Method for extracting supersonic target RCS (radar cross section) characteristics under terahertz wave band
Through the FEKO-based RCS characteristic detection method, a simulation model of supersonic targets was established and a plasma sheath model was added, which solved the problem that it was difficult to accurately detect supersonic target RCS in the terahertz band in the existing technology, and achieved the problem of supersonic targets in the terahertz band RCS feature extraction and stealth performance evaluation.
Patent Information
- Application Number
- CN202411877721.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-02-14
AI Technical Summary
The existing RCS characteristic detection methods are difficult to accurately detect and analyze the RCS of supersonic targets, especially in the terahertz band, and there is a lack of optimized design for the characteristics of supersonic targets.
Using the FEKO-based RCS characteristic detection method, a simulation model of supersonic target was established, and static and dynamic characteristics were analyzed, and a plasma sheath model was added on this basis to perform RCS characteristic extraction.
The RCS characteristic extraction of supersonic targets in the terahertz band is achieved, providing a more accurate stealth performance evaluation, and improving the stealth effect of supersonic targets.
Smart Images
Figure CN119439113A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of electromagnetic scattering, and in particular relates to a method for extracting RCS characteristics of a supersonic target in a terahertz band. Background Art
[0002] Radar cross section (RCS) is an important parameter for evaluating the target's ability to reflect radar waves, which directly affects the target's visibility in radar detection and tracking. RCS characteristic detection aims to evaluate the target's ability to reflect radar waves, thereby determining the target's visibility on the radar screen. Existing RCS characteristic detection methods have certain limitations. On the one hand, traditional RCS characteristic detection methods usually rely on theoretical models or large-scale experimental equipment, which are costly and difficult to meet the needs of high-speed movement; on the other hand, existing FEKO-based RCS detection methods often lack optimized designs for the characteristics of supersonic targets, making it difficult to accurately detect and analyze the RCS of supersonic targets.
[0003] In recent years, with the rise of terahertz technology, the RCS characteristics of targets in the terahertz band have attracted more and more interest. Terahertz (THZ) waves usually refer to electromagnetic waves with frequencies between 0.1THZ-10THZ (corresponding to wavelengths of 30m-3mm), which are between millimeter waves and infrared light. Due to the high frequency of terahertz waves and the lack of effective terahertz radiation and detection methods, people's understanding of this band is very limited. Terahertz has also become the last frequency window in the electromagnetic spectrum that has not been fully studied and utilized, known as the "terahertz gap". With the breakthrough of terahertz sources, detection and related devices, a series of superior properties of terahertz waves such as large bandwidth, high resolution and good penetration have been discovered, showing broad application prospects in the fields of space surveillance and flight target early warning. Terahertz radar systems have begun to emerge. Accurately and quickly predicting the RCS of targets in the terahertz band is imminent. At present, the RCS measurement system in the terahertz band is not yet mature, so calculating the RCS in the terahertz band through theoretical methods and software is the main means and preferred method for studying target characteristics. Among the mainstream electromagnetic calculation software, FEKO and CST are widely used, and their RCS calculation performance in the microwave band has been fully verified.
[0004] Therefore, in response to the above problems, we conducted a study on the RCS characteristic detection method based on FEKO in the terahertz frequency band, aiming to develop an efficient and accurate RCS detection method for supersonic targets, so as to improve the survivability and combat effectiveness of supersonic targets in complex electromagnetic environments. Finite element analysis (FEA) is a numerical analysis method widely used in the engineering field, and the electromagnetic field simulation software FEKO based on FEA has become one of the important tools for RCS characteristic research. FEKO can accurately simulate the electromagnetic response of the target structure and calculate the RCS characteristics of the target, providing effective tools and methods for the stealth design of supersonic targets and detecting enemy targets. Our research will use FEKO software to model and simulate the structure of supersonic targets, and combine optimization algorithms and numerical analysis methods to conduct comprehensive and accurate detection and analysis of the RCS characteristics of supersonic targets. Through this method, we will be able to accurately evaluate the stealth performance of supersonic targets, provide strong support for the design and improvement of supersonic targets, and promote the progress and development of supersonic target technology. Summary of the invention
[0005] In order to solve the above technical problems, the present invention provides a method for extracting RCS characteristics of a supersonic target in the terahertz band, comprising the following steps:
[0006] Step 1, establishing a simulation model of a supersonic target;
[0007] Step 2, analyzing and testing the static characteristics of the supersonic target model;
[0008] Step 3, analyzing and testing the dynamic characteristics of the supersonic target model;
[0009] Step 4: Modeling of plasma sheath model;
[0010] Step 5: Analyze and test the plasma sheath model.
[0011] Furthermore, step 2 includes the following steps:
[0012] S2.1, import the model file created in step 1 into FEKO software;
[0013] S2.2, setting parameters of the model file imported into FEKO software, wherein the parameters include frequency, wavelength, solution method, incident wave, and polarization mode;
[0014] S2.3, meshing the supersonic target simulation model after setting parameters;
[0015] S2.4. Extract static RCS characteristics and solve them using FEKO software. After the solution is completed, check the results.
[0016] Further, step 3 includes the following steps:
[0017] S3.1. After setting parameters and dividing the grid, enter the editing module of FEKO software to add the variables that need to be controlled;
[0018] S3.2. After adding the control variables, control the direction of the motion change through the coordinate axis. After the setting is completed, save the content edited in the editing module and exit the editing module of the FEKO software;
[0019] S3.3, in MATLAB software, using code to control the variables to change, and realizing the dynamic change of the model through joint simulation of MATLAB software and FEKO software;
[0020] S3.4. After the simulation of static RCS characteristics and dynamic RCS characteristics is completed, enter the post-processing module of FEKO software, view the obtained RCS characteristic results, create a two-dimensional graph of the far field, and extract the obtained RCS characteristic curve.
[0021] Furthermore, in step 4, based on the simulation model of the supersonic target established in step 1, a plasma sheath model is added to the outer layer.
[0022] Further, step 5 includes the following steps:
[0023] S5.1. Import the established plasma sheath model into FEKO software to set parameters, wherein the parameters include frequency, wavelength, solution method, incident wave and polarization mode;
[0024] S5.2. On the basis of the established plasma sheath model, parameters of the outer plasma sheath are set, wherein the parameters of the plasma sheath include dielectric constant, loss tangent and magnetic permeability;
[0025] S5.3, meshing the simulation model with the plasma sheath after setting the parameters and the plasma sheath parameters;
[0026] S5.4. After the RCS characteristic simulation of the plasma sheath model is completed, enter the post-processing module of the FEKO software to view the obtained RCS characteristic results, create a two-dimensional graph of the far field, and extract the obtained RCS characteristic curve.
[0027] Furthermore, in step 1, six different supersonic target models of two types, axisymmetric and waverider, are modeled and analyzed respectively. The six different supersonic target models include a cone model, a cone model with a tail, a waverider model 1, a waverider model 2, a waverider model with a tail and a single type of waverider model, wherein the waverider model 1 has no small tail, and the waverider model 2 has a small tail.
[0028] Furthermore, in step 2, the frequency of the extracted supersonic target is carried out in the terahertz band, and the RCS characteristics of the established supersonic target model are extracted for the static, dynamic and plasma sheath-covered target models at four frequencies of 94 GHz, 220 GHz, 340 GHz and 850 GHz, respectively.
[0029] Furthermore, in step 4, an axisymmetric model and a waverider model are selected to model the plasma sheath model, and a single-layer plasma sheath model and a double-layer plasma sheath model are established respectively. For the double-layer plasma sheath model, two different parameters are set for the first and second layers respectively to simulate plasma sheath models with different numbers of layers.
[0030] Compared with the prior art, the present invention has the following beneficial effects:
[0031] The present invention utilizes the strong penetrating performance of terahertz waves to extract the RCS characteristics of supersonic target models in different forms and states in the terahertz band. By utilizing the present invention, it is possible to provide a more valuable reference for the extraction of dynamic and static characteristics of supersonic targets during flight in the air, so as to facilitate further optimization of the design of supersonic targets and greatly improve the stealth effect of supersonic targets. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 It is a flow chart of the overall steps in the implementation process of the present invention;
[0033] Figure 2 These are six types of supersonic target model diagrams during the implementation of the present invention, wherein (a) is a cone model, (b) is a cone model with a tail wing, (c) is a waverider model 1, (d) is a waverider model 2, (e) is a waverider model with a tail wing, and (f) is a single type of waverider model. DETAILED DESCRIPTION
[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0035] A specific embodiment of the present invention provides a method for extracting RCS characteristics of supersonic targets based on FEKO in the terahertz band, which includes establishing different types of supersonic target models and extracting their static RCS characteristics and dynamic RCS characteristics in the terahertz band respectively; at the same time, a target model with a plasma sheath is further established for the established supersonic target model, and its RCS characteristics are extracted. The detailed implementation method is as follows:
[0036] S1. Establish a simulation model of supersonic targets
[0037] Due to the particularity of the research object, its detailed data is not available, and the model can only be designed with a model similar to the actual supersonic target. After the modeling is completed, the model is exported as a .stp file, which is convenient for subsequent import into the FEKO software for further simulation testing. In the present invention, six types of supersonic target models of two types, axisymmetric model and waverider model, are established according to the needs. The models are as follows Figure 2 The six models are a cone model, a cone model with tail fins, two waverider models 1 and 2 with slight differences in the tail. The difference between the two waverider models lies in the tail of the warhead. Waverider model 1 does not have a small tail fin, while waverider model 2 has a small tail fin, a waverider model with tail fins, and a single type of waverider model.
[0038] S2. Analyze and test the static characteristics of the supersonic target model
[0039] For the six supersonic target models established in S1, the static RCS characteristics of different supersonic target models at four frequencies of 94GHz, 220GHz, 340GHz, and 850GHz are extracted in FEKO. The static RCS characteristics mainly focus on the shape, material, and surface electromagnetic properties of the target, without considering the Doppler effect caused by the target motion. These factors jointly determine the reflection intensity of the target within a specific frequency range, which directly affects the stealth performance of the target. By studying the static RCS characteristics of supersonic targets, it is possible to further optimize their appearance, materials, etc. during the design process. By reasonably designing the electromagnetic parameters of the target surface, the RCS can be controlled, thereby reducing the possibility of radar detection. Specifically, this step contains 4 sub-steps:
[0040] S2.1. Import the established model file into FEKO software
[0041] Import the model file that has been established in S1 into FEKO so that the meshing and parameter setting can be performed for the subsequent simulation.
[0042] S2.2. Setting parameters for the model
[0043] The model imported into FEKO is parameterized, including the frequency, wavelength, solution method, incident wave, polarization mode, etc. In this example, the RCS characteristics are simulated and analyzed at four frequencies: 94 GHz, 220 GHz, 340 GHz, and 850 GHz.
[0044] S2.3. Grid Division
[0045] For the supersonic target simulation model with set parameters, we need to mesh it. Meshing is the key to subsequent solution. The quality of meshing affects the results of subsequent simulation. Poor mesh quality will affect the accuracy of subsequent simulation results. Too dense meshing will require a lot of memory for calculation during the solution process, which requires high computer performance and is very time-consuming.
[0046] S2.4. Static RCS feature extraction
[0047] For the extraction of static RCS characteristics, after setting the parameters and dividing the grid, you can directly use the FEKO software to set the solution algorithm and method to solve it, and then check the results after the solution is completed.
[0048] S3. Analyze and test the dynamic characteristics of the supersonic target model
[0049] On the basis of the static RCS characteristic test, the dynamic RCS characteristics of 6 different supersonic target models are further extracted. For the extraction of dynamic RCS characteristics, it is necessary to use the joint simulation of MATLAB and FEKO, and modify the parameters set in the FEKO model by running the MATLAB code to control the changes of the supersonic target model. The present invention mainly involves the height change and angle change of the supersonic target model, and simulates the dynamic changes of the supersonic target during the flight process by controlling the different changes in height and angle.
[0050] For the extraction of dynamic RCS characteristics, after setting the frequency, wavelength, solution method, incident wave, polarization mode and other parameters and dividing the grid, further processing is required to realize the dynamicization of the model. This step includes 4 sub-steps:
[0051] S3.1. Adding control variables
[0052] After setting the parameters and dividing the grid, enter the editing module of the FEKO software and add the variables that need to be controlled. In this example, two variables, angle alpha and height high, are added. Their initial values are 0, which can control the angle change and height change of the target model respectively.
[0053] S3.2. Determine the control method
[0054] After adding the control variable, you can control the direction of its movement through the coordinate axis. In this example, the height of the target model moving upward along the Z axis is controlled by the variable high, and the angle change is the angle alpha of the target model rotating along the Y axis. After the setting is completed, save the content edited in the editing module and exit the FEKO editing module.
[0055] S3.3、MATLAB code control changes
[0056] In MATLAB software, the variables designed above are controlled by code to change, and the dynamic change of the model is realized through the joint simulation of MATLAB software and FEKO software. In the MATLAB source program, the designed variables can be controlled by code, as well as the number of movements during the change process. By modifying the values of the variables set in the editing module of FEKO software through the source program code, the position and state of the target model in different situations can be obtained.
[0057] S3.4. View the results
[0058] After the above static RCS and dynamic RCS characteristics simulations are completed, enter the FEKO post-processing module to view the RCS characteristic results, create a two-dimensional graph of the far field, and extract the obtained RCS characteristic curve.
[0059] S4. Modeling of plasma sheath model
[0060] During the flight of a supersonic target, due to its high speed, it will collide with the atmosphere to ionize plasma in the process of re-entering the atmosphere after ascending flight, and the plasma will be wrapped around the outside of the supersonic target, thereby forming a plasma sheath. Due to the existence of the plasma sheath, a black barrier area will be formed in the supersonic target during the flight, and it is difficult to monitor its trajectory, which will cause certain difficulties for the defense of the enemy target. Due to its higher frequency, terahertz waves can have better penetration, which can alleviate the existing black barrier problem to a certain extent, and is currently highly concerned by researchers. In view of the above problems, the present invention also takes it into consideration, selects an axisymmetric model and a waverider model to model its plasma sheath model, and establishes a single-layer plasma sheath model and a double-layer plasma sheath model for testing in the terahertz band.
[0061] This example also involves the extraction of RCS characteristics of the plasma sheath model, so it is necessary to model the plasma sheath model to facilitate the subsequent analysis and extraction of RCS characteristics. In this example, a common conical warhead model and a waverider warhead model were selected as the basis, and the models after adding the plasma sheath were modeled respectively.
[0062] (1) Modeling of supersonic target
[0063] The basic supersonic target model is modeled in FEKO software or other similar simulation software. In this example, a common cone model and a waverider model are modeled. After the modeling is completed, the basic model is saved.
[0064] (2) Plasma sheath modeling
[0065] On the basis of the well-modeled basic model, it is necessary to add a plasma sheath model to its outer layer. The plasma sheath model is modeled as a layer covering the outside of the model. In this example, the RCS characteristics of the single-layer plasma sheath model and the double-layer plasma sheath model of the cone model and the waverider model are extracted respectively. Therefore, the models of the single-layer and double-layer plasma sheaths are established on the basis of the original basic model.
[0066] S5. Analyze and test the plasma sheath model
[0067] Based on the single-layer plasma sheath model and double-layer plasma sheath model established by S4, the RCS characteristics at four different frequencies of 94 GHz, 220 GHz, 340 GHz and 850 GHz were extracted respectively.
[0068] Specifically, this step contains 4 sub-steps as follows:
[0069] S5.1. Setting parameters for the plasma sheath model
[0070] Import the established single-layer or double-layer plasma sheath model into FEKO to set parameters, just like the static and dynamic extraction of RCS characteristics, including the setting of its frequency, wavelength, solution method, incident wave, polarization mode and other parameters. In this example, the RCS characteristics are simulated and analyzed at four frequencies: 94GHz, 220GHz, 340GHz and 850GHz.
[0071] S5.2. Setting plasma sheath parameters for the plasma sheath model
[0072] On the basis of the established single-layer or double-layer plasma sheath model, it is necessary to set the parameters of the outer plasma sheath, and simulate the plasma sheath formed in reality by setting the dielectric constant, loss tangent, magnetic permeability and other parameters of the sheath model. For the double-layer plasma sheath model, it is necessary to set two different parameters for the first and second layers respectively to simulate the plasma sheath models with different numbers of layers.
[0073] S5.3. Grid Division
[0074] For the simulation model with plasma sheath with set parameters and plasma sheath parameters, it is also necessary to mesh it like the basic model. The meshing requirements are the same as mentioned above, and both performance and simulation speed requirements need to be balanced.
[0075] S5.4. View the results
[0076] After the RCS characteristic simulation of the above-mentioned single-layer or double-layer plasma sheath model is completed, the RCS characteristic results obtained are viewed in the post-processing module of FEKO, a two-dimensional graph of the far field is created, and the obtained RCS characteristic curve is extracted.
[0077] The method can conveniently and accurately extract the RCS characteristics of supersonic targets. The invention conducts detailed analysis and testing on the supersonic target model at four frequencies of 94GHz, 220GHz, 340GHz and 850GHz to extract the RCS characteristics of supersonic targets at different frequencies.
[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, several modifications and improvements may be made without departing from the principle of the present invention, and these should also be regarded as falling within the scope of protection of the present invention.
Claims
1. A method for extracting RCS characteristics of supersonic targets in the terahertz band, characterized in that: The following steps are involved: Step 1, establishing a simulation model of a supersonic target; Step 2, analyzing and testing the static characteristics of the supersonic target model; Step 3, analyzing and testing the dynamic characteristics of the supersonic target model; Step 4: Modeling of plasma sheath model; Step 5: Analyze and test the plasma sheath model.
2. The method for extracting RCS characteristics of a supersonic target in the terahertz band according to claim 1, characterized in that: Step 2 includes the following steps: S2.1, import the model file created in step 1 into FEKO software; S2.2, setting parameters of the model file imported into FEKO software, wherein the parameters include frequency, wavelength, solution method, incident wave, and polarization mode; S2.3, meshing the supersonic target simulation model after setting parameters; S2.
4. Extract static RCS characteristics and solve them using FEKO software. After the solution is completed, check the results.
3. The method for extracting RCS characteristics of a supersonic target in the terahertz band according to claim 2, characterized in that: Step 3 includes the following steps: S3.
1. After setting parameters and dividing the grid, enter the editing module of FEKO software to add the variables that need to be controlled; S3.
2. After adding the control variables, control the direction of the motion change through the coordinate axis. After the setting is completed, save the content edited in the editing module and exit the editing module of the FEKO software; S3.3, in MATLAB software, using code to control the variables to change, and realizing the dynamic change of the model through joint simulation of MATLAB software and FEKO software; S3.
4. After the simulation of static RCS characteristics and dynamic RCS characteristics is completed, enter the post-processing module of FEKO software, view the obtained RCS characteristic results, create a two-dimensional graph of the far field, and extract the obtained RCS characteristic curve.
4. The method for extracting RCS characteristics of a supersonic target in the terahertz band according to claim 3, characterized in that: In step 4, based on the simulation model of the supersonic target established in step 1, a plasma sheath model is added to the outer layer.
5. The method for extracting RCS characteristics of a supersonic target in the terahertz band according to claim 4, characterized in that: Step 5 includes the following steps: S5.
1. Import the established plasma sheath model into FEKO software to set parameters, wherein the parameters include frequency, wavelength, solution method, incident wave and polarization mode; S5.
2. On the basis of the established plasma sheath model, parameters of the outer plasma sheath are set, wherein the parameters of the plasma sheath include dielectric constant, loss tangent and magnetic permeability; S5.3, meshing the simulation model with the plasma sheath after setting the parameters and the plasma sheath parameters; S5.
4. After the RCS characteristic simulation of the plasma sheath model is completed, enter the post-processing module of the FEKO software to view the obtained RCS characteristic results, create a two-dimensional graph of the far field, and extract the obtained RCS characteristic curve.
6. The method for extracting RCS characteristics of a supersonic target in the terahertz band according to claim 5, characterized in that: In step 1, six different supersonic target models of two types, axisymmetric and waverider, are modeled and analyzed respectively. The six different supersonic target models include a cone model, a cone model with a tail, a waverider model 1, a waverider model 2, a waverider model with a tail and a single type of waverider model, wherein the waverider model 1 has no small tail, and the waverider model 2 has a small tail.
7. The method for extracting RCS characteristics of a supersonic target in the terahertz band according to claim 6, characterized in that: In step 2, the frequency of the extracted supersonic target is carried out in the terahertz band, and the RCS characteristics of the established supersonic target model are extracted for the static, dynamic and plasma sheath-covered target models at four frequencies of 94 GHz, 220 GHz, 340 GHz and 850 GHz respectively.
8. The method for extracting RCS characteristics of a supersonic target in the terahertz band according to claim 7, characterized in that: In step 4, an axisymmetric model and a waverider model are selected to model the plasma sheath model, and a single-layer plasma sheath model and a double-layer plasma sheath model are established respectively. For the double-layer plasma sheath model, two different parameters are set for the first and second layers respectively to simulate plasma sheath models with different numbers of layers.