A quarter-chip integrated waveguide sensor based on CSRR

Abstract

The present invention discloses a quarter-substrate integrated waveguide sensor based on CSRR. The sensor comprises a dielectric substrate, a square ring metal layer formed on the upper surface of the dielectric substrate, and a lower metal layer formed on the lower surface of the dielectric substrate. The square ring metal layer is evenly distributed with a row of metal holes. Four triangular metal patches of varying sizes are also formed on the upper surface of the dielectric substrate, one connected to each edge of the square ring metal layer. Two concentric ring-shaped CSRRs are etched on the top corners of the triangular metal patches away from the square ring metal layer. The sensor has a novel design, generating four independent poles, enabling simultaneous multi-band operation, improving efficiency, and reducing errors and losses. Using QMSIW, the sensor's size is reduced by approximately 75%, while also offering compact size, ease of integration, high flexibility, low loss, and high sensitivity.

Description

Technical Field

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

[0002] In industry and everyday life, one of the key methods for identifying material types is the accurate measurement of their dielectric properties. In the radio frequency (RF) and microwave fields, the dielectric constant, as a core parameter of dielectric properties, is particularly important for characterizing material properties. Pulverized coal is often used as a fuel in industrial production and daily life. However, moisture or impurities can lead to incomplete combustion of pulverized coal, producing harmful substances. The rational use of pulverized coal not only optimizes its application but also mitigates its negative impact on the environment. Therefore, assessing its moisture content and composition by measuring its dielectric constant is crucial for ensuring its safe and efficient use. When a material sample is placed in a microwave resonant sensor, subtle perturbations in the electric field will cause changes in the sensor's transmission characteristics, manifesting as amplitude changes in the S-parameter curve or shifts in the resonant frequency. In recent years, numerous sensors based on the microwave resonance principle have been proposed and experimentally verified for measuring the dielectric constant of materials. Microstrip sensors offer advantages in size, cost, and design flexibility, but their performance in high-frequency applications may be inferior to substrate-integrated waveguide (SIW) sensors.

[0003] SIW structures combine the low loss of planar structures with the ease of integration of non-planar structures. They offer advantages such as compactness, versatility, high integration density, low insertion loss, and strong power handling capability, making them widely used in various microwave device designs. Han et al. proposed a SIW microwave sensor loaded with a complementary bent ring resonator for measuring the dielectric constant of substrate materials. Experimental results demonstrate the sensor's high sensitivity and high resolution. Solid-state dielectric constant measurement sensors based on IDE-ELC SIW resonators offer advantages such as low cost, non-invasiveness, and high sensitivity. However, miniaturization is difficult when using full-mode substrate integrated waveguides (FMSIWs). Prior art models include FMSIWs, smaller half-mode substrate integrated waveguides (HMSIWs), and even smaller quarter-mode substrate integrated waveguides (QMSIWs). Wu and Zhao proposed a microwave measurement system for the composite dielectric constant of liquid samples based on an improved HMSIW. This system combines a passive resonant sensor with RF circuitry, eliminating the need for expensive VNAs and reducing costs. However, the lack of a VNA results in significant errors. 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. Compared with HMSIW, the proposed QMSIW microwave resonant sensor has a compact waveguide structure, small size, and is easy to integrate and deploy.

[0004] Microwave planar sensors typically employ split ring resonators (SRRs) and CSRR structures. Ebrahimi et al. proposed a microwave sensor using a pair of SRRs. This sensor loads a pair of identical SRRs on either side of a microstrip line, using one of the SRRs as a differential measurement reference. This improves interference immunity. However, since the SRR structure must be coplanar with the microstrip line, miniaturization and high integration are difficult. As a new sensor resonant structure, CSRRs exhibit advantages in specific application scenarios, offering excellent performance, such as high sensitivity. They are widely used in various microwave fields, including sensors, filters, and antennas. Compared to SRRs, CSRRs do not need to be coplanar with the microstrip line, but are instead etched into the sensor's surface, making the sensor more compact. Existing literature has compared the effects of varying numbers of CSRRs on electric field strength, and experimental results show that the electric field strength increases with the number of rings. Inspired by this, we etched two nested split ring resonators into the QMSIW surface, significantly reducing the sensor size to 40×40 mm while improving sensitivity. 2 Prior art has proposed QMSIW sensors loaded with CSRRs. While QMSIW reduces device size while maintaining low loss and high efficiency, the introduction of CSRRs provides additional flexibility for frequency tuning and performance optimization, while further reducing device size. However, these sensors typically achieve high-sensitivity measurements at a single frequency point, making them susceptible to various external and system-internal influences, leading to increased errors. Currently, there are no widely reported reports on 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 provided on the upper surface of the dielectric substrate, a lower metal layer provided on the lower surface of the dielectric substrate, and a row of metal holes evenly distributed around the square ring metal layer. The metal holes penetrate the square ring metal layer and the lower metal layer. The dielectric layer is made of Taconic RF-35 with a dielectric constant of 3.5 and a thickness of 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 within the ring of the square ring metal layer.

[0009] The triangular metal patch is etched with two concentric ring-shaped CSRRs at the top corners away from the square ring metal layer.

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

[0011] In order to achieve miniaturization, the operating frequencies of the four triangular metal patches are controlled. Preferably, the triangular metal patches are isosceles triangular metal patches.

[0012] In order to improve the sensitivity of the sensor and enhance the electric field accumulation effect, preferably, the gaps of the two concentric CSRRs are opposite.

[0013] In order to further improve the accuracy of detection, 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 edge 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.

[0015] In order to allow the current to complete the loop through a longer path, preferably, the width of the opening and the groove are the same, and the microstrip line is not connected to both sides of the groove, forming a slot.

[0016] In order 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 in the sample frame.

[0017] The method for measuring using the CSRR-based quarter-substrate integrated waveguide sensor comprises 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 to the sample frame. The sensitivity of the sensor is:

[0019]

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

[0021] (2) Four samples with different dielectric constants were placed in the sensor for measurement, and the frequency change curves of the four poles were established. The frequency and dielectric constant curve formulas of the cavities corresponding to the four triangular metal patches were obtained:

[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] εr1, ​​εr2, εr3, εr4 are the dielectric constant values ​​of four different cavities respectively; f1, f2, f3, f4 are the resonant frequencies of four different cavities respectively;

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

[0028]

[0029] Among them S Σ =S1+S2+S3+S4; S1, S2, S3, S4 correspond to the sensitivity of the sensor when using four different dielectric constant samples; 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 of different sizes serve as four quarter-substrate integrated waveguides. Four QMSIW cavities of different sizes are all loaded with improved CSRRs and are separately excited using four feed lines to generate four independent poles, achieving simultaneous multi-band operation, improving efficiency and reducing errors and losses. The use of QMSIW reduces the size of the sensor by about 75%. The insertion of a circular complementary split resonator (CSRR) slot in each QMSIW cavity further reduces the size. The sensor has the characteristics of small size, easy integration, high flexibility, low loss, and high sensitivity. It can effectively construct a high electric field environment and improve sensitivity.

[0031] The sensor was fabricated and tested, and the measured results showed good correlation with simulation results, demonstrating the reliability of the sensor's measurements. While maintaining high sensitivity, the four-pole sensor can quickly and accurately measure the dielectric constant of solid materials with low error, providing significant benefits for both daily life and industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0036] Figure 5 This is a graph showing the effect of the number of etched split rings on frequency;

[0037] Figure 6 Graphs showing the effect of the thickness of the sample to be tested on the sensor of the present invention, where (a), (b), (c), and (d) are graphs showing the effect of the sample thickness on the frequency of four quarter-substrate integrated waveguides, respectively;

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

[0039] Figure 8 Figures 1 and 2 are a physical diagram of the sensor of the present invention and a diagram of the experimental device, wherein (a) is a physical diagram of the sensor of the present invention and (b) is a diagram of the experimental device;

[0040] Figure 9 The following are comparison diagrams of the dielectric constant simulation of coal powder and the measurement results of the sensor of the present invention, wherein (a) is the comparison diagram of the results of dry coal powder; (b) is the comparison diagram of the results of wet coal powder;

[0041] In the figure: 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

[0042] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

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

[0044] In this application, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal connection of two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0045] In addition, the descriptions of "first", "second", etc. in this application are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0046] like Figure 1 、 2 , 3 and 4 show a quarter-substrate integrated waveguide sensor based on CSRR, comprising a dielectric substrate 1, a square ring metal layer 2 provided on the upper surface of the dielectric substrate 1, a lower metal layer 3 provided on the lower surface of the dielectric substrate 1, a row of metal holes 4 uniformly distributed circumferentially on the square ring metal layer 2, and the metal holes 4 penetrate the square ring metal layer 2 and the lower metal layer 3;

[0047] Four triangular metal patches 5 of different sizes are also provided on the upper surface of the dielectric substrate 1. Each side of the square ring metal layer 2 is connected to a triangular metal patch 5, and 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 within the ring of the square ring metal layer 2. The triangular metal patches 5 are isosceles triangle metal patches, and their long sides are connected to the square ring metal layer 2.

[0048] Two concentric ring-shaped CSRRs 6 are etched on the top corner of the triangular metal patch 5 away from the square ring metal layer 2; the notches of the two concentric CSRRs 6 are opposite to each other, and the notch of one CSRR faces the top corner of the triangular metal patch 5;

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

[0050] A groove 7 is provided on the edge where the triangular metal patch 5 connects to the square ring metal layer 2. An opening 8 is provided on the square ring metal layer 2 corresponding to the groove 7. A microstrip line 9 is provided within the groove 7, connecting to the triangular metal patch 5. The microstrip line passes through the opening 8 and connects to the SMA connector 10. The opening and the groove have the same width, and the microstrip line 9 is not connected to either side of the groove 7, forming a slot.

[0051] A sample frame 11 is further provided on the dielectric substrate 1 , and the square ring metal layer 2 is located in the sample frame 11 .

[0052] The method for measuring using the CSRR-based quarter-substrate integrated waveguide sensor comprises the following steps:

[0053] (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 to the sample frame. The sensitivity of the sensor is:

[0054]

[0055] ε is the relative dielectric constant of the solid sample, f ε is the resonant frequency when the solid sample is loaded, f0 is the resonant frequency when the sensor is unloaded, and Δε represents the difference in dielectric constant between unloaded and loaded states;

[0056] (2) Four samples with different dielectric constants were placed in the sensor for measurement, and the frequency change curves of the four poles were established. The frequency and dielectric constant curve formulas of the cavities corresponding to the four triangular metal patches were obtained:

[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] εr1, ​​εr2, εr3, εr4 are the dielectric constant values ​​of four different cavities respectively; f1, f2, f3, f4 are the resonant frequencies of four different cavities respectively;

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

[0063]

[0064] Among them S Σ =S1+S2+S3+S4; S1, S2, S3, S4 correspond to the sensitivity of the sensor when using four different dielectric constant samples; S Σ is the sum of the sensitivities of the four cavities.

[0065] The operating frequencies of the four triangular metal patches in the present invention are 3.12 GHz, 3.4 GHz, 4.2 GHz, and 4.4 GHz respectively; two concentric CSRRs 6 are set at the top corners of the triangular metal patches to improve the sensitivity and accuracy of the sensor. Figure 4The figure shows the influence of one open ring and two open rings on the frequency at the top corner of the triangular metal patch; 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 open resonator, the current forms a magnetic field along the path of the curved ring, acting on the capacitance between the two open rings, causing the circuit to resonate. At this time, the curved ring structure stores a large amount of energy. Therefore, the combination of a quarter-substrate integrated waveguide and a CSRR structure can effectively enhance the electric field strength, reduce the frequency, and reduce the size. At the same time, the relevant parameters of the cavity and CSRR are adjusted to further optimize the sensor structure, improve sensitivity and accuracy, and realize independent frequency adjustment. Taking into account the frequency offset and the sharpness of the curve, the final value of the radius difference between the two concentric CSRRs in the four triangular metal patches is determined to be 1.65mm, 1.65mm, 0.7mm, and 1.25mm;

[0066] The design of this invention fully considers the impact of sample thickness on the sensor. To study the effect of sample thickness on sensor performance, materials with the same dielectric constant but different thicknesses were selected and simulated using electromagnetic simulation software. Within a certain range, increasing or decreasing sample thickness will affect the accuracy of the dielectric constant measurement. Figure 5 The frequency change diagram of different thickness materials is shown in Figure 2. The dielectric constant of MUT is 3.5. As the thickness h increases, the four frequency points gradually shift to low frequency, and the frequency offset Δf gradually increases. When the thickness h is 11mm, Figure 6 The offset of the high frequency point in the curve is large, and the endpoint of the curve is sharp. Therefore, the thickness of the object measured by the sensor of the present invention is 11mm, that is, the thickness of the sample frame can be designed to be 11mm. In addition, the present invention also studies the effect of the shape of the sample frame on the sensor. The same material is used to make a circular structure with a radius of 29mm and a square structure with a side length of 44mm, so that they can completely cover the area to be measured. Figure 7 The results show that, except for a slight deviation in 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 uses 44×44mm square materials for experiments, which not only saves materials but also ensures good results when measuring dielectric constant.

[0067] To verify the operability and performance of the present invention, four 50Ω SMA connectors were soldered to the sensor and connected to a VNA using a standard coaxial cable. The transmission coefficient of the sample was recorded. In addition, the VNA was calibrated using calibration component ZV-Z135 before measurement. Figure 8The figure shows the actual sensor and the measuring device of the present invention; the sample frame is 44 mm long and wide, 11 mm high, 0.2 mm thick, and has a relative dielectric constant of 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 difference between the two concentric rings is 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] In order to determine the moisture content of the coal powder, a container is first filled with dry coal powder (water content of 4% by weight) and connected to the VNA. According to the four measurement frequencies, the four actual dielectric constants are substituted into equations (2), (3), (4), and (5), and then multiplied by the corresponding normalized sensitivity. Figure 9 (a) The measurement results show that the dielectric constant of dry pulverized coal is approximately 2.3, rather than the ideal 2.2. This is because the dielectric constant of pulverized coal is affected by a combination of factors, including humidity, composition, and particle size. In this experiment, the pulverized coal particles used were not fine enough and contained some small coal lumps, which resulted in a larger dielectric constant value (ε r ) is about 2.3. The measurement result obtained by the sensor is (ε c )2.339. Due to limitations in machining precision, the S-curve may exhibit small fluctuations and deviations in amplitude, but its overall frequency band distribution remains consistent with the simulation, demonstrating the sensor's high feasibility and accuracy in measurement.

[0069] Equation (7) is used to evaluate the accuracy of the sensor and the measurement results (ε c ) and the actual relative dielectric constant (ε r ) were compared, and the slight difference between them indicated minimal error. The calculated error for this sensor was only 1.6%, which is well within the acceptable range and fully demonstrates the sensor's high accuracy and reliability in measuring dielectric constant.

[0070]

[0071] Afterwards, a few drops of water were added to the coal powder and stirred evenly. The dielectric constant of the wet coal powder (water content of 25% by weight) was measured. Based on the data of the four frequencies, the dielectric constant of the wet coal powder was calculated to be 3.45. Figure 9(b) shows a comparison between the simulation and actual measurement results, showing similarities. Given the minimal error in the dry pulverized coal measurement, this provides strong evidence for the reliability of the dielectric properties of the wet pulverized coal. Therefore, it can be clearly concluded that the dielectric constant of this wet pulverized coal is 3.5. In summary, the sensor also demonstrated extremely high accuracy and reliability in measuring the dielectric constant of wet pulverized coal. The overall frequency distribution of the measurement and simulation were highly consistent, with low error, fully demonstrating its applicability and accuracy across various pulverized coal conditions.

[0072] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present 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 any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0073] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0074] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A quarter-chip integrated waveguide sensor based on CSRR, characterized in that: The dielectric substrate comprises a square ring metal layer on the upper surface of the dielectric substrate, a lower metal layer on the lower surface of the dielectric substrate, a row of metal holes evenly distributed around 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 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 within the ring of the square ring metal layer. Two concentric ring-shaped CSRRs are etched on the top corners of the triangular metal patch away from the square ring metal layer.

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

3. The CSRR-based quarter-chip integrated waveguide sensor according to claim 1, wherein: The notches of the two concentric annular CSRRs are opposite to each other.

4. The CSRR-based quarter-chip integrated waveguide sensor according to claim 2, wherein: 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, wherein: 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. The 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 both 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 annular CSRRs are 1.65 mm, 1.65 mm, 0.7 mm, and 1.25 mm.

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