Method for determining complex amplitude of scattering center in target near-field scattering center modeling

Abstract

The invention provides a method for determining the complex amplitude of a scattering center in target near-field scattering center modeling, and relates to the technical field of complex target scattering center modeling. The method comprises the following steps: establishing a mathematical coordinate system for a target; determining a position vector of each scattering center of the target based on the established mathematical coordinate system; determining a normalized near-field scattering field of each scattering center of the target in the observation area based on the determined position vector of each scattering center of the target; determining a normalized near-field scattered field of the target in the observation area; and determining the complex amplitude of each scattering center of the target according to the determined normalized near-field scattered field of each scattering center of the target in the observation area and the normalized near-field scattered field of the target in the observation area. Therefore, the total near-field scattering field of all the scattering centers on the near-field observation area can be maximally similar to the real near-field scattering field of the target, so that the scattering center amplitude can be quickly and accurately determined.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of complex target scattering center modeling, and particularly relates to a method for determining the complex amplitude of a scattering center in target near-field scattering center modeling. BACKGROUND

[0002] Radar detection of a target is based on the scattering characteristics of the target. When electromagnetic waves are incident on the surface of the target, a current is excited on the surface of the target, and the current generates a scattering field that is received by the radar to achieve detection of the target. Therefore, the scattering field of the target is of great significance to the detection and identification of the target. One basic parameter describing the characteristics of the target is the radar cross section (RCS). However, with the advancement of radar technology, a single RCS parameter is insufficient to describe the distribution characteristics of the target scattering field in space. Therefore, the use of scattering centers to describe the scattering characteristics of the target has become the focus of research. At present, research on target scattering centers has made sufficient progress and achieved a large number of results. However, most of these results are directed to the far-field scattering characteristics of the target. That is, the radar irradiates the target from the far-field region. At this time, the electromagnetic waves incident on the target can be modeled as a uniform plane wave. Similarly, the target scattering field in the radar receiving region can also be modeled as a uniform plane wave. The scattering center model at this time is a far-field scattering center. Such scattering center model parameters, under near-field working conditions, will not be able to describe the actual near-field conditions of the target scattering field with the expected accuracy. Under near-field conditions, the incident direction and polarization direction of the electromagnetic wave are no longer parallel, the propagation path of the scattering field no longer satisfies the far-field approximation condition, and the influence of the antenna pattern needs to be considered. Therefore, there is a great difference between the scattering solution of the target under the near-field condition and the far-field condition, and the existing scattering center model is no longer applicable. The scattering center model under the near-field condition will be more complex. Therefore, it is necessary to further improve the far-field scattering center model to a more general near-field scattering center model. The near-field scattering center type can be divided into multiple types, among which the distributed scattering center is an important type. For the distributed scattering center, it can be further divided into a planar type, a single curved surface type, an edge diffraction type, and the like. In the process of near-field modeling of the scattering center, a large amount of analysis and calculation work is required to determine the amplitude of the radiation field of the scattering center. When the near-field scattering center model of a complex target is built, the amplitude values of the corresponding scattering centers are difficult to directly obtain due to the fact that the scattering field of the target is mixed with multiple attribute scattering centers and the scattering fields of multiple scattering centers. Therefore, the present application aims to solve this problem from the maximum likelihood of the total near-field scattering field of all scattering centers and the real near-field scattering field of the target. SUMMARY

[0003] To solve the technical problem that it is difficult to directly obtain the amplitude value of the corresponding scattering center when modeling the near-field scattering center of a complex target in the prior art, an embodiment of the present application provides a method for determining the complex amplitude of a scattering center in target near-field scattering center modeling.

[0004] In one aspect, a method for determining the complex amplitude of a scattering center in target near-field scattering center modeling is provided, comprising:

[0005] establishing a mathematical coordinate system for the target;

[0006] determining the position vector of each scattering center of the target based on the established mathematical coordinate system;

[0007] determining the normalized near-field scattering field of each scattering center of the target in the observation region based on the determined position vector of each scattering center of the target;

[0008] determining the normalized near-field scattering field of the target in the observation region;

[0009] determining the complex amplitude of each scattering center of the target according to the determined normalized near-field scattering field of each scattering center of the target in the observation region and the normalized near-field scattering field of the target in the observation region.

[0010] Further, the establishment of the mathematical coordinate system for the target comprises:

[0011] establishing an xyz rectangular coordinate system with a point on the target as the coordinate origin; wherein the horizontal plane is the xy plane, the longitudinal axis direction and the transverse axis direction of the target are the x direction and the y direction respectively, and the coordinates of the N scattering centers of the scattering center model of the target are (x i ,y i ,z i ), z i >>x i ,y i , i = 1,..., i,..., N.

[0012] Further, the determination of the position vector of each scattering center of the target based on the established mathematical coordinate system comprises:

[0013] determining the position vector of each scattering center of the target based on the established mathematical coordinate system, wherein the position vector of the i-th scattering center of the target is:

[0014] r i =(x i ,y i ,z i )i = 1, 2,..., N

[0015] wherein r ia position vector of the i-th scattering center of the target.

[0016] Further, the normalized near-field scattering field of the i-th scattering center of the target in the observation region is determined based on the determined position vector of the i-th scattering center of the target.

[0017] According to the electromagnetic scattering theory, the normalized near-field scattering field E i0 of the i-th scattering center of the target in the observation region is determined as follows: i0

[0018]

[0019] where f represents the frequency; θ represents the radar elevation angle; φ represents the radar azimuth angle; R0 represents the radar-target distance, which is determined by the position vector r i of the i-th scattering center of the target; λ represents the radar operating wavelength; A near (·) represents the near-field correction factor; j represents the imaginary unit; k represents the wave number; e p represents the polarization direction.

[0020] Further, the near-field correction factor A near (f, θ, φ, R0) is expressed as follows:

[0021]

[0022]

[0023]

[0024]

[0025] where g0(·) and g1(·) are intermediate expressions; α and β represent function variables, the value of α is α c , α s , and the value of β is β c , β s ; F(·) is the Fresnel integral formula; 2a and 2b are the side lengths of the rectangular plane.

[0026] Further, the complex amplitude of the i-th scattering center of the target is expressed as follows:

[0027]

[0028] where A N represents the amplitude of the N-th scattering center, η represents the power factor, and E i0 represents the normalized near-field scattering field E​i0 , E t0 represents the normalized near-field scattering field of the target in the observation region, and D(·) represents a difference measure function of the near-field scattering field.

[0029] Further, the function D(·) is in the form of:

[0030]

[0031] wherein S is the observation region, the superscript * represents conjugation, and p and q both represent the near-field scattering field.

[0032] In another aspect, a computer-readable storage medium is provided, the storage medium having stored therein at least one instruction, the at least one instruction being loaded and executed by a processor to implement any one of the methods for determining the complex amplitude of a scattering center in target near-field scattering center modeling.

[0033] The technical solutions provided by the embodiments of the present application have at least the following beneficial effects:

[0034] 1. The total near-field scattering field of all scattering centers on the near-field observation region can be maximally similar to the real near-field scattering field of the target, so that the scattering center amplitude can be obtained more quickly and accurately; and 2. The near-field scattering center modeling accuracy of a complex target can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0036] Figure 1 is a flowchart of a method for determining the complex amplitude of a scattering center in target near-field scattering center modeling provided by the embodiments of the present application;

[0037] Figure 2 is a schematic diagram of a target xyz rectangular coordinate system provided by the embodiments of the present application;

[0038] Figure 3 is a schematic diagram of a rectangular planar structure provided by the embodiments of the present application. DETAILED DESCRIPTION

[0039] The technical solutions in the present application will be described below with reference to the drawings.

[0040] In the embodiments of the present application, the words such as "exemplary", "for example", etc. are used to represent an example, illustration or description. Any embodiment or design scheme described as "exemplary" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the word "exemplary" is intended to present the concept in a specific manner. In addition, in the embodiments of the present application, the meaning expressed by "and / or" can be both, or can be one of the two.

[0041] In the embodiments of the present application, "image" and "picture" can be used interchangeably at times, and it should be pointed out that the meanings expressed are consistent when the distinction is not emphasized. "Of", "corresponding" and "corresponding" can be used interchangeably at times, and it should be pointed out that the meanings expressed are consistent when the distinction is not emphasized.

[0042] In the embodiments of the present application, sometimes the subscript such as W1 can be written in the form of non-subscript such as W1, and the meanings expressed are consistent when the distinction is not emphasized.

[0043] In order to make the technical problems, technical schemes and advantages to be solved by the present application more clear, the following will be described in detail in combination with the drawings and specific embodiments.

[0044] The embodiments of the present application provide a method for determining complex amplitudes of scattering centers in target near-field scattering center modeling, as shown in Figure 1 The processing flow of the method can include the following steps:

[0045] S1, establishing a mathematical coordinate system for the target;

[0046] In the present embodiment, a point on the target (for example, a point at the front end of the target) is taken as the coordinate origin to establish an xyz rectangular coordinate system, as shown in Figure 2 ; wherein the horizontal plane is taken as the xy plane, the target longitudinal axis direction and the transverse axis direction are taken as the x direction and the y direction respectively, and the coordinates of the N scattering centers of the scattering center model of the target are (x i ,y i ,z i ), respectively, z i >>x i ,y i , i = 1,...i,...N, Figure 1 , wherein represents the radar elevation angle, represents the radar azimuth angle, and LOS is the direct path.

[0047] S2, determining the position vectors of the scattering centers of the target based on the established mathematical coordinate system;

[0048] In the embodiment, based on the established mathematical coordinate system, the position vector of each scattering center of the target is determined, wherein the position vector of the i-th scattering center of the target is:

[0049] r i i i i i = 1, 2, …, N

[0050] wherein r i is the position vector of the i-th scattering center of the target.

[0051] S3, based on the determined position vector of each scattering center of the target, the normalized near-field scattering field of each scattering center of the target in the observation area is determined.

[0052] In the embodiment, according to the electromagnetic scattering theory, the normalized near-field scattering field E i0 of the i-th scattering center of the target in the observation area is determined; wherein for the distributed scattering center of the rectangular plane structure (for example, the planar structure on the airplane, such as the wing), the scattering field E i0 is expressed as:

[0053]

[0054] wherein f represents the frequency; θ represents the radar elevation angle; φ represents the radar azimuth angle; R0 represents the radar-target distance, which is determined by the position vector r i of the i-th scattering center of the target; λ represents the radar operating wavelength; A near (·) represents the near-field correction factor; j represents the imaginary unit; k represents the wave number; e p is the polarization direction.

[0055] In the embodiment, the near-field correction factor A near (f, θ, φ, R0) is expressed as:

[0056]

[0057]

[0058]

[0059]

[0060] wherein g0(·), g1(·) are both intermediate expressions; α, β both represent function variables, the value of α is α c , α s , and the value of β is β c , β s ​​​; F(·) is a Fresnel integral formula; 2a and 2b are the side lengths of the rectangular plane, as shown in Figure 3 When the above formula is used to calculate the plane near-field scattering, the center of the rectangular plane should be located at the origin of the xyz rectangular coordinate system, and the edges should be parallel to the X axis and the Y axis.

[0061] S4, determining the normalized near-field scattering field of the target in the observation region;

[0062] In this embodiment, the normalized near-field scattering field E t0 of the complex target in the observation region is obtained through electromagnetic calculation.

[0063] S5, determining the complex amplitude of each scattering center of the target according to the normalized near-field scattering field of each scattering center of the target in the observation region and the normalized near-field scattering field of the target in the observation region.

[0064] In this embodiment, the complex amplitude of each scattering center of the target is represented as:

[0065]

[0066] wherein A N represents the amplitude of the Nth scattering center, η represents a power factor, E i0 represents the normalized near-field scattering field E i0 of the i th scattering center of the target in the observation region, and E t0 represents the normalized near-field scattering field of the target in the observation region, and D(·) represents a difference measurement function of the near-field scattering field.

[0067] In this embodiment, the function D(·) has the form:

[0068]

[0069] wherein S is the observation region, specifically the effective spatial region of the scattering center model; the superscript * represents conjugation; and p and q both represent the near-field scattering field.

[0070] In this embodiment, through the calculation formula of the complex amplitude of each scattering center, the maximum similarity between the total near-field scattering field of all scattering centers in the near-field observation region and the real near-field scattering field of the target can be achieved, so that the amplitude of the scattering center that makes the field distribution in the observation region have the maximum similarity, i.e., the complex amplitude, can be obtained more quickly and accurately.

[0071] In this embodiment, modeling based on the obtained complex amplitude of each scattering center of the target can improve the accuracy and speed of near-field scattering center modeling.

[0072] The method for determining the complex amplitude of the scattering center in the modeling of the near-field scattering center of a target provided by the embodiments of the present invention has at least the following beneficial effects:

[0073] 1. It can achieve the maximum similarity between the total near-field scattering field of all scattering centers in the near-field observation area and the actual near-field scattering field of the target, thus enabling the amplitude of the scattering center to be obtained more quickly and accurately;

[0074] 2. It can improve the modeling accuracy of near-field scattering centers of complex targets.

[0075] The above embodiments can be implemented, in whole or in part, by software, hardware (such as circuits), firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0076] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0077] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0078] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0079] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0080] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0081] In the several embodiments provided by this invention, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0082] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0083] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0084] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0085] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for determining the complex amplitude of the scattering center in modeling the near-field scattering center of a target, characterized in that, The method includes: Establish a mathematical coordinate system for the target; Based on the established mathematical coordinate system, the position vectors of each scattering center of the target are determined; Based on the determined position vectors of each scattering center of the target, the normalized near-field scattering field of each scattering center of the target in the observation area is determined. Determine the normalized near-field scattering field of the target in the observation area; Based on the normalized near-field scattering fields of each scattering center of the target in the observation area and the normalized near-field scattering field of the target in the observation area, the complex amplitude of each scattering center of the target is determined.

2. The method for determining the complex amplitude of the scattering center in the target near-field scattering center modeling according to claim 1, characterized in that, Establishing a mathematical coordinate system for the target includes: Establish an xyz rectangular coordinate system with a point on the target as the origin; where the horizontal plane is the xy plane, the longitudinal axis direction and the transverse axis direction of the target are the x and y directions, respectively, and the coordinates of the N scattering centers of the target's scattering center model are (x... i ,y i ,z i ), z i >>x i ,y i , i = 1, ... i, ... N.

3. The method for determining the complex amplitude of the scattering center in the target near-field scattering center modeling according to claim 2, characterized in that, The determination of the position vectors of each scattering center of the target based on the established mathematical coordinate system includes: Based on the established mathematical coordinate system, the position vectors of each scattering center of the target are determined, where the position vector of the i-th scattering center of the target is: r i =(x i ,y i ,z i )i=1,2,...,N Where, r i Let be the position vector of the i-th scattering center of the target.

4. The method for determining the complex amplitude of the scattering center in the near-field scattering center modeling of a target according to claim 1, characterized in that, The process of determining the normalized near-field scattering field of each scattering center of the target in the observation area based on the determined position vectors of each scattering center of the target includes: Based on electromagnetic scattering theory, the normalized near-field scattering field E of the i-th scattering center of the target in the observation area is determined. i0 Among them, for the distributed scattering center of the rectangular planar structure, the scattered field E i0 Represented as: Where f represents the frequency; θ represents the radar elevation angle; φ represents the radar azimuth angle; R0 represents the distance from the radar to the target, derived from the position vector r of the i-th scattering center of the target. i Determined; λ represents the radar operating wavelength; A near (·) represents the near-field correction factor; j represents the imaginary unit; k represents the wavenumber; e p This indicates the polarization direction.

5. The method for determining the complex amplitude of the scattering center in the near-field scattering center modeling of a target according to claim 4, characterized in that, Near-field correction factor A near (f,θ,φ,R0) is represented as: In this context, g0(·) and g1(·) are intermediate expressions; α and β both represent function variables, with α taking the value of α. c α s The value of β is β c β s ;F(·) is the Fresnel integral formula; 2a and 2b are the side lengths of the rectangular plane.

6. The method for determining the complex amplitude of the scattering center in the near-field scattering center modeling of a target according to claim 1, characterized in that, The complex amplitude of each scattering center of the target is expressed as: Among them, A N E represents the amplitude of the Nth scattering center, η represents the power factor, and E i0 E represents the normalized near-field scattering field E of the i-th scattering center of the target in the observation area. i0 E t0 D(·) represents the normalized near-field scattering field of the target in the observation area, and D(·) represents the difference measure function of the near-field scattering field.

7. The method for determining the complex amplitude of the scattering center in the near-field scattering center modeling of a target according to claim 6, characterized in that, The function D(·) has the following form: Where S represents the observation area, the superscript * indicates conjugate, and p and q both represent the near-field scattering field.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium contains program code that can be invoked by a processor to execute the method as described in any one of claims 1 to 7.

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