Horizontal double-ball quasi-optical cavity testing device for measuring electromagnetic performance of thin film material

Abstract

A horizontal double-ball quasi-optical cavity testing device for measuring the electromagnetic performance of a thin film material relates to the field of electromagnetic characteristic parameter testing, in particular to a quasi-optical cavity method testing system, and comprises a vector network analyzer (1), a frequency doubling module (2), a waveguide (3), a quasi-optical cavity (4), a sample clamp (5), a bidirectional transmission screw rod (6), a shielding frame (7), a displacement platform (8), a base (9) and a supporting block (10). The quasi-optical cavity (4) is of a double-spherical-cavity structure, is connected with the vector network analyzer (1) in a horizontal manner, and tests a sample by utilizing a resonance method; the sample clamp (5) adjusts the position of the sample by using a displacement platform (8); the shielding frame (7) can restrain miscellaneous molds, and the restraining effect is adjusted through the two-way transmission lead screw (6). The device has the advantages that the double-ball-cavity sensitivity is high, and the device is suitable for thin-film material testing; the horizontal structure is beneficial to connection of the vector network analyzer and the quasi-optical cavity; the double-ball cavity can measure the electromagnetic performance of the thin film material according to different odd and even modes.

Description

Technical Field

[0001] The invention discloses a horizontal double-ball quasi-optical cavity testing device for measuring the electromagnetic properties of thin film materials, and relates to the field of electromagnetic characteristic parameter testing, in particular to a quasi-optical cavity method testing system. Background Art

[0002] At present, the electromagnetic parameter testing of thin film materials faces huge challenges. The main problems are: 1. The thickness of thin film materials is extremely small, usually in the micron range. Therefore, when using microwave method to measure, the disturbance of thin film materials to electromagnetic field is small, and the sensitivity of measuring instruments is extremely high. 2. Thin film materials are easy to bend, and it is difficult to keep them flat during testing, which has a great impact on the test. The above problems show that the use of network parameter testing methods such as waveguides and coaxial lines to test thin film materials requires extremely high measurement accuracy of vector network analysis, otherwise it is insensitive to changes caused by thin film materials. Although the resonance method such as quasi-optical cavity has high sensitivity to thin film materials, the film itself is easy to bend, resulting in uneven surface of the material, which has a great impact on the test results. At present, the quasi-optical cavity method usually includes two methods: single spherical cavity and double spherical cavity. Among them, the single spherical cavity has attracted the attention of scholars because of its simple test system, convenient operation and high quality factor. Among them, the master's degree theses entitled "Research on High-precision Test Technology of Dielectric Properties of Quasi-optical Cavity Method" and "Research on Low-temperature Test Technology of Material Dielectric Parameters of Quasi-optical Cavity Method" both introduce the test principle and method of single spherical cavity in detail. However, for thin film materials with lower loss and thickness, the single spherical cavity method has certain limitations. Compared with the single spherical cavity, the double spherical cavity method has a better quality factor and can measure thin film materials with lower loss and lower thickness. However, the double spherical cavity method has high requirements for test operation. The sample needs to be placed in the middle of the double spherical cavity to obtain better test results. In addition, the thin film sample also has problems such as uneven surface. The design requirements for the double spherical cavity test system are also high. Therefore, the application of this method has certain limitations. Summary of the invention

[0003] The purpose of the present invention is to provide a horizontal double-ball quasi-optical cavity testing device for measuring the electromagnetic properties of thin film materials in view of the problems existing in microwave testing of thin film materials, which can improve the quality factor of the cavity and is suitable for testing the electromagnetic parameters of thin film materials. In addition, the device adopts a horizontal structure, and introduces a displacement platform and a bidirectional transmission screw to fine-tune the cavity structure, solving the structural symmetry problem of the double-ball cavity. In addition, due to the working mode characteristics of the double-ball cavity, the device can realize the measurement of the dielectric properties and magnetic permeability of thin film materials.

[0004] To achieve the above-mentioned purpose of the invention, the technical solution of the present invention is as follows:

[0005] A horizontal double-ball quasi-optical cavity test device for measuring the electromagnetic properties of thin film materials, as shown in the attached Figure 1As shown, it includes a vector network analyzer (1), a frequency doubling module (2), a waveguide (3), a quasi-optical cavity (4), a sample fixture (5), a bidirectional transmission screw (6), a shielding frame (7), a displacement platform (8), a base (9) and a support block (10). The quasi-optical cavity (4) is a double spherical mirror structure with mirror distribution, and the side surface is fixed to the base (9), so that the center line of the two spherical mirrors is parallel to the base (9); the vector network analyzer (1) is connected to the frequency doubling module (2), and the frequency doubling module (2) is connected to the quasi-optical cavity (4) through the waveguide (3), so that the quasi-optical cavity (4) excites a Gaussian beam for cavity resonance; the bottom of the sample fixture (5) is fixed to the displacement platform (8), and the displacement platform (8) is fixed to the base (9), so that the distance from the thin film sample to the spherical mirror can be fine-tuned according to the thickness of the sample, the purpose of which is to ensure that the film is always placed in the middle of the two cavities to achieve the best test effect; as shown in the attached Figure 2 As shown, a support block (10) is also fixed to the side of the quasi-optical cavity (4), and the support block (10) is fixed to the bidirectional transmission screw (6). The bidirectional transmission screw (6) is equipped with a shielding frame (7) with mirror distribution. A through hole is opened in the middle of the shielding frame (7) to ensure the passage of the Gaussian beam, and an absorbent is coated on the side of the shielding frame (7) close to the quasi-optical cavity (4) to absorb stray modes other than the Gaussian beam. The sample fixture (5) fixes the thin film sample with two annular sample clamps to ensure that its surface is flat. When the Gaussian beam passes through the surface of the film, the resonance mode of the quasi-optical cavity (4) is changed, and the electromagnetic parameters of the film can be calculated using the perturbation method.

[0006] As a preferred method, Figure 3 As shown, the test device adopts a double spherical mirror structure, which has higher test sensitivity than a single spherical mirror and is suitable for electromagnetic parameter testing of low electromagnetic disturbance materials such as thin films.

[0007] As a preferred method, Figure 4 As shown, the sample fixture (5) comprises a film (11), two annular sample clamps (12) and (13), a sample pressing plate (14) and a fixture base (15). The inner radius of the sample clamps (12) and (13) should be greater than twice the radius of the Gaussian beam waist, and the size of the film sample (11) should at least cover the entire inner circle of the sample clamp; the fixture base (15) is fixed to the base (9), and after the sample clamps (12) and (13) have fixed the film (11), they can be fixed to the fixture base (15) by the sample pressing plate (14).

[0008] As a preferred method, Figure 5As shown, the sample clamps (12) and (13) fix the film (11) through the sample loading platform (16). First, a cylinder protrudes from the surface of the sample loading platform (16), and its size just fills the inner ring of the sample clamp. The sample clamp (13) is placed on the sample loading platform (16), so that the inner ring of the sample clamp (13) is filled. Then, the film sample (11) is placed on the surface of the sample loading platform (16) and the sample clamp (13). Finally, the sample clamp (12) and the sample clamp (13) are fixed and the sample loading platform (16) is removed. This method can ensure that the film material is fixed flatly in the sample clamps (12) and (13).

[0009] As a preferred embodiment, the position of the thin film sample can be fine-tuned by the displacement platform (8) and adjusted according to the test data of the vector network analyzer 1. When the disturbance of the sample position to the odd-mode resonant frequency is the largest, it indicates that the sample is in the middle of the double spherical cavity.

[0010] As a preferred method, before installing the thin film sample, the distance between the shielding frame (7) and the quasi-optical cavity (4) is synchronously adjusted using a bidirectional transmission screw (6), so that the heterogeneous mode suppression efficiency of the double-spherical cavity Gaussian beam can be synchronously regulated, thereby simplifying the test operation.

[0011] As a preferred embodiment, the double-spherical quasi-optical cavity adopts a horizontal structure, which facilitates the connection between the measuring instrument and the cavity and ensures the structural symmetry of the double-spherical quasi-optical cavity.

[0012] As a preferred method, the working mode of the double-spherical quasi-optical cavity is TE00n (n is a positive integer). When n is an odd number, the electric field is the strongest in the middle of the double-spherical cavity, which can realize the measurement of the dielectric properties of the thin film; when n is an even number, the magnetic field is the strongest in the middle of the double-spherical cavity, which can realize the measurement of the magnetic permeability of the thin film. Therefore, the double-spherical cavity can be used to realize the dielectric and magnetic permeability tests of thin film samples.

[0013] The horizontal double-ball quasi-optical cavity testing device for measuring the electromagnetic properties of thin film materials provided by the present invention has the following characteristics and beneficial effects:

[0014] 1. The double spherical mirror quasi-optical cavity has a higher quality factor than the single spherical mirror, so the test sensitivity is higher and it can measure thin film samples with lower loss and thinner thickness;

[0015] 2. The double-ball quasi-optical cavity test device adopts a horizontal structure, which is conducive to connecting the measuring instrument with the quasi-optical cavity through a waveguide. In addition, the introduction of the displacement platform (8) and the bidirectional transmission screw (6) also ensures the structural symmetry of the double-ball quasi-optical cavity test device and simplifies the test operation;

[0016] 3. The double-sphere quasi-optical cavity can measure the dielectric properties and magnetic permeability of thin film materials according to the difference between odd and even modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Attached Figure 1 The schematic diagram of the structure of a horizontal double-ball quasi-optical cavity test device for measuring the electromagnetic properties of thin film materials is shown in the figure. Figure 2 The installation diagram of the double-ball quasi-optical cavity shielding frame is shown in Figure 2. Figure 3 Schematic diagram of the double-ball quasi-optical cavity test material; Figure 4 is a schematic diagram of the structure of the sample fixture; Figure 5 Schematic diagram of film installation.

[0018] Among them, (1) is a vector network analyzer, (2) is a frequency doubling module, (3) is a waveguide, (4) is a quasi-optical cavity, (5) is a sample fixture, (6) is a bidirectional transmission screw, (7) is a shielding frame, (8) is a displacement platform, (9) is a base, (10) is a support block, (11) is a thin film sample, (12) and (13) are sample clamps, (14) is a sample pressing plate, (15) is a fixture base, and (16) is a sample loading table. DETAILED DESCRIPTION

[0019] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0020] A horizontal double-ball quasi-optical cavity test device for measuring the electromagnetic properties of thin film materials, as shown in the attached Figure 1 As shown, it includes a vector network analyzer (1), a frequency doubling module (2), a waveguide (3), a quasi-optical cavity (4), a sample fixture (5), a bidirectional transmission screw (6), a shielding frame (7), a displacement platform (8), a base (9) and a support block (10). The quasi-optical cavity (4) is a double spherical mirror structure with mirror distribution, and the side surface is fixed to the base (9), so that the center line of the two spherical mirrors is parallel to the base (9); the vector network analyzer (1) is connected to the frequency doubling module (2), and the frequency doubling module (2) is connected to the quasi-optical cavity (4) through the waveguide (3), so that the quasi-optical cavity (4) excites a Gaussian beam for cavity resonance; the bottom of the sample fixture (5) is fixed to the displacement platform (8), and the displacement platform (8) is fixed to the base (9), so that the distance from the thin film sample to the spherical mirror can be fine-tuned according to the thickness of the sample, the purpose of which is to ensure that the film is always placed in the middle of the two cavities to achieve the best test effect; as shown in the attached Figure 2As shown, a support block (10) is also fixed to the side of the quasi-optical cavity (4), and the support block (10) is fixed to the bidirectional transmission screw (6). The bidirectional transmission screw (6) is equipped with a shielding frame (7) with mirror distribution. A through hole is opened in the middle of the shielding frame (7) to ensure the passage of the Gaussian beam, and an absorbent is coated on the side of the shielding frame (7) close to the quasi-optical cavity (4) to absorb stray modes other than the Gaussian beam. The sample fixture (5) fixes the thin film sample with two annular sample clamps to ensure that its surface is flat. When the Gaussian beam passes through the surface of the film, the resonance mode of the quasi-optical cavity (4) is changed, and the electromagnetic parameters of the film can be calculated using the perturbation method.

[0021] Furthermore, as attached Figure 4 As shown, the sample holder (5) comprises a film (11), two annular sample holders (12) and (13), a sample pressing plate (14) and a holder base (15). The inner radius of the sample holders (12) and (13) should be greater than twice the radius of the Gaussian beam waist, and the size of the film sample (11) should at least cover the entire inner circle of the sample holder.

[0022] Furthermore, a horizontal double-ball quasi-optical cavity testing device for measuring the electromagnetic properties of thin film materials, and a method for testing the electromagnetic parameters of thin film materials is as follows:

[0023] 1. Press the attachment Figure 1 The test system is built with the structure shown;

[0024] 2. Before testing, the film material is not installed and the main mode (TEM) is measured using a vector network analyzer. 00n , n is a positive integer), i.e., cavity data. In addition, a bidirectional transmission screw (6) is used to synchronously adjust the distance between the shielding frame (7) and the quasi-optical cavity (4) to reduce the interference of the stray mode on the main mode;

[0025] 3. Install the film sample. The installation method is as shown in the attached Figure 5 As shown in the figure, firstly, the sample holder (13) is placed on the sample loading platform (16), then the film sample (11) is placed on the surface of the sample loading platform (16) and the sample holder (13), then the sample holder (12) and the sample holder (13) are fixed and the sample loading platform (16) is removed, and finally, the sample holder with the film installed is pressed against the attached Figure 4 The method shown is mounted on a fixture base (15) and secured by a sample press plate (14);

[0026] 4. Adjust the film position. First, adjust the position of the sample fixture (5) by eye so that the film is roughly in the middle of the two cavities. Then adjust the position of the sample fixture (5) left and right and observe the panel data of the vector network analyzer. When the deviation between the resonance peak of the odd mode and the cavity data is the largest, it indicates that the sample is in the middle position. At this time, the resonance frequency and quality factor after loading the sample can be tested.

[0027] 5. Substituting the cavity data and the resonance parameters after loading the sample into the perturbation method formula, the electromagnetic parameters of the film can be obtained;

[0028] 6. For odd-numbered modes, the mode offset caused by the dielectric constant is much larger than the magnetic permeability, so the dielectric constant of the film can be measured using the odd-numbered mode; for even-numbered modes, the mode offset caused by the magnetic permeability is much larger than the dielectric constant, so the magnetic permeability of the film can be measured using the even-numbered mode.

[0029] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention and should still be covered by the claims of the present invention.

Claims

1. A horizontal double-ball quasi-optical cavity test device for measuring the electromagnetic properties of thin film materials, comprising: A vector network analyzer (1), a frequency doubling module (2), a waveguide (3), a quasi-optical cavity (4), a sample fixture (5), a bidirectional transmission screw (6), a shielding frame (7), a displacement platform (8), a base (9) and a support block (10); wherein the quasi-optical cavity (4) is a double spherical mirror structure with mirror distribution, and the side surface is fixed to the base (9) so that the center line of the two spherical mirrors is parallel to the base (9); the vector network analyzer (1) is connected to the frequency doubling module (2), and the frequency doubling module (2) is connected to the quasi-optical cavity (4) through the waveguide (3), so that the quasi-optical cavity (4) excites a Gaussian beam for cavity resonance; the bottom of the sample fixture (5) is connected to the position The displacement platform (8) is fixed, and the displacement platform (8) is fixed to the base (9); a support block (10) is also fixed to the side of the quasi-optical cavity (4), and the support block (10) is fixed to the bidirectional transmission screw (6), and the bidirectional transmission screw (6) is installed with a shielding frame (7) with mirror distribution; a through hole is opened in the middle of the shielding frame (7) to ensure the passage of the Gaussian beam, and the shielding frame (7) is coated with an absorbent on one side close to the quasi-optical cavity (4); the sample fixture (5) fixes the thin film sample with two annular sample clamps to ensure that its surface is flat; when the Gaussian beam passes through the surface of the film, it causes the resonance mode of the quasi-optical cavity (4) to change, and the electromagnetic parameters of the film can be calculated using the perturbation method.

2. The horizontal double-ball quasi-optical cavity testing device for measuring the electromagnetic properties of thin film materials according to claim 1, characterized in that: The test device adopts a double spherical mirror structure.

3. The horizontal double-ball quasi-optical cavity testing device for measuring the electromagnetic properties of thin film materials according to claim 1, characterized in that: The sample holder (5) comprises two annular sample holders, the inner circle radius of which should be greater than twice the beam waist radius of the Gaussian beam, and the size of the thin film sample should at least cover the entire inner circle of the sample holder.

4. The horizontal double-ball quasi-optical cavity test device for measuring the electromagnetic properties of thin film materials according to claim 1, characterized in that: The position of the thin film sample can be fine-tuned via a displacement platform (8) and adjusted according to test data from a vector network analyzer (1).

5. The horizontal double-ball quasi-optical cavity test device for measuring the electromagnetic properties of thin film materials according to claim 1, characterized in that Before installing the film sample, the distance between the shielding frame (7) and the quasi-optical cavity (4) is synchronously adjusted using a bidirectional transmission screw (6), so that the heterogeneous mode suppression efficiency of the double-spherical cavity Gaussian beam can be synchronously regulated, thereby simplifying the test operation.

6. The horizontal double-ball quasi-optical cavity testing device for measuring the electromagnetic properties of thin film materials according to claim 1, characterized in that: The double-ball quasi-optical cavity adopts a horizontal structure, which is convenient for connecting the measuring instrument with the cavity.

7. The horizontal double-ball quasi-optical cavity testing device for measuring electromagnetic properties of thin film materials according to claim 1, characterized in that: The working mode of the double-sphere quasi-optical cavity is TE 00n mode, n is a positive integer; when n is an odd number, the electric field is the strongest in the middle of the double spherical cavity, which can be used to measure the dielectric properties of the thin film; when n is an even number, the magnetic field is the strongest in the middle of the double spherical cavity, which can be used to measure the magnetic permeability of the thin film. Therefore, the double spherical cavity can be used to test the dielectric and magnetic permeability of thin film samples.

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