A microwave ice detection device and system based on capacitive coupling splitting ring

Abstract

The invention discloses a microwave ice detection device and system based on a capacitive coupling split ring, and relates to the technical field of ice detection. The invention provides a first split ring and a second split ring which are arranged opposite to each other, and a first microstrip line and a second microstrip line on the sides of the first split ring and the second split ring on a substrate. When in use, microwave signals with varying frequencies are loaded on the first split ring, the second split ring, the first microstrip line and the second microstrip line. The microwave signals are evenly scattered and reflected, transmitted and absorbed by a mixture of water, ice and air on the detection surface, and the reflected, transmitted and absorbed microwave signals are analyzed to determine ice information. The method is not affected by the external environment, and the accuracy of the detection result is greatly improved. The ice layer information is determined by measuring the reflected microwave information as a whole. Compared with optical, electromagnetic, mechanical and thermal measurement methods, the measurement stability is high and the method can be widely used.

Description

Technical Field

[0001] The present invention relates to the technical field of ice detection, and in particular to a microwave ice detection device and system based on a capacitive coupling splitting ring. Background Art

[0002] Icing is the phenomenon that water droplets / water films freeze and accumulate on low-temperature surfaces in cold climates. It is affected by the surface properties of the icing location and external environmental conditions such as temperature and humidity. Ice accumulation is widely present in the fields of aerospace, energy and transportation, power communications, navigation and polar exploration, which is extremely harmful and can cause significant loss of life and property. In the aerospace field, when water droplets come into contact with the exposed surface of an aircraft, atmospheric icing is very likely to occur, which is particularly dangerous for aircraft because the presence of ice can affect the aerodynamic properties of the flight surface, resulting in adverse effects including increased drag, reduced lift, faster stall speed, increased fuel consumption, etc., and sometimes even catastrophic flight accidents. In the energy and transportation sectors, ice accumulation reduces the efficiency of wind turbines by changing their aerodynamic shape, leading to increased energy loss. In the electric power and communications sector, when ice accumulates on power or communication lines, it may cause line interruptions, disrupting the normal operation of the energy sector. Ice on the antenna cover of the base station will distort the phase of the transmitted signal, increase its transmission loss, and reduce system performance. In the fields of navigation and polar scientific research, sea fog and waves will cause the deck of the ship to freeze quickly at low temperatures. The rapid increase of ice above the deck will cause the center of gravity of the ship to increase, which may lead to instability and eventual capsizing. The development of ice detection technology can help avoid or reduce the hazards caused by ice.

[0003] At present, the ice thickness detection technology used mostly determines whether there is ice and the thickness of ice by measuring the optical, electromagnetic, mechanical, thermal and other properties of ice; some studies determine the ice state of the detection surface by performing image recognition on the detection surface, but due to the small color difference between water, ice and air in image recognition, there is a large deviation; some studies are based on the photoelectric voltage effect, fitting the mathematical relationship between ice thickness and photoelectric voltage to determine ice thickness information, but this method requires the sensor to be embedded in the water or ice on the detection surface, which limits its application in some aspects; some studies perform ice thickness detection based on electromagnetism, and determine ice information by measuring the resistance of ice and air, but this method is only limited to detection at fixed positions; some studies perform ice thickness detection based on mechanics, and determine ice thickness by the mass of ice or water on the device, but it is highly affected by the environment and the accuracy will be greatly reduced.

[0004] Therefore, when ice detection is currently performed using optical, electromagnetic, mechanical, and thermal properties, the detection results are greatly affected by the environment during measurement, so the accuracy of the detection results in ice detection is low and it is difficult to be widely used. Summary of the invention

[0005] The embodiment of the present invention provides a microwave ice detection device and system based on a capacitive coupling splitting ring, which can solve the problem in the prior art that when ice detection is performed through optical, electromagnetic, mechanical and thermal characteristics, the detection results are greatly affected by the environment during measurement, resulting in low accuracy of the detection results in ice detection.

[0006] The embodiment of the present invention provides a microwave ice detection device based on a capacitive coupling splitting ring, comprising a microwave signal controller, wherein the microwave signal controller is communicatively connected to a microwave resonant sensor;

[0007] The microwave resonant sensor comprises a substrate arranged on the top surface of a shielding metal plate, and a copper foil is etched on the top surface of the substrate;

[0008] The copper foil includes two first cleavage rings and a second cleavage ring that are arranged opposite to each other, and the openings of the first cleavage ring and the second cleavage ring are arranged opposite to each other; a first microstrip line is arranged on the side of the first cleavage ring, and the first microstrip line extends to the edge of the substrate; a second microstrip line is arranged on the side of the second cleavage ring, and the second microstrip line extends to the edge of the substrate;

[0009] When the surface of the microwave resonant sensor is frozen, the microwave signal controller sends a microwave signal with a changing frequency to the copper foil, and the first splitting ring and the second splitting ring send microwave signals to the mixture on the surface of the microwave resonant sensor. After the microwave signal is reflected, transmitted and absorbed by the mixture, a measurement signal is formed.

[0010] After the measurement signal is transmitted to the microwave signal controller, the microwave signal controller obtains the resonance amplitude and the resonance frequency in the measurement signal, and obtains ice thickness information according to the resonance amplitude and the resonance frequency.

[0011] Preferably, a first signal interface is provided at the end of the first microstrip line, and a second signal interface is provided at the end of the second microstrip line;

[0012] The first signal interface is connected to an input port on the microwave signal controller, and the second signal interface is connected to an output port on the microwave signal controller.

[0013] Preferably, the microwave resonant sensor, the shielding metal plate and the microwave signal controller are sequentially assembled and arranged in an ice thickness detector housing, and the ice thickness detector housing is installed on the surface of the icing-prone equipment.

[0014] Preferably, a plurality of power line holes are provided on the side wall of the ice thickness detector housing;

[0015] A power line is arranged in one of the power line holes, and the power line is connected to the microwave signal controller;

[0016] A signal transmission line is arranged in another of the power line holes, and the signal transmission line is connected to the microwave signal controller.

[0017] Preferably, the microwave signal controller embeds the device on a circuit board through a printed circuit board, and the formed circuit board can be installed in a protective shell or arranged separately outside the device.

[0018] The embodiment of the present invention further provides a microwave ice detection system based on a capacitive coupling splitting ring, including the above-mentioned microwave ice detection device based on a capacitive coupling splitting ring, and further comprising:

[0019] A temperature sensor, wherein the temperature sensor is embedded in the microwave signal controller, one end of the temperature sensor is connected to the transformer on the microwave signal controller, and the other end of the temperature sensor is connected to the processor on the microwave signal controller, and the temperature sensor is used to measure the external environment temperature;

[0020] A wave source, which is embedded in the microwave signal controller and connected to a transformer and a processor on the microwave signal controller, and is used to emit a microwave signal with constant or variable power;

[0021] A transmission signal receiver, the transmission signal receiver is embedded in the microwave signal controller, one end of the transmission signal receiver is connected to the processor on the microwave signal controller, and the other end is connected to the input port on the microwave signal controller, and the transmission signal receiver is used to introduce the measurement signal on the microwave resonant sensor;

[0022] A reflected signal receiver, wherein the reflected signal receiver is embedded in the microwave signal controller, one end of which is connected to the processor on the microwave signal controller, and the other end is connected to the output port on the microwave signal controller. The reflected signal receiver is used to receive the microwave signal emitted by the wave source and input the microwave signal into the microwave resonant sensor through the output port.

[0023] Preferably, after the transformer converts 220V AC into 12V DC, the DC drives the wave source to emit a microwave signal with constant or variable power, which is transmitted to the output port through the reflection signal receiver and transmitted to the microwave resonance sensor through the second signal interface to detect ice thickness information;

[0024] The detection signal is transmitted to the input port through the first signal interface, and then transmitted to the processor through the transmission signal receiver. The detection signal is then comprehensively analyzed with the reflected signal and the wave source signal in the reflection signal receiver to obtain microwave scattering parameters, and ice thickness information is obtained through the microwave scattering parameters.

[0025] The embodiment of the present invention provides a microwave ice detection device and system based on a capacitive coupling splitting ring. Compared with the prior art, the beneficial effects thereof are as follows:

[0026] The present invention arranges a first split ring and a second split ring on a substrate, and a first microstrip line and a second microstrip line on the sides of the first split ring and the second split ring. When in use, microwave signals with varying frequencies are loaded on the first split ring, the second split ring, the first microstrip line and the second microstrip line. The microwave signals are evenly scattered and reflected, transmitted and absorbed by a mixture of water, ice and air on the detection surface. The reflected, transmitted and absorbed microwave signals are analyzed to determine icing information. This method is not affected by the external environment, and the accuracy of the detection result is greatly improved. The ice layer information is determined by measuring the reflected microwave information as a whole. Compared with optical, electromagnetic, mechanical and thermal measurement methods, the measurement stability is high and can be widely used. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the overall three-dimensional model structure of a microwave ice-probing device based on a capacitively coupled splitting ring provided in an embodiment of the present invention;

[0028] Figure 2 A control sensing schematic diagram of a microwave ice detection device and system based on a capacitive coupling splitting ring provided in an embodiment of the present invention; (a) is a schematic diagram of a microwave signal controller; (b) is a schematic diagram of a microwave resonant sensor structure;

[0029] Figure 3 A schematic diagram of an equivalent circuit of a microwave resonant sensor of a microwave ice detection device and system based on a capacitively coupled splitting ring provided in an embodiment of the present invention;

[0030] Figure 4 A capacitive coupling split ring sensor of a microwave ice detection device and system based on a capacitive coupling split ring provided in an embodiment of the present invention is provided under no-load S 21 Schematic diagram of parameter changes;

[0031] Figure 5 A schematic diagram of the variation of the relative dielectric constant of a microwave ice detection device and system based on a capacitive coupling splitting ring with ice thickness provided in an embodiment of the present invention;

[0032] Figure 6 A schematic diagram of the change of the resonant frequency of a microwave ice detection device and system based on a capacitive coupling splitting ring with ice thickness provided in an embodiment of the present invention;

[0033] Figure 7A schematic diagram of the variation of the resonance amplitude of a microwave ice detection device and system based on a capacitive coupling splitting ring with ice thickness provided in an embodiment of the present invention;

[0034] Figure 8 A schematic plan view of a detection sensor of a microwave ice detection device based on a capacitively coupled splitting ring provided in an embodiment of the present invention;

[0035] Fig. 9 A microwave ice detection device and system based on a capacitive coupling splitting ring provided in an embodiment of the present invention S 21 Schematic diagram of the parameter variation curve with microwave frequency from 1 to 6 GHz;

[0036] Fig.10 A schematic diagram of a curve showing a change in the first resonance peak of a microwave ice-probing device and system at 3.4 to 4.0 GHz based on a capacitively coupled splitting ring provided in an embodiment of the present invention;

[0037] Fig.11 A schematic diagram of a curve showing changes in the resonant frequency of a microwave ice-probing device and system based on a capacitively coupled splitting ring as a function of ice thickness provided in an embodiment of the present invention;

[0038] Fig.12 A schematic diagram of a curve showing the variation of the resonance amplitude of a microwave ice detection device and system with ice thickness based on a capacitively coupled splitting ring provided in an embodiment of the present invention.

[0039] Wherein: 1. microwave resonant sensor, 101. substrate, 102. SMA connector, 1021. first signal interface, 1022. second signal interface, 103. copper foil, 1031. first microstrip line, 1032. second microstrip line, 1041. first splitting ring, 1042. second splitting ring, 2. shielding metal plate, 3. microwave signal controller, 4. temperature sensor, 5. ice thickness detector housing, 6. ice thickness detection area, 7. power cord, 8. signal transmission line, 9. power cord hole, 301. transformer, 302. processor, 303. wave source, 304. reflection signal receiver, 305. output port, 306. output signal, 307. input signal, 308. input port, 309. transmission signal receiver. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0041] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, 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 orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0042] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0043] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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 an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0045] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0046] See also Figure 1-2 The embodiment of the present invention provides a microwave ice detection device, system and method based on a capacitive coupling split ring, including a microwave resonant sensor 1, a substrate 101, an SMA connector 102, a first signal interface 1021, a second signal interface 1022, a copper foil 103, a first microstrip line 1031, a second microstrip line 1032, a first split ring 1041, a second split ring 1042, a shielding metal plate 2, a microwave signal controller 3, a temperature sensor 4, an ice thickness detector housing 5, a power line 7, a signal transmission line 8 and a power line hole 9.

[0047] The microwave resonant sensor 1 is at the top of the entire device, and a shielding metal plate 2 and a microwave signal controller 3 are arranged below it in sequence. After the assembly is completed, it is placed in the ice thickness detector housing 5. The temperature sensor 4 is embedded in the microwave signal controller 3 and is close to the outer wall of the ice thickness detector housing 5 to measure the external environment temperature of the sensor; the microwave signal controller 3 and the microwave resonant sensor 1 can be connected through microwave signal transmission lines such as coaxial transmission lines and microstrip lines; the entire device is powered by a power cord 7 to maintain the operation of the sensor, and the detection results are transmitted to computers and other equipment through a signal transmission line 8; in the initial state, the microwave resonant sensor 1 has a smooth surface and is exposed to the environment. Once surface ice forms, it forms ice in the ice layer detection area 6 and will cover the surface of the microwave resonant sensor 1.

[0048] like Figure 2As shown in the figure, it is a controller and detection plane structure diagram of the capacitive coupled splitting ring microwave ice thickness detection sensor; wherein (a) shows the internal structure of the microwave signal controller 3, the power is introduced through the power line 7, and the 220V AC power is converted into 12V DC power through the transformer 301, which supplies power to the temperature sensor 4, the processor 302 and the wave source 303 respectively; when the sensor is working, the wave source 303 emits a microwave signal with constant power or variable frequency, which is transmitted to the output port 305 through the reflection signal receiver 304, and the emission signal of the wave source 303 and the related information of the reflection signal received by the reflection signal receiver 304 are also transmitted to the processor 302 for recording; the transmission signal receiver 309 transmits the microwave signal to the processor 302 through the reflection signal receiver 309. The input signal introduced by the input port 308 will be transmitted to the processor 302, and the reflected signal and the wave source signal will be analyzed to obtain the relevant microwave scattering parameters; (b) shows the structural diagram of the detection plane, the copper foil 103 is made on the substrate 101 through an etching process, and the SMA connector 102 is welded to the copper foil 103; the entire detection plane is connected to the sensor 3 through the SMA connector 102, specifically, the output port 305 and the input port 308 are respectively connected to the first signal interface 1021 and the second signal interface 1022; the copper foil 103 is etched on the substrate 101 to construct a capacitively coupled split ring structure, and the structural dimensions are marked in the figure by a, b, c, d, e, g and h.

[0049] Among them, the shielding metal plate 2 can be a metal material with good electrical conductivity such as a copper plate and a stainless steel plate; the shielding metal plate 2 can be a sheet-shaped, columnar or other structure; the controller 3 can be made in an integrated manner through printed circuit board technology, or it can be made by assembling and constructing various structures; the controller 3 can be placed in the ice thickness detector housing 5, or it can be independent of the entire detection equipment and exist as a separate module; the temperature sensor 4 can be a temperature measurement sensor such as a resistance thermometer or a thermocouple, and the specific selection of a small-sized thermocouple temperature sensor can significantly reduce the volume of the entire device; the ice thickness detector housing 5 can be a metal such as aluminum alloy, stainless steel, or a non-metallic material such as ceramics and plastics to protect the microwave signal controller 3 from damage caused by external influences; the power cord 7 can be connected to an external circuit to power on, or it can be simplified to a built-in power supply for the device; the signal transmission line 8 can transmit the detection results to the monitor via a wired connection or a wireless connection.

[0050] like Figure 3 The figure shows the equivalent circuit diagram of the capacitive-coupled split-ring microwave ice thickness detection sensor. Based on the lumped parameter method, the components in the capacitive-coupled split-ring circuit are abstracted into equivalent substrate components such as resistors, capacitors, and inductors, making it easy to perform circuit analysis and calculations. The total inductance of the equivalent circuit is L The inductance of the microstrip line L s and the inductance of the split ring L rThe inductance of the split ring is dominant, so the total inductance of the equivalent circuit is L The total capacitance of the equivalent circuit can be calculated approximately by the following formula: C The capacitance of the split ring in the equivalent circuit C r And the coupling capacitance between the open rings C m Composition, calculated by the following formula;

[0051]

[0052]

[0053]

[0054] in: μ 0 is the vacuum permeability, μ 0=4π×10 -7 N / A 2 ; a, b, c and d are Figure 2 Structural size parameters in ; is the real dielectric constant of the medium, and They are the vacuum dielectric constant and relative dielectric constant, the vacuum dielectric constant =8.85×10 -12 F / m.

[0055] When detecting frost, ice, or water, if the effective detection range of the sensor is not completely filled with the substance to be detected, the sensor is detecting a mixture of the substance to be detected and air. At this time, the dielectric constant of the mixture can be calculated using the dielectric constant exponential model, which is the following formula. This equation gives the complex dielectric constant of the mixture: ε mix Complex dielectric constants of its components ε i , and the relative volume fraction f i The functional relationship is:

[0056]

[0057] in: f i For the i Volume fraction of the component, Σ f i = 1; Exponent n is the empirical parameter of the model, and 0< n <1, when calculating the dielectric constant of a two-phase mixture, n = 1 / 3.

[0058] The impedance of the sensor equivalent circuit is related to the frequency of the electrical signal. When the impedance in the circuit is the smallest, the transmission loss of the electrical signal in the circuit is reduced to the minimum. The circuit state at this time is called circuit resonance, and the frequency of the electrical signal in the resonant state is the resonant frequency. S 21 The schematic diagram of the parameters changing with microwave frequency is shown in Figure 4 As shown, there will be two resonance peaks. S 21 The parameter values ​​and frequencies are respectively the first resonant frequency F 1. First resonance amplitude A 1. Second resonant frequency F 2 and the second resonance amplitude A 2; The first and second resonant frequencies of the capacitively coupled split ring in the resonant state can be calculated by the following formulas:

[0059]

[0060]

[0061] When microwaves pass through certain materials, reflection, transmission and absorption phenomena will occur; the microwave absorption power of the medium is expressed by the following formula, which shows that the microwave absorption power is proportional to the relative dielectric constant of the medium. ; The relative dielectric constant of air is about 1, the relative dielectric constant of ice is about 3.2, and the relative dielectric constant of water is about 80. Therefore, ice and water absorb microwaves more than air. When water or ice accumulates on the sensor surface, the transmission loss of microwave signals will increase. There are:

[0062]

[0063] in: F is the microwave frequency; E is the electric field strength of the microwave signal; tg δ is the tangent of the dielectric loss angle of the material to be tested; the first resonant frequency F 1 into the above formula, the microwave absorption power at the first resonant frequency is obtained as shown in the following formula; the microwave absorption power analysis at the second resonant frequency is similar to the analysis at the first resonant frequency; the increase in capacitance value will lead to a decrease in absorption power at the resonant frequency, while the increase in the relative dielectric constant of the material to be tested will lead to an increase in absorption power. Since the capacitance value is proportional to the relative dielectric constant, the increase in the relative dielectric constant of the material to be tested at the resonant frequency will lead to an increase in the loss during microwave transmission; the microwave absorption power at the first resonant frequency is:

[0064]

[0065] Microwave transmission scattering parameters of microwave resonant sensor S 21 The definition of is as follows, S 21 The larger the parameter, the smaller the signal transmission loss. Combined with the above analysis, it can be seen that at the resonant frequency, as the dielectric constant increases, the loss in the microwave transmission process increases, so S 21 The parameters will decrease with the increase of dielectric constant; microwave transmission scattering parameters S 21 is defined as:

[0066]

[0067] in: P 2 represents the microwave absorption power at the second resonant frequency.

[0068] When the measuring surface is not frozen, the sensor is exposed to the ambient air. At this time, the sensor detects the air within a certain range of the measuring surface. When the measuring surface is frozen, there are two substances, ice and air, on the upper part of the measuring surface. At this time, the detected ice-air mixture changes. Therefore, the most important physical property affecting the sensor detection result - the relative dielectric constant of the substance to be measured - changes. Figure 5 The figure shows a schematic diagram of the change of relative dielectric constant with ice thickness; the relative dielectric constant of air is about 1, and the relative dielectric constant of ice is about 3; therefore, according to the calculation formula of the relative dielectric constant of mixed substances, it can be obtained that the relative dielectric constant of the mixed substance is in the range between the relative dielectric constant of pure air 1 and the relative dielectric constant of ice 3. As the thickness of ice gradually increases, the volume fraction of ice in the mixture increases, and the relative dielectric constant of the mixture also gradually increases.

[0069] According to the above formula, as the ice thickness (ice volume fraction) increases, the relative dielectric constant of the ice-air mixture of the substance to be measured also gradually increases, which will cause the capacitance value in the equivalent circuit of the ice thickness detector to increase, thereby causing the resonant frequency to decrease; Figure 6 The figure shows a schematic diagram of the change of resonance frequency with ice volume fraction (ice thickness). When the ice thickness gradually increases, the resonance frequency corresponding to the two obvious resonance peaks of the ice thickness sensor F 1 and F 2 gradually decreases, and with the increase of thickness, the rate of decrease of the resonance frequency gradually decreases; at the same time, with the increase of thickness, the difference between the two resonance frequencies ΔF ( F 1- F 2) also gradually decreases; therefore, the two resonant frequencies and the difference of the ice thickness sensor show a monotonically decreasing trend with the ice thickness, so it has a good ability to reflect the ice thickness, which proves the reliability of this method in detecting ice thickness.

[0070] The loss tangent of air is 0, and the loss tangent of pure ice at -10°C is about 20. According to the second resonant frequency F 2, the microwave absorption power of the test material is proportional to the relative dielectric constant and loss tangent of the material; therefore, as the relative volume fraction of ice in the ice-air mixture increases, the microwave absorption power of the mixture increases, which also leads to a decrease in the energy transmitted to the input port 308 through the test material. According to the microwave absorption power formula of the medium, it can be seen that S 21 The reduction of parameters also leads to a reduction in the resonance amplitude; Figure 7 A schematic diagram showing the variation of the resonance amplitude as the volume fraction of ice decreases.

[0071] Specifically:

[0072] like Figure 8 As shown, the microwave resonant sensor 1, the shielding metal plate 2 and the microwave signal controller 3 are arranged in sequence from top to bottom and placed in the ice thickness detector housing 5 for protection. A power cord hole 9 for the power cord 7 is reserved on the ice thickness detector housing 5 for introducing power supply.

[0073] By using a vector network analyzer VNA and a computer to replace the built-in microwave signal controller 3. The influence of ice slices of different thicknesses placed on the sensor surface on the microwave transmission parameters was analyzed and tested; copper foil 103 was etched on the substrate 101 to construct a capacitive coupling split ring structure, and the structural dimensions of copper foil 103 were a = 10.5 mm, b = 6.5 mm, c = 1.7 mm, d = 1.0 mm, e = 0.8 mm, g = 1.4 mm, h = 4.4 mm; at the same time, the substrate size was a 60 mm rectangle with a thickness of 1.2 mm; the specific steps of ice thickness detection are as follows:

[0074] Step 1: Connect the input and output interfaces of the VNA vector network analyzer to the first signal interface 1021 and the second signal interface 1022 on the measurement plane through microwave transmission lines; the first signal interface 1021 and the second signal interface 1022 are connected using SMA connectors; the analyzer is connected to a PC through a signal line, and the PC is used to record and analyze microwave scattering parameters under different frequencies and ice thicknesses in real time.

[0075] Step 2: By placing a low-temperature heat exchanger under the sensor, the detection surface temperature is controlled to be below the freezing point to avoid deviation in the test results caused by melting of ice during the test.

[0076] Step 3: Place the prepared ice slices of different thicknesses on the sensor measurement plane. Record the real-time data recorded by the VNA vector analyzer within 2 minutes after placing the ice slices at a time interval of 5 seconds. At the same time, the recorded data results will also be displayed on the PC every 5 seconds.

[0077] Step 4: Extract the VNA vector analyzer recorded S 21 The peak value of the parameter variation curve with frequency is used to analyze the changes of the resonant frequency and resonant amplitude of the first resonant peak and the second resonant peak with ice thickness.

[0078] Step 5: Fit a double-peak ice thickness detection relationship through analysis results to simplify the ice detection process, that is, obtain ice thickness information through microwave detection results obtained through real-time detection.

[0079] like Fig. 9 and Fig.10 The following table shows the recorded data when the ice detection sensor was tested with different ice thicknesses. S 21 The variation of parameters with frequency; two obvious peaks appear at microwave frequencies of about 3 GHz and 3.7 GHz; the variation of the maximum peak in the range of 3.2 GHz to 4.0 GHz is shown in Fig.10 It can be seen that as the ice thickness gradually increases from 2.15 mm to 12.00 mm, the maximum resonance peak moves in the direction of decreasing frequency and decreasing amplitude; in addition, the second peak at 3 GHz also shows the same change trend; this phenomenon shows that the resonance frequency and resonance amplitude of the two resonance peaks have a monotonous change trend with the ice thickness, and a mathematical relationship related to the ice thickness can be constructed to achieve simple, fast and accurate ice thickness detection.

[0080] like Fig.11 As shown in the figure, it is a schematic diagram of the curve of the resonance frequency changing with the thickness of ice; the resonance frequencies of the two peak points at different ice thicknesses are extracted, and the resonance frequency changes with ice thickness are plotted. It can be seen that as the ice thickness gradually increases from 2.15 mm to 12.00 mm, the first resonance frequency and the second resonance frequency both show a trend of gradually decreasing. According to the experimental test results, polynomial fitting is performed, and the mathematical relationship between the first resonance frequency, the second resonance frequency and the ice thickness is constructed as follows:

[0081]

[0082]

[0083] like Fig.12As shown in the figure, the resonance amplitude of two peak points under different ice thicknesses is extracted from the curve of resonance amplitude variation with ice thickness, and the resonance amplitude variation with ice thickness is plotted. It can be seen that as the ice thickness gradually increases from 2.15 mm to 12.00 mm, the first resonance amplitude shows a trend of gradually decreasing, and the second resonance amplitude has unstable test results near 0.15 mm, but overall it also shows a trend of decreasing with increasing ice thickness. According to the experimental test results, polynomial fitting is performed to construct the mathematical relationship between the first resonance amplitude and the second resonance amplitude and ice thickness:

[0084]

[0085]

[0086] With the first peak resonance amplitude A 1 The calculated ice thickness is mainly based on the first resonant frequency. F 1. Second resonance amplitude A 2 and the second resonant frequency F 2 The calculated ice thickness results are used as reference, and the four calculated results are averaged to obtain accurate and stable ice thickness detection results.

[0087] Compared with ice detection methods such as optical method and mechanical method, the present invention has the advantages of simple principle and operation, high measurement stability, and great application potential.

[0088] The detection surface coupling mechanism of the present invention has various forms. It can couple two split ring structures in the form of capacitance, or couple multiple split rings in an array to obtain more resonance peaks, increase the ice thickness detection parameters of the sensor, and improve the accuracy and stability of ice thickness detection.

[0089] The present invention uses the first peak resonance amplitude as the main ice thickness detection parameter, and uses the first resonance frequency, the second resonance frequency and the second resonance amplitude as auxiliary parameters. The ice thickness detection result is calculated by these four parameters, which greatly improves the stability and accuracy of ice thickness detection.

[0090] The present invention constructs an ice thickness detection model and demonstrates the ice detection process in detail through experiments, so as to obtain the relationship between the first and second resonance peak parameters and the ice thickness detection. At the same time, the mathematical model is used to simply and quickly obtain ice information, thereby avoiding the problem of increased ice detection time caused by a complex ice thickness detection model. A temperature sensor is provided to measure the ambient temperature to control the sensor to work in an environment prone to ice formation, thereby avoiding energy loss in detection when there is no ice.

[0091] The detection surface, shielding metal plate and controller of the present invention can all be flattened, so that the thickness of the entire sensor can be controlled below the centimeter level, realizing patch-type detection; the capacitively coupled split ring microwave resonance ice detection sensor device also has the advantages of high cost performance, green, environmental protection, small size, and portability, and can be widely used in various detection fields.

[0092] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A microwave ice detection device based on capacitive coupling splitting ring, It is characterized in that include: A microwave signal controller (3), the microwave signal controller (3) being communicatively connected to the microwave resonance sensor (1); The microwave resonant sensor (1) comprises a substrate (101) arranged on the top surface of a shielding metal plate (2), and a copper foil (103) is etched on the top surface of the substrate (101); The copper foil (103) comprises two first split rings (1041) and a second split ring (1042) which are arranged opposite to each other, and the openings of the first split ring (1041) and the second split ring (1042) are arranged opposite to each other; a first microstrip line (1031) is arranged on the side of the first split ring (1041), and the first microstrip line (1031) extends to the edge of the substrate (101); a second microstrip line (1032) is arranged on the side of the second split ring (1042), and the second microstrip line (1032) extends to the edge of the substrate (101); When ice forms on the surface of the microwave resonant sensor (1), the microwave signal controller (3) emits a microwave signal with a changing frequency and transmits it to the copper foil (103), and the first splitting ring (1041) and the second splitting ring (1042) emit microwave signals to the mixture on the surface of the microwave resonant sensor (1), and the microwave signals are reflected, transmitted and absorbed by the mixture to form a measurement signal; After the measurement signal is transmitted to the microwave signal controller (3), the microwave signal controller (3) obtains the resonance amplitude and the resonance frequency in the measurement signal, and obtains ice thickness information based on the resonance amplitude and the resonance frequency.

2. A microwave ice detection device based on a capacitively coupled splitting ring according to claim 1, It is characterized in that A first signal interface (1021) is provided at the end of the first microstrip line (1031), and a second signal interface (1022) is provided at the end of the second microstrip line (1032); The first signal interface (1021) is connected to an input port (308) on the microwave signal controller (3), and the second signal interface (1022) is connected to an output port (305) on the microwave signal controller (3).

3. A microwave ice detection device based on a capacitively coupled splitting ring according to claim 1, It is characterized in that The microwave resonant sensor (1), the shielding metal plate (2) and the microwave signal controller (3) are sequentially assembled and arranged in an ice thickness detector housing (5), and the ice thickness detector housing (5) is installed on the surface of an ice-prone device.

4. A microwave ice detection device based on a capacitively coupled splitting ring according to claim 3, It is characterized in that The side wall of the ice thickness detector housing (5) is provided with a plurality of power line holes (9); A power line (7) is arranged in one of the power line holes (9), and the power line (7) is connected to the microwave signal controller (3); A signal transmission line (8) is arranged in another of the power line holes (9), and the signal transmission line (8) is connected to the microwave signal controller (3).

5. The microwave ice detection device based on a capacitively coupled splitting ring according to claim 1, It is characterized in that The microwave signal controller (3) embeds the device on a circuit board via a printed circuit board, and the formed circuit board can be installed in a protective shell or arranged separately outside the device.

6. A microwave ice detection system based on capacitive coupling splitting ring, It is characterized in that A microwave ice detection device based on a capacitively coupled splitting ring according to any one of claims 1 to 5, wherein the system further comprises: a temperature sensor (4), the temperature sensor (4) being embedded in the microwave signal controller (3), one end of the temperature sensor (4) being connected to a transformer (301) on the microwave signal controller (3), and the other end of the temperature sensor (4) being connected to a processor (302) on the microwave signal controller (3), the temperature sensor (4) being used to measure an external environment temperature; A wave source (303), the wave source (303) being embedded in the microwave signal controller (3) and connected to the transformer (301) and the processor (302) on the microwave signal controller (3), the wave source (303) being used to emit a microwave signal with a constant or variable power; a transmission signal receiver (309), the transmission signal receiver (309) being embedded in the microwave signal controller (3), one end of which is connected to the processor (302) on the microwave signal controller (3), and the other end of which is connected to the input port (308) on the microwave signal controller (3), the transmission signal receiver (309) being used to introduce a measurement signal on the microwave resonant sensor (1); A reflection signal receiver (304), the reflection signal receiver (304) being embedded in the microwave signal controller (3), one end of which is connected to the processor (302) on the microwave signal controller (3), and the other end of which is connected to the output port (305) on the microwave signal controller (3), the reflection signal receiver (304) being used to receive the microwave signal emitted by the wave source (303), and input the microwave signal into the microwave resonant sensor (1) through the output port (305).

7. A microwave ice detection system based on a capacitively coupled splitting ring according to claim 6, It is characterized in that After the transformer (301) converts the 220V alternating current into 12V direct current, the direct current drives the wave source (303) to emit a microwave signal with constant or variable power, which is transmitted to the output port (305) through the reflection signal receiver (304) and transmitted to the microwave resonance sensor (1) through the second signal interface (1022) to detect ice thickness information; The detection signal is transmitted to the input port (308) through the first signal interface (1021), and after being transmitted to the processor (302) through the transmission signal receiver (309), a comprehensive analysis is performed with the reflection signal and the wave source signal in the reflection signal receiver (304) to obtain microwave scattering parameters, and ice thickness information is obtained through the microwave scattering parameters.

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