A Simulation Method and System for Imaging Ellipsoidal Particle Targets Based on Electromagnetic Properties of Bistatic Fully Polarized Radar

Abstract

This application relates to the field of bistatic polarimetric radar technology, and particularly to a simulation method and system for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties. The method includes: setting radar parameters and ellipsoidal particle target parameters; calculating the far-field scattering coefficients of the ellipsoidal particles at different frequencies and target rotation angles under different polarization channels based on the radar parameters and ellipsoidal particle target parameters and utilizing the electromagnetic scattering characteristics of the ellipsoidal particles; simulating the received echoes of the corresponding bistatic fully polarimetric radar system based on the far-field scattering coefficients under different polarization channels, and extracting the scattering coefficients of noisy targets from the received echoes; and performing imaging processing on the scattering coefficients of each noisy target based on the bistatic inverse synthetic aperture radar (ISAR) turntable imaging principle to obtain a bistatic fully polarimetric radar image of the ellipsoidal particle target. This application simplifies the simulation process, fully considers the actual noise impact, and improves imaging efficiency.

Description

Technical Field

[0001] This application relates to the field of bistatic polarized radar technology, and in particular to a simulation method and system for bistatic fully polarized radar ellipsoidal particle target imaging based on electromagnetic properties. Background Technology

[0002] Bistatic fully polarimetric radar (BNP) is a radar system that uses the transmission and reception of orthogonally polarized waves to obtain the scattering characteristics of a target in a specific direction. By separating the transmission and reception, it introduces new degrees of freedom in the scattering matrix, which is beneficial for better identification of the target's three-dimensional information. In recent years, numerous bistatic fully polarimetric imaging systems have emerged and been used for Earth observation and terrain reconstruction, such as TanDEM-X and the LuTan-1 bistatic fully polarimetric synthetic aperture radar (SAR). However, current applications of bistatic fully polarimetric radar are mostly concentrated in small bistatic angle scenarios, primarily using SAR imaging interferometry through dual-satellite formations, lacking analysis and application of polarization mechanisms. For bistatic fully polarimetric radar image interpretation, the current mainstream method is imaging simulation combining scattering mechanisms and electromagnetic simulation; however, acquiring actual radar images still presents technical challenges and requires high costs.

[0003] Bistatic fully polarimetric radar imaging technology includes SAR imaging simulation and inverse SAR (ISAR) imaging simulation. The former typically constructs SAR images using scene target scattering mechanism models and projection mapping methods. It requires discretizing the target into scattering elements and can effectively image complex scenes, but for single-target scenarios, its computational load is high, resulting in insufficient simulation efficiency. The latter typically uses back-projection imaging methods, utilizing the scattering characteristics of the target at different azimuth angles to redistribute echo energy, thereby reconstructing the scattering center. Current research uses electromagnetic simulation methods such as physical optics and finite element methods to obtain the scattering coefficients of the target model at various frequencies and azimuth angles, and then combines them with back-projection imaging methods to reconstruct the target's ISAR image. However, this usually does not consider actual echo noise and still relies on methods such as mesh partitioning to solve the electromagnetic scattering model. For specific typical targets, such as ellipsoidal target particles, the polarized echo can be simulated directly using electromagnetic scattering characteristics, completing the entire simulation process efficiently and quickly.

[0004] Ellipsoidal particle targets, as one of the basic point targets, are well-suited for approximating shapes such as lines, elongated spheres, oblate spheroids, round spheres, and flat plates, and are widely used for modeling targets such as water droplets, leaves, and insects. Bistatic polarization analysis of ellipsoidal particles can effectively capture the scattering characteristics of directional targets. The bistatic scattering characteristics of ellipsoidal particles were already solved by Stevenson in 1953 using a power series method, yielding scattering results for ellipsoidal particles with specific orientations. When the particle's major axis is much smaller than the wavelength, using only the retained... This method yields a high-precision scattering matrix. Therefore, by combining the polarization rotation method with ellipsoidal particle scattering results, it is possible to obtain the polarization scattering matrix of an ellipsoidal particle target with arbitrary three-dimensional orientation at any frequency. The model itself is well-suited for ISAR imaging simulations and exhibits good computational efficiency.

[0005] Therefore, for ellipsoidal particle targets, by utilizing their electromagnetic scattering model and combining it with the bistatic polarimetric ISAR imaging method, it is possible to achieve bistatic fully polarimetric radar imaging simulation of such particle targets. This method simplifies the simulation process, fully considers the influence of actual noise, and greatly improves imaging efficiency, thus having significant application value in bistatic fully polarimetric radar image interpretation and parameter extraction. Summary of the Invention

[0006] The purpose of this application is to overcome the limitations of existing bistatic fully polarimetric radar image data acquisition, and to provide a simulation method and system for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties, so as to accurately simulate real bistatic fully polarimetric ISAR imaging and facilitate subsequent bistatic polarimetric image interpretation and parameter extraction.

[0007] To address the aforementioned technical problems, the technical solution provided in this application offers a simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties, comprising: Step 1: Set radar parameters and ellipsoidal particle target parameters; Step 2: Based on the radar parameters and ellipsoidal particle target parameters, and utilizing the electromagnetic scattering characteristics of ellipsoidal particles, calculate the far-field scattering coefficients of ellipsoidal particles in different polarization channels at each frequency point and target rotation angle. Step 3: Based on the far-field scattering coefficients under different polarization channels, simulate the received echoes of the corresponding bistatic fully polarized radar system, and extract the scattering coefficients of the noisy target from the received echoes; Step 4: Based on the imaging principle of bistatic inverse synthetic aperture radar (ISAR) turntable, the scattering coefficients of each noisy target are processed to obtain bistatic fully polarimetric radar images of ellipsoidal particle targets.

[0008] As an improvement to the above technical solution, step 1 includes: Set the center frequency of the radar ,bandwidth Frequency modulation Sampling rate and pulse repetition period ; Set the azimuth angle of the radar's transmitting antenna , Angle of incidence of transmitting antenna Radar receiving antenna azimuth angle and the angle of incidence of the receiving antenna ; Set the target rotation angle Frequency sampling number Azimuth sampling number and signal-to-noise ratio ; The relative permittivity of the target material Relative permeability of the target material ; Set the ellipsoidal particle in the body coordinate system Length of half shaft in the axial direction In the body coordinate system Length of half shaft in the axial direction and in the body coordinate system Length of half shaft in the axial direction ,in, ; Define the Euler angles for the ellipsoidal particles, where the Euler angles include the azimuth angle. Pitch angle and spin angle ; Define the spatial x-coordinate of the center position of the ellipsoidal particle. , spatial ordinate and spatial vertical coordinates .

[0009] As an improvement to the above technical solution, step 2 specifically includes: Step 2.1: Divide the frequency point sequence and target turning sequence :in, ; ; Among them, subscript Indicates the index of the frequency point sequence. Indicates the first Frequency point, subscript Indicates the index of the target corner sequence; Indicates the first One target corner; Step 2.2: Calculate the diagonal components of the polarization tensor and magnetic polarization tensor of the ellipsoidal particle in the three axes of the body coordinate system at each frequency point; Step 2.3: Calculate the scattering coefficients of the ellipsoidal particle caused by the electric field and the scattering coefficients caused by the magnetic field under different polarization channels; the polarization channels include: HH for emitting H-polarized waves and receiving H-polarized waves, VH for emitting V-polarized waves and receiving H-polarized waves, HV for emitting H-polarized waves and receiving V-polarized waves, and VV for emitting V-polarized waves and receiving V-polarized waves: where H represents horizontal and V represents vertical; Step 2.4: Calculate each frequency point Each target corner The polarization scattering coefficient of a lower ellipsoidal particle in different polarization channels.

[0010] As an improvement to the above technical solution, step 2.2 specifically includes: calculating the ellipsoidal particles in... Axial polarization tensor components and magnetic polarization tensor components ; Calculate the ellipsoidal particle in Axial polarization tensor components and magnetic polarization tensor components ; Calculate the ellipsoidal particle in Axial polarization tensor components and magnetic polarization tensor components ;in, ; ; Among them, subscript This indicates the axis index of the ellipsoidal particle in the body coordinate system. , For each ellipsoidal particle, the integral coefficients are given along the corresponding axis. For the first frequency points The wave number of electromagnetic waves; among which, ; in, express The corresponding integral variable; ; in, It is the speed of light in a vacuum.

[0011] As an improvement to the above technical solution, step 2.3 specifically includes: Calculate the far-field scattering coefficient of the ellipsoidal particle caused by the particle's electric field in the H-polarized wave emission and reception channels. The far-field scattering coefficient caused by the particle electric field in the channel for transmitting V-polarized waves and receiving H-polarized waves. The far-field scattering coefficient caused by the particle electric field in the channel for transmitting H-polarized waves and receiving V-polarized waves. and the far-field scattering coefficient caused by the particle electric field in the V-polarized wave transmission and reception channel. :

[0012] Calculate the far-field scattering coefficient of the ellipsoidal particle caused by the particle's magnetic field in the H-polarized wave emission and reception channels. The far-field scattering coefficient caused by the particle magnetic field in the channel for transmitting V-polarized waves and receiving H-polarized waves. The far-field scattering coefficient caused by the particle magnetic field in the channel for transmitting H-polarized waves and receiving V-polarized waves. and the far-field scattering coefficient caused by the particle magnetic field in the V-polarized wave transmission and reception channel. :

[0013] Among them, the radar first angle parameter satisfy Radar first angle parameters satisfy Thus, the target rotation angle is obtained. Scattering characteristics at that time.

[0014] As an improvement to the above technical solution, step 2.4 specifically includes: calculating each frequency point. Each target corner Below, the polarization scattering coefficient of an ellipsoidal particle in the H-polarized wave emission and reception channel. The polarization scattering coefficient of the transmitted V-polarized wave and received H-polarized wave in the channel. The polarization scattering coefficient of the transmitted H-polarized wave and received V-polarized wave in the channel. and the polarization scattering coefficient under the V-polarized wave transmission and reception channel. : ; ; ; ; in, The imaginary unit, Let the spatial position of the ellipsoidal particle target satisfy: ; in, The difference between the electromagnetic wave emission direction and the reception direction vector satisfies: .

[0015] As an improvement to the above technical solution, step 3 specifically includes: Step 3.1: Based on each frequency point Each target corner The polarization scattering coefficients of ellipsoidal particles under different polarization channels were used to simulate the radar system's received echoes under different polarization channels. : ; Among them, subscript Indicates the mode of receiving polarized waves. subscript Indicates the mode of transmitting polarized waves. ; Indicates the frequency points Perform an inverse Fourier transform on the data. Indicates the time intervals Perform a Fourier transform on the data. Indicates that at a sampling rate Sampling time, It is Gaussian white noise. For rectangular window functions: ; Step 3.2: System Echo Receiver Based on Simulation Extract the corresponding noisy target scattering coefficients. : ; When the number of time-domain sampling points of the signal is inconsistent with the number of frequency-domain sampling points of the target, Interpolate and resample to the same number of time-domain sampling points as the signal.

[0016] As an improvement to the above technical solution, step 4 specifically includes: Based on the imaging principle of a bistatic inverse synthetic aperture radar (ISAR) turntable, the scattering coefficients of noisy targets in each polarization channel are processed using imaging techniques, and the corresponding values ​​are calculated using the two-dimensional Simpson numerical integration method. Bistatic fully polarimetric radar images of ellipsoidal particle targets under polarization channels : ; in, Represents the x-coordinate in an ISAR image. Represents the vertical coordinate and frequency point in an ISAR image. These are discrete frequency points.

[0017] To achieve another objective of the present invention, the present invention also provides a dual-station fully polarimetric radar ellipsoidal particle target imaging simulation system based on electromagnetic properties, comprising: The parameter setting module is used to set radar parameters and ellipsoidal particle target parameters; The scattering coefficient calculation module is used to calculate the far-field scattering coefficient of the ellipsoidal particle under different polarization channels at each frequency point and at each target rotation angle, based on the radar parameters and the ellipsoidal particle target parameters and utilizing the electromagnetic scattering characteristics of the ellipsoidal particle. The extraction module is used to simulate the received echoes of the corresponding bistatic fully polarized radar system based on the far-field scattering coefficients under different polarization channels, and extract the scattering coefficients of noisy targets from the received echoes; and, The imaging processing module is used to perform imaging processing on the scattering coefficients of each noisy target based on the imaging principle of bistatic inverse synthetic aperture radar (ISAR) turntable, so as to obtain bistatic fully polarimetric radar images of ellipsoidal particle targets.

[0018] The advantage of this application lies in the fact that the method and system of this invention utilize the electromagnetic scattering model of ellipsoidal particle targets, combined with the bistatic polarimetric ISAR turntable imaging method, to quickly and efficiently achieve bistatic fully polarimetric radar imaging simulation of particle targets. This method simplifies the simulation process and fully considers the impact of actual noise, greatly improving imaging efficiency and providing important data references for bistatic fully polarimetric radar image interpretation and parameter extraction. Attached Figure Description

[0019] Figure 1 This is the overall flowchart of the simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties of the present invention; Figure 2 This is a flowchart illustrating the specific process of the bistatic fully polarimetric radar ellipsoidal particle target imaging simulation method based on electromagnetic properties according to the present invention. Figure 3 This is a schematic diagram of the ISAR turntable model of the bistatic fully polarimetric radar ellipsoidal particle target imaging simulation method based on electromagnetic properties according to the present invention. Figure 4 This is a bistatic HH polarization ISAR image corresponding to one embodiment; Figure 5 This is a bistationary HV polarimetric ISAR image corresponding to one embodiment; Figure 6 This is a bistatic VH polarization ISAR image corresponding to one embodiment; Figure 7 This is a corresponding bistatic VV polarization ISAR image in one embodiment. Detailed Implementation

[0020] The technical solutions provided in this application are further illustrated below with reference to the embodiments.

[0021] Example 1 This embodiment provides a simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties. It primarily addresses the problems of limited bistatic polarimetric radar image data, difficulty in acquisition, and limited consideration of polarization information in practical systems. The method includes: setting radar and target parameters; calculating the far-field scattering coefficients of the ellipsoidal particle target for different polarization waves at various azimuth angles and frequencies based on the electromagnetic properties of the ellipsoidal particles; simulating the radar system's received echo based on the scattering coefficients, considering factors such as signal noise, and extracting the scattering coefficients of noisy targets from the scattering coefficients; and acquiring simulated bistatic polarimetric radar images based on the bistatic ISAR turntable imaging principle. This embodiment can quickly and effectively acquire bistatic fully polarimetric radar images of ellipsoidal particles and can be applied to the field of bistatic radar target information interpretation.

[0022] The present invention will now be further described with reference to the accompanying drawings.

[0023] refer to Figure 1 Embodiment 1 of the present invention proposes a simulation method for imaging ellipsoidal particle targets based on electromagnetic properties using a bistatic fully polarimetric radar, comprising the following steps: Step 1) Set radar parameters and target parameters, including: radar center frequency ,bandwidth Frequency modulation Pulse repetition period Sampling rate ; Radar transmitting antenna azimuth angle , Angle of incidence of transmitting antenna Radar receiving antenna azimuth angle Receiver antenna incident angle ; Target rotation angle Frequency sampling number Azimuth sampling number Signal-to-noise ratio ; Relative permittivity of the target material Relative permeability of the target material ; ellipsoidal particles in body coordinate system Length of half shaft in the axial direction In the body coordinate system Length of half shaft in the axial direction In the body coordinate system Length of half shaft in the axial direction Generally there are ; Euler angles of ellipsoidal particles, including azimuth angles Pitch angle Spin angle ;as well as The spatial abscissa of the ellipsoidal particle center position , spatial ordinate Vertical coordinates in space ; Step 2) Based on the electromagnetic properties of ellipsoidal particles, calculate the far-field scattering coefficients of the ellipsoidal particle target for different polarizations at various azimuth angles and frequencies, including the far-field scattering coefficients of emitted and received H-polarized waves. Far-field scattering coefficient of transmitted V-polarized wave and received H-polarized wave Far-field scattering coefficient of emitted H-polarized wave and received V-polarized wave Far-field scattering coefficient of transmitted and received V-polarized waves ; Step 3) Considering factors such as signal noise, simulate the radar system's received echo based on the scattering coefficient. And extract the noisy target scattering coefficients from them, including the noisy target scattering coefficients of emitted and received H-polarized waves. The scattering coefficient of a noisy target that transmits V-polarized waves and receives H-polarized waves. The scattering coefficient of a noisy target that transmits H-polarized waves and receives V-polarized waves. The scattering coefficient of a noisy target when transmitting and receiving V-polarized waves. ; Step 4) Based on the imaging principle of the bistatic ISAR turntable, acquire simulated bistatic polarimetric radar images. .

[0024] refer to Figure 2 The steps in the method of the present invention will be further described below.

[0025] In step 1), the radar parameters and target parameters are set, including the radar center frequency. ,bandwidth Frequency modulation Pulse repetition period Sampling rate ; Radar transmitting antenna azimuth angle , Angle of incidence of transmitting antenna Radar receiving antenna azimuth angle Receiver antenna incident angle ; Target rotation angle Frequency sampling number Azimuth sampling number Signal-to-noise ratio ; Relative permittivity of the target material Relative permeability of the target material ; ellipsoidal particles in body coordinate system Length of half shaft in the axial direction In the body coordinate system Length of half shaft in the axial direction In the body coordinate system Length of half shaft in the axial direction Generally there are ; Euler angles of ellipsoidal particles, including azimuth angles Pitch angle Spin angle ;as well as The spatial abscissa of the ellipsoidal particle center position , spatial ordinate Vertical coordinates in space .

[0026] In one embodiment, we selected simulation experiment parameters as shown in Table 1.

[0027] Table 1 Simulation parameters for the example:

[0028] Based on the radar and target parameters input in step 1), in step 2), we further perform the following: Step 2) Based on the electromagnetic properties of ellipsoidal particles, calculate the far-field scattering coefficients of the ellipsoidal particle target for different polarizations at various azimuth angles and frequencies, including the far-field scattering coefficients of emitted and received H-polarized waves. Far-field scattering coefficient of transmitted V-polarized wave and received H-polarized wave Far-field scattering coefficient of emitted H-polarized wave and received V-polarized wave Far-field scattering coefficient of transmitted and received V-polarized waves Step 2 specifically includes: Step 2.1: Divide the frequency point sequence and target turning sequence :

[0029] in, This is a sequence index, representing the index of the current frequency point or turning point.

[0030] Step 2.2: Calculate the diagonal elements of the ellipsoidal particle electromagnetic polarization tensor at each frequency point, including the ellipsoidal particle... Axial polarization tensor components and magnetic polarization tensor components ellipsoidal particles Axial polarization tensor components and magnetic polarization tensor components ellipsoidal particles Axial polarization tensor components and magnetic polarization tensor components :

[0031] Among them, subscript , These represent the three semi-axial directions of the ellipsoidal particle, where... For ellipsoidal particles Integral on the axis, For ellipsoidal particles Integral on the axis, For ellipsoidal particles Integral on the axis, express The corresponding integral variable, For the first frequency points The wave number of the electromagnetic wave satisfies:

[0032] here, It is the speed of light in a vacuum.

[0033] Step 2.3: Calculate the scattering coefficients of the ellipsoidal particles caused by the electric and magnetic fields respectively:

[0034]

[0035] in, The far-field scattering coefficient of H-polarized waves emitted and received by the particle electric field. The far-field scattering coefficient of the emitted V-polarized wave and received H-polarized wave, caused by the particle's electric field. The far-field scattering coefficient of the emitted H-polarized wave and received V-polarized wave, caused by the particle's electric field. The far-field scattering coefficient of the V-polarized wave, caused by the particle's electric field, is used to transmit and receive V-polarized waves. The far-field scattering coefficient of H-polarized waves emitted and received by the particle magnetic field. The far-field scattering coefficient of the emitted V-polarized wave and received H-polarized wave caused by the particle's magnetic field. The far-field scattering coefficient of the emitted H-polarized wave and received V-polarized wave caused by the particle's magnetic field. The far-field scattering coefficient of the V-polarized wave, caused by the particle magnetic field, is received by transmitting and receiving V-polarized waves.

[0036] In addition, the radar's first angle parameters and radar first angle parameters ,satisfy:

[0037] Thus, the target rotation angle is obtained. Scattering characteristics at that time.

[0038] Step 2.4: Calculate each frequency point Each corner Polarization scattering coefficient of lower ellipsoidal particles , , , :

[0039] in, The imaginary unit, The spatial position of the ellipsoidal particle target. The difference between the electromagnetic wave emission direction and the reception direction vector satisfies the following:

[0040] Step 3) Considering factors such as signal noise, simulate the radar system's received echo based on the scattering coefficient. And extract the noisy target scattering coefficients from them, including the noisy target scattering coefficients of emitted and received H-polarized waves. The scattering coefficient of a noisy target that transmits V-polarized waves and receives H-polarized waves. The scattering coefficient of a noisy target that transmits H-polarized waves and receives V-polarized waves. The scattering coefficient of a noisy target when transmitting and receiving V-polarized waves. Step 3 specifically includes: Step 3.1: Based on the polarization scattering coefficients of ellipsoidal particles at various frequencies and azimuth angles, simulate the received echoes of radar systems with different polarization channels. :

[0041] Among them, subscript or Represents horizontal or vertical polarization. Indicates the frequency points Perform an inverse Fourier transform on the data. Indicates the time intervals Perform a Fourier transform on the data. Indicates that at a sampling rate Sampling time, It is Gaussian white noise. For rectangular window functions:

[0042] The sampling time here is considered to be 2µs.

[0043] Step 3.2: Extract the scattering coefficients of the noisy target based on the simulated system received echo. :

[0044] The number of time-domain sampling points for the signal and the number of frequency-domain sampling points for the target are usually different, requiring... Interpolate and resample to the same number of time-domain sampling points as the signal.

[0045] Step 4), as Figure 3 As shown, based on the imaging principle of the bistatic ISAR turntable, simulated bistatic polarimetric radar images are obtained. :

[0046] in, Represents the x-coordinate in an ISAR image. Representing the ordinate in the ISAR image, the image of each polarization channel is calculated using the two-dimensional Simpson numerical integration method. Due to frequency Since the frequency points are discrete, the discrete integral needs to be calculated using the two-dimensional Simpson integral method. This method utilizes the scattering of the entire target in space, focusing it onto the plane at z=0 for solution, thus not involving z. By taking arbitrary values ​​for (x, y), the scattering at the (x, y) coordinates in the ISAR image can be calculated.

[0047] Figures 4-7 The image shown is the HH, HV, VH, VV polarization channel image of the bistatic radar for ellipsoidal particles obtained using this electromagnetic property model in the embodiment.

[0048] The results show that, under the set imaging parameters, the image distribution of each polarization channel of the ellipsoidal particle target is basically consistent, but the amplitudes are different. For the particle target, its size is much smaller than the resolution, and theoretically, the imaging result should be a point target. However, the actual simulated image does not present the ideal point shape, but rather an ellipse. This phenomenon is due to the mismatch between the imaging grid resolution and the effective resolution of the system. In the simulation, to ensure imaging details, the sampling interval of the imaging grid was set smaller than the effective resolution of the actual system. When the main lobe of the echo signal is discretely sampled, the energy is distributed to multiple adjacent pixels. Furthermore, since the current sampling is done through a rectangular window, many sidelobes are generated. These can be suppressed by adding a Hamming window to improve the results. In practical applications, the amplitude and phase characteristics of each polarization channel can be extracted to analyze the spatial characteristics of the point target, such as the polarization orientation angle parameter, to reconstruct the target's three-dimensional orientation.

[0049] Example 2 Embodiment 2 of the present invention proposes a dual-station fully polarimetric radar ellipsoidal particle target imaging simulation system based on electromagnetic properties, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the dual-station fully polarimetric radar ellipsoidal particle target imaging simulation method based on electromagnetic properties provided in Embodiment 1, including: The parameter setting module is used to set radar parameters and ellipsoidal particle target parameters; The scattering coefficient calculation module is used to calculate the far-field scattering coefficient of the ellipsoidal particle under different polarization channels at each frequency point and at each target rotation angle, based on the radar parameters and the ellipsoidal particle target parameters and utilizing the electromagnetic scattering characteristics of the ellipsoidal particle. The extraction module is used to simulate the received echoes of the corresponding bistatic fully polarized radar system based on the far-field scattering coefficients under different polarization channels, and extract the scattering coefficients of noisy targets from the received echoes; and, The imaging processing module is used to perform imaging processing on the scattering coefficients of each noisy target based on the imaging principle of bistatic inverse synthetic aperture radar (ISAR) turntable, so as to obtain bistatic fully polarimetric radar images of ellipsoidal particle targets.

[0050] In summary, the bistatic fully polarimetric radar ellipsoidal particle target imaging simulation method and system provided by this invention simulates the scattered echoes from various azimuth angles based on the general electromagnetic scattering calculation method for ellipsoidal particles. By incorporating error factors such as noise, it reconstructs the polarization characteristics of the scattering centers of each polarization channel, generating bistatic fully polarimetric ISAR images. This method and system can effectively simulate the bistatic fully polarimetric ISAR imaging process of ellipsoidal particles, and the results conform to the actual image characteristics, verifying the effectiveness of the simulation method and system proposed in this invention. It reduces computational load, comprehensively covers system errors, and improves simulation efficiency.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties, comprising: Step 1: Set radar parameters and ellipsoidal particle target parameters; Step 2: Based on the radar parameters and ellipsoidal particle target parameters, and utilizing the electromagnetic scattering characteristics of ellipsoidal particles, calculate the far-field scattering coefficients of ellipsoidal particles in different polarization channels at each frequency point and target rotation angle. Step 3: Based on the far-field scattering coefficients under different polarization channels, simulate the received echoes of the corresponding bistatic fully polarized radar system, and extract the scattering coefficients of the noisy target from the received echoes; Step 4: Based on the imaging principle of bistatic inverse synthetic aperture radar (ISAR) turntable, the scattering coefficients of each noisy target are processed to obtain bistatic fully polarimetric radar images of ellipsoidal particle targets.

2. The simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties according to claim 1, characterized in that, Step 1 includes: Set the center frequency of the radar ,bandwidth Frequency modulation Sampling rate and pulse repetition period ; Set the azimuth angle of the radar's transmitting antenna , Angle of incidence of transmitting antenna Radar receiving antenna azimuth angle and the angle of incidence of the receiving antenna ; Set the target rotation angle Frequency sampling number Azimuth sampling number and signal-to-noise ratio ; The relative permittivity of the target material Relative permeability of the target material ; Set the ellipsoidal particle in the body coordinate system Length of half shaft in the axial direction In the body coordinate system Length of half shaft in the axial direction and in the body coordinate system Length of half shaft in the axial direction ,in, ; Define the Euler angles for the ellipsoidal particles, where the Euler angles include the azimuth angle. Pitch angle and spin angle ; Define the spatial x-coordinate of the center position of the ellipsoidal particle. , spatial ordinate and spatial vertical coordinates .

3. The simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties according to claim 2, characterized in that, Step 2 specifically includes: Step 2.1: Divide the frequency point sequence and target turning sequence :in, ； ； Among them, subscript Indicates the index of the frequency point sequence. Indicates the first Frequency point, subscript Indicates the index of the target corner sequence; Indicates the first One target corner; Step 2.2: Calculate the diagonal components of the polarization tensor and magnetic polarization tensor of the ellipsoidal particle in the three axes of the body coordinate system at each frequency point; Step 2.3: Calculate the scattering coefficients of the ellipsoidal particle caused by the electric field and the scattering coefficients caused by the magnetic field under different polarization channels; the polarization channels include: HH for emitting H-polarized waves and receiving H-polarized waves, VH for emitting V-polarized waves and receiving H-polarized waves, HV for emitting H-polarized waves and receiving V-polarized waves, and VV for emitting V-polarized waves and receiving V-polarized waves: where H represents horizontal and V represents vertical; Step 2.4: Calculate each frequency point Each target corner The polarization scattering coefficient of a lower ellipsoidal particle in different polarization channels.

4. The simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties according to claim 3, characterized in that, Step 2.2 specifically includes: calculating the ellipsoidal particles in... axial polarization tensor components and magnetic polarization tensor components ; Calculate the ellipsoidal particle in axial polarization tensor components and magnetic polarization tensor components ; Calculate the ellipsoidal particle in Axial polarization tensor components and magnetic polarization tensor components ;in, ； ； Among them, subscript This indicates the axis index of the ellipsoidal particle in the body coordinate system. , For each ellipsoidal particle, the integral coefficients are given along the corresponding axis. For the first frequency points The wave number of electromagnetic waves; among which, ； in, express The corresponding integral variable; ； in, It is the speed of light in a vacuum.

5. The simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties according to claim 4, characterized in that, Step 2.3 specifically includes: Calculate the far-field scattering coefficient of the ellipsoidal particle caused by the particle's electric field in the H-polarized wave emission and reception channels. The far-field scattering coefficient caused by the particle electric field in the channel for transmitting V-polarized waves and receiving H-polarized waves. The far-field scattering coefficient caused by the particle electric field in the channel for transmitting H-polarized waves and receiving V-polarized waves. and the far-field scattering coefficient caused by the particle electric field in the V-polarized wave transmission and reception channel. : Calculate the far-field scattering coefficient of the ellipsoidal particle caused by the particle's magnetic field in the H-polarized wave emission and reception channels. The far-field scattering coefficient caused by the particle magnetic field in the channel for transmitting V-polarized waves and receiving H-polarized waves. The far-field scattering coefficient caused by the particle magnetic field in the channel for transmitting H-polarized waves and receiving V-polarized waves. and the far-field scattering coefficient caused by the particle magnetic field in the V-polarized wave transmission and reception channel. : Among them, the radar first angle parameter satisfy Radar first angle parameters satisfy Thus, the target rotation angle is obtained. Scattering characteristics at that time.

6. The simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties according to claim 5, characterized in that, Step 2.4 specifically includes: calculating each frequency point. Each target corner Below, the polarization scattering coefficient of an ellipsoidal particle in the H-polarized wave emission and reception channel. The polarization scattering coefficient of the transmitted V-polarized wave and received H-polarized wave in the channel. The polarization scattering coefficient of the transmitted H-polarized wave and received V-polarized wave in the channel. and the polarization scattering coefficient under the V-polarized wave transmission and reception channel. : ； ； ； ； in, The imaginary unit, Let the spatial position of the ellipsoidal particle target satisfy: ； in, The difference between the electromagnetic wave emission direction and the reception direction vector satisfies: 。 7. The simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties according to claim 6, characterized in that, Step 3 specifically includes: Step 3.1: Based on each frequency point Each target corner The polarization scattering coefficients of ellipsoidal particles under different polarization channels were used to simulate the radar system's received echoes under different polarization channels. : ； Among them, subscript Indicates the mode of receiving polarized waves. subscript Indicates the mode of transmitting polarized waves. ; Indicates the frequency points Perform an inverse Fourier transform on the data. Indicates the time intervals Perform a Fourier transform on the data. Indicates that at a sampling rate Sampling time, It is Gaussian white noise. For rectangular window functions: ； Step 3.2: System Echo Receiver Based on Simulation Extract the corresponding noisy target scattering coefficients. : ； When the number of time-domain sampling points of the signal is inconsistent with the number of frequency-domain sampling points of the target, Interpolate and resample to the same number of time-domain sampling points as the signal.

8. The simulation method for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties according to claim 7, characterized in that, Step 4 specifically includes: Based on the imaging principle of a bistatic inverse synthetic aperture radar (ISAR) turntable, the scattering coefficients of noisy targets in each polarization channel are processed using imaging techniques, and the corresponding values ​​are calculated using the two-dimensional Simpson numerical integration method. Bistatic fully polarimetric radar images of ellipsoidal particle targets under polarization channels : ； in, Represents the x-coordinate in an ISAR image. Represents the vertical coordinate and frequency point in an ISAR image. These are discrete frequency points.

9. A dual-station fully polarimetric radar ellipsoidal particle target imaging simulation system based on electromagnetic properties, characterized in that, include: The parameter setting module is used to set radar parameters and ellipsoidal particle target parameters; The scattering coefficient calculation module is used to calculate the far-field scattering coefficient of the ellipsoidal particle under different polarization channels at each frequency point and at each target rotation angle, based on the radar parameters and the ellipsoidal particle target parameters and utilizing the electromagnetic scattering characteristics of the ellipsoidal particle. The extraction module is used to simulate the received echoes of the corresponding bistatic fully polarimetric radar system based on the far-field scattering coefficients under the different polarization channels, and extract the scattering coefficients of noisy targets from the received echoes. and, The imaging processing module is used to perform imaging processing on the scattering coefficients of each noisy target based on the imaging principle of bistatic inverse synthetic aperture radar (ISAR) turntable, so as to obtain bistatic fully polarimetric radar images of ellipsoidal particle targets.

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