Microwave resonance sensor and sensitivity adjusting method thereof

Abstract

The present application relates to a kind of microwave resonance sensor and its sensitivity adjustment method, belong to microwave resonance sensor design technical field, wherein, microwave resonance sensor includes in the two sides of metal plate respectively setting a microstrip arm, between two microstrip arms setting up and down left and right four open resonators, wherein, left and right two open resonators form capacitive coupling, and up and down two open resonators are used to strengthen capacitive coupling, the sensitivity adjustment method of microwave resonance sensor of the present application carries out circuit equivalence to each device in microwave resonance sensor, based on the transmission coefficient of microwave resonance sensor calculated after equivalent circuit, according to transmission coefficient, realize to microwave resonance sensor carries out sensitivity adjustment.The characteristic point detected by the microwave resonance sensor with four open resonators constructed in the present application significantly improves the amount of shift, to realize the high sensitivity, non-contact identification of solution.

Description

Technical Field

[0001] This invention relates to the field of microwave resonant sensor design technology, and in particular to a microwave resonant sensor and its sensitivity adjustment method. Background Technology

[0002] Existing microwave resonant sensors have been widely used for the detection and differentiation of liquid types due to their advantages such as accurate measurement, simple structure, and low manufacturing cost. The basic principle of microwave resonant sensors is to establish the correspondence between the liquid dielectric constant and the sensor output parameters by analyzing the changes in parameters such as the resonant frequency, amplitude, phase, and bandwidth of the reflection coefficient curve, thereby realizing the identification of the solution type.

[0003] However, when the types of solutions to be tested are similar, traditional microwave resonant sensors (such as microwave sensors with a single resonator) have limited detection sensitivity and insufficient resolution, which leads to a decrease in the ability to distinguish between different liquids. Therefore, it is necessary to improve microwave resonant sensors to enhance the detection capability of different liquid types.

[0004] In summary, when the types of solutions to be tested are similar, the traditional microwave resonant sensor has limited sensitivity to detect different types of liquids, which leads to a decrease in its ability to distinguish between different liquids. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problem that when the types of solutions to be tested are similar, the traditional microwave resonant sensor has limited sensitivity to detect the types of liquids, which leads to a decrease in the ability to distinguish between different liquids.

[0006] To address the aforementioned technical problems, the present invention provides a microwave resonant sensor, comprising:

[0007] A metal plate, wherein a first microstrip arm and a second microstrip arm are provided on the metal plate, the first microstrip arm and the second microstrip arm are respectively provided on the same side of the metal plate and located on both sides of the metal plate;

[0008] A first open-end resonator, a second open-end resonator, a third open-end resonator, and a fourth open-end resonator are arranged in a counterclockwise direction between the first microstrip arm and the second microstrip arm. The openings of the first open-end resonator and the third open-end resonator correspond to each other, and the openings of the second open-end resonator and the fourth open-end resonator correspond to each other.

[0009] In one embodiment of the present invention, the angle formed between the center line of the first open-ended resonator and the center line of the second open-ended resonator is 90°, the angle formed between the center line of the second open-ended resonator and the center line of the third open-ended resonator is 90°, the angle formed between the center line of the third open-ended resonator and the center line of the fourth open-ended resonator is 90°, and the angle formed between the center line of the fourth open-ended resonator and the center line of the first open-ended resonator is 90°.

[0010] In one embodiment of the present invention, the center lines of the first and third open-end resonators are parallel to the length direction of the first or second microstrip arm, and the center lines of the second and fourth open-end resonators are perpendicular to the length direction of the first or second microstrip arm.

[0011] In one embodiment of the present invention, the distance between the first open-ended resonator and the third open-ended resonator is in the range of 1.64mm-1.8mm, and the distance between the second open-ended resonator and the fourth open-ended resonator is in the range of 1.64mm-1.8mm.

[0012] In one embodiment of the present invention, the distance between the first microstrip arm and the second open resonator is in the range of 0.2mm-0.3mm, and the distance between the second microstrip arm and the fourth open resonator is in the range of 0.2mm-0.3mm.

[0013] To address the aforementioned technical problems, this invention provides a method for adjusting the sensitivity of a microwave resonant sensor, comprising the following steps:

[0014] The inductive coupling formed between the first microstrip arm and the second open resonator is equivalent to the first circuit.

[0015] The inductive coupling formed between the second microstrip arm and the fourth open resonator is equivalent to the second circuit.

[0016] The capacitive coupling formed by arranging the openings of the second and fourth open resonators opposite each other is equivalent to the third circuit.

[0017] Calculate the equivalent impedance of the entire circuit composed of the first circuit, the second circuit, and the third circuit;

[0018] Calculate the transmission coefficient of the microwave resonant sensor based on the equivalent impedance of the entire circuit;

[0019] The sensitivity of the microwave resonant sensor can be adjusted using the transmission coefficient.

[0020] In one embodiment of the present invention, the inductive coupling formed between the first microstrip arm and the second open resonator is equivalent to a first circuit, wherein the first circuit is a first RLC circuit, and the first RLC circuit includes a first resistor R1, a first inductor L1, and a first capacitor C1 connected in parallel in sequence.

[0021] The inductive coupling formed between the second microstrip arm and the fourth open resonator is equivalent to a second circuit, wherein the second circuit is a second RLC circuit, and the second RLC circuit includes a second resistor R2, a second inductor L2, and a second capacitor C2 connected in parallel in sequence.

[0022] The capacitive coupling formed by arranging the openings of the second and fourth open-ended resonators opposite each other is equivalent to a third circuit, wherein the third circuit is a mutual capacitance. .

[0023] In one embodiment of the present invention, the method for calculating the equivalent impedance of the entire circuit composed of the first circuit, the second circuit, and the third circuit includes:

[0024] Calculate the equivalent impedance of the first RLC circuit, the equivalent impedance of the second RLC circuit, and their mutual capacitance. Equivalent impedance:

[0025] ;

[0026] ;

[0027] ;

[0028] in, This is the equivalent impedance corresponding to the first RLC circuit. The value of the first resistor R1, The value of the second resistor R2, This is the resonant frequency of the entire circuit. The value of the first capacitor C1, mutual capacitance Size, This is the equivalent impedance corresponding to the second RLC circuit. The value of the second capacitor C2, mutual capacitance The equivalent impedance, For complex units, The resonant frequency of the first RLC circuit or the second RLC circuit;

[0029] pass , , Calculate the equivalent impedance of the entire circuit. :

[0030] .

[0031] In one embodiment of the present invention, the calculation of the transmission coefficient of the microwave resonant sensor based on the equivalent impedance of the entire circuit is expressed as follows:

[0032] ;

[0033] in, denoted as the transmission coefficient of the microwave resonant sensor.

[0034] In one embodiment of the present invention, a method for adjusting the sensitivity of a microwave resonant sensor using the transmission coefficient includes:

[0035] The transmission coefficient of the microwave resonant sensor The point where the phase is 0 is used as a characteristic point of the solution. When adjusting the sensitivity of the microwave resonant sensor, two different types of solutions are needed. Containers containing the solutions are placed directly above the microwave resonant sensor to obtain the transmission coefficients of the two different solutions. The frequency of the corresponding feature point is calculated, and the difference between the frequencies of the two different solutions is used to obtain the frequency offset. The distance between different components in the microwave resonant sensor is adjusted according to the frequency offset. The larger the frequency offset, the higher the sensitivity of the microwave resonant sensor.

[0036] The technical solution of the present invention has the following advantages compared with the prior art:

[0037] The microwave resonant sensor described in this invention has a simple structure and high detection sensitivity. Since different solutions have different dielectric constants (the dielectric constant can distinguish the types of solutions), when the solution to be tested changes, the feature points detected by the microwave resonant sensor will shift. However, the microwave resonant sensor with four open resonators constructed in this invention significantly improves the shift of the feature points detected, thereby achieving high sensitivity and non-contact identification of solutions. Attached Figure Description

[0038] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0039] Figure 1 This is a schematic diagram of the microwave resonant sensor structure in an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the structure for detecting the solution in a container using a microwave resonant sensor in an embodiment of the present invention;

[0041] Figure 3 This is an equivalent schematic diagram of the microwave resonant sensor circuit in an embodiment of the present invention;

[0042] Figure 4 This is a simplified equivalent schematic diagram of the microwave resonant sensor circuit in an embodiment of the present invention. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0044] Example 1

[0045] Reference Figure 1 As shown, the present invention relates to a microwave resonant sensor, comprising:

[0046] A metal plate 1, on which a first microstrip arm 2-1 and a second microstrip arm 2-2 are provided, wherein the first microstrip arm 2-1 and the second microstrip arm 2-2 are respectively provided on the same side of the metal plate 1 and located on both sides of the metal plate 1;

[0047] A first open-end resonator 3-1, a second open-end resonator 3-2, a third open-end resonator 3-3, and a fourth open-end resonator 3-4 are arranged in a counterclockwise direction between the first microstrip arm 2-1 and the second microstrip arm 2-2. The openings of the first open-end resonator 3-1 and the third open-end resonator 3-3 correspond to each other, and the openings of the second open-end resonator 3-2 and the fourth open-end resonator 3-4 correspond to each other.

[0048] It should be noted that, in this embodiment, a first interface 5-1 and a second interface 5-2 are also provided on one side of the metal plate 1. The first microstrip arm 2-1 extends to and connects to the first interface 5-1, and the second microstrip arm 2-2 extends to and connects to the second interface 5-2. The first interface 5-1 and the second interface 5-2 are respectively connected to an external vector network analyzer (VNA) for communication. Finally, the analysis of the solution type is realized through the vector network analyzer (VNA).

[0049] Furthermore, in this embodiment, capacitive coupling is formed between the second open resonator 3-2 and the fourth open resonator 3-4, and the capacitive coupling strength is adjusted by setting the distance between the first open resonator 3-1 and the third open resonator 3-3.

[0050] Furthermore, in this embodiment, the angle formed between the center line of the first open resonator 3-1 and the center line of the second open resonator 3-2 is 90°, the angle formed between the center line of the second open resonator 3-2 and the center line of the third open resonator 3-3 is 90°, the angle formed between the center line of the third open resonator 3-3 and the center line of the fourth open resonator 3-4 is 90°, and the angle formed between the center line of the fourth open resonator 3-4 and the center line of the first open resonator 3-1 is 90°.

[0051] Furthermore, in this embodiment, the central axis of the first open-ended resonator 3-1 and the third open-ended resonator 3-3 is parallel to the length direction of the first microstrip arm 2-1 or the second microstrip arm 2-2, and the central axis of the second open-ended resonator 3-2 and the fourth open-ended resonator 3-4 is perpendicular to the length direction of the first microstrip arm 2-1 or the second microstrip arm 2-2.

[0052] Furthermore, in this embodiment, the distance between the first open-ended resonator 3-1 and the third open-ended resonator 3-3 is in the range of 1.64mm-1.8mm, and the distance between the second open-ended resonator 3-2 and the fourth open-ended resonator 3-4 is in the range of 1.64mm-1.8mm.

[0053] Furthermore, in this embodiment, the distance between the first microstrip arm 2-1 and the second open resonator 3-2 is in the range of 0.2mm-0.3mm, and the distance between the second microstrip arm 2-2 and the fourth open resonator 3-4 is in the range of 0.2mm-0.3mm.

[0054] Furthermore, in this embodiment, the first open resonator 3-1, the second open resonator 3-2, the third open resonator 3-3, and the fourth open resonator 3-4 are triangular shapes with notches. The angles of the other two corners of the triangle affect the sensitivity of the microwave resonant sensor in the same way as the distance from one side of the horizontal line where the notch is located to one side of the bottom edge of the notch triangle, with a distance range of 1.19mm-1.22mm.

[0055] Furthermore, in this embodiment, both the first microstrip arm 2-1 and the second microstrip arm 2-2 are made of metal.

[0056] Please see Figure 2 When testing the type of solution, container 6 is made of PET material and is used to hold the solution to be tested. Container 6 is placed a certain distance directly above the openings of the four open resonators.

[0057] Example 2

[0058] This invention relates to a method for adjusting the sensitivity of a microwave resonant sensor, which enables sensitivity adjustment of the microwave resonant sensor described in Embodiment 1, and includes the following steps:

[0059] (1) The inductive coupling formed between the first microstrip arm 2-1 and the second open resonator 3-2 is equivalent to the first circuit;

[0060] (2) The inductive coupling formed between the second microstrip arm 2-2 and the fourth open resonator 3-4 is equivalent to the second circuit;

[0061] (3) The capacitive coupling formed by the relative arrangement of the openings of the second open resonator 3-2 and the fourth open resonator 3-4 is equivalent to the third circuit.

[0062] (4) Calculate the equivalent impedance of the entire circuit consisting of the first circuit, the second circuit, and the third circuit;

[0063] (5) Calculate the transmission coefficient of the microwave resonant sensor based on the equivalent impedance of the entire circuit;

[0064] (6) The sensitivity of the microwave resonant sensor is adjusted by means of the transmission coefficient.

[0065] Further, please refer to Figure 3 In this embodiment, the inductive coupling formed between the first microstrip arm 2-1 and the second open resonator 3-2 is equivalent to the first circuit, wherein the first circuit is the first RLC circuit, and the first RLC circuit includes a first resistor R1, a first inductor L1, and a first capacitor C1 connected in parallel in sequence.

[0066] Further, please refer to Figure 3 In this embodiment, the inductive coupling formed between the second microstrip arm 2-2 and the fourth open resonator 3-4 is equivalent to the second circuit, wherein the second circuit is the second RLC circuit, and the second RLC circuit includes a second resistor R2, a second inductor L2, and a second capacitor C2 connected in parallel in sequence.

[0067] Further, please refer to Figure 3 In this embodiment, the capacitive coupling formed by the opposite arrangement of the openings of the second open-ended resonator 3-2 and the fourth open-ended resonator 3-4 is equivalent to a third circuit, wherein the third circuit is a mutual capacitance. (i.e., coupling capacitor) Figure 3 This shows the relationship of capacitive coupling. Figure 4 This can make subsequent transmission coefficients more convenient calculate.

[0068] Further, please refer to Figure 4In this embodiment, the simplified microwave resonant sensor circuit includes: a first RLC circuit connected in parallel with a capacitor -Cm, a second RLC circuit connected in parallel with a capacitor -Cm, and the first RLC circuit with capacitor -Cm connected in parallel and the second RLC circuit with capacitor -Cm connected in parallel are connected in series with capacitor Cm, thereby forming the entire circuit of the microwave resonant sensor.

[0069] Furthermore, the method for calculating the equivalent impedance of the entire circuit composed of the first circuit, the second circuit, and the third circuit in this embodiment includes:

[0070] Calculate the equivalent impedance of the first RLC circuit, the equivalent impedance of the second RLC circuit, and their mutual capacitance. Equivalent impedance:

[0071] ;

[0072] ;

[0073] ;

[0074] in, This is the equivalent impedance corresponding to the first RLC circuit. The value of the first resistor R1, The value of the second resistor R2, This is the resonant frequency of the entire circuit. The value of the first capacitor C1, mutual capacitance Size, This is the equivalent impedance corresponding to the second RLC circuit. The value of the second capacitor C2, mutual capacitance The equivalent impedance, The unit is a complex number, because this embodiment studies the left-right symmetrical case of the first RLC circuit and the second RLC circuit (i.e., , , ),therefore This is the resonant frequency of the first or second RLC circuit.

[0075] pass , , Calculate the equivalent impedance of the entire circuit. :

[0076] .

[0077] Furthermore, the transmission coefficient of the microwave resonant sensor is calculated based on the equivalent impedance of the entire circuit, and expressed as:

[0078] ;

[0079] in, This represents the transmission coefficient of the microwave resonant sensor. In actual detection, the transmission coefficient... The data is obtained by connecting a vector network analyzer (VNA) to the first interface 5-1 and the second interface 5-2 of the microwave resonant sensor in this embodiment.

[0080] Furthermore, the method for adjusting the sensitivity of a microwave resonant sensor through the transmission coefficient in this embodiment includes:

[0081] The transmission coefficient of the microwave resonant sensor The point where the phase is 0 is used as a characteristic point of the solution. When adjusting the sensitivity of the microwave resonant sensor, two different types of solutions are needed. Containers containing the solutions are placed directly above the microwave resonant sensor to obtain the transmission coefficients of the two different solutions. The frequency offset is obtained by calculating the difference between the frequencies of the corresponding feature points and the frequencies of the two different solutions. The distance between different devices in the microwave resonant sensor (i.e., the distance between open resonators, the distance between open resonators and microstrip arms, etc.) is adjusted according to the frequency offset. The larger the frequency offset, the higher the sensitivity of the microwave resonant sensor.

[0082] Changes in the dielectric constant of a liquid sample (different liquids have different dielectric constants) will cause capacitance. , , Changes in [the value] thus affect the transmission coefficient. The phase (the point where the phase is 0 is the characteristic point) is determined by the transmission coefficient. According to the formula, when the type of liquid changes, the capacitance... , , The frequency (resonant frequency) corresponding to the characteristic point changes as the liquid varies, therefore, it is only necessary to measure and analyze the transmission coefficient. By using the resonant frequency, non-contact detection of liquid types can be achieved.

[0083] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0084] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A microwave resonant sensor, characterized in that: include: A metal plate (1) is provided with a first microstrip arm (2-1) and a second microstrip arm (2-2). The first microstrip arm (2-1) and the second microstrip arm (2-2) are respectively provided on the same side of the metal plate (1) and located on both sides of the metal plate (1). A first open-end resonator (3-1), a second open-end resonator (3-2), a third open-end resonator (3-3), and a fourth open-end resonator (3-4) are arranged in a counterclockwise direction between the first microstrip arm (2-1) and the second microstrip arm (2-2). The openings of the first open-end resonator (3-1) and the third open-end resonator (3-3) correspond to each other, and the openings of the second open-end resonator (3-2) and the fourth open-end resonator (3-4) correspond to each other. The angle between the center line of the first open resonator (3-1) and the center line of the second open resonator (3-2) is 90°. The angle between the center line of the second open resonator (3-2) and the center line of the third open resonator (3-3) is 90°. The angle between the center line of the third open resonator (3-3) and the center line of the fourth open resonator (3-4) is 90°. The angle between the center line of the fourth open resonator (3-4) and the center line of the first open resonator (3-1) is 90°. The center lines of the first open-end resonator (3-1) and the third open-end resonator (3-3) are parallel to the length direction of the first microstrip arm (2-1) or the second microstrip arm (2-2), and the center lines of the second open-end resonator (3-2) and the fourth open-end resonator (3-4) are perpendicular to the length direction of the first microstrip arm (2-1) or the second microstrip arm (2-2).

2. The microwave resonant sensor according to claim 1, characterized in that: The distance between the first open-ended resonator (3-1) and the third open-ended resonator (3-3) is 1.64mm-1.8mm, and the distance between the second open-ended resonator (3-2) and the fourth open-ended resonator (3-4) is 1.64mm-1.8mm.

3. The microwave resonant sensor according to claim 1, characterized in that: The distance between the first microstrip arm (2-1) and the second open resonator (3-2) is in the range of 0.2mm-0.3mm, and the distance between the second microstrip arm (2-2) and the fourth open resonator (3-4) is in the range of 0.2mm-0.3mm.

4. A method for adjusting the sensitivity of a microwave resonant sensor, comprising adjusting the sensitivity of the microwave resonant sensor according to any one of claims 1-3, characterized in that: Includes the following steps: The inductive coupling formed between the first microstrip arm (2-1) and the second open resonator (3-2) is equivalent to the first circuit; The inductive coupling formed between the second microstrip arm (2-2) and the fourth open resonator (3-4) is equivalent to the second circuit; The capacitive coupling formed by the relative arrangement of the openings of the second open resonator (3-2) and the fourth open resonator (3-4) is equivalent to the third circuit. Calculate the equivalent impedance of the entire circuit composed of the first circuit, the second circuit, and the third circuit; Calculate the transmission coefficient of the microwave resonant sensor based on the equivalent impedance of the entire circuit. The sensitivity of the microwave resonant sensor can be adjusted using the transmission coefficient.

5. The microwave resonant sensor sensitivity adjustment method according to claim 4, characterized in that: The inductive coupling formed between the first microstrip arm (2-1) and the second open resonator (3-2) is equivalent to a first circuit, wherein the first circuit is a first RLC circuit, and the first RLC circuit includes a first resistor R1, a first inductor L1, and a first capacitor C1 connected in parallel in sequence. The inductive coupling formed between the second microstrip arm (2-2) and the fourth open resonator (3-4) is equivalent to a second circuit, wherein the second circuit is a second RLC circuit, and the second RLC circuit includes a second resistor R2, a second inductor L2, and a second capacitor C2 connected in parallel in sequence. The capacitive coupling formed by arranging the openings of the second open-ended resonator (3-2) and the fourth open-ended resonator (3-4) opposite each other is equivalent to a third circuit, wherein the third circuit is a mutual capacitance. .

6. The microwave resonant sensor sensitivity adjustment method according to claim 5, characterized in that: Methods for calculating the equivalent impedance of the entire circuit composed of the first circuit, the second circuit, and the third circuit include: Calculate the equivalent impedance of the first RLC circuit, the equivalent impedance of the second RLC circuit, and their mutual capacitance. Equivalent impedance: ； ； ； in, This is the equivalent impedance corresponding to the first RLC circuit. The value of the first resistor R1, The value of the second resistor R2, This is the resonant frequency of the entire circuit. The value of the first capacitor C1, mutual capacitance Size, This is the equivalent impedance corresponding to the second RLC circuit. The value of the second capacitor C2, mutual capacitance The equivalent impedance, For complex units, The resonant frequency of the first RLC circuit or the second RLC circuit; pass , , Calculate the equivalent impedance of the entire circuit. : 。 7. The microwave resonant sensor sensitivity adjustment method according to claim 6, characterized in that: The transmission coefficient of the microwave resonant sensor, calculated based on the equivalent impedance of the entire circuit, is expressed as follows: ； in, denoted as the transmission coefficient of the microwave resonant sensor.

8. The microwave resonant sensor sensitivity adjustment method according to claim 7, characterized in that: The methods for adjusting the sensitivity of a microwave resonant sensor using the transmission coefficient include: The transmission coefficient of the microwave resonant sensor The point where the phase is 0 is taken as the characteristic point of the solution. When adjusting the sensitivity of the microwave resonant sensor, two different types of solutions are needed. Containers containing the solutions are placed directly above the microwave resonant sensor to obtain the transmission coefficients of the two different solutions. The frequency offset is obtained by calculating the frequency difference between the corresponding frequencies of the two different solutions and corresponding feature points. The distance between different components in the microwave resonant sensor is adjusted according to the frequency offset. The larger the frequency offset, the higher the sensitivity of the microwave resonant sensor.

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