Near-field circumferential SAR rapid three-dimensional imaging method

A technology of three-dimensional imaging and two-dimensional imaging, which is applied in the field of three-dimensional imaging to achieve precise imaging, improve computing speed, and solve the effects of rotation angle restrictions

Active Publication Date: 2018-11-23
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AI-Extracted Technical Summary

Problems solved by technology

[0004] In order to overcome the limitation of the existing algorithm on the rotation angle and the lack of three-dimen...
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The invention provides a near-field circumferential SAR rapid three-dimensional imaging method, and relates to the field of microwave imaging. Firstly, the target is converted into the polar coordinate format to obtain the target echo, and then analysis is performed by using the wave spectrum theory and the two-dimensional imaging result of the target is obtained by using the mode of angle domainconvolution calculation and frequency domain integration operation. The target scattering characteristic functions of different altitude surfaces are accordingly obtained through different altitude values and the information of different altitude surfaces is superposed so as to obtain the three-dimensional imaging result. The idea of combining Green's function decomposition and tomography is utilized to improve the operation speed of near-field circumferential imaging and also improve the image resolution, the target echo is precisely focused by using the Green's function decomposition technology so that the limitation of the rotation angle by the focusing convolution integration method is effectively solved, and the three-dimensional imaging result is obtained by using the idea of tomography. The target echo data can be precisely imaged effectively through the simulation result.

Application Domain

Radio wave reradiation/reflection

Technology Topic

PhysicsTomography +8


  • Near-field circumferential SAR rapid three-dimensional imaging method
  • Near-field circumferential SAR rapid three-dimensional imaging method
  • Near-field circumferential SAR rapid three-dimensional imaging method


  • Experimental program(1)

Example Embodiment

[0057] The example is as follows:
[0058] Step 1: Obtain the echo data of two-dimensional imaging: Firstly, ignore the influence of height on imaging and reduce the target dimension from three-dimensional to two-dimensional. It is assumed that all points on the height in the scene are located on the ground plane. The radar transmits a chirp signal p(t) to the target, and the target reflection function is set to f(x,y). According to the circular SAR geometric imaging model, the target echo signal s(t,θ), s(t,θ) can be expressed for:
[0060] Where c represents the speed of light, R(θ) represents the distance between the radar and the target under the angle θ when the target rotates with the radar, R represents the horizontal distance between the radar and the center of the turntable, which is equivalent to the radius of movement of the radar, and H represents the vertical height between the radar and the ground.
[0061] In this embodiment, the center frequency is S-band, the radar height is 5 meters, the horizontal distance from the radar to the center of the turntable is 5 meters, the downward viewing angle is 45°, the radar rotation angle is 360°, and the angular sampling interval is 0.5°. Calculated by far and near field formula Among them, D is the target size and λ is the wavelength, so the model belongs to the near-field model.
[0062] Step 2: Echo signal preprocessing: convert the target from Cartesian coordinate system to polar coordinate system That, at this time R(θ) can be expressed as:
[0064] Perform Fourier transform on the echo signal in fast time and ignore the influence of amplitude to obtain the echo signal S(f, θ) in the range frequency-azimuth angle domain. The expression is:
[0066] Represents the near-field oblique plane Green's function, and its expression is: k represents the size of the wave number, k=2πf/c.
[0067] Step 3: Two-dimensional imaging solution, the specific steps are: after analyzing S(f,θ), the two-dimensional reflection function of the target can be known Is obtained by the two-dimensional inverse Fourier transform of S(f,θ), and its expression is:
[0069] Approximately express R(θ),
[0071] Where θ z Indicates the overhead angle of the antenna, θ z =arctan(H/R), the target reflection function can be expressed as:
[0073] Let k r =kcosθ z ,k z =ksinθ z , Rewrite as:
[0075] The internal integral of the angle can be expressed as
[0077] Keep on To simplify:
[0079] At this time, the two-dimensional reflection function of the target in polar coordinates is solved, and the Carrying out the Cartesian coordinate transformation, the target two-dimensional reflection function f(x,y) in the Cartesian coordinate system is obtained.
[0080] Step 4: Three-dimensional imaging solution: Discretize the radar height, and the corresponding discrete grid number is N z , Obtain the two-dimensional reflection function of the target under different height planes according to different radar height values, set the three-dimensional array f(x,y,z), fill the two-dimensional reflection function data of the target under different height planes into the three-dimensional array according to the height value, The 3D imaging result of the final target is obtained.
[0081] Through the simulation test of the embodiment of the present invention, the near-field circular 3D imaging algorithm proposed by the present invention, compared with the existing algorithm, solves the angle limitation of the spherical wave focusing convolution integral method, and obtains the 3D imaging result of the target , Improve the calculation speed.


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