阅读说明：本技术 一种电磁参数测量系统及其测量方法 (Electromagnetic parameter measuring system and measuring method thereof ) 是由 陈海东 张俊 廖绍伟 车文荃 薛泉 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种电磁参数测量系统及其测量方法,其中系统包括：两个波导同轴变换器,其中一个波导同轴变换器用于输出电磁波,另一个波导同轴变换器用于接收电磁波；两个波导模块,每个波导模块包括标准矩形波导和介质填充波导,介质填充波导内设有填充介质,标准矩形波导的一端与波导同轴变换器连接,标准矩形波导的另一端与介质填充波导的一端连接；波导垫片,设有用于安放待测试样品的窗口,窗口与填充介质连接,波导垫片与介质填充波导的另一端连接。本发明提出的电磁参数测量系统,对柔性材料和/或薄片材料的电磁参数进行测试,能够同时测量多种电磁参数,提高测量的效率,可广泛应用于微波测量领域。(The invention discloses an electromagnetic parameter measuring system and a measuring method thereof, wherein the system comprises: the two waveguide coaxial converters are used for outputting electromagnetic waves, and the other waveguide coaxial converter is used for receiving the electromagnetic waves; each waveguide module comprises a standard rectangular waveguide and a medium-filled waveguide, a filling medium is arranged in the medium-filled waveguide, one end of the standard rectangular waveguide is connected with the waveguide coaxial converter, and the other end of the standard rectangular waveguide is connected with one end of the medium-filled waveguide; the waveguide gasket is provided with a window for placing a sample to be tested, the window is connected with the filling medium, and the waveguide gasket is connected with the other end of the medium filling waveguide. The electromagnetic parameter measuring system provided by the invention can be used for testing the electromagnetic parameters of the flexible material and/or the sheet material, can be used for simultaneously measuring various electromagnetic parameters, improves the measuring efficiency, and can be widely applied to the field of microwave measurement.)

1. An electromagnetic parameter measurement system, comprising:

two waveguide coaxial converters, wherein one waveguide coaxial converter is used for outputting electromagnetic waves, and the other waveguide coaxial converter is used for receiving the electromagnetic waves;

each waveguide module comprises a standard rectangular waveguide and a medium-filled waveguide, a filling medium is arranged in the medium-filled waveguide, one end of the standard rectangular waveguide is connected with the waveguide coaxial converter, and the other end of the standard rectangular waveguide is connected with one end of the medium-filled waveguide;

the waveguide gasket is provided with a window for placing a sample to be tested, the window is connected with the filling medium, and the waveguide gasket is connected with the other end of the medium filling waveguide;

the output electromagnetic wave sequentially passes through the first filling medium, the window and the second filling medium and is received by the waveguide coaxial converter.

2. An electromagnetic parameter measurement system according to claim 1, wherein the standard rectangular waveguide and the dielectric-filled waveguide in the same waveguide module are integrally designed, and the transition section between the standard rectangular waveguide and the dielectric-filled waveguide is in a multi-stage ladder structure to realize impedance matching.

3. An electromagnetic parameter measurement system according to claim 1, wherein one end of the filling medium is a multi-step structure to realize impedance matching, and the waveguide cut-off frequency between the standard rectangular waveguide and the medium-filled waveguide is the same by reducing the dimension of the wide side of the medium-filled waveguide.

4. The system of claim 1, wherein the waveguide coaxial converter, the waveguide module and the waveguide gasket are fixed by a flange, and when the waveguide coaxial converter, the waveguide module and the waveguide gasket are fixed, the other end of the filling medium is contacted with the sample to be tested to fix the sample to be tested,

the thickness of the sample to be tested is the same as that of the waveguide gasket.

5. An electromagnetic parameter measurement system according to claim 1, further comprising a TRL calibration unit for calibrating the S-parameter plane of the electromagnetic parameter measurement system and the systematic error factors.

6. An electromagnetic parameter measurement system according to claim 1, wherein the TRL calibration member comprises a reflection plate and a transmission line, the length of the transmission line is a quarter of a waveguide wavelength, and the waveguide wavelength is determined by the operating frequency of the waveguide, the cut-off wavelength of the waveguide, and the dielectric constant of the filling medium.

7. An electromagnetic parameter measuring method of an electromagnetic parameter measuring system according to claim 1, comprising the steps of:

outputting a first electromagnetic wave, wherein a second electromagnetic wave is obtained after the first electromagnetic wave penetrates through a filling medium and a sample to be tested;

receiving the second electromagnetic wave, and acquiring an S parameter of a sample to be tested according to the first electromagnetic wave and the second electromagnetic wave;

and acquiring the electromagnetic parameters of the sample to be tested according to the S parameters, wherein the electromagnetic parameters comprise at least one of complex dielectric constant, complex permeability or loss tangent.

8. The method of claim 7, wherein the acquiring the electromagnetic parameters of the sample to be tested according to the S-parameters comprises:

the S parameter has the following relationship with the reflection coefficient and the transmission coefficient:

suppose that

The reflection coefficient Γ may be expressed as:

moreover, | Γ | < 1;

from the transmission line theory, the following conclusions are drawn:

T＝e^-γd

where γ is the propagation constant, λ₀Is the operating wavelength, λ, of the electromagnetic wave_cIs the cut-off wavelength, ∈_rIs the complex dielectric constant, mu, of the sample to be measured_rIs the complex permeability of the material to be measured, Z and Z_rExpressed as the characteristic impedance of the standard rectangular waveguide and the sample region, respectively; obtaining the reflection coefficient gamma and the complex dielectric constant epsilon_rComplex magnetic permeability mu_rThe relationship between them is as follows:

obtaining a complex dielectric constant ε_rComplex magnetic permeability mu_rAnd loss tangent are expressed as follows:

wherein λ_gIs the waveguide wavelength.

9. An electromagnetic parameter measuring method according to claim 7, further comprising a compensation step, said compensation step comprising:

outputting a third electromagnetic wave, wherein the fourth electromagnetic wave is obtained after the third electromagnetic wave penetrates through a filling medium and air;

receiving the fourth electromagnetic wave, and acquiring S parameters of air according to the third electromagnetic wave and the fourth electromagnetic wave;

obtaining the dielectric constant epsilon 'of the filling medium according to the S parameter of the air'_l；

According to the dielectric constant epsilon 'of the filling medium'_lAnd compensating the electromagnetic parameters of the sample to be tested to obtain the compensated electromagnetic parameters.

10. The method according to claim 9, wherein the dielectric constant ε 'of the filling medium is obtained according to the S parameter of air'_lThe method comprises the following steps:

acquiring the dielectric constant and loss tangent of air;

according to the dielectric constant and the loss tangent of the air and the electromagnetic parameters of the air obtained by calculation, the dielectric constant epsilon 'of the medium is reversely deduced'_l；

Wherein the dielectric constant ε of air_r1.0006, the loss tangent tan θ of air is 0.

Technical Field

The invention relates to the field of microwave measurement, in particular to an electromagnetic parameter measurement system and a measurement method thereof.

Background

In the rapid development of microwave technology, researchers pay attention to the measurement and research of electromagnetic parameters of materials, and the measurement method goes through the processes from low frequency to microwave, from simple capacitance measurement to the application of a numerical calculation method. With the higher and higher application frequency of electromagnetic waves, the more and more complex and precise structure of microwave circuits or devices is further improved, and researchers have higher and higher requirements for testing and characterizing the electromagnetic parameters of materials.

Furthermore, in recent years, with the demand for miniaturization of devices, device conformability, and the like, flexible materials and sheet materials and the like have been widely used for designing microwave/millimeter wave circuits due to their excellent conformability characteristics, and from the research methods disclosed so far, there have been still few researches on measurement of electromagnetic parameters of flexible materials and sheet materials. Therefore, the problem of measuring electromagnetic parameters of flexible materials and sheet materials is urgently solved.

Disclosure of Invention

In order to solve at least one of the technical problems in the prior art to a certain extent, the present invention provides an electromagnetic parameter measuring system and a measuring method thereof.

The technical scheme adopted by the invention is as follows:

an electromagnetic parameter measurement system comprising:

the two waveguide coaxial converters are used for being connected with a vector network analyzer, wherein one waveguide coaxial converter is used for outputting electromagnetic waves, and the other waveguide coaxial converter is used for receiving the electromagnetic waves;

each waveguide module comprises a standard rectangular waveguide and a medium-filled waveguide, a filling medium is arranged in the medium-filled waveguide, one end of the standard rectangular waveguide is connected with the waveguide coaxial converter, and the other end of the standard rectangular waveguide is connected with one end of the medium-filled waveguide;

the waveguide gasket is provided with a window for placing a sample to be tested, the window is connected with the filling medium, and the waveguide gasket is connected with the other end of the medium filling waveguide;

the output electromagnetic wave sequentially passes through the first filling medium, the window and the second filling medium and is received by the waveguide coaxial converter.

Furthermore, the standard rectangular waveguide and the dielectric-filled waveguide in the same waveguide module are designed integrally, and the transition section between the standard rectangular waveguide and the dielectric-filled waveguide adopts a multi-section stepped structure to realize impedance matching.

Furthermore, one end of the filling medium adopts a multi-section stepped structure to realize impedance matching, and the same waveguide cut-off frequency between the standard rectangular waveguide and the medium filled waveguide is realized by reducing the size of the wide side of the medium filled waveguide. By reduced broadside dimension is meant herein that the broadside dimension of the overall dielectric-filled waveguide is narrower than the broadside of a standard rectangular waveguide. This achieves the same waveguide cutoff frequency between a standard rectangular waveguide and a dielectric-filled waveguide.

Furthermore, the waveguide coaxial converter, the waveguide module and the waveguide gasket are fixed through a flange plate, and when the waveguide coaxial converter, the waveguide module and the waveguide gasket are fixed, the other end of the filling medium is contacted with the sample to be tested so as to fix the sample to be tested,

the thickness of the sample to be tested is the same as that of the waveguide gasket.

Furthermore, the electromagnetic parameter measurement system also comprises a TRL calibration piece, and the TRL calibration piece is used for calibrating an S parameter plane of the electromagnetic parameter measurement system and error factors of the system.

Further, the TRL calibration member includes a reflection plate and a transmission line, the length of the transmission line is a quarter of a waveguide wavelength, and the waveguide wavelength is determined by an operating frequency of the waveguide, a cutoff wavelength of the waveguide, and a dielectric constant of the filling medium.

The other technical scheme adopted by the invention is as follows:

an electromagnetic parameter measuring method based on the electromagnetic parameter measuring system comprises the following steps:

outputting a first electromagnetic wave, wherein a second electromagnetic wave is obtained after the first electromagnetic wave penetrates through a filling medium and a sample to be tested;

receiving the second electromagnetic wave, and acquiring an S parameter of a sample to be tested according to the first electromagnetic wave and the second electromagnetic wave;

and acquiring the electromagnetic parameters of the sample to be tested according to the S parameters, wherein the electromagnetic parameters comprise at least one of complex dielectric constant, complex permeability or loss tangent.

Further, the acquiring the electromagnetic parameter of the sample to be tested according to the S parameter includes:

the S parameter has the following relationship with the reflection coefficient and the transmission coefficient:

suppose that

The reflection coefficient Γ may be expressed as:

moreover, | Γ | < 1;

from the transmission line theory, the following conclusions are drawn:

T＝e^-γd

where γ is the propagation constant, λ₀Is the operating wavelength, λ, of the electromagnetic wave_cIs the cut-off wavelength, ∈_rIs the complex dielectric constant, mu, of the sample to be measured_rIs the complex permeability of the material to be measured, Z and Z_rExpressed as the characteristic impedance of the standard rectangular waveguide and the sample region, respectively; obtaining the reflection coefficient gamma and the complex dielectric constant epsilon_rComplex magnetic permeability mu_rThe relationship between them is as follows:

obtaining a complex dielectric constant ε_rComplex magnetic permeability mu_rAnd loss tangent are expressed as follows:

wherein λ_gIs the waveguide wavelength.

Further, the electromagnetic parameter measuring method further comprises a compensation step, and the compensation step comprises the following steps:

outputting a third electromagnetic wave, wherein the fourth electromagnetic wave is obtained after the third electromagnetic wave penetrates through a filling medium and air;

receiving the fourth electromagnetic wave, and acquiring S parameters of air according to the third electromagnetic wave and the fourth electromagnetic wave;

obtaining the dielectric constant epsilon 'of the filling medium according to the S parameter of the air'_l；

According to the dielectric constant epsilon 'of the filling medium'_lAnd compensating the electromagnetic parameters of the sample to be tested to obtain the compensated electromagnetic parameters.

Further, the dielectric constant epsilon 'of the filling medium is obtained according to the S parameter of the air'_lThe method comprises the following steps:

acquiring the dielectric constant and loss tangent of air;

according to the dielectric constant and the loss tangent of the air and the electromagnetic parameters of the air obtained by calculation, the dielectric constant epsilon 'of the medium is reversely deduced'_l；

Wherein the dielectric constant ε of air_r1.0006, the loss tangent tan θ of air is 0.

The invention has the beneficial effects that: the electromagnetic parameter measuring system provided by the invention can be used for testing the electromagnetic parameters of the flexible material and/or the sheet material, can be used for simultaneously measuring various electromagnetic parameters, and improves the measuring efficiency.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description is made on the drawings of the embodiments of the present invention or the related technical solutions in the prior art, and it should be understood that the drawings in the following description are only for convenience and clarity of describing some embodiments in the technical solutions of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a diagram of a system for measuring electromagnetic parameters according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of an electromagnetic parameter measurement system according to an embodiment of the present invention;

FIG. 3 is a block diagram of the steps of the compensation algorithm in an embodiment of the present invention;

FIG. 4 is a voltage standing wave ratio between a standard rectangular waveguide and a filled rectangular waveguide in an embodiment of the invention;

FIG. 5 is a schematic diagram of the reflection and transmission of electromagnetic waves in the embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention. The step numbers in the following embodiments are provided only for convenience of illustration, the order between the steps is not limited at all, and the execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

As shown in fig. 1 and fig. 2, the present embodiment provides an electromagnetic parameter measurement system, which includes a waveguide coaxial converter 1, a dielectric-filled waveguide 2, a standard rectangular waveguide 3, a waveguide spacer 4, a sample 5 to be tested, a filling medium 6, a waveguide flange 7, and a TRL calibration component, where the TRL calibration component includes a transmission line 8 and a reflection plate 9; the dielectric-filled waveguide may be a dielectric-filled rectangular waveguide or a dielectric-filled waveguide of other shapes, and in this embodiment, a dielectric-filled rectangular waveguide is adopted;

one end of the waveguide coaxial converter is connected with the vector network analyzer through a coaxial line, and the other end of the waveguide coaxial converter is directly connected with the standard rectangular waveguide through a flange plate;

the standard rectangular waveguide and the medium-filled rectangular waveguide are designed integrally, and a filling medium is inserted into the medium-filled rectangular waveguide section;

one end of the filling medium adopts a multi-section ladder structure to realize impedance matching, and the broadside size of the medium filling rectangular waveguide section is reduced, so that the waveguide cut-off frequency between the standard rectangular waveguide and the medium filling waveguide is the same;

the sample to be tested is fixed inside the waveguide gasket, and the waveguide gasket is fixed between the flanges of the dielectric-filled waveguide;

one end of the filling medium is directly contacted with a sample to be tested, so that the sample to be tested is fixed, and the sample is prevented from falling off, deforming and the like.

In the present embodiment, the waveguide coaxial converter is connected to the vector network analyzer through the coaxial line, and converts the transmission mode of the electromagnetic wave into TE₁₀Mode(s). Using more than one waveguide between a standard rectangular waveguide and a dielectric-filled rectangular waveguideThe stepped structure realizes impedance matching between the two regions, and the value of the voltage standing wave ratio of the stepped structure in the whole frequency band is less than 1.07, as shown in fig. 4. At the beginning of each measurement experiment, the measurement system is calibrated using the TRL calibration piece. In the measuring process, the thickness of the sample 5 to be tested is consistent with that of the waveguide gasket 4; therefore, after each part in the system is fixed by a tool such as a bolt or a powerful clamp, the filling medium 3 is in direct contact with the sample 4, deformation of the flexible material or/and the extremely thin material can be prevented, and finally, electromagnetic parameters such as the complex dielectric constant, the complex permeability and the loss tangent of the material to be measured can be calculated through the collected parameters of the amplitude and the phase of the electromagnetic wave.

The TRL calibration piece calibrates the measurement system by:

taking a double port as an example, the method corresponds to a 1.2 port of a vector network analyzer and comprises the following specific steps:

a. the assembly of the measurement system is completed, but the reflector plate 9 is first placed in the position of the waveguide gasket and the sample, fixed between the two waveguide flanges, and the TRL calibration procedure of the vector network analyzer is clicked.

b. And (b) taking down the reflecting plate 9 in the step (a), replacing the reflecting plate 9 with a transmission Line 8, placing between the two waveguide flanges, fixing, and clicking a Line 1 key on the vector network analyzer to finish L.

c. And (c) taking down the transmission line 6 in the step (b), directly communicating the transmission line with the two waveguide flanges and fixing the transmission line, and clicking a Through key on the vector network analyzer to finish T.

The transmission line 8 and the reflection plate 9 are only used in the TRL calibration process before each experiment.

Based on the electromagnetic parameter measurement system, the embodiment further provides an electromagnetic parameter measurement method, which is used for measuring the electromagnetic parameters of the dielectric material, such as complex dielectric constant, complex permeability, loss tangent and the like. The method comprises the following specific steps:

in this embodiment, a transmission reflection method is used to measure the electromagnetic parameters of the sample to be tested. Compared with other testing methods, the transmission reflection method has the advantages of broadband measurement, capability of simultaneously measuring various electromagnetic parameters and the like. According to the method, a sample to be tested is placed in a transmission line system, the system can be regarded as a two-port network according to a microwave network analysis theory and a transmission line theory, as shown in figure 5, electromagnetic waves meet the sample to be tested in the transmission process and are reflected and transmitted, and the process is necessarily accompanied with energy attenuation and phase shift. The electromagnetic parameters of the sample to be detected can be calculated by the collected S parameters, and the S parameters have the following relations with the reflection coefficient and the transmission coefficient:

suppose that

The reflection coefficient Γ may be expressed as:

and, | Γ | < 1.

From the transmission line theory, the following conclusions can be drawn:

T＝e^-γd (5)

where γ is the propagation constant, λ₀Is the operating wavelength, λ, of the electromagnetic wave_cIs the cut-off wavelength, ∈_rIs the complex dielectric constant, mu, of the sample to be measured_rIs the complex permeability of the material to be measured, Z and Z_rExpressed as the characteristic impedance of the rectangular waveguide and the sample region, respectively. Therefore, Γ, ε can be obtained_rAnd mu_rThe relationship between

Finally, the calculations for complex permittivity, complex permeability and loss tangent can be derived:

wherein λ_gIs the waveguide wavelength.

As can be seen from the above calculation equations (11) and (12), the complex permittivity ε of the sample to be measured_rAnd the dielectric constant epsilon of the filling medium on both sides_lThere is a direct connection. According to the known electromagnetic wave theory, the complex dielectric constant of the same dielectric material changes with the change of frequency, so that the same fixed value cannot be used for calculation when the dielectric constant of the material to be measured is calculated. Therefore, the present embodiment proposes the following compensation algorithm, the steps of which are shown in fig. 3:

(1) firstly, calibrating a test system;

(2) the measurement system is used for testing the electromagnetic parameters of the air, because the dielectric constant of the air is less changed based on different frequencies;

(3) calculating electromagnetic parameters such as reflection coefficient and transmission coefficient of air by using calculation formulas (1) to (14);

(4) according to the calculated electromagnetic parameters of the air and according to the dielectric constant and loss tangent epsilon of the air_r1.0006, the dielectric constant ε 'of the filling medium in the dielectric-filled waveguide is inversely deduced from equations (11) to (12) with tan θ ═ 0 as a reference'_lDielectric constant ε'_lIs a complex number and varies with frequency;

(5) testing the material to be tested by using the waveguide gasket which is the same as that used for measuring the air electromagnetic parameters;

(6) ε 'of the filling Medium according to (4)'_lAnd (5) calculating the complex dielectric constant of the material to be tested after compensation by measuring the obtained S parameter.

In summary, compared with the prior art, the electromagnetic parameter measuring method of the embodiment has the following beneficial effects:

(1) the present embodiments enable testing of electromagnetic parameters of flexible and/or sheet materials using transmission reflection methods.

(2) The embodiment can realize the compensation of the dielectric constant of the sample, and obviously improves the accuracy of the measurement result.

In the foregoing description of the specification, reference to the description of "one embodiment/example," "another embodiment/example," or "certain embodiments/examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.