Soil sensor

Abstract

A soil sensor (30) is provided with a first signal line (51) that transmits high-frequency electromagnetic waves, and a porous body part (60) that has water permeability and water retention. The soil sensor (30) is provided with: a second signal line (61) that transmits low-frequency electromagnetic waves and faces the soil with the porous body therebetween; and ground lines (52, 62) that are disposed further toward the inside than the first signal line. The second signal line (61) is disposed further inward than the first signal line (51) and the ground lines (52, 62). As a result, it is possible to suppress the influence of the electric field formed by one of the first signal line (51) and the second signal line (61) on the other signal line.

Description

[0001] Cross-reference of related applications

[0002] This application is based on patent application No. 2022-091822 filed in Japan on June 6, 2022, and the contents of the basic application are incorporated herein by reference in their entirety. Technical Field

[0003] The disclosure of this specification relates to a soil sensor for detecting the state of soil. Background Art

[0004] Patent Document 1 discloses a soil sensor that simultaneously measures the water potential and volumetric water content of soil.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: U.S. Patent No. 7042234 Summary of the invention

[0008] The soil sensor described above switches between high-frequency mode and low-frequency mode using the same probe electrode to detect volumetric water content and water potential. For example, since the water content of porous bodies is also included in the detection range when detecting in the high-frequency mode, there is a problem that the detection error of the water content of the soil to be detected may occur.

[0009] An object of the disclosure of this specification is to provide a soil sensor capable of reducing a detection error of soil moisture content.

[0010] The multiple embodiments disclosed in this specification adopt different technical means to achieve their respective purposes. In addition, the symbols in parentheses recorded in the claims are an example of the correspondence relationship with the specific means described in the embodiments described later as one embodiment, and are not used to limit the technical scope.

[0011] One of the disclosed soil sensors comprises a first signal line that transmits high-frequency electromagnetic waves and faces the soil, a porous body portion having water permeability and water retention, a second signal line that transmits low-frequency electromagnetic waves having a frequency lower than the high frequency and faces the soil across the porous body portion, and a ground line that is arranged on the inner side than the first signal line; the second signal line is arranged on the inner side than the first signal line and the ground line.

[0012] The soil sensor is provided with a second signal line for transmitting a relatively low-frequency electromagnetic wave inside a first signal line for transmitting a high-frequency electromagnetic wave. Furthermore, by providing a ground line between the first signal line and the second signal line, the influence of the electric field formed by the high-frequency electromagnetic wave on the second signal line can be suppressed. In addition, the influence of the electric field formed by the low-frequency electromagnetic wave on the first signal line can also be suppressed. Therefore, according to this technology, a soil sensor capable of reducing the detection error of soil moisture can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a control structure diagram of the soil sensor including the first embodiment.

[0014] Figure 2 It is a diagram showing the structure of a soil sensor.

[0015] Figure 3 It is a schematic cross-sectional view showing the positional relationship between the first detection section and the second detection section in the soil sensor.

[0016] Figure 4 It is a diagram showing another example of the porous body portion according to the first embodiment.

[0017] Figure 5 It is a diagram showing the structure of a soil sensor according to a second embodiment.

[0018] Figure 6 It is a schematic cross-sectional view showing the positional relationship between the first detection section and the second detection section in the soil sensor.

[0019] Figure 7 It is a partial cross-sectional view of a base portion in the soil sensor according to the third embodiment.

[0020] Figure 8 It is a diagram showing the structure of a soil sensor according to a fourth embodiment.

[0021] Fig. 9 It is a diagram showing a first example of the soil sensor according to the fifth embodiment.

[0022] Fig.10 It is a diagram showing a second example of the soil sensor according to the fifth embodiment.

[0023] Fig.11 It is a diagram showing a third example of the soil sensor according to the fifth embodiment.

[0024] Fig.12 It is a diagram showing a fourth example of the soil sensor according to the fifth embodiment.

[0025] Fig.13 It is a diagram showing a fifth example of the soil sensor according to the fifth embodiment.

[0026] Fig.14 It is a diagram showing a sixth example of the soil sensor according to the fifth embodiment.

[0027] Fig.15 It is a partial cross-sectional view showing the sealing structure of the base portion and the casing portion according to the sixth embodiment.

[0028] Fig.16 It is a cross-sectional view showing a supporting structure of a porous body according to a seventh embodiment.

[0029] Fig.17 It is a cross-sectional view showing a first example of the structure of the base portion according to the eighth embodiment.

[0030] Fig.18 It is a cross-sectional view showing a second example of the structure of the base portion according to the eighth embodiment.

[0031] Fig.19 It is a diagram for explaining the abnormality determination process of the soil sensor according to the ninth embodiment.

[0032] Fig. 20 It is a diagram for explaining the abnormality determination process of the soil sensor according to the tenth embodiment.

[0033] Fig.21 It is a diagram for explaining the abnormality determination process of the soil sensor according to the tenth embodiment. DETAILED DESCRIPTION

[0034] The following describes a plurality of embodiments for implementing the present disclosure with reference to the accompanying drawings. With respect to each embodiment, portions corresponding to matters described in a previous embodiment are given the same reference numerals and repeated descriptions may be omitted. With respect to each embodiment, when only a portion of a structure is described, other embodiments previously described may be applied to other portions of the structure. Not only are combinations of parts that can be combined specifically indicated in each embodiment, but embodiments may also be partially combined with each other even without explicit indication, as long as no particular obstacles are created in the combination.

[0035] First Embodiment

[0036] Reference Figure 1 to Figure 4The first embodiment of an example of a disclosed soil sensor is described. The irrigation system includes a water supply device and a control device 100. The water supply device supplies irrigation water to plants in a field. The water supply device includes a pump, a water supply pipe, etc. The pump functions as a water supply source that causes the irrigation water to flow down the water supply pipe. When irrigation is implemented, the control device 100 controls the irrigation according to the supply time and the amount of irrigation water supplied from the water supply device to the plants. The control device 100 performs feedback control on the valve opening of the water supply valve 16 using the detection value of the water pressure sensor 15. The water supply valve 16 controls the flow rate of the irrigation water sprayed from the water supply pipe by controlling the valve opening by the controlled device 100.

[0037] like Figure 1 As shown in FIG. 1 , the control device 100 includes an acquisition unit 11, a signal output unit 12, a storage unit 13, and a processing unit 14. In the figure, the acquisition unit 11 is marked as AD, the signal output unit 12 is marked as SOU, the storage unit 13 is marked as MU, and the processing unit 14 is marked as PU. The acquisition unit 11 receives an environmental value detected by the soil sensor 30. The acquisition unit 11 receives a water pressure detected by the water pressure sensor 15 and a valve opening of the water supply valve 16.

[0038] The signal output unit 12 is electrically connected to the water supply valve 16. A control signal for controlling the valve opening of the water supply valve 16 is output from the signal output unit 12 to the water supply valve 16.

[0039] The storage unit 13 is a non-movable physical storage medium that non-temporarily stores programs and data that can be read by a computer or a processor. The storage unit 13 has a volatile memory and a non-volatile memory. The storage unit 13 stores a program for the processing unit 14 to perform arithmetic processing. The storage unit 13 temporarily stores data when the processing unit 14 performs arithmetic processing. The storage unit 13 stores various data input to the acquisition unit 11 and the acquisition time of the various data.

[0040] like Figure 2 As shown, the soil sensor 30 includes a detection unit 1 and a housing 2. The detection unit 1 is a portion buried in the soil of a field. The housing 2 is buried in the soil or is not buried in the soil but is arranged outside the soil. The housing 2 has a built-in circuit unit including a CPU. The circuit unit includes a processing unit 31 that performs calculations using data detected by the detection unit of the soil sensor 30, and a communication unit 32 that communicates with the control device 100. The housing 2 may also be a structure in which a thermistor capable of measuring temperature is built-in. The irrigation system that controls irrigation of the soil monitors the soil moisture content through the soil sensor 30, and determines whether irrigation is needed or ended based on the detected value.

[0041] The detection unit 1 includes a first detection unit 5 and a second detection unit 6. The first detection unit 5 includes a first signal line 51 and a ground line 52. The second detection unit 6 includes a second signal line 61, a ground line 62, and a porous body 60. The detection unit 1 includes a first signal line 51, a second signal line 61, a porous body 60, and a base 4.

[0042] The circuit unit built in the housing 2 applies a frequency signal corresponding to a high frequency band within a specified range between the end of the first signal line 51 and the end of the ground line 52. The circuit unit applies a frequency signal corresponding to a low frequency band within a specified range between the end of the second signal line 61 and the end of the ground line 62. High-frequency electromagnetic waves such as microwaves are transmitted in the first signal line 51. Low-frequency electromagnetic waves having a frequency smaller than that of the electromagnetic waves transmitted in the first signal line 51 are transmitted in the second signal line 61.

[0043] Preferably, the frequency of the electromagnetic wave transmitted in the first signal line 51 is set to a frequency band that is 100 times or more higher than the frequency of the electromagnetic wave transmitted in the second signal line 61. This frequency relationship greatly helps to avoid mutual influence between the electric field generated by one signal line and the electric field generated by the other signal line.

[0044] Preferably, the base 4 is formed of a water-impermeable material, for example, so that water does not enter the base 4. At least the surface of the base 4 is an insulator to avoid short circuits between the first signal lines 51, between the second signal lines 61, and between the first signal line 51 and the second signal line 61.

[0045] The base 4 is formed of, for example, acrylic or other resin materials. The base 4 may also be a structure obtained by insulating the surface of a substrate formed of a metal such as aluminum or iron. The base 4 is a plate-like shape whose thickness is smaller than its width and length. The base 4 may also be a component called a so-called printed circuit board. In addition, the shape of the base 4 may also be other shapes.

[0046] like Figure 3 As shown, a first signal line 51 and a ground line 52 are provided on a surface on one side in the thickness direction TD of the base portion 4. A first signal line 51 and a ground line 52 are provided on a surface on the other side in the thickness direction TD of the base portion 4. The first signal line 51 and the ground line 52 are provided on both surfaces of the base portion 4 in the thickness direction TD with the same structure. Figure 3 , the surface side on one side in the thickness direction TD is marked as FS, and the back side on the other side is marked as BS. The first signal line 51 is in direct contact with the soil. The first signal line 51 is arranged outside the ground line 52 in a manner that surrounds the ground line 52 on the outside. The ground line 52 is arranged along the first signal line 51 at a certain interval inside the first signal line 51.

[0047] The first signal line 51 and the ground line 52 include a return line located at the front end side portion 4f of the base portion 4 and a shell side line located at the root side portion 4r of the base portion 4. The return line and the shell side line are connected to form a continuous first signal line 51. The return line is a line connecting a portion extending from the shell side to the front end side and a portion extending from the shell side to the front end side. The first signal line 51 is as shown in FIG. Figure 2 As shown, it has a pair of return lines adjacent to each other in the width direction of the base portion 4. The first signal line 51 has a pair of shell side lines arranged in the width direction of the base portion 4. The width direction is a direction orthogonal to both the thickness direction TD and the length direction LD of the base portion 4. The first signal line 51 has a plurality of return portions on the surface side of the base portion 4 and is formed into a loop shape.

[0048] like Figure 3 As shown, the second signal line 61 and the ground line 62 are provided on the surface on the other side in the thickness direction TD of the base portion 4. The second signal line 61 and the ground line 62 are provided on the surface on the other side in the thickness direction TD of the base portion 4. The first signal line 51 and the ground line 52 are provided on the surface and the back side in the thickness direction TD of the base portion 4 in the same structure. The second signal line 61 and the ground line 62 are provided in a manner located between a pair of shell portion side lines.

[0049] The second signal line 61 is located inside relative to the first signal line 51. The second signal line 61 is surrounded by the first signal line 51 on the outside, and is arranged on the inside of the first signal line 51. A ground line 52 and a ground line 62 are provided between the second signal line 61 and the first signal line 51. The second signal line 61 is surrounded by the ground line 62 on the outside, and is arranged on the inside of the ground line 62. The second signal line 61 is surrounded by the ground line 52 on the outside, and is arranged on the inside of the ground line 52. The second signal line 61 is arranged at a position that can avoid the area of ​​the electric field formed and extended by the first signal line 51 and the ground line 52. Therefore, the second signal line 61 and the first signal line 51 can suppress the situation where the electric field formed on one side affects the signal line of the other side.

[0050] The second signal line 61 is covered by a porous body 60 having a large number of pores. The porous body 60 is formed of a material having water permeability and water retention. The porous body 60 is formed of, for example, resin or ceramic. The second signal line 61 is in contact with the soil through the porous body 60. Figure 3 As shown, the porous body 60 is a shape in which the surface 60a and the surface 60b facing each other in the thickness direction of the base 4 protrude from the base 4. The surface 60a on one side in the thickness direction is located at a position protruding from the surface 4a on one side of the base 4. The surface 60b on the other side in the thickness direction is located at a position protruding from the surface 4b on the other side of the base 4.

[0051] The first signal line 51 and the second signal line 61 are formed by containing a metal such as gold or copper. The first signal line 51 and the second signal line 61 are in a ring shape provided along the periphery of the base portion 4. The first signal line 51 and the second signal line 61 are provided in pairs. The shapes and numbers of the first signal line 51 and the second signal line 61 are not limited to the above-mentioned structure. The first signal line 51 and the housing portion 2 are electrically connected by a conductive line. The second signal line 61 and the housing portion 2 are connected by a conductive line.

[0052] Preferably, the surface shape of the porous body 60 exposed to the soil is a polygon with a quadrilateral or larger shape. Figure 4 As shown, the surface shape of the porous body 60 exposed to the soil is circular or cylindrical. In the case of a cylindrical shape, the porous body 60 has an outer peripheral surface protruding from the outer peripheral surface of the base 4. The porous body 60 with such a surface shape helps to improve the adhesion with the soil and can smoothly attract the moisture of the soil to the ceramic, and can detect the appropriate water potential WP.

[0053] It is preferable that the porous body 60 has a pore distribution suitable for soil used for growing vegetables, etc. The porous body 60 having a pore distribution suitable for the soil contributes to the high-precision measurement of the water potential WP of the soil. Therefore, regarding the pore distribution formed in the porous body 60, pores of various sizes are distributed in uniform numbers according to the pores included in 0.1 to 100 μm.

[0054] The surface 4a and the surface 4b of the base portion 4 are formed with concavoconvexities with a depth ranging from 0.1 to 500 μm. The concavoconvexities with a depth close to 0.1 μm help to improve the adhesion between clay soil and the printed circuit board. The concavoconvexities with a depth close to 500 μm help to improve the adhesion between sandy soil and the printed circuit board. The base portion 4 having such concavoconvexities with such a depth helps to improve the adhesion between the soil and the printed circuit board, and can provide appropriate detection of the sensor signal.

[0055] like Figure 1 As shown in FIG. 1 , the soil sensor 30 includes a processing unit 31 including a TDT measuring unit 311 and a capacitance measuring unit 312 and functions as a CPU, and a communication unit 32. The communication unit 32 outputs the processing result of the processing unit 31 to the acquisition unit 11 of the control device 100. The soil sensor 30 may also be a structure including a CPU and a measuring device that function as the TDT measuring unit 311 and the capacitance measuring unit 312 by calculation using a program or the like. The processing unit 31 may perform detection using both the signal line on the surface 4a side on one side and the signal line on the surface 4b side on the other side, or may perform detection using only one of them.

[0056] The TDT measuring unit 311 is connected to the first signal line 51 through a conductive line. The TDT measuring unit 311 measures the dielectric constant of the soil using the first signal line 51 that transmits high-frequency electromagnetic waves. The TDT measuring unit 311 measures the relative dielectric constant of the soil by measuring the transmission time of the electromagnetic wave in the signal line using a TDT method (Time Domain Transmission) called a time domain penetration method. The TDT measuring unit 311 calculates the volumetric water content VWC using a correlation curve that determines the relationship between the volumetric water content VWC of the soil and the dielectric constant or the relative dielectric constant. The correlation curve is a prescribed characteristic curve pre-stored in a storage unit or the like according to the soil quality of the soil. The soil sensor 30 transmits the volumetric water content VWC to the control device 100 via the communication unit 32. For example, the control device 100 controls the irrigation time and irrigation amount according to the volumetric water content VWC of the soil.

[0057] The processing unit 31 detects the electrical conductivity EC of the soil based on the rising slope or amplitude of the waveform of the transmission signal transmitted by the high-frequency electromagnetic wave in the first signal line 51. The soil sensor 30 transmits the detected electrical conductivity EC to the control device 100 via the communication unit 32. For example, the control device 100 estimates the amount of fertilizer in the soil based on the electrical conductivity EC for irrigation control.

[0058] The electrostatic capacitance measuring unit 312 is connected to the second signal line 61 through a conductive line. The electrostatic capacitance measuring unit 312 uses the low-frequency electromagnetic wave transmitted in the second signal line 61 to measure the electrostatic capacitance of the porous body 60. Due to the adsorption of water and capillary force, the water potential WP of the soil and the water potential WP of the porous body 60 are equivalent. The electrostatic capacitance measuring unit 312 uses this equivalent relationship to measure the water potential WP of the soil using the electrostatic capacitance of the porous body 60. If the water potential WP of the soil is small, water is strongly retained in the soil, so it is difficult for the plant to absorb water from the soil. The soil sensor 30 sends the measured water potential WP to the control device 100 via the communication unit 32. For example, the control device 100 controls the irrigation time and irrigation amount according to the water potential WP of the soil.

[0059] In addition, the control device 100 can also control the irrigation amount of water or culture solution according to the pF value of the soil so that the soil has an appropriate pF value for the cultivated crops. The control device 100 can also periodically measure the pF value of the soil through a timer and control the irrigation amount of water or culture solution according to the measured pF value of the soil.

[0060] The soil sensor 30 of the first embodiment includes a first signal line 51 that transmits high-frequency electromagnetic waves and faces the soil, and a porous body 60 having water permeability and water retention. The soil sensor 30 includes a second signal line 61 that transmits low-frequency electromagnetic waves having a frequency lower than the high frequency and faces the soil through the porous body, and a ground line arranged inside the first signal line 51. The second signal line 61 is arranged inside the first signal line 51 and the ground line.

[0061] In the soil sensor 30, a second signal line 61 for transmitting a relatively low-frequency electromagnetic wave is arranged inside the first signal line 51 for transmitting a high-frequency electromagnetic wave. Furthermore, by arranging a ground line between the first signal line 51 and the second signal line 61, the influence of the electric field of the high-frequency electromagnetic wave on the second signal line 61 can be suppressed. In addition, the influence of the electric field of the low-frequency electromagnetic wave on the first signal line 51 can also be suppressed. Through this technology, the soil sensor 30 achieves a reduction in the error of detecting the soil moisture content.

[0062] The processing unit 31 measures the volumetric moisture content of the soil using the transmission signal transmitted by the high-frequency electromagnetic wave in the first signal line, and measures the water potential of the soil using the low-frequency electromagnetic wave transmitted in the second signal line. Thus, the mutual influence between the electric field generated by one signal line and the electric field generated by the other signal line can be suppressed, so that a sensor that can measure both the volumetric moisture content and the water potential can be provided.

[0063] The processing unit 31 further measures the electrical conductivity of the soil based on the waveform of the transmission signal transmitted by the high-frequency electromagnetic wave through the first signal line. Thus, a sensor capable of appropriately measuring the volumetric water content, the water potential, and the electrical conductivity can be provided.

[0064] Second Embodiment

[0065] Reference Figure 5-6 The second embodiment is described. The second embodiment differs from the first embodiment in the structure of the base and the porous body of the soil sensor 130. The structure, function, and effect not specifically described in the second embodiment are the same as those in the above embodiment, and the differences are described below.

[0066] Figure 5 The soil sensor 130 shown in the figure includes a detection unit 101 and a housing 102. The detection unit 101 is cylindrical and buried in the soil of the field. The housing 102 is buried in the soil, or is not buried in the soil but is arranged outside the soil. The detection unit 101 includes a first detection unit 5 and a second detection unit 6. The second detection unit 106 includes a second signal line 61, a ground line 62, and a porous body 160. The detection unit 101 includes a first signal line 51, a second signal line 61, a porous body 160, and a base 104.

[0067] The porous body 160 is a portion corresponding to the porous body 60 of the first embodiment. Preferably, the base 104 is formed of, for example, a water-impermeable material, and water does not penetrate into the base 104. At least the surface of the base 104 is an insulator so that there is no short circuit between the first signal lines 51, between the second signal lines 61, and between the first signal line 51 and the second signal line 61. The base 104 is formed of the same material and surface treatment as the base 4 of the first embodiment. The base 104 has the longitudinal direction LD as the axial direction of the columnar body.

[0068] like Figure 6 As shown in FIG. 1 , a first signal line 51 and a ground line 52 are provided on the circumference of the front end side portion 104f of the base portion 104. A first signal line 51 and a ground line 52 are provided on the circumference of the root side portion 104r of the base portion 104. According to this structure, the soil sensor 130 can detect the volume water content VWC and the conductivity at two locations separated in the axial direction of the detection portion 101.

[0069] The front end side portion 104f and the root side portion 104r are formed to have the same outer diameter. The first signal line 51 formed on the front end side portion 104f and the first signal line 51 formed on the root side portion 104r are at the same radial position in the base portion 104. The first signal line 51 of the front end side portion 104f and the first signal line 51 of the root side portion 104r are in direct contact with the soil. The ground line 52 is provided on the front end side portion 104f or the root side portion 104r at a position closer to the porous body 160 than the first signal line 51. The ground line 52 is provided along the first signal line 51 at a position closer to the porous body 160 than the first signal line 51, with a certain interval relative to the first signal line 51.

[0070] like Figure 5 , Figure 6 As shown, the second signal line 61 and the ground line 62 are provided on the surface of the middle part 104m in the base part 104. The middle part 104m is a columnar body with a smaller outer diameter than the front end side part 104f and the root side part 104r. The porous body 160 has an outer peripheral surface coplanar with the outer peripheral surface 104a of the base part 104, and covers the second signal line 61 and the ground line 62. The porous body 160 can also be a structure having an outer peripheral surface protruding from the outer peripheral surface 104a of the base part 104. The ground line 62 is respectively provided at a position close to the front end side part 104f and a position close to the root side part 104r relative to the second signal line 61.

[0071] The second signal line 61 is located radially inside with respect to the first signal line 51. The second signal line 61 constitutes a ring-shaped line separated in the axial direction with respect to the first signal line 51 and having a smaller diameter. The second signal line 61 is surrounded on the radially outer side RD by the first signal line 51 of the front end side portion 104f separated in the axial direction. The second signal line 61 is surrounded on the radially outer side RD by the ground line 52 of the front end side portion 104f separated in the axial direction. The second signal line 61 is surrounded at the radially outer side RD by the first signal line 51 of the root side portion 104r separated in the axial direction. The second signal line 61 is surrounded at the radially outer side RD by the ground line 52 of the root side portion 104r separated in the axial direction.

[0072] The second signal line 61 and the ground line 62 are covered by a porous body 160 having a large number of pores. The porous body 160 is a cylindrical body formed of a material having water permeability and water retention. The porous body 160 is formed of, for example, ceramic. The second signal line 61 faces the soil through the porous body 160.

[0073] The first signal line 51 and the second signal line 61 are formed of a material containing a metal such as gold or copper. The first signal line 51 and the second signal line 61 are in a ring shape provided on the peripheral surface of the base portion 4. The first signal line 51 and the second signal line 61 are provided in pairs. The shapes and numbers of the first signal line 51 and the second signal line 61 are not limited to the above-mentioned structures. The first signal line 51 and the housing portion 2 are electrically connected by a conductive line. The second signal line 61 and the housing portion 2 are connected by a conductive line.

[0074] Preferably, the porous body 160 has a pore distribution suitable for soil used for growing vegetables, etc. The porous body 160 having a pore distribution suitable for the soil contributes to the high-precision measurement of the water potential WP of the soil. Therefore, regarding the pore distribution formed in the porous body 160, pores of various sizes are distributed in a uniform number according to the pores included in 0.1 to 100 μm.

[0075] The outer peripheral surface 104a of the base portion 4 is formed with concavo-convex portions having a depth of 0.1 to 500 μm. Concavo-convex portions having a depth of approximately 0.1 μm help improve the adhesion between clayey soil and the printed circuit board. Concavo-convex portions having a depth of approximately 500 μm help improve the adhesion between sandy soil and the printed circuit board. The base portion 410 having such concavo-convex portions of depth helps improve the adhesion between the soil and the printed circuit board, and can provide detection of appropriate sensing signals.

[0076] Third Embodiment

[0077] Reference Figure 7The third embodiment is described. The soil sensor of the third embodiment is different from the above embodiment in the structure related to the surface of the base portion. The structure, function, and effect not particularly described in the third embodiment are the same as those of the above embodiment, and the differences are described below.

[0078] like Figure 7 As shown, the soil sensor of the third embodiment includes a plurality of protrusions 4c protruding from the surface of the base 4, 104. The plurality of protrusions 4c protrude from at least one of the surface 4a on one side and the surface 4b on the other side of the base 4, 104. The plurality of protrusions 4c are formed by solidifying the molten resin dropped on the surface 4a on one side and the surface 4b on the other side.

[0079] According to the soil sensor of the third embodiment, the plurality of protrusions 4c contribute to improving the retention of the soil sensor with respect to the soil and the installation workability of the soil sensor.

[0080] Fourth Embodiment

[0081] Reference Figure 8 The fourth embodiment is described. The fourth embodiment differs from the second embodiment in the structure of the soil sensor 230 related to the first detection unit. The structure, function, and effect not particularly described in the fourth embodiment are the same as those in the above embodiment, and the differences are described below.

[0082] like Figure 8 As shown, the soil sensor 230 has a larger number of annular first signal lines 51 than the second embodiment. The detection unit 101 of the soil sensor 230 includes the first signal line 51, the second signal line 61, the porous body 160 and the base 104. The base 104 is a portion corresponding to the base 4 of the first embodiment. The second detection unit 106 includes the second signal line 61, the ground line 62 and the porous body 160.

[0083] The base portion 104 is provided with a plurality of annular first signal lines 51 and a plurality of annular ground lines 52. The first signal lines 51 are arranged at a plurality of separated locations in the base portion 104. The front end side portion 4f of the base portion 4 is provided with a plurality of first signal lines 51 separated and arranged in the axial direction and the length direction LD. The front end side portion 4f is provided with a plurality of ground lines 52 separated and arranged in the axial direction and the length direction LD. A ground line 52 is provided between two first signal lines 51 separated at the front end side portion 4f. The front end side portion 4f is provided with a temperature sensor 17 for detecting the temperature of the soil. According to this structure, a soil sensor 230 having a temperature sensor, a water potential detection portion, and a TDT detection portion at a plurality of locations can be provided. The soil sensor 230 can realize miniaturization of the device and simultaneous detection of a plurality of methods by integrating the detection functions of a plurality of methods into a structure.

[0084] Fifth Embodiment

[0085] Reference Figures 9 to 14 The fifth embodiment is described. The fifth embodiment differs from the above embodiment in the shape and structure of the base and porous body of the soil sensor. The structure, function, and effect not specifically described in the fifth embodiment are the same as those in the above embodiment, and the differences are described below.

[0086] The soil sensor of the fifth embodiment is as follows Figures 9 to 13 As shown, the structure forming the porous body portion and the base portion or the structure forming the first detection portion and the second detection portion is a regular polyhedron. Figures 9 to 14 The porous body and the base are formed of the same materials as those in the first embodiment.

[0087] Fig. 9 A first example of the soil sensor according to the fifth embodiment is shown. Fig. 9 The detection part 201 of the soil sensor shown is formed in a regular tetrahedron shape. The detection part 201 includes a base part 204 and a porous body part 260. In the base part 204, the first signal line 51 and the ground line 62 are arranged along the surface in a large surface area. The porous body part 260 has a surface that is coplanar with the surface of the base part 204 or protrudes from the surface of the base part 204, and covers the second signal line 61. The second signal line 61 is arranged inside the detection part 201 more than the first signal line 51 and the ground line 62. According to Fig. 9 The soil sensor shown has a symmetrical shape, so external stress can be easily applied evenly, ensuring strength and being less prone to damage.

[0088] Fig.10 A second example of the soil sensor according to the fifth embodiment is shown. Fig.10 In the soil sensor shown, the detection part 301 is formed in a regular hexahedron. The detection part 301 includes a base part 304 and a porous body part 360. In the base part 304, the first signal line 51 and the ground line 62 are arranged along the surface in a large surface area. The porous body part 360 has a surface that is coplanar with the surface of the base part 304 or protrudes from the surface of the base part 304, and covers the second signal line 61. The second signal line 61 is arranged inside the detection part 301 more than the first signal line 51 and the ground line 62. According to Fig.10 The soil sensor shown has a symmetrical shape, so external stress can be easily applied evenly, ensuring strength and being less prone to damage.

[0089] Fig.11 A third example of the soil sensor according to the fifth embodiment is shown. Fig.11In the soil sensor shown, the detection part 401 is formed in a regular octahedron shape. The detection part 401 includes a base part 404 and a porous body part 460. In the base part 404, the first signal line 51 and the ground line 62 are arranged along the surface in a large surface area. The porous body part 460 has a surface that is coplanar with the surface of the base part 404 or protrudes from the surface of the base part 404, and covers the second signal line 61. The second signal line 61 is arranged inside the detection part 401 more than the first signal line 51 and the ground line 62. According to Fig.11 The soil sensor shown has a symmetrical shape, so external stress can be easily applied evenly, ensuring strength and being less prone to damage.

[0090] Fig.12 A fourth example of the soil sensor according to the fifth embodiment is shown. Fig.12 In the soil sensor shown, the detection part 501 is formed in a regular dodecahedron shape. The detection part 501 includes a base part 504 and a porous body part 560. In the base part 504, the first signal line 51 and the ground line 62 are arranged along the surface in a large surface area. The porous body part 560 has a surface that is coplanar with the surface of the base part 504 or protrudes from the surface of the base part 504, and covers the second signal line 61. The second signal line 61 is arranged inside the detection part 501 more than the first signal line 51 and the ground line 62. According to Fig.12 The soil sensor shown has a symmetrical shape, so external stress can be easily applied evenly, ensuring strength and being less prone to damage.

[0091] Fig.13 A fifth example of the soil sensor according to the fifth embodiment is shown. Fig.13 In the soil sensor shown, the detection part 601 is formed in a regular icosahedron shape. The detection part 601 includes a base part 604 and a porous body part 660. In the base part 604, the first signal line 51 and the ground line 62 are arranged along the surface in a large surface area. The porous body part 660 has a surface that is coplanar with the surface of the base part 604 or protrudes from the surface of the base part 604, and covers the second signal line 61. The second signal line 61 is arranged inside the detection part 601 more than the first signal line 51 and the ground line 62. According to Fig.13 The soil sensor shown has a symmetrical shape, so external stress can be easily applied evenly, ensuring strength and being less prone to damage. Fig.14 The sixth example of the soil sensor according to the fifth embodiment is shown. Fig.14As shown, the soil sensor may also be a structure in which the detection part 701 is formed into a spherical shape. In the base part 704, the first signal line 51 and the ground line 62 are arranged along the surface in a larger surface area. The porous body 760 has a surface that is coplanar with the surface of the base part 704 or protrudes from the surface of the base part 704, and covers the second signal line 61. The second signal line 61 is arranged inside the detection part 701 more than the first signal line 51 and the ground line 62. Fig.14 The soil sensor shown has a symmetrical shape, so external stress can be applied evenly, ensuring strength and preventing damage.

[0092] Sixth Embodiment

[0093] Reference Fig.15 The sixth embodiment will be described. The soil sensor of the sixth embodiment differs from the above-described embodiment in the support structure of the base 4 with respect to the housing 2. The structure, function, and effect not particularly described in the sixth embodiment are the same as those of the above-described embodiment, and the differences will be described below.

[0094] The soil sensor of the sixth embodiment is as follows Fig.15 As shown, a sealing support portion 25 is provided to support the base portion 4 inserted into the interior of the housing portion 2 and to function as a sealing structure. The base portion 4 is inserted into the opening portion 2c of the housing portion 2, and has a portion located inside the housing portion 2 and a portion protruding outside the housing portion 2. The gap between the base portion 4 and the opening portion 2c of the housing portion 2 is sealed by a sealing portion 24 such as a packing.

[0095] The housing 2 also has an inner housing 2ic inside. That is, the housing 2 has a double structure with the housing 2 as an outer housing by having the inner housing 2ic built in. The inner housing 2ic accommodates a substrate 21 including a circuit portion. The substrate 21 is electrically connected to a pattern substrate of the base 4 or the like by a cable. The base 4 is inserted into the opening of the inner housing 2ic, and the gap between the base 4 and the opening 2c of the housing 2 is sealed by a sealing portion such as a filler. The sealing portion and the sealing portion 24 have the function of supporting the base 4. The interior of the inner housing 2ic is filled with a potting portion 22 such as a polyurethane resin. An absorbent 23 formed of a water-absorbent resin material is filled between the housing 2 and the inner housing 2ic. The absorbent 23 can be formed of, for example, polyacrylate. Even if water is immersed in the interior of the housing 2, the absorbent 23 suppresses water from entering the circuit portion and helps to improve the waterproofness of the circuit.

[0096] The sealing support portion 25 is formed in a fillet shape by being in close contact with the partial surface of the base portion 4 protruding from the shell portion 2 to the outside and the surface of the shell portion 2 on the outside of the shell portion 2. The sealing support portion 25 is formed of a material having elasticity that can be deformed by the action of an external force. The sealing support portion 25 is preferably formed of a polyurethane resin having high viscosity. The sealing support portion 25 can improve the close contact between the surface of the base portion 4 and the opening portion 2c of the shell portion 2 by high viscosity. In this way, the sealing support portion 25 provides the function of supporting the base portion 4 relative to the shell portion 2 and the function of suppressing water intrusion into the shell portion 2.

[0097] Seventh Embodiment

[0098] Reference Fig.16 The seventh embodiment is described. The soil sensor of the seventh embodiment differs from the above-mentioned embodiment in the support structure related to the porous body and the base. The structure, function, and effect not particularly described in the seventh embodiment are the same as those of the above-mentioned embodiment, and the differences are described below.

[0099] The soil sensor of the seventh embodiment is as follows Fig.16 As shown, it has a structure that clamps the porous body 60, the base 4 and the outer support 7. The outer support 7 is a plate-shaped portion facing the soil, and is formed of, for example, a stainless steel material. The shaft 80a of the screw 80 passes through the stacked body in which the outer support 7, the porous body 60, the base 4, the porous body 60 and the outer support 7 are stacked in sequence. This clamping structure constrains the base 4, the porous bodies 60 arranged on both sides of the base 4, and the outer support 7 arranged on the outside of each porous body 60 by the screw 80 and the nut 81. The screw 80 and the nut 81 are an example of a constraining member for constraining the stacked body to compress it.

[0100] The surface of the outer support portion 7 has such a flatness that a gap exceeding 2 mm does not occur between the outer support portion 7 and the porous body 60. With this structure, it is possible to suppress the intrusion of soil particles between the outer support portion 7 and the porous body 60 when the laminate is provided inside the soil. Thus, it is possible to avoid the intrusion of cracks into the porous body 60.

[0101] Eighth Embodiment

[0102] Reference Figure 17-18 The eighth embodiment is described. The soil sensor of the eighth embodiment is different from the above-described embodiment in the structure related to the surface of the base portion. The structure, function, and effect not particularly described in the eighth embodiment are the same as those of the above-described embodiment, and the differences are described below.

[0103] like Fig.17As shown in the first example of the eighth embodiment, the soil sensor of the eighth embodiment includes a base portion 4 having a plurality of layers. The base portion 4 of the eighth embodiment includes a plurality of signal layers 41 provided with a first signal line 51 and a ground line 52, and a surface layer 42 stacked on the outside of each signal layer 41. The surface layer 42 is provided so as to form two surfaces in the thickness direction TD of the base portion 4, respectively. The surface layer 42 is formed of a resin. At least a portion of the signal layer 41 is insulated to avoid a short circuit between the first signal line 51 and the first signal line 51. For example, when the thickness of the base portion 4 is 1.6 mm, the thickness of the surface layer 42 is set to a value included in 200 to 400 μm. According to the first example, it is possible to suppress the situation where the pattern formed on the base portion 4 contacts the soil and is damaged, and it is possible to provide a soil sensor with high robustness to the soil.

[0104] like Fig.18 As shown in the second example of the eighth embodiment, the soil sensor of the eighth embodiment includes a surface layer 142 composed of a plurality of layers stacked on the surface of the base portion 4. The surface layer 142 includes an outermost resin layer 142a, a glass layer 142b located inside the resin layer 142a, and a ceramic layer 142c located inside the glass layer 142b. The resin layer 142a is formed of a polymer resin and has a thickness of, for example, about 10 μm. The glass layer 142b is a layer having a higher hardness than the resin layer 142a and is formed to have a thickness included in 0.1 to 0.3 μm. The ceramic layer 142c is a porous layer.

[0105] The surface layer 142 includes a plurality of layers stacked from the outside to the inside, and has a glass layer 142b or a ceramic layer 142c on the inside of the outermost resin layer 142a. According to this structure, the glass layer 142b and the like can prevent the pattern formed on the inside from being damaged by contact with the soil, and a soil sensor with high robustness to the soil can be provided.

[0106] Ninth Embodiment

[0107] Reference Fig.19 The ninth embodiment is described. The soil sensor of the ninth embodiment is different from the above embodiment in the abnormality determination process of the soil sensor. The structure, function, and effect not particularly described in the ninth embodiment are the same as those of the above embodiment, and the differences are described below.

[0108] Utilization of soil sensor in the ninth embodiment Fig.19 The abnormality determination process is performed based on the characteristic curve of the soil volumetric water content VWC and the water potential WP shown. Fig.19 This is an abnormality determination curve in which the volumetric water content VWC of the soil is set on the horizontal axis and the water potential WP is set on the vertical axis. Fig.19The curve 1ab is a boundary line indicating an abnormal state in which the soil contains a large amount of water but the porous body fails to absorb the water, and the close contact between the sensor and the soil is poor. Fig.19 The curve 2ab is a boundary line indicating an abnormal state in which the soil is dry in a state where water accumulates in the gap between the porous body and the soil and the soil is soaked. The abnormality determination curve is a predetermined characteristic curve pre-stored in a storage unit of the soil sensor or the like.

[0109] The processing unit 31 determines that the measured volumetric water content VWC and water potential WP are between the curves 1ab and 2ab as a normal state. The processing unit 31 determines that the measured VWC and WP are not between the curves 1ab and 2ab as an abnormal state.

[0110] In the VWC sensor using the high-frequency electric field radiated into the soil, the VWC of the entire area where the electric field extends is measured. Therefore, even if the close contact between the sensor and the soil deteriorates, the measured value does not change significantly. On the other hand, the measured value of the WP sensor is greatly affected by whether the close contact with the soil is good or not. If the measured values ​​of these two sensors are combined to draw the water retention curve of the soil, when the close contact is poor, it becomes a point that deviates from the normal state, so it is possible to distinguish between dry soil. Therefore, by making a judgment using the above-mentioned curves 1ab and 2ab, it is possible to realize an abnormal judgment that distinguishes between poor close contact between the sensor and the soil and dry soil.

[0111] The processing unit 31 uses two abnormality determination curves representing the measured volumetric moisture content and water potential and the stored relationship between the volumetric moisture content and water potential to determine whether it is an abnormal state. In this way, poor contact between the sensor and the soil and dry soil can be classified. Therefore, it is possible to avoid mistaking the poor contact state for dry soil and excessive irrigation, which helps to correct the setting state of the sensor.

[0112] Tenth Embodiment

[0113] Reference Fig. 20 The tenth embodiment is described. The soil sensor of the tenth embodiment is different from the above-mentioned embodiment in that an abnormality determination process is performed based on the comparison of the measured values ​​of two locations. The structure, function, and effect not specifically described in the tenth embodiment are the same as those of the above-mentioned embodiment, and the differences are described below.

[0114] like Fig. 20As shown, the TDT measuring unit 311 of the tenth embodiment includes a first measuring unit 311a and a second measuring unit 311b. The first measuring unit 311a performs measurement using a signal line arranged at a first position of the detection unit. The second measuring unit 311b performs measurement using a signal line arranged at a second position of the detection unit.

[0115] The capacitance measuring unit 312 of the tenth embodiment includes a first measuring unit 312a and a second measuring unit 312b. The first measuring unit 312a performs measurement using a signal line arranged at a first position of the detection unit. The second measuring unit 311b performs measurement using a signal line arranged at a second position different from the first position. The processing unit 31 determines whether the measured value is abnormal based on the result of comparing the value measured at the first position with the value measured at the third position. For example, Fig.21 As shown, the processing unit 31 generates each processing waveform using two measured values, and determines whether it is abnormal by analyzing the difference between the two output values. As an example of the first position, it is a signal line arranged on the surface side of one side in the thickness direction TD in the detection unit 1. As an example of the second position, it is a signal line arranged on the back side of the other side in the thickness direction TD in the detection unit 1. In this example, the processing unit 31 determines whether the measured value is abnormal based on the result of comparing the values ​​independently measured on the two sides of the detection unit.

[0116] In the processing unit 31, as a comparison of the measured values ​​of the above-mentioned two parts, the difference in the measured values, the difference in the shape, width, cycle time, etc. of the measured waveform is used to determine the degree of deviation of the difference from the reference. This determination is performed in consideration of the detection accuracy and processing accuracy. In the comparison of the measured values ​​of the two parts in the processing unit 31, it is determined that there is an abnormality in the case of the following example.

[0117] An abnormality is determined when the displacement of the measured values ​​of two locations is too different. An abnormality is determined when the measured value of one location is fixed. An abnormality is determined when the measured value of one location is positive and the measured value of the other location is negative. An abnormality is determined when the difference in the measured waveforms of the two locations is not within the assumed phase range or variation range. An abnormality is determined when the measured values ​​of the two locations at the time of the self-inspection deviate from the assumed values.

[0118] The processing unit 31 of the tenth embodiment determines whether an abnormal state exists based on the result of comparing the measured values ​​of two locations at different positions. As a result, it is possible to find damage caused by the soil and the probability of disconnection increases, and stable application is achieved with an appropriate output value, which helps to improve the stability of the irrigation system using the soil sensor. Furthermore, it is possible to detect failures caused by self-heating and temperature changes, and it is possible to facilitate the failure analysis of the soil sensor.

[0119] <Other embodiments>

[0120] The disclosure of this specification is not limited to the illustrated embodiments. The disclosure includes the illustrated embodiments and the variations made by those skilled in the art based on them. For example, the disclosure is not limited to the combination of components and elements shown in the embodiments, and can be implemented with various variations. The disclosure can be implemented through a variety of combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure includes the case where components and elements of the embodiments are omitted. The disclosure includes the replacement or combination of components and elements between one embodiment and other embodiments. The disclosed technical scope is not limited to the description of the embodiments. The disclosed technical scope is represented by the description of the claims, and it should be understood that it also includes all changes in the meaning and scope equivalent to the description of the claims.

[0121] The apparatus and methods described in the present disclosure may be implemented by a dedicated computer having a processor programmed to execute one or more functions embodied by a computer program. Alternatively, the apparatus and methods described in the present disclosure may be implemented by a dedicated hardware logic circuit. Alternatively, the apparatus and methods described in the present disclosure may be implemented by one or more dedicated computers consisting of a combination of a processor that executes a computer program and one or more hardware logic circuits. In addition, the computer program may be stored in a non-removable tangible recording medium that is readable by a computer as instructions executed by the computer.

[0122] Disclosure of technical ideas

[0123] This specification discloses multiple technical concepts described in the following multiple items. Some items are described by selectively citing multiple dependent forms of previous items in subsequent items. The items described in these multiple dependent forms define multiple technical concepts.

[0124] Technical Thought 1

[0125] A soil sensor comprises: a first signal line (51) transmitting high-frequency electromagnetic waves and facing the soil; a porous body (60) having water permeability and water retention; a second signal line (61) transmitting low-frequency electromagnetic waves having a frequency lower than the high frequency, facing the soil across the porous body; and a ground line (52, 62) arranged on the inner side of the first signal line; the second signal line is arranged on the inner side of the first signal line and the ground line.

[0126] Technical Thought 2

[0127] As described in the soil sensor of the technical idea 1, the frequency of the electromagnetic wave transmitted through the first signal line is set to a frequency band that is 100 times or more higher than the frequency of the electromagnetic wave transmitted through the second signal line.

[0128] Technical Thought 3

[0129] The soil sensor as described in Technical Idea 1 or Technical Idea 2 comprises a processing unit (31) which measures the volumetric moisture content of the soil using a transmission signal transmitted by a high-frequency electromagnetic wave in the above-mentioned first signal line, and measures the water potential of the soil using a low-frequency electromagnetic wave transmitted in the above-mentioned second signal line.

[0130] Technical Thought 4

[0131] In the soil sensor described in technical idea 3, the processing unit further measures the electrical conductivity of the soil based on the waveform of the transmission signal transmitted by the high-frequency electromagnetic wave through the first signal line.

[0132] Technical Thought 5

[0133] In the soil sensor according to any one of technical concepts 1 to 4, the surface of the porous body exposed to the soil has a shape of a polygon larger than a quadrilateral.

[0134] Technical Thought 6

[0135] The soil sensor as described in any one of technical ideas 1 to 5 comprises a base portion (4; 104) provided with the first signal line and the ground line, and a surface of the base portion is provided with depressions and projections with a depth in the range of 0.1 to 500 μm.

[0136] Technical Thought 7

[0137] The soil sensor as described in any one of technical ideas 1 to 5 comprises a base portion (4; 104) provided with the first signal line and the ground line, and a plurality of protrusions (4c) are provided on the surface of the base portion.

[0138] Technical Thought 8

[0139] The soil sensor as described in any one of technical ideas 1 to 5 comprises a base portion (104) provided with the first signal line and the ground line, wherein the first signal line is arranged at a plurality of separated locations in the base portion.

[0140] Technical Thought 9

[0141] The soil sensor as described in any one of technical ideas 1 to 4 comprises a base portion (104) provided with the first signal line and the ground line, wherein the base portion and the porous body portion are integrally formed into a regular polyhedron.

[0142] Technical Thought 10

[0143] A soil sensor as described in any one of Technical Ideas 1 to 7 comprises: a base portion (4) provided with the first signal line and the ground line; and a shell portion (2) having a built-in circuit portion electrically connected to the first signal line and the second signal line, and having a part of the base portion built-in; and a sealing support portion (25) supporting the base portion on the outside of the shell portion, being in close contact with a portion of the surface of the base portion protruding from the shell portion to the outside and a surface of the shell portion, and being formed into a rounded shape.

[0144] Technical Thought 11

[0145] A soil sensor as described in any one of Technical Ideas 1 to 4 comprises: a base portion (4) provided with the first signal line and the ground line; and a stacked body, in which an outer support portion (7), the porous body portion and the base portion are stacked in sequence from the outside to the inside, and is constrained by a constraining member (80, 81); the surface of the outer support portion has a flatness such that a gap of no more than 2 mm is generated between the outer support portion and the porous body portion.

[0146] Technical Thought 12

[0147] A soil sensor as described in any one of technical ideas 1 to 5 comprises a base portion (4; 104) provided with the first signal line and the ground line; the base portion has a surface layer (42; 142) covering the first signal line and the ground line.

[0148] Technical Thought 13

[0149] As described in the soil sensor of technical idea 12, the surface layer includes a plurality of layers stacked from the outside to the inside, and has a glass layer or a ceramic layer on the inner side of the outermost resin layer.

[0150] Technical Thought 14

[0151] A soil sensor as described in any one of Technical Ideas 1 to 13 comprises a processing unit (31) for measuring the volume moisture content of the soil by using a transmission signal transmitted in the above-mentioned first signal line by a high-frequency electromagnetic wave and for measuring the water potential of the soil by using a low-frequency electromagnetic wave transmitted in the above-mentioned second signal line; the above-mentioned processing unit uses two abnormality judgment curves representing the relationship between the measured volume moisture content and the above-mentioned water potential and the stored volume moisture content and water potential to judge whether it is an abnormal state; the above-mentioned two abnormality judgment curves are a curve representing poor adhesion to the soil and a curve representing dryness of the soil.

[0152] Technical Thought 15

[0153] A soil sensor as described in any one of Technical Ideas 1 to 13 comprises a processing unit (31) for measuring the volumetric moisture content of the soil by using a transmission signal transmitted in the above-mentioned first signal line using a high-frequency electromagnetic wave, and for measuring the water potential of the soil by using a low-frequency electromagnetic wave transmitted in the above-mentioned second signal line; the above-mentioned processing unit determines whether it is an abnormal state based on the result of comparing the measured values ​​of two parts at different positions.

Claims

1. A soil sensor, characterized in that: have: A first signal line (51) transmits high-frequency electromagnetic waves and faces the soil; The porous body (60) has water permeability and water retention properties; A second signal line (61) transmits a low-frequency electromagnetic wave having a frequency lower than the high-frequency wave, and faces the soil through the porous body; as well as A ground line (52, 62) is arranged inside the first signal line; The second signal line is arranged inside the first signal line and the ground line.

2. The soil sensor according to claim 1, characterized in that: The frequency of the electromagnetic wave transmitted through the first signal line is set to a frequency band that is 100 times or more higher than the frequency of the electromagnetic wave transmitted through the second signal line.

3. The soil sensor according to claim 1 or 2, characterized in that: The invention also comprises a processing unit (31) for measuring the volumetric water content of the soil by using the transmission signal transmitted by the high-frequency electromagnetic wave in the first signal line, and for measuring the water potential of the soil by using the low-frequency electromagnetic wave transmitted in the second signal line.

4. The soil sensor according to claim 3, characterized in that: The processing unit further measures the electrical conductivity of the soil based on the waveform of the transmission signal transmitted by the high-frequency electromagnetic wave through the first signal line.

5. The soil sensor according to claim 1, characterized in that: The surface of the porous body exposed to the soil has a shape of a polygon of a quadrilateral or larger shape.

6. The soil sensor according to claim 1, characterized in that: A base portion (4; 104) provided with the first signal line and the ground line; The surface of the base portion has irregularities having a depth in the range of 0.1 to 500 μm.

7. The soil sensor according to claim 1, characterized in that: A base portion (4; 104) provided with the first signal line and the ground line; A plurality of protrusions (4c) are provided on the surface of the base portion.

8. The soil sensor according to claim 1, characterized in that: A base portion (104) is provided with the first signal line and the ground line; The first signal line is arranged at a plurality of separate locations in the base portion.

9. The soil sensor according to claim 1, characterized in that: A base portion (104) is provided with the first signal line and the ground line; The base portion and the porous body portion are integrally formed in a regular polyhedron shape.

10. The soil sensor according to claim 1, characterized in that: have: A base portion (4) is provided with the first signal line and the ground line; and A housing (2) having a circuit portion electrically connected to the first signal line and the second signal line, and having a part of the base portion built therein; A seal support portion (25) is also provided, which supports the base portion outside the shell portion and is in close contact with a partial surface of the base portion protruding from the shell portion to the outside and a surface of the shell portion, and is formed in a rounded shape.

11. The soil sensor according to claim 1, characterized in that: have: A base portion (4) is provided with the first signal line and the ground line; and The stacked body is stacked with the outer supporting part (7), the porous body part and the base part in order from the outside to the inside, and is constrained by the constraining parts (80, 81); The surface of the outer supporting portion has such flatness that a gap exceeding 2 mm does not occur between the outer supporting portion and the porous body.

12. The soil sensor according to claim 1, characterized in that: A base portion (4; 104) provided with the first signal line and the ground line; The base portion has a surface layer (42; 142) covering the first signal line and the ground line.

13. The soil sensor according to claim 12, characterized in that: The surface layer includes a plurality of layers stacked from the outside to the inside, and has a glass layer or a ceramic layer on the inner side of the outermost resin layer.

14. The soil sensor according to claim 1, characterized in that: A processing unit (31) is provided, which measures the volumetric moisture content of the soil using the transmission signal transmitted by the high-frequency electromagnetic wave in the first signal line, and measures the water potential of the soil using the low-frequency electromagnetic wave transmitted in the second signal line; The processing unit determines whether the abnormal state is present by using two abnormality determination curves indicating the measured volumetric water content and the water potential and the stored relationship between the volumetric water content and the water potential; The two abnormality determination curves are a curve indicating poor adhesion to the soil and a curve indicating dryness of the soil.

15. The soil sensor according to claim 1, characterized in that: A processing unit (31) is provided, which measures the volumetric moisture content of the soil using the transmission signal transmitted by the high-frequency electromagnetic wave in the first signal line, and measures the water potential of the soil using the low-frequency electromagnetic wave transmitted in the second signal line; The processing unit determines whether or not the state is abnormal based on the result of comparing the measured values ​​at two different locations.

Images