A microstrip antenna crack monitoring sensor with temperature self-compensation function

Abstract

The application discloses a microstrip antenna crack monitoring sensor with a temperature self-compensation function, which comprises a radiation patch, a dielectric substrate, a temperature compensation substrate and a metal ground plate; the radiation patch and the metal ground plate are made of a metal good conductor; the dielectric substrate and the temperature compensation substrate are made of insulating materials; the radiation patch is located at the uppermost layer of the sensor, the metal ground plate is located at the lowermost layer of the sensor, the dielectric substrate and the temperature compensation substrate are located at the middle part of the sensor, the dielectric substrate is located at the upper part, and the temperature compensation substrate is located at the lower part. The application overcomes the disadvantage that the crack monitoring of the traditional microstrip antenna sensor is unreliable under a multi-temperature environment, almost eliminates the influence of temperature on crack monitoring, and improves the monitoring reliability of the microstrip antenna sensor; compared with using a low-temperature-sensitivity substrate material to reduce the temperature influence, the temperature compensation method of the application has a lower cost; the selection of the double-layer substrate material is not limited, and the application of the sensor in multiple fields is possible.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal structure crack monitoring, and particularly relates to a microstrip antenna crack monitoring sensor with a temperature self-compensation function. BACKGROUND

[0002] Under the action of long-term alternating load, the crack formed at the weak part of the metal structure will continuously expand, which not only destroys the integrity of the metal structure, but also reduces the carrying capacity of the metal structure due to stress concentration at the crack part, and thus causes accidents such as structure fracture. Therefore, in order to ensure the working stability and safety of the metal structure and avoid major accidents, metal structure crack information monitoring is of great significance to structure health monitoring and regular maintenance.

[0003] As a new type of metal structure health monitoring sensor, the microstrip antenna sensor has the advantages of simple structure, light weight, easy conformation to the structure surface, suitable area arrangement and the like, and has attracted wide attention from many scholars. The principle is to detect the resonance frequency shift to detect the relevant parameters of the structure. At present, the monitoring of multiple parameters such as crack length, width, depth and direction of the metal structure has been realized, and the identification of the crack position can be realized through the design of the microstrip antenna array.

[0004] However, the temperature also has an impact on the resonance frequency of the microstrip antenna sensor, and the resonance frequency drift caused by the change will have a great influence on the identification accuracy of the crack (especially the micro crack). Seasonal changes, day and night temperature differences and other environmental changes also require the antenna sensor to maintain stable performance in multiple temperature environments when monitoring the crack. Therefore, the temperature compensation research of the microstrip antenna sensor has become an indispensable link in engineering practice. SUMMARY

[0005] Therefore, the application provides a microstrip antenna crack monitoring sensor with a temperature self-compensation function, which can accurately monitor the crack in multiple temperature environments, avoids the influence of the environmental temperature and improves the working reliability of the microstrip antenna sensor.

[0006] The microstrip antenna crack monitoring sensor with a temperature self-compensation function disclosed by the application comprises a radiation patch (1), a dielectric substrate (2), a temperature compensation substrate (3) and a metal ground plate (4). The radiation patch (1) and the metal ground plate (4) are made of a metal good conductor. The dielectric substrate (2) and the temperature compensation substrate (3) are made of an insulating material. The radiation patch (1) is located at the uppermost layer of the sensor, the metal ground plate (4) is located at the lowermost layer of the sensor, the dielectric substrate (2) and the temperature compensation substrate (3) are located in the middle part of the sensor, and the dielectric substrate (2) is located above the temperature compensation substrate (3).

[0007] Further, the temperature coefficient of dielectric constant of the dielectric substrate (2) is opposite in sign to the temperature coefficient of dielectric constant of the temperature compensation substrate (3), that is In the formula, ε1 is the relative dielectric constant of the dielectric substrate, ε2 is the relative dielectric constant of the temperature compensation substrate, and T is the temperature.

[0008] Further, the thermal expansion coefficients of the radiation patch (1), the dielectric substrate (2) and the temperature compensation substrate (3) are close in size, so as to eliminate the deformation or failure of the sensor caused by temperature.

[0009] Further, the related parameters of the dielectric substrate and the temperature compensation substrate satisfy the following relationship:

[0010]

[0011] In the formula, h1 is the thickness of the dielectric substrate, h2 is the thickness of the temperature compensation substrate, α1 is the thermal expansion coefficient of the dielectric substrate, α2 is the thermal expansion coefficient of the temperature compensation substrate, and αp is the thermal expansion coefficient of the radiation patch. ε1 ε2 T In the formula, h1 is the thickness of the dielectric substrate, h2 is the thickness of the temperature compensation substrate, α1 is the thermal expansion coefficient of the dielectric substrate, α2 is the thermal expansion coefficient of the temperature compensation substrate, and αp is the thermal expansion coefficient of the radiation patch.

[0012] Further, the size of the radiation patch is designed according to the required resonant frequency.

[0013] Further, the resonant frequency of the temperature compensation antenna sensor is calculated as:

[0014]

[0015] The present application has the following beneficial effects:

[0016] The present application overcomes the shortcomings of the conventional microstrip antenna sensor in the multiple temperature environment, almost eliminates the influence of temperature on crack monitoring, and improves the monitoring reliability of the microstrip antenna sensor; compared with using low temperature sensitive substrate material to reduce the temperature influence, the temperature compensation method of the present application has lower cost; the selection of the double-layer substrate material is not limited, which provides the possibility for the application of the sensor in multiple fields. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A microstrip antenna sensor structure with temperature self-compensation function;

[0018] Figure 2 Comparison diagram of the present application and the conventional antenna sensor;

[0019] Figure 3 Temperature self-compensation principle diagram of the microstrip antenna sensor;

[0020] ​​Figure 4 Temperature self-compensated microstrip antenna sensor resonant frequency comparison chart before and after compensation;

[0021] Figure 5 Crack monitoring, temperature self-compensated antenna sensor and traditional antenna sensor comparison chart.

[0022] Figure: 1 - radiation patch, 2 - dielectric substrate, 3 - temperature compensation substrate, 4 - metal ground plate, 5 - feed line, 6 - center crack along the length of the patch. DETAILED DESCRIPTION

[0023] The application will be further described below with reference to the accompanying drawings, but in no way limits the application, any transformation or replacement based on the teaching of the application belongs to the protection scope of the application.

[0024] The application provides a microstrip antenna sensor with temperature self-compensation function, which comprises a radiation patch 1, a dielectric substrate 2, a temperature compensation substrate 3 and a metal ground plate 4. The radiation patch is located at the uppermost layer of the sensor, the metal ground plate is located at the lowermost layer of the sensor, the dielectric substrate and the temperature compensation substrate are located in the middle part of the sensor, and the dielectric substrate is on the top and the temperature compensation substrate is on the bottom.

[0025] The temperature coefficients of the dielectric constants of the two substrates of the sensor are positive and negative, that is, with the increase of temperature, one of the dielectric constants increases and the other decreases. By reasonably selecting the substrate materials with opposite temperature coefficients and designing the thicknesses of the two substrates, the substrate with opposite temperature coefficient of dielectric constant can compensate for the change of the dielectric constant of the other substrate and the size of the radiation patch caused by temperature, so as to realize temperature compensation.

[0026] Due to the insertion of the temperature compensation substrate, the calculation of various parameters of the antenna sensor is changed compared with the traditional antenna sensor, so that the resonant frequency of the temperature compensation antenna sensor can be calculated as:

[0027]

[0028] Wherein,

[0029]

[0030]

[0031]

[0032] In the formula, f 10 represents the resonant frequency under TM 10 mode, ε e is the effective dielectric constant, c is the speed of light in vacuum, L erepresents the length of the current (in ideal, unstrained case, it is the same as the geometric length, width of the patch, respectively, when the length L and the width W of the radiating patch are taken, it corresponds to the resonant frequency f 10 and f 01 ), ΔL represents the line extension caused by the edge effect. ε eff is the equivalent dielectric constant of the double-layer substrate, ε1 and ε2 are the relative dielectric constants of the upper and lower substrates, respectively, h1 is the dielectric substrate thickness, and h2 is the temperature compensation substrate thickness.

[0033] When h << L and h << W, the effective dielectric constant ε e can be approximated as the equivalent dielectric constant ε eff of the double-layer substrate, i.e. ε e ≈ ε eff , and ΔL can be approximated as 0. Therefore, the formula for calculating the frequency can be simplified as:

[0034]

[0035] The frequency shift δf 10 of the sensor in the TM 10 mode can be represented by the dielectric constants ε1, ε2 of the two-layer substrate and the change in the length L of the radiating patch:

[0036]

[0037] wherein,

[0038]

[0039]

[0040]

[0041] Therefore, the antenna frequency shift δf 10 can be represented as:

[0042]

[0043] Because the dielectric constants ε1, ε2 of the two substrates and the length L of the radiating patch are all related to temperature, the above formula can be expressed as:

[0044]

[0045] wherein α ε1 represents the dielectric constant temperature coefficient of the dielectric substrate, α ε2 represents the dielectric constant temperature coefficient of the temperature compensation substrate, and α T represents the thermal expansion coefficient of the patch.

[0046] Temperature self-compensation of the sensor requires frequency shift δf 10 =0, that is:

[0047]

[0048] Due to α ε1 α ε2 and α T It is an inherent property of the material; that is, by controlling the relationship between the thicknesses h1 and h2 of the upper and lower matrix layers, the antenna frequency shift δf can be adjusted. 10 By maintaining a constant temperature, the sensor achieves self-compensation for temperature changes. Assuming the dielectric constant and thermal coefficient of the substrate material and the coefficient of thermal expansion of the patch material are isotropic, TM... 01 The same temperature self-compensation effect will be achieved in this mode.

[0049] Appendix Figure 3 Embodiments of the present invention are illustrated. Temperature affects the dimensions of the microstrip antenna sensor substrate and radiating patch, as well as the dielectric constant of the substrate, thereby affecting the resonant frequency of the sensor. To address this issue, reference is made to... Figure 2 and Figure 3 This invention achieves temperature self-compensation of the sensor by inserting a compensation matrix layer on top of the original matrix to change the equivalent dielectric constant temperature coefficient of the sensor matrix, thus forming a microstrip antenna sensor with temperature self-compensation function. The temperature compensation matrix has the same length and width as the original matrix, but the temperature coefficient of its dielectric constant has the opposite sign. The relationship between the thickness of the temperature compensation matrix and the thickness of the dielectric matrix is ​​calculated by the following formula:

[0050]

[0051] Where ε1 and ε2 are the relative permittivity of the original dielectric matrix and the temperature-compensated matrix, respectively, and α ε1 The temperature coefficient α represents the dielectric constant of the dielectric matrix. ε2 The temperature coefficient α represents the dielectric constant of the temperature-compensated matrix. T h1 represents the coefficient of thermal expansion of the patch, h2 represents the thickness of the dielectric substrate, and h3 represents the thickness of the temperature compensation substrate.

[0052] Then, the dimensional parameters of each structure of the sensor are optimized through simulation to achieve the best temperature compensation performance. Finally, the crack recognition performance of the designed sensor is simulated to prove its feasibility and complete the design of the temperature self-compensating antenna sensor.

[0053] As attached Figures 1-2 As shown, this sensor consists of a four-layer structure: an uppermost radiating patch, a lowermost metal ground plane, and two middle insulating substrates (an upper dielectric substrate and a lower temperature compensation substrate).

[0054] Example One

[0055] The material of the radiation patch 1 of the sensor is copper, and the size is designed as 50mm*36mm*0.035mm. The material of the dielectric substrate 2 of the sensor is FR4 laminate (dielectric constant is 4.4, and dielectric constant temperature coefficient is 160ppm / ℃), and the size is designed as 62mm*48mm*0.36mm.

[0056] Further, the material of the temperature compensation substrate 3 is RT / duroid 5880 laminate (dielectric constant is 2.2, and dielectric constant temperature coefficient is -125ppm / ℃), and the size is designed as 62mm*48mm*0.508mm. Thus, the base frequency of the designed antenna sensor is f 10 =1.7917GHz, and f 01 =2.4823GHz.

[0057] In order to excite the two working modes of the sensor, the sensor also needs to be fed. The present application uses the edge side feeding mode to feed the sensor. The material of the feed line 5 is copper, the width of the feed line is 1mm, the length is 6mm, and the position is at 1 / 4 of the patch.

[0058] In order to make the compensation effect more intuitive, a control group is also set. The antenna sensor of the control group is the same as the temperature compensation antenna sensor of the present application in size and condition except that the control group does not have a compensation substrate.

[0059] The sensor is fed by the feed line to work. By measuring the resonance frequency offset of the sensor at different temperatures, the influence of temperature on the base frequency of the sensor can be obtained.

[0060] As shown in the attached Figure 4 figure, taking the resonance frequency f 10 in the TM10 mode as an example. In the case without temperature compensation, the antenna frequency shift increases with the change of temperature and decreases. In the temperature range of 0℃-60℃, the maximum resonance frequency offset is -21.24MHz at 60℃, and the average frequency shift in this temperature range is 9.495MHz. By inserting a layer of temperature compensation substrate, the resonance frequency offset can be controlled in the range of -0.5 to 0.5MHz in the temperature range of 0℃-60℃, and the average frequency shift is reduced to 0.238MHz, which is reduced by 97.5% compared with the case without compensation.

[0061] Example Two

[0062] This example mainly verifies the crack monitoring effect of the temperature self-compensation antenna sensor. The size parameters of the sensor are the same as those in Example One.

[0063] For example, the length of the center crack 6 along the length direction of the patch is monitored, as shown in the attached Figure 5 It can be seen that, in the temperature environment of 0℃-60℃, the "crack length-resonant frequency" curve of the un-temperature-compensated antenna sensor shifts downward with the increase of temperature, while the "crack length-resonant frequency" curves of the temperature self-compensated antenna sensors almost coincide with each other, and the temperature compensation effect is good.

[0064] The present application has the following beneficial effects:

[0065] The present application overcomes the drawback of unreliable crack monitoring of the conventional microstrip antenna sensor in a multi-temperature environment, almost eliminates the influence of temperature on crack monitoring, and improves the monitoring reliability of the microstrip antenna sensor; compared with using a low-temperature-sensitivity matrix material to reduce the influence of temperature, the temperature compensation method of the present application has lower cost; the selection of the double-layer matrix material is not limited, which provides the possibility for the application of the sensor in many fields.

[0066] The word "preferred" is used herein as a term of art to denote features that can be expected to enhance the applicability or utility of an embodiment of the application. It is not intended, however, to convey a meaning of preferred or optimum over other aspects of the application. The use of the term "preferred" or "preferably" in the detailed description and claims of this application should not be interpreted as meaning that the features thus described are necessarily preferred or advantageous in all circumstances. The term "or" as used in a phrase such as "A or B" means an inclusive "or" rather than an exclusive "or". That is, unless specifically indicated otherwise, or apparent from context, "X employs A or B" is within the scope of "X employs A or B." That is, if X employs A; X employs B; or X employs both A and B, then "X employs A or B" is satisfied under any of the foregoing instances.

[0067] Moreover, although the present disclosure has been illustrated and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based on the foregoing description and illustrations. The present disclosure includes all such modifications and alterations and is limited only by the scope of the appended claims. In particular, with respect to the various functions performed by the various components (e.g., elements, etc.) described above, the terms (including a reference to a "means") used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations of the present disclosure. In addition, while a particular feature of the disclosure can have been disclosed with respect to only one of several implementations, such feature can be combined with one or other features of the other implementations as can be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "including", "includes", "having", "has", "containing", or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprising". The above description is that of current implementations of the application. Various alterations and changes can be made thereto without departing from the spirit and scope of the application as outlined in the claims appended hereto.

[0068] The various functional units in the embodiments of the present application can be integrated in one processing module, or each unit can exist physically, or multiple or more units can be integrated in one module. The integrated module can be realized in the form of hardware, or in the form of a software functional module. When the integrated module is realized in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer readable storage medium. The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc. The various devices or systems mentioned above can execute the storage method in the corresponding method embodiments.

[0069] In summary, the above embodiments are one embodiment of the present application, but the embodiments of the present application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made under the spirit and principles of the present application are equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A microstrip antenna crack monitoring sensor having a temperature self-compensation function, characterized by, The temperature compensation antenna sensor comprises a radiation patch (1), a dielectric substrate (2), a temperature compensation substrate (3) and a metal ground plate (4); the radiation patch (1) and the metal ground plate (4) are made of a metal good conductor; the dielectric substrate (2) and the temperature compensation substrate (3) are made of an insulating material; the radiation patch (1) is located at the uppermost layer of the sensor, the metal ground plate (4) is located at the lowermost layer of the sensor, the dielectric substrate (2) and the temperature compensation substrate (3) are located in the middle part of the sensor, the dielectric substrate (2) is located at the upper part and the temperature compensation substrate (3) is located at the lower part. The temperature coefficient of the dielectric constant of the dielectric base (2) is opposite in sign to the temperature coefficient of the dielectric constant of the temperature compensation base (3), i.e. where ε1 is the relative dielectric constant of the dielectric base, ε2 is the relative dielectric constant of the temperature compensation base, and T is the temperature. The related parameters of the dielectric substrate and the temperature compensation substrate satisfy the following relationship: where h1 is the thickness of the dielectric substrate, h2 is the thickness of the temperature compensation substrate, a ε1 is the thermal expansion coefficient of the dielectric substrate, a ε2 is the thermal expansion coefficient of the temperature compensation substrate, a T is the thermal expansion coefficient of the radiating patch, ε1 is the relative dielectric constant of the dielectric substrate, and ε2 is the relative dielectric constant of the temperature compensation substrate. 2.The microstrip antenna crack monitoring sensor with temperature self-compensation function according to claim 1, wherein, The thermal expansion coefficients of the radiation patch (1), the dielectric substrate (2) and the temperature compensation substrate (3) are close to each other, so as to eliminate the deformation or failure of the sensor caused by temperature. 3.The microstrip antenna crack monitoring sensor with temperature self-compensation function according to claim 1, wherein, The size of the radiation patch is designed according to the required resonant frequency.

4. The microstrip antenna crack monitoring sensor having a temperature self-compensation function according to claim 1, characterized in that, The formula of the resonant frequency of the temperature compensation antenna sensor is: where f 10 represents the resonance frequency in TM 10 mode, h1 is the thickness of the dielectric substrate, h2 is the thickness of the temperature compensation substrate, ε1 is the relative dielectric constant of the dielectric substrate, ε2 is the relative dielectric constant of the temperature compensation substrate, ε eff is the equivalent dielectric constant of the double-layer substrate, c is the speed of light in vacuum, and L is the length of the radiation patch.

Images