An echo generation method based on an attribute scattering center near-field correction model

Abstract

The application provides an echo generation method based on an attribute scattering center near field correction model, containing the following steps: S1, inputting parameters of an attribute scattering center far field model; S2, correcting the far field scattering field amplitude and phase of the LSC based on the radar parameters in the near field, the position relationship between the LSC and the radar, and obtaining a local type scattering center near field correction model; S3, dividing the DSC into multiple segments, searching the segments and the observed regions of the DSC observed by the radar under each radar line of sight angle; S4, correcting the far field scattering field amplitude of the DSC through a step response function; S5, correcting the far field scattering field phase of the DSC under each radar line of sight angle, and obtaining a distributed type scattering center near field correction model in combination with the number of segments of the DSC observed; S6, generating the near field scattering echo of the target under the current radar position based on the attribute scattering center near field correction model, changing the radar position, and repeating S2 to S6.

Description

Technical Field

[0001] This invention relates to the field of radar electromagnetic simulation technology, and in particular to an echo generation method based on a near-field correction model of attribute scattering center. Background Technology

[0002] When radar observes a target, if the radar distance is sufficiently far, the electromagnetic waves emitted by the radar can be considered uniform plane waves, and the target's scattered echo exhibits far-field scattering characteristics. However, in many scenarios, the radar's observation range is limited, and the electromagnetic waves emitted by the radar are non-uniform spherical waves. In this case, the target's scattered echo exhibits near-field scattering characteristics. The echo characteristics of the target under near-field conditions differ significantly from those under far-field conditions and exhibit dynamic characteristics that vary with radar distance. Therefore, accurate simulation of the target's scattered echo under near-field conditions is a continuously researched and hotly debated issue in the field of electromagnetic computation, possessing high academic value and application prospects.

[0003] In existing research, both the full-wave method and the high-frequency approximation method have been used to calculate the near-field electromagnetic scattering of targets. The full-wave method provides accurate results but is very time-consuming, while the high-frequency method is computationally efficient and accurate, but still requires considerable computation time. However, the main applications of near-field scattering simulation include target tracking by missile-borne radar and real-time early warning by vehicle-mounted radar. These scenarios require real-time simulation of the target's near-field scattering, and the aforementioned methods cannot fully meet the needs of engineering applications. For example, in missile-borne radar detection, the radar rapidly approaches the target, and the echo exhibits near-field scattering characteristics that change dynamically. Therefore, it is necessary to solve the problem of real-time simulation of target near-field scattering in order to predict changes in the target's near-field scattering characteristics and provide support for target identification and tracking during missile-target encounters. Summary of the Invention

[0004] The purpose of this invention is to provide an echo generation method based on a near-field correction model of the attribute scattering center, in order to solve the problem of rapid simulation of scattering echoes of electrically large targets under near-field conditions. While ensuring accuracy, it reduces simulation calculation costs, improves simulation calculation efficiency, and has a wide-angle advantage, which can be used for target tracking and identification of missile-borne radar and early warning of vehicle-borne radar.

[0005] To achieve the above objectives, this invention provides an echo generation method based on a near-field correction model of attribute scattering centers. The electrically large target has multiple local scattering centers and multiple distributed scattering centers. The method includes the following steps:

[0006] S1, parameters of the far-field model of the property scattering center of electrically large targets;

[0007] S2. Input radar parameters when the radar is in the near field; obtain the positional relationship between the local scattering center and the radar, and based on the positional relationship, correct the amplitude and phase of the far-field scattering field of the local scattering center to the corresponding amplitude and phase of the near-field scattering field, and obtain the near-field correction model of the local scattering center;

[0008] S3. Divide the distributed scattering center into multiple segments; search for all segments of the distributed scattering center that are observed by the radar at each radar line of sight angle, and all segments constitute the observed area of ​​the distributed scattering center at that radar line of sight angle.

[0009] S4. By using the step response function, the amplitude of the far-field scattering field of the distributed scattering center is corrected to the corresponding amplitude of the near-field scattering field.

[0010] S5. Based on the positional relationship between the center point of the observed area corresponding to the distributed scattering center and the radar under the corresponding radar line-of-sight angle, the phase of the far-field scattering field of the distributed scattering center under the radar line-of-sight angle is corrected to the phase of the corresponding near-field scattering field; based on the amplitude, phase and number of observed segments of the near-field scattering field of the distributed scattering center under each radar line-of-sight angle, the near-field correction model of the distributed scattering center is obtained.

[0011] S6. The local scattering center near-field correction model and the distributed scattering center near-field correction model are summed to obtain the attribute scattering center near-field correction model; the near-field scattering echo of the electrically large target at the current radar position is obtained based on the attribute scattering center near-field correction model; the radar position is changed, and S2 to S6 are repeated to obtain the near-field scattering echo at different radar positions.

[0012] Optional, the attribute scattering center far-field model includes: local scattering center far-field model E LSC and the far-field model of the distributed scattering center E DSC ;

[0013]

[0014] Where i represents the i-th local scattering center, Num_LSC represents the total number of local scattering centers, and A i Let f be the amplitude of the far-field scattered field at the i-th local scattering center, and f be the frequency of the incident electromagnetic wave. c To model the center frequency, α is the frequency dependence factor, φ is the radar azimuth angle, and γ is the center frequency. i φ i ′ represents a parameter to be estimated that has no physical meaning, φ 1i φ 2i W(φ) represents the minimum and maximum visible angles of the i-th local scattering center, respectively. 1i ,φ 2i) is the window function, and k is the wave number. Let be the position vector of the i-th local scattering center. The radar line-of-sight vector for the local scattering center;

[0015] The input parameters for the local scattering center far-field model include: A i γ i φ i ′、φ 1i φ 2i α;

[0016]

[0017] Where m represents the m-th distributed scattering center, Num_DSC represents the total number of distributed scattering centers, and B m Let L be the amplitude of the far-field scattered field of the m-th distributed scattering center. m Let φ′ be the length of the m-th distributed scattering center. m It is the angle at which the m-th distributed scattering center appears, and F(φ) is the Gaussian window function. Let m be the position vector of the m-th distributed scattering center. The radar line-of-sight vector for the distributed scattering center;

[0018] The input parameters for the distributed scattering center far-field model include: B m L, φ′ m , α.

[0019] Optionally, the radar parameters include: the elevation angle and azimuth angle of the radar relative to the electrically large target, the straight-line distance between the radar and the center of the electrically large target, the radar antenna pattern data, and the radar frequency.

[0020] Optionally, the amplitude of the near-field scattered field of the i-th local scattering center in step S2 is denoted as A. i_near , Where G is the radar antenna gain, D is the maximum value of multiple one-dimensional lengths of electrically large targets in multiple dimensions, and λ is the radar wavelength.

[0021] The phase of the near-field scattered field of the i-th local scattering center is in The position vector of the local scattering center. This is the radar's position vector;

[0022] Local scattering center near-field correction model E LSC_near The expression is:

[0023]

[0024] Optionally, in step S3, the distributed scattering center is divided into L0 / λ segments; where L0 is the length of the electrically large target and λ is the radar wavelength.

[0025] Optionally, if the angle between the radar line-of-sight vector and the normal vector at the midpoint of the segment is less than 1.25°, then the segment can be observed by the radar.

[0026] Optionally, the step response function in step S4 is:

[0027]

[0028] B m_near Let be the amplitude of the near-field scattered field of the m-th distributed scattering center; GRCS is the generalized radar cross section in the near field of the distributed scattering center. R is the straight-line distance between the radar and the center of the electrically large target;

[0029] Where, a = 0.992B′ m , B′ m For B m The value after taking the logarithm.

[0030] Optionally, step S5 includes:

[0031] S51. Calculate the near-field scattering field E of the m-th distributed scattering center under the full radar line-of-sight angle. DSC_near_m :

[0032]

[0033] Where p represents the p-th radar line-of-sight angle; Num_angle is the total number of radar line-of-sight angles; d L_m n is the length of the segment of the m-th distributed scattering center; p,m It is the number of segments observed by the radar at the p-th radar line-of-sight angle for the m-th distributed scattering center; It is the position vector of the center point of the observed area of ​​the m-th distributed scattering center under the p-th radar line-of-sight angle;

[0034] S52, Near-field Correction Model of Distributed Scattering Center E DSC_near for:

[0035]

[0036] Optionally, the near-field correction model E of the property scattering center in step S6 near The expression is: E near =E LSC_near +E DSC_near .

[0037] Compared with existing technologies, the advantages of the echo generation method based on the near-field correction model of the attribute scattering center of the present invention are as follows:

[0038] 1) This invention is the first to propose a near-field correction to the far-field model of the attribute scattering center of electrically large targets, and generates the near-field echo of the target based on the corrected model. Compared with the existing technology that calculates the near-field echo of the target based on the point scattering center model, it has the advantage of a wide angle and can better characterize the scattering characteristics of the target.

[0039] 2) This invention, while ensuring accuracy, avoids extensive simulation calculations and can obtain near-field echo simulation results instantly. Therefore, it can be used for short-range radar detection in missile-target encounter scenarios, meeting the practical needs of missile-borne radar target tracking and identification, and vehicle-borne radar early warning. Therefore, compared to traditional methods, this invention has higher engineering application value. Attached Figure Description

[0040] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the drawings in the following description are one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0041] Figure 1 This is a geometric model diagram of the electrically large target in an embodiment of the present invention;

[0042] Figure 2 This is a flowchart of the echo generation method based on the near-field correction model of the attribute scattering center according to the present invention;

[0043] Figure 3 This is a schematic diagram of the illuminated area of ​​a target under near-field conditions in an embodiment of the present invention;

[0044] Figure 4 This is a comparison chart of near-field simulation results using the FEKO and property scattering center near-field correction models in an embodiment of the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0047] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0048] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0049] Furthermore, in the description of this application, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0050] The theoretical basis for target scattering simulation using the scattering center model originates from the high-frequency approximation method. When a target meets the high-frequency approximation conditions, the target's scattered field can be regarded as a linear superposition of echoes from several independent scattering centers. Using a parameterized scattering center model, the target's scattered field is approximated as a set of physically meaningful functions. The parameters of the scattering center model are related to physical quantities such as radar frequency and azimuth, and can be used to simulate the target's scattered echoes with high accuracy.

[0051] Current scattering center modeling methods are mainly applied to target scattering simulation under far-field conditions. Some literature uses SBR (shooting and bouncing ray) calculations to obtain the far-field scattering center of the target and uses this to predict the near-field scattering results. Other literature obtains two-dimensional and three-dimensional point scattering center models of the target using near-field ISAR (Inverse Synthetic Aperture Radar) imaging. Some literature addresses the problem of testing the RCS (Radar Cross Section) of electrically large-scale non-uniform plasma in vacuum, using near-field ISAR images and the CLEAN method to obtain a scattering center model, which is then extrapolated to far-field results. Some literature obtains the scattering center from near-field data and extrapolates it to far-field results. Still other literature obtains the target scattering center using the bouncing ray method and generates near-field dynamic echoes based on the near-field reconstruction formula of the point scattering center.

[0052] The existing technologies mentioned above all use point scattering center models, which have a small target detection range, complex calculation methods, and are time-consuming, and cannot meet the needs of scenarios such as missile-borne radar target tracking and identification, and vehicle-borne radar early warning.

[0053] Electrical size refers to the ratio of the maximum size of a target to the wavelength of the incident electromagnetic wave. When the electrical size is greater than 10, it can be considered an electrically large target. Figure 1 This is a geometric model diagram of the electrically large target in this embodiment of the invention. The electrically large target in this embodiment is a metal cube with dimensions of 1m × 1m × 0.2m. The electrically large target has multiple local scattering centers and multiple distributed scattering centers. According to the attribute scattering center modeling method (which is prior art and will not be elaborated here), the electrically large target in this embodiment has 4 local scattering centers and 3 distributed scattering centers. It should be noted that both the local scattering centers and the distributed scattering centers have a certain length.

[0054] This invention provides an echo generation method based on a near-field correction model of attribute scattering centers, such as... Figure 2 As shown, the steps include:

[0055] S1, parameters of the far-field model of the property scattering center of electrically large targets; the far-field model of the property scattering center includes: the local scattering center far-field model E. LSC and the far-field model of the distributed scattering center E DSC ;

[0056]

[0057] Where i represents the i-th local scattering center, Num_LSC represents the total number of local scattering centers, and A i Let f be the amplitude of the far-field scattered field at the i-th local scattering center, and f be the frequency of the incident electromagnetic wave. c To model the center frequency, α is the frequency dependence factor, φ is the radar azimuth angle, and γ is the center frequency. i φ i ′ represents a parameter to be estimated that has no physical meaning, φ 1i φ 2i W(φ) represents the minimum and maximum visible angles of the i-th local scattering center, respectively. 1i ,φ 2i ) is the window function, and k is the wave number. Let be the position vector of the i-th local scattering center. The radar line-of-sight vector represents the local scattering center.

[0058] The parameters of the far-field model of the local scattering center include: A i γ i φ i ′、φ 1iφ 2i α. Table 1 shows the input parameters of the far-field model of the local scattering center in the embodiments of the present invention. LSC1 to LSC4 represent the four local scattering centers in the embodiments of the present invention, respectively.

[0059] Far-field parameters of LSC LSC center coordinates <![CDATA[A i ]]> <![CDATA[γ i ]]> <![CDATA[φ′ i ]]> <![CDATA[φ 1i ]]> <![CDATA[φ 2i ]]> α LSC1 (0.1,-0.5，0) 0.11 0.99 3.64 -90 90 1 LSC2 (0.1,0.5，0) 0.10 0.35 6.23 -90 90 1 LSC3 (-0.1,0.5，0) 0.34 0.72 6.18 0 90 1 LSC4 (-0.1,-0.5，0) 0.37 0.74 3.53 -90 0 1

[0060] Table 1

[0061]

[0062] Where m represents the m-th distributed scattering center, Num_DSC represents the total number of distributed scattering centers, and B m Let L be the amplitude of the far-field scattered field of the m-th distributed scattering center. m Let φ′ be the length of the m-th distributed scattering center. m It is the angle at which the m-th distributed scattering center appears, and F(φ) is the Gaussian window function. Let m be the position vector of the m-th distributed scattering center. The radar line-of-sight vector represents the distributed scattering center.

[0063] The parameters of the distributed scattering center far-field model include: B m L, φ′ m α. Table 2 shows the parameters of the far-field model of the distributed scattering center in the embodiments of the present invention. DSC1 to DSC3 represent the three distributed scattering centers in the embodiments of the present invention, respectively.

[0064] DSC far-field parameters DSC center position coordinates <![CDATA[B m ]]> L <![CDATA[φ′ m ]]> α DSC1 (0.1,0，0) 17 1 0 1 DSC2 (0,0.5，0) 3 0.2 90 1 DSC3 (0,-0.5，0) 3 0.2 -90 1

[0065] Table 2

[0066] S2. Input radar parameters when the radar is in the near field; obtain the positional relationship between the local scattering center and the radar, and based on the positional relationship, correct the amplitude and phase of the far-field scattering field of the local scattering center to the corresponding amplitude and phase of the near-field scattering field, and obtain the near-field correction model of the local scattering center;

[0067] The radar parameters include: the radar's elevation and azimuth angles relative to the electrically large target, the straight-line distance between the radar and the center of the electrically large target, the radar antenna pattern data, and the radar frequency. For example... Figure 3 As shown, this embodiment uses a uniform antenna pattern generated by an ideal power source.

[0068] In this embodiment, the radar frequency is 5 GHz, and the single-station observation angle of the radar is θ = 90°. θ、 These are the elevation and azimuth angles of the single-station observation radar relative to the target center, respectively. The radar sampling points (the location of the observation radar) are 601 points, with VV polarization (this is a well-known industry term indicating that the polarization direction of the electromagnetic waves emitted and received by the radar is V (vertical) polarization). In this embodiment, when the observation radar is fixed at an elevation angle θ = 90° relative to the target, it moves upwards in azimuth to sample sequentially, specifically at the azimuth angle... A total of 601 points were sampled evenly across the area.

[0069] The amplitude of the near-field scattered field of the i-th local scattering center in step S2 is denoted as A. i_near Experimental tests revealed that the near-field GRCS of the LSC did not show a significant increase or decrease with the increase of the straight-line distance R between the radar and the center of the electrically large target. Instead, it oscillated irregularly within a small range, and the amplitude was slightly stronger than that in the far field. Therefore, the A correction was made. i_near for: Where G is the radar antenna gain, D is the maximum value of multiple one-dimensional lengths of an electrically large target in multiple dimensions, and λ is the radar wavelength.

[0070] Since the LSC's position is fixed at the geometric discontinuity of the target, it remains unchanged under both far-field and near-field conditions. Only in the near-field condition is the radar emitted wave transformed from a plane wave to a spherical wave considered. The phase correction of the near-field scattered field of the i-th local scattering center is: in The position vector of the local scattering center. This is the radar's position vector.

[0071] Local scattering center near-field correction model E LSC_near The expression is:

[0072]

[0073] Table 3 shows the near-field correction model E for the local scattering center in this embodiment. LSC_near The parameters are as follows:

[0074] LSC near-field parameters LSC center position coordinates <![CDATA[A i_near ]]> <![CDATA[γ i ]]> <![CDATA[φ′ i ]]> <![CDATA[φ 1i ]]> <![CDATA[φ 2i ]]> α R LSC1 (0.1,-0.5，0) 0.11 0.99 3.64 -90 90 1 5 LSC2 (0.1,0.5，0) 0.10 0.35 6.23 -90 90 1 5 LSC3 (-0.1,0.5，0) 0.34 0.72 6.18 0 90 1 5 LSC4 (-0.1,-0.5，0) 0.37 0.74 3.53 -90 0 1 5

[0075] Table 3

[0076] Substituting the parameters in Table 3 into formula (3) yields the near-field scattering field of the target's local scattering center. In this embodiment, under near-field conditions, R is set to 5m, and an ideal point source is used for the antenna; therefore, the term G(φ) can be ignored.

[0077] S3. Divide the distributed scattering center into L0 / λ segments; where L0 is the length of the electrically large target and λ is the radar wavelength. In this embodiment, each DSC is divided into 23 segments. Search for all segments where the distributed scattering center is observed by the radar at each radar line-of-sight angle. All segments constitute the observed area of ​​the distributed scattering center at that radar line-of-sight angle. Figure 3 In this context, the area where the antenna pattern overlaps with the target is the observed area of ​​the target (also known as the illuminated area).

[0078] If the angle between the radar line-of-sight vector (i.e., the direction of propagation of the electromagnetic wave emitted by the radar) and the normal vector at the midpoint of the segment is less than 1.25°, then the segment can be observed by the radar. The core of the calculation process for this angle is the dot product of the two vectors, which is a simple geometric calculation (existing technology).

[0079] S4. By using the step response function, the amplitude of the far-field scattering field of the distributed scattering center is corrected to the corresponding amplitude of the near-field scattering field.

[0080] Since the amplitude of DSC under near-field conditions is related to both the target reflective area and the radar range, this invention uses a step response function for correction. The step response function described in step S4 is:

[0081]

[0082] B m_near Let be the amplitude of the near-field scattered field of the m-th distributed scattering center; GRCS is the generalized radar cross section in the near field of the distributed scattering center. R is the straight-line distance between the radar and the center of the electrically large target;

[0083] Where, a = 0.992B′ m , B′ m For B m The value after taking the logarithm.

[0084] S5. Based on the positional relationship between the center point of the observed area corresponding to the distributed scattering center and the radar under the corresponding radar line-of-sight angle, the phase of the far-field scattering field of the distributed scattering center under the radar line-of-sight angle is corrected to the phase of the corresponding near-field scattering field; based on the amplitude, phase and number of observed segments of the near-field scattering field of the distributed scattering center under each radar line-of-sight angle, the near-field correction model of the distributed scattering center is obtained.

[0085] Step S5 includes:

[0086] S51. Calculate the near-field scattering field E of the m-th distributed scattering center under the full radar line-of-sight angle. DSC_near_m :

[0087]

[0088] Where p represents the p-th radar line-of-sight angle; Num_angle is the total number of radar line-of-sight angles; d L_m n is the length of the segment of the m-th distributed scattering center; p,m It is the number of segments observed by the radar at the p-th radar line-of-sight angle for the m-th distributed scattering center; It is the position vector of the center point of the observed area of ​​the m-th distributed scattering center under the p-th radar line-of-sight angle;

[0089] S52, Near-field Correction Model of Distributed Scattering Center E DSC_near for:

[0090]

[0091] In this embodiment, the near-field correction model E of the distributed scattering center DSC_near The parameters are shown in Table 4:

[0092] DSC near-field parameters Scattering center position coordinates <![CDATA[B m_near ]]> L <![CDATA[φ′ m ]]> α DSC1 (0.1,0，0) 499.13 1 0 1 DSC2 (0,0.5，0) 106.11 0.2 90 1 DSC3 (0,-0.5，0) 106.11 0.2 -90 1

[0093] Table 4

[0094] S6. The local scattering center near-field correction model and the distributed scattering center near-field correction model are summed to obtain the attribute scattering center near-field correction model. Based on the attribute scattering center near-field correction model, the near-field scattered echo of the electrically large target at the current radar position is obtained. The radar position is changed, and S2 to S6 are repeated to obtain the near-field scattered echo at different radar positions. Attribute Scattering Center Near-Field Correction Model E near The expression is: E near =E LSC_near +E DSC_near .

[0095] The accuracy of the near-field correction model for the scattering center of this invention can be demonstrated by comparing the results with those of the commercial electromagnetic simulation software FEKO. The RCS results of both models are as follows: Figure 4 As shown.

[0096] This invention corrects the far-field model of the attribute scattering center of electrically large targets in the near field. During missile-target encounters, it can quickly obtain a corrected near-field model of the attribute scattering center and generate near-field scattered echoes based on this model, avoiding time-consuming computation. The method of this invention has high accuracy and is suitable for rapid near-field echo simulation of targets. It can be applied to target tracking and identification by missile-borne radar and early warning by vehicle-borne radar.

[0097] It should be understood that the sequence number of each step in the above embodiments 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 this application.

[0098] 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 person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered 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 of echo generation based on an attribute scattering center near field correction model, an electrically large target having a plurality of localized scattering centers and a plurality of distributed scattering centers, characterized by, The method comprises steps of: S1, inputting parameters of a property scattering center far-field model of an electrically large target; S2, inputting radar parameters of the radar in a near field; obtaining a position relationship between the local scattering center and the radar, and correcting far-field scattering field amplitude and phase of the local scattering center to corresponding near-field scattering field amplitude and phase based on the position relationship to obtain a local scattering center near-field correction model; S3, dividing the distributed scattering center into multiple segments; searching all segments of the distributed scattering center observed by the radar under each radar line-of-sight angle, and the all segments constitute an observed region of the distributed scattering center under the radar line-of-sight angle; S4, correcting far-field scattering field amplitude of the distributed scattering center to corresponding near-field scattering field amplitude through a step response function; S5, correcting far-field scattering field phase of the distributed scattering center to corresponding near-field scattering field phase based on a position relationship between a center point of the corresponding observed region of the distributed scattering center and the radar under the corresponding radar line-of-sight angle; and obtaining a distributed scattering center near-field correction model based on amplitude and phase of the distributed scattering center near-field scattering field and the number of observed segments under each radar line-of-sight angle; S6, accumulating the local scattering center near-field correction model and the distributed scattering center near-field correction model to obtain a property scattering center near-field correction model; obtaining near-field scattering echoes of the electrically large target under a current radar position based on the property scattering center near-field correction model; changing the radar position, repeating S2 to S6, and obtaining near-field scattering echoes under different radar positions.

2. The echo generation method based on the attribute scattering center near-field correction model according to claim 1, characterized in that, The attribute scattering center far-field model includes: a local scattering center far-field model E LSC and a distributed scattering center far-field model E DSC ; where i denotes the i-th local scattering center, Num_LSC denotes the total number of local scattering centers, A i is the far-field scattering field amplitude of the i-th local scattering center, f is the incident electromagnetic wave frequency, f c is the modeling center frequency, a is the frequency-dependent factor, φ is the radar azimuth angle, γ i , φ′ i is the physically meaningless parameter to be estimated, φ 1i , φ 2i are the minimum and maximum visible angles of the i-th local scattering center, respectively, W(φ 1i ,φ 2i ) is the window function, k is the wave number, is the position vector of the i-th local scattering center, is the radar line-of-sight vector of the local scattering center; The input parameters of the local-type scatterer far-field model include: A i , γ i , φ′ i , φ 1i , φ 2i , α; where m represents the mth distribution type scattering center, Num_DSC represents the total number of distribution type scattering centers, B m is the amplitude of the far-field scattering field of the mth distribution type scattering center, L m is the length of the mth distribution type scattering center, φ′ m is the angle at which the mth distribution type scattering center appears, F(φ) is a Gaussian window function, is the position vector of the mth distribution type scattering center, is the radar line-of-sight vector of the distribution type scattering center; The input parameters of the distributed scattering center far-field model include: B m , L, φ' m , α.

3. The echo generation method based on the attribute scattering center near-field correction model of claim 1, wherein, The radar parameters include: a radar elevation angle and an azimuth angle relative to the electrically large target, a straight-line distance between the radar and a center of the electrically large target, radar antenna pattern data, and a radar frequency.

4. The echo generation method based on the attribute scattering center near-field correction model according to claim 2, characterized in that, The amplitude of the near-field scattering field of the i-th local type scattering center in step S2 is denoted as A i_near , wherein G is the radar antenna gain, D is the maximum value of the plurality of one-dimensional lengths of the electrically large-size target in a plurality of dimensions, and λ is the radar wavelength. The phase of the near field scattered field of the ith localized scattering center is wherein is the local a position vector of a scattering center, a position vector of a radar Local-type scatterer near-field correction model E LSC_near The expression is:

5. The echo generation method based on the attribute scattering center near-field correction model according to claim 1, characterized in that, In step S3, the distributed scattering center is divided into L0 / λ segments; wherein L0 is a length of the electrically large target, and λ is a radar wavelength.

6. The echo generation method based on the attribute scattering center near-field correction model according to claim 1, characterized in that, If an angle between a radar line-of-sight vector and a normal vector at a segment midpoint is less than 1.25°, the segment can be observed by the radar.

7. The echo generation method based on the attribute scattering center near-field correction model according to claim 4, characterized in that, In step S4, the step response function is: B m_near Amis the amplitude of the near-field scattering field for the mth distribution of scatterers; GRCS is the generalized radar cross section of the distribution of scatterers in the near field, R is the straight-line distance from the radar to the center of the electrically large target; where a = 0.992B' m , B' m is B m the values after taking the logarithm.

8. The echo generation method based on the attribute scattering center near-field correction model according to claim 7, characterized in that, Step S5 comprises: S51, calculate the near-field scattering field E of the mth distribution type scattering center under the full radar view angle DSC_near_m : where p represents the pth radar line-of-sight angle; Num_angle is the total number of radar line-of-sight angles; d L_m is the length of the segment of the mth distribution-type scattering center; n p,m is the number of segments of the mth distribution-type scattering center observed by the radar at the pth radar line-of-sight angle; is the center point position vector of the observed region of the mth distribution-type scattering center at the pth radar line-of-sight angle; S52, distributed scatterer near-field correction model E DSC_near is:

9. The echo generation method based on the attribute scattering center near-field correction model according to claim 8, characterized in that, The property scattering center near-field correction model E in step S6 near The expression is: E near = E LSC_near + E DSC_near .

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