A microstrip coupling structure dual-band dielectric constant microwave sensor

Abstract

The application discloses a dielectric constant microwave sensor with a microstrip coupling line structure and particularly relates to the technical field of microwave sensing, and comprises a metal transmission line on an upper layer, a dielectric substrate on a middle layer and a grounded metal plate on a bottom layer; a signal path of the upper layer structure of the microwave sensor is arranged between the first port and the second port, and the signal path is composed of at least one transmission line, four coupling lines and two metalized through holes. The microstrip coupling line structure adopted in the application is sensitive to changes in the dielectric constant of external materials, has the advantages of small size, easy processing, low cost, high precision and the like, different sizes of the microstrip coupling line provide two measurement working frequency bands, and the microwave sensor can be effectively applied to solid dielectric constant measurement work.

Description

Technical Field

[0001] This invention belongs to the field of microwave technology, specifically relating to a dual-band dielectric constant microwave sensor with a microstrip coupling structure. Background Technology

[0002] With the rapid development of 5G, IoT, and intelligent detection technologies, the demand for real-time monitoring of dielectric parameters is becoming increasingly urgent. Dielectric constant, as a key parameter characterizing the electromagnetic properties of materials, is crucial for accurate measurement in fields such as chemical engineering, food processing, and biomedicine. Traditional sensing technologies, such as capacitive and resistive methods, face bottlenecks such as signal distortion and weak anti-interference capabilities in high-frequency scenarios, making them particularly unsuitable for dynamic detection needs in complex media environments. Dielectric constant microwave sensors, relying on the interaction mechanism between microwaves and media, can utilize the phase, amplitude, or frequency shift of electromagnetic waves propagating in the medium to achieve high-precision measurement of the dielectric constant. Their unique advantages include: non-contact detection through non-conductive media, stronger stability against environmental interference such as temperature and humidity, and high integration with microwave circuits. Driven by the trends of industrial automation, non-destructive testing, and miniaturization in wearable devices, dielectric constant microwave sensors are becoming core components driving the upgrade of intelligent sensing technologies due to their high-frequency response characteristics and miniaturization potential. Therefore, designing high-performance, miniaturized dielectric constant microwave sensors has significant academic research value and promising engineering application prospects. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a dual-band dielectric constant microwave sensor with a microstrip coupling structure, which is a miniaturized, high-precision, and high-sensitivity dual-band high-performance microwave sensor.

[0004] Technical solution: To achieve the above objectives, the present invention provides the following technical solution: A dual-band dielectric constant microwave sensor with a microstrip coupling structure includes an upper metal transmission line, a middle dielectric substrate, a bottom ground metal plate, a first port, and a second port. The signal path of the upper structure of the filter is arranged between the first port and the second port. The signal path consists of at least one transmission line, four coupling lines, and two metallized vias. The four coupling lines include a first coupling line, a second coupling line, a third coupling line, and a fourth coupling line. The metallized vias include a first metallized via and a second metallized via. One end of the first coupling line is connected to the first port, and the other end is connected to one end of the second coupling line. The other end of the second coupling line is grounded through the first metallized via. The other end of the second coupling line is connected to the transmission line, and the other end of the third coupling line is connected to one end of the transmission line, and the other end is connected to one end of the fourth coupling line. The other end of the fourth coupling line is connected to the second port, and the other end of the fourth coupling line is grounded through the second metallized via. As a further optimization of the present invention, the first coupling line is the same as the third coupling line, and the second coupling line is the same as the fourth coupling line.

[0005] As a further optimization of the present invention, the first coupling line and the third coupling line, the second coupling line and the fourth coupling line are all symmetrical about the center of the transmission line, which facilitates the measurement of the dielectric material.

[0006] As a further optimization of the present invention, the electrical lengths of the first coupling line, the second coupling line, the third coupling line and the fourth coupling line are all approximately 90°, generating a resonant point for dielectric constant measurement.

[0007] As a further optimization of the present invention, the electrical length of the transmission line is approximately 180°, connecting the first coupling line, the second coupling line, the third coupling line, and the fourth coupling line, which are symmetrically arranged vertically.

[0008] The technical effects and advantages provided by the present invention in the above technical solution are as follows: 1. The dual-band dielectric constant microwave sensor with microstrip coupling structure proposed in this invention has the advantages of small size, easy processing, low cost and easy integration.

[0009] 2. The dual-band dielectric constant microwave sensor with a microstrip coupling structure proposed in this invention has the characteristic of operating at two different frequencies with the same measurement system, effectively meeting this requirement. By acquiring measurement data at two frequencies respectively, the dual-band microwave sensor can simultaneously measure multiple parameters, thus adapting to the detection requirements in complex environments. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0011] Figure 1 This is a perspective view of an embodiment of the present invention; Figure 2 This is a top view of an embodiment of the present invention; Figure 3 This is a simulated dielectric constant measurement curve from an embodiment of the present invention.

[0012] In the attached diagram: 1-First port, 2-Second port, 3-First coupling line, 4-Second coupling line, 5-Transmission line, 6-Third coupling line, 7-Fourth coupling line, 8-First metallized via, 9-Second metallized via, 10-Metallic transmission line, 11-Ground metal plate, 12-Dielectric substrate. Detailed Implementation

[0013] The following embodiments are provided to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0014] Figure 1 This is a perspective view of a dual-band dielectric constant microwave sensor with a microstrip coupling structure according to an embodiment of the present invention; see also Figure 1 It includes a bottom grounding metal plate 11, a middle dielectric substrate 12, an upper metal transmission line 10, a first port 1, and a second port 2.

[0015] Figure 2 This is a plan view of a dual-band dielectric constant microwave sensor with a microstrip coupling structure according to an embodiment of the present invention; see also Figure 2The signal path of the upper structure of the microwave sensor is arranged between the first port 1 and the second port 2. The signal path consists of at least one transmission line 5 and four coupling lines, including a first coupling line 3, a second coupling line 4, a third coupling line 6, and a fourth coupling line 7. The front end of one side of the first coupling line 3 is connected to the first port 1, and the rear end is connected to the front end of one side of the second coupling line 4. The rear end of the other side is connected to the grounding metal plate 11 through a first metallized through-hole 8. The rear end of one side of the second coupling line 4 is connected to the front end of the transmission line 5, and the front end of the other side is connected to the grounding metal plate 11 through a first metallized through-hole 8. The rear end of the transmission line 5 is connected to the front end of one side of the third coupling line. The rear end of one side of the third coupling line is connected to the front end of one side of the fourth coupling line. The rear end of the other side is connected to the grounding metal plate 11 through a second metallized through-hole 9. The rear end of one side of the fourth coupling line is connected to the second port 2, and the front end of the other side is connected to the grounding metal plate 11 through a second metallized through-hole 9.

[0016] Based on the structure described above, and the electrical lengths of the transmission lines and coupling lines, the transmission line impedance of the microwave sensor is optimized using circuit simulation software, resulting in a dual-band dielectric constant microwave sensor circuit with a microstrip coupling structure. The physical lengths corresponding to the electrical lengths of the first coupling line 3, the second coupling line 4, the third coupling line 6, the fourth coupling line 7, and the transmission line 5 are calculated using circuit simulation software, along with the physical widths corresponding to their impedances. By optimizing the physical lengths and widths of these components, a more accurate physical structure diagram is obtained. This physical structure diagram is then modeled and simulated using electromagnetic simulation software. A more accurate microwave sensor performance is obtained through full-wave simulation of the physical structure.

[0017] Figure 3This is a simulated dielectric constant measurement curve of the proposed microwave sensor. In the simulation, the dielectric constant was set to range from 1 to 8, varying in increments of 1, covering the coupling line region of the microwave sensor to simulate different materials that might be encountered in actual measurements. The simulation results show that as the dielectric constant of the measured material gradually increases, the resonant frequency of the microwave sensor in both operating frequency bands shifts towards lower frequencies. Simulation results show that, with a 4.5 GHz separation between the two operating frequency bands, the unloaded resonant frequencies of the first and second frequency bands are 4.35 GHz and 7.57 GHz, respectively, when no test material is placed. However, with the placement of a test material with a dielectric constant of 8, the resonant frequency of the first frequency band shifts to 2.69 GHz, with a total resonant frequency shift of 1.66 GHz. Simultaneously, the resonant frequency of the second frequency band also shifts to 4.82 GHz, with a total resonant frequency shift of 2.75 GHz. Based on this simulation result, it can be inferred that in actual testing, the dielectric constant of the material under test can be calculated by measuring the offset of the resonant frequency of the microwave sensor.

[0018] The substrate used in this embodiment is a high-frequency substrate with a dielectric constant of 2.2 and a loss tangent of 0.0009. See [link to relevant documentation]. Figure 2 The transmission line, coupling line, metallized vias, first port, and second port are all made of copper. The filter measures 35mm × 30mm. This invention's dual-band dielectric constant microwave sensor meets the current requirements for highly integrated and stable material dielectric constant measurement.

[0019] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A dual-band dielectric constant microwave sensor with a microstrip coupling structure, characterized in that, include: The upper metal transmission line (10), the lower ground metal plate (11), the middle dielectric substrate (12), the first port (1) and the second port (2); The signal path of the upper structure of the microwave sensor is arranged between the first port (1) and the second port (2). The signal path consists of at least one transmission line (5), four coupling lines and two metallized vias. The four coupling lines include the first coupling line (3), the second coupling line (4), the third coupling line (6) and the fourth coupling line (7). The metallized vias include the first metallized via (8) and the second metallized via (9). One end of the first coupling line (3) is connected to the first port (1), and the other end is connected to one end of the second coupling line (4). The other end is grounded through the first metallized through hole (8). One end of the second coupling line (4) is connected to the transmission line (5), and the other end is grounded through the first metallized through hole (8); One end of the third coupling line (6) is connected to the other end of the transmission line (5), and the other end is connected to one end of the fourth coupling line (7). The other end is grounded through the second metallized through hole (9). One end of the fourth coupling line (6) is connected to the second port (2), and the other end is grounded through the second metallized through hole (9).

2. The dual-band dielectric constant microwave sensor with a microstrip coupling structure according to claim 1, characterized in that: The first coupling line (3) is the same as the third coupling line (6), and the second coupling line (4) is the same as the fourth coupling line (6).

3. A dual-band dielectric constant microwave sensor with a microstrip coupling structure according to claim 1, characterized in that: The first coupling line (3) and the third coupling line (6), the second coupling line (4) and the fourth coupling line (6) are all symmetrical about the center of the transmission line (5).

4. A dual-band dielectric constant microwave sensor with a microstrip coupling structure according to claim 1, characterized in that: The electrical lengths of the first coupling line (3), the second coupling line (4), the third coupling line (6) and the fourth coupling line (6) are all approximately 90°.

5. A dual-band dielectric constant microwave sensor with a microstrip coupling structure according to claim 1, characterized in that: The electrical length of the transmission line (5) is approximately 180°.

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