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Scattered field determining method of nonuniform medium target body

A technology of non-uniform medium and determination method, applied in radio wave measurement systems, instruments, etc., can solve the problems of troublesome judgment process, non-uniform medium scattering, inability to save memory, etc., and achieve the effect of saving memory and reducing the number of

Active Publication Date: 2019-05-17
XIDIAN UNIV
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  • Abstract
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  • Claims
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Problems solved by technology

[0003] Zhang Zhanfang of Nanjing University of Science and Technology mentioned a half-SWG basis function in his paper "Electromagnetic Scattering Analysis of Discontinuous Galerkin Time Domain Volume Integral Equation Method", and discussed the boundary processing methods in two cases, The first is the boundary treatment between different dielectric constant units, and the second is the boundary treatment of the medium unit in contact with the air. The SWG basis function originally defined in two small tetrahedrons is defined in each small tetrahedron. above, it can be used to solve the problem of scattering in inhomogeneous media, but this method needs to judge whether the small tetrahedron is at the boundary, the judgment process is cumbersome, and there is only one basis function between the two small tetrahedrons, the number of small tetrahedron units requires Relatively high, can not save memory

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  • Scattered field determining method of nonuniform medium target body
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  • Scattered field determining method of nonuniform medium target body

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Embodiment 1

[0024] The research on the electromagnetic characteristics of medium targets is an important application research in the field of computational electromagnetics. It is used in radar system design, target recognition and classification, detection of space suspended medium objects, identification and stealth of military complex medium targets, and reduction of radar scattering cross section. Target stealth has become an important engineering application problem in military and communication. When solving the problem of medium body scattering, in order to better simulate the shape of medium targets, relatively fine subdivision rules are often used, and the requirements of non-uniform media for subdivision It is more strict, and conformal subdivision technology is required. In this way, the mesh must be divided according to the entity with the largest dielectric constant, resulting in a particularly small side length of the small tetrahedron, resulting in a huge unknown quantity, an...

Embodiment 2

[0046] The method for determining the electromagnetic scattering field of the heterogeneous medium target is the same as embodiment 1, and the establishment of the heterogeneous medium target volume integral equation described in step (3) includes the following steps:

[0047] E(r)-ZL(J)=E i (r)

[0048] in:

[0049]

[0050] J(r)=jω∈ 0 [∈ r (r)-1]E(r)

[0051]

[0052] In the formula:

[0053] E(r) represents the electric field strength inside the dielectric body.

[0054] Z represents the wave impedance of free space.

[0055] E. i (r) represents the incident field.

[0056] k represents the wave number in free space.

[0057] G represents the Green's function of free space.

[0058] ∈ 0 Indicates the permittivity of free space.

[0059] ∈ r Indicates the dielectric constant of the medium.

[0060] r represents the observation point and r' represents the source point.

Embodiment 3

[0062] The method for determining the electromagnetic scattering field of the heterogeneous medium object is the same as embodiment 1-2, the discretization process to the electric field intensity of each small tetrahedron described in step (4), see Figure 4 , including the following steps:

[0063] Expand the electric field strength E as:

[0064]

[0065] in:

[0066]

[0067] N represents the number of small tetrahedra after discretization.

[0068] i represents the four vertices of the small tetrahedron, see Figure 4 , Figure 4 The four vertices in are 1,2,3,4 respectively.

[0069] a mi Indicates the area of ​​the face opposite to the i-th vertex of the small tetrahedron.

[0070] V m represents the volume of a small tetrahedron.

[0071] Represents the unit vector from the i-th vertex of the small tetrahedron to the i-th Gaussian integration point. When doing volume Gaussian integration, if the body center distance of two small tetrahedrons is d>0.1λ, ...

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Abstract

The invention discloses a scattered field determining method of a nonuniform medium target body. The scattered field determining method of the nonuniform medium target body solves the problem of determining the radar scattered cross section of the nonuniform medium target body in the field of military communication. The scattered field determining method comprises the realizing steps that the nonuniform medium target body is guided into and modeled; the four primary functions of each little tetrahedron are determined; the volume integral equation of the target body is established; the electricfield intensity of each little tetrahedron is discretized; each little tetrahedron is weighted and determined and the column vector of the electric field intensity coefficient of the target body is obtained; and the radar scattered cross section is determined through the target body equivalent current density. According to the scattered field determining method, the primary equations are definedat the four top points of the tetrahedron, non-conformal subdivision among the nonuniform medium is ignored, whether a tetrahedron unit is in contact with air or not does not need to be judged, the four primary functions are used by each little tetrahedron, and unit number and memory amount are saved. An electromagnetic scattered field and a radar scattered cross section of electrically large sizenonuniform medium target body are determined effectively, and the scattered field determining method is applied to the field of calculation electromagnetism.

Description

technical field [0001] The invention belongs to the field of electromagnetic scattering technology, and in particular relates to a calculation of electromagnetic scattering in a heterogeneous medium, in particular to a method for determining the scattering field of a target in a heterogeneous medium, which can be used for complex and non-conformal subdivision in radar target search Calculation and detection of the target medium body. Background technique [0002] The discontinuous Galerian algorithm is an electromagnetic simulation method for calculating the electromagnetic scattering of inhomogeneous media. First of all, it is necessary to model the research target, that is, to divide the target into several small tetrahedron or small hexahedron units, according to the dielectric constant ∈ of the discontinuous medium r Divide the target into several small tetrahedral units with different subdivision rules, use the volume basis function defined on a target body to carry ou...

Claims

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Application Information

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IPC IPC(8): G01S7/41
Inventor 吕志清安翔刘义朝
Owner XIDIAN UNIV
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