A dielectric constant testing device based on electric field focusing resonant cavity

Abstract

This invention provides a dielectric constant test device based on an electric field converging resonant cavity, belonging to the technical field of electromagnetic parameter testing for microwave and millimeter-wave materials. By designing ridges within the cavity, the device increases the compression strength of the electric field within the cavity, significantly improving the sensitivity and quality factor of the resonant cavity. This effectively enhances the accuracy and precision of dielectric constant testing of nanometer-sized materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave and millimeter wave material electromagnetic parameter testing, and in particular relates to a dielectric constant testing device based on electric field convergence resonance. Background Art

[0002] Micron- and even nanometer-scale materials are widely used in various fields, such as high-frequency circuit substrates, wave-absorbing materials, and currently popular smart wearable devices. Accurately determining the dielectric properties of these materials will greatly facilitate their precise application.

[0003] Professor Gao Chong's team at the University of Electronic Science and Technology of China, in patent publication number CN114966225 A, disclosed a single-fiber dielectric constant test device based on a single-ridged semi-cylindrical cavity. This device constructs a single-ridged semi-cylindrical resonant cavity and designs a lofted gap. This saves cavity structure and reduces processing costs while ensuring effective testing. However, subsequent research revealed that the device, due to limitations in sensitivity and quality factor, could only test fiber materials with diameters in the micrometer range. Once the diameter of the fine material reaches the nanometer level, the test accuracy falls short, making it impossible to accurately measure the dielectric constant. Summary of the Invention

[0004] To address the challenges presented by the prior art, the present invention aims to provide a dielectric constant measurement device based on an electric field converging resonant cavity. This device utilizes a design of ridges within the cavity to enhance the compressive strength of the electric field within the cavity, significantly improving the sensitivity and quality factor of the resonant cavity. This effectively enhances the accuracy and precision of dielectric constant measurements of nanometer-sized materials.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A dielectric constant testing device based on an electric field convergence resonant cavity, comprising a resonant cavity body 1, an upper cover plate 2, a side cover plate 3, and a coupling device; wherein the resonant cavity body 1 is a "U-shaped platform" as a whole, comprising two first and second side surfaces with "U"-shaped cross-sections and parallel to each other; the inner wall 1-1 of the resonant cavity body 1 is a semicircular arc, and a ridge 1-2 is provided at the lowest point of the center of the semicircular arc. The ridge consists of an upper and lower part; the vertical cross-section of the ridge is trapezoidal, the lower base of which is an arc with the same curvature as the inner wall of the resonant cavity body 1, and the upper base is a straight line and parallel to the upper cover plate; the horizontal length of the ridge is the same as the length of the resonant cavity body 1; the upper part 1-2-2 of the ridge and the lower part 1-2-1 are both made of metal materials, but the dielectric constant of the material of the upper part 1-2-2 is higher than the dielectric constant of the material of the lower part 1-2-1;

[0007] The side cover plate 3 includes a first cover plate and a second cover plate; the first cover plate is fixedly connected to the first side surface of the resonant cavity 1, the second cover plate is fixedly connected to the second side surface of the resonant cavity 1, and the upper cover plate is fixedly arranged on the top of the resonant cavity 1; a notch is provided at the center of the top edge of the first cover plate and the second cover plate;

[0008] The resonant cavity body 1, the upper cover plate 2 and the side cover plate 3 together form a semi-cylindrical resonant cavity, and the notches of the first cover plate and the second cover plate and the top of the ridge 1-2 together serve as a lofting channel;

[0009] The coupling device includes a coupling excitation device and a coupling receiving device. Coupling holes are provided on the first cover plate and the second cover plate. The two coupling holes are respectively located on different sides at both ends and are symmetrical about the central plane of the semi-cylinder. The coupling excitation device is placed in one coupling hole, and the coupling receiving device is placed in the other coupling hole.

[0010] Furthermore, the upper portion of the ridge is made of a high dielectric constant metal material, with a dielectric constant of 50-110, preferably 80.

[0011] Furthermore, the upper and lower parts of the spine are embedded and fixedly connected by built-in pins.

[0012] Furthermore, the top of the ridge does not contact the upper cover plate 2, and the distance between the two is preferably 0.2 mm.

[0013] Furthermore, the width of the top of the ridge is 0.1-0.4 mm, and the vertical height of the upper ridge is 1.4-2.5 mm.

[0014] Furthermore, the width of the top of the ridge is preferably 0.2 mm, and the vertical height of the upper ridge is preferably 1.7 mm.

[0015] Furthermore, the distance between the top of the ridge and the upper cover plate 2 is the same as the width of the top of the ridge, forming a test area with a square cross-section. If the area of ​​this area is too large, the compression strength of the electric field will be insufficient, affecting the test effect; if it is too small, it will affect the processing accuracy.

[0016] Furthermore, the inner wall of the semi-cylindrical resonant cavity and the surface of the lower half of the ridge are both silver-plated.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] For an ideal conductor, the electric field is fully reflected at the boundary between air and the conductor, and the field inside the conductor is zero. However, in reality, materials cannot achieve this effect. Therefore, the larger the dielectric constant of a metal material, the closer its conductivity is to that of an ideal conductor, and the less field enters the material, that is, the loss is small, which increases the reflected field, thereby improving the compressive strength of the field. Therefore, the present invention realizes the improvement of the compressive strength of the electric field in the cavity by using two different materials to realize the ridge at the center of the arc wall of the semi-cylindrical cavity, and using a high dielectric constant material for the upper half of the ridge. At the same time, based on perturbation theory, after the electric field strength in the test area is compressed, when the material to be tested is placed, the impact and disturbance on the field are greater, which greatly improves the sensitivity and quality factor of the resonant cavity compared to previous cavities. Moreover, the higher dielectric constant of the metal material will definitely increase its conductivity compared to silver, which will also improve the quality factor, thereby effectively improving the accuracy and precision of testing nano-scale fine materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structural separation of the testing device of the present invention.

[0020] Figure 2 Schematic diagram of the structure of the resonant cavity in the testing device of the present invention.

[0021] Figure 3 The test device of the present invention and the prior art device adopt TE 01n The electric field distribution diagram at three frequency points when the mode is tested.

[0022] Figure 4 Schematic diagram of the effects of the test device of the present invention and the prior art device on sensitivity and quality factor under different dielectric constants.

[0023] Figure 5 Schematic diagram showing the effect of different ridge heights (insertion depths) on sensitivity and quality factor in the test device of the present invention.

[0024] Figure numerals: 1 is the resonant cavity body, 2 is the upper cover plate, 3 is the side cover plate, 1-1 is the inner wall of the resonant cavity, and 1-2 is the ridge. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the implementation methods and drawings.

[0026] A dielectric constant test device based on an electric field focusing resonant cavity, the schematic diagram of its structural separation is as follows Figure 1 As shown, it includes a resonant cavity body 1, an upper cover plate 2, a side cover plate 3 and a coupling device.

[0027] The structural diagram of the resonant cavity 1 is as follows Figure 2 As shown, the whole is a "U-shaped platform", including two first and second side surfaces with "U"-shaped vertical cross-sections and parallel to each other. The inner wall 1-1 of the resonant cavity 1 is a semicircular arc, and a ridge 1-2 is provided at the lowest point of the center of the semicircular arc. The ridge consists of an upper and lower part, and the upper and lower parts are fixedly connected by embedded pins. The vertical cross-section of the ridge is trapezoidal, and its lower base is an arc with the same curvature as the inner wall of the resonant cavity 1. The upper base is a straight line and is parallel to the upper cover plate. The horizontal length of the ridge is the same as the length of the resonant cavity 1. The upper part 1-2-2 of the ridge is made of a high dielectric constant material, and the lower part 1-2-1 of the ridge is made of a metal material.

[0028] The side cover plate 3 includes a first cover plate and a second cover plate; the first cover plate is fixedly connected to the first side surface of the resonant cavity 1, the second cover plate is fixedly connected to the second side surface of the resonant cavity 1, and the upper cover plate is fixedly arranged on the top of the resonant cavity 1; a notch is provided at the center of the top edge of the first cover plate and the second cover plate;

[0029] The resonant cavity body 1, the upper cover plate 2 and the side cover plate 3 together form a semi-cylindrical resonant cavity, and the notches of the first cover plate and the second cover plate and the top of the ridge 1-2 together serve as a lofting channel;

[0030] The coupling device includes a coupling excitation device and a coupling receiving device. Coupling holes are set on the first cover plate and the second cover plate. The two coupling holes are symmetrically arranged about the ridge 2-2. The coupling excitation device is placed in one coupling hole, and the coupling receiving device is placed in the other coupling hole.

[0031] Example 1

[0032] The top of the ridge does not contact the upper cover plate 2, and the distance between the two is 0.2 mm; the width of the top of the ridge is 0.2 mm, and the height of the upper half of the ridge is 1.7 mm.

[0033] Figure 3 The test device of the present invention is different from the prior art using TE 01n When the mode is tested, the electric field distribution diagrams at three frequency points, among which (1) is the electric field distribution diagram of the test device of the present invention; (2) is the electric field distribution diagram of the prior art (CN114966225 A). As can be seen from the figure, red is the position with greater electric field intensity. The electric field distribution of the test device of the present invention is more concentrated than that of the prior art, and the concentrated area is smaller and more compact. At the same time, the red area does not diverge, and the electric field concentration intensity of the middle test area is greater, that is, the device of the present invention can better apply a strong electric field to the material to be tested. Comparison between the two shows that the present invention uses two different materials to realize the ridge, and the upper half of the ridge uses a high dielectric constant material, which can achieve an improvement in the compressive strength of the electric field in the cavity.

[0034] Figure 4 It is a schematic diagram of the effect of different dielectric constants on sensitivity and quality factor of the test device of the present invention and the prior art device. As can be seen from the figure, if a differentiated dielectric constant material is selected for the upper part of the ridge, it will have a significant impact on the key performance characteristics of the cavity - quality factor and sensitivity. When the dielectric constant exceeds the appropriate range, for example, too high may lead to a decrease in quality factor, while too low will sacrifice sensitivity. The ideal strategy is to control the dielectric constant within a moderate range, approximately between 50 and 110. Within this range, the optimal performance and stability of the cavity can be better balanced; preferably 80.

[0035] Figure 5 This diagram shows how different ridge heights (insertion depths) in the upper half of the test device affect sensitivity and quality factor. As can be seen from the figure, with increasing insertion depth, both the quality factor and sensitivity initially increase and then gradually decrease. At an insertion depth of 1.7 mm, the quality factor reaches its maximum, while the sensitivity at this point is very close to the maximum value and, when compared to the values ​​to the left and right, is close to the average. Therefore, considering both quality factor and sensitivity, a longitudinal insertion depth of 1.7 mm is preferred for materials with a dielectric constant of 80.

[0036] Table 1 shows comparative data from polytetrafluoroethylene (PTFE) testing using the test device of the present invention. As can be seen from Table 1, the change in quality factor when a dielectric is added is greater than when no dielectric is added. This indicates that the addition of a dielectric makes the field in the test area more sensitive to changes in the test material, improving the accuracy of material testing under the same conditions. Furthermore, the frequency offset is reduced compared to when no dielectric is added, indicating that the addition of the test material reduces the impact on the selected test mode, ensuring test stability. Therefore, the ridge design of the present invention improves cavity testing performance.

[0037] Table 1

[0038] ΔQ Δf(GHz) No medium added 134.652 0.38846 Add medium 470.31 0.22198

[0039] The above description is only a specific embodiment of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all disclosed features, or all steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A dielectric constant testing device based on an electric field converging resonant cavity, characterized in that: The invention comprises a resonant cavity body (1), an upper cover plate (2), a side cover plate (3) and a coupling device; wherein the resonant cavity body (1) is a "U-shaped platform" as a whole, comprising two first side surfaces and a second side surface with "U"-shaped cross sections and parallel to each other; the inner wall (1-1) of the resonant cavity body (1) is a semicircular arc, and a ridge (1-2) is provided at the lowest point of the center of the semicircular arc; the ridge is composed of an upper and a lower part; the vertical cross section of the ridge is trapezoidal, the lower bottom side is an arc, which has the same curvature as the inner wall of the resonant cavity body (1); the upper bottom side is a straight line and is parallel to the upper cover plate; the horizontal length of the ridge is the same as the length of the resonant cavity body (1); the upper part (1-2-2) and the lower part (1-2-1) of the ridge are both made of metal materials, but the dielectric constant of the material of the upper part (1-2-2) is higher than the dielectric constant of the material of the lower part (1-2-1); The side cover plate (3) comprises a first cover plate and a second cover plate; the first cover plate is fixedly connected to the first side surface of the resonant cavity (1), the second cover plate is fixedly connected to the second side surface of the resonant cavity (1), and the upper cover plate is fixedly arranged on the top of the resonant cavity (1); a notch is arranged at the center of the top edge of the first cover plate and the second cover plate; The resonant cavity body (1), the upper cover plate (2) and the side cover plates (3) together enclose a semi-cylindrical resonant cavity, and the notches of the first cover plate and the second cover plate and the top of the ridge (1-2) together serve as a lofting channel; The coupling device includes a coupling excitation device and a coupling receiving device. Coupling holes are provided on the first cover plate and the second cover plate. The two coupling holes are respectively located on different sides at both ends and are symmetrical about the central plane of the semi-cylinder. The coupling excitation device is placed in one coupling hole, and the coupling receiving device is placed in the other coupling hole.

2. The dielectric constant testing device according to claim 1, wherein: The upper part of the ridge is made of a high dielectric constant metal material with a dielectric constant of 50-110.

3. The dielectric constant testing device according to claim 2, wherein: The dielectric constant of the material of the upper portion of the ridge is 80.

4. The dielectric constant testing device according to claim 1, wherein: The upper and lower parts of the ridge are fixedly connected by built-in pins.

5. The dielectric constant testing device according to claim 1, wherein: The top of the ridge does not contact the upper cover plate (2), and the spacing between the two is 0.2 mm.

6. The dielectric constant testing device according to claim 1, wherein: The width of the top of the ridge is 0.1 to 0.4 mm, and the vertical height of the upper ridge is 1.4 to 2.5 mm.

7. The dielectric constant testing device according to claim 6, wherein: The width of the top of the ridge is 0.2 mm, and the vertical height of the upper ridge is 1.7 mm.

8. The dielectric constant testing device according to claim 7, wherein: The distance between the top of the ridge and the upper cover plate (2) is the same as the width of the top of the ridge, forming a test area with a square cross section. If the area of ​​this area is too large, the compression strength of the electric field will be insufficient, affecting the test effect; if it is too small, it will affect the processing accuracy.

9. The dielectric constant testing device according to claim 1, wherein: The inner wall of the semi-cylindrical resonant cavity and the surface of the lower half of the ridge are both silver-plated.

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