KR20240158780A - Moisture content measurement device, method and system through relative permittivity measurement based on electromagnetic waves - Google Patents

Abstract

One aspect of the present invention discloses a device, method, and system for measuring moisture content through relative permittivity measurement based on electromagnetic waves. The device includes a main body having one surface that can contact a medium and blocks external signals, an RF antenna that inputs a plurality of first electromagnetic waves (1 ^st electromagnetic waves) into the medium based on contact with the medium and receives a plurality of second electromagnetic waves (2 ^nd electromagnetic waves) reflected from the medium, and a microprocessor that measures input voltage signals (Vin) of the plurality of first electromagnetic waves and reception voltage signals (Vr) of the plurality of second electromagnetic waves to calculate a ratio of the plurality of input voltage signals and reception voltage signals, calculates relative permittivity for the medium based on the calculation result, and measures moisture content of the medium based on the calculated relative permittivity.

Description

{MOISTURE CONTENT MEASUREMENT DEVICE, METHOD AND SYSTEM THROUGH RELATIVE PERMITTIVITY MEASUREMENT BASED ON ELECTROMAGNETIC WAVES}

The present invention relates to a device and method for measuring a moisture content by measuring relative permittivity based on electromagnetic waves, and more specifically, to a device and method for measuring the permittivity of a medium using electromagnetic waves in the microwave (300 MHz to 300 GHz) band and obtaining the moisture content based thereon.

Concrete contains various materials. It includes sand, gravel, water, cement, etc., and the mixing of each material is very important to improve the quality of concrete. In particular, the amount of water in the concrete mix plays a very large role in the hardening speed and strength of the concrete.

Sand, gravel, etc. used in concrete are generally called aggregates, and the moisture content contained in these aggregates varies depending on the place where they were mined and how they were stored. Therefore, in order to obtain high-quality concrete, the amount of water added must be adjusted to reflect the moisture content of the aggregate added for proper mixing during concrete production.

Recently, there has been a lot of interest in measuring water content using electromagnetic waves. The method using electromagnetic waves is much more accurate than the existing gravimetric method, and much safer than the method using neutrons. This method uses the characteristics that the speed of electromagnetic waves changes depending on the water content contained in the aggregate when reflecting or transmitting electromagnetic waves, and the size and phase of the reflected electromagnetic waves change depending on the characteristics of the medium.

The method of measuring the water content using electromagnetic waves is to measure the relative permittivity of the medium, which varies according to the ratio of the water content. This method using electromagnetic waves uses microwaves from hundreds of MHz to several GHz. Generally, the electromagnetic waves created by the electromagnetic wave generator are transmitted to the antenna through the waveguide and radiated as electromagnetic waves through the antenna. The radiated electromagnetic waves are connected to each other as time-varying electric and magnetic fields and propagate.

Equation (1) below represents the general formula for electromagnetic waves existing in space.

k is a wave number vector that indicates the direction of time-varying propagation, and is determined by the permittivity (ε) and permeability (μ) of the medium through which the radio wave propagates and the frequency.

In general air, ε·μ=1/ ^c2 , where c is the same as the speed of light in air. It can also be seen that the propagation speed of electromagnetic waves in a dielectric, not in air, is slower than in air. In particular, in the case of a dielectric, the propagation speed of electromagnetic waves varies depending on the permittivity of the dielectric, so the permittivity of the dielectric can be obtained using the propagation speed of electromagnetic waves.

Also, in a space composed of two media based on a plane where z = 0, assuming that each medium is homogeneous, and if the space where z > 0 has medium 1 (ε ₁ , μ ₁ ) and the space where z < 0 has medium 2 (ε ₂ , μ ₂ ), when an electromagnetic wave is incident perpendicularly from medium 1 to medium 2, some of the incident electromagnetic waves are reflected and some are transmitted and propagated to medium 2. At this time, the magnitude (Γ) of the reflected electromagnetic wave can be defined as in equation (2) below according to the material properties of the two media.

Here, ε ₀ and μ ₀ represent the permitivity and permeability in air, and ε _{r_i} and μ _{r_i} represent the relative permitivity and relative permeability of each medium. In general, permittivity and permeability exist as complex numbers, and the real part is involved in the phase and magnitude of the electromagnetic wave, and the imaginary part is related to the loss of the electromagnetic wave.

Meanwhile, in the case where both the permeability and permittivity are real numbers and the material is not magnetic, the reflected signal can be simply obtained as in Equation (3) below when the relative permeability μ _{r_i} = 1.

For example, if the first medium is air (ε _{r_1} = 1) and the second medium is a dielectric with relative permittivity ε _{r_2} , the reflection value is negative. This means that the phases of the incident and reflected signals are opposite. Also, as ε _{r_2} increases, the absolute value of the reflected signal increases.

Meanwhile, it is known that the relative permittivity increases as the moisture content of the aggregate increases. The relationship is as follows. The formula is applicable only when the moisture content is 0.5 (50%) or less.

Meanwhile, there are several methods for measuring relative permittivity using electromagnetic waves. For example, there is a time domain reflectometry (TDR) method that measures the propagation speed of electromagnetic pulses in the time domain to find permittivity. The TDR method requires a metal probe that guides electromagnetic waves to propagate, and since time precision is very important, a circuit that measures precise time is required, and it is sensitive to noise caused by external communication signals, etc.

Or, there is FMCW (frequency modulated continuous wave), which is a method that transmits and receives signals by regularly modulating the phase in a certain band in the frequency domain and calculates the difference in the propagation speed of the radio waves. FMCW is less sensitive to external electromagnetic signals, but it must use the widest possible bandwidth to find precise propagation delay. In addition, a precise signal generator is required, and the transmitting and receiving antennas must be spaced apart from each other by a certain distance to allow signal separation, and although it is robust to narrowband external signals, the performance of the system may be degraded by signals with a bandwidth.

Therefore, we propose a method to solve the problems of FMCW and TDR method.

Korean Patent No. 10-0732471

The present invention is intended to solve the problems of the prior art as described above, and its purpose is to measure the permittivity of a medium using microwave electromagnetic waves and measure the moisture content based on the permittivity.

According to one aspect of the present invention, a moisture content measuring device through relative permittivity measurement based on electromagnetic waves is provided. The moisture content measuring device includes a main body having one surface that can contact a medium and blocks external signals, an RF antenna that inputs a plurality of first electromagnetic waves (1 ^st Electromagnetic Waves) into the medium based on contact with the medium and receives a plurality of second electromagnetic waves (2 ^nd Electromagnetic Waves) reflected from the medium, and a microprocessor that measures input voltage signals (Vin) of the plurality of first electromagnetic waves and reception voltage signals (Vr) of the plurality of second electromagnetic waves to calculate a ratio of the plurality of input voltage signals and reception voltage signals, calculates relative permittivity for the medium based on the calculation result, and measures moisture content of the medium based on the calculated relative permittivity.

In one aspect, the microprocessor calculates an interval of each of the plurality of input voltage signals and the received voltage signals, and measures the function quantity using the remainder except for at least one of the results of calculating the intervals that is not constant.

In another aspect, the main body is a metal box having a cylindrical or polyhedral shape, and the one side is a top surface of the cylindrical or polyhedral shape.

In another aspect, the RF antenna includes a signal input unit for inputting the plurality of first electromagnetic waves and a signal receiving unit for receiving the plurality of second electromagnetic waves.

In another aspect, the signal input section includes a ground in the shape of a disk or polyhedron and a metal core that inputs the plurality of first electromagnetic waves into the medium.

In another aspect, the signal receiving unit includes a metal conductor in the shape of a semicircle or polyhedron and a core wire provided inside the metal conductor to receive the plurality of second electromagnetic waves.

In another aspect, the plurality of first and second electromagnetic waves are a plurality of microwaves belonging to a frequency band between 300 MHz and 300 GHz.

In another aspect, the microprocessor calculates a first permittivity based on an input voltage signal and a received voltage signal of a first microwave selected within a microwave frequency band, calculates a second permittivity based on an input voltage signal and a received voltage signal of a second microwave selected within the microwave frequency band, and compares the first permittivity and the second permittivity to calculate the relative permittivity.

In another aspect, the microprocessor calculates a magnitude of an absolute value of the first permittivity and a magnitude of an absolute value of the second permittivity, and calculates a difference between the absolute value of the first permittivity and the absolute value of the second permittivity.

In another aspect, the microprocessor calculates an average of the first permittivity and the second permittivity and determines whether the relative permittivity converges within a range of the average.

In another aspect, if the microprocessor determines that the relative permittivity converges to the range of the average, it determines the functional amount corresponding to the relative permittivity as the functional amount of the medium.

In another aspect, if the microprocessor determines that the relative permittivity does not converge within the range of the average, it recalculates the relative permittivity using microwaves of a different frequency from that used to calculate the relative permittivity.

In another aspect, the first frequency band and the second frequency band are non-contiguous frequency bands.

In another aspect, the RF antenna changes the frequency of at least one of the plurality of first electromagnetic waves and inputs it into the medium, and receives an electromagnetic wave reflected from the medium.

In another aspect, it further includes a communication unit that transmits the result of measuring the above functional quantity to a server.

According to another aspect of the present invention, a method for measuring a water content by measuring a relative permittivity based on an electromagnetic wave is provided. The method for measuring a water content includes the steps of: inputting a plurality of first electromagnetic waves into a medium while blocking an external signal and in contact with the medium; receiving a plurality of second electromagnetic waves reflected from the medium; measuring input voltage signals of the plurality of first electromagnetic waves and reception voltage signals of the plurality of second electromagnetic waves to calculate a ratio of the plurality of input voltage signals and the reception voltage signals; calculating a relative permittivity for the medium based on the calculation result; and measuring the water content of the medium based on the calculated relative permittivity.

According to another aspect of the present invention, a system for measuring a water content by measuring a relative permittivity based on electromagnetic waves is provided. The system for measuring a water content includes a water content measuring sensor which blocks an external signal, inputs a plurality of first electromagnetic waves into a medium while in contact with the medium, receives a plurality of second electromagnetic waves reflected from the medium, measures input voltage signals of the plurality of first electromagnetic waves and reception voltage signals of the plurality of second electromagnetic waves to calculate a ratio of the plurality of input voltage signals and the reception voltage signals, calculates a relative permittivity for the medium based on the calculation result, and measures a water content of the medium based on the calculated relative permittivity, and a server which receives a result of measuring the water content of the medium from the sensor.

In one aspect, the server includes a data analysis algorithm learned to verify the functional content based on big data related to the functional content measurement, and verifies the result of measuring the functional content of the medium using the data analysis algorithm.

Embodiments of the present invention may have effects including the following advantages. However, it should not be understood that the embodiments of the present invention should include all of these, and thus the scope of the rights of the present invention should not be limited thereby.

A device for measuring a water content by measuring a relative permittivity based on an electromagnetic wave according to one embodiment of the present invention can effectively measure a water content by measuring a relative permittivity.

FIG. 1 is a drawing for explaining a relative permittivity measurement method using multiple frequencies in a function amount measurement method according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of a system for measuring a functional quantity through relative permittivity measurement based on electromagnetic waves according to one embodiment of the present invention.
Figure 3 is a drawing showing the signal input section and signal output section of an RF antenna.
Figure 4 is a cross-sectional drawing showing the signal input section and signal output section of the RF antenna.
FIG. 5 is a drawing showing an example of a combination of a GND, a metal conductor, and a center GND and a metal conductor for signal input in a function amount measuring device according to an embodiment of the present invention.
Figure 6 is a drawing showing the single-layer structure of Figure 5 expanded into a double-layer structure.
Figure 7 is a diagram showing the operating principle of an RF antenna.
Figure 8 is a circuit diagram showing monitoring the ratio and phase difference between an input voltage signal and a received voltage signal.
FIG. 9 is a flowchart showing a method for measuring a functional content by measuring relative permittivity based on electromagnetic waves according to one embodiment of the present invention.

The present invention can have various modifications and embodiments, and specific embodiments are illustrated in the drawings and described in detail.

However, this is not intended to limit the present invention to specific embodiments, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are only used to distinguish one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and/or includes any combination of a plurality of related described items or any item among a plurality of related described items.

When it is said that a component is "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components in between. On the other hand, when it is said that a component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprises" or "has" and the like are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms defined in commonly used dictionaries, such as those defined in common dictionaries, should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

Hereinafter, with reference to the attached drawings, a preferred embodiment of the present invention will be described in more detail. In order to facilitate an overall understanding in describing the present invention, the same reference numerals are used for the same components in the drawings, and redundant descriptions of the same components are omitted.

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. However, some components that are irrelevant to the gist of the invention will be omitted or compressed. However, the omitted components do not necessarily mean that they are not necessary for the present invention, and can be combined and used by a person having ordinary knowledge in the technical field to which the present invention belongs.

Electromagnetic waves have different characteristics of reflection and transmission depending on the permittivity of the medium. For example, when the water content is large, the relative permittivity is high, so the amount of reflection is large and the amount of transmission is small. The present invention proposes a method of using a method of measuring the relative permittivity by only comparing the size of the transmission and reception signals of multiple electromagnetic waves in a certain band.

FIG. 1 is a drawing for explaining a relative permittivity measurement method using multiple frequencies in a function amount measurement method according to an embodiment of the present invention.

Referring to Fig. 1, each graph presented represents the ratio of the input voltage signal (Voltage in, Vin) and the received voltage signal (Voltage receive, Vr) according to the frequency in a configuration in which a signal is input through an RF antenna and a reflected signal is received for a medium with different relative permittivity. As in Fig. 1, the ratio of the transmitted signal to the received signal gradually decreases as the relative permittivity increases. In other words, the ratio of the transmitted signal to the received signal gradually decreases as the functional content increases. For example, as in Fig. 1, the functional content ε _r4 has the largest value, When the functional content ε _r1 is the smallest, the relative permittivity ε ₄ can be the smallest, and the relative permittivity ε ₁ can be the largest. In other words, the functional content and the relative permittivity can have the characteristic of being inversely proportional to each other.

In addition, the relative permittivity can be measured using multiple frequencies, and even if the frequency changes, the difference in the relative permittivity is not large, and the interval of the difference in the relative permittivity tends to be constant. By utilizing this feature that the absolute value of the ratio of the two signals has a constant difference according to the difference in the relative permittivity, the relative permittivity can be calculated using the ratio of the input voltage signal and the received voltage signal.

Such characteristics are determined by the characteristics of the medium and can be thought of as eigenvalues of the medium. In other words, the relative permittivity, which is the same physical value, can be obtained regardless of the measurement method.

For example, by measuring the ratio of a transmitted signal (input voltage signal) and a received signal (received voltage signal) in the air and measuring the permittivity of a material whose relative permittivity is known, the relative permittivity of any target material can be measured.

Alternatively, the relative permittivity can be measured based on input values through a pre-test.

This method does not require the use of continuous signals like conventional FMCW. In particular, it can be used while changing the frequency of use, so it is also strong against external noise characteristics. In addition, it can be designed by avoiding parts that have band-pass or band-reflection characteristics at specific frequencies that are created by the structural characteristics of the antenna.

From a signal processing perspective, if the relative permittivity obtained at multiple frequencies is used, the error in the relative permittivity obtained at only one frequency can be minimized by comparing the relative permittivity values obtained at each of the multiple frequencies with each other or by using the average.

FIG. 2 is a schematic diagram of a system for measuring a functional quantity through relative permittivity measurement based on electromagnetic waves according to one embodiment of the present invention.

Referring to FIG. 2, a water content measurement system (200) using relative permittivity measurement based on electromagnetic waves may include a water content measurement device (110) and a server (120).

The moisture content measuring device (110) is a device that calculates the relative permittivity of a medium and measures the moisture content of the medium based on the calculated relative permittivity. The moisture content measuring device (110) may include a main body that blocks external signals, an RF antenna that inputs electromagnetic waves to a medium and receives electromagnetic waves reflected from the medium, and a microprocessor that measures an input voltage signal of an electromagnetic wave input to the medium and a reception voltage signal of an electromagnetic wave reflected from the medium to calculate a ratio of a plurality of input voltages and reception voltages, calculates the relative permittivity for the medium based on the calculated relative permittivity, and measures the moisture content of the medium based on the calculated relative permittivity. The moisture content measuring device (110) may be implemented as a sensor that measures the moisture content.

Below, each component of the function measurement device (110) is described.

The main body includes a medium contact surface on one side. The user of the function amount measuring device (110) can contact the medium contact surface of the main body with the medium by touching the main body with the medium by hand or connecting it to a separate device or apparatus. The medium contact surface of the main body can be formed on the top surface of the body, and signals such as electromagnetic waves, electromagnetic waves, and microwaves transmitted from the outside can be blocked due to the metal material.

Meanwhile, the main body may be implemented as a metal box having a cylindrical or polyhedral shape. Accordingly, the shape or size of the medium contact surface of the main body may vary depending on the shape of the main body. For example, if the main body is implemented as a cylindrical shape, the medium contact surface of the main body may also be formed as a circular surface.

The RF antenna inputs a plurality of first electromagnetic waves into the medium while the main body is in contact with the medium. Then, it receives a plurality of second electromagnetic waves reflected from the medium. The plurality of first electromagnetic waves can be input into the medium through a signal input unit of the RF antenna. The plurality of second electromagnetic waves can be received through a signal receiving unit of the RF antenna. That is, the first electromagnetic waves may correspond to the input voltage signal of FIG. 1, and the second electromagnetic waves may correspond to the reception voltage signal of FIG. 1. The first electromagnetic waves and the second electromagnetic waves may be a plurality of microwaves belonging to a frequency band between 300 MHz and 300 GHz. The RF antenna can input the medium by changing the frequency of at least one of the plurality of first electromagnetic waves and receive the electromagnetic wave reflected from the medium. The change in frequency can be performed within a microwave frequency band. In other words, the RF antenna can transmit a plurality of first electromagnetic waves belonging to the microwave frequency band to a medium and receive second electromagnetic waves reflected from the medium.

A microprocessor measures input voltage signals of a plurality of first electromagnetic waves and reception voltage signals of a plurality of second electromagnetic waves to calculate a ratio of the plurality of input voltage signals and the reception voltage signals. The microprocessor calculates a relative permittivity for a medium based on the calculated relative permittivity, and measures a moisture content of the medium based on the calculated relative permittivity.

In order to measure a more accurate amount of function, the microprocessor can calculate the intervals of each of the ratios of a plurality of input voltage signals and received voltage signals, and exclude at least one whose calculated intervals are not constant. Here, the interval refers to a calculated value obtained by comparing the ratios of the input voltage signals and received voltage signals of a specific frequency band with the ratios of the input voltage signals and received voltage signals of another frequency band. That is, the ratios of the input voltage signals and received voltage signals are calculated for each frequency for a plurality of electromagnetic waves, and the intervals are compared to determine that the interval differences are not constant as errors and can be excluded. The microprocessor can measure the amount of function by using the remainder after excluding the values with errors through this process.

Meanwhile, the microprocessor can calculate the frequency-specific permittivity by calculating the ratio of the input voltage signal and the received voltage signal for each frequency. For example, the first permittivity can be calculated based on the input voltage signal and the received voltage signal of the first microwave (microwave of the first frequency band) selected within the microwave frequency band. And, the second permittivity can be calculated based on the input voltage signal and the received voltage signal of the second microwave (microwave of the second frequency band) selected within the microwave frequency band. The microprocessor can calculate the relative permittivity for the medium by comparing the first permittivity and the second permittivity. Here, the first frequency band and the second frequency band may be frequency bands that belong to the microwave frequency band but are not continuous with each other. That is, the first permittivity and the second permittivity may be permittivities calculated from signals of frequency bands arbitrarily selected within the microwave band, not permittivities for continuous frequencies. The microprocessor can calculate a magnitude of an absolute value of the first permittivity and a magnitude of an absolute value of the second permittivity, and calculate a difference between the absolute value of the first permittivity and the absolute value of the second permittivity to calculate a relative permittivity between the first permittivity and the second permittivity.

Meanwhile, the microprocessor can calculate the average of the first permittivity and the second permittivity, and determine whether the relative permittivity between the first permittivity and the second permittivity converges to the range of the average. The microprocessor can minimize the occurrence of errors in the measurement of the relative permittivity by comparing the relative permittivity obtained from a plurality of frequencies with each other or with the average. Here, the average can be calculated directly, or the average value of the relative permittivity for each medium can be obtained and used from the connected server (120). If the microprocessor determines that the relative permittivity converges to the range of the average, the microprocessor can determine the functional amount corresponding to the relative permittivity as the functional amount of the medium. If the microprocessor determines that the relative permittivity does not converge to the range of the average, the microprocessor can recalculate the relative permittivity using a microwave of a different frequency from the frequency used to calculate the relative permittivity. That is, a microwave whose frequency has been changed can be input and received through an RF antenna.

Meanwhile, the function amount measuring device (110) may further include a communication unit that transmits the result of measuring the function amount to the server (120). The communication unit may transmit the result of measuring the function amount to the server (120) using serial communication such as RS485. In addition, depending on the situation, data necessary for measuring the function amount may be received from the server (120).

The server (120) is a device that receives the results of measuring the water content. The server (120) may be equipped with a dedicated UI (User Interface) that outputs the results of measuring the water content. For example, the results measured from a sensor (water content measuring device) may be analyzed using the dedicated UI to produce data for measuring a more precise water content. This UI may be implemented as an HMI (Human Machine Interface) that applies the water content measured from the sensor to the production mixing ratio in real time in conjunction with a production program. For example, the mixing ratio corresponding to the measured water content may be automatically adjusted and reflected in the production process.

Meanwhile, the server (120) may include a data analysis algorithm learned to verify the functional content based on big data related to the functional content measurement. The server (120) may verify the result of measuring the functional content of the medium using the data analysis algorithm. The server (120) may be implemented as a PC, a laptop, a PDA, a smartphone, etc. The server (120) described below is described as an example of a PC, but other types of devices described above may also be applied.

Figure 3 is a drawing showing the signal input section and signal output section of an RF antenna.

FIG. 3 is a top view of an RF antenna, and referring to FIG. 3, the RF antenna includes a signal input unit and a signal receiving unit, and the signal input unit and the signal receiving unit are provided inside a metal box for blocking external signals. The signal input unit includes a round disc-shaped ground (GND) and a metal core for inputting a first electromagnetic wave into a medium. As shown in FIG. 3, the metal core is located at the center of the ground. The signal receiving unit includes a semicircular metal conductor similar to the shape of the metal box and a core wire for receiving a second electromagnetic wave. The metal core wire for signal reception is connected to a specific position of the metal conductor. The semicircular metal conductor is electrically conductive with the metal box. In the example of FIG. 3, the ground of the signal input unit is described as having a disc shape and the metal conductor of the signal receiving unit is described as having a semicircular shape, but these may also be provided in a polyhedral shape.

Figure 4 is a cross-sectional drawing showing the signal input section and signal output section of the RF antenna.

FIG. 4(a) shows the inside of the main body cut vertically based on the signal input section, and FIG. 4(b) shows a vertical cut surface including both the signal input section and the signal receiving section. First, referring to FIG. 4(a), there is a cylindrical metal tube (main body), and an input signal (first electromagnetic wave) is input through a signal input section having a coaxial structure. The center of the cylindrical metal groove has upper and lower discs, and each disc is connected by a via. A hole of a certain size must be formed in the center of the disc so that the core wire of the signal input section can be input. It is connected to the disc, and a semicircular metal conductor is connected along the edge of the cylindrical metal groove. The end of the semicircular metal conductor is connected to the cylindrical metal tube.

Fig. 4b is a cross-sectional view of a portion including a receiving unit. As in Fig. 4b, the core metal of the receiving unit is connected to a certain position of a semicircular metal conductor, and a signal (second electromagnetic wave) is transmitted through the bottom of the cylindrical metal tube. For signal transmission, it is preferable that the bottom of the metal box be configured in a coaxial shape as in Fig. 4b. In order to receive the receiving signal (second electromagnetic wave), the bottom of the cylindrical metal tube has a core metal and a ground portion like a coaxial line, and the core metal is connected to the semicircular metal conductor.

As in Fig. 4, the RF antenna shape may be a single antenna with the positions of the signal input section and the signal output section separated.

It is desirable that the core metal for signal input be slightly above GND.

In addition, it is desirable to place a solid protective dielectric between the medium and the antenna pattern, which has a relative permittivity greater than that of the metal box and a relative permittivity greater than that of the maximum medium to be measured. This dielectric is in direct contact with the medium to be measured. It can stably receive signals even if the characteristics of the medium change.

In addition, as in the cross section, it is desirable to place the disc-shaped GND and the input signal metal core wire close to the protective dielectric. Through this, signal input can be efficiently performed, and the input signal can be transmitted through the medium so that the characteristics of the medium to be measured can be effectively included in the received signal.

FIG. 5 is a drawing showing an example of a combination of a ground (GND), a metal conductor, and a center ground and a metal conductor for signal input in a function amount measuring device according to an embodiment of the present invention. FIG. 5 a shows the shape of the center ground, b shows the shape of the outer receiving conductor, and c shows the shape of the center ground and the outer receiving conductor combined.

Referring to Figures 5a to c, the conductor may be a semicircle or a polyhedron, depending on the shape of the metal box for blocking external signals, etc. In addition, various combinations are possible. That is, examples of combinations of a circular ground and a square outer shape, a circular ground and a semicircular outer conductor, etc. are possible. It is advantageous to make both the circular and semicircular metal conductors integrally using a printed circuit board.

Figure 6 is a drawing showing the single-layer structure of Figure 5 expanded into a double-layer structure.

Figure 6(a) shows the shape of the center ground of the double-layer structure, figure 6(b) shows the shape of a single conductor combined with the ground of the double-layer structure, and figure 6(c) shows the shape of a double-layer conductor combined with the double-layer ground.

First, referring to Fig. 6a, this is a method of implementing GND on the upper and lower surfaces in an antenna system having a double layer. As in Fig. 6a, the upper and lower surfaces are connected by a via (via hole), and the center is opened to a certain size for a core metal. The interior can also be filled with a dielectric.

Fig. 6b is an example of a transmitting/receiving antenna system applied to a double-layer structure using the single-layer structure of Fig. 5. As shown in the drawing, the upper surface is the same as the single-layer structure.

Figure 6c uses the proposed configuration in a single-layer structure on both sides, with the upper and lower surfaces connected by vias.

In addition to this, the double-layer structure can have various shapes. Using a double-layer structure, the reception signal can be received more stably.

Figure 7 is a diagram showing the operating principle of an RF antenna.

Referring to Fig. 7, the electromagnetic wave propagates through the protective substrate to a location with a dielectric constant, and some of the propagated signal penetrates the medium and is re-injected into port 2. The received signal also includes a signal that is reflected by the medium through the protective substrate. At this time, the intensity of the received signal is smaller as the dielectric constant is higher or the water content is larger. The curve shown on the right side of Fig. 7 shows the shape of the electromagnetic wave being incident on the dielectric using an RF antenna.

Figure 8 is a circuit diagram showing monitoring the ratio and phase difference between an input voltage signal and a received voltage signal.

Referring to Fig. 8, by inputting a transmission signal and a reception signal, the ratio of the transmission signal and the reception signal can be obtained, and also, this value can be subject to an operation such as Log. In addition, by using the product of the two signals, the phase difference (Vph) of the two signals can be obtained.

FIG. 9 is a flowchart showing a method for measuring a functional content by measuring relative permittivity based on electromagnetic waves according to one embodiment of the present invention.

Referring to Fig. 9, the water content measurement method includes steps S910 to S950. The water content measurement method according to the present embodiment is explained by the operation of the water content measurement sensor (110) described through Fig. 2.

At step S910, the function measuring device (110) blocks external signals and inputs a plurality of first electromagnetic waves into the medium while in contact with the medium.

At step S920, the function measuring device (110) receives a plurality of second electromagnetic waves reflected from the medium.

At step S930, the function measuring device (110) measures the input voltages of a plurality of first electromagnetic waves and the reception voltages of a plurality of second electromagnetic waves to calculate a ratio of the plurality of input voltages and the reception voltages.

At step S940, the function measuring device (110) calculates the relative permittivity for the medium based on the output result.

At step S950, the function amount measuring device (110) measures the function amount of the medium based on the calculated relative permittivity.

Meanwhile, although the above-described steps S910 to S950 have been described as operations of the function amount measuring device (110), some of them may be described as operations of the server (120) described through FIG. 2. For example, the server (120) may receive information on the first electromagnetic wave and the second electromagnetic wave from the function amount measuring device (110) and perform steps S930 to S950 instead.

Although the present invention has been described with reference to the above drawings and embodiments, it does not mean that the scope of protection of the present invention is limited by the above drawings or embodiments, and it will be understood that a person skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention as described in the following claims.

Claims (18)

In a device for measuring the amount of water by measuring relative permittivity based on electromagnetic waves,
A main body having one side that can come into contact with a medium and blocks external signals;
An RF antenna that inputs a plurality of first electromagnetic waves (1 ^st Electromagnetic Waves) into the medium based on contact with the medium and receives a plurality of second electromagnetic waves (2 ^nd Electromagnetic Waves) reflected from the medium; and
A moisture content measuring device including a microprocessor that measures input voltage signals (Vin) of the plurality of first electromagnetic waves and reception voltage signals (Vr) of the plurality of second electromagnetic waves to calculate a ratio of the plurality of input voltage signals and reception voltage signals, calculates relative permittivity for the medium based on the calculated result, and measures moisture content of the medium based on the calculated relative permittivity. In paragraph 1,
A function measuring device, wherein the microprocessor calculates the intervals of each of the plurality of input voltage signals and the received voltage signals, and measures the function amount using the remainder except for at least one of the intervals for which the results of calculating the intervals are not constant. In paragraph 1,
A water content measuring device, wherein the main body is a metal box in the shape of a cylinder or polyhedron, and the one side is the top surface of the cylinder or polyhedron. In paragraph 1,
The RF antenna has a signal input section for inputting the plurality of first electromagnetic waves; and
A function amount measuring device comprising a signal receiving unit that receives the plurality of second electromagnetic waves. In paragraph 4,
The above signal input section is a ground in the shape of a disk or polyhedron; and
A function measuring device comprising a metal core that inputs the plurality of first electromagnetic waves into the medium. In paragraph 4,
The above signal receiving unit is a metal conductor in the shape of a semicircle or polyhedron; and
A function measuring device comprising a core wire provided inside the metal conductor and receiving the plurality of second electromagnetic waves. In paragraph 1,
A function measuring device, wherein the plurality of first and second electromagnetic waves are a plurality of microwaves belonging to a frequency band between 300 MHz and 300 GHz. In paragraph 1,
A function measuring device, wherein the microprocessor calculates a first permittivity based on an input voltage signal and a reception voltage signal of a first microwave selected within a microwave frequency band, calculates a second permittivity based on an input voltage signal and a reception voltage signal of a second microwave selected within the microwave frequency band, and calculates the relative permittivity by comparing the first permittivity and the second permittivity. In Article 8,
A function measuring device, wherein the microprocessor calculates the magnitude of the absolute value of the first permittivity and the magnitude of the absolute value of the second permittivity, and calculates the difference between the absolute value of the first permittivity and the absolute value of the second permittivity. In Article 8,
A function measuring device, wherein the microprocessor calculates an average of the first permittivity and the second permittivity and determines whether the relative permittivity converges within the range of the average. In Article 10,
If the microprocessor determines that the relative permittivity converges to the range of the average, it determines the functional amount corresponding to the relative permittivity as the functional amount of the medium. In Article 10,
If the microprocessor determines that the relative permittivity does not converge to the range of the average, it recalculates the relative permittivity using microwaves of a different frequency from the frequency used to calculate the relative permittivity. In Article 8,
A function amount measuring device, wherein the first frequency band and the second frequency band are non-contiguous frequency bands. In paragraph 1,
A function measuring device, wherein the RF antenna changes the frequency of at least one of the plurality of first electromagnetic waves and inputs it into the medium, and receives an electromagnetic wave reflected from the medium. In paragraph 1,
A device for measuring the amount of function, further comprising a communication unit that transmits the result of measuring the amount of function to a server. In a method for measuring the amount of function by measuring relative permittivity based on electromagnetic waves,
A step of blocking an external signal and inputting a plurality of first electromagnetic waves into a medium while in contact with the medium;
A step of receiving a plurality of second electromagnetic waves reflected from the above medium;
A step of measuring input voltage signals of the plurality of first electromagnetic waves and reception voltage signals of the plurality of second electromagnetic waves to calculate a ratio of the plurality of input voltage signals and reception voltage signals;
A step of calculating the relative permittivity for the medium based on the output results; and
A method for measuring a water content, comprising the step of measuring the water content of the medium based on the calculated relative permittivity. In a function measurement system using relative permittivity measurement based on electromagnetic waves,
A moisture content measuring sensor that blocks external signals, inputs a plurality of first electromagnetic waves into the medium while in contact with the medium, receives a plurality of second electromagnetic waves reflected from the medium, measures input voltage signals of the plurality of first electromagnetic waves and reception voltage signals of the plurality of second electromagnetic waves to calculate a ratio of the plurality of input voltage signals and the reception voltage signals, calculates a relative permittivity for the medium based on the calculation result, and measures the moisture content of the medium based on the calculated relative permittivity; and
A water content measurement system including a server that receives the results of measuring the water content of the medium from the sensor. In Article 17,
A system for measuring the amount of water, wherein the server includes a data analysis algorithm learned to verify the amount of water based on big data related to the measurement of the amount of water, and verifies the result of measuring the amount of water of the medium using the data analysis algorithm.

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