CN116773618A - Anti-interference label test system for passive detection of soil humidity - Google Patents
Anti-interference label test system for passive detection of soil humidity Download PDFInfo
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Abstract
The application discloses an anti-interference label test system for passive detection of soil humidity, which comprises: the system comprises a network analyzer U1, an electromagnetic shielding box U2, a CRFID sensor tag U3, a turntable U4, a quadrangular horn antenna U5 and a shielding wire U6; the network analyzer U1 is connected with the quadrangular horn antenna U5 in the electromagnetic shielding box U2 through the shielding wire U6; one side of the electromagnetic shielding box U2 is connected with the rotary disc U4, and the CRFID sensor tag U3 is designed on the rotary disc U4. By utilizing the embodiment of the application, the accuracy of the calibration of the soil humidity detection model can be improved, and a reliable theory and calibration scheme is provided for passive anti-interference detection of the soil humidity.
Description
Technical Field
The application belongs to the technical field of soil humidity detection, and particularly relates to an anti-interference label test system for passive detection of soil humidity.
Background
Accurate agricultural soil health monitoring requires large-scale deployment of sensors that can be used to monitor soil parameters such as humidity, temperature, microbial activity, and nitrogen concentration, and report soil conditions to farmers. Among the various parameters, moisture is an important parameter in agriculture, and is usually quantified by the volumetric moisture content of the soil, which has a great impact on plant growth, nutrient transport, and soil properties. Variations in soil volume moisture content (VWC) also directly affect the biomass and enzymatic activity of microorganisms of different soil types.
Existing soil unit moisture content quantification methods include conventional gravity measurement, wired and remote sensing methods. The disadvantages of the gravimetric method are laborious physical work, compaction of the soil during transport, and errors due to moisture loss by evaporation. The sensing method of calculating VWC by measuring the permittivity of the soil can avoid the physical effort of moving the soil sample from the site to the laboratory although various sensors and probes have been developed for site measurement and quantification of VWC, they are subject to conditions as they require a wired connection to an external data logger or possibly a wireless data transmission node. Furthermore, these wired systems are slow to deploy, with the risk of damage to agricultural machinery in conventional agricultural activities.
To address this limitation, different large-scale imaging systems, namely hyperspectral images and high resolution satellite images, are also used for precision agricultural applications. In-situ measurements using imaging systems are done by unmanned aerial vehicles equipped with multispectral cameras, thermal cameras, RGB cameras or light detection and ranging systems. While these image-based techniques work best in terms of non-destructive analysis of spatial variability in crop pressure, disease and yield, the major disadvantage of these methods is the inability to extract subsoil condition information early.
Disclosure of Invention
The application aims to provide an anti-interference label test system for passive detection of soil humidity, which aims to solve the defects in the prior art, improve the accuracy of calibration of a soil humidity detection model and provide a reliable theory and calibration scheme for passive anti-interference detection of soil humidity.
One embodiment of the present application provides an anti-tamper tag testing system for passive detection of soil moisture, the system comprising: the system comprises a network analyzer U1, an electromagnetic shielding box U2, a CRFID sensor tag U3, a turntable U4, a quadrangular horn antenna U5 and a shielding wire U6; wherein,,
the network analyzer U1 is connected with the quadrangular horn antenna U5 in the electromagnetic shielding box U2 through the shielding wire U6;
one side of the electromagnetic shielding box U2 is connected with the rotary disc U4, and the CRFID sensor tag U3 is designed on the rotary disc U4.
Optionally, the CRFID sensor tag U3 includes: dielectric substrate, ground layer, first resonator, second resonator, encapsulation layer.
Optionally, the dielectric substrate is made of an acrylic substrate material, the grounding layer is made of pure copper material and ethyl acetate in a mixing mode, the first resonator and the second resonator are made of pure copper material and ethyl acetate in a mixing mode, and the packaging layer is made of PDMS solution and curing agent in a mixing mode.
Optionally, the ground layer is assembled at the bottom of the dielectric substrate and serves as a sensor ground plane; the first resonator and the second resonator are assembled on the surface of the dielectric substrate, the assembly angle is 45 degrees, and the first resonator and the second resonator are used as resonator units of the sensor tag; the packaging layer comprises a packaging layer surface layer and a packaging layer bottom layer.
Optionally, the electromagnetic wave emitted by the first port of the network analyzer U1 is transmitted to the vertical ridge of the quadrangular horn antenna U5 in the electromagnetic shielding box U2 through the shielding line U6 to generate a vertical polarization interrogation signal, the electromagnetic wave of the horizontal polarization after being reflected by the CRFID sensor tag U3 is acquired by the horizontal ridge of the quadrangular horn antenna U5, and is transmitted to the second port of the network analyzer U1 through the shielding line U6, the network analyzer U1 receives the frequency signal of the electromagnetic wave, the angle of the CRFID sensor tag U3 in the electromagnetic shielding box U2 is rotatable through the turntable U4, the backward scattering signal data under different angles is obtained through testing, and the original electromagnetic signal level sample data set is obtained through the transformation processing of the bottom polar coordinate system data.
Optionally, the CRFID sensor tag U3 is configured to sense an electrical characteristic signal when the effective dielectric constant of the soil changes, process the electrical characteristic signal of the CRFID sensor tag U3, and derive a formula by using the processed information to obtain the soil humidity identification model.
Optionally, the electrical characteristic signal includes: backscatter signal data, power, dielectric constant, resonant frequency, return loss.
Optionally, the quadrangular horn antenna U5 is formed by intersecting a vertical ridge antenna and a horizontal ridge antenna horizontally by 90 degrees, and is used as a cross polarization antenna; the CRFID sensor tag U3 is set to 45 ° by the access angle of the transmitting antenna as a polarization-changing tag.
Optionally, the CRFID sensor tag U3 is composed of a shorted dipole structure, and a resonant structure of the shorted dipole structure is used to backscatter an incident signal, while embedding electromagnetic features in the form of resonance in a reflected signal.
Optionally, the vertical ridge antenna is configured to act as a transmitter to generate a vertically polarized interrogation signal and the horizontal ridge antenna is configured to act as a receiver to read a horizontally polarized signal backscattered from the sensor tag.
Compared with the prior art, the anti-interference label test system for passive detection of soil humidity provided by the application comprises the following components: the system comprises a network analyzer U1, an electromagnetic shielding box U2, a CRFID sensor tag U3, a turntable U4, a quadrangular horn antenna U5 and a shielding wire U6; the network analyzer U1 is connected with the quadrangular horn antenna U5 in the electromagnetic shielding box U2 through the shielding wire U6; one side of the electromagnetic shielding box U2 is connected with the rotary disc U4, the CRFID sensor tag U3 is designed on the rotary disc U4, so that the accuracy of calibrating a soil humidity detection model is improved, and a reliable theory and calibration scheme are provided for passive anti-interference detection of soil humidity.
Drawings
Fig. 1 is a schematic structural diagram of an anti-interference tag test system for passive detection of soil humidity according to an embodiment of the present application;
FIG. 2 is a schematic flow chart of designing and manufacturing a CRFID sensor tag according to an embodiment of the present application;
fig. 3 is a test chart of a CRFID sensor tag according to an embodiment of the present application.
Detailed Description
The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the application.
Because subsoil telemetry requires a high-efficiency, low-cost and high-resolution measuring system to meet the all-weather monitoring requirement of space-variant subsoil, the advantages of the passive wireless chipless sensing technology make the subsoil application ideal, and the application provides a novel application and detection method of the battery-free chipless sensor label, which can meet the urgent requirement of the agricultural field on wide-area monitoring of soil VWC by providing a low-cost detection method.
One embodiment of the present application provides an anti-tamper tag testing system for passive detection of soil moisture, see fig. 1, which may include: the network analyzer U1, the electromagnetic shielding box U2, the CRFID sensor tag U3, the turntable U4, the quadrangular horn antenna U5 and the shielding wire U6 are used for realizing the change of CRFID back scattering signals caused by the change of effective dielectric constants due to the change of soil humidity in a research soil environment.
The network analyzer U1 is connected with the quadrangular horn antenna U5 in the electromagnetic shielding box U2 through the shielding wire U6; one side of the electromagnetic shielding box U2 is connected with the rotary disc U4, and the CRFID sensor tag U3 is designed on the rotary disc U4.
Specifically, the CRFID sensor tag U3 includes: a dielectric substrate, a grounding layer, a first resonator (resonator 1), a second resonator (resonator 2) and an encapsulation layer. The dielectric substrate is made of an acrylic substrate material, the grounding layer is made of pure copper material and ethyl acetate in a mixing mode, the first resonator and the second resonator are made of pure copper material and ethyl acetate in a mixing mode, and the packaging layer is made of PDMS solution and curing agent in a mixing mode.
Specifically, the grounding layer is assembled at the bottom of the dielectric substrate and is used as a sensor grounding plane; the first resonator and the second resonator are assembled on the surface of the dielectric substrate, the assembly angle is 45 degrees, and the first resonator and the second resonator are used as resonator units of the sensor tag; the packaging layer comprises a packaging layer surface layer and a packaging layer bottom layer.
Illustratively, as shown in FIG. 2, the CRFID sensor tag U3 may be fabricated as follows: the method comprises the steps of laser cutting a dielectric substrate U31, assembling a dielectric substrate bottom U32 on a grounding layer, assembling a dielectric substrate surface U33 on a resonator, packaging a sensor tag U34 and manufacturing a finished sensor tag U35.
The laser cutting medium substrate U31 includes an acrylic substrate U311: the preparation method comprises the following steps of using CO 2 The laser engraving system cuts the media into 100mm x 100mm specifications.
In this embodiment, the dielectric substrate is made of an acrylic substrate material, and the dielectric substrate may be a square plate with a thickness of 100mm×100mm, and a thickness of 2.70cm.
The bottom U32 of the grounding layer assembly dielectric substrate comprises an acrylic-based plate U321 and a copper strip grounding layer U322: the preparation method comprises the following steps of using CO 2 The laser engraving system cuts the copper foil tape into a specification of 100mm x 100mm and assembles it to the bottom of the dielectric substrate as a sensor ground plane.
In this embodiment, the copper strip grounding layer is prepared by mixing pure copper material with ethyl acetate. The copper strip grounding layer is a square sheet with the thickness of 100mm multiplied by 100mm, the thickness of the copper base material is 0.018mm, the thickness of the back adhesive is 0.032mm, and the total thickness is 0.05mm.
The surface U33 of the resonator assembling medium substrate comprises an acrylic base plate U331, a copper strip grounding layer U332, a resonator 1U333 and a resonator 2U334.
The preparation method comprises the following steps of using CO 2 The laser engraving system cuts the copper foil tape into specifications of 9cm×1cm and 10cm×1cm, and assembles the copper foil tape to the surface of the dielectric substrate at an assembly angle of 45 ° as a resonator unit of the sensor tag.
In this embodiment, the resonator is made of pure copper material and ethyl acetate. The U333 resonator 1 was a rectangular piece of 10cm×1cm, and the U334 resonator 2 was a rectangular piece of 10cm×1 cm.
The surface U34 of the resonator assembling medium substrate comprises an acrylic-based board U341, a copper strip grounding layer U342, a resonator 1U343, a resonator 2U344, a packaging layer bottom layer U345 and a packaging layer surface layer U346.
The manufacturing method comprises the steps of packaging a sensor label by using a PDMS solution, firstly calculating the dosage of the PDMS solution at the bottom layer of a packaging layer, mixing the PDMS solution according to a proportion, pouring the mixture into a mould after magnetic stirring is finished, placing the mould into a vacuum pump for degassing for 30 minutes, taking out the mould after surface bubbles are eliminated, placing the mould into an electric heating constant temperature drying oven, drying at 70 ℃ for 2 hours, taking out the mould, and placing the prepared sensor label on the bottom layer of the cured packaging layer; calculating the dosage of the PDMS solution on the surface layer of the packaging layer, mixing the PDMS solution according to a proportion, pouring the mixture into a mold after magnetic stirring is completed, placing the mold into a vacuum pump for degassing for 30 minutes, taking out the mold after surface bubbles are eliminated, placing the mold into an electric heating constant temperature drying oven, drying at 70 ℃ for 4 hours, taking out the mold after the mold is cooled for 1 hour, and demolding the mold.
In this embodiment, the surface layer of the encapsulation layer and the bottom layer of the encapsulation layer are prepared by mixing PDMS solution and a curing agent, and the mixing ratio is 10:1, the U44 packaging layer bottom layer is a square layer with the thickness of 10.5cm multiplied by 0.2cm, and the U45 packaging layer surface layer is a square layer with the thickness of 10.5cm multiplied by 0.2 cm.
The finished sensor tag U35: the manufacturing step is to use a scalpel to carry out surface finishing on the sensor label after demolding and packaging. In this example, the final sensor label was a square sheet of 10.5cm×10.5cm in size and 3.15cm in thickness.
Specifically, the anti-interference label test system test flow is as follows: electromagnetic waves emitted by a first port of the network analyzer U1 are transmitted to a vertical ridge of a quadrangular horn antenna U5 in the electromagnetic shielding box U2 through the shielding wire U6 to generate vertical polarization interrogation signals, the horizontal polarized electromagnetic waves reflected by the CRFID sensor tag U3 are acquired by the horizontal ridge of the quadrangular horn antenna U5 and are transmitted to a second port of the network analyzer U1 through the shielding wire U6, the network analyzer U1 receives frequency signals of the electromagnetic waves, angles of the CRFID sensor tag U3 in the electromagnetic shielding box U2 can be rotated through the turntable U4, backward scattering signal data under different angles are obtained through testing, and an original electromagnetic signal level sample data set is obtained through conversion processing of bottom polar coordinate system data.
Specifically, the quadrangular horn antenna U5 is formed by intersecting a vertical ridge antenna and a horizontal ridge antenna by 90 degrees horizontally and is used as a cross polarization antenna; the access angle of the CRFID sensor tag U3 by the transmitting antenna is set to be 45 degrees, and the CRFID sensor tag is used as a variable polarization tag so as to realize system anti-interference.
Illustratively, an anti-interference principle of a passive detection test system is: considering environmental interference factors, such as the fact that the transmit and receive antennas are in the same polarization, which can result in a large amount of clutter in the backscattered signal received from the CRFID sensor tag, cross-polarized antennas are designed to be used, by using transmit and receive antennas operating in cross-polarization (transmit antenna transmitting signals in vertical polarization and receive antenna receiving signals in horizontal polarization) to avoid these unwanted reflections from the surrounding environment, chipless CRFID sensor tags are set to have an access angle of 45 ° by the transmit antenna to act as a variable polarization tag, by using variable polarization CRFID sensor tags, it is possible to backscatter the vertically polarized signal from the transmitter in both vertical and horizontal polarizations, since the non-variable polarization background signal from the environment will typically reflect in the same vertical polarization, and the horizontally polarized reflected signal will contain less noise. Therefore, the horizontal polarization receiver can collect horizontal polarization signals from the CRFID sensor tag with less interference background noise, and meanwhile, the test environment is built in the electromagnetic shielding box, so that the environment interference is reduced sufficiently, and the data accuracy is ensured.
Specifically, the CRFID sensor tag U3 is composed of a shorted dipole structure, and a resonant structure of the shorted dipole structure is used for back scattering an incident signal, and meanwhile, electromagnetic features in a resonant form are embedded in a reflected signal, so that tag anti-interference is realized.
An exemplary design principle of the anti-interference tag is as follows: the chipless CRFID sensor tag consists of a shorted dipole structure that is capable of back scattering an incident signal while embedding electromagnetic features in the form of resonances in the reflected signal. When the chipless sensor is interrogated 45 ° relative to the reader antenna, the CRFID sensor tag can then act as a variably polarized CRFID sensor tag, when the chipless sensor is interrogated at other angles by the reader antenna, the CRFID sensor tag is at its resonant frequency with a maximum amplitude back-scattered signal, a dual resonator is designed as an electromagnetic code of the tag, displayed and distinguished spectrally, as a result of having embedded resonant form of electromagnetic features in the reflected signal, a 2MM thick PDMS layer is designed to encapsulate it, enabling the sensor to operate stably in the soil, as the metallic microstrip antenna and metallic ground layers are susceptible to oxidation and corrosion.
In particular, the vertical ridge antenna is used as a transmitter to generate a vertically polarized interrogation signal and the horizontal ridge antenna is used as a receiver to read a horizontally polarized signal backscattered from the sensor tag.
The quadrangular horn antenna U5 is formed by intersecting a vertical ridge antenna and a horizontal ridge antenna horizontally at 90 degrees. The vertical ridge antenna acts as a transmitter to generate a vertically polarized interrogation signal and the horizontal ridge antenna acts as a receiver to read the horizontally polarized signal backscattered from the sensor tag (the former for transmitting an interrogation and the latter for receiving a reply), interfering reflections from the surrounding environment being avoided by using transmitters and receivers operating in cross polarization.
Specifically, the CRFID sensor tag U3 is configured to sense an electrical characteristic signal when the effective dielectric constant of soil changes, process the electrical characteristic signal of the CRFID sensor tag U3, and derive a formula by using the processed information to obtain a soil humidity identification model. Wherein the electrical signature signal comprises: backscatter signal data, power, dielectric constant, resonant frequency, return loss.
In practical application, the anti-interference tag test system for passively detecting the soil humidity is placed in an environment containing various medium interference, and three groups of experiments are designed for the CRFID sensor tag.
The first experiment aims at testing the working condition of the CRFID sensor label in the air, the second experiment aims at testing the working condition of the CRFID sensor label which is passivated by a PDMS layer with the thickness of millimeter and placed in the air, testing the resonance frequency of the label passivated by the PDMS layer, comparing with the test data of the label in the first experiment, and researching the percentage deviation of the resonance frequency; the third experiment aims at testing the working condition of the sensor label which is passivated by the PDMS layer with the thickness of millimeter and then placed in soil, testing the resonance frequency of the label passivated by the PDMS layer under different soil humidity and depth, comparing the resonance frequency with the label test data of the experiment one and the experiment two, researching the percentage deviation of the resonance frequency in dry soil and researching the percentage deviation of the resonance frequency of the CRFID sensor label under different soil humidity at the same soil depth.
Fig. 3 is a test chart of a CRFID sensor tag according to an embodiment of the present application, as shown in fig. 3, the CRFID sensor tag used in the first experiment is a U41 copper-clad substrate dual-resonance sensor, the CRFID sensor tag U42 copper-clad substrate dual-resonance sensor package used in the second experiment is a U43 copper-clad substrate dual-resonator sensor package used in the third experiment is a soil layer.
As shown in fig. 3, the CRFID sensor tag includes: u41 copper-clad substrate double-resonance sensor, U42 copper-clad substrate double-resonance sensor package, U43 copper-clad substrate double-resonance sensor package placement soil layer.
The U41 copper-clad substrate double-resonance sensor comprises an acrylic-based plate U411, a copper strip resonator 1U412, a copper strip resonator 2U413, a packaging layer bottom layer U414 and a packaging layer surface layer U415.
The U42 copper-clad substrate double-resonance sensor package comprises an acrylic substrate U2391, a copper strip resonator 1U422, a copper strip resonator 2U423, a packaging layer bottom layer U424 and a packaging layer surface layer U2425.
The packaging and placing soil layer of the U43 copper-clad substrate double-resonance sensor comprises an acrylic substrate U431, a copper strip grounding layer U432, a copper strip resonator 1U433, a copper strip resonator 2U434, a packaging layer bottom layer U435, a packaging layer surface layer U436, a soil layer bottom layer U437 and a soil layer surface layer U438.
In practical application, the electrical characteristic signals of the CRFID sensing terminal (CRFID sensor tag) are utilized to sense the electrical characteristic signals when the effective dielectric constant of the soil changes, the electrical characteristic signals of the CRFID sensing terminal are processed, and formula deduction is carried out by utilizing the processed information to obtain the soil humidity identification model.
The purpose of this step is to use the CRFID sensing terminal to sense the electrical characteristic signal when the effective dielectric constant around the sensor changes in three sets of control experiments, the electrical characteristic signal includes: backscattering signal data, power, dielectric constant, resonant frequency, return loss; and processing the electrical characteristic signals output by the CRFID sensing terminal by using a data reading processing terminal, so that the electrical characteristic signals can be used for formula calculation and deduction, and carrying out formula deduction on the processed information to finally obtain the soil humidity identification model.
The first group of experimental data is the working condition of the CRFID sensor label in the air, firstly, idle sensor data, namely electric characteristic data which is not passivated by the PDMS layer, is used as reference data for calibrating the sensor, and the test can be carried out for a plurality of times every half hour, so that the behavior of the sensor is recorded;
the data of the second group of experiments are working conditions of the CRFID sensor label in air after being passivated by a PDMS layer with the thickness of 2mm, as the dielectric constant of the passivation layer is increased, the resonance frequencies of the resonator 1 and the resonator 2 deviate to different degrees, the deviation degree of the resonance frequencies is recorded and is compared with the sensor data of the first group, and the data of the sensor at the moment, namely, an electric characteristic signal when the soil humidity is not recognized is used as reference data of a calibration sensor;
the third set of experimental data is the operation of CRFID sensor tags in dry soil and soil of different humidity where the sensor tags are passivated by a PDMS layer of thickness 2mm, the CRFID sensor tags being buried in soil whose dielectric constant varies according to the volumetric moisture content (VWC) of the soil, the resonant frequency of the CRFID sensor tags decreasing as the effective dielectric constant of the soil increases with increasing volumetric moisture content of the soil. Based on the characteristics, the water content of different soil volumes is taken as a calibration value, the resonance frequency is changed as a monitoring value, the dielectric constant is taken as a detection variable, and the function model is fitted by utilizing the parameter data, so that the soil humidity model is identified by different resonance frequency change amounts.
The resonant frequency of a chipless sensor tag depends primarily on two parameters: the geometry of the metal pattern forming the resonator and the effective dielectric constant of the medium in the vicinity of the resonator. For a sensor tag constructed with microstrip lines, the resonant frequency can be given by the formula:
wherein fr represents the resonant frequency; c represents the speed of light; lr denotes the length of the shorted dipole of the resonator; epsilon eff Indicating the effective dielectric constant around the dipole antenna. By using this equation, the desired design parameters of the sensor tag and its operating resonant frequency can be calculated.
VWC and ε of soil eff The correlation equation between can be written as:
where VWC represents the volumetric water content of the soil, by using this equation, a soil moisture recognition model can be obtained.
In summary, the application designs three groups of control experiments to test by taking the effective dielectric constant of the resonant frequency of the short-circuit dipole resonator CRFID sensor tag along with the volume water content of the soil and taking noise such as environmental interference and the like as an entry point in a cross-polarized working environment of the variable polarization CRFID sensor tag, designing and manufacturing the soil humidity tag and building an anti-interference tag test system for passive detection of the soil humidity, and the resonant frequency of the CRFID sensor tag is reduced because the effective dielectric constant of the soil is increased along with the volume water content of the soil. Based on the characteristics, the water content of different soil volumes is taken as a calibration value, the resonance frequency change is taken as a monitoring value, the dielectric constant is taken as a detection variable, and the function model is fitted by utilizing the parameter data, so that the soil humidity model is identified by different resonance frequency change amounts, and a reliable theory and calibration method is provided for passive anti-interference detection of the soil humidity.
Therefore, the anti-interference label test system for passive detection of soil humidity provided by the application comprises the following components: the system comprises a network analyzer U1, an electromagnetic shielding box U2, a CRFID sensor tag U3, a turntable U4, a quadrangular horn antenna U5 and a shielding wire U6; the network analyzer U1 is connected with the quadrangular horn antenna U5 in the electromagnetic shielding box U2 through the shielding wire U6; one side of the electromagnetic shielding box U2 is connected with the rotary disc U4, the CRFID sensor tag U3 is designed on the rotary disc U4, so that the accuracy of calibrating a soil humidity detection model is improved, and a reliable theory and calibration scheme are provided for passive anti-interference detection of soil humidity.
While the foregoing is directed to embodiments of the present application, other and further embodiments of the application may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims (10)
1. An anti-tamper tag testing system for passive detection of soil moisture, the system comprising: the system comprises a network analyzer U1, an electromagnetic shielding box U2, a CRFID sensor tag U3, a turntable U4, a quadrangular horn antenna U5 and a shielding wire U6; wherein,,
the network analyzer U1 is connected with the quadrangular horn antenna U5 in the electromagnetic shielding box U2 through the shielding wire U6;
one side of the electromagnetic shielding box U2 is connected with the rotary disc U4, and the CRFID sensor tag U3 is designed on the rotary disc U4.
2. The system of claim 1, wherein the CRFID sensor tag U3 comprises: dielectric substrate, ground layer, first resonator, second resonator, encapsulation layer.
3. The system of claim 2, wherein the dielectric substrate is an acrylic substrate material, the ground layer is made of pure copper material mixed with ethyl acetate, the first resonator and the second resonator are made of pure copper material mixed with ethyl acetate, and the encapsulation layer is made of PDMS solution mixed with a curing agent.
4. A system according to claim 3, wherein the ground layer is mounted on the bottom of the dielectric substrate as a sensor ground plane; the first resonator and the second resonator are assembled on the surface of the dielectric substrate, the assembly angle is 45 degrees, and the first resonator and the second resonator are used as resonator units of the sensor tag; the packaging layer comprises a packaging layer surface layer and a packaging layer bottom layer.
5. The system of claim 4, wherein the quadrangular horn antenna U5 is composed of a vertical ridge antenna horizontally crossing a horizontal ridge antenna by 90 ° as a cross polarized antenna; the CRFID sensor tag U3 is set to 45 ° by the access angle of the transmitting antenna as a polarization-changing tag.
6. The system of claim 5, wherein the electromagnetic waves emitted from the first port of the network analyzer U1 are transmitted to the vertical ridge of the quadrangular horn antenna U5 in the electromagnetic shielding box U2 through the shielding line U6 to generate a vertical polarization interrogation signal, the electromagnetic waves of the horizontal polarization reflected by the CRFID sensor tag U3 are acquired by the horizontal ridge of the quadrangular horn antenna U5 and transmitted to the second port of the network analyzer U1 through the shielding line U6, the network analyzer U1 receives the frequency signals of the electromagnetic waves, the angles of the CRFID sensor tag U3 in the electromagnetic shielding box U2 are rotatable through the turntable U4, and the backward scattering signal data under different angles are obtained by testing, so that the original electromagnetic signal level sample data set is obtained through the transformation processing of the bottom polar coordinate system data.
7. The system of claim 6, wherein the CRFID sensor tag U3 is configured to sense an electrical characteristic signal when the effective dielectric constant of the soil changes, process the electrical characteristic signal of the CRFID sensor tag U3, and derive a soil moisture identification model using the processed information.
8. The system of claim 7, wherein the electrical signature signal comprises: backscatter signal data, power, dielectric constant, resonant frequency, return loss.
9. The system of claim 8, wherein the CRFID sensor tag U3 is comprised of a shorted dipole structure whose resonant structure is used to backscatter an incident signal while embedding electromagnetic features in the form of resonance in the reflected signal.
10. The system of claim 9, wherein the vertical ridge antenna is configured to act as a transmitter to generate a vertically polarized interrogation signal and the horizontal ridge antenna is configured to act as a receiver to read a horizontally polarized signal backscattered from the sensor tag.
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