阅读说明：本技术 一种电介质型复合吸收剂快速设计方法 (Rapid design method of dielectric medium type composite absorbent ) 是由 安锐 冯明 高鹏程 于 2020-08-07 设计创作，主要内容包括：本发明公开了一种电介质型复合吸收剂快速设计方法,依据电磁理论和吸波原理,对基于金属背衬的传输线模型进行简化,得到电介质吸收模型；然后对模型进行介电扫参、三维反射损耗云图投影、谐振点重绘和引入等反射率圆,得到基于等反射率圆的五维设计模型；本发明的模型及方法,不但可以评价吸收剂的吸波性能,而且还能给出改性路径,为电介质型吸收剂的选材及其后续制备提供参考和依据,加速吸收剂的研发。(The invention discloses a rapid design method of a dielectric medium type composite absorbent, which simplifies a transmission line model based on a metal backing according to an electromagnetic theory and a wave absorption principle to obtain a dielectric medium absorption model; then, conducting dielectric parameter scanning, three-dimensional reflection loss cloud picture projection, resonance point redrawing and equal-reflectivity circle introduction on the model to obtain a five-dimensional design model based on the equal-reflectivity circle; the model and the method can not only evaluate the wave absorbing performance of the absorbent, but also provide a modification path, provide reference and basis for material selection and subsequent preparation of the dielectric absorbent, and accelerate research and development of the absorbent.)

1. A method for designing a dielectric composite absorbent, comprising the steps of:

step S1, according to the electromagnetic theory and the wave absorption principle, a dielectric medium absorption model is obtained by simplifying a transmission line model based on a metal backing;

s2, fixing frequency, the imaginary part of the complex dielectric constant and the coating thickness, and performing parameter sweeping on the real part of the complex dielectric constant based on a dielectric absorption model;

step S3, projecting each three-dimensional reflection loss cloud picture obtained by scanning to obtain resonance point information;

step S4, redrawing the resonance point information to obtain an optimal design curve;

step S5, introducing equal reflectivity circles on the basis of the optimal design curve to obtain a five-dimensional design model based on the reflectivity circles; the five dimensions correspond to coating thickness, frequency band, reflectivity, real and imaginary parts of the complex dielectric constant.

2. The design method of claim 1,

in step S1, the metal-backed transmission line model is:

in the formula, Z_inIs the normalized input impedance, mu_rAnd_rrespectively showing the complex magnetic permeability and the complex dielectric constant of the material, wherein f is the frequency of electromagnetic waves, d is the thickness of the wave-absorbing material, c is the speed of light, and RL is the reflection loss;

for carbon-based material mu which can hardly be magnetized_r1, simplifying the metal-backed transmission line model yields the dielectric absorption model as follows:

3. the design method of claim 2,

in step S2, the real complex dielectric constant part' of the dielectric absorption model is 2-30 as the fixed sweep parameter, and the coating thickness d, the imaginary complex dielectric constant part "and the frequency f are respectively varied within the ranges of d being 2-5 mm, 0 <" > and f being 8.2 GHz-12.4 GHz.

4. The design method of claim 2,

in step S3, a frequency-complex permittivity imaginary part-reflectivity three-dimensional map is obtained by sweeping the complex permittivity real part, the RL peak value represents a resonance point, and a frequency value and a complex permittivity imaginary part value corresponding to the resonance point are obtained according to the position of the resonance point.

5. The design method of claim 2,

in step S3, further recording the frequency value and the imaginary value of the complex permittivity corresponding to each real complex permittivity; in step S4, the data recorded are redrawn to obtain a five-dimensional integrated optimal design curve representing the optimal absorption curves at different thicknesses in the X band.

6. The design method according to claim 5,

according to the optimal design curve of five-dimensional integration in the step S4, the strength of the absorption capacity of the dielectric absorbent is judged according to the matching degree of the complex dielectric constant and the optimal absorption curve;

if the complex dielectric constant of the material falls on the optimal absorption curve, the optimal matching is met, and the wave-absorbing characteristic of the dielectric absorbent under the current given thickness is strong;

if the complex dielectric constant of the material is close to the optimal absorption curve, the medium wave absorbing capacity of the dielectric absorbent under the current given thickness is shown, and effective electromagnetic wave absorption is possible to realize; the wave-absorbing characteristic is further improved by increasing the real part of the complex dielectric constant or reducing the imaginary part of the complex dielectric constant;

if the complex dielectric constant of the material is positioned at a point symmetrical with the optimal absorption curve, the wave absorbing property of the material is further improved by reducing the real part of the complex dielectric constant or increasing the imaginary part of the complex dielectric constant;

if the complex dielectric constant of the material is far away from the optimal absorption curve, the corresponding wave-absorbing loss peak value is smaller.

7. The design method according to claim 5,

in step S5, based on the five-dimensional integrated optimal design curve, equal-reflectivity circles with set accuracy are introduced into each optimal absorption curve with different thicknesses, and the design range of each absorption curve is increased; wherein, the loss peak value of the equal reflectivity circle is superposed with the optimal absorption curve, and the frequency of the superposed point is selected according to the range of the frequency on the optimal absorption curve.

8. The design method of claim 7,

in step S5, designing a band index by introducing an equal reflectivity circle based on the five-dimensional optimal absorption curve model; selecting equal-reflectivity resonant frequency according to the rule of absorption curves under different thicknesses;

when the reflection loss value is larger and larger, increasing the equal reflectivity circle based on the frequency points;

when equal reflectivity circles at different frequencies are respectively intersected, the wave-absorbing characteristics of the material can be accurately evaluated based on a five-dimensional design model of the reflectivity circles under the reflection loss corresponding to the frequencies.

Technical Field

The invention belongs to the technical field of wave-absorbing materials, and particularly provides a method for quickly designing a dielectric medium type wave-absorbing material.

Background

The dielectric medium type absorbent has the characteristics of excellent dielectric loss, various microstructures, excellent mechanical characteristics, good chemical stability, lower specific gravity and the like, but has the defects of poor interface impedance matching, single microwave loss form, weak low-frequency absorption and narrow effective absorption band, and is difficult to meet the urgent requirements of modern combat aircrafts on thinness, lightness, width and strength of stealth materials; in addition, the bottleneck problems of complex preparation process, small change of microstructure, poor interface wettability, difficult dispersion and the like exist, and the application of the dielectric material in the stealth field is severely restricted.

The dielectric wave-absorbing composite material serving as the novel absorbent enhances the wave-absorbing effect, reduces the coating difficulty, improves the limitation of the Snoek's law, and easily meets the urgent requirements of ' thin, light, wide and strong ' of aircraft stealth materials. However, the research and development of the current novel dielectric composite absorbent are mainly based on scientific intuition of researchers and a large number of repeated 'trial and error' experiments, a clear design path is not provided, the traditional transmission line model is a comprehensive macroscopic model, the contribution and weight of the dielectric to the reflectivity cannot be reflected intuitively, and the research and development efficiency is low.

The document "Development of Analytical Approach to microwave Absorption composite materials" Mishra V, etc. IEEEtransactions on Magnetics,2017, PP (99):1-1, proposes a composite material prediction model of reflection loss and Absorption bandwidth according to index requirements, optimizes target reflectivity and frequency band through genetic algorithm to obtain dielectric parameters and magnetic permeability meeting certain conditions, and predicts the proportion of each material in the composite material by using a mixed medium model. The result shows that the composite material prepared according to the optimized dielectric parameters and magnetic permeability has good absorptivity in the X wave band.

In the literature, "optimal design method of nano-Composite radio absorption structure in the X-band frequency range considering dielectric properties of X-band)" choice I, Composite Structures,2015,119(jan.):218-226, an optimal design method of dielectric properties and electromagnetic absorption properties is proposed, in this study, a designable window for real part of complex dielectric constant-dielectric loss tangent of nano-Composite material is developed for dielectric properties of nano-Composite material, and glass fiber/epoxy resin/carbon black nano-Composite material is prepared for verification, and the measurement result shows that the electromagnetic absorption properties obtained by theoretical calculation and actual measurement are basically consistent.

The document "a Voltage-Boosting linear energy Absorption a Low-Frequency, flexible electromagnetic Wave Absorption Device (a Voltage Boosting Strategy capable of realizing a Low-Frequency flexible electromagnetic Wave Absorption Device)" Hualiang et al.

Patent application CN103399975A discloses an optimization method for calculating wave-absorbing impedance of metal backing electromagnetic wave-absorbing material, which combines a matching thickness model with a transmission line theory to enable the impedance matching optimization of the electromagnetic wave-absorbing material to be more efficient, enable the preparation of the wave-absorbing material to be rapidly and accurately completed, and is suitable for various electromagnetic wave-absorbing composite materials.

Patent application CN108805367A discloses a wave-absorbing material optimal matching design method based on a self-adaptive algorithm, and a standard artificial bee colony algorithm is optimized by using a self-adaptive strategy and a global guide neighborhood search strategy. Compared with the traditional intelligent algorithm, the self-adaptive search algorithm can effectively improve the optimization efficiency of the optimal matching of the wave-absorbing material and effectively balance the exploration and development capabilities of the algorithm.

Patent application CN103177142A discloses a method and system for designing artificially synthesized materials, which can be designed quickly and effectively, with high design efficiency and without missing critical peak values, so as to quickly obtain the optimal value, which is beneficial to large-scale industrial production.

The above prior art development of composite absorbents is mainly based on the following two forms: 1) complex dielectric constant and complex permeability under certain conditions are met; 2) the curve relation graph under certain conditions is satisfied. Although the two models can improve the research and development efficiency of the dielectric medium type composite wave-absorbing material, the dimensions covered by the models and the applicable scope are insufficient, the design path and the modification direction of the material cannot be intuitively reflected, and the problem of low research and development efficiency of the dielectric medium type absorbent cannot be effectively solved.

Disclosure of Invention

The invention provides a rapid design method of a dielectric medium type composite absorbent, which solves the problem of low research and development efficiency of the dielectric medium type absorbent through a five-dimensional (thickness, frequency band, reflectivity, real part and imaginary part of complex dielectric constant) integrated design model, and provides reference and basis for material selection and subsequent preparation of the dielectric medium type absorbent.

In order to achieve the above object, an aspect of the present invention is to provide a method for designing a dielectric composite absorbent, including the steps of:

s1, simplifying a transmission line model of the metal backing according to an electromagnetic theory and a wave absorption principle to obtain a dielectric medium absorption model;

s2, fixing frequency, the imaginary part of the complex dielectric constant and the coating thickness, and performing parameter sweeping on the real part of the complex dielectric constant based on a dielectric absorption model;

step S3, projecting each three-dimensional reflection loss cloud picture obtained by scanning parameters to obtain resonance point information;

step S4, redrawing the resonance point information to obtain an optimal design curve;

and step S5, introducing equal reflectivity circles on the basis of the optimal design curve to obtain a five-dimensional design model based on the reflectivity circles.

Preferably, in step S1, the metal-backed transmission line model is as follows:

in the formula, Z_inIs the normalized input impedance, mu_rAnd_rrespectively showing the complex permeability and the complex dielectric constant of the material, f is the frequency of electromagnetic waves, d is the thickness of the wave-absorbing material, c is the speed of light, and RL is the reflectionAnd (4) loss.

The dielectric absorption model can be obtained by a metal-backed transmission line model for carbon-based materials μ that are hardly magnetizable_r1, the transmission line model for metal backing can be simplified as:

preferably, in step S2, the dielectric absorption model (real complex permittivity part ' ═ 2 ~ 30) is used as the fixed sweep parameter, and the coating thickness d, the imaginary complex permittivity part ' and the frequency f are respectively varied within the ranges of 2 ≦ d ≦ 5mm, 0< "< ' > and 8.2GHz ≦ f ≦ 12.4GHz (X-band).

Preferably, in step S3, a three-dimensional graph of frequency-complex permittivity imaginary part-reflectivity is obtained by sweeping the real complex permittivity part, the RL peak value represents a resonance point (corresponding to an optimal absorption point), and the frequency value and the complex permittivity imaginary part value corresponding to the resonance point can be obtained according to the position of the resonance point.

Preferably, in step S3, the frequency value and the imaginary value of the complex permittivity corresponding to each real complex permittivity are recorded; in step S4, redrawing the data according to the recorded data to obtain a five-dimensional integrated optimal design curve to represent the optimal absorption curves at different thicknesses in the X band; the five dimensions correspond to thickness, frequency band, reflectivity, real and imaginary parts of the complex permittivity.

Preferably, the strength of the absorption capacity of the dielectric absorbent is judged according to the optimal design curve of the five-dimensional integration in step S4 by the matching degree of the complex dielectric constant and the optimal absorption curve;

if the complex dielectric constant of the material falls on the optimal absorption curve, the optimal matching is met, and the wave-absorbing characteristic of the dielectric absorbent under the current given thickness is strong;

if the complex dielectric constant of the material is close to the optimal absorption curve, the medium wave absorbing capacity of the dielectric absorbent under the current given thickness is shown, and effective electromagnetic wave absorption is possible to realize; the wave-absorbing characteristic is further improved by increasing the real part of the complex dielectric constant or reducing the imaginary part of the complex dielectric constant;

if the complex dielectric constant of the material is positioned at a point symmetrical with the optimal absorption curve, the wave absorbing property of the material is further improved by reducing the real part of the complex dielectric constant or increasing the imaginary part of the complex dielectric constant;

if the complex dielectric constant of the material is far away from the optimal absorption curve, the corresponding wave-absorbing loss peak value is smaller.

Preferably, in step S5, based on the five-dimensional integrated optimal design curve, a constant reflectance circle with a certain precision is introduced into the optimal absorption curve at each different thickness, so as to increase the design range of each absorption curve. Wherein, the loss peak value of the equal reflectivity circle is superposed with the optimal absorption curve, and the frequency of the superposed point is selected according to the range of the frequency on the optimal absorption curve.

Preferably, in step S5, on the basis of the five-dimensional optimal absorption curve model, an equal reflectivity circle is introduced to design the band index; selecting equal-reflectivity resonant frequency according to the rule of absorption curves under different thicknesses; when the reflection loss value is larger and larger, increasing the equal reflectivity circle based on the frequency points; when equal reflectivity circles at different frequencies are respectively intersected, the wave-absorbing characteristics of the material can be accurately evaluated based on a five-dimensional design model of the reflectivity circles under the reflection loss corresponding to the frequencies.

Compared with the prior art, the invention has the following advantages:

the method obtains a five-dimensional design model based on the equal reflectivity circle by five steps of deriving a dielectric absorption model, dielectric parameter sweeping, three-dimensional reflection loss cloud picture projection, redrawing resonance points and introducing the equal reflectivity circle, and has the following advantages: (1) the method of the invention contains more variable dimensions, and can design materials according to different indexes; (2) the method can definitely give the design path of the material, namely the raw material obtains the absorbent with the index to be met by increasing the parameters; (3) the material was evaluated for its absorbency. In conclusion, the model of the invention not only can evaluate the wave-absorbing performance of the absorbent, but also can provide a modification path and adjust the dielectric parameters and the thickness of the evaluated absorbent to achieve the target wave-absorbing performance, thereby providing reference and basis for material selection and subsequent preparation of the dielectric absorbent.

Drawings

FIG. 1 is a flow chart of a method for constructing a rapid design model of dielectric composite absorber in accordance with the present invention;

FIG. 2 is a frequency-complex permittivity imaginary part-reflectivity three-dimensional cloud in accordance with the present invention;

FIG. 3 is an optimal absorption curve for five-dimensional integration in the present invention;

fig. 4 is a design model based on the equal reflectivity circle in the present invention.

Detailed Description

The present invention will now be further described by way of the following detailed description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings.

The design method of the dielectric medium type composite absorbent of the invention is based on the electromagnetic theory and the wave absorption principle, and based on the transmission line model of the metal backing, the model is simplified to obtain the dielectric medium absorption model; and then carrying out dielectric parameter scanning, three-dimensional reflection loss cloud picture projection, resonance point redrawing and equal-reflectivity circle introduction on the dielectric model to obtain a five-dimensional design model based on the equal-reflectivity circle.

As shown in fig. 1, the method of the present invention comprises the following processes:

step S1, dielectric medium absorption model derivation based on electromagnetic theory and wave absorption principle

According to the electromagnetic theory and the wave-absorbing principle, a transmission line model based on a metal backing only needs to consider the complex dielectric constant and ignore the complex permeability aiming at the dielectric wave-absorbing material. From which a dielectric absorption model is derived. The metal-backed transmission line model is as follows:

in the formula, Z_inIs normalizedNormalized input impedance, mu_rAnd_rrespectively showing the complex permeability and the complex dielectric constant of the material, wherein f is the frequency of electromagnetic waves, d is the thickness of the wave-absorbing material, c is the speed of light, and RL is the reflection loss.

The dielectric absorption model is as follows:

step S2, fixing frequency, imaginary part of complex dielectric constant and coating thickness, and performing parameter sweep on the real part of complex dielectric constant based on a dielectric absorption model:

the dielectric absorption model (the real part of the complex dielectric constant is 2-30) is used as a fixed sweep parameter, and the thickness d of the coating, the imaginary part of the complex dielectric constant and the frequency f are respectively changed within the ranges of d being more than or equal to 2 and less than or equal to 5mm, f being more than or equal to 0< "> and 8.2GHz and less than or equal to 12.4GHz (X-band).

Step S3, projecting each scanned three-dimensional reflection loss cloud map to obtain resonance point information as shown in fig. 2, where the RL peak represents a resonance point, and a frequency value and an imaginary value of the complex dielectric constant corresponding to the resonance point can be obtained according to the position of the resonance point. And recording the corresponding frequency value and the imaginary part value of the complex dielectric constant under each real part of the complex dielectric constant.

Step S4, redrawing the resonance point information to obtain an optimal design curve:

the five dimensions correspond to thickness, frequency band, reflectivity, real part and imaginary part of complex dielectric constant; fig. 3 is a five-dimensional integrated optimal absorption curve, which shows the optimal absorption curves at different thicknesses in the X-band. In this example, the reflectance range of the optimal absorption curve is-50.45 to-81.21 dB, which shows that the absorption efficiency of the whole optimal absorption curve is very high. There are only one optimum absorption curve for d 2mm and d 3mm and 2 for d 4mm and d 5mm, the reason for the multiple optimum absorption curves is the periodic nature of the 1/4 wavelength model. And d 2mm and d 3mm make it possible to produce a plurality of optimum absorption curves with a real part of the complex permittivity higher than 30.

Briefly, the absorption capacity of the dielectric absorber can be determined by how well its complex dielectric constant matches the optimal absorption curve. As shown in fig. 3, when the complex dielectric constant falls on the optimal absorption curve, the best match is satisfied, which indicates that the material exhibits stronger wave-absorbing property at the given thickness. If the complex dielectric constant is closer to the optimal absorption curve, indicating that the dielectric absorber has a moderate absorbing capacity at a given thickness, it is possible to achieve effective electromagnetic wave absorption (RL < -10 dB). In order to improve the wave-absorbing property of the material, the real part of the complex dielectric constant is increased or the imaginary part of the complex dielectric constant is decreased, and similarly, if the complex dielectric constant of the material is at a point symmetrical to the optimal absorption curve, the real part of the complex dielectric constant is decreased and the imaginary part of the complex dielectric constant is increased. When the complex dielectric constant is far away from the optimal absorption curve, the corresponding wave-absorbing loss peak value is suggested to be smaller.

Step S5, introducing equal reflectivity circle on the basis of the optimal design curve

On the basis of a five-dimensional optimal absorption curve model, an equal reflectivity circle is introduced to accurately design the band index and provide a modification path for the absorber to widen the working band. According to the law of absorption curves under different thicknesses, equal-reflectivity resonant frequency is selected, and by taking an optimal absorption curve model with d being 3mm as an example, three frequency points of 9GHz, 10GHz and 11GHz are selected to make an equal-reflectivity circle. If a certain reflection loss evaluation system is more accurate and the reflection loss value is larger and larger, the equal reflectivity circle based on the frequency point needs to be continuously increased, as shown in fig. 4, wherein equal-5 dB, -10dB and-15 dB circles at three different frequencies are respectively intersected to show that the model can accurately evaluate the wave-absorbing characteristic of the material with the reflection loss of-15 dB.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.