CN111830093A - Real-time detection method and device for micro dielectric change of material based on radio frequency technology - Google Patents
Real-time detection method and device for micro dielectric change of material based on radio frequency technology Download PDFInfo
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- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/221—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance by investigating the dielectric properties
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
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Abstract
The invention discloses a real-time detection method and a device for micro dielectric change of a material based on a radio frequency technology. A large amount of electromagnetic fields are concentrated around the interdigital resonant unit, when a material to be measured is placed in the electromagnetic field concentrated region, the distribution of the electric fields around the resonant unit can be interfered, the resonant frequency and the attenuation amplitude of the material can be changed, and the change can obtain the tiny dielectric property change of the material through the scattering parameters of the measuring circuit. The invention can realize high-precision nondestructive detection of the change of the tiny components of the material, can also be popularized and applied to other fields, and has wide application range.
Description
Technical Field
The invention belongs to the technical field of design and application of microwave circuits, and particularly relates to a real-time detection method and device for micro dielectric change of a material based on a radio frequency technology.
Background
In the chemical field, the real-time regulation and control and detection of the component change of the reaction material play an important role in the performance index and the production efficiency of industrial products. For example, in the course of chemical reaction, the concentration and composition of the reaction solution change in real time as the chemical reaction progresses, and real-time regulation and detection are required. In addition, the real-time detection of the micro dielectric change of the material has wide application requirements in the fields of food, coal, building materials, knitwear and the like.
Common methods for detecting dielectric change of materials mainly comprise a near infrared analysis method, a meteorological chromatography method, a nuclear magnetic resonance method, a capacitance method, a microwave method and the like. The meteorological chromatography and nuclear magnetic resonance methods have high requirements on operators and detection material preparation, long detection pretreatment time and high detection cost. Although the near-infrared analysis method and the capacitance method have high detection speed, they are easily affected by external environments such as temperature and humidity, and the detection accuracy is low.
Microwave is electromagnetic wave with wavelength between infrared ray and radio wave, when microwave interacts with medium, polar molecules in medium such as water molecules will rotate along with alternating electromagnetic field, electric dipoles of water molecules will be disorderly arranged in no electric field, but under microwave field, water molecules will receive moment action in electric field, electric dipoles will be arranged towards electric field direction, when electric field direction changes, electric dipoles of water molecules will change accordingly. The macroscopic characterization of water by this microwave effect can be expressed in terms of dielectric constant. The dielectric constant, also known as permittivity, is an important parameter for characterizing the electrical properties of a dielectric. The dielectric constant of a material is related only to the dipole moment and polarizability of its constituent molecules. The dielectric loss of water is large, the energy attenuation caused by the water under the action of microwaves is far more remarkable than the loss caused by other media, and the water content in the substance directly influences the dielectric constant of the substance, so that the measurement of the dielectric constant of a measured object can directly reflect the essential properties of the substance. The measurement of the dielectric constant is an indirect measurement. It is contained in some functional relationship within the observable measurement parameter. The measuring method is generally based on transmission line theory, characteristic impedance and transmission constant, and forms corresponding functional relation with the actual measurable value. Therefore, only transmission line parameters (such as attenuation amplitude, phase, resonant frequency and other electrical parameters) of microwave signals passing through the medium are measured, the dielectric constant of the measured object can be calculated according to the functional relation, and finally, the change of the material components is reversely deduced.
The microwave detection methods commonly used at present mainly comprise four methods, namely a reflection method, a transmission method, a free space radiation method and a resonant cavity method. The reflection method usually adopts a coaxial line and a probe, and has the advantages of wider bandwidth and the defect that only reflection parameters are measured, and transmission parameters cannot be obtained, so the measurement precision is not high compared with other methods (a transmission method and a resonant cavity method), and the thickness of a measured material is required. The free space radiation method is mainly applied to the aspects of remote sensing, high temperature measurement and the like, and has the defects that the measured sample needs to be flat, more samples are needed at low frequency, and the measurement precision of a low-loss medium is limited. The resonant cavity method can only measure a single frequency point, has very small required volume for high-loss materials, is complex in analysis of measurement results, has high requirements on the shape of a solid material when the solid material is measured, and needs to be just placed into the resonant cavity, so the measurement of the solid material is usually damaged, the method has high requirements on the shape, the volume and the like of a detected material, and the preparation link is complex. The transmission method measurement system comprises a vector network analyzer and a transmission line capable of placing a measured medium, and the principle is that the dielectric constant of a measured object can be calculated according to a functional relation by measuring the measurement scattering parameters (such as attenuation amplitude, phase, resonant frequency and other electrical parameters) of the transmission line, and finally the change of the material components is reversely deduced.
The domestic and foreign microwave material detection device is mainly based on a reflection method and comprises devices such as a solid microwave source, a probe, a waveguide, an absorption load and the like, wherein the devices are mostly of a waveguide structure and have larger size; meanwhile, in order to improve the precision, the devices usually add a circulator, an isolator, a directional coupler and the like between the microwave source and the detection path to isolate and detect the signal source and the reflected echo. Therefore, the whole device has complex structure and higher manufacturing cost, is not easy to eliminate errors caused by noise interference, and limits the large-scale industrial application of the device. Recently, domestic researchers have conducted microwave humidity measurement device studies using a mixing technique with an active circuit configuration. Although the precision is partially improved, a microwave active circuit, a signal processing circuit and a specially designed horn transmitting and receiving antenna are further added on the basis of the integral reflection method measuring device, so that the circuit complexity of the measuring device is further increased, the device is complex to operate, the data processing is complex, and the anti-interference capability is weak, so that the measuring device cannot be applied in a large scale.
Disclosure of Invention
The invention provides a radio frequency circuit real-time online detection method and device based on a transmission line method, aiming at the defects of complex structure, complex data processing, weak anti-interference capability, high design cost and the like of the existing material detection device, and the radio frequency circuit real-time online detection method and device can realize high-precision nondestructive detection on small component changes of materials, and can be popularized and applied to reaction solution component detection in the chemical field, and real-time precise detection on moisture contents of plant seeds, food, beverages, tobacco, knitwear and the like in the agricultural field, and have wide application range.
Aiming at the problems, the invention provides a real-time online detection device for micro dielectric change of a material by using a microstrip line type radio frequency circuit based on a transmission line method, which consists of a microstrip type one-to-four power divider, a one-to-four combiner, an interdigital resonance unit and a vector network analyzer. A large number of electromagnetic fields are concentrated around the four conformal interdigital resonance units through an optimized design, when a dielectric material to be measured is placed in an electromagnetic field concentration area, the distribution of the electric fields around the resonance units is disturbed, circuit scattering parameters (such as attenuation amplitude, phase, resonant frequency and other electrical parameters) are changed, and tiny dielectric changes of the material can be visually detected through different measured scattering parameters. The invention has the advantages of simple structure, easy operation, high measurement precision, high detection speed, strong anti-interference capability, capability of realizing real-time online continuous detection, lower design and processing cost of the radio frequency circuit and wide application in the field of nondestructive detection of microwave materials.
In order to solve the technical problems, the invention adopts the following technical scheme:
one technical scheme of the invention is a real-time detection method for micro dielectric change of a material based on a radio frequency technology, which comprises the following steps:
s1: inputting a power signal;
s2: the power signal is divided into a plurality of paths of signals;
s3: a plurality of paths of signals enter a plurality of conformal interdigital resonance units simultaneously;
concentrating an electromagnetic field around the plurality of conformal interdigital resonant units,
s4: placing a material to be measured in the electromagnetic field concentration area to interfere the electric field distribution around the conformal interdigital resonance unit and change the resonance frequency and attenuation amplitude of an electric signal of the conformal interdigital resonance unit;
s5: the multi-path signals of the conformal interdigital resonance units simultaneously enter a one-to-many combiner to be mixed and then are output;
s6: detecting the resonance frequency and attenuation amplitude changes of the output signal and the input power signal of the step S1;
s7: analyzing the change detected in the step S6 to obtain the tiny dielectric change of the material.
As a preferred technical solution, the conformal interdigital resonance unit is formed by conforming the interdigital resonance unit to a cylinder in radius, so that the resonance unit in fig. 4 realizes a certain arc of bending, and horizontally placing a teflon test tube in a central area.
As an optimized technical scheme, the Teflon test tube is 75-85 mm long, 4-6 mm in inner diameter and 6-8 mm in outer diameter.
As a preferred technical scheme, the radius of the cylinder is 7-9 mm.
As a preferred technical solution, the power signal is divided into a plurality of paths of signals by a one-to-many power divider.
As a preferred technical solution, a power signal is input by a vector network analyzer in the step S1, and the vector network analyzer receives the output signal in the step S5 and performs the operations of the step S6 and the step S7.
The invention also provides a real-time detection device for the tiny dielectric change of a material based on a radio frequency technology, which comprises a one-to-two power divider, a one-to-four combiner, a conformal interdigital resonance unit and a vector network analyzer;
the output end of the vector network analyzer is connected with the input end of the one-to-two power divider, the vector network analyzer is used for outputting a power signal to enter the one-to-two power divider, and the one-to-two power divider is used for equally dividing the power signal into two paths of signals with equal amplitude and opposite phases;
the output end of one-to-two power divider is connected with the input ends of two one-to-two power dividers and is used for continuously dividing two paths of signals with equal amplitude and opposite phase into four paths of signals with equal amplitude and opposite phase;
the output ends of the two one-to-two power dividers are connected with the input end of the conformal interdigital resonance unit and are used for simultaneously inputting four paths of signals into the conformal interdigital resonance unit;
the output end of the conformal interdigital resonance unit is connected with the one-to-four combiner and is used for inputting four-path signals into the one-to-four combiner and combining the four-path signals into one-to-four combiner to be output;
the one-to-four combiner comprises three one-to-two combiners, wherein the output ends of two one-to-two combiners are respectively connected with the input end of one-to-two combiner; the output end of the one-in-four combiner is connected with the input end of the vector network analyzer, and the vector network analyzer is used for receiving the output signals of the one-in-four combiner and detecting the scattering parameters of the output signals to obtain the tiny dielectric change of the material.
As a preferred technical solution, the conformal interdigital resonance unit is formed by conforming the interdigital resonance unit to a cylinder in radius, so that the resonance unit in fig. 4 realizes a certain arc of bending, and horizontally placing a teflon test tube in a central area.
As an optimized technical scheme, the Teflon test tube is 75-85 mm long, 4-6 mm in inner diameter and 6-8 mm in outer diameter.
As a preferred technical scheme, the radius of the cylinder is 7-9 mm.
Has the advantages that:
the invention can realize high-precision real-time online nondestructive detection of micro component changes of liquid materials (chemical solution, industrial materials, milk yogurt and the like) and solid materials (cigarettes, concrete, plant seeds and the like).
The invention also has several advantages:
firstly, a microwave transmission line method is applied to the detection of the change of the tiny complex dielectric constant of the material, and the change of the components of the material to be detected is directly reflected by collecting the signal change of an input/output port (parameters such as the amplitude, the central frequency deviation and the like of S11 and S21), so that the design cost of the device is low, and the operation principle is clear and simplified;
secondly, the radio frequency circuit adopts a microstrip line structure, and the three equal power dividers and the three combiners are used for separating and synthesizing signals, so that the interference of external noise signals is inhibited, and the high-precision measurement capability is realized;
thirdly, the resonance unit of the radio frequency circuit adopts a conformal structure and is combined with a Teflon test tube, so that the solution to be measured can pass through the measurement area without damage, the measurement circuit is effectively protected, and corrosion is prevented;
and fourthly, the measurement object is flexibly adjusted, and the conformal structure design ensures that the measurement area not only can measure liquid materials, but also can conveniently measure solid materials. The test tube in the measuring area is easy to remove and can be replaced by solid materials such as cigarettes, concrete samples and the like.
Drawings
In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.
FIG. 1 is an overall framework diagram of the system of the present invention;
FIG. 2 is a diagram of a microwave detection device based on a radio frequency circuit according to the present invention;
FIG. 3 is a non-conformal interdigital resonant cell structure of the present invention wherein (a) front view, (b) side view;
FIG. 4 is a block diagram of a conformal interdigital resonant unit of the present invention;
FIG. 5 is a side view of the RF circuit configuration of the present invention;
FIG. 6 is a graph showing the change in S11 when the complex permittivity of the substance of the present invention is continuously changed, wherein (a) is a graph showing the change in the real part and (b) is a graph showing the change in the loss tangent (tan 6).
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all directional indicators (such as up, down, left, right, front, and back) in the embodiments of the present invention are only used to explain the relative position relationship between the components, the motion situation, and the like in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention will now be further described with reference to the accompanying drawings.
The embodiment of the invention mainly provides a real-time online detection method and a real-time online detection device for a radio frequency circuit based on a transmission line method, which can carry out high-precision nondestructive detection on the change of tiny components of materials (liquid, solid and other medium materials).
The method and the device are correspondingly integrated, and the method mainly comprises the following steps:
s1: inputting a power signal;
s2: the power signal is divided into a plurality of paths of signals;
s3: a plurality of paths of signals enter a plurality of conformal interdigital resonance units simultaneously;
concentrating an electromagnetic field around the plurality of conformal interdigital resonant units,
s4: placing a material to be measured in the electromagnetic field concentration area to interfere the electric field distribution around the conformal interdigital resonance unit and change the resonance frequency and attenuation amplitude of an electric signal of the conformal interdigital resonance unit;
s5: the multi-path signals of the conformal interdigital resonance units simultaneously enter a one-to-many combiner to be mixed and then are output;
s6: detecting the resonance frequency and attenuation amplitude changes of the output signal and the input power signal of the step S1;
s7: analyzing the change detected in the step S6 to obtain the tiny dielectric change of the material.
Referring to fig. 1, in fig. 1, the power divider 2, and the power divider 3 respectively refer to a one-to-two power divider, and the power divider 5, the power divider 6, and the power divider 7 refer to a one-to-two combiner. The detection device in the embodiment of the invention mainly comprises a one-to-four power divider, a one-to-four combiner, a conformal interdigital resonance unit and a vector network analyzer. Wherein, the one-to-four power divider is formed by combining three one-to-two power dividers; the one-to-four combiner is formed by combining three one-to-two combiners, signals are output by a vector network analyzer, the signals enter a one-to-two power divider and are equally divided into two paths of signals with equal amplitude and opposite phase, the two paths of signals simultaneously enter two one-to-two power dividers and are continuously divided into four paths of signals with equal amplitude and opposite phase, then the four paths of signals simultaneously enter four interdigital resonance units with conformal structures and interact with materials to be detected placed at the positions, then the four paths of signals continue to be transmitted forwards, the signals enter the combiner and are synthesized into one path of signal output, and scattering parameters of the output signals are detected by the vector network analyzer. A large number of electromagnetic fields are concentrated around the four interdigital resonance units through an optimized design, when a material to be measured is placed in the electromagnetic field concentrated region, the distribution of the electric fields around the resonance units can be interfered, the resonance frequency and the attenuation amplitude of the resonance units can be changed, and finally the change can be detected through the scattering parameters of two ports of a measuring circuit. FIG. 2 is a diagram of a detection apparatus of the RF circuit, wherein 1 and 2 are input/output ports of the circuit, respectively; the area 3 is a placement area of the material to be measured; regions 4 and 5 are one-to-four power dividers.
Conformal interdigital resonant cell design
The embodiment of the invention optimally designs the conformal interdigital resonance unit.
In order to expand an interaction area of an electromagnetic wave and a test material as much as possible and simultaneously realize the uniformity of the field intensity of an electric field in the test material, an interdigital resonance unit circuit with a conformal structure is designed. The resonant unit is shown in fig. 3 and 4, and the circuit is based on a microstrip line structure and can be conformed under a small radius. The amplitude and the resonant frequency of the S11 of the resonator are changed into-34.5 dB and 5.81GHz when the resonator is conformal within the range of R0.02 m, the corresponding amplitude and resonant frequency of the resonator are changed into-34.3 dB and 5.805GHz when the resonator is not conformal, and the change of the amplitude and the resonant frequency of the S11 before and after the resonator is conformal is very weak compared with that of the S11, and in addition, the relative change of the amplitude and the resonant frequency of the S11 is mainly measured by the method, and the difference can be ignored.
In the chemical field, many chemical solutions have certain toxicity and corrosiveness, in order to protect a circuit and realize continuous measurement in an industrial environment, the radius of an interdigital resonance unit is conformed to a cylinder with the radius of 8mm, so that the resonance unit in fig. 4 realizes bending with certain radian, a teflon test tube with the length of 80mm, the inner diameter of 5mm and the outer diameter of 7mm is horizontally placed in a region 3 in fig. 2, a solution to be measured can continuously pass through a measurement region through the teflon test tube, and the final test effect is shown in fig. 5.
Measurement of small change in dielectric constant of substance
Since the change of the material's macroscopic complex dielectric constant (═ j ″, where ' denotes the real part of the dielectric constant and ' denotes the imaginary part of the dielectric constant) will be caused by the small composition change, and the change of the complex dielectric constant can be visually characterized by the corresponding scattering parameters of the radio frequency circuit. The method and the device in the embodiment of the invention can realize high-precision nondestructive detection on the small component change of the material, can be popularized and applied to the component detection of reaction solution in the chemical field and the real-time precise detection of the moisture content of plant seeds, food, beverage, tobacco, knitwear and the like in the agricultural field, and have wide application range.
FIG. 6 shows the simulation result of S parameter when the real part and the imaginary part of the complex dielectric constant of the medium to be measured are respectively changed. As can be seen from fig. 6(a), the imaginary part of the dielectric constant of the material to be measured is kept constant at 0.05, while the real part of the complex dielectric constant of the material to be measured gradually shifts to the left when the interval from 1 to 10 is 1, and the amplitude of S11 is kept constant; when the real part of the complex dielectric constant of the measured material is kept constant and the loss tangent of the measured material is from 0.1 to 0.6, the amplitude of S11 becomes larger with the increase of the loss tangent without the shift of the resonance frequency and is fixed to 5.8GHz, as shown in FIG. 6 (b). Further, as can be seen from fig. 6(a), when the real part of the complex permittivity of the material to be measured is changed from the range of 1 to 10, the increase in the real part of the frequency-shifted complex permittivity of S11 is significantly changed. For example, when the real part of the complex permittivity increases from 2 to 3, the relative change of the frequency offset value corresponding to S11 is 1.35%. As can be seen from fig. 6(b), when the loss tangent of the material to be measured was changed from the range of 0.1 to 0.3, the magnitude of S11 was significantly changed with the increase of the loss tangent. For example, when the dielectric loss increases from 0.1 to 0.2, the corresponding S11 has a relative change in amplitude of 40.47%.
Example 1: design scheme for material detection
In the embodiment of the invention, the component changes of the ethanol-water mixed solution with different concentrations are accurately measured, and the volume fraction ratio of water in the ethanol directly influences the change of the complex dielectric constant of the whole mixture, thereby influencing the changes of the amplitude, the phase, the frequency offset and the like of S parameters of a circuit. The material to be measured was 5% aqueous ethanol solution at room temperature (25 deg.C)Degree), 69.03, tan 0.182, and when the volume fraction changes by 1%, 67.41 and 0.198 give the real permittivity at 5.8GHz under normal pressure, the relative change is Δ1.62 and Δ tan8 is 0.016, the corresponding S11 frequency offset can be calculated by simulation similar to fig. 6 and is 1.38%; similarly, the amplitude variation is 31.2%. Therefore, if the volume fraction of ethanol water changes by 1%, the corresponding S11 amplitude attenuation and frequency offset change significantly, and the reverse can be directly obtained by measuring the S11 parameter.
Example 2: specific structure of radio frequency circuit
The detection device mainly comprises a one-to-four power divider, a one-to-four combiner, a conformal interdigital resonance unit and a vector network analyzer. The signal is output by a vector network analyzer, enters a one-to-two power divider and then is equally divided into two paths of signals with equal amplitude and opposite phase, the two paths of signals simultaneously enter two one-to-two power dividers and are continuously divided into four paths of signals with equal amplitude and opposite phase, then the four paths of signals simultaneously enter four interdigital resonance units with conformal structures and interact with a material to be detected placed at the position, then the four paths of signals continue to propagate forwards, enter a combiner and then are synthesized into one path of signal output, and the scattering parameter of the output signal is detected by the vector network analyzer. A large number of electromagnetic fields are concentrated around the four interdigital resonance units through an optimized design, when a material to be measured is placed in the electromagnetic field concentrated region, the distribution of the electric fields around the resonance units can be interfered, the resonance frequency and the attenuation amplitude of the resonance units can be changed, and finally the change can be detected through the scattering parameters of two ports of a measuring circuit.
Example 3: conformal interdigital resonance unit structure
In order to enlarge the interaction area of the electromagnetic wave and the test material as much as possible and simultaneously realize the uniformity of the field intensity of the electric field in the test material, the invention designs the interdigital resonance unit circuit with the conformal structure. The number of the interdigital is 3 pairs, the length is 6.2mm, the width is 1mm, the gap is 0.4mm, and the gap is 0.8 mm. The circuit is based on a microstrip line structure and can be conformal under a small radius. The amplitude and the resonant frequency of the S11 of the resonator are changed into-34.5 dB and 5.81GHz when the resonator is conformal within the range of R0.02 m, the corresponding amplitude and resonant frequency of the resonator are changed into-34.3 dB and 5.805GHz when the resonator is not conformal, and the change of the amplitude and the resonant frequency of the S11 before and after the resonator is conformal is very weak compared with that of the S11, and in addition, the relative change of the amplitude and the resonant frequency of the S11 is mainly measured by the method, and the difference can be ignored. In order to protect the circuit and realize continuous measurement in an industrial environment, the radius of the interdigital resonance unit is conformal to a cylinder with the radius of 8mm, so that the resonance unit is bent at a certain radian, a Teflon test tube with the length of 80mm, the inner diameter of 5mm and the outer diameter of 7mm is horizontally placed in a measurement area, and a solution to be measured can continuously pass through the measurement area through the Teflon test tube.
In summary, the present invention provides a real-time detection apparatus for micro dielectric variation of materials based on radio frequency technology. The device can realize high-precision real-time online nondestructive detection on the micro component change of liquid materials (chemical solution, industrial materials, milk yogurt and the like) and solid materials (cigarettes, concrete, plant seeds and the like).
The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.
Claims (10)
1. A real-time detection method for micro dielectric change of a material based on a radio frequency technology is characterized by comprising the following steps:
s1: inputting a power signal;
s2: the power signal is divided into a plurality of paths of signals;
s3: a plurality of paths of signals enter a plurality of conformal interdigital resonance units simultaneously;
concentrating an electromagnetic field around the plurality of conformal interdigital resonant units,
s4: placing a material to be measured in the electromagnetic field concentration area to interfere the electric field distribution around the conformal interdigital resonance unit and change the resonance frequency and attenuation amplitude of an electric signal of the conformal interdigital resonance unit;
s5: the multi-path signals of the conformal interdigital resonance units simultaneously enter a one-to-many combiner to be mixed and then are output;
s6: detecting the resonance frequency and attenuation amplitude changes of the output signal and the input power signal of the step S1;
s7: analyzing the change detected in the step S6 to obtain the tiny dielectric change of the material.
2. The real-time detection method for the small dielectric variation of the material based on the radio frequency technology as claimed in claim 1, wherein the conformal interdigital resonance unit is formed by placing a teflon test tube horizontally in a central area by conforming the interdigital resonance unit to a cylinder in a radius such that the resonance unit in fig. 4 realizes a certain arc of curvature.
3. The real-time detection method for the small dielectric variation of the material based on the radio frequency technology as claimed in claim 2, wherein the Teflon test tube has a length of 75-85 mm, an inner diameter of 4-6 mm and an outer diameter of 6-8 mm.
4. The real-time detection method for the small dielectric variation of the material based on the radio frequency technology as claimed in claim 2, wherein the radius of the cylinder is 7-9 mm.
5. The method of claim 1, wherein the power signal is divided into a plurality of signals by a power divider with a plurality of power dividers.
6. The real-time detection method for the tiny dielectric variation of the material based on the radio frequency technology as claimed in claim 1, wherein: a power signal is input by the vector network analyzer in the step S1, the vector network analyzer receives the output signal in the step S5 and performs the operations of the step S6 and the step S7.
7. A real-time detection device for micro dielectric change of a material based on a radio frequency technology is characterized in that: the device comprises a one-to-two power divider, a one-to-four combiner, a conformal interdigital resonance unit and a vector network analyzer;
the output end of the vector network analyzer is connected with the input end of the one-to-two power divider, the vector network analyzer is used for outputting a power signal to enter the one-to-two power divider, and the one-to-two power divider is used for equally dividing the power signal into two paths of signals with equal amplitude and opposite phases;
the output end of one-to-two power divider is connected with the input ends of two one-to-two power dividers and is used for continuously dividing two paths of signals with equal amplitude and opposite phase into four paths of signals with equal amplitude and opposite phase;
the output ends of the two one-to-two power dividers are connected with the input end of the conformal interdigital resonance unit and are used for simultaneously inputting four paths of signals into the conformal interdigital resonance unit;
the output end of the conformal interdigital resonance unit is connected with the one-to-four combiner and is used for inputting four-path signals into the one-to-four combiner and combining the four-path signals into one-to-four combiner to be output;
whether or not to add: the one-to-four power divider comprises three one-to-two power dividers, wherein the output end of one-to-two power divider is respectively connected with the input ends of two one-to-two power dividers; the one-to-four combiner comprises three one-to-two combiners, wherein the output ends of two one-to-two combiners are respectively connected with the input end of one-to-two combiner;
the output end of the one-in-four combiner is connected with the input end of the vector network analyzer, and the vector network analyzer is used for receiving the output signals of the one-in-four combiner and detecting the scattering parameters of the output signals to obtain the tiny dielectric change of the material.
8. The device for real-time detection of small dielectric change of material based on radio frequency technology as claimed in claim 7, wherein: the conformal interdigital resonance unit enables the resonance unit in fig. 4 to realize bending with a certain radian by enabling the interdigital resonance unit to be in a conformal shape on a cylinder, and the Teflon test tube is horizontally placed in a central area to be formed.
9. The device for real-time detection of small dielectric change of material based on radio frequency technology as claimed in claim 8, wherein: the Teflon test tube is 75-85 mm long, 4-6 mm in inner diameter and 6-8 mm in outer diameter.
10. The device for real-time detection of small dielectric change of material based on radio frequency technology as claimed in claim 8, wherein: the radius of the cylinder is 7-9 mm.
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