An Edge Interface Design Method for Typical Edge RCS Reduction

Abstract

The present invention relates to the field of aerospace technology, and particularly to an edge interface design method for typical edge RCS reduction. The present invention uses a Gaussian surface to shape the edge, constructs a high-order surface through a Gaussian function, changes the original edge shape, thereby reducing the influence of edge scattering. Through formula derivation, the expression of the side contour line of the high-order surface is obtained; then, a model is established according to an example for optimization, and then simulation is carried out. The method of the present invention has good reduction performance for edge scattering within a large angle range under horizontal polarization of electromagnetic waves, and can effectively reduce the edge RCS under horizontal (HH) polarization. The present invention has strong operability, requires little computing resources, is easy to implement, has a wide application prospect in the field of microwave stealth, and is worthy of promotion.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, and particularly relates to an edge interface design method for typical edge RCS reduction, which is optimized based on a Gaussian surface. Background Art

[0002] Stealth technology has become a research focus of major countries in the world. The core of stealth technology is to minimize the RCS of the target as much as possible, thereby reducing the probability of being detected and discovered by the enemy. Stealth technology mainly includes shaping design, the application of radar absorbing materials or radar absorbing structures, active stealth, and passive stealth. With the development of stealth technology, the application of shaping design and radar absorbing materials, strong scattering edges such as specular reflection and corner reflectors have been effectively controlled, and the scattering control of surface electromagnetic defects such as edges has become an urgent problem to be solved in current stealth technology. Moreover, the edge is an inevitable component part of the target and the electromagnetic scattering or radiation test platform. Therefore, the control of edge scattering has become a key point in the development of current stealth technology.

[0003] With the development of edge stealth structures, loading edge stealth structures to effectively control edge scattering is the main method for repairing current and future edge-like surface electromagnetic defects. The interfaces introduced by loading edge stealth structures must be shaped and optimized to meet the perfect matching among the edge carrier, the interface, and the edge stealth structure.

[0004] The methods for controlling edge scattering are mainly carried out through shaping and loading absorbing materials. Among them, the shaping method is the simplest and most direct, which can directly control the edge scattering effect from the scattering state. By adjusting the edge shape, the RCS of the edge can be effectively reduced. The edge serration technology is an important case of edge shaping design. With the development and application of edge stealth structures, the edge part can effectively control edge scattering through loading stealth structures. However, when loading edge stealth structures, there will inevitably be interface problems with the target carrier. The optimized design of the interface shape is a key point to ensure the edge scattering control ability of the edge stealth structure and is conducive to the effective repair of edge-like surface electromagnetic defects.

[0005] The existing typical interface optimization is the edge of the wedge-shaped interface. In the design of the interface edge, the goal is to make the edge RCS value as small as possible, but it has the problems of low parameter flexibility and relatively limited RCS reduction effect. Summary of the Invention

[0006] Aiming at the above existing problems or deficiencies, in order to solve the problems of low parameter flexibility and poor RCS reduction effect in the existing interface edge design, the present invention provides an edge interface design method for typical edge RCS reduction, which is optimized based on the Gaussian function surface.

[0007] A method for edge interface design for typical edge RCS reduction, comprising the following steps:

[0008] Step 1: First, give the basic Gaussian distribution function:

[0009]

[0010] where is the peak value, μ is the distribution mean, σ is the standard deviation, x is the function independent variable, π is the ratio of the circumference of a circle to its diameter, and e is the base of the natural logarithm function.

[0011] For derivation to a more general case, the generalized one-dimensional Gaussian function can be written as:

[0012]

[0013] where h, b, c, and d are the fixed parameters of the function, which determine the shape and position of the function image in the coordinate axes.

[0014] Step 2: Give the starting point coordinates of the edge side contour line and the tangent slope at the position of the starting point:

[0015] 1) The starting point is the coordinate origin (0, 0), and the tangent slope k 0 .

[0016] 2) The ending point is (L, -h 0 ), and the tangent slope k 1 .

[0017] where L represents the horizontal length of the contour line, h 0 represents the vertical height of the contour line, k 0 is determined by the tangent slope at the connection with the starting point in the actual situation, and k 1 is determined by the tangent slope at the ending point.

[0018] The derivative function of equation (2) is:

[0019]

[0020] The probability density of the contour line equation in the starting point interval is:

[0021]

[0022] Substituting the initial conditions in 1) and 2) into equations (2) and (3), we can obtain:

[0023]

[0024] Step 3: Simplifying the system of equations in equation (5) in Step 2, we can get:

[0025]

[0026]

[0027]

[0028]

[0029] The value of d can be obtained through Equation (6). Substituting d into Equation (7), the value of c can be obtained. Substituting d and c into Equation (8), the values of h and b can be obtained. Thus, all unknowns are solved, and the complete expression of Equation (2) and the probability density of Equation (4) can be obtained.

[0030] Step 4: After obtaining the complete expression, the curve expression can be input according to the starting point in the modeling software to obtain the side contour line of the surface, and then the complete Gaussian surface can be established by stretching the contour line.

[0031] Step 5: Replace the original edge surface with the Gaussian surface established in Step 4, and obtain the changed edge RCS through simulation.

[0032] Furthermore, to obtain better results, the parameters L, h 0 , k 0 and k 1 of the actual model can be adjusted to control the four parameters h, b, c, and d in the Gaussian function expression, thereby changing the probability density occupied by the side contour of the Gaussian surface, and optimizing it to obtain a Gaussian edge surface with a lower RCS.

[0033] The present invention constructs a high-order surface by using a Gaussian function, changes the original edge shape, thereby reducing the influence of edge scattering. Through formula derivation, the expression of the side contour line of the high-order surface is obtained, and then the model is established and optimized according to the example, and then simulation is carried out, and it is verified that this method has good reduction performance for edge scattering in a large angle range under horizontal polarization of electromagnetic waves.

[0034] In summary, the present invention uses a Gaussian surface to shape the edge, thereby reducing the edge scattering effect, and an optimal solution under application requirements can be obtained by optimizing relevant parameters. Through simulation and actual measurement in application, it can be seen that the designed and optimized interface edge using the present invention can effectively reduce the edge RCS under horizontal (HH) polarization. The present invention provides a new optimization design scheme for reducing the edge RCS; and has higher parameter flexibility and better RCS reduction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the principle of the typical edge structure model for loading the Gaussian surface in the embodiment;

[0036] Figure 2 Schematic diagram of the three-dimensional structure of the typical edge model of the Gaussian surface loaded for the embodiment;

[0037] Figure 3 Simulation result diagram of the edge RCS of the Gaussian surface loaded for the embodiment when varying with the transverse length and the operating frequency;

[0038] Figure 4 Simulation result diagram of the edge RCS of the Gaussian surface loaded for the embodiment when varying with the transverse length and the operating frequency;

[0039] Figure 5 Simulation result diagram of the edge RCS of the Gaussian surface loaded for the embodiment when varying with the transverse length and the end angle;

[0040] Figure 6 Simulation result diagram of the edge RCS of the Gaussian surface loaded for the embodiment when varying with the transverse length and the end angle;

[0041] Figure 7 Schematic diagram of the model of the typical edge loaded with the Gaussian surface or the traditional wedge surface and the gradient impedance material for the embodiment;

[0042] Figure 8 RCS simulation results of the sample typical edge structure in different states at 0.3 GHz under horizontal polarization for the embodiment;

[0043] Figure 9 Description of the relevant parameter range and simulation state of the Gaussian surface for the embodiment. Detailed implementation manners

[0044] The following further describes the present invention in detail with reference to the accompanying drawings and embodiments.

[0045] Embodiment

[0046] In this embodiment, for the edge, a method of loading with a gradient impedance absorbing material is adopted. By changing the interface shape, that is, comparing the edge RCS characteristics in the cases where the interface shape is a traditional wedge surface and a Gaussian surface under the same material loading. The sample model is as Figure 7 shown. From left to right are the typical edge metal structure, the edge structure loaded with the traditional wedge surface / gradient impedance absorbing material, and the edge structure loaded with the Gaussian surface / gradient impedance absorbing material.

[0047] An edge interface design method for typical edge RCS reduction includes the following steps:

[0048] Step 1. The one-dimensional Gaussian function expression of the Gaussian surface edge side contour line is:

[0049]

[0050] Among them, h, b, c, and d are fixed parameters of the function, which determine the shape of the function graph;

[0051] These four fixed parameters can be calculated through the following equations:

[0052]

[0053]

[0054]

[0055]

[0056] According to Figure 1 as shown, we can determine the lateral length L and longitudinal height h of the model variable parameters 0 , and the included angle 2α at the end point. Then we can obtain:

[0057] k 1 = -tan(α) (5)

[0058] According to Figure 9 , the tangent line at the fixed starting point is in a horizontal state, that is:

[0059] k 0 = 0 (6)

[0060] Substitute the above model variable parameters into the calculation formula to obtain the complete expression of the side contour line of the Gaussian surface.

[0061] Step 2: According to the expression calculated in Step 1, an entity model can be established in the modeling software. For the lateral length L and longitudinal height h of the model variable parameters 0 being determined, by changing the value of the included angle 2α at the end point, different contour line expressions can be obtained, thereby establishing different Gaussian surfaces. By simulating different models, the change of the RCS value of the model can be obtained.

[0062] Partial results are shown in Figures 3 to 6 : In the figure, A2 represents the included angle at the end point, which is the same as 2α. Freq represents the simulation frequency. Pol = 0 represents that the polarization state of the electromagnetic wave is horizontal polarization (HH), and Pol = 90 represents that the polarization state of the electromagnetic wave is vertical polarization (VV). MHz is the frequency unit, mm is the length unit, and Deg is the angle unit.

[0063] Figure 3 It is the simulation result diagram of the edge RCS of the loaded Gaussian surface with the change of the lateral length and working frequency under the irradiation of horizontally polarized electromagnetic waves for the pure metal structure in the embodiment. Among the attached figures, the included angle at the end point of the Gaussian surface is different.

[0064] Figure 4 For the simulation result diagram of the edge RCS of the loaded Gaussian surface with the change of the transverse length and the operating frequency under the irradiation of vertically polarized electromagnetic waves in the pure metal structure for the embodiment, where the included angle between the end points of the Gaussian surface is different between the attached drawings.

[0065] Figure 5 For the simulation result diagram of the edge RCS of the loaded Gaussian surface with the change of the transverse length and the included angle at the end point under the irradiation of horizontally polarized electromagnetic waves in the pure metal structure for the embodiment, where the operating frequency is different between the attached drawings.

[0066] Figure 6 For the simulation result diagram of the edge RCS of the loaded Gaussian surface with the change of the transverse length and the included angle at the end point under the irradiation of vertically polarized electromagnetic waves in the pure metal structure for the embodiment, where the operating frequency is different between the attached drawings.

[0067] It can be seen from the figure that the design method of the present invention has a better effect on horizontal polarization. By gradually optimizing the model variable parameters, the optimal solution under the requirements can be obtained.

[0068] Step 3: After obtaining the complete optimized expression of the side contour line of the Gaussian surface, establish an example model, as Figure 7 shown in the right figure. Figure 7 For the schematic diagram of the model under the loading of the Gaussian surface or the traditional wedge surface and the gradient impedance material for the typical edge of the embodiment. From left to right, they are the typical edge metal structure, the edge structure loaded with the traditional wedge surface / gradient impedance absorbing material, and the edge structure loaded with the Gaussian surface / gradient impedance absorbing material.

[0069] Step 4: Perform simulation calculations on the established model to obtain the simulation data of the edge RCS of the model at 0.3 GHz of electromagnetic waves and horizontal polarization; as Figure 8 shown, it can be seen that in the range of 0 - 45°, compared with the traditional wedge surface interface, the edge RCS reduction effect of the Gaussian surface interface is better, verifying the effectiveness of the design method.

[0070] In summary, the present invention designs an edge stealth structure interface using the Gaussian function, thereby achieving the reduction of the target edge RCS. It is also possible to further improve the edge scattering state by optimizing relevant parameters to change the probability density of the side contour of the Gaussian surface. Through specific embodiments, it is confirmed that the edge stealth structure of the Gaussian surface interface optimized and designed based on the method of the present invention has a lower RCS value in a large angle range compared with the traditional wedge-shaped surface interface. Through relevant experimental tests, the effectiveness of the method of the present invention is also verified, which can effectively reduce the RCS of the edge structure, providing a new design and optimization idea for edge RCS reduction; moreover, the present invention has strong operability, requires small computing resources, is easy to implement, and has a wide application prospect in the field of microwave stealth and is worthy of promotion.

Claims

1. An edge interface design method for typical edge RCS reduction, It is characterized in that The following steps are involved: Step 1: First, give the basic Gaussian distribution function: where is the peak value, μ is the distribution mean, σ is the standard deviation, x is the independent variable of the function, π is the ratio of a circle's circumference to its diameter, and e is the base of the natural logarithm function; To derive to a more general case, the generalized one-dimensional Gaussian function can be written as: Among them, h, b, c, and d are fixed parameters of the function, which determine the shape and position of the function graph in the coordinate axis; Step 2: Give the coordinates of the starting point of the edge side contour line and the tangent slope at the starting point: 1) The starting point is the coordinate origin (0, 0), and the slope of its position tangent line is k 0 ; 2) The end point is (L, -h 0 ), and the slope k of its position tangent line 1 ; where L represents the horizontal length of the contour line, h 0 represents the vertical height of the contour line, k 0 is determined by the tangent slope at the connection point with the starting point in the actual situation, k 1 is determined by the tangent slope where the end point is located; The derivative function of formula (2) is: The probability density of the contour line equation within the starting point interval is: Substituting the initial conditions in 1) and 2) into equations (2) and (3), we can obtain: Step 3: Simplify the equation group (5) in step 2 to obtain: By using formula (6), we can get d. Substituting d into formula (7) can get c. Substituting d and c into formula (8) can get the values ​​of h and b. At this point, all unknowns have been obtained, and the complete expression of formula (2) and the probability density of formula (4) can be obtained. Step 4: After obtaining the complete expression, you can enter the curve expression according to the starting point in the modeling software to obtain the side contour line of the surface, and then build a complete Gaussian surface by stretching the contour line; Step 5: Replace the original edge surface with the Gaussian surface created in step 4, and obtain the changed edge RCS through simulation.

2. The edge interface design method for typical edge RCS reduction as claimed in claim 1, Features: By adjusting the parameters L and h of the actual model 0 , k 0 and k 1 to control the four parameters h, b, c, and d in the Gaussian function expression, thereby changing the probability density occupied by the side contour of the Gaussian surface, and optimizing to obtain a Gaussian edge surface with a lower RCS.

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