models are then merged with the target model, and two brightness temperature calculation methods are introduced into the ray tracing. Considering the interaction between the chaff curtain and the target, a joint simulation of their millimeter-wave radiation images is achieved.
[0111] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for joint simulation of millimeter-wave radiation images of chaff screens and detection targets, characterized in that, include: Three-dimensional physical models of the chaff screen and the detection target were established separately; The three-dimensional physical model of the target is divided into surface elements, and the node number and node coordinates of each surface element of the target are obtained. The three-dimensional physical model of the foil curtain is divided into multiple sub-blocks, and the average current and effective dielectric constant of each sub-block are calculated based on the zenith angle, azimuth angle and length of each foil strip in the sub-block. Based on the effective dielectric constants, the three-dimensional physical model of the foil curtain is equivalent to a two-dimensional plane, and the emissivity, reflectivity, and transmittance of each sub-plane on the two-dimensional plane are obtained; then, the two-dimensional plane is divided into surface elements to obtain the node number and node coordinates of each foil curtain surface element. For each foil curtain element, the ray tracking path and the elements intersecting the tracking path are determined based on the incident coordinates and direction of the ray incident on the foil curtain element and the node coordinates of all elements. The brightness temperature of each element intersecting the ray is determined sequentially by reverse tracking, thereby obtaining the brightness temperature of each foil curtain element and outputting a joint simulation image of millimeter-wave radiation of the foil curtain and the detection target.
2. The method for joint simulation of chaff screen and millimeter-wave radiation image of detection target according to claim 1, characterized in that, The calculation of the average current of each sub-block based on the zenith angle, azimuth angle, and length of each foil strip in the sub-block includes: Based on the zenith angle, azimuth angle, and length of each foil strip in the sub-block, the current component of each foil strip is calculated using the method of moments; then, the average current of each sub-block is calculated using the current components and the direction distribution function.
3. The method for joint simulation of chaff screen and millimeter-wave radiation image of detection target according to claim 2, characterized in that, The effective dielectric constant of each sub-block is expressed as: Where p and q are the zenith angle θ or azimuth angle φ, ε0 is the dielectric constant of air, j is the imaginary part, and η0, ρ, L, and λ represent the intrinsic impedance of free space, the average density of the foil, the length of the foil, and the wavelength in free space, respectively. pq The average current of the sub-block.
4. The method for joint simulation of chaff screen and millimeter-wave radiation image of detection target according to claim 1, characterized in that, The step of equating the three-dimensional physical model of the foil curtain to a two-dimensional plane based on the effective dielectric constants of each plane, and obtaining the emissivity, reflectivity, and transmittance of each sub-plane on the two-dimensional plane, includes: Based on the effective dielectric constant and the theory of reflection and transmission in a multilayer medium field, the three-dimensional physical model of the foil curtain is equivalent to a two-dimensional plane, and the reflection coefficient R and transmission coefficient T of each sub-plane on the two-dimensional plane are calculated; the emissivity e, reflectivity Γ, and transmittance Υ of each sub-plane on the two-dimensional plane are expressed as: e = 1 - Γ - Υ, Γ = |R| 2 , Υ=|T| 2 .
5. The method for joint simulation of chaff screen and millimeter-wave radiation image of detection target according to claim 1, characterized in that, The foil strip screen element is a triangular element; If column j of the foil strip element in the two-dimensional plane is even, then the node numbers of the three vertices of the triangular element are as follows: v1=i+n×([j / 2]-1)+1 v2=i+n×([j / 2]+1)+1 v3 = i + n × ([j / 2] + 1) If column j of the foil strip element in the two-dimensional plane is odd, then the node numbers of the three vertices of the triangular element are as follows: v1 = i + n × [j / 2] v2 = i + n × [j / 2] + 1 v3 = i + n × ([j / 2] + 1) Where i = 1, 2, ..., n, j = 1, 2, ..., 2*m-2, m is the number of divisions along the y-axis, n is the number of divisions along the z-axis, and the coordinates of each node number are determined by its actual position and sorted according to the corresponding node number.
6. The method for joint simulation of chaff screen and millimeter-wave radiation image of detection target according to claim 5, characterized in that, Before determining the ray tracking path and the surface elements intersecting the tracking path for each foil screen element based on the incident coordinates and direction of the ray incident on that foil screen element and the node coordinates of all surface elements, the method further includes: Merge the node numbers and node coordinates of all foil screen elements and detection target elements; After merging, the node numbers of the target detection elements remain unchanged, while the node numbers of the foil curtain elements are: Node1(v1,v2,v3)=Node1(v1,v2,v3)+P Where P is the number of surface element nodes of the target being detected.
7. The method for joint simulation of chaff screen and millimeter-wave radiation image of detection target according to claim 1, characterized in that, The step of determining the brightness temperature of each surface element intersecting the ray sequentially by reverse tracing includes: When rays are incident on a foil screen element, the brightness temperature of that foil screen element is expressed as: TB (l) =e1×T0+Γ1×T env +Υ1×TB (l-1) In the formula, e1, Γ1, and Υ1 are the emissivity, reflectivity, and transmittance of the foil screen element, respectively; l is the current tracking count; T0 is the ambient physical temperature; and T... env For ambient brightness temperature, TB (l-1) The brightness temperature is the value after the previous tracking. When rays are reflected onto the foil screen element, the brightness temperature of that foil screen element is expressed as: TB (l) =e2×T0+Γ2×TB (l-1) +Υ2×T env In the formula, e2, Γ2, and Υ2 are the emissivity, reflectivity, and transmittance of the foil screen element, respectively; l is the current tracking count; T0 is the ambient physical temperature; and T env For ambient brightness temperature, TB (l-1) The brightness temperature is the value after the previous tracking. When rays are incident on or reflected onto the target surface element, the brightness temperature of that target surface element is expressed as: TB (l) =e3×T0+Γ3×TB (l-1) In the formula, e3 and Γ3 are the emissivity and reflectivity of the detected target surface element, respectively, l is the current tracking count, T0 is the ambient physical temperature, and TB is the ambient temperature. (l-1) This is the brightness temperature after the previous tracking.
8. A joint simulation system for chaff screen and millimeter-wave radiation image of a detection target, characterized in that, include: Computer-readable storage media and processors; The computer-readable storage medium is used to store executable instructions; The processor is used to read executable instructions stored in the computer-readable storage medium and execute the co-simulation method for millimeter-wave radiation images of foil screen and detection target as described in any one of claims 1-7.