Three-dimensional electromagnetic imaging method based on contrast source inversion algorithm

An inversion algorithm and three-dimensional electromagnetic technology are applied in the radio wave measurement system, radio wave reflection/re-radiation, and use of re-radiation, etc., to avoid forward calculation, benefit efficiency and stability, and improve quality.

Inactive Publication Date: 2013-01-02
TIANJIN POLYTECHNIC UNIV
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Problems solved by technology

There is currently no nonlinear algorithm that satisfies all of the above conditions

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  • Three-dimensional electromagnetic imaging method based on contrast source inversion algorithm
  • Three-dimensional electromagnetic imaging method based on contrast source inversion algorithm
  • Three-dimensional electromagnetic imaging method based on contrast source inversion algorithm

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Embodiment

[0059] There are 2 non-uniform dielectric targets: "twocubes" and "cubespheres". The three-dimensional measured electromagnetic data are all obtained in the darkroom, where the transmitting antenna is a parabolic antenna and the receiving antenna is a horn antenna. The test settings are as follows: figure 2 As shown, taking spherical coordinates as an example, the transmitting antenna moves on a spherical surface with a distance of 1.796 meters from the center of the test setup; the azimuth angle φ s (azimuthal angle) changes from 0° to 320°, each change is 40°; polar angle θ s (polar angle) is changed from 50° to 150°, and each change is 15°; thus, a total of 81 transmitting antennas are distributed on a spherical surface with a radius of 1.796 meters. The distance between the receiving antenna and the center of the test setup is also 1.796 meters; the azimuth angle φ r =90°, which is located on the plane of z=0; polar angle θ r Expressed as follows:

[0060] θ r = θ s ...

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Abstract

An application of three-dimensional imaging to the field of practical engineering such as nondestructive inspection, medical imaging, ground surface detection, geophysical exploration and the like is of great potential. As approximate treatment is adopted in a linear imaging algorithm, a reconstructed image is limited in precision and accuracy; and while in a non-linear algorithm such as a contrast source inversion (CSI) algorithm, position, shape and material parameters of an image such as an interested target can be gradually improved in an iteration process, and an image most similar to the interested target is reconstructed at last. The invention discloses a nonlinear imaging method for multi-frequency multi-transceiver three-dimensional electromagnetic actual measurement data based on the contrast source inversion algorithm combining a frequency hopping method with a regularization method. As forward calculation is not needed, a calculation amount for calculating a three-dimensional dyadic green function operator and a conjugate operator of the function operator in the iteration process is controllable, and a reconstruction result proves that the method can be widely applied to the field of practical applications with requirements of high-precision and high-resolution imaging due to precision and feasibility of an application to three-dimensional electromagnetic imaging.

Description

technical field [0001] The application of 3D microwave imaging in practical engineering fields such as non-destructive testing, medical imaging, surface detection, and geophysical exploration has great potential. Electromagnetic imaging is an inverse problem with nonlinear and ill-conditioned characteristics, which is difficult to solve, so accurate imaging algorithms are urgently needed. At present, most of the mature algorithms used in practical applications are linear algorithms. Due to the use of approximate processing, the resolution and accuracy of the reconstructed image are very limited. The nonlinear algorithm can gradually improve the image in the iterative process, such as the position, shape and material physical parameters of the target of interest, and finally obtain the image that is the closest to the target of interest. The ongoing National 863 Program - "Application and Research on Scientific Data of Lunar Exploration Engineering" clearly proposes the resear...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S7/41G01S13/89
Inventor 缪竟鸿戈立军耿磊
Owner TIANJIN POLYTECHNIC UNIV
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