A method of coating a honeycomb array with an additional metal backing to make it electromagnetically parameter equivalent

Abstract

The application provides an electromagnetic parameter equivalent method for a coated honeycomb composite material array with a metal backing, and relates to the field of electromagnetic calculation. The method comprises the following steps: S1, constructing a unit model and extracting S parameters; S2, constructing a relationship formula of reflection coefficients S 11 and input impedance Z in under TE and TM polarized waves, and calculating the input impedance; S3, inverting to obtain anisotropic equivalent permittivity and permeability; S4, performing phase compensation to obtain corrected anisotropic equivalent permittivity and permeability, and completing an anisotropic equivalent electromagnetic model of the coated honeycomb composite material array with the metal backing. The method of the application can equivalently convert the coated honeycomb composite material into an anisotropic uniform medium, and has good precision under multi-angle, wide frequency band and multi-polarization.

Description

Technical Field

[0001] The invention belongs to the field of computational electromagnetic technology, and in particular relates to an electromagnetic parameter equivalence method for a coated honeycomb composite material array with an additional metal backing. Background Art

[0002] Electromagnetic stealth performance has become a core design objective for modern aircraft. Honeycomb composites, as a structural electromagnetic stealth material, are widely used in radar stealth due to their excellent load-bearing capacity and controllable radiation scattering properties. Accurately constructing an equivalent electromagnetic parameter calculation model for electromagnetic stealth materials to improve their efficient structural design capabilities and maximize their design advantages is a highly challenging fundamental research topic and a crucial issue that urgently needs to be addressed in the development of structured electromagnetic composite stealth materials. Summary of the Invention

[0003] The present invention provides an electromagnetic parameter equivalence method for a coated honeycomb composite material array with an additional metal backing, which realizes the construction of a high-precision electromagnetic parameter equivalent model of the honeycomb composite material array under multi-angle, wide-band and multi-polarization conditions.

[0004] The technical solution adopted in the present invention is as follows:

[0005] A method for electromagnetic parameter equivalence of a coated honeycomb composite material array with an additional metal backing, characterized by comprising the following steps:

[0006] S1. Build a model of a coated honeycomb composite array with a metal backing and extract S parameters.

[0007] In the coated honeycomb composite material array, the honeycomb unit is composed of a honeycomb core layer and a coating medium on its surface. Both the honeycomb core layer and the coating medium are lossy materials with dielectric loss and magnetic loss. The unit length of the honeycomb unit is a, the inner side length is r, and the thickness is h. The thickness of the coating medium is t. The thickness of the metal copper substrate attached to the bottom of the honeycomb unit is d.

[0008] Establish a honeycomb unit simulation model and set periodic boundary conditions to extract the S parameters of the honeycomb unit; the S parameters include the reflection coefficient S under vertical and oblique incidence angles of TE and TM polarized waves in the required frequency band. 11 Amplitude and phase data.

[0009] S2. Construction of a coated honeycomb composite array with additional metal backing and reflection coefficient S under TE and TM polarization waves 11 and input impedance Z in The relationship:

[0010]

[0011] Among them, θ i Indicates the incident angle of the electromagnetic wave.

[0012] Substitute the S parameters obtained in step S1 into formula (1) to obtain the input impedance of TE and TM polarized waves under vertical incidence and oblique incidence

[0013] S3. According to the input impedance Z under TE and TM polarization waves in The anisotropic equivalent dielectric constant and magnetic permeability of the honeycomb composite material array are obtained by inversion:

[0014]

[0015] Among them, ε x , ε y , ε z They represent the anisotropic equivalent dielectric constants in the x, y, and z directions in the global coordinate system, μ x 、μ y 、μ z They represent the magnetic permeabilities in the x, y, and z directions in the global coordinate system, k0 is the wave vector in vacuum, and j is the imaginary basic unit.

[0016] S4. Since the honeycomb thickness causes periodic mutations in the transmission coefficient angle, resulting in a phase discontinuity problem in the transmission coefficient, it is necessary to compensate for the phase. Substituting the anisotropic electromagnetic parameters initially obtained from formula (2) into formula (3), the four transmission coefficients under vertical and oblique incidence of TE and TM polarized waves are obtained:

[0017]

[0018] Among them, T TE 、T TM represent the transmission coefficients under TE and TM polarization waves, respectively, TE 、φ TM Represents T TE 、T TM The phase angle, m and n are the phase compensation coefficients.

[0019] Phase compensation is performed when the transmission coefficient phase suddenly changes, so that the transmission coefficient T under vertical incidence and oblique incidence is TE 、T TM The phase decreases monotonically with frequency to ensure the continuity of the transmission coefficient phase; then the phase-compensated T of formula (3) is TE 、T TM The exponential terms are combined and the equations are solved to finally obtain the modified anisotropic equivalent dielectric constant ε x , ε y , εz , magnetic permeability μ x 、μ y 、μ z , completed the anisotropic equivalent electromagnetic model of the coated honeycomb composite array with metal backing.

[0020] Furthermore, in step S1, a honeycomb unit simulation model is established using HFSS electromagnetic simulation software.

[0021] Furthermore, in step S1, the oblique incident angle ranges from 20° to 70°.

[0022] The beneficial effects of the present invention are:

[0023] Since honeycomb absorbing materials are composed of multiple materials, there are difficulties in electromagnetic parameter modeling in practical applications. In addition, there are often multi-scale problems in the simulation of aircraft loaded with honeycomb absorbing materials. Therefore, in the electromagnetic simulation process, problems such as a large number of meshes and a large number of unknown quantities are usually encountered.

[0024] The present invention extracts the reflection coefficient S of the coated honeycomb composite material array with a metal backing. 11 The input impedance of the honeycomb array is calculated, and the accurate anisotropic equivalent electromagnetic parameters (ε x , ε y , ε z , μ x 、μ y 、μ z The present invention can effectively solve the problem of difficulty in electromagnetic parameter modeling of honeycomb composite materials in practical applications, and effectively save simulation computing resources based on honeycomb composite materials, which is conducive to improving the design efficiency of honeycomb electromagnetic stealth materials and maximizing the design advantages of structured stealth materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the present invention.

[0026] Figure 1 It is a schematic diagram of the process of the technical solution of the present invention;

[0027] Figure 2 Schematic diagram of a honeycomb composite material structure unit in an embodiment;

[0028] Figure 3 Schematic diagram of input impedance under vertical incidence in the embodiment;

[0029] Figure 4Schematic diagram of input impedance at 30° oblique incidence in the embodiment;

[0030] Figure 5 This is a preliminary honeycomb equivalent electromagnetic parameter diagram obtained in the embodiment;

[0031] Figure 6 This is a diagram of honeycomb equivalent electromagnetic parameters obtained after phase compensation in the embodiment;

[0032] Figure 7 This is a comparison chart of the reflectivity of the honeycomb unit and the equivalent uniform dielectric unit in the embodiment at 2 to 18 GHz;

[0033] Figure 8 This is a comparison chart of the RCS of a coated honeycomb array with a metal backing and an equivalent uniform dielectric flat plate at 4 GHz in the embodiment;

[0034] Figure 9 This is a comparison chart of the RCS of the coated honeycomb array with additional metal backing and the equivalent uniform dielectric flat plate at 12 GHz in the embodiment. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] This embodiment provides an electromagnetic parameter equivalent method for a coated honeycomb composite material array with an additional metal backing, such as Figure 1 As shown, the following steps are included:

[0037] S1. Build a model of a coated honeycomb composite array with a metal backing and extract S parameters.

[0038] like Figure 2 As shown in the figure, in the coated honeycomb composite material array, the honeycomb unit is composed of a honeycomb core layer and a coating medium on its surface. The dielectric constant of the honeycomb core layer is 3-0.9j, and the magnetic permeability is 1-0.1j. The dielectric constant of the coating medium is 7-2.8j, and the magnetic permeability is 3-0.6j. Assume that the unit length a of the honeycomb unit is 15mm, the inner side length r is 4mm, and the height h is 20mm; the thickness t of the coating medium is 0.5mm; the thickness d of the metal copper substrate attached to the bottom of the honeycomb unit is 2mm.

[0039] The HFSS electromagnetic simulation software was used to establish a honeycomb unit simulation model and set periodic boundary conditions to extract the S parameters of the honeycomb unit. The S parameters include the reflection coefficient S under vertical incidence of TE and TM polarized waves and 30° oblique incidence angle in the 2-18 GHz frequency band. 11 Amplitude and phase data.

[0040] S2. Construction of a coated honeycomb composite array with additional metal backing and reflection coefficient S under TE and TM polarization waves 11 and input impedance Z in The relationship:

[0041]

[0042] Among them, θ i Indicates the incident angle of the electromagnetic wave.

[0043] Substitute the S parameters obtained in step S1 into formula (1) to obtain the input impedance of TE and TM polarized waves under vertical incidence and oblique incidence The results are as follows Figure 3 、 Figure 4 shown.

[0044] S3. According to the input impedance Z under TE and TM polarization waves in The anisotropic equivalent dielectric constant and magnetic permeability of the honeycomb composite material array are obtained by inversion:

[0045]

[0046] Among them, ε x , ε y , ε z They represent the anisotropic equivalent dielectric constants in the x, y, and z directions in the global coordinate system, μ x 、μ y 、μ z They represent the magnetic permeability in the x, y, and z directions in the global coordinate system, k0 is the wave vector in vacuum, and j is the basic unit of imaginary numbers. The preliminary results of the honeycomb equivalent electromagnetic parameters are as follows: Figure 5 shown.

[0047] S4. Since the honeycomb thickness causes periodic mutations in the transmission coefficient angle, which leads to the problem of phase discontinuity of the transmission coefficient, phase compensation is required.

[0048] Substituting the anisotropic electromagnetic parameters initially obtained from formula (2) into formula (3), we obtain the four transmission coefficients under vertical and oblique incidence of TE and TM polarized waves:

[0049]

[0050] Among them, T TE 、T TM represent the transmission coefficients under TE and TM polarization waves, respectively, TE 、φ TM Represents T TE 、T TM The phase angle, m and n are the phase compensation coefficients.

[0051] Phase compensation is performed when the transmission coefficient phase suddenly changes, so that the transmission coefficient T under vertical incidence and oblique incidence is TE 、T TM The phase decreases monotonically with frequency to ensure the continuity of the transmission coefficient phase; then the phase-compensated T of formula (3) is TE 、T TM The exponential terms are combined and the equations are solved to obtain the modified anisotropic equivalent dielectric constant ε. x , ε y , ε z , magnetic permeability μ x 、μ y 、μ z , completed the anisotropic equivalent electromagnetic model of the coated honeycomb composite array with metal backing.

[0052] Figure 6 The composite honeycomb material of this embodiment is equivalent to the electromagnetic parameters of a homogeneous medium, and the dielectric constant and magnetic permeability of the homogeneous medium are anisotropic and have dispersion characteristics.

[0053] Figure 7 The figure is a comparison of the reflectivity of the honeycomb unit and the equivalent uniform dielectric unit in the range of 2 to 18 GHz. The reflectivity of the honeycomb unit and the equivalent uniform dielectric unit is consistent in dual polarization and broadband, which verifies the rationality of the equivalent electromagnetic parameters of the present invention.

[0054] Figure 8 、 9 The RCS data of the coated honeycomb composite material array with metal backing and the equivalent uniform dielectric plate of the present invention were compared under the incidence of two polarized waves at typical frequencies of 4GHz and 12GHz. The array size is 100mm×100mm. It can be seen that at the typical frequencies of 4GHz and 12GHz, the TE and TM dual polarized waves have a high incidence angle θ. i In the range of -80° to 80°, the scattering data of the coated honeycomb composite array with additional metal backing and the equivalent uniform medium show good consistency.

[0055] Compared with the traditional method, the advantages of this invention are: in the process of extracting honeycomb equivalent parameters, it avoids the large measurement errors caused by measuring the geometric parameters and electromagnetic parameters of honeycomb components. In addition, combined with the use scenario of honeycomb with metal backplane, it only requires TE and TM polarized waves with vertical incidence and oblique incidence angle θ. i The reflection coefficient S under 11Amplitude and phase data can be used to equate a honeycomb to an anisotropic, homogeneous plate. Under multi-angle incident electromagnetic waves, this equivalent accuracy exceeds that of isotropic and quasi-static anisotropic equivalent methods. Furthermore, based on an efficient and simple phase compensation method, this approach facilitates the extraction of equivalent parameters for honeycombs of arbitrary thickness.

[0056] It is worth noting that the present invention can be carried out in a wider frequency range and is not limited by the thickness of the honeycomb. The dielectric constant and magnetic permeability of the honeycomb core and the filling medium can be any isotropic medium.

Claims

1. A method for electromagnetic parameter equivalence of a coated honeycomb composite material array with an additional metal backing, characterized in that: The following steps are involved: S1. Construct a unit simulation model of a coated honeycomb composite array with a metal backing and extract S parameters; S2. Construction of a coated honeycomb composite array with additional metal backing and reflection coefficient S under TE and TM polarization waves 11 and input impedance Z in The relationship: Among them, θ i represents the incident angle of electromagnetic wave; Substitute the S parameters obtained in step S1 into formula (1) to obtain the input impedance of TE and TM polarized waves under vertical incidence and oblique incidence S3. The input impedance Z under TE and TM polarization waves obtained in step S1 is in Substituting into formula (2), the anisotropic equivalent dielectric constant and magnetic permeability of the honeycomb composite material array are obtained by inversion: Among them, ε x , ε y , ε z They represent the anisotropic equivalent dielectric constants in the x, y, and z directions in the global coordinate system, μ x 、μ y 、μ z denote the magnetic permeability in the x, y, and z directions in the global coordinate system, k0 is the wave vector in vacuum, and j is the imaginary basic unit; S4. Substitute the anisotropic electromagnetic parameters obtained from formula (2) into formula (3) to obtain the four transmission coefficients under vertical and oblique incidence of TE and TM polarized waves: Among them, T TE 、T TM represent the transmission coefficients under TE and TM polarization waves, respectively. Represents T TE 、T TM The phase angle, m and n are the phase compensation coefficients; Phase compensation is performed when the transmission coefficient phase suddenly changes, so that the transmission coefficient T under vertical incidence and oblique incidence is TE 、T TM The phase decreases monotonically with frequency to ensure the continuity of the transmission coefficient phase; Then the phase-compensated T in formula (3) is TE 、T TM The exponential terms are combined and the equations are solved to finally obtain the modified anisotropic equivalent dielectric constant ε x , ε y , ε z , magnetic permeability μ x 、μ y 、μ z , completed the anisotropic equivalent electromagnetic model of the coated honeycomb composite array with metal backing.

2. The electromagnetic parameter equivalent method of a coated honeycomb composite material array with an additional metal backing according to claim 1, characterized in that: In step S1, the honeycomb unit of the coated honeycomb composite material array is composed of a honeycomb core layer and a coating medium on its surface, and both the honeycomb core layer and the coating medium are lossy materials with dielectric loss and magnetic loss; Assume that the length of the honeycomb unit is a, the inner side length is r, and the thickness is h; the thickness of the coating medium is t; and the thickness of the metal copper substrate attached to the bottom of the honeycomb unit is d.

3. The electromagnetic parameter equivalent method of a coated honeycomb composite material array with an additional metal backing as claimed in claim 2, characterized in that: In step S1, a honeycomb unit simulation model is established and periodic boundary conditions are set to extract the S parameters of the honeycomb unit; the S parameters include the reflection coefficients S under vertical and oblique incidence angles of TE and TM polarized waves in the required frequency band. 11 Amplitude and phase data.

4. The electromagnetic parameter equivalent method of a coated honeycomb composite material array with an additional metal backing as claimed in claim 3, characterized in that: In step S1, a honeycomb unit simulation model is established using HFSS electromagnetic simulation software.

5. The electromagnetic parameter equivalent method of a coated honeycomb composite material array with an additional metal backing as claimed in claim 4, characterized in that: In step S1 , the oblique incident angle ranges from 20° to 70°.

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