CN110502782A

CN110502782A - The big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector

Info

Publication number: CN110502782A
Application number: CN201910607587.5A
Authority: CN
Inventors: 左炎春; 郭立新; 刘伟; 刘松华
Original assignee: Xian University of Electronic Science and Technology
Current assignee: Xian University of Electronic Science and Technology
Priority date: 2019-07-04
Filing date: 2019-07-04
Publication date: 2019-11-26
Anticipated expiration: 2039-07-04
Also published as: CN110502782B

Abstract

The invention belongs to electronics and scientific application technical field, disclose a kind of big scale of construction chaff cloud electromagnetic scattering measuring method based on outline vector transport theory；Distribution of the chaff cloud in wake flow is calculated in conjunction with Aerodynamics；Quick multidomain treat-ment is carried out to it using K-means algorithm based on chaff cloud spatial distribution model, and the electromagnetic propagation attenuation coefficient in each subregion is calculated using line moment method；Based on propagation attenuation coefficient in partition data and acquired region, establish vector transport equation in the entire area of space that chaff cloud occupies and solved using monte carlo method, using the transmitting of virtual photon, transport, collide, track, receive process acquire the Statistical Solutions of vector transport equation；Based on the solving result of vector transport equation, the acquisition of scattering HH, HV, VV, VH polarization mode is realized by Stokes vector conversion process.The present invention overcomes the not high problems of big scale of construction chaff cloud radar cross section computational efficiency in the prior art, meanwhile, efficiently solve chaff cloud radar cross section computational problem in aircraft wake.

Description

The big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector

Technical field

The invention belongs to electronics and scientific application technical field more particularly to a kind of big scale of construction transported based on outline vector Chaff cloud electromagnetic scattering measuring method.

Background technique

Currently, the immediate prior art: in present electromagnetic warfare, the usage history of chaff cloud is long, production is simple, effect Obviously, low in cost, oneself is through being widely used in battlefield.It has suffered as electronic countermeasure between ourselves and the enemy as main Reconnaissance Equipment Radar plays vital effect in the defence of countries in the world.Thus modern war is especially in future war, chaff Perturbation technique by discharging big scale of construction chaff in space, cause enemy radar acquisition echo and the true echo of target it Between differ greatly, so that enemy radar cannot accurately and quickly identify target, this conflicting mode does not need to understand enemy in advance The characteristic that Fanglei reaches, versatility is stronger, and to the interference of radar, there are mainly two types of modes, first is that by chaff interferent generation echo, The true echo of target is covered, second is that setting chaff interferent spatial position and structure, make his echo and true target echo phase Seemingly, come inveigle enemy radar to target detect Check judgement.

Currently, mainly using Hardware In The Loop Simulation Method, numerical algorithm, independence to dissipate the calculating of chaff cloud radar cross section The statistical stacking method of shooting method, scattering section based on single chaff.Hardware In The Loop Simulation Method uses the conduct of part real data A part of emulation can obtain the analog result of more closing to reality situation, be a kind of reliable emulation technology, from mentioning Start out, be just widely used in system development and simulated experiment, numerical algorithm (moment method etc.) is to solve for Maxwell equation The integral or differential form of group realize the calculating of Chaff Clouds radar cross section；Independent scattering method is based on single chaff Total space scattering properties realizes that Chaff Clouds radar cross section calculates by rotation transformation and incoherent statistical stacking, certainly, Also having many researchs is to realize that Chaff Clouds radar scattering is cut by many experiments based on measured result expansion further analysis It estimates and characteristic research in face.

In conclusion Chaff Clouds radar scattering calculates (estimating) technology, there are several significant deficiencies: firstly, based on number Although the chaff cloud radar cross section of value-based algorithm calculates accurately, it needs to solve extensive matrix equation, when unknown number number Amount reaches 10¹⁴When the order of magnitude, even supercomputer is also required to the comparable time to solve this equation, if computing resource is (as in Deposit, calculate the time) it is limited, then it will be unable to carry out big scale of construction chaff cloud electromagnetism Scattering Calculation, meanwhile, use numerical method meter Calculate chaff cloud be only capable of lower one group of counting statistics meaning it is possible as a result, to obtain Statistical Solutions, then need repeatedly multisample to calculate, This will expend a large amount of manpower and material resources.Secondly, the Chaff Clouds radar cross section based on measured result, which calculates, to be had centainly Realistic meaning, but can not exhaustive other possible situations in addition to experiment, measured result is difficult to be promoted, especially aircraft wake The diffusion of middle chaff cloud and scattering data are rare, cause not implementing using supposition algorithm of the available data to unknown result, then It is secondary, although speed is estimated quickly based on the Chaff Clouds radar cross section calculating independently scattered, due to existing between chaff Electromagnetic coupling, and independent scattering method ignores the multiple coupling between chaff, the confidence level for being allowed to calculated result is lower, finally, Chaff Clouds radar cross section in terms of Geometric Modeling, due to the sensibility and tip property to study a question, in aircraft wake It calculates rarely seen in open source literature.

In conclusion problem of the existing technology is:

(1) limitation and needs of the chaff cloud radar cross section calculating based on numerical algorithm due to computing resource solve Unknown number enormous amount leads to not the radar cross section for calculating extensive chaff cloud.

(2) the Chaff Clouds radar cross section based on measured result calculates measured result and is difficult to be promoted；Due to foil There are electromagnetic coupling between item, independent scattering method ignores the multiple coupling between chaff, keeps the confidence level of calculated result lower.

(3) the Chaff Clouds radar cross section in aircraft wake calculates rarely seen in open source literature.

Solve above-mentioned technical problem difficulty: in order to solve the above-mentioned technical problem, mainly there is following technological difficulties: how Realize that quick multipolarization calculating is a main problem in the case where coupling between consideration chaff.

It solves the meaning of above-mentioned technical problem: realizing the quick calculating of Chaff Clouds radar cross section in aircraft wake, The use and jamming effectiveness promotion of chaff cloud can be effectively facilitated, while providing one kind fastly for the small scatterer electromagnetism calculating of extensive electricity The efficient calculation method of speed.

Summary of the invention

In view of the problems of the existing technology, the present invention provides a kind of big scale of construction chaff clouds transported based on outline vector Electromagnetic scattering measuring method.

The invention is realized in this way a kind of big scale of construction chaff cloud electromagnetic scattering measurement side transported based on outline vector Method, the big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector the following steps are included:

The first step calculates distribution of the chaff cloud in wake flow in conjunction with Aerodynamics；

Second step carries out multidomain treat-ment using K-means algorithm based on chaff cloud spatial distribution model, and uses line square amount Attenuation coefficient information in region needed for method calculates vector radiative transfer theory；

Third step, the region self-energy attenuation coefficient based on partition data and acquisition, using monte carlo method to vector Transport equation is solved, and is emitted using photon, is transported, collided, the method for receive process tracking realizes that vector transports integral side The parallel rapid solving of Cheng Fangcheng；

4th step, based on the solving result of vector transport equation, by Stokes vector or its transformation realize HH, HV, The solution of VV, VH polarization mode.

Further, the big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector is put into slice type Three-dimensional chaff cloud diffusion model construction method includes:

(1) foundation of fluid mechanics equation, the movement diffusion equation based on the available chaff center position of N-S equation It is as follows:

Wherein, v_xAnd v_yIt is along the direction x and y speed, D is invasin, and s (r, t) is chaff cloud number density；

For the above-mentioned equation of solution, upstreame scheme difference form is used:

It can upper Density Distribution in the hope of chaff in each moment, each section using finite time-domain differential technique；

(2) the speed field direction relied on its position is directed toward in the space of chaff, if the speed of certain root chaff position Degree field can be expressed asThen define two three vectors:

And enable, θ be chaff orientation vector withThe angle of vector,It is chaff orientation vector in vectorThat opens is flat Projection vector and vector on faceThe angle of positive direction, and have θ,Probability density function are as follows:

According to chaff central point generation strategy and chaff is generated by probability density at random to be orientated, and can establish aircraft wake Under the influence of chaff cloud spatial distribution model.

Further, the big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector carries out Chaff Clouds Spatial distribution data is read, and is carried out Chaff Clouds region division based on K-means algorithm and comprised the steps of:

(1) spatial distribution and orientation information of chaff cloud, the reading format of data are read are as follows:

Wherein, (x, y, z) is the coordinate of chaff central point, and unit is rice,It is the orientation of chaff, unit is radian；

(2) in K-means algorithm K value determine cluster result in classification quantity, to chaff cloud classify foundation be The distance between chaff, the therebetween reversed distribution number density for reflecting chaff cloud different zones；Chaff cloud subregion includes:

1. randomly choosing K central point in the point model of chaff center；

2. traversing all chaff cloud space center point data, each chaff central point is attributed to K and drafts central point institute In corresponding classification；

3. calculating the center of gravity of each subclass in K cluster, and the central point as K new classification；

4. step is repeated 2., 3., until K class central point no longer changes or be less than specified threshold；Chaff cloud is subjected to subregion.

Further, described to be made based on the big scale of construction chaff cloud electromagnetic scattering measuring method that outline vector transports in each subregion With random sampling algorithm, adjacent a small amount of chaff is extracted using line moment method MoM and calculates the polarization that electromagnetic wave is propagated in the area Transmission loss, and database is established, comprising the following steps:

(1) chaff needed for determining the subsequent calculating using MoM using discrete event sampling algorithm in each subregion, specifically It comprises the steps of:

1. choosing a certain chaff in the region using uniform random number seed in certain subregion:

N (i)=unrand (1, M_i)；

Wherein, function unrand (1, M_i) can be randomly generated according to being uniformly distributed more than or equal to 1 and less than or equal to M_iIt is just whole Number N (i), label i are the call number in region, M_iIndicate ith zone chaff total quantity；

2. finding the Q root chaff closed on the most with N (i) numbers chaff using K-means algorithm in certain subregion；

3. calculating the Q root foil electromagnetic scattering selected using line moment method is divided into T sections as a result, setting every chaff, every One section of upper definition Basis Function:

Wherein, x_mFor m sections of midpoint, Δ x_mFor m sections of length.Then all chaff electric currents can indicate are as follows:

Wherein, α_nIt is undetermined coefficient,Be defined on n-th section, be zero in other sections, when chaff be perfact conductor or When PEC, following improved Electric Field Integral Equation can be established on chaff surface:

Wherein,WithRespectively site and source point,For incidence wave electric field strength, examined using Galerkin method It tests, obtains:

Wherein, L is integral equation linear operator, establishes matrix equation:

[l_mn][α_n]=[g_m]；

Wherein:

Above-mentioned matrix equation is solved, the current distribution on Q root chaff surface is obtained:

Far-field scattering is acquired, and determines the far field radar cross section of Q root chaff:

4. according to following formula computed losses coefficient κ on the basis of obtaining the radar cross section of Q root chaff:

κ=- n σ；

Wherein, n is the number density of unit volume chaff, for different subregions, is calculated i.e. using identical method It can；

For not same polarization, loss factor when calculating only needs that in-field is taken to compare with the not co polarized component of scattered field:

Wherein,Indicate the vertically and horizontally component of scattered field,Indicate in-field Vertically and horizontally component.

Further, the big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector is based on Delaunay Algorithm carries out triangulation to above-mentioned each subregion and external envelope is established, and each triangle top of external envelope for establishing different zones Point, normal vector, central point index list, establish database, comprising the following steps:

(1) two dimension Delaunay algorithm only exists unique triangulation methodology for any given point set, and follows Minimum angle maximum and empty circumscribed circle " criterion, basic step are as follows:

1. selecting a chaff central distribution point P₁As the first vertex of triangle, distance P is selected₁Nearest chaff distributed point As the second vertex of triangle, it is denoted as P₂；

2. selecting the third vertex P of triangle₃, make itself and P₁、P₂Without other tops in the circumscribed circle of the triangle of composition Point, also, vertex P in the triangle₃The interior angle opened is maximum；

3. generating three sides, side list is added, and generate first triangle, sets up triangle table；

4. select one from list, the corresponding flag bit in side will be changed and be set as 0；It is searched for from remaining spatial point list One satisfaction: first, this is in the opposite side of side institute third point in the triangles, and second, the triangle of the point and side composition Circumscribed circle in there is no other points, meet the point of the above-mentioned condition subtended angle in new triangle it is maximum that as P₃；

5. if be added into side table tail when there is no newborn in 4. in list, and set the flag bit on newly-generated side as 0；If had existed, the flag bit that these sides are arranged is 1, and triangle table is added in the triangle of generation, will be from 4. middle choosing That side flag bit selected is set as 1；The process is gone to 1., until the flag bit on all sides is 1；

(2) three-dimensional Delaunay algorithm realizes step substantially:

Triangulation network growth algorithm first finds out the two o'clock that distance is nearest in chaff cloud spatial distribution, and forms line, then presses The criterion of Delaunay triangulation network finds out another endpoint of the Delaunay triangle comprising this side, successively handles all new The side of generation, until all the points are disposed, the basic step of triangulation network growth algorithm is as follows:

It is taken a bit 1. appointing in chaff spatial distribution point, and finds and put nearest point apart from this, connection two o'clock constitutes initial Baseline finds third point using triangulation criterion, forms initial Delaunay triangle；

2. extended triangular grid.Using 3 sides of initial delta as initial baseline, finds and be somebody's turn to do using external empty ball criterion 3 initial baselines form 3 points of Delaunay triangulation network；

3. step is repeated 2., until concentrating all points are processed to finish；

(3) after carrying out above-mentioned subdivision, in order to find external envelope point, using following algorithm steps:

1. finding the maximum value and minimum value of three dimensions according to given chaff cloud spatial data:

x_max, x_min, y_max, y_min, z_max, z_min；

And subdivision is carried out using cuboid in space, the side length on three directions of each square is (Δ x, Δ y, Δ Z), then, the central point of each cubical area are as follows:

And

Wherein, ceil () function representation rounds up number；

2. since external envelope point is only possible to that contraction algorithm can be used there are in the grid on the outside of cuboid, outside Each layer of box is inwardly searched for, is stopped in the presence of encountering box a little；

(4) external envelope triangulation exterior normal direction is determined, using continuously normal orientation calculation criterion outside side is faced, if two-phase Adjacent vertex of a triangle is respectively A, B, C and B, C, D.And m is set, n, p are the 1st Atria vertex serial numbers, and w, g, h is the 2nd Three vertex of triangle, sequence according to right-hand screw rule and from small to large calculate the 1st triangulation method vector are as follows:

If the label on three vertex of the 2nd triangle arrives from childhood is followed successively by one of BDC, CBD, DCB greatly, so continue Go down, number all triangular apex, then each triangle is in circulation, as long as can determine outer method according to the right-hand rule Line direction, the algebraic average that three apex coordinates can be used for external envelope center point coordinate calculate.

Further, described that model vector is established based on the big scale of construction chaff cloud electromagnetic scattering measuring method that outline vector transports Transport equation, and the equation is solved using monte carlo method comprising the steps of:

(1) consider that the source plane of antenna radiation pattern generates, which is the premise and basis of subsequent vector transport theory, packet Containing following steps:

1. reading in the far-field pattern information of antenna according to the antenna that outside is given；

2. at given electromagnetic wave incident angleIn the case of, establish the equation of source plane:

Wherein, the central point of source plane is selected as:

External envelope point is projected on plane Π, and reuses Delaunay algorithm and provides plane external envelope；

3. using Fibonacci grid, and its sampled point in the external envelope generating source plane generated, pressed in the plane of source Coordinate system is defined according to following mode:

And it is its is unitization:

The position vector for remembering each vertex of external envelope is (x_i,outline,y_i,outline,z_i,outline), by it in above-mentioned definition Vector on project, findWithThe circle that may include all external envelope points is found in dimension plane, remembers that its radius is R_min, Then it can produce grid using Fibonacci grid policies are as follows:

It needs to determine simultaneously, if the point (v generated_n,w_n) not in maximum external envelope, then it is rejected；

4. according to directivity function and the discrete event methods of sampling, just source emits point sampling, and being located in specified external envelope makes It is P (i) with the thermogenetic discrete point of Fibonacci net, the normalized radiation pattern value that each pair of point is answered is Q (i), then can be according to Following mode generating source sampling；

Calculate cumulative probability:

A random number is generated according to being uniformly distributed:

Randnumber=rand ()；

Wherein, function can produce the random number in [0,1] section；If M (m)≤randnumber≤M (m+1), is taken out The source point serial number m taken, corresponding coordinate is P (m)；

(2) source transmitting photon intersects judgement with the outer triangulation face of chaff cloud.Above-mentioned steps have extracted source point:

P (m)=(x_sm,y_sm,z_sm)；

And the direction of propagation of known incident wave are as follows:

Then write out the linear equation of Particles Moving are as follows:

X=x_sm+t·n_x, y=y_sm+t·n_y, z=z_sm+t·n_z；

Wherein, t is parameter；

Certain external envelope triangle sentences friendship method with straight line, if three vertex for needing to sentence the triangle of friendship can be denoted as TR₁, TR₂, TR₃, then the point of triangle interior indicates are as follows:

The straight line expression formula derived is substituted into obtain:

λ₁(TR₁-TR₂)+λ₂(TR₁-TR₃)+t n_x n_y n_z=TR₁-P m)；

It writes a Chinese character in simplified form are as follows:

λ₁a+λ₂B+tc=d；

Write as matrix form are as follows:

Solution are as follows:

If λ₁,λ₂∈ [0,1], then ray and chaff cloud external envelope have intersection point, when there is multiple intersection points, need using most Small t rule judges the first intersection point；

(3) photon is transmitted in chaff cloud according to probability, is solved vector transport equation using monte carlo method and is realized, if N root chaff is randomly dispersed in a length of ds, and volume is in the cylindricality body unit of dv, and the electromagnetic wave that a radiation intensity is I passes through the list Member, by the variable quantity of the available electromagnetic wave radiant intensity of law of conservation of energy are as follows:

Wherein,It is incident intensityAnd scattering strengthBetween transfer coefficient or matrix, above formula First item refer to due to chaff absorb κ_as, scattering κ_s, background absorption κ_abCaused energy dissipation, what Section 2 indicated is empty Between other radiation source radiations energy, Section 3 indicate be that multiple scattering body coupling scattering existsScattering strength summation on direction, Wherein:

If in space, the duty ratio of chaff is f_s, then the absorption coefficient of background indicates are as follows:

κ_ab=2k " (1-f_s), k " is wave numberImaginary part；

Chaff absorptivity is the ratio of chaff loss field energy and incident field energy, service wear fieldIt indicates are as follows:

Here four Stokes vectors sanctified by usage are introduced:

Vector transport equation is solved based on monte carlo method to comprise the steps of:

1. free path is sampled.The step of passing through front, available photon enter the specific location of chaff cloud for the first time, and It is sampled according to following free path formula, obtains the walked distance of next impinging photon:

Wherein, ξ is the uniform random number between [0,1], K_eIt is extinction coefficient；

2. chaff orientation sampling.The orientation of chaff is by Space AngleIt determines, if the probability density function that they are obeyed is P (θ) andScattering direction is extracted using rejection technique；

Firstly, in θ ∈ [0, π],Between according to be uniformly distributed extract the chaff angle of orientationI.e. just like Lower formula:

ξ is the uniform random number between [0,1]；

Bring the chaff angle of orientation into probability density function

Secondly, InA uniform random number P is generated again using above-mentioned ξ on section₀, Angle of departure selection is carried out according to following judgment criterion:

If what above-mentioned criterion provided is refusalSelection, which then needs to return to the first step, to be continued, full until generating Until several pairs required enough；

3. scattering direction sampling；It is scattered direction sampling based on the conservation of energy and rejection technique, is located at entering for a certain determination Firing angleUnder, the energy of scattering is written as:

And:

The then probability density that particle is emitted along direction are as follows:

Wherein, it indicatesDirection scattering coefficient, is defined:

It is consistent with selection incident direction method, it is carried out using rejection technique, basic step are as follows:

Firstly, in θ ∈ [0, π],Between according to being uniformly distributed the extraction angle of departureI.e. just like following formula Son:

ξ is the uniform random number between [0,1]；

Bring the launch angle of calculating into probability density functionHave:

Secondly, InA uniform random number P is generated again using above-mentioned ξ on section₀, press Angle of departure selection is carried out according to following judgment criterion:

If what above-mentioned criterion provided is " refusalSelection ", which then needs to return to the first step, to be continued, until generating Until several pairs met the requirements；

4. scattering transmission energy harvesting, calculates the decay factor collided every time, under the conditions of given incidence wave, all dissipate Field energy is penetrated to be written as:

Energy W in this way before single collisions_i-1With the energy W after collision_iBetween relationship are as follows:

Repeat it is above-mentioned 1.~4. until photon projects chaff cloud, accumulate enough photons and just carry out at subsequent data Reason, judges whether the primitive decision method inside and outside cloud is photon, from the point to launched in arbitrary direction ray, judge ray with it is several The intersection point number of what body, odd number be it is interior, even number is then put in outside；

(4) photon outgoing and collection of energy, continuously according to process generate photon, photon and scatterer collide and track The track of photon will scatter energy to it after photon leaves scatterer and count；

The photon for being 1 equipped with N number of energy is launched, and has M photon to escape from cloud cluster through continuous collision, and scattering direction is respectivelySelf-contained energy is respectively I_i, to the total spaceTo grid dividing is carried out, the step-length at the angle θ is Δ θ,Angle Step-length beSimultaneously have θ=m Δ θ,Judgement outgoing photonWhether the method for (m, n) unit is entered It is:

Then, InTotal photon energy that direction receives are as follows:

Complex operation is carried out to data are solved, obtains required polarization data comprising the steps of: according to following side Formula calculates radar cross section, InThe radar cross section in direction indicates are as follows:

Another object of the present invention is to provide the big scale of construction chaff cloud electricity transported described in a kind of application based on outline vector The radar of magnetic scattering measuring method.

In conclusion advantages of the present invention and good effect are as follows: the present invention is using hydrodynamics diffusion equation to chaff cloud The Density Distribution of group is calculated, and the movement of single chaff is substituted with the movement of medium, is substantially reduced artificial resource consumption, is mentioned High model foundation efficiency.

1 progress contrast table of table

Serial number	Comparison project	Researcher	The present invention	Remarks
					1	Chaff quantity	10⁶	10⁹	Lv Mengmeng etc.
2	Chaff cloud form	It is spherical	Arbitrary shape	Li Jinliang etc.
					3	The diffusion of chaff wake flow	It has not been reported	It may be implemented	—

The present invention is based on Delaunay algorithm to Chaff Clouds carry out multidomain treat-ment, the treatment effeciency of the model of promotion, and Ray is sentenced to the adaptability and efficiency that scattering algorithm within algorithm, is improved within friendship method.

The present invention solves vector transport equation using monte carlo method, and the simple strong operability of principle is convenient for Full dual station can be achieved in follow-up data processing in specified emulation number, polarization radar scattering section obtains.

Detailed description of the invention

Fig. 1 is the big scale of construction chaff cloud electromagnetic scattering measuring method provided in an embodiment of the present invention transported based on outline vector Flow chart.

Fig. 2 is the big scale of construction chaff cloud electromagnetic scattering measuring method provided in an embodiment of the present invention transported based on outline vector Implementation flow chart.

Fig. 3 is active characteristics database construction module sub-process figure provided in an embodiment of the present invention.

Fig. 4 is indoor environment extracting change information module sub-process figure provided in an embodiment of the present invention.

Fig. 5 is movement monitoring module sub-process figure provided in an embodiment of the present invention.

Fig. 6 is active characteristics extraction module sub-process figure provided in an embodiment of the present invention.

Fig. 7 is activity recognition module sub-process figure provided in an embodiment of the present invention.

Fig. 8 is provided in an embodiment of the present invention and now there are two types of indoor occupant activity recognition method simulation result comparison diagrams.

Fig. 9 is provided in an embodiment of the present invention when experimental situation is constant, to whether the personnel based on principal component analysis are living Dynamic identification carries out simulation comparison figure.

Figure 10 is loudspeaker provided in an embodiment of the present invention and chaff cloud relational graph.

Figure 11 is electromagnetic horn filed-close plane Energy distribution schematic diagram provided in an embodiment of the present invention.

Figure 12 is chaff cloud total space RCS distribution map provided in an embodiment of the present invention.

Figure 13 is section H polarization schematic diagram provided in an embodiment of the present invention.

Figure 14 is section V polarization schematic diagram provided in an embodiment of the present invention.

Figure 15 is electromagnetic horn filed-close plane Energy distribution schematic diagram provided in an embodiment of the present invention.

Figure 16 is chaff cloud total space RCS distribution map provided in an embodiment of the present invention.

Figure 17 is section H polarization schematic diagram provided in an embodiment of the present invention.

Figure 18 is section V polarization schematic diagram provided in an embodiment of the present invention.

Figure 19 is electromagnetic horn filed-close plane Energy distribution schematic diagram provided in an embodiment of the present invention.

Figure 20 is chaff cloud total space RCS distribution map provided in an embodiment of the present invention.

Figure 21 is section H polarization schematic diagram provided in an embodiment of the present invention.

Figure 22 is section V polarization schematic diagram provided in an embodiment of the present invention.

Figure 23 is electromagnetic horn filed-close plane Energy distribution schematic diagram provided in an embodiment of the present invention.

Figure 24 is chaff cloud total space RCS distribution map provided in an embodiment of the present invention.

Figure 25 is section H polarization schematic diagram provided in an embodiment of the present invention.

Figure 26 is section V polarization schematic diagram provided in an embodiment of the present invention.

Specific embodiment

In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to embodiments, to the present invention It is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to Limit the present invention.

In view of the problems of the existing technology, the present invention provides a kind of big scale of construction chaff clouds transported based on outline vector Electromagnetic scattering measuring method, is with reference to the accompanying drawing explained in detail the present invention.

As shown in Figure 1, the big scale of construction chaff cloud electromagnetic scattering provided in an embodiment of the present invention transported based on outline vector is surveyed Determine method the following steps are included:

S101: distribution of the chaff cloud in wake flow is calculated in conjunction with Aerodynamics；

S102: multidomain treat-ment is carried out to it using K-means algorithm based on chaff cloud spatial distribution model, and uses line square Attenuation coefficient information in region needed for amount method calculates vector radiative transfer theory；

S103: the region self-energy attenuation coefficient based on partition data and acquisition, it is defeated to vector using monte carlo method Fortune equation is solved, and is emitted using photon, is transported, collided, the method for receive process tracking realizes that vector transports integral equation The rapid solving of equation；

S104: the solving result based on vector transport equation, by Stokes vector or its transformation realize HH, HV, VV, The solution of VH polarization mode.

Technical scheme of the present invention will be further described with reference to the accompanying drawing.

The present invention is to solve the problems, such as big scale of construction complete polarization Chaff Clouds electromagnetic scattering (radar cross section)；Use fluid force It learns diffusion equation derived from equation to reappear the distribution of Chaff Clouds geometry, be calculated followed by Delaunay algorithm, K-means Method classifies to cloud cluster according to specified classification standard, later based on vector radiative transfer theory and monte carlo method to chaff cloud Single, double station electromagnetic scattering (radar cross section) is calculated, and is eventually passed through complex operation and is obtained each polarization scattering characteristics (radar Scattering section).

Application principle of the invention is explained in detail with reference to the accompanying drawing.Basic principle block diagram such as Fig. 2 institute of algorithm Show.

(1) it pre-processes, such as Fig. 3, the foundation of Chaff Clouds diffusion model in aircraft wake.Since big scale of construction Chaff Clouds can To be considered as random medium, it is contemplated that Aircraft Training Vortices speed can establish one only along the tangential direction in dispensing direction Slice type three-dimensional chaff cloud diffusion model.

(1.1) foundation of fluid mechanics equation, the movement diffused sheet based on the available chaff center position of N-S equation Journey is as follows:

Wherein, v_xAnd v_yIt is along the direction x and y speed, D is invasin, and s (r, t) is chaff cloud number density.

For the above-mentioned equation of solution, upstreame scheme difference form can be used:

It can upper Density Distribution in the hope of chaff in each moment, each section using finite time-domain differential technique.

(1.2) the speed field direction relied on its position is directed toward in the space of chaff, if certain root chaff position Velocity field can be expressed asThen define two three vectors:

(2) such as Fig. 4, the reading of Chaff Clouds spatial distribution data is carried out, and Chaff Clouds area is carried out based on K-means algorithm Domain divides and comprises the steps of:

(2.1) spatial distribution and orientation information of chaff cloud are read, the reading format of data is (as shown in table 2):

Wherein, (x, y, z) is the coordinate of chaff central point, and unit is rice,It is the orientation of chaff, unit is radian.

2 chaff cloud data memory format table of table

(2.2) in K-means algorithm K value determine cluster result in classification quantity, generally according to engineering actual selection.It is right The foundation that chaff cloud is classified is the distance between chaff, therebetween the reversed distribution number density for reflecting chaff cloud different zones, foil Cloud subregion includes following several steps:

1. randomly choosing K central point in chaff center point model (data)；

4. step is repeated 2., 3., until K class central point no longer changes (or being less than specified threshold)；It in this way can be according to wanting It asks and chaff cloud is subjected to subregion.Data memory format is as shown in table 3 after subregion.

3 chaff cloud data partition flag storage format table of table

Serial number	x	y	z	Area code
					1
2
					……	……	……	……

(3) such as Fig. 5, random sampling algorithm is used in each subregion, adjacent a small amount of chaff is extracted and utilizes line moment method (MoM) The polar transmission loss (attenuation coefficient) that electromagnetic wave is propagated in the area is calculated, and establishes database comprising the steps of:

(3.1) chaff needed for determining the subsequent calculating using MoM using discrete event sampling algorithm in each subregion, Comprising the following steps:

1. choosing a certain chaff in the region using uniform random number seed in certain subregion, it may be assumed that

N (i)=unrand (1, M_i)；

Wherein, α_nIt is undetermined coefficient,Be defined on n-th section, be zero in other sections, when chaff be perfact conductor (or When PEC), following improved Electric Field Integral Equation can be established on chaff surface:

Wherein,WithRespectively site and source point,For incidence wave electric field strength, examined using Galerkin method It tests, available:

Wherein, L is integral equation linear operator, can establish matrix equation on this basis:

[l_mn][α_n]=[g_m]；

Wherein:

Above-mentioned matrix equation is solved, the current distribution on available Q root chaff surface uses on this basis:

κ=- n σ；

Wherein, n is the number density of unit volume chaff, for different subregions, is calculated i.e. using identical method It can.

For not same polarization, loss factor when calculating only needs that in-field is taken to compare with the not co polarized component of scattered field, That is:

(4) such as Fig. 6, triangulation is carried out to above-mentioned each subregion based on Delaunay algorithm and external envelope is established, and built The each triangular apex of external envelope, normal vector, the central point index list of vertical different zones, establish database, it is specific comprising with Lower step:

(4.1) two dimension (net increases) Delaunay algorithm only exists unique triangulation side for any given point set Method, and follow " minimum angle is maximum " and " empty circumscribed circle " criterion, basic step are as follows:

5. if be added into side table tail when there is no newborn in 4. in list, and set the flag bit on newly-generated side as 0；If had existed, the flag bit that these sides are arranged is 1, and triangle table is added in the triangle of generation, will be from 4. middle choosing That side flag bit selected is set as 1；The process is gone to 1., until the flag bit on all sides is 1.

(4.2) three-dimensional (net increases) Delaunay algorithm realizes step substantially:

Triangulation network growth algorithm first finds out the two o'clock that distance is nearest in chaff cloud spatial distribution, and forms line (i.e. The side Delaunay), the another of the Delaunay triangle comprising this side is then found out by the criterion of Delaunay triangulation network Endpoint successively handles all newly-generated sides, and until all the points are disposed, the basic step of triangulation network growth algorithm is as follows:

It is taken a bit 1. appointing in chaff spatial distribution point, and finds and put nearest point apart from this, connection two o'clock constitutes initial Baseline finds third point using triangulation criterion, forms initial Delaunay triangle.

2. extended triangular grid.Using 3 sides of initial delta as initial baseline, finds and be somebody's turn to do using external empty ball criterion 3 initial baselines form 3 points of Delaunay triangulation network.

3. step is repeated 2., until concentrating all points are processed to finish.

(4.3) after carrying out above-mentioned subdivision, in order to find external envelope point (external envelope triangle), following algorithm can be used Step:

x_max, x_min, y_max, y_min, z_max, z_min；

And

Wherein, ceil () function representation rounds up number.

2. since external envelope point is only possible to that contraction algorithm can be used there are in the grid on the outside of cuboid, outside Each layer of box is inwardly searched for, is stopped in the presence of encountering box a little.For the judgement of outermost layer cuboid box, have:

4 external envelope point of table determines

(4.4) external envelope triangulation exterior normal direction is determined.Using continuously facing normal orientation calculation criterion outside side, if two The vertex of adjacent triangle is respectively A, B, C and B, C, D.And m is set, n, p are the 1st Atria vertex serial number, w, g, h Three vertex of 2 triangles, sequence according to right-hand screw rule and from small to large calculate the 1st triangulation method vector are as follows:

(5) such as Fig. 7, model vector transport equation is established, and solve to the equation using monte carlo method, includes Following steps:

(5.1) consider that the source plane of antenna radiation pattern generates, which is the premise and basis of subsequent vector transport theory, Mainly comprise the steps of:

1. read in the far-field pattern information of antenna according to the antenna that outside is given, and according to format shown in table 5 store with It is standby to use, wherein θ,It is Antenna Far Field deflection, E_thetaAnd E_phiIt is far field designated position electric fieldWithComponent.

5 antenna radiation pattern information data storing format table of table

2. at given electromagnetic wave incident angleIn the case of, it can establish the equation of source plane:

Wherein, the central point of source plane can be selected as:

Above-mentioned step has obtained the external envelope and its subdivision of given Chaff Clouds, and external envelope point is enterprising in plane Π Row projection, and reuse Delaunay algorithm and provide plane external envelope.

3. the sampled point in the external envelope generating source plane generated using Fibonacci grid and its previous step, flat in source Coordinate system is defined on face in the following way:

And it is its is unitization:

It needs to determine simultaneously, if the point (v generated_n,w_n) not in maximum external envelope, then it is rejected.

4. according to directivity function and the discrete event methods of sampling, just source emits point sampling, and being located in specified external envelope makes It is P (i) with the thermogenetic discrete point of Fibonacci net, the normalized radiation pattern value that each pair of point is answered is Q (i), then can be according to Following mode generating source sampling.

Calculate cumulative probability:

A random number is generated according to being uniformly distributed:

Randnumber=rand ()；

Wherein, function can produce the random number in [0,1] section.If M (m)≤randnumber≤M (m+1), is taken out The source point serial number m taken, corresponding coordinate is P (m).

(5.2) source transmitting photon intersects judgement with the outer triangulation face of chaff cloud.Above-mentioned steps have extracted source point:

P (m)=(x_sm,y_sm,z_sm)；

And the direction of propagation of known incident wave are as follows:

The linear equation of Particles Moving can then be write out are as follows:

X=x_sm+t·n_x, y=y_sm+t·n_y, z=z_sm+t·n_z；

Wherein, t is parameter.

Certain external envelope triangle sentences friendship method with straight line, if three vertex for needing to sentence the triangle of friendship can be denoted as TR₁, TR₂, TR₃, then the point of triangle interior can indicate are as follows:

The straight line expression formula derived is substituted into available:

λ₁(TR₁-TR₂)+λ₂(TR₁-TR₃)+t n_x n_y n_z=TR₁-P m)；

It might as well write a Chinese character in simplified form are as follows:

λ₁a+λ₂B+tc=d；

Write as matrix form are as follows:

It is solved are as follows:

If λ₁,λ₂∈ [0,1], then ray and chaff cloud external envelope have intersection point, when there is multiple intersection points, need using most Small t rule judges the first intersection point.

(5.3) photon is transmitted in chaff cloud according to probability, is solved vector transport equation using monte carlo method and is realized, If n root chaff is randomly dispersed in a length of ds, volume is in the cylindricality body unit of dv, and the electromagnetic wave that a radiation intensity is I is by being somebody's turn to do Unit, by the variable quantity of the available electromagnetic wave radiant intensity of law of conservation of energy are as follows:

If in space, the duty ratio of chaff is f_s, then the absorption coefficient of background can indicate are as follows:

κ_ab=2k " (1-f_s), k " is wave numberImaginary part；

Here four Stokes vectors sanctified by usage are introduced:

ξ is the uniform random number between [0,1]；

Bring the chaff angle of orientation into probability density function

If what above-mentioned criterion provided is " refusalSelection ", which then needs to return to the first step, to be continued, full until generating Until several pairs required enough.

3. scattering direction sampling.It is scattered direction sampling based on the conservation of energy and rejection technique, is located at entering for a certain determination Firing angleUnder, the energy of scattering can be written as:

And:

Wherein, it indicatesDirection scattering coefficient, is defined:

Above selection incident direction method is consistent, is carried out using rejection technique, basic step are as follows:

ξ is the uniform random number between [0,1]；

Bring the launch angle of calculating into probability density functionHave:

If what above-mentioned criterion provided is " refusalSelection ", which then needs to return to the first step, to be continued, until generating Until several pairs met the requirements.

4. scattering transmission energy harvesting.The decay factor collided every time is calculated, under the conditions of given incidence wave, all Scattering field energy can be written as:

Repeat it is above-mentioned 1.~4. until photon projects chaff cloud, subsequent data can be carried out by accumulating enough photons Processing, judges whether the primitive decision method inside and outside cloud is photon, from the point to launched in arbitrary direction ray, judge ray with The intersection point number of solid, odd number be it is interior, even number is then put in outside.

(5.4) photon outgoing and collection of energy.Continuously photon, photon and scatterer is generated according to above-mentioned process to collide (energy loss) and the track for tracking photon, we will scatter energy to it and count after photon leaves scatterer.

The photon for being 1 equipped with N number of energy is launched, and has M photon to escape from cloud cluster through continuous collision, and scattering direction is respectivelySelf-contained energy is respectively I_i, to the total spaceTo grid dividing is carried out, the step-length at the angle θ is Δ θ,Angle Step-length beCan simply the coordinate system shown in Figure 22 indicate, at the same have θ=m Δ θ,Judge emergent light SonThe method for whether entering (m, n) unit is:

Then, InTotal photon energy that direction receives are as follows:

(5) further, to data progress complex operation is solved, required polarization data is obtained comprising the steps of: see In the definition of above-mentioned stokes vector, radar cross section, In can be calculated in the following wayDirection Radar cross section can indicate are as follows:

Application effect of the invention is explained in detail below with reference to emulation.

One, simulated conditions: emulation uses different distributions normal state wake flow chaff cloud, and parameter is as shown in table 6, and different wave beams makes Generated with different antenna, chaff cloud as source point (as shown in Figure 8), a kind of possible antenna direction diagram form as shown in figure 9, The positional relationship of antenna and chaff cloud is as shown in Figure 10.

6 experiment condition list of table

Two, emulation content and result

Emulation 1, using No. 1 experiment parameter in table 5, as a result as shown in Figure 11~Figure 14, show here it is single, double stand as a result, Wherein Figure 11 is the Energy distribution of the source plane of departure, and Figure 12 is the EM scattering characteristic of chaff cloud, and Figure 13~Figure 14 is a section H Polarization and V polarimetric radar scattering section are compared with measured result, and two kinds of polarisation errors are within 10%.

Emulation 2, using No. 2 experiment parameters in table 5, as a result as shown in Figure 15~Figure 18, show here it is single, double stand as a result, Wherein Figure 15 is the Energy distribution of the source plane of departure, and Figure 16 is the EM scattering characteristic of chaff cloud, and Figure 17~Figure 18 is a section H Polarization and V polarimetric radar scattering section are compared with measured result, and two kinds of polarisation errors are within 15%.

Emulation 3, using No. 3 experiment parameters in table 5, as a result as shown in Figure 19~Figure 22, show here it is single, double stand as a result, Wherein Figure 19 is the Energy distribution of the source plane of departure, and Figure 20 is the EM scattering characteristic of chaff cloud, and Figure 21~Figure 22 is a section H Polarization and V polarimetric radar scattering section are compared with measured result, and two kinds of polarisation errors are within 13%.

Emulation 4, using No. 4 experiment parameters in table 5, as a result as shown in Figure 23~Figure 26, show here it is single, double stand as a result, Wherein Figure 23 is the Energy distribution of the source plane of departure, and Figure 24 is the EM scattering characteristic of chaff cloud, and Figure 25~Figure 26 is a section H Polarization and V polarimetric radar scattering section are compared with measured result, and two kinds of polarisation errors are within 10%.

Below with reference to experiment to the detailed description of application effect of the invention.

System performance is assessed by a series of experiment simulation, the scattering of big scale of construction chaff cloud is calculated, At identical conditions, the comparing result of rarely seen open report, compares with measured result, and the error of above-mentioned four kinds of emulation exists Within 15%, due to industry disclose chaff cloud scattering calculate as a result, therefore applicability of the invention and accuracy it is all higher, for The big scale of construction chaff cloud effect of the present invention of simple types is more preferable.

Technical effect of the invention is explained in detail below with reference to comparison table.

7 typical model reliability demonstration of table

Serial number	Experiment condition	Calculated value/measured value	The present invention
				1	1000, square is uniformly distributed	-10dBsm	-12dBsm
2	1000, taper, non-uniform Distribution	0.5dBsm	0.9dBsm
				3	It is 100000, spherical, it is uniformly distributed	12.12dB	9.1dB

The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention Made any modifications, equivalent replacements, and improvements etc., should all be included in the protection scope of the present invention within mind and principle.

Claims

1. a kind of big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector, which is characterized in that described to be based on Big scale of construction chaff cloud electromagnetic scattering measuring method that outline vector transports the following steps are included:

Second step carries out multidomain treat-ment using K-means algorithm based on chaff cloud spatial distribution model, and uses line moment method meter Attenuation coefficient information in region needed for calculating vector radiative transfer theory；

Third step is based on partition data and acquired region self-energy attenuation coefficient, defeated to vector using monte carlo method Fortune equation is solved, and is emitted using virtual photon, is transported, collided, tracked, the method for receive process realizes that vector transports integral The rapid solving of equation equation；

4th step realizes HH, HV, VV, VH by Stokes vector or its transformation based on the solving result of vector transport equation The solution of polarization mode.

2. the big scale of construction chaff cloud electromagnetism Scattering Calculation method transported as described in claim 1 based on outline vector, feature It is, the big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector is put into slice type three-dimensional chaff cloud Diffusion model construction method includes:

(1) foundation of fluid mechanics equation, the movement diffusion equation based on the available chaff center position of N-S equation is such as Under:

(2) the speed field direction relied on its position is directed toward in the space of chaff, if the velocity field of certain root chaff position It can be expressed asThen define two three vectors:

And enable, θ be chaff orientation vector withThe angle of vector,It is chaff orientation vector in vectorThe plane opened Upper projection vector and vectorThe angle of positive direction, and have θ,Probability density function are as follows:

According to chaff central point generation strategy and chaff is generated by probability density at random to be orientated, and can establish aircraft wake influence Under chaff cloud spatial distribution model.

3. the big scale of construction chaff cloud electromagnetic scattering measuring method transported as described in claim 1 based on outline vector, feature It is, the big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector carries out Chaff Clouds spatial distribution number According to reading, and Chaff Clouds region division is carried out based on K-means algorithm and is comprised the steps of:

(2) in K-means algorithm K value determine cluster result in classification quantity, to chaff cloud classify foundation be chaff The distance between, the reversed distribution number density for reflecting chaff cloud different zones therebetween；Chaff cloud subregion includes:

1. randomly choosing K central point in the point model of chaff center；

2. traversing all chaff cloud space center point data, each chaff central point is attributed to K and is drafted corresponding to central point Classification in；

4. the big scale of construction chaff cloud electromagnetic scattering measuring method transported as described in claim 1 based on outline vector, feature It is, the big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector uses random sampling in each subregion Algorithm extracts adjacent a small amount of chaff using line moment method MoM and calculates the polar transmission loss that electromagnetic wave is propagated in the area, and Database is established, comprising the following steps:

(1) the subsequent chaff required using MoM calculating is determined using discrete event sampling algorithm in each subregion, specifically include Following steps:

N (i)=unrand (1, M_i)；

Wherein, function unrand (1, M_i) can be randomly generated according to being uniformly distributed more than or equal to 1 and less than or equal to M_iPositive integer N (i), label i is the call number in region, M_iIndicate ith zone chaff total quantity；

3. calculating the Q root foil electromagnetic scattering selected using line moment method is divided into T sections as a result, setting every chaff, at each section Upper definition Basis Function:

Wherein, x_mFor m sections of midpoint, Δ x_mFor m sections of length；Then all chaff electric currents can indicate are as follows:

Wherein, α_nIt is undetermined coefficient,It is defined on n-th section, is zero in other sections, when chaff is perfact conductor or PEC, Following improved Electric Field Integral Equation can be established on chaff surface:

Wherein,WithRespectively site and source point,It for incidence wave electric field strength, is tested, is obtained using Galerkin method It arrives:

Wherein, L is integral equation linear operator, establishes matrix equation:

[l_mn][α_n]=[g_m]；

Wherein:

κ=- n σ；

Wherein, n is the number density of unit volume chaff, for different subregions, is calculated using identical method；

Wherein,Indicate the vertically and horizontally component of scattered field,Indicate hanging down for in-field Straight and horizontal component.

5. the big scale of construction chaff cloud electromagnetic scattering measuring method transported as described in claim 1 based on outline vector, feature It is, the big scale of construction chaff cloud electromagnetic scattering measuring method transported based on outline vector is based on Delaunay algorithm to above-mentioned Each subregion carries out triangulation and external envelope is established, and establish different zones each triangular apex of external envelope, normal vector, Central point index list, establishes database, comprising the following steps:

1. selecting a chaff central distribution point P₁As the first vertex of triangle, distance P is selected₁Nearest chaff distributed point conduct Second vertex of triangle, is denoted as P₂；

2. selecting the third vertex P of triangle₃, make itself and P₁、P₂Without other vertex in the circumscribed circle of the triangle of composition, Also, vertex P in the triangle₃The interior angle opened is maximum；

4. select one from list, the corresponding flag bit in side will be changed and be set as 0；One is searched for from remaining spatial point list Meet: first, this is in the opposite side of side institute third point in the triangles, second, the triangle of the point and side composition outside Connecing in circle does not have other points, meet the point of the above-mentioned condition subtended angle in new triangle it is maximum that as P₃；

5. if being added into side table tail, and set the flag bit on newly-generated side as 0 when there is no newborn in 4. in list；Such as Fruit has existed, then the flag bit that these sides are arranged is 1, and triangle table is added in the triangle of generation, by what is selected from 4. That side flag bit is set as 1；The process is gone to 1., until the flag bit on all sides is 1；

(2) three-dimensional Delaunay algorithm realizes step substantially:

It being taken a bit 1. appointing in chaff spatial distribution point, and finds and put nearest point apart from this, connection two o'clock constitutes initial baseline, Third point is found using triangulation criterion, forms initial Delaunay triangle；

2. extended triangular grid is found and this 3 using 3 sides of initial delta as initial baseline using external empty ball criterion 3 points of initial baseline formation Delaunay triangulation network；

x_max, x_min, y_max, y_min, z_max, z_min；

And carry out subdivision using cuboid in space, the side length on three directions of each square be (Δ x, Δ y, Δ z), in It is the central point of each cubical area are as follows:

And

Wherein, ceil () function representation rounds up number；

2. since external envelope point is only possible to contraction algorithm can be used, from the outside to the core there are in the grid on the outside of cuboid Each layer of box is searched for, is stopped in the presence of encountering box a little；

(4) external envelope triangulation exterior normal direction is determined, using continuously facing normal orientation calculation criterion outside side, if two adjacent three Angular vertex is respectively A, B, C and B, C, D；And m is set, n, p are the 1st Atria vertex serial numbers, and w, g, h is the 2nd triangle Three vertex of shape, sequence according to right-hand screw rule and from small to large calculate the 1st triangulation method vector are as follows:

If the label on three vertex of the 2nd triangle arrives from childhood is followed successively by one of BDC, CBD, DCB greatly, under so continuing It goes, numbers all triangular apex, then each triangle is in circulation, as long as can determine exterior normal according to the right-hand rule Direction, the algebraic average that three apex coordinates can be used for external envelope center point coordinate calculate.

6. the big scale of construction chaff cloud electromagnetic scattering measuring method transported as described in claim 1 based on outline vector, feature It is, it is described that model vector transport equation is established based on the big scale of construction chaff cloud electromagnetic scattering measuring method that outline vector transports, And the equation is solved using monte carlo method comprising the steps of:

(1) consider antenna radiation pattern source plane generate, which is the premise and basis of subsequent vector transport theory, comprising with Lower step:

Wherein, the central point of source plane is selected as:

3. Fibonacci grid is used, and its sampled point in the external envelope generating source plane generated, in the plane of source under The mode in face defines coordinate system:

And it is its is unitization:

The position vector for remembering each vertex of external envelope is (x_i,outline,y_i,outline,z_i,outline), by it in arrow defined above It projects, finds in amountWithThe circle that may include all external envelope points is found in dimension plane, remembers that its radius is R_min, then make It can produce grid with Fibonacci grid policies are as follows:

4. according to directivity function and the discrete event methods of sampling, just source emits point sampling, is located in specified external envelope using luxuriant and rich with fragrance The thermogenetic discrete point of Fibonacci net is P (i), and the normalized radiation pattern value that each pair of point is answered is Q (i), then can be according to following Mode generating source sampling；

Calculate cumulative probability:

A random number is generated according to being uniformly distributed:

Randnumber=rand ()；

Wherein, function can produce the random number in [0,1] section；If M (m)≤randnumber≤M (m+1), is extracted Source point serial number m, corresponding coordinate are P (m)；

(2) source transmitting photon intersects judgement with the outer triangulation face of chaff cloud；Extract source point:

P (m)=(x_sm,y_sm,z_sm)；

And the direction of propagation of known incident wave are as follows:

Then write out the linear equation of Particles Moving are as follows:

X=x_sm+t·n_x, y=y_sm+t·n_y, z=z_sm+t·n_z；

Wherein, t is parameter；

The straight line expression formula derived is substituted into obtain:

λ₁(TR₁-TR₂)+λ₂(TR₁-TR₃)+tn_xn_yn_z=TR₁-Pm)；

It writes a Chinese character in simplified form are as follows:

λ₁a+λ₂B+tc=d；

Write as matrix form are as follows:

Solution are as follows:

If λ₁,λ₂∈ [0,1], then ray and chaff cloud external envelope have intersection point, when there is multiple intersection points, need using minimum t method Then judge the first intersection point；

(3) photon is transmitted in chaff cloud according to probability, is solved vector transport equation using monte carlo method and is realized, if n root Chaff is randomly dispersed in a length of ds, and volume is in the cylindricality body unit of dv, and the electromagnetic wave that a radiation intensity is I passes through the unit, By the variable quantity of the available electromagnetic wave radiant intensity of law of conservation of energy are as follows:

Wherein,It is incident intensityAnd scattering strengthBetween transfer coefficient or matrix, the first of above formula Item refers to absorbing κ due to chaff_as, scattering κ_s, background absorption κ_abCaused energy dissipation, Section 2 indicate be space other The energy of source radiation is radiated, what Section 3 indicated is that multiple scattering body coupling scattering existsScattering strength summation on direction, in which:

κ_ab=2k " (1-f_s), k " is wave numberImaginary part；

Here four Stokes vectors sanctified by usage are introduced:

1. free path is sampled, the step of passing through front, available photon enters the specific location of chaff cloud for the first time, and according to Following free path formula is sampled, and obtains the walked distance of next impinging photon:

2. chaff orientation sampling, the orientation of chaff is by Space AngleIt determines, if the probability density function that they are obeyed is p (θ) WithScattering direction is extracted using rejection technique；

Firstly, in θ ∈ [0, π],Between according to be uniformly distributed extract the chaff angle of orientationI.e. just like following formula Son:

ξ is the uniform random number between [0,1]；

Bring the chaff angle of orientation into probability density function

Secondly, InA uniform random number P is generated again using above-mentioned ξ on section₀, under The judgment criterion in face carries out angle of departure selection:

If what above-mentioned criterion provided is refusalSelection, which then needs to return to the first step, to be continued, and is met the requirements until generating Several pairs until；

3. scattering direction sampling；It is scattered direction sampling based on the conservation of energy and rejection technique, is located at the incidence angle of a certain determinationUnder, the energy of scattering is written as:

And:

Wherein, it indicatesDirection scattering coefficient, is defined:

Firstly, in θ ∈ [0, π],Between according to being uniformly distributed the extraction angle of departureThere is following formula:

ξ is the uniform random number between [0,1]；

Bring the launch angle of calculating into probability density functionHave:

If what above-mentioned criterion provided is " refusalSelection ", which then needs to return to the first step, to be continued, until generating satisfaction It is required that several pairs until；

4. scattering transmission energy harvesting, calculates the decay factor collided every time, under the conditions of given incidence wave, whole scattered fields Energy is written as:

Repeat it is above-mentioned 1.~4. until photon projects chaff cloud, accumulate enough photons and just carry out subsequent data processing, sentence Whether the primitive decision method inside and outside cloud is disconnected photon, from the point to launched in arbitrary direction ray, judges ray and solid Intersection point number, odd number be it is interior, even number is then put in outside；

(4) photon outgoing and collection of energy, continuously according to process generate photon, photon and scatterer collide and track photon Track, energy will be scattered to it after photon leaves scatterer and counted；

Then, InTotal photon energy that direction receives are as follows:

Complex operation is carried out to data are solved, obtains required polarization data comprising the steps of: count in the following way Calculate radar cross section, InThe radar cross section in direction indicates are as follows:

7. a kind of using the big scale of construction chaff cloud electromagnetic scattering transported described in claim 1~6 any one based on outline vector The radar of measuring method.