Quarter substrate integrated waveguide sensor based on CSRR

Abstract

The CSRR-based quarter substrate integrated waveguide sensor comprises a dielectric substrate, a square ring metal layer is arranged on the upper surface of the dielectric substrate, a lower metal layer is arranged on the lower surface of the dielectric substrate, and a row of metal holes are uniformly distributed in the circumferential direction of the square ring metal layer; the upper surface of the dielectric substrate is also provided with four triangular metal patches with different sizes, and each edge of the square ring metal layer is connected with one triangular metal patch; two concentric annular CSRRs are etched on the vertex angle, far away from the square ring metal layer, of the triangular metal patch. The sensor is novel in design, four mutually independent poles are generated, simultaneous multiband operation is realized, efficiency is improved, errors and loss are reduced, the size of the sensor is reduced by about 75% by adopting the QMSIW, and the sensor has the advantages of being small in size, easy to integrate, high in flexibility, low in loss and high in sensitivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and particularly relates to a quarter substrate integrated waveguide sensor based on CSRR. Background Art

[0002] In the industrial field and daily life, one of the key means to identify the type of material is the accurate measurement of the dielectric properties of the material. In the radio frequency (RF) and microwave fields, the dielectric constant, as the core parameter of dielectric properties, is particularly important for the characterization of material properties. Pulverized coal is often used as a fuel in industrial production and daily life, but moisture or impurities can cause incomplete combustion of pulverized coal, producing harmful substances. Reasonable utilization of pulverized coal can not only optimize its application effect but also reduce the negative impact on the environment. Therefore, measuring the dielectric constant of pulverized coal to evaluate its moisture content and composition is crucial for ensuring its safe and efficient use. When a material sample is placed in a microwave resonant sensor, its subtle perturbation of the electric field will cause a change in the transmission characteristics of the sensor, specifically manifested as a change in the amplitude of the S-parameter curve or a shift in the resonant frequency. In recent years, many sensors based on the microwave resonance principle have been proposed and experimentally verified in measuring the dielectric constant of materials. Microstrip structure sensors have advantages in terms of volume, cost, and design flexibility, but their performance in high-frequency applications may be inferior to that of substrate integrated waveguide (SIW) sensors.

[0003] The substrate integrated waveguide (SIW) structure has the characteristics of low loss of planar structures and easy integration of non-planar structures. It has the advantages of compact structure, strong versatility, high integration, low insertion loss, and strong power handling ability, and is widely used in the design of various microwave devices. Han et al. proposed a SIW microwave sensor loaded with complementary curved ring resonators for measuring the dielectric constant of substrate materials. The experimental results show that the sensor has the characteristics of high sensitivity and high resolution. The solid dielectric constant measurement sensor based on the IDE-ELC SIW resonator has the characteristics of low cost, non-invasive, and high sensitivity, but it is difficult to miniaturize the sensor designed using full-mode substrate integrated waveguides (FMSIWs). The prior art introduced the FMSIW, the smaller-sized half-mode substrate integrated waveguide (HMSIW), and the quarter-mode substrate integrated waveguide (QMSIW) model with even smaller size. Wu and Zhao proposed a microwave measurement system for the complex dielectric constant of liquid samples based on the improved HMSIW. It combines a passive resonant sensor with a radio frequency circuit, eliminates the dependence on expensive VNAs, and reduces costs. However, due to the absence of a VNA, its error is large. The QMSIW microwave resonant sensor proposed by T. Qi, G. Liu, J. Yu et al., “A Quarter-Mode Substrate Integrated Waveguide Microwave Sensor Loaded With CCRR for Solid Material Measurement,” IEEE Sensors Journal, vol. 23, no. 18, pp. 21105-21112, 2023 has a compact waveguide structure compared with the HMSIW, is small in volume, and is convenient for integration and deployment.

[0004] Microwave planar sensors usually adopt split-ring resonators (SRRs) and CSRR structures. Ebrahimi et al. proposed a microwave sensor using a pair of SSRs. This sensor loads a pair of identical SRRs on both sides of the microstrip line and uses one of them as a differential measurement reference, improving the anti-interference ability. However, since the SRR structure must be on the same plane as the microstrip line, it is difficult to miniaturize and highly integrate. As a new type of sensor resonant structure, CSRR shows advantages in specific application scenarios with excellent performance such as high sensitivity and is widely used in various microwave fields, including sensors, filters, antennas, etc. Compared with the SRR structure, the CSRR structure does not need to be on the same plane as the microstrip line but is etched on the ground of the sensor, making the size of the sensor more compact. Existing literature has compared the influence of different numbers of CSRRs on the electric field strength, and experiments show that the electric field strength becomes stronger with the increase in the number of rings. Inspired by these, we etched two nested open-loop resonators onto the surface of the QMSIW. While improving the sensor sensitivity, the size of the sensor is significantly reduced to 40×40 mm 2 . In the prior art, a QMSIW sensor loaded with CSRR is proposed. The QMSIW maintains the advantages of low loss and high efficiency while reducing the device size, and the introduction of CSRR provides additional flexibility for the frequency tuning and performance optimization of the sensor, while further reducing the device size. However, these sensors usually achieve high-sensitivity measurement at a single frequency point and are easily affected by various external and system-inherent factors, resulting in an increase in errors. Currently, there is no literature widely reporting the use of multiple poles to measure the dielectric properties of a single material. Summary of the Invention

[0005] The object of the present invention is to provide a quarter-substrate integrated waveguide sensor based on CSRR.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A quarter-substrate integrated waveguide sensor based on CSRR includes a dielectric substrate. A square-ring metal layer is provided on the upper surface of the dielectric substrate, and a lower metal layer is provided on the lower surface of the dielectric substrate. A row of metal holes is evenly distributed circumferentially on the square-ring metal layer, and the metal holes penetrate through the square-ring metal layer and the lower metal layer; the material of the dielectric layer is Taconic RF-35, the dielectric constant is 3.5, and the thickness of the dielectric layer is 1.524 mm;

[0008] Four triangular metal patches of different sizes are also provided on the upper surface of the dielectric substrate. Each side of the square-ring metal layer is connected to a triangular metal patch, and one side of the triangular metal patch is connected to the side of the square-ring metal layer; the four triangular metal patches are all located inside the ring of the square-ring metal layer;

[0009] Two concentric circular CSRRs are etched on the apex of the triangular metal patch away from the square ring metal layer.

[0010] The triangular metal patch is a quarter substrate integrated waveguide.

[0011] To achieve miniaturization and control the operating frequencies of the four triangular metal patches, preferably, the triangular metal patch is an isosceles triangular metal patch.

[0012] To improve the sensitivity of the sensor and enhance the electric field accumulation effect, preferably, the notches of the two concentric CSRRs are opposite.

[0013] To further improve the detection accuracy, preferably, the long side of the triangular metal patch is connected to the square ring metal layer.

[0014] To facilitate detection, preferably, a groove is provided on the side of the triangular metal patch connected to the square ring metal layer, and an opening corresponding to the groove is provided on the square ring metal layer; a microstrip line connected to the triangular metal patch is provided in the groove, and the microstrip line passes through the opening and is connected to an SMA connector.

[0015] To make the current complete the loop through a longer path, preferably, the width of the opening and the groove is the same, and the microstrip line is not connected to the two sides of the groove, forming a slot.

[0016] To facilitate the detection of samples, preferably, a sample frame is further provided on the dielectric substrate, and the square ring metal layer is located within the sample frame.

[0017] A method for measurement using the above-mentioned CSRR-based quarter substrate integrated waveguide sensor includes the following steps:

[0018] (1) Connect the sensor to a vector network analyzer (VNA) using a standard coaxial cable with an SMA connector 10, add the solid sample material into the sample frame, and the sensitivity of the sensor is:

[0019]

[0020] ε is the relative permittivity of the solid sample, f ε is the resonance frequency when the solid sample is loaded, f0 is the resonance frequency of the sensor when unloaded, and Δε represents the difference in permittivity between the unloaded and loaded states;

[0021] (2) Place samples with four different permittivities into the sensor for measurement respectively, establish the frequency change curves of four poles, and obtain the frequency-permittivity curve formula of the cavities corresponding to the four triangular metal patches:

[0022] ε r1= 4.8651f1 3 - 38.413f1 2 + 92.315f1 - 61.384(2)

[0023] ε r2 = - 8.3906f2 3 + 79.953f2 2 - 260.61f2 + 291.24(3)

[0024] ε r3 = - 1.0901f3 3 + 14.517f3 2 - 68.985f3 + 114.89(4)

[0025] ε r4 = 3.459f4 3 - 36.616f4 2 + 121.24f4 - 118.42(5)

[0026] ε r1 ,ε r2 ,ε r3 ,ε r4 are the dielectric constant values of four different cavities; f1, f2, f3, f4 are the resonance frequencies of four different cavities respectively;

[0027] (3) Weight the above data to obtain the actual dielectric constant value ε r ;

[0028]

[0029] where S Σ = S1 + S2 + S3 + S4; S1, S2, S3, S4 are the sensitivities of the sensor corresponding to four samples with different dielectric constants respectively; S Σ is the sum of the sensitivities of the four cavities.

[0030] The sensor of the present invention has a novel design. Four triangular metal patches with different sizes are used as four quarter-substrate integrated waveguides. Four QMSIW cavities with different sizes are all loaded with improved CSRR and are separately excited by four feeders to generate four independent poles, realizing simultaneous multi-band operation, improving efficiency and reducing errors and losses. By using QMSIW, the size of the sensor is reduced by about 75%. Inserting circular complementary split-ring resonator (CSRR) slots on each QMSIW cavity further reduces the size. It has the characteristics of small volume, easy integration, high flexibility, low loss, and high sensitivity, and can effectively construct a high electric field environment and improve sensitivity.

[0031] The sensor of the present invention was fabricated and tested. The measurement results show good correlation with the simulation results, proving the reliability of the measured values of the sensor. On the basis of ensuring high sensitivity, the four-pole sensor can measure the dielectric constant of solid materials quickly and with low error, providing great help for daily life or industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic structural diagram of the present invention;

[0033] Figure 2 is a schematic cross-sectional diagram of the present invention;

[0034] Figure 3 is a schematic structural diagram of the square ring metal layer of the present invention;

[0035] Figure 4 is a schematic structural diagram of the triangular metal patch of the present invention;

[0036] Figure 5 is a diagram showing the influence of the number of etched split rings on the frequency;

[0037] Figure 6 is a diagram showing the influence of the thickness of the sample to be measured on the sensor of the present invention, where (a), (b), (c), and (d) are diagrams showing the influence of the sample thickness on the frequencies of the four quarter-substrate integrated waveguides respectively;

[0038] Figure 7 is a diagram showing the influence of the shape of the sample to be measured on the sensor of the present invention;

[0039] Figure 8 are a physical diagram and an experimental setup diagram of the sensor of the present invention, where (a) is the physical diagram of the sensor of the present invention and (b) is the experimental setup diagram;

[0040] Figure 9 is a comparison diagram of the dielectric constant simulation of pulverized coal and the measurement results of the sensor of the present invention, where (a) is the result comparison diagram of dry pulverized coal; (b) is the result comparison diagram of wet pulverized coal;

[0041] In the figures: 1, dielectric substrate; 2, square ring metal layer; 3, lower metal layer; 4, metal hole; 5, triangular metal patch; 6, CSRR; 7, groove; 8, opening; 9, microstrip line; 10, SMA connector; 11, sample frame. DETAILED DESCRIPTION OF THE INVENTION

[0042] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0043] It should be noted that all the directional indications in the embodiments of the present application are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0044] In the present application, unless otherwise clearly defined and limited, the terms "connection", "fixation", etc. shall be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the connection inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0045] In addition, in the present application, the descriptions such as "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present application.

[0046] As Figure 1 、 2 As shown in Figures 3 and 4, a quarter substrate integrated waveguide sensor based on CSRR includes a dielectric substrate 1. A square ring metal layer 2 is provided on the upper surface of the dielectric substrate 1, and a lower metal layer 3 is provided on the lower surface of the dielectric substrate 1. A row of metal holes 4 are evenly distributed circumferentially on the square ring metal layer 2, and the metal holes 4 penetrate through the square ring metal layer 2 and the lower metal layer 3.

[0047] On the upper surface of the dielectric substrate 1, there are also four triangular metal patches 5 with different sizes. Each side of the square ring metal layer 2 is connected to a triangular metal patch 5. One side of the triangular metal patch 5 is connected to the side of the square ring metal layer 2. The four triangular metal patches 5 are all located inside the ring of the square ring metal layer 2. The triangular metal patch 5 is an isosceles triangular metal patch, and its long side is connected to the square ring metal layer 2.

[0048] On the vertex angle of the triangular metal patch 5 far from the square ring metal layer 2, two concentric circular CSRRs 6 are etched. The notches of the two concentric CSRRs 6 are opposite, and the notch of one CSRR faces the vertex angle of the triangular metal patch 5.

[0049] The triangular metal patch is a quarter substrate integrated waveguide.

[0050] On the side of the triangular metal patch 5 connected to the square ring metal layer 2, there is a groove 7. On the square ring metal layer 2 corresponding to the groove 7, there is an opening 8. Inside the groove 7, there is a microstrip line 9 connected to the triangular metal patch 5. The microstrip line passes through the opening 8 and is connected to the SMA connector 10. The widths of the opening and the groove are the same. The microstrip line 9 is not connected to the two sides of the groove 7, forming a slot.

[0051] On the dielectric substrate 1, there is also a sample frame 11, and the square ring metal layer 2 is located inside the sample frame 11.

[0052] The method for measurement using the above CSRR-based quarter substrate integrated waveguide sensor includes the following steps:

[0053] (1) Connect the sensor to a vector network analyzer (VNA) using a standard coaxial cable for the SMA connector 10. Add the solid sample material into the sample frame. The sensitivity of the sensor is:

[0054]

[0055] ε is the relative permittivity of the solid sample, f ε is the resonance frequency when the solid sample is loaded, f0 is the resonance frequency of the sensor when it is unloaded, and Δε represents the difference in permittivity between the unloaded and loaded states.

[0056] (2) Put four samples with different permittivities into the sensor for measurement respectively, establish the frequency change curves of four poles, and obtain the frequency and permittivity curve formula of the cavities corresponding to the four triangular metal patches:

[0057] ε r1 = 4.8651f1 3 - 38.413f1 2+92.315f1 - 61.384(2)

[0058] ε r2 = -8.3906f2 3 +79.953f2 2 -260.61f2 + 291.24(3)

[0059] ε r3 = -1.0901f3 3 +14.517f3 2 -68.985f3 + 114.89(4)

[0060] ε r4 = 3.459f4 3 -36.616f4 2 +121.24f4 - 118.42(5)

[0061] ε r1 ε r2 ε r3 ε r4 are the dielectric constant values of four different cavities; f1, f2, f3, f4 are the resonance frequencies of four different cavities respectively;

[0062] (3) Weight the above data to obtain the actual dielectric constant value ε r ;

[0063]

[0064] where S Σ = S1 + S2 + S3 + S4; S1, S2, S3, S4 are the sensitivities of the sensor corresponding to four samples with different dielectric constants respectively; S Σ is the sum of the sensitivities of the four cavities.

[0065] In the present invention, the operating frequencies of the four triangular metal patches are 3.12 GHz, 3.4 GHz, 4.2 GHz, and 4.4 GHz respectively; two concentric CSRRs 6 are arranged at the apex angles of the triangular metal patches, which can improve the sensitivity and accuracy of the sensor. Figure 4The figure shows the influence of one split ring resonator and two split ring resonators at the apex of a triangular metal patch on frequency. It can be seen from the figure that etching the CSRR structure can reduce the frequency, especially the nested CSRR structure has the lowest resonant frequency. After loading the double-ring split ring resonator, the current forms a magnetic field along the path of the curved ring, acting on the capacitance between the two split rings, causing the circuit to resonate. At this time, a large amount of energy is stored in the curved ring structure. Therefore, the combination of a quarter substrate integrated waveguide and the CSRR structure can effectively enhance the electric field strength, reduce the frequency, and reduce the size. At the same time, by adjusting the relevant parameters of the cavity and the CSRR, the sensor structure is further optimized to improve the sensitivity and accuracy, and achieve frequency-independent adjustment. Considering the frequency offset and the sharpness of the curve comprehensively, the radius differences of two concentric CSRRs in the four triangular metal patches are finally determined to be 1.65 mm, 1.65 mm, 0.7 mm, and 1.25 mm;

[0066] In the design of the present invention, the influence of the thickness of the sample on the sensor is fully considered. In order to study the influence of the sample thickness on the sensor performance, materials with the same dielectric constant but different thicknesses are selected for simulation on the electromagnetic simulation software. Within a certain range, the increase or decrease of the sample thickness will affect the accuracy of the dielectric constant measurement. Figure 5 It is the frequency change diagram under different thickness materials. The dielectric constant of the MUT is 3.5. As the thickness h increases, the four frequency points gradually shift to the low frequency, and the frequency offset Δf gradually increases. When the thickness h is 11 mm Figure 6 the offset of the high-frequency point in it is larger, and the curve end point is sharp. Therefore, the thickness of the measured object of the sensor of the present invention is 11 mm, that is, the thickness of the sample frame can be designed to be 11 mm; in addition, the present invention also studies the influence of the shape of the sample frame on the sensor. The same material is used to make a circular structure with a radius of 29 mm and a square structure with a side length of 44 mm respectively, so that it completely covers the area to be measured. As Figure 7 shown by the results, except for the slight deviation of the high-frequency point, the two resonant frequency distributions are basically the same. Compared with the circular sample frame, the reflection coefficient of the rectangular sample frame (especially S 11 、S 22 and S 33 ) is lower and sharper. Therefore, the present invention selects a 44×44 mm square material for the experiment, which not only saves materials but also ensures good results when measuring the dielectric constant.

[0067] In order to verify the operability and performance of the present invention, four 50Ω SMA connectors are welded to the sensor, and the sensor is connected to the VNA using a standard coaxial cable to record the transmission coefficient of the sample. In addition, before measurement, the VNA is calibrated using a calibration component ZV-Z135. Figure 8Shows the physical diagram of the sensor and the measurement device of the present invention; among them, the length and width of the sample frame are both 44 mm, the height is 11 mm, the wall thickness is 0.2 mm, and the relative dielectric constant is 3.1; the length and width of the square ring metal layer are both 43 mm; the triangular metal patches are all isosceles triangles, and the waist lengths of the four triangular metal patches are 22.1 mm, 20.5 mm, 16.71 mm, and 14.87 mm respectively; the frequencies of the four triangular metal patches are 3.12 GHz, 3.4 GHz, 4.2 GHz, and 4.4 GHz; the radius differences of the two concentric rings are 1.65 mm, 1.65 mm, 0.7 mm, and 1.25 mm. After adding the two concentric rings, the frequencies of the four triangular metal patches are 3.03 GHz, 3.21 GHz, 4.09 GHz, and 4.25 GHz.

[0068] To judge the moisture degree of the pulverized coal, first fill the container with dry pulverized coal (weight moisture content is 4%) and connect it to the VNA. According to the four measurement frequencies, substitute them into equations (2)(3)(4)(5) to obtain four actual dielectric constants, and then multiply them by the corresponding normalized sensitivities. As Figure 9 The measurement results show that the dielectric constant of dry pulverized coal is about 2.3, rather than the ideal 2.2. The reason is that the dielectric constant of pulverized coal is affected by various factors such as humidity, composition, and particle size. In this experiment, the pulverized coal particles used were not fine enough and there were still some small coal blocks mixed in, which made the dielectric constant value (ε r ) of dry pulverized coal about 2.3. The measurement result obtained by the sensor is (ε c ) 2.339. Due to the limitation of processing accuracy, small fluctuations and small deviations in amplitude may occur in the S curve, but its overall frequency band distribution is consistent with the simulation, which proves the high feasibility and accuracy of the sensor in the measurement process.

[0069] Use formula (7) to evaluate the accuracy of the sensor, compare the measurement result (ε c ) with the actual relative dielectric constant (ε r ). The small difference between them indicates the minimum error. It is calculated that the error value of this sensor is only 1.6%, and this error level is completely within the acceptable range, which fully proves the high precision and reliability of the sensor in measuring the dielectric constant.

[0070]

[0071] Subsequently, a few drops of water were added to the pulverized coal and stirred evenly, and the dielectric constant of the wet pulverized coal (weight moisture content is 25%) was measured. Based on the data of the four frequencies, it is calculated that the dielectric constant of the wet pulverized coal at this time is 3.45. As Figure 9(b) is the comparison between the simulation and the actual measurement results, and the results show that they are similar. Given the extremely small error in the measurement of dry pulverized coal, this provides strong evidence for the reliability of the dielectric properties of wet pulverized coal. Therefore, it can be clearly concluded that the dielectric constant of this wet pulverized coal is 3.5. In short, the sensor also demonstrates extremely high precision and reliability when measuring the dielectric constant of wet pulverized coal. Its measurement is highly consistent with the simulation in the overall frequency distribution, with low error, fully proving its applicability and accuracy under different pulverized coal states.

[0072] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0073] In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on what can be achieved by those of ordinary skill in the art. When the combination of technical solutions results in contradictions or cannot be achieved, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0074] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A quarter-chip integrated waveguide sensor based on CSRR, characterized in that: It comprises a dielectric substrate, wherein a square ring metal layer is provided on the upper surface of the dielectric substrate, a lower metal layer is provided on the lower surface of the dielectric substrate, a row of metal holes is evenly distributed in the circumferential direction of the square ring metal layer, and the metal holes penetrate the square ring metal layer and the lower metal layer; Four triangular metal patches of different sizes are also arranged on the upper surface of the dielectric substrate, each side of the square ring metal layer is connected to a triangular metal patch, one side of the triangular metal patch is connected to the side of the square ring metal layer; the four triangular metal patches are all located in the ring of the square ring metal layer; Two concentric annular CSRRs are etched on the top corners of the triangular metal patch away from the square ring metal layer.

2. A quarter-chip integrated waveguide sensor based on CSRR according to claim 1, characterized in that: The triangular metal patch is an isosceles triangle metal patch.

3. A quarter-chip integrated waveguide sensor based on CSRR according to claim 1, characterized in that: The notches of the two concentric CSRRs are opposite.

4. The CSRR-based quarter-chip integrated waveguide sensor according to claim 2, characterized in that: The long side of the triangular metal patch is connected to the square ring metal layer.

5. The CSRR-based quarter-chip integrated waveguide sensor according to claim 1, characterized in that: A groove is provided on the side where the triangular metal patch is connected to the square ring metal layer, and an opening is provided on the square ring metal layer corresponding to the groove; a microstrip line connected to the triangular metal patch is provided in the groove, and the microstrip line passes through the opening to connect to the SMA connector.

6. A CSRR-based quarter-chip integrated waveguide sensor according to claim 5, characterized in that: The opening and the groove have the same width, and the microstrip line is not connected to two sides of the groove.

7. The CSRR-based quarter-chip integrated waveguide sensor according to claim 1, characterized in that: A sample frame is also provided on the dielectric substrate, and the square ring metal layer is located in the sample frame.

8. The CSRR-based quarter-chip integrated waveguide sensor according to claim 1, characterized in that: The frequencies of the four triangular metal patches are 3.12 GHz, 3.4 GHz, 4.2 GHz, and 4.4 GHz, respectively; the radius differences of the two concentric rings are 1.65 mm, 1.65 mm, 0.7 mm, and 1.25 mm.

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