CN-118642122-B - Missile-borne radar terahertz rapid imaging method based on high-frequency electromagnetic scattering algorithm

CN118642122BCN 118642122 BCN118642122 BCN 118642122BCN-118642122-B

Abstract

The invention discloses a high-frequency electromagnetic scattering algorithm-based missile-borne radar terahertz rapid imaging method which comprises the steps of dividing a real imaging scene containing a background and a target into a plurality of grid cells, determining the grid cells within the irradiation range of a transmitting antenna beam from the grid cells, determining the grid cells which can be irradiated by the transmitting antenna beam from the grid cells within the irradiation range of the transmitting antenna beam, calculating the radar image intensity of each irradiated grid cell and the coordinates of a corresponding point of each irradiated grid cell in a two-dimensional image of the real imaging scene, and obtaining the two-dimensional image of the real imaging scene according to the radar image intensity of the irradiated grid cells and the coordinates of the corresponding point in the two-dimensional image of the real imaging scene. The invention can greatly improve the simulation speed while ensuring the image precision.

Inventors

GUO GUANGBIN
WANG RUI
YANG XUN

Assignees

西安电子科技大学

Dates

Publication Date: 20260512
Application Date: 20240529

Claims (9)

1. A missile-borne radar terahertz rapid imaging method based on a high-frequency electromagnetic scattering algorithm is characterized by comprising the following steps of: dividing a real imaging scene containing a background and a target into a plurality of grid surface elements; Determining a grid cell within an irradiation range of a transmitting antenna beam from the plurality of grid cells; determining grid cells which can be irradiated by the transmitting antenna beam from the grid cells which are in the irradiation range of the transmitting antenna beam; Calculating the radar image intensity of each irradiated grid cell and the coordinates of the corresponding point of each irradiated grid cell in the two-dimensional image of the real imaging scene; Obtaining a two-dimensional image of the real imaging scene according to the radar image intensity of the irradiated grid surface element and the coordinates of the corresponding point in the two-dimensional image of the real imaging scene; Wherein the expression of radar image intensity of each irradiated mesh bin is as follows: ; ; ; ; Wherein, the , For the frequency of the incident wave, Is the wave number of the electromagnetic wave, As the direction of incidence of the light, For the distance of the center of the illuminated grid cell to the receiving antenna, And The magnitude vectors of the electric and magnetic fields respectively, And The reflection coefficients of the target for TE wave and TM wave respectively, And The direction vectors of TE and TM waves respectively, And The permittivity and the permeability are respectively given, For the wave number corresponding to the radar center frequency, Is the incident direction corresponding to the central angle when the radar scans the angle, In order to be able to achieve an angular velocity, In order to achieve an angular scanning time, In units of imaginary numbers, Representing the number of bounces of an initial incident ray incident on the irradiated mesh bin, wherein when the irradiated mesh bin is a mesh bin directly irradiated by a transmit antenna beam 1, When the irradiated grid cell is a grid cell irradiated by a reflected transmitting antenna beam Is more than or equal to 2 and is not less than, First to initial incident ray The direction of the secondary bounce is set, The first ray on the bounce path for the initial incident ray The normal vector of the cells of the grid, For the center coordinates of the illuminated mesh bin, For the area of the illuminated mesh bin, Corresponding points in the two-dimensional image of the real imaging scene for the illuminated grid elements The coordinates of the two points of the coordinate system, Corresponding points in the two-dimensional image of the real imaging scene for the illuminated grid elements The coordinates of the two points of the coordinate system, In Cartesian coordinate system In the direction of the axis of the shaft, For the normal vector of the illuminated mesh bin, For the width of the radar scan angle, Is that Is set at the maximum value of (c), Is that Is set to be a minimum value of (c), For the scattering direction corresponding to the center of each scan angle of the radar, Passing through for initial incident radiation incident on the irradiated grid cell Total bouncing path after secondary bouncing.
2. The method for rapid imaging of a missile-borne radar terahertz based on a high-frequency electromagnetic scattering algorithm according to claim 1, wherein the determining, from the plurality of grid cells, the grid cells within an irradiation range of a transmitting antenna beam includes: for each grid cell of the plurality of grid cells, taking a connection line between the center of the grid cell and the position of the transmitting antenna as an initial incident ray of the grid cell; calculating an included angle between an initial incident ray of the grid surface element and the beam direction of the transmitting antenna; and when the included angle is smaller than half of the beam width, indicating that the grid surface element is in the irradiation range of the transmitting antenna beam, otherwise, indicating that the grid surface element is not in the irradiation range of the transmitting antenna beam.
3. The method for rapidly imaging a terahertz of a missile-borne radar based on a high-frequency electromagnetic scattering algorithm according to claim 1, wherein each grid element corresponds to an initial incident ray, the initial incident ray is a line between the center of the grid element and the position of a transmitting antenna, and the determining the grid element which can be irradiated by the transmitting antenna beam from the grid elements within the irradiation range of the transmitting antenna beam includes: determining grid surface elements of which the corresponding initial incident rays are not shielded by a target or a background in the real imaging scene from the grid surface elements in the irradiation range of the transmitting antenna beam, and obtaining grid surface elements directly irradiated by the transmitting antenna beam; determining the grid cells which are irradiated by the reflected transmitting antenna beams from the grid cells which are in the irradiation range of the transmitting antenna beams, wherein the initial incident rays corresponding to the grid cells which are directly irradiated by the transmitting antenna beams are irradiated by the grid cells after bouncing; And taking the grid cells directly irradiated by the transmitting antenna beam and the grid cells irradiated by the reflected transmitting antenna beam as the grid cells irradiated by the transmitting antenna beam.
4. A method for rapid imaging of a missile-borne radar terahertz based on a high-frequency electromagnetic scattering algorithm as claimed in claim 3, wherein the step of calculating the radar image intensity of each irradiated grid cell includes: For each irradiated mesh bin, determining a scatter field of the irradiated mesh bin; the radar image intensity of the irradiated mesh bin is determined by inverse two-dimensional fourier transform based on the scattered field of the irradiated mesh bin, the distance from the center of the irradiated mesh bin to the receiving antenna, and the wave number of the electromagnetic wave.
5. The method for rapidly imaging a terahertz wave of a missile-borne radar based on a high-frequency electromagnetic scattering algorithm according to claim 4, wherein when the wave emitted by the transmitting antenna is a terahertz wave, 、 The expressions of (2) are respectively: ; ; Wherein, the For the angle between the incident wave and the incident surface, For the reflection coefficient of the TE wave for a smooth plane, Is the reflection coefficient of the smooth plane to the TM wave, For the wavelength of the incident wave, Is the roughness of the incident surface.
6. The method for rapidly imaging the terahertz of the missile-borne radar based on the high-frequency electromagnetic scattering algorithm according to claim 4, wherein, ; ; Wherein, the = , Passing through for initial incident radiation incident on the irradiated grid cell Total bouncing path after secondary bouncing.
7. The high-frequency electromagnetic scattering algorithm-based missile-borne radar terahertz rapid imaging method as claimed in claim 4 or 6, wherein the steps of Coordinates and the The expressions of the coordinates are respectively: ; 。
8. The method for terahertz rapid imaging of missile-borne radar based on high-frequency electromagnetic scattering algorithm according to claim 3, wherein the determining the grid cell to which the initial incident ray corresponding to the grid cell irradiated by at least one directly emitted antenna beam is incident after bouncing from the grid cells within the irradiation range of the emitted antenna beam to obtain the grid cell irradiated by the reflected emitted antenna beam includes: Sequentially carrying out ray tracing intersection test on initial incident rays corresponding to grid cells irradiated by the directly emitted antenna beams in the real imaging scene by adopting a ray tracing method, and screening out grid cells irradiated by at least one initial incident ray corresponding to the grid cells irradiated by the directly emitted antenna beams after bouncing from the grid cells in the irradiation range of the emitted antenna beams according to the ray tracing intersection test result; and taking the screened grid cells as the grid cells irradiated by the reflected transmitting antenna beams.
9. The method for rapid imaging of a missile-borne radar terahertz based on a high-frequency electromagnetic scattering algorithm according to claim 1, wherein when the two-dimensional image of the real imaging scene is obtained from the radar image intensity of the irradiated grid cells and the coordinates of the corresponding points in the two-dimensional image of the real imaging scene, the method further includes: When coordinates of corresponding points of two or more irradiated grid cells in the two-dimensional image of the real imaging scene are the same, accumulating radar image intensities of the two or more irradiated grid cells, and taking the accumulated radar image intensity as the radar image intensity of the points.

Description

Missile-borne radar terahertz rapid imaging method based on high-frequency electromagnetic scattering algorithm Technical Field The invention belongs to the technical field of terahertz imaging, and particularly relates to a missile-borne radar terahertz rapid imaging method based on a high-frequency electromagnetic scattering algorithm. Background In recent years, terahertz is widely applied to various fields of medicine, communication, passenger flow security inspection, farm product detection, national defense and military and the like due to remarkable and unique properties such as strong penetrability, strong anti-interference force, narrow beam, high carrier frequency and the like. It is worth mentioning that the combination of the SAR imaging and SAR imaging breaks through a plurality of limitations and bottlenecks, and has larger research value and wider application prospect. Compared with the traditional microwave imaging, one of the advantages of terahertz imaging is that radar images with higher resolution can be obtained, however, higher frequency band and resolution face greater challenges for electromagnetic scattering simulation technology, for imaging simulation of actual oversized scenes, the process of generating scattering echoes and imaging by adopting the traditional simulation SAR detection process is very time-consuming, and especially in the terahertz frequency band, the calculation amount of the radar images can be further increased by the higher resolution, and the data production requirements under large samples are difficult to meet. At present, two-dimensional Synthetic Aperture Radar (SAR) image simulation based on a high-frequency scattering algorithm is mainly used for simulating a real SAR detection process, a scattered echo at each receiving position in a flight track is simulated by adopting the high-frequency scattering algorithm according to an SAR 'stop-go' mode, a direction-distance echo matrix is formed, and a final SAR image is obtained by utilizing an SAR imaging processing algorithm. However, the current SAR imaging simulation generally adopts a technology of simulating an SAR detection process and simulating a scattered echo and then imaging, so that the process of acquiring a two-dimensional scattered echo matrix of the actual ultra-large scene is very time-consuming, and particularly in a terahertz frequency band, the calculated amount is further increased by a higher resolution, and the data production requirement under a large sample is difficult to meet. That is, the existing SAR imaging simulation method has high simulation modeling complexity and low efficiency of the missile-borne radar imaging under a high-resolution large scene, and cannot meet the requirement of rapid data production under a large sample size. Disclosure of Invention In order to solve the problems in the prior art, the invention provides a missile-borne radar terahertz rapid imaging method based on a high-frequency electromagnetic scattering algorithm. The technical problems to be solved by the invention are realized by the following technical scheme: The invention provides a missile-borne radar terahertz rapid imaging method based on a high-frequency electromagnetic scattering algorithm, which comprises the following steps of: dividing a real imaging scene containing a background and a target into a plurality of grid surface elements; Determining a grid cell within an irradiation range of a transmitting antenna beam from the plurality of grid cells; determining grid cells which can be irradiated by the transmitting antenna beam from the grid cells which are in the irradiation range of the transmitting antenna beam; Calculating the radar image intensity of each irradiated grid cell and the coordinates of the corresponding point of each irradiated grid cell in the two-dimensional image of the real imaging scene; And obtaining the two-dimensional image of the real imaging scene according to the radar image intensity of the irradiated grid cells and the coordinates of the corresponding points in the two-dimensional image of the real imaging scene. In some embodiments, the determining, from the plurality of grid cells, a grid cell that is within an illumination range of a transmit antenna beam includes: for each grid cell of the plurality of grid cells, taking a connection line between the center of the grid cell and the position of the transmitting antenna as an initial incident ray of the grid cell; calculating an included angle between an initial incident ray of the grid surface element and the beam direction of the transmitting antenna; and when the included angle is smaller than half of the beam width, indicating that the grid surface element is in the irradiation range of the transmitting antenna beam, otherwise, indicating that the grid surface element is not in the irradiation range of the transmitting antenna beam. In some embodiments, each grid cell corresponds to an initial incid