CN113281708A - Modeling method for scattering center model of foil strip - Google Patents
Modeling method for scattering center model of foil strip Download PDFInfo
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- CN113281708A CN113281708A CN202110218169.4A CN202110218169A CN113281708A CN 113281708 A CN113281708 A CN 113281708A CN 202110218169 A CN202110218169 A CN 202110218169A CN 113281708 A CN113281708 A CN 113281708A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/40—Means for monitoring or calibrating
- G01S7/4052—Means for monitoring or calibrating by simulation of echoes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/38—Jamming means, e.g. producing false echoes
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
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Abstract
The invention discloses a modeling method of a scattering center model of a foil strip, which comprises the following steps of; the method comprises the following steps: modeling the foil strips and dividing the foil strips by a triangular surface element; step two: calculating foil strip scattered field data under different frequencies, observation angles and sizes by using a moment method; step three: fitting the amplitude of the foil strips in the scattering center model by adopting a polynomial function; step four: fitting the relation between parameters in the foil strip amplitude function and the calculated frequency by adopting a polynomial function; step five: and fitting the relation between the foil height and the foil radius and the foil scattering field to finally obtain a foil scattering center parameter model containing size information. The invention can simulate the foil scattered field echo under the condition of different foil sizes, can also adjust the foil types, the precision requirements and the like in time, adapts to the requirements of different calculations, can meet the requirements of rapidity of an anti-interference semi-physical simulation test, and can meet the requirements of accuracy of a digital simulation model.
Description
Technical Field
The invention relates to the technical field of electromagnetic scattering and application, in particular to a modeling method of a scattering center model of a foil strip.
Background
The radar countermeasure technology is more and more advanced, the foil strip is the most used and most important passive interference technology, and the foil strip is widely applied to scenes such as missile defense and self-defense of airplanes and ships by virtue of the outstanding characteristics of simple manufacture, low price, large interference range and the like. How to evaluate the effect of foil interference, how foil interference tactics should be used, etc. become the most important concern for the combat commander. In order to solve the above problems, a simple and effective method is to model and simulate the echo signal implementing the foil strip interference by a computer. Therefore, the establishment of the foil strip echo signal model has important reference value for researching the foil strip interference resisting technology.
The modeling methods of foil strip radar echoes are divided into two categories: one is a induction method, namely echo data meeting the characteristics are reversely obtained through random sequence simulation after the echo amplitude statistical characteristics and the power spectrum characteristics of the foil strip cloud cluster are directly obtained according to experimental data of the foil strip cloud cluster. At present, the common method is to divide the foil cloud cluster by adopting a layer-angle dividing method, calculate the foil unit bodies and then superpose the calculation results of the foil unit bodies.
The other type is a deduction method, namely echo data of a foil strip cloud are obtained in a forward direction according to the connection between the foil strip cloud and a foil strip on the basis of dynamic and electromagnetic modeling of a single foil strip. An important step in the algorithm is the analysis of the fringe field of the individual foil strips. A common foil strip is a thin wire that is at resonance in the incident electric field for half the incident wavelength, which produces the maximum RCS. The theoretical models for calculating the foil strip scattering field in the early stage are of two types: one class simply models dipoles and computes the spatial distribution and average of the scattered field, and this method is often used when the accuracy requirements are not high. The other type is that the foil strips are used as antenna oscillators, secondary radiation forms a scattered field under the action of incident wave feed, and the electric field distribution of the single foil strips is subjected to spatial averaging to obtain the average value of each foil strip. A typical calculation procedure is as follows:
in the geographic coordinate system, the position of the radar is (x)r,yr,zr)TThe position of the foil strip is (x)c,yc,zc)TThe radar advance distance is recorded as rrcThe sight line vector is denoted as dTIs a line of sight dTIncident electric field at the foil strip is EinThe horizontal polarization component and the vertical polarization component of the polarization are respectively expressed in a geographical coordinate system
And
the expression under the antenna coordinate system is respectively
And
the transition matrix from the geographic coordinate system to the antenna coordinate system is denoted as C, the angular relationship between the line of sight and the antenna is shown in fig. 8, and the angular relationship between the incident electric field and the foil strip is shown in fig. 9.
Can deduce the RCS of a single foil strip in VV polarization
Wherein, λ wavelength, θdIs the angle between the radar and the foil strip, f (theta)d) Backscatter directivity function for foil strips without taking into account polarization mismatch, cTIs the direction vector of the foil strip.
The prior art has the following disadvantages:
(1) although the existing induction model is simple in calculation, the problems of different radar polarization, different incidence directions, different foil attitude dip angle distributions and echo difference under different length proportioning conditions cannot be reflected.
(2) In the existing deduction model, a dipole or an antenna array is used for replacing a foil strip, factors influencing radar echo such as partial physical characteristics of the foil strip are ignored, and the description of a calculation model is not accurate enough.
(3) Meanwhile, matrix inversion is generally needed when the existing foil scattering model calculates a foil cloud scattering field, and because the actual number of foil clouds is huge, the matrix inversion greatly increases the calculation time, so that the efficiency is low;
therefore, aiming at the problems that the induction method can not solve and the problems that the existing deductive method model is large in calculation amount and low in precision, the invention provides a novel foil echo modeling method based on a scattering center, namely, the method is used for modeling and simulating the scattering center on the basis of foil scattering data calculated by a moment method at different angles and under different frequencies and sizes, and establishing a mathematical model of a foil radar echo. According to the model, the effect of foil strip interference in actual combat can be simulated more accurately and rapidly, and a simpler and more effective method is provided for better researching the performance of the foil strips.
Disclosure of Invention
The invention aims to provide a modeling method of a scattering center model of a foil strip, so as to solve the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme: a modeling method of a scattering center model of a foil strip comprises the following steps;
the method comprises the following steps: modeling the foil strips and dividing the foil strips by a triangular surface element;
step two: calculating foil strip scattered field data under different frequencies, observation angles and sizes by using a moment method;
step three: fitting the amplitude of the foil strips in the scattering center model by adopting a polynomial function;
step four: fitting the relation between parameters in the foil strip amplitude function and the calculated frequency by adopting a polynomial function;
step five: and fitting the relation between the foil height and the foil radius and the foil scattering field to finally obtain a foil scattering center parameter model containing size information.
Preferably, in step one, the foil strip is modeled using FEKO or CATIA and subdivided in triangular bins.
The modeling method of the scattering center model of the foil strip, provided by the invention, has the beneficial effects that:
1. the method is used for modeling on the basis of scattering data calculated by a foil actual model, and the model is not equivalent or simplified, so that the result is very accurate, and the simulation result shows that the RCS error of a single foil is only 0.12dB compared with the result obtained by calculating the model by using a moment method. From the ISAR image of the foil strip cloud cluster, the simulated foil strip cloud cluster is very close to the reality;
2. compared with the existing deductive modeling method, the method has the advantages that matrix inversion is not needed in the model calculation process, so that the calculation time of a foil strip cloud group scattering field formed by huge foil strips can be greatly reduced;
3. the invention can simulate the foil scattered field echo under the condition of different foil sizes, can also adjust the foil types, the precision requirements and the like in time, adapts to the requirements of different calculations, can meet the requirements of rapidity of an anti-interference semi-physical simulation test, and can meet the requirements of accuracy of a digital simulation model.
Drawings
FIG. 1 is a flow chart of a single foil strip modeling;
FIG. 2 is a schematic view of a single foil strip model;
FIG. 3 is a comparison of the RCS results for a single foil strip;
FIG. 4 is a graph of the random distribution range of foil strips;
FIG. 5 is a flow chart of foil cloud simulation;
FIG. 6 is a view of foil strip cloud RCS as a function of orientation;
FIG. 7 is a foil strip cloud ISAR image;
FIG. 8 is a view of the angle relationship between the line of sight and the antenna
FIG. 9 is a graph of the incident electric field versus the angle of the foil strips.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-9, the present invention provides a technical solution: a modeling method of a scattering center model of a foil strip comprises the following steps;
the method comprises the following steps: firstly, modeling a foil strip by using FEKO (FEKO-assisted engineering kok) or CATIA (computer-aided three-dimensional interactive application) and the like and subdividing by using a triangular surface element;
step two: and the scatterfield data is calculated using a moment method. The foil strip model is shown in a schematic diagram 4, which is an example of a miniature metal cylinder with a height h of 50mm and a bottom radius r of 10mm, because the foil strip is mostly used in electronic warfare;
step three: the scattering properties of the foil strips are described on the basis of an attribute scattering center model. According to the attribute scattering center model, a mathematical model of the scattering center of the foil strip under the fixed size is expressed by the following formula.
Where ξ ═ ξ (θ, φ) is the radar azimuth,
is the radar incidence direction, c0Is the speed of light, f is the calculated frequency,
is the foil strip direction and a (f, ξ) is the fringe field magnitude; calculating a scattering field of the foil strip at an angle of phi 0 DEG and theta 0 DEG-90 DEG under the frequency of 1.5G by using a moment method, and then fitting by a genetic algorithm to obtain the expression of the scattering field amplitude A (f, xi):
A(f,ξ)＝a(f)·φn(ξ)3+b(f)·φn(ξ)2+c(f)·φn(ξ)+d(f) (3)
wherein phi isn(xi) is the angle of the radar to the foil strip:
a (f), b (f), c (f), d (f) are frequency dependent functions;
step four: using a moment method to obtain the scattered field data of the single foil strip under the frequencies of 1GHz, 1.3GHz, 1.5GHz, 1.7GHz, 1.8GHz and 2GHz respectively, and obtaining the expressions of a (f), b (f), c (f), d (f) through fitting:
a(f)＝a1·f2+a2·f+a3 (5)
b(f)＝b1·f2+b2·f+b3 (6)
b(f)＝b1·f2+b2·f+b3 (7)
d(f)＝d1·f2+d2·f+d3 (8)
the undetermined parameters in the formulas (5) - (8) are obtained by estimation through an optimal matching algorithm, and the matched objective function is that the root mean square error between the RCS calculated by the model and the RCS calculated by a moment method is minimum; the final parameter values are shown in table 1;
TABLE 1 scattering center parameter Table
Step five: the size of the foil strip in practical application is not fixed and can be adjusted according to actual combat requirements, so that the influence of the size of the foil strip on the echo of the foil strip is further researched by continuously adopting a variable control method. Firstly, fixing the foil strip with constant height, and changing the radius of the foil strip to study the influence of the radius on an echo; then, the radius of the foil strip is fixed to be unchanged, the height of the foil strip is changed to study the influence of the height on the echo, and the specific size setting is shown in table 2;
TABLE 2 foil strip size
Finally, a foil strip echo model is obtained:
where h and r are the radius of the top and bottom surfaces of the cylindrical foil strip, h0＝50mm,r010mm, parameter a 1.05, b 1.29, height h in the range of [40mm,60mm]And a radius r of [6mm,18mm ]]When the error is within the range, the error of the calculation result is within 3dB compared with that of a moment method;
a pair of the scattering center modeling calculation result and the moment method calculation result such as fig. 5; wherein the size of the foil strips is h is 50mm, r is 10mm, the azimuth angle of the radar is phi 0 degrees, theta is 0 degrees to 90 degrees, the angle interval is 0.1 degrees, and the calculation frequency is f is 1.5 GHz; the root mean square error between the RCS calculated by the scattering center model and the RCS calculated by a moment method is only 0.12dB, which shows that the method can ensure the RCS precision of a single foil strip, and compared with other models, because matrix inversion is not needed in the method, the calculated amount can be greatly reduced and the calculation time of a foil strip cloud cluster scattering field can be shortened when a foil strip cloud cluster consisting of a huge number of foil strips is calculated;
based on the above specific embodiment, calculating the foil strip cloud radar echo:
according to the foil strip cloud echo signal for the production mechanism of single foil strip echo signal vector sum, can the scattered field of the foil strip cloud cluster of emulation distribution in certain space, establish that there are N foil strips in the foil strip cloud cluster, according to above-mentioned mathematical model, simulate the foil strip cloud echo and can obtain:
according to the formula (9), the distribution of the foil strip cloud cluster in the actual combat is simulated, and the distribution range is represented by p1(x1,y1,z1)， p2(x2,y2,z2) The expanded cube space is shown in fig. 6, and the positions and directions of the foil strips in the cube are randomly distributed;
the simulation process is as follows:
(1) initializing simulation parameters including radar azimuth, foil cloud range, number and the like;
(2) randomly generating the position and the direction of each foil strip;
(3) calculating the scattering field of the single foil strip;
(4) and the vector sum of all foil strip scattering fields is the scattering field of the foil strip cloud.
The simulation parameters are set as foil strip size h being 50mm, r being 10mm, radar azimuth phi being 0 DEG theta 0-90 DEG, angle number 451, frequency range 1 GHz-2 GHz, frequency point number 101, foil strip cloud range p1(-2,-2,-2)m,p2(2,2,2) m, and 500 foil strips;
when the frequency is f-1.5 GHz, the foil cloud RCS result obtained by simulation is shown in fig. 6, wherein the RCS mean value is-0.80 dBsm;
the ISAR image obtained by simulation is shown in FIG. 7, and the distribution of each foil strip and the scattering field intensity condition can be clearly seen from the ISAR image of the foil strip cloud cluster.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (2)
1. A modeling method of a scattering center model of a foil strip is characterized by comprising the following steps: comprises the following steps;
the method comprises the following steps: modeling the foil strips and dividing the foil strips by a triangular surface element;
step two: calculating foil strip scattered field data under different frequencies, observation angles and sizes by using a moment method;
step three: fitting the amplitude of the foil strips in the scattering center model by adopting a polynomial function;
step four: fitting the relation between parameters in the foil strip amplitude function and the calculated frequency by adopting a polynomial function;
step five: and fitting the relation between the foil height and the foil radius and the foil scattering field to finally obtain a foil scattering center parameter model containing size information.
2. The method of claim 1, wherein the method comprises: in the first step, the foil strip is modeled by using FEKO or CATIA and is divided by a triangular surface element.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114167810A (en) * | 2021-10-23 | 2022-03-11 | 西安电子科技大学 | Controllable foil strip cloud model manufacturing method and control system based on four-axis wire inserting machine |
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| CN114167810A (en) * | 2021-10-23 | 2022-03-11 | 西安电子科技大学 | Controllable foil strip cloud model manufacturing method and control system based on four-axis wire inserting machine |
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