An anisotropic dielectric constant-based measurement system and measurement method

Abstract

The present invention discloses a measurement system and a measurement method based on anisotropic dielectric constant. The measurement system includes a first orthogonal mode coupler, a second orthogonal mode coupler and a sample; the common ports of the first orthogonal mode coupler and the second orthogonal mode coupler are respectively connected to both ends of the gasket through square waveguides; two orthogonally polarized electric field modes are respectively input into the coupling port and the through port of the first orthogonal mode coupler, the coupling port and the through port of the first orthogonal mode coupler are excited, and the first orthogonal mode coupler couples the two orthogonally polarized electric field modes into the square waveguide; when the electromagnetic wave is transmitted between the two square waveguides, multiple reflection and transmission phenomena will occur at the interface of the sample; the second orthogonal mode coupler separates the two orthogonally polarized electric field modes and outputs them through the coupling port and the through port respectively. The present invention can efficiently solve the test problems of measuring anisotropic materials by the transmission / reflection method.

Description

Technical Field

[0001] The present invention relates to the technical fields of microwaves, millimeter waves, anisotropic dielectric constant measurement, and transmission / reflection method, and particularly relates to a measurement system and method based on anisotropic dielectric constant measurement. Background Art

[0002] The dielectric constant is a physical parameter characterizing the dielectric or polarization properties of dielectric materials. Before designing circuits or systems based on various materials, it is very important to accurately master the dielectric constant and loss characteristics of these materials.

[0003] The transmission / reflection method is a technical method based on transmission line theory and microwave devices, which can measure electromagnetic characteristics such as the relative dielectric constant, relative permeability, and loss tangent of dielectric materials within the working frequency band of the transmission line. The commonly used transmission line is a rectangular waveguide. During the measurement process, the dielectric to be measured needs to be fixed in a gasket, and then the gasket is connected to the flange of the rectangular waveguide to achieve the purpose of inserting the sample into the interior of the rectangular waveguide. During the actual measurement of the relative dielectric constant, the mechanism is that the electric field interacts with the dielectric material, resulting in the direction of the measured relative dielectric constant being the same as the direction of the electric field. Therefore, the rectangular waveguide usually operates in the main mode frequency band to ensure that the electric field direction inside the rectangular waveguide is single and avoid the interference of high-order modes, which affects the accuracy of the final measurement result.

[0004] According to electromagnetic field theory, when an electromagnetic wave propagates inside a rectangular waveguide, numerous reflection and transmission phenomena will occur at the interface of the sample. The relative dielectric constant and relative permeability of the dielectric filled inside the rectangular waveguide are ε l and μ l , and c is the speed of light.

[0005] Assume that the reflection coefficient at the first reflection of the electromagnetic wave is Г, the transmission coefficient between two interfaces is T, and the entire measurement system is regarded as a two-port microwave network. Then, based on mathematics and microwave theory, the following relationship can be deduced between Г, T, and the scattering parameters:

[0006]

[0007]

[0008] If the variable X is defined to satisfy the following formula:

[0009]

[0010] Then the following relationship is satisfied between the reflection coefficient Г and X:

[0011]

[0012] That is, the reflection coefficient Г can be directly calculated from the scattering parameters. Since there must be energy loss during the reflection of electromagnetic waves, the reflection coefficient Г should satisfy the condition: Γ≤1, from which the sign selection in the above formula can be determined.

[0013] In addition, according to the transmission line theory and the electromagnetic field theory, the following relationships are satisfied among the various parameters of electromagnetic waves:

[0014] T = e -γd (5)

[0015]

[0016]

[0017]

[0018]

[0019] where γ is the propagation constant of electromagnetic waves inside the waveguide, d is the thickness of the sample, λ 0 is the working wavelength of electromagnetic waves, λ c is the cut-off wavelength of the rectangular waveguide, ε r is the relative complex permittivity of the dielectric material to be measured, μ r is the relative complex permeability of the dielectric material to be measured, Z and Z r represent the characteristic impedances of the rectangular waveguide and the dielectric sample section, respectively.

[0020] Combining the above formulas, the relational expressions among the reflection coefficient Г, the relative complex permittivity ε r and the relative complex permeability μ r can be derived:

[0021]

[0022] The relative complex permeability, relative complex permittivity and loss tangent of the sample are respectively derived as:

[0023]

[0024]

[0025]

[0026] Among them, Λ can be calculated by the following formula:

[0027]

[0028] Assuming that λ g is the waveguide wavelength of the rectangular waveguide, then we can get:

[0029]

[0030] The plus or minus sign of Equation (14) can be determined from Equation (15).

[0031] The transmission / reflection method can deduce the electromagnetic properties of a sample, such as the relative complex permittivity, relative permeability, and loss tangent, from the scattering parameters of the collected sample. The transmission / reflection method of a rectangular waveguide usually only uses the fundamental mode of the rectangular waveguide for testing, so it can only measure the permittivity in one direction. Currently, there are few publicly available research results describing the application of the transmission / reflection method in measuring the anisotropic permittivity of materials.

[0032] Before measuring the electromagnetic properties of microwave materials, the entire measurement system must be calibrated to eliminate measurement errors caused by factors such as instruments and cables. The TRL calibration technique can calibrate the measurement systems of the transmission / reflection method and the free-space method. In the TRL calibration technique, all errors outside the reference planes of the two ports are regarded as error boxes characterized by the scattering matrix or the transmission matrix, and it is assumed that the two ends of the error box have the same characteristic impedance, so it can be regarded as a reciprocal microwave network. The TRL calibration technique can characterize the two error boxes through three connection methods, namely Thru (through), Reflect (reflection), and Line (delay line). Only by recording the scattering parameters of the "through" connection, "reflection" connection, and "delay line" connection can the calibration work of the measurement system be completed. As long as the transmission matrix of the error box is obtained, the transmission matrix of the area of the sample to be measured can be easily solved, and then its scattering matrix can be obtained to achieve the purpose of calibration. In the actual design, processing, and manufacturing process of the TRL calibration component, the "through" connection is generally a transmission line with a length of 0, so mainly reflectors and delay lines need to be processed. The reflector can be replaced by a metal plate with a high reflection coefficient; for a waveguide system, the length of the delay line generally takes a quarter of the waveguide wavelength corresponding to the center operating frequency.

[0033] In the prior art, there is a model-based optical measurement of a semiconductor structure with anisotropic permittivity. The present invention proposes a measurement system for a semiconductor structure with anisotropic permittivity, a method and system for performing an optical model-based measurement of a small-size semiconductor structure by using anisotropic characterization of the optical dispersion properties of one or more materials including the measured structure. This reduces the correlation among geometric parameters and results in improved measurement sensitivity, improved measurement accuracy, and increased measurement contrast among multiple measured materials. However, the method it uses is an optical method and cannot measure the anisotropic permittivity of semiconductor materials in the microwave frequency band, and does not have the advantage that the transmission / reflection method can measure the electromagnetic properties such as the relative permittivity, relative permeability, and loss tangent of dielectric materials within the operating frequency band of the transmission line.

[0034] In the prior art, there is a measuring device and method for the complex permittivity of thin-film materials based on the transmission-reflection method. When measuring, an uncoated thin film and a dielectric substrate coated with a thin film are respectively placed vertically in the middle of a microstrip line to obtain two sets of parameters. Then, based on the two sets of obtained data and combined with the transmission-reflection method, the effective permittivities of the uncoated thin film and the dielectric substrate coated with the thin film are deduced. Then, by determining the filling factor, the true permittivity of the thin-film material is separated from the effective permittivity. This invention has a wide test frequency band, a simple structure, strong repeatability, and high test accuracy in the GHz frequency band range. However, it cannot measure the anisotropic permittivity of materials by the transmission / reflection method, and has limitations in the test of materials.

[0035] In the prior art, there is a coaxial test fixture for the permittivity of materials by the transmission-reflection method and its manufacturing method. This invention proposes a coaxial test fixture for the permittivity of materials by the transmission-reflection method and its manufacturing method. Based on the traditional coaxial test fixture, the structure of the traditional coaxial test fixture is modified, and a coaxial fixture structure with an extended inner conductor is proposed, effectively improving the problem of inconvenient connection of the test fixture and improving the measurement accuracy. Similarly, it has the limitation that it cannot measure the anisotropic permittivity of the sample and can only measure the permittivity in a certain direction. Summary of the Invention

[0036] The purpose of the present invention is to provide a method to overcome the limitations of the traditional transmission / reflection method in measuring anisotropic permittivity and fill the gap in measuring the anisotropic permittivity of materials by the transmission / reflection method.

[0037] The purpose of the present invention is achieved by at least one of the following technical solutions.

[0038] An anisotropic permittivity measurement system includes a first orthogonal mode coupler, a second orthogonal mode coupler, and a sample;

[0039] Among them, the coupling ports and through ports of the first orthogonal mode coupler and the second orthogonal mode coupler are all connected to standard rectangular waveguides to ensure the connection characteristics between the orthogonal mode couplers and other devices;

[0040] The sample is placed on a gasket; the common ports of the first orthogonal mode coupler and the second orthogonal mode coupler are respectively connected to both ends of the gasket through square waveguides;

[0041] Two orthogonally polarized electric field modes are respectively input into the coupling port and through port of the first orthogonal mode coupler. The coupling port and through port of the first orthogonal mode coupler are excited, and the first orthogonal mode coupler couples the two orthogonally polarized electric field modes into the square waveguide;

[0042] When electromagnetic waves are transmitted inside a rectangular waveguide, multiple reflection and transmission phenomena will occur at the interface of the sample;

[0043] The second orthogonal mode coupler separates two orthogonally polarized electric field modes and outputs them through the coupling port and the through port respectively.

[0044] Furthermore, in the simulation process, the voltage standing wave ratios of the coupling port and the through port of the second orthogonal mode coupler are both lower than 1.07, and the isolation between TE 10 and TE 01 is lower than -63 dB in the range of 9.8 - 12 GHz. At this time, the second orthogonal mode coupler has extremely high isolation, and the two electric field modes output from the coupling port and the through port can be regarded as two independent modes, so as to ensure that the anisotropic dielectric constant measurement system can calculate the anisotropic dielectric constant of the sample according to the data collected from the coupling ports and through ports of the first orthogonal mode coupler and the second orthogonal mode coupler.

[0045] Furthermore, the through ports and coupling ports of the first orthogonal mode coupler and the second orthogonal mode coupler are all rectangular waveguides, aiming to ensure good connection characteristics between the orthogonal mode coupler and other components.

[0046] Furthermore, the transition section between the through ports and the common port of the first orthogonal mode coupler and the second orthogonal mode coupler adopts a stepped waveguide structure to improve the frequency band characteristics and reduce the reflection of electromagnetic waves.

[0047] An anisotropic dielectric constant measurement method based on the following steps:

[0048] S1. Install an anisotropic dielectric constant measurement system based on the transmission / reflection method;

[0049] S2. Calibrate the anisotropic dielectric constant measurement system based on the transmission / reflection method using three connection methods:

[0050] S3. System error calculation: Use the TRL calibration technique to determine the transmission matrix of the sample according to the scattering parameters obtained from the three connection methods in step S2;

[0051] S4. Sample testing: Insert a sample filled with anisotropic dielectric constant and record all the scattering parameters of the coupling ports and through ports of the first orthogonal mode coupler and the second orthogonal mode coupler;

[0052] S5. Complex dielectric constant calculation: Calculate the anisotropic complex dielectric constant of the sample according to the data calculated or recorded in step S3 and step S4 using the formula for measuring the dielectric constant by the transmission / reflection method.

[0053] Further, in step S2, calibrating the anisotropic dielectric constant measurement system based on the transmission / reflection method includes the following steps:

[0054] S2.1, Reflect connection: Fix a metal plate on the calibration planes of two rectangular waveguides, and save the scattering parameters of the coupling ports and the through ports of the first orthogonal mode coupler and the second orthogonal mode coupler;

[0055] S2.2, Line connection: Replace the metal plate with a rectangular waveguide with a length of a quarter waveguide wavelength on the calibration plane, and save the scattering parameters of the coupling ports and the through ports of the first orthogonal mode coupler and the second orthogonal mode coupler;

[0056] S2.3, Thru connection: Directly connect the two rectangular waveguides with a flange, and save the scattering parameters of the coupling ports and the through ports of the first orthogonal mode coupler and the second orthogonal mode coupler.

[0057] Further, the calibration plane of the rectangular waveguide connected to the common ports of the first orthogonal mode coupler and the second orthogonal mode coupler is the flange surface close to the sample.

[0058] Compared with the prior art, the advantages of the present invention are as follows:

[0059] It relates to the field of microwave and millimeter-wave dielectric constant testing, specifically an anisotropic dielectric constant testing technology based on the transmission / reflection method, which can efficiently solve the testing problems of measuring anisotropic materials by the transmission / reflection method. It fills the gap that most of the currently published research works use the resonant cavity method for measurement, and there are few research works on measuring the anisotropic dielectric constant of materials by the transmission / reflection method. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is a schematic diagram of the traditional transmission / reflection method based on a rectangular waveguide in the embodiment of the present invention;

[0061] Figure 2 is a schematic diagram of the reflection and transmission of electromagnetic waves in the embodiment of the present invention;

[0062] Figure 3 is a schematic diagram of the anisotropic dielectric constant measurement system in the embodiment of the present invention;

[0063] Figure 4 is a sectional view of the components and structure of the anisotropic dielectric constant measurement system in the embodiment of the present invention;

[0064] Figure 5 is a simulation model and an electric field distribution diagram of the orthogonal mode coupler in the HFSS software in the embodiment of the present invention;

[0065] Figure 6a It is a schematic diagram of the voltage standing wave ratio of the through port and the coupling port in the simulation result of the orthogonal mode coupler in the HFSS software in the embodiment of the present invention;

[0066] Figure 6b It is TE in the simulation result of the orthogonal mode coupler in the HFSS software in the embodiment of the present invention 10 and TE 01 isolation diagram;

[0067] Figure 7 It is the test flow chart of the anisotropic dielectric constant measurement system in each embodiment of the present invention. Specific Embodiments

[0068] The following further describes the specific embodiments of the present invention in detail with reference to the drawings and embodiments.

[0069] Embodiment 1:

[0070] As Figure 1 shown, it is a schematic diagram of the traditional transmission / reflection method based on a rectangular waveguide.

[0071] An anisotropic dielectric constant measurement system, such as Figure 3 and Figure 4 shown, includes a first orthogonal mode coupler, a second orthogonal mode coupler and a sample;

[0072] Among them, the coupling ports and the through ports of the first orthogonal mode coupler and the second orthogonal mode coupler are all connected to standard waveguides to ensure the connection characteristics between the orthogonal mode coupler and other devices;

[0073] The sample is placed on the gasket; the common ports of the first orthogonal mode coupler and the second orthogonal mode coupler are respectively connected to both ends of the gasket through square waveguides;

[0074] Two orthogonally polarized electric field modes are respectively input into the coupling port and the through port of the first orthogonal mode coupler. The coupling port and the through port of the first orthogonal mode coupler are excited, and the first orthogonal mode coupler couples the two orthogonally polarized electric field modes into the square waveguide;

[0075] As Figure 2 shown, when the electromagnetic wave propagates inside the rectangular waveguide, countless reflection and transmission phenomena will occur at the interface of the sample;

[0076] The second orthogonal mode coupler separates two orthogonally polarized electric field modes and outputs them respectively through the coupling port and the through port.

[0077] In this embodiment, the orthogonal mode coupler mainly has the following important reference indicators:

[0078] (1) Operating frequency and bandwidth: It refers to the frequency and frequency range at which the orthogonal mode coupler can operate normally.

[0079] (2) Return loss: Due to the sudden change in the shape of the transmission line in the orthogonal mode coupler, this will inevitably cause the reflection of electromagnetic waves, resulting in a large return loss. Therefore, a high-performance orthogonal mode coupler requires a low return loss. The lower the return loss, the smaller the loss of electromagnetic wave energy.

[0080] (3) Insertion loss: Insertion loss represents the ratio of the energy at the output port of the orthogonal mode coupler to the energy at the input port, which can characterize the quality of the circuit design and manufacturing of the orthogonal mode coupler.

[0081] (4) Isolation: The isolation between the ports of the orthogonal mode coupler refers to the degree to which a signal leaks from one port to other ports when input from one port. An orthogonal mode coupler with high isolation can avoid signal crosstalk and improve communication capabilities.

[0082] (5) Cross-polarization ratio: Since there are two polarization modes in the orthogonal mode coupler, the cross-polarization ratio can be used to characterize the correlation between these two modes.

[0083] The above five parameters are the main indicators for characterizing the quality of the orthogonal mode coupler.

[0084] As Figure 5 shown, it shows the simulation model and the electric field distribution map of the orthogonal mode coupler in the HFSS software. This model operates in the X band. The through ports and coupled ports of the first orthogonal mode coupler and the second orthogonal mode coupler are all standard rectangular waveguides WR90, aiming to ensure good connection characteristics between the first orthogonal mode coupler and the second orthogonal mode coupler and other components. In addition, for the convenience of manufacturing, the common port of the first orthogonal mode coupler and the second orthogonal mode coupler is a square waveguide with rounded corners; the transition section between the through port and the common port adopts a stepped waveguide structure to improve the frequency band characteristics and reduce the reflection of electromagnetic waves. As Figure 6a and Figure 6b shown, it shows the results of the voltage standing wave ratio of the coupled port and the through port. It can be seen from this that the voltage standing wave ratios of both ports are lower than 1.07, while the isolation of TE 10 and TE 01 is lower than -63 dB in the range of 9.8 - 12 GHz, indicating that the second orthogonal mode coupler has extremely high isolation. The two electric field modes output from the coupled port and the through port can be regarded as two independent modes, thus ensuring that the anisotropic dielectric constant measurement system can calculate the anisotropic dielectric constant of the sample based on the data collected from the coupled port and the through port of the first orthogonal mode coupler and the second orthogonal mode coupler.

[0085] Based on the simulation results, the orthogonal mode coupler adopted in this embodiment has excellent performance and meets the expectations.

[0086] Embodiment 2:

[0087] A method for measuring anisotropic permittivity, as Figure 7 shown, includes the following steps:

[0088] S1. Install an anisotropic permittivity measurement system based on the transmission / reflection method;

[0089] S2. Calibrate the anisotropic permittivity measurement system based on the transmission / reflection method using three connection methods, including the following steps:

[0090] S2.1 Reflect connection: Fix a metal plate on the calibration planes of two rectangular waveguides, and save the scattering parameters of the coupling ports and through ports of the first orthogonal mode coupler and the second orthogonal mode coupler; the calibration planes of the two rectangular waveguides are their flange faces close to the sample.

[0091] S2.2 Line connection: Replace the metal plate with a rectangular waveguide with a length of one-quarter waveguide wavelength on the calibration plane, and save the scattering parameters of the coupling ports and through ports of the first orthogonal mode coupler and the second orthogonal mode coupler;

[0092] S2.3 Thru connection: Directly connect the two rectangular waveguides with a flange, and save the scattering parameters of the coupling ports and through ports of the first orthogonal mode coupler and the second orthogonal mode coupler.

[0093] S3. System error calculation: Adopt the TRL calibration technique, and determine the transmission matrix of the sample according to the scattering parameters obtained by the three connection methods in step S2;

[0094] S4. Sample testing: Insert a sample filled with anisotropic permittivity, and record all the scattering parameters of the coupling ports and through ports of the first orthogonal mode coupler and the second orthogonal mode coupler;

[0095] S5. Complex permittivity calculation: According to the data calculated or recorded in step S3 and step S4, calculate the anisotropic complex permittivity of the sample using the formula for measuring permittivity by the transmission / reflection method.

[0096] Embodiment 3:

[0097] Compared with Embodiment 2, in this embodiment, in step S5, the transmission / reflection method is a technical method based on transmission line theory and microwave devices, which can measure electromagnetic characteristics such as relative permittivity, relative permeability, and loss tangent of dielectric materials within the working frequency band of the transmission line. The commonly used transmission line is a rectangular waveguide. During the measurement process, the dielectric to be measured needs to be fixed in a gasket, and then the gasket is connected to the flange of the rectangular waveguide, so as to achieve the purpose of inserting the sample into the interior of the rectangular waveguide. In the actual measurement process of the relative permittivity, the mechanism is that the electric field interacts with the dielectric material, resulting in the direction of the measured relative permittivity being the same as the direction of the electric field. Therefore, the rectangular waveguide usually operates in the main mode frequency band to ensure that the electric field direction inside the rectangular waveguide is single and avoid the interference of higher-order modes, which may affect the accuracy of the final measurement result.

[0098] According to the electromagnetic field theory, when an electromagnetic wave propagates inside a rectangular waveguide, numerous reflection and transmission phenomena will occur at the interface of the sample. The relative permittivity and relative permeability of the dielectric filled inside the rectangular waveguide are ε l and μ l , and c is the speed of light.

[0099] Assume that the reflection coefficient at the first reflection of the electromagnetic wave is Г, the transmission coefficient between two interfaces is T, and the entire measurement system is regarded as a two-port microwave network. Then, based on mathematics and microwave theory, it can be deduced that there is the following relationship between Г, T, and the scattering parameters:

[0100]

[0101]

[0102] If the variable X is defined to satisfy the following formula:

[0103]

[0104] Then the following relationship is satisfied between the reflection coefficient Г and X:

[0105]

[0106] That is, the reflection coefficient Г can be directly calculated from the scattering parameters. Since there must be energy loss during the reflection process of the electromagnetic wave, the reflection coefficient Г should satisfy the condition: Γ≤1, from which the sign selection in the above formula can be judged.

[0107] In addition, according to the transmission line theory and the electromagnetic field theory, the following relationship is satisfied among the various parameters of the electromagnetic wave:

[0108] T = e -γd (5)

[0109]

[0110]

[0111]

[0112]

[0113] where γ is the propagation constant of the electromagnetic wave inside the waveguide, d is the thickness of the sample, λ 0 is the operating wavelength of the electromagnetic wave, λ c is the cut-off wavelength of the rectangular waveguide, ε r is the relative complex permittivity of the dielectric material to be measured, μ r is the relative complex permeability of the dielectric material to be measured, Z and Z r represent the characteristic impedances of the rectangular waveguide and the dielectric sample section, respectively.

[0114] Combining the above equations, the relationship between the reflection coefficient Г, the relative complex permittivity ε r and the relative complex permeability μ r can be derived as follows:

[0115]

[0116] The relative complex permeability, relative complex permittivity and loss tangent of the sample are respectively derived as:

[0117]

[0118]

[0119]

[0120] where Λ can be calculated by the following formula:

[0121]

[0122] Assuming that λ g is the waveguide wavelength of the rectangular waveguide, then we can get:

[0123]

[0124] The plus or minus sign of Equation (14) can be determined by Equation (15).

[0125] The transmission / reflection method can derive the electromagnetic properties of a sample, such as the relative complex permittivity, relative permeability, and loss tangent, from the scattering parameters of the collected sample. The transmission / reflection method of a rectangular waveguide usually only uses the fundamental mode of the rectangular waveguide for testing, so it can only measure the permittivity in one direction. There are almost no publicly available research results describing the application of the transmission / reflection method in measuring the anisotropic permittivity of materials.

Claims

1. An anisotropic dielectric constant measurement system, characterized in that, it includes a first orthogonal mode coupler, a second orthogonal mode coupler and a sample; wherein, the coupling ports and the through ports of the first orthogonal mode coupler and the second orthogonal mode coupler are all connected to standard waveguides to ensure the connection characteristics between the orthogonal mode couplers and other devices; the sample is placed on a gasket; the common ports of the first orthogonal mode coupler and the second orthogonal mode coupler are respectively connected to both ends of the gasket through square waveguides; two orthogonally polarized electric field modes are respectively input into the coupling port and the through port of the first orthogonal mode coupler, the coupling port and the through port of the first orthogonal mode coupler are excited, and the first orthogonal mode coupler couples the two orthogonally polarized electric field modes into the square waveguide; when the electromagnetic wave propagates between the two square waveguides, multiple reflection and transmission phenomena will occur on the interface of the sample; the second orthogonal mode coupler separates to obtain two orthogonally polarized electric field modes and outputs them through the coupling port and the through port respectively.

2. The anisotropic dielectric constant measurement system according to claim 1, characterized in that, During the simulation, the voltage standing wave ratios of the coupled port and the through port of the second orthogonal mode coupler are both lower than 1.07, and the isolation of TE 10 and TE 01 is lower than -63 dB in the range of 9.8 - 12 GHz.

3. The anisotropic dielectric constant measurement system according to claim 1, characterized in that, the through ports and the coupling ports of the first orthogonal mode coupler and the second orthogonal mode coupler are both rectangular waveguides.

4. The anisotropic dielectric constant measurement system according to claim 1, characterized in that, the transition section between the through ports and the common ports of the first orthogonal mode coupler and the second orthogonal mode coupler adopts a stepped waveguide structure.

5. The measurement method of the anisotropic dielectric constant measurement system according to any one of claims 1 to 4, characterized in that, it includes the following steps: S1. Install the anisotropic dielectric constant measurement system based on the transmission / reflection method; S2. Calibrate the anisotropic dielectric constant measurement system based on the transmission / reflection method by using three connection methods: S3. System error calculation: Adopt the TRL calibration technique, and determine the transmission matrix of the sample according to the scattering parameters obtained by the three connection methods in step S2; S4. Sample test: Insert a sample filled with anisotropic dielectric constant, and record all the scattering parameters of the coupling ports and the through ports of the first orthogonal mode coupler and the second orthogonal mode coupler; S5. Complex dielectric constant calculation: According to the data obtained in step S3 and step S4, use the formula for measuring the dielectric constant by the transmission / reflection method to calculate the anisotropic complex dielectric constant of the sample; In step S2, calibrating the anisotropic dielectric constant measurement system based on the transmission / reflection method includes the following steps: S2.

1. Reflect connection; S2.

2. Line connection; S2.

3. Thru connection.

6. The anisotropic dielectric constant measurement method according to claim 5, characterized in that, in step S2.1, for the Reflect connection: Fix a metal plate on the calibration planes of the two square waveguides, and save the scattering parameters of the coupling ports and the through ports of the first orthogonal mode coupler and the second orthogonal mode coupler.

7. A method for measuring anisotropic dielectric constant according to claim 6, characterized in that, the calibration plane of the square waveguide connected to the common port of the first orthogonal mode coupler and the second orthogonal mode coupler is the flange surface close to the sample.

8. A method for measuring anisotropic dielectric constant according to claim 7, characterized in that, in step S2.2, Line connection: replace the metal plate with a square waveguide with a length of one-quarter waveguide wavelength on the calibration plane, and save the scattering parameters of the coupling ports and the through ports of the first orthogonal mode coupler and the second orthogonal mode coupler.

9. A method for measuring anisotropic dielectric constant according to claim 8, characterized in that, in step S2.3, Thru connection: directly connect the two square waveguides with a flange, and save the scattering parameters of the coupling ports and the through ports of the first orthogonal mode coupler and the second orthogonal mode coupler.

Images