A planar microwave sensor with a loaded complementary curved ring resonator structure

Abstract

The present invention discloses a planar microwave sensor loaded with a complementary curved ring resonator structure, comprising a composite board, the composite board comprising a substrate, a copper-clad layer fixed on the bottom surface of the substrate, and a transmission line copper-clad layer fixed on the top surface of the substrate, a measurement area for placing a high-frequency board to be measured is arranged in the middle of the transmission line copper-clad layer, the measurement area is provided with a curved ring groove for forming an electric field, and a plurality of metal through holes for limiting energy leakage to the outside are symmetrically arranged on both sides of the measurement area. A planar microwave sensor loaded with a complementary curved ring resonator structure adopts the above structure, the measurement area is provided with a curved ring groove for forming an electric field, the electric field strength of the measurement area is effectively improved, and the provision of the metal through holes reduces the leakage of the transmission signal energy, so that it has higher sensitivity.

Description

Technical Field

[0001] The invention relates to the field of microwave measurement and sensing technology, and in particular to a planar microwave sensor with a loaded complementary curve ring resonator structure. Background Art

[0002] Dielectric constant is an important parameter that characterizes the electrical properties of dielectric materials. In microwave circuits, the size of the dielectric constant of the circuit substrate affects the transmission rate of the signal and also determines the characteristic impedance value of the circuit. Accurate measurement of the dielectric constant helps to achieve accurate modeling and design of electromagnetic systems. Traditional methods of measuring dielectric constants are limited by factors such as complex measurement devices and high detection costs, making the measurement process cumbersome and costly.

[0003] In recent years, microwave sensors have been widely used in biomedicine, concentration detection, solid and liquid quality detection and other fields due to the real-time, non-destructive and low-cost characteristics of microwave measurement. Many researchers choose to use the microwave planar resonance method to measure the dielectric constant of materials. The planar resonance method is simple to measure, easy to process and manufacture, and has high measurement accuracy. When the object to be measured is placed in the resonance area, the electric field in the resonance area will be disturbed, which will cause the displacement of the resonance frequency. The dielectric constant value of the object to be measured is obtained by the change of the resonance frequency.

[0004] Sreedevi P. Chakyar et al. proposed a microwave sensor using a split ring resonator (SRR) metamaterial structure to measure the dielectric constant of the material, but the measurement accuracy was not high. The literature Yeo J, Lee JI. Meander-Line Slot-Loaded High-Sensitivity Microstrip Patch Sensor Antenna for Relative Permittivity Measurement [J]. Sensors, 2019, 19 (21): 4660-4675. uses a high-sensitivity microstrip patch sensor with a loaded curved slot structure. Compared with the traditional rectangular patch structure, it has higher sensitivity, but the measurement sample size is larger. Therefore, sample miniaturization and high-precision measurement have become difficult problems that need to be solved by today's technology. Summary of the invention

[0005] The purpose of the present invention is to provide a planar microwave sensor with a loaded complementary curve ring resonator structure, which has higher sensitivity and can achieve the purpose of low-cost, fast and accurate measurement of material properties.

[0006] To achieve the above-mentioned purpose, the present invention provides a planar microwave sensor loaded with a complementary curved ring resonator structure, comprising a composite board, wherein the composite board comprises a substrate, a copper clad layer fixed on the bottom surface of the substrate, and a transmission line copper clad layer fixed on the top surface of the substrate, a measurement area for placing a high-frequency board to be measured is arranged in the middle of the transmission line copper clad layer, a curved ring groove for forming an electric field is opened in the measurement area, and a plurality of metal through holes for limiting energy leakage to the outside are symmetrically arranged on both sides of the measurement area.

[0007] Preferably, the curved ring groove includes a first annular groove, a second annular groove located on the inner side of the first annular groove, a third annular groove located on the inner side of the second annular groove, a first rectangular groove and a second rectangular groove, the first annular groove, the second annular groove and the third annular groove are all provided with notches, one end of the notch of the first annular groove is connected to one end of the notch of the second annular groove through the first rectangular groove, the other end of the notch of the second annular groove is connected to one end of the notch of the third annular groove through the second rectangular groove, the first rectangular groove and the second annular groove are arranged in parallel, and gaps are provided between the first annular groove and the second annular groove and between the second annular groove and the third annular groove.

[0008] Preferably, the gap width W of the first annular groove is c =1mm-2mm, the inter-ring width R0 of the first annular groove, the second annular groove and the third annular groove is =0.5mm-1.5mm, the distance between the outermost side of the first annular groove and the dot is R1=6mm-8mm, the distance between the outermost side of the second annular groove and the dot is R2=4mm-6mm, and the distance between the third annular groove and the dot is R3=2mm-4mm.

[0009] Preferably, both ends of the composite board are provided with SAM connectors for connecting to a vector network analyzer, and both ends of the transmission line on the transmission line copper cladding layer are respectively connected to the SAM connectors at both ends.

[0010] Preferably, the line width W of the transmission line P =4.2mm-4.4mm.

[0011] Preferably, the substrate is a Rogers 4350 plate, and the plurality of metal through holes penetrate the Rogers 4350 plate, the copper clad layer and the transmission line copper clad layer.

[0012] Preferably, the inner diameter of the metal through hole d = 0.8mm-1.2mm, the gap p between adjacent metal through holes is not greater than 2mm, and the length distance W of several metal through holes along the transmission direction of the copper clad layer of the transmission line is Siw =18.3mm-18.7mm.

[0013] Preferably, the side dimension of the top surface of the composite plate along the transmission direction is L=50mm-58mm, and the side dimension of the top surface of the composite plate perpendicular to the transmission direction is W=32mm-40mm.

[0014] Therefore, the present invention adopts a planar microwave sensor with a complementary curved ring resonator structure loaded with the above structure, a measurement area for placing the high-frequency board to be measured is provided in the middle of the copper-clad layer of the transmission line, and a curved ring groove for forming an electric field is provided in the measurement area, which effectively improves the electric field strength of the measurement area, and a plurality of metal through holes for limiting energy leakage to the outside are symmetrically provided on both sides of the measurement area, so as to have higher sensitivity. When materials with different dielectric constant values ​​are loaded into the measurement area, different resonant frequencies will be presented on the vector network analyzer connected by the SAM connector, and the resonant frequency will continue to decrease with the increase of the dielectric constant. The dielectric constant value of the material to be measured is obtained by the empirical relationship between the dielectric constant of the material and the resonant frequency. The measurement method has high sensitivity, and the test method is simple and fast, and has a high application prospect in the field of measuring dielectric properties of materials.

[0015] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the main structure of the sensor of the present invention;

[0017] Figure 2 It is a schematic diagram of the transmission line and copper cladding structure of the present invention;

[0018] Figure 3 This is a schematic diagram of the structural dimensions of the curved ring groove of the present invention;

[0019] Figure 4 This is a schematic diagram of the structure of the curved ring groove of the present invention;

[0020] Figure 5 It is the resonant frequency diagram of the sensor of the present invention when it is unloaded;

[0021] Figure 6 It is a resonant frequency diagram when the dielectric loss tangent tan value of the loading material of the present invention is 0-0.01;

[0022] Figure 7 This is a resonant frequency diagram when the dielectric constant of the loading material of the present invention is 1-10;

[0023] Figure 8 It is a fitting curve diagram of the dielectric constant of the loading material of the present invention and the resonant frequency of the sensor.

[0024] Reference numerals

[0025] 1. Transmission line; 2. Substrate; 3. Curved ring groove; 301. First annular groove; 302. Second annular groove; 303. Third annular groove; 304. First rectangular groove; 305. Second rectangular groove; 4. Metal through hole; 5. SMA connector; 6. Copper cladding layer. DETAILED DESCRIPTION

[0026] Example

[0027] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0028] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Figure 1 This is a schematic diagram of the main structure of the sensor of the present invention. Figure 2 It is a schematic diagram of the transmission line and copper cladding structure of the present invention, Figure 3 This is a schematic diagram of the structural dimensions of the curved ring groove of the present invention. Figure 4 The schematic diagram of the structure of the curved ring groove of the present invention is as follows: Figure 1-4As shown, a planar microwave sensor with a complementary curved ring resonator structure is provided, comprising a composite board, the composite board comprising a substrate 2, a copper clad layer 6 fixed on the bottom surface of the substrate 2, and a transmission line copper clad layer fixed on the top surface of the substrate 2, the substrate 2 is a Rogers 4350 plate material, which has excellent dielectric properties and is widely used in electronic circuit manufacturing and microwave device design, a transmission line 1 is arranged on the transmission line copper clad layer, the side dimension of the top surface of the composite board along the transmission direction is L=50mm-58mm, the side dimension of the top surface of the composite board perpendicular to the transmission direction is W=32mm-40mm, and the thickness of the composite board is 0.508mm.

[0031] A measuring area for placing the high-frequency board to be measured is provided in the middle of the copper-clad layer of the transmission line. The measuring area is etched with a curved ring groove 3 for forming an electric field. The curved ring groove 3 includes a first annular groove 301, a second annular groove 302 located inside the first annular groove 301, a third annular groove 303 located inside the second annular groove 302, a first rectangular groove 304 and a second rectangular groove 305. The first annular groove 301, the second annular groove 302 and the third annular groove 303 are all provided with a notch. One end of the notch of the first annular groove 301 is connected to one end of the notch of the second annular groove 302 through the first rectangular groove 304, and the other end of the notch of the second annular groove 302 is connected to one end of the notch of the third annular groove 303 through the second rectangular groove 305. The first rectangular groove 304 and the second annular groove 305 are arranged in parallel, so that the contact area between the sensor and the object to be measured is wider. Gaps are provided between the first annular groove 301 and the second annular groove 302 and between the second annular groove 302 and the third annular groove 303. The gap width W of the first annular groove 301 c =1mm-2mm, the inter-ring width R0 of the first annular groove 301, the second annular groove 302 and the third annular groove 303 is =0.5mm-1.5mm, the distance between the outermost side of the first annular groove 301 and the dot is R1=6mm-8mm, the distance between the outermost side of the second annular groove 302 and the dot is R2=4mm-6mm, and the distance between the third annular groove 303 and the dot is R3=2mm-4mm.

[0032] Several metal through holes 4 are symmetrically arranged on both sides of the measurement area to limit the leakage of energy to the outside. Several metal through holes 4 penetrate the Rogers4350 board, the copper clad layer 6 and the copper clad layer of the transmission line. The inner diameter d of the metal through hole 4 is 0.8mm-1.2mm, the gap p between adjacent metal through holes 4 is not greater than 2mm, and the length distance W of several metal through holes 4 along the transmission direction of the copper clad layer of the transmission line is Siw =18.5mm. The provision of the metal through hole 4 effectively reduces the energy leakage from the test area, making the field strength in the measurement area more concentrated, and improving the measurement effect and measurement sensitivity of the sensor.

[0033] Both ends of the composite board are provided with SAM connectors 5 for connecting to a vector network analyzer, and both ends of the transmission line 1 on the transmission line copper layer are connected to the SAM connectors 5 at both ends respectively. 21 Parameters and resonant frequency values, line width W of the transmission line P =4.3mm, used to match the sensor impedance.

[0034] The working process of this embodiment is as follows:

[0035] like Figure 5 It can be seen that the resonant frequency of the sensor when no test material is loaded is 3.51 GHz.

[0036] like Figure 6 It can be seen that when the dielectric constant value of the sensor loading material is 1-10, the corresponding resonant frequency value changes from 3.51GHz to 2.31GHz, and the total displacement is 1200MHz. It can be seen that the sensor has a high sensitivity when loaded with materials with different dielectric constant values.

[0037] like Figure 7 It can be seen that when the dielectric constant value of the loaded material is the same and the dielectric loss tangent value tan changes from 0-0.01, the resonant frequency of the sensor remains unchanged, but the S 21 It increases with the increase of tan value.

[0038] like Figure 6 It can be seen that the relationship between the dielectric constant of the material and the resonant frequency of the sensor is fitted into a curve. By fitting the dielectric constant value of the material with the corresponding resonant frequency, the empirical relationship between the dielectric constant and the resonant frequency of the sensor is obtained:

[0039] ε′=3.75(f-1) 2 -21.8(f-1)+32.16

[0040] Where ε′ is the dielectric constant and f is the resonant frequency.

[0041] like Figure 8 It can be seen that there is a very high degree of match between the test results and the empirical relationship, which well proves the feasibility of using this sensor to measure the dielectric constant of materials.

[0042] Therefore, the present invention adopts a planar microwave sensor with a complementary curved ring resonator structure of the above structure. Under the action of the transmission signal, an electric field is formed between the annular grooves of the copper-clad layer of the transmission line. At this time, the object to be tested is placed in the measurement area, and the resonant frequency of the object to be tested is obtained on the vector network analyzer. When materials with different dielectric constant values ​​are loaded into the measurement area, different resonant frequencies will be presented on the vector network analyzer. As the dielectric constant increases, the resonant frequency will continue to decrease. The dielectric constant value of the material to be tested is obtained according to the empirical relationship between the dielectric constant of the material and the resonant frequency. The measurement method has high sensitivity, simple and fast testing methods, and has a high application prospect in the field of measuring dielectric properties of materials.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A planar microwave sensor with a loaded complementary curved ring resonator structure, characterized in that: The composite board includes a substrate, a copper-clad layer fixed on the bottom surface of the substrate, and a transmission line copper-clad layer fixed on the top surface of the substrate, a measurement area for placing a high-frequency board to be measured is arranged in the middle of the transmission line copper-clad layer, a curved ring groove for forming an electric field is opened in the measurement area, and a plurality of metal through holes for limiting energy leakage to the outside are symmetrically arranged on both sides of the measurement area; The curved ring groove includes a first annular groove, a second annular groove located inside the first annular groove, a third annular groove located inside the second annular groove, a first rectangular groove and a second rectangular groove, the first annular groove, the second annular groove and the third annular groove are all provided with a notch, one end of the notch of the first annular groove is connected to one end of the notch of the second annular groove through the first rectangular groove, the other end of the notch of the second annular groove is connected to one end of the notch of the third annular groove through the second rectangular groove, the first rectangular groove and the second annular groove are arranged in parallel, and a gap is provided between the first annular groove and the second annular groove and between the second annular groove and the third annular groove; Both ends of the composite board are provided with SAM connectors for connecting to a vector network analyzer, and both ends of the transmission line on the transmission line copper cladding layer are respectively connected to the SAM connectors at both ends; the line width W of the transmission line P =4.2mm-4.4mm; the substrate is a Rogers4350 sheet, and a plurality of metal through holes penetrate the Rogers4350 sheet, the copper clad layer and the transmission line copper clad layer; the inner diameter of the metal through hole d=0.8mm-1.2mm, the gap p between adjacent metal through holes is not greater than 2mm, and the length distance W of the plurality of metal through holes along the transmission direction of the transmission line copper clad layer is Siw =18.3mm-18.7mm.

2. A planar microwave sensor with a loaded complementary curved ring resonator structure according to claim 1, characterized in that: The notch width W of the first annular groove c =1mm-2mm, the inter-ring width R0 of the first annular groove, the second annular groove and the third annular groove is =0.5mm-1.5mm, the distance between the outermost side of the first annular groove and the dot is R1=6mm-8mm, the distance between the outermost side of the second annular groove and the dot is R2=4mm-6mm, and the distance between the third annular groove and the dot is R3=2mm-4mm.

3. A planar microwave transmission device with a loaded complementary curved ring resonator structure according to claim 2 The sensor is characterized by: The side dimension of the top surface of the composite plate along the transmission direction is L=50mm-58mm. The side dimension of the top surface of the composite plate perpendicular to the transmission direction is W=32mm-40mm.

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