Open structure microwave cavity for liquid discrimination based on substrate integrated waveguide

Abstract

This invention relates to an open-structure microwave cavity for liquid identification based on a substrate-integrated waveguide, comprising a ground plane layer, a dielectric substrate, a metal patch layer, a metal pillar array, and a coaxial feed connector. The metal pillar array penetrates the metal patch layer and the dielectric substrate, and is arranged around the periphery of the metal patch layer. A slit for concentrating microwave energy radiation is formed on the metal patch layer, located within the area enclosed by the metal pillar array. The outer shell of the coaxial feed connector is fixed to the ground plane layer. The central probe of the coaxial feed connector sequentially passes through the ground plane layer and the dielectric substrate, and is electrically connected to the metal patch layer. The coaxial feed connector is connected to a signal acquisition and processing device via a feed line. The open structure allows the sample to be placed directly on the cavity for testing, enabling non-destructive and rapid capture of the unique dielectric properties of different liquids, and facilitating rapid on-site identification of liquid authenticity.

Description

Technical Field

[0001] This utility model relates to the field of microwave cavity technology, specifically to an open-structure microwave cavity for liquid identification based on a substrate integrated waveguide. Background Technology

[0002] With the continuous improvement of living standards and increasing health awareness among Chinese residents, the market size of high-end liquid products (such as fine wines and imported olive oil) continues to expand. However, the technology for identifying their authenticity faces severe challenges. Current testing methods are insufficient for rapid identification of genuine products. Existing methods, such as laboratory chemical testing, while highly accurate, are time-consuming and costly. Other testing methods are primarily based on physical sensory identification, which is easily affected by subjective factors and lacks reliability. This technological lag creates blind spots in market supervision, making it difficult to identify counterfeit and substandard liquids. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an open-structure microwave cavity for liquid identification based on a substrate integrated waveguide.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An open-structure microwave cavity for liquid identification based on substrate integrated waveguides includes a ground plane layer, a dielectric substrate, a metal patch layer, a metal pillar array, and a coaxial feed connector.

[0006] The ground plane is fixedly connected to the back end face of the dielectric substrate layer, and the metal patch layer is fixedly connected to the front end face of the dielectric substrate layer.

[0007] The metal pillar array penetrates the metal patch layer and the dielectric substrate, and the metal pillar array is arranged around the periphery of the metal patch layer.

[0008] The metal patch layer has a slit for concentrating microwave energy radiation, and the slit is located within the area enclosed by the metal column array;

[0009] The outer shell of the coaxial power connector is fixed on the ground plane; the center probe of the coaxial power connector passes through the ground plane and the dielectric substrate in sequence and is electrically connected to the metal patch layer.

[0010] The coaxial power connector is connected to the signal acquisition and processing device via a feeder cable.

[0011] Furthermore, the ground plane, dielectric substrate, and metal patch layer are cylindrical in shape to match each other.

[0012] Furthermore, the material of the dielectric substrate is RT5880.

[0013] Furthermore, the metal pillar array is a copper metal pillar array.

[0014] Furthermore, the coaxial power connector is an SMA connector.

[0015] Furthermore, the signal acquisition and processing device is a vector network analyzer.

[0016] Furthermore, the outer shell of the coaxial power connector is fixed to the ground plane by welding.

[0017] By adopting the above technical solution, the beneficial effects of this utility model are as follows:

[0018] 1. This utility model adopts a unique open cavity design. The sample to be tested only needs to be placed in a non-metallic container and directly placed on the metal patch layer of the cavity to start the test, which eliminates the complicated sample loading and sealing process and is easy to operate.

[0019] 2. By designing slits on the metal patch layer and effectively limiting electromagnetic wave leakage using a surrounding array of metal pillars, microwave energy can be concentrated and radiated onto the sample area under test, enhancing the efficiency of signal-sample interaction. This ensures operational safety, reduces external interference, and guarantees the stability and accuracy of the detection signal. Attached Figure Description

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0021] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0022] Figure 2 This is a top view of the present invention;

[0023] Figure 3 This is a cross-sectional view of the present invention during testing. Detailed Implementation

[0024] like Figure 1-3 As shown, the present invention is an open-structure microwave cavity for liquid identification based on substrate integrated waveguide, including a ground plane layer 1, a dielectric substrate 2, a metal patch layer 3, a metal pillar array 4, and a coaxial feed connector 5.

[0025] Ground plane layer 1, dielectric substrate 2, and metal patch layer 3 are all cylindrical in shape and are adapted to each other. Ground plane layer 1 is fixedly connected to the back end face of dielectric substrate 2 by bonding or pressing, and metal patch layer 3 is fixedly connected to the front end face of dielectric substrate 2 in the same way.

[0026] The metal pillar array 4 consists of multiple copper metal pillars that vertically penetrate the metal patch layer 3 and the dielectric substrate 2, and finally abut against the ground plane layer 1. The metal pillar array 4 is arranged in a ring at equal intervals around the periphery of the metal patch layer 3, thereby forming a cylindrical resonant cavity together with the ground plane layer 1, the dielectric substrate 2, and the metal patch layer 3 to limit the energy leakage of electromagnetic waves.

[0027] On the metal patch layer 3, a specific slit 31 is formed inside the annular region enclosed by the metal pillar array 4. The slit 31 can be square, circular, or other shapes, and is used to concentrate the microwave energy in the cavity and radiate it outward, thereby forming an electromagnetic field region for detection above the metal patch layer 3.

[0028] The coaxial power connector 5 uses a standard SMA connector, and its metal housing is firmly fixed to the ground plane layer 1 by welding. The center probe of the SMA connector passes through the pre-drilled holes in the ground plane layer 1 and the dielectric substrate 2 in sequence, and then makes an electrical connection with the upper metal patch layer 3, thereby injecting microwave signals into the cavity.

[0029] The coaxial power connector 5 is connected to a vector network analyzer (VNA), which is a signal acquisition and processing device, via a feed line (not shown in the figure).

[0030] The dielectric substrate 2 is made of RT5880 material (a high-performance polytetrafluoroethylene (PTFE)-based high-frequency material produced by Rogers Corporation), which has extremely low dielectric constant and dielectric loss.

[0031] The structural parameters of the metal pillar array 4 are designed to satisfy the following relationship to ensure that it can effectively simulate a continuous metal wall and suppress energy leakage:

[0032] D < 0.1λg, d < 4D, d < 0.2R eff ;

[0033] Where D is the diameter of a single metal pillar, d is the distance between the centers of adjacent metal pillars, λg is the effective wavelength of the waveguide, and R... eff Let be the equivalent radius of the substrate integrated waveguide, where (R is the physical radius of the cavity.)

[0034] When the microwave cavity of this invention is in operation, its detection method specifically includes the following steps:

[0035] First, a vector network analyzer is used as the signal source, establishing an electrical connection with the microwave cavity via a feeder to provide stable power to the entire system and ensure the normal operation of the signal transmission link. Second, the swept frequency signal, output from the vector network analyzer, is transmitted into the microwave cavity via the feeder. At the back of the cavity, the signal is guided through the dielectric substrate via an SMA connector to the metal patch layer, completing the signal transmission path within the microwave cavity and laying the foundation for subsequent microwave signal processing and analysis. Then, when the signal reaches the metal patch layer, a special slit structure is designed on the metal patch layer. The electromagnetic field excited by the signal in the metal patch layer generates displacement currents at the slits. These displacement currents propagate outward in the form of radiation at the slits, thereby coupling the signal energy from the metal patch layer to the sample under test placed on the metal patch layer (the liquid under test (such as a fine wine) is placed in a non-metallic container 6 (such as a glass bottle) and positioned directly above the slits of the metal patch layer). The radiated signal interacts with the sample under test, forming a specific electromagnetic field distribution. The dielectric constant of the sample under test has a significant impact on the propagation characteristics of electromagnetic waves, and its change alters the electromagnetic field distribution and resonance characteristics. Due to the change in the dielectric constant of the sample, the resonant frequency and electromagnetic field distribution change, leading to a corresponding change in the signal reflection characteristics. Specifically, this manifests as a shift in the resonant point of the S11 parameter (reflection coefficient) measured by the vector network analyzer. This shift in the resonant point reflects a change in the signal reflection characteristics, which is closely related to the change in the dielectric constant of the sample and can be used to identify the authenticity of liquids. Finally, the vector network analyzer collects and performs preliminary processing on the measured S11 parameters, including data filtering and smoothing, to improve the accuracy and reliability of the data. The processed S11 parameters are then compared with the S11 parameters of a pre-set standard genuine sample. By comparing the position and amplitude of the resonant point, the quality of the sample is determined. If the sample quality is good, its...

[0036] The resonant point position and amplitude of the S11 parameter should be similar to those of the standard genuine sample; conversely, if the resonant point shifts significantly or the amplitude changes drastically, it indicates that the sample may have quality issues and can be identified as a counterfeit product. Comparative analysis can help users quickly and accurately determine the authenticity of the liquid.

[0037] The microwave cavity provided by this invention, through its specific open structure and detection process, enables non-destructive and rapid detection of liquid samples. Its operation is simple; the sample is merely placed on the cavity, making it particularly suitable for applications such as on-site market inspections.

[0038] The specific embodiments of this utility model have been described above. However, those skilled in the art should understand that this is only an example. Those skilled in the art can make various changes or modifications to this embodiment without departing from the principle and essence of this utility model, but all such changes and modifications fall within the protection scope of this utility model.

Claims

1. An open structure microwave cavity for liquid discrimination based on a substrate integrated waveguide, characterized in that: It includes a ground plane layer, a dielectric substrate, a metal patch layer, a metal pillar array, and a coaxial power supply connector; The ground plane is fixedly connected to the back end face of the dielectric substrate layer, and the metal patch layer is fixedly connected to the front end face of the dielectric substrate layer. The metal pillar array penetrates the metal patch layer and the dielectric substrate, and the metal pillar array is arranged around the periphery of the metal patch layer. The metal patch layer has a slit for concentrating microwave energy radiation, and the slit is located within the area enclosed by the metal column array; The outer shell of the coaxial power connector is fixed on the ground plane; the center probe of the coaxial power connector passes through the ground plane and the dielectric substrate in sequence and is electrically connected to the metal patch layer. The coaxial power connector is connected to the signal acquisition and processing device via a feeder cable.

2. The open-structure microwave cavity for liquid identification based on substrate integrated waveguide according to claim 1, characterized in that: The ground plane, dielectric substrate, and metal patch layer are cylindrical in shape and are adapted to each other.

3. The open-structure microwave cavity for liquid identification based on substrate integrated waveguide according to claim 1, characterized in that: The dielectric substrate is made of RT5880.

4. The open-structure microwave cavity for liquid identification based on substrate integrated waveguide according to claim 1, characterized in that: The metal pillar array is a copper metal pillar array.

5. The open-structure microwave cavity for liquid identification based on substrate integrated waveguide according to claim 1, characterized in that: The coaxial power connector is an SMA connector.

6. The open-structure microwave cavity for liquid identification based on substrate integrated waveguide according to claim 1, characterized in that: The signal acquisition and processing device is a vector network analyzer.

7. The open-structure microwave cavity for liquid identification based on substrate integrated waveguide according to claim 1, characterized in that: The outer shell of the coaxial power connector is fixed to the ground plane by welding.

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