Sensor device and moisture content measuring device

Abstract

The sensor device includes a sensor head and a measurement unit. The sensor head includes a first probe and a second probe. The first probe includes a first transmission micro-antenna portion and a second transmission micro-antenna portion. The second probe is arranged at a predetermined distance from the first probe and includes a first reception micro-antenna portion and a second reception micro-antenna portion. The measurement unit generates a measurement signal including information on electromagnetic wave propagation characteristics in a medium between the first and second transmission micro-antenna portions and the first and second reception micro-antenna portions. The first probe and the second probe have different probe lengths from each other, or the distance between the first transmission micro-antenna portion and the first reception micro-antenna portion and the distance between the second transmission micro-antenna portion and the second reception micro-antenna portion are different from each other.

Description

TECHNICAL FIELD

[0001] The present technology relates to a sensor device and a water content measuring device for measuring water content in a medium such as soil. BACKGROUND

[0002] As a method for measuring water content in a medium, time domain reflectometry (TDR) is known. This method includes measuring a relative permittivity based on behavior of a high-frequency wave traveling back and forth between measurement probes. Specifically, this method includes transmitting an electromagnetic wave along a metal probe buried in a medium, and calculating water content in the medium from a relative permittivity measured based on a reflected response of the electromagnetic wave.

[0003] There is a problem in which, since TDR measures a relative permittivity using electromagnetic wave propagation characteristics in the vicinity of a probe in a medium, a gap generated in the vicinity of the probe has a great influence on measurement, and thus it is difficult to correctly measure the relative permittivity. In order to solve the above problem, a technology is disclosed which measures a relative permittivity of a medium between two probes each including a minute opening for an electromagnetic wave, respectively used as a transmission-side probe and a reception-side probe, at a distance from each other (see, for example, Patent Literature 1).

[0004] LIST OF CITATIONS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: WO2018 / 221051 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In this case, a gap generated in the vicinity of the probe is smaller than a distance between the probes, and thus has little influence on the measurement result. This makes it possible to calculate a relative permittivity (which is proportional to water content) with reduced error. When a plurality of minute openings are provided to each probe, this makes it possible to measure water content at a plurality of positions in the medium at the same time.

[0009] When a plurality of minute openings are provided to each probe, a plurality of propagation paths of electromagnetic waves are formed. On the other hand, it has been proven that, when a measurement distance between a certain minute opening provided to the transmission-side probe and a certain minute opening provided to the reception-side probe is equal to a measurement distance (total length of a signal transmission path) between another minute opening provided to the transmission-side probe and another minute opening provided to the reception-side probe, the paths inadvertently have equal propagation lengths. This results in generation of noise, and thus results in measurement error.

[0010] In view of the above, an object of the present technology is to provide a sensor device and a water content measuring device that make it possible to reduce measurement error and improve measurement accuracy of the relative permittivity of a medium or the water content in a medium.

[0011] Solution to problem

[0012] A sensor device according to an embodiment of the present technology includes a sensor head and a measurement unit.

[0013] The sensor head includes a first probe and a second probe. The first probe includes a first transmission micro-antenna portion and a second transmission micro-antenna portion. The second probe is arranged at a predetermined distance from the first probe and includes a second reception micro-antenna portion and a second reception micro-antenna portion.

[0014] The measurement unit includes a controller that generates a measurement signal including information on an electromagnetic wave propagation characteristic in a medium between the first transmission micro-antenna portion and the first reception micro-antenna portion and information on an electromagnetic wave propagation characteristic in a medium between the second transmission micro-antenna portion and the second reception micro-antenna portion.

[0015] A signal processing unit measures the water content in the medium on the basis of the measurement signal.

[0016] The first probe and the second probe have different probe lengths. Alternatively, a distance between the first transmission micro-antenna portion and the first reception micro-antenna portion and a distance between the second transmission micro-antenna portion and the second reception micro-antenna portion are different from each other.

[0017] The first probe and the second probe can each be constituted by a coaxial cable including a core portion and a shield portion, and the first transmission micro-antenna portion, the second transmission micro-antenna portion, the first reception micro-antenna portion, and the second reception micro-antenna portion each include an opening provided at a portion of the shield portion.

[0018] The second probe can have a bent portion provided between the first reception micro-antenna portion and the second reception micro-antenna portion.

[0019] The first probe can have a folded portion at which the first transmission micro-antenna portion is provided, and the second transmission micro-antenna portion is provided at a distal end of the first probe.

[0020] The sensor head can further have a support that supports the first probe and the second probe, and the first probe is supported by the support in a state of being non-parallel to the second probe.

[0021] The first probe can include a third transmitting micro-antenna portion, and the second probe can include a third receiving micro-antenna portion. The measurement unit generates a measurement signal further including information on an electromagnetic wave propagation characteristic in the medium between the third transmitting micro-antenna portion and the third receiving micro-antenna portion.

[0022] The sensor head can include a first signal transmission path passing between the first transmitting micro-antenna portion and the first receiving micro-antenna portion, or between the first transmitting micro-antenna portion and the second receiving micro-antenna portion, and a second signal transmission path passing between the second transmitting micro-antenna portion and the first receiving micro-antenna portion, or between the second transmitting micro-antenna portion and the second receiving micro-antenna portion. A path length difference between the first signal transmission paths, a path length difference between the second signal transmission paths, and a path length difference between the first signal transmission paths and the second signal transmission paths can each be greater than or equal to a predetermined effective wavelength.

[0023] The arrangement of the first and second transmitting micro-antenna portions and the arrangement of the first and second receiving micro-antenna portions can be asymmetric with respect to each other.

[0024] A water content measurement device according to an embodiment of the present technology includes a sensor head, a measurement unit, and a signal processing unit.

[0025] The sensor head has a first probe including a first transmitting micro-antenna portion and a second transmitting micro-antenna portion, and a second probe arranged at a predetermined distance from the first probe, the second probe including a first receiving micro-antenna portion and a second receiving micro-antenna portion.

[0026] The measurement unit has a controller that generates a measurement signal including information on an electromagnetic wave propagation characteristic in the medium between the first transmitting micro-antenna portion and the first receiving micro-antenna portion, and information on an electromagnetic wave propagation characteristic between the second transmitting micro-antenna portion and the second receiving micro-antenna portion.

[0027] The signal processing unit measures a water content in the medium based on the measurement signal.

[0028] The signal processing unit can include a delay time calculator that calculates an electromagnetic wave propagation delay time between the first probe and the second probe based on the measurement signal, a relative permittivity calculator that calculates a relative permittivity of the medium based on the propagation delay time, and a water content calculator that calculates a water content in the medium based on the relative permittivity. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1is a schematic configuration view illustrating a basic configuration of a moisture content measuring apparatus according to an embodiment of the present technology.

[0030] Figure 2 is a block diagram illustrating a configuration of a moisture content measuring apparatus.

[0031] Figure 3 is a block diagram illustrating a configuration of a measuring unit in a moisture content measuring apparatus.

[0032] Figure 4 is a flowchart of a moisture content measuring method according to an embodiment of the present technology.

[0033] Figure 5 is a schematic view illustrating a configuration of a sensor head according to Comparative Example 1.

[0034] Figure 6 is a view illustrating a mode of transmission of a signal in Figure 5 the sensor head according to Comparative Example 1.

[0035] Figure 7 is a graph illustrating results of test measurements performed by using the sensor head according to Comparative Example 1 to emit and receive electromagnetic waves of a predetermined frequency. Figure 5

[0036] Figure 8 is a schematic view illustrating a configuration of a sensor apparatus according to a first embodiment of the present technology.

[0037] Figure 9 is a view illustrating a mode of transmission of a signal in Figure 8 the sensor apparatus according to the first embodiment of the present technology.

[0038] Figure 10 is a graph illustrating results of test measurements performed by using the sensor apparatus according to the first embodiment of the present technology to emit and receive electromagnetic waves of a predetermined frequency. Figure 8

[0039] is a graph in which results of Figure 11 and Figure 7 are overlaid. Figure 10

[0040] is a schematic view illustrating a configuration of two arbitrary adjacent path modes with respect to a signal transmission path mode between probes of the present technology. Figure 12

[0041] is a schematic view illustrating a configuration of another two arbitrary adjacent path modes with respect to a signal transmission path mode between probes of the present technology. Figure 13

[0042] is a schematic view illustrating a configuration of a sensor apparatus according to a second embodiment of the present technology. Figure 14

[0043] is a schematic view illustrating a configuration of a sensor apparatus according to a second embodiment of the present technology.​Figure 15 A configuration of a sensor device according to a third embodiment of the present technology is schematically illustrated.

[0044] Figure 16 A configuration of a sensor device according to a fourth embodiment of the present technology is schematically illustrated.

[0045] Figure 17 A configuration of a sensor device according to a fifth embodiment of the present technology is schematically illustrated.

[0046] Figure 18 A configuration of a sensor head according to Comparative Example 2 is schematically illustrated.

[0047] Figure 19 A configuration of a sensor device according to a sixth embodiment of the present technology is schematically illustrated.

[0048] Figure 20 A configuration of a sensor device according to a seventh embodiment of the present technology is schematically illustrated.

[0049] Figure 21 A configuration of a sensor head according to Comparative Example 3 is schematically illustrated. DETAILED DESCRIPTION

[0050] Hereinafter, embodiments according to the present technology will be described with reference to the accompanying drawings.

[0051] [Basic Configuration]

[0052] First, a basic configuration of a moisture content measuring device according to the present embodiment will be described.

[0053] Figure 1 A configuration of a moisture content measuring device 100 is schematically illustrated. Figure 2 is a block diagram schematically illustrating a configuration of the moisture content measuring device 100.

[0054] [Moisture Content Measuring Device]

[0055] The moisture content measuring device 100 includes a sensor device 10 and a signal processing unit 50. Here, an example in which the present technology is applied to measure a moisture content in soil in which a crop is to be grown will be described.

[0056] The sensor device 10 acquires an electromagnetic wave propagation characteristic in a medium (soil) M, and generates a measurement signal S1 used to calculate a relative permittivity of the medium M. The signal processing unit 50 receives the measurement signal S1 from the sensor device 10, and calculates a moisture content in the medium M based on the measurement signal S1.

[0057] The sensor device 10 includes a sensor head 20 and a measurement unit 30.

[0058] (sensor head)

[0059] The sensor head 20 includes a transmitting probe 21 (first probe) and a receiving probe 22 (second probe). The sensor head 20 includes a micro antenna portion 210 and a micro antenna portion 220, which are arranged in a medium M such as soil and enable transmission and reception of electromagnetic waves EW of a specific frequency between the transmitting probe 21 and the receiving probe 22.

[0060] The transmitting probe 21 and the receiving probe 22 are buried in the medium M in a substantially vertical posture so that the transmitting probe 21 and the receiving probe 22 face each other at a distance D from each other. The transmitting probe 21 and the receiving probe 22 each include a coaxial cable including a core portion Cl and a shield portion C2. The thickness and length of the cable are not particularly limited, and the cable can have any thickness and any length. For example, when the cable has a thickness (diameter) of 2 mm to 6 mm, the cable can be easily inserted into soil.

[0061] The core portion Cl includes a copper wire, and the shield portion C2 includes a copper tube, but the shield portion C2 can include a mesh of copper wires. Although not illustrated, the outer surface of the shield portion C2 is covered with a protective layer made of an insulating material.

[0062] The transmitting probe 21 is connected to an output terminal 34 (see Figure 3 ) of the measurement unit 30 and transmits a transmission signal from the measurement unit 30 to the micro antenna portion 210. The micro antenna portion 210 is provided at or near the tip (end portion) 23 of the transmitting probe 21 and transmits electromagnetic waves EW corresponding to the transmission signal to the receiving probe 22.

[0063] The receiving probe 22 is connected to an input terminal 35 (see Figure 3 ) of the measurement unit 30, receives electromagnetic waves EW using the micro antenna portion 220, and inputs a reception signal to the measurement unit 30. The antenna portion 220 is provided at or near the tip (end portion) of the transmitting probe 22 so that the micro antenna portion 220 faces the micro antenna portion 210 of the transmitting probe 21. The antenna portions 210 and 220 are not limited to being provided on the tips of the probes 21 and 22, respectively, and can be provided at any positions, such as central positions of the probes 21 and 22, respectively.

[0064] The micro antenna portions 210 and 220 are used to locally transmit and receive electromagnetic waves EW at respective predetermined positions in the probes 21 and 22, and the micro antenna portions 210 and 220 are each generally formed small in size enough not to resonate the respective probes 21 and 22. This makes it possible to prevent a decrease in measurement accuracy due to resonance of the probes 21 and 22.

[0065] The micro antenna portion 210 and the micro antenna portion 220 each include an opening H (see FIG. 2) provided at a portion of the shield portion C2. In other words, the probe 21 and the probe 22 each include a leaky coaxial antenna, and the leaky coaxial antennas of the probe 21 and the probe 22 include the micro antenna portion 210 and the micro antenna portion 220, respectively, as a radio wave leakage portion. Figure 2 ). In other words, the probe 21 and the probe 22 each include a leaky coaxial antenna, and the leaky coaxial antennas of the probe 21 and the probe 22 include the micro antenna portion 210 and the micro antenna portion 220, respectively, as a radio wave leakage portion.

[0066] The opening H has an opening shape such as a rectangular shape, a circular shape, an elliptical shape, or an oval shape, and the opening H is generally formed to have an oval shape, and the oval shape of the opening H of the micro antenna portion 210 and the micro antenna portion 220 has a long axis in the longitudinal direction of the probe 21 and the probe 22, respectively. The long axis of the opening H can be appropriately set according to the wavelength of the electromagnetic wave EW to be used. For example, when the wavelength of the electromagnetic wave EW is 500 MHz to 8 GHz, the length of the long axis (Z axis) of the opening H is about 5 mm to about 15 mm.

[0067] The transmitting probe 21 and the receiving probe 22 can each include an end resistance at the tip end 23. The end resistance is electrically connected between the tip end of the core portion C1 and the shield portion C2. This prevents unwanted reflection of the transmission signal and the reception signal at the tip end of the probe.

[0068] Advantageously, the tip end 23 of the transmitting probe 21 and the receiving probe 22 is covered with an electromagnetic wave penetration protection member (not shown), and the electromagnetic wave penetration protection member (not shown) covers the micro antenna portion 210 and the micro antenna portion 220, respectively.

[0069] The transmitting probe 21 and the receiving probe 22 also each include a sheath 24 including an electromagnetic wave absorbing material. The sheath 24 covers the outer peripheral surface around the micro antenna portion 210 and the micro antenna portion 220 (opening H) of the probe 21 and the probe 22. The sheath 24 of the probe 21 and the probe 22 prevents the transmission signal and the reception signal from leaking from the area outside the opening H.

[0070] Ferrite is mainly used as the electromagnetic wave absorbing material included in the sheath 24. Without being limited to the case, any other high magnetic permeability material such as an aluminous ferrous alloy or a permalloy can be used according to, for example, the frequency of the electromagnetic wave EW. The sheath 24 can be omitted as needed, or can be provided only in one of the probe 21 and the probe 22.

[0071] The size of the distance D between the transmission probe 21 and the reception probe 22 is not particularly limited, and is, for example, 20 mm to 100 mm. If the distance D is greater than 100 mm, the attenuation of the electromagnetic wave EW propagating through the medium M increases, which can result in an inability to obtain sufficient reception strength. On the other hand, if the distance D is less than 20 mm, it will be technically difficult to make observations. Furthermore, if the distance D is set to be short, the gap formed near the probes 21 and 22 has a large effect, which can result in an inability to correctly measure the relative permittivity or the moisture content.

[0072] The gap is an air space formed between the medium M and the probes 21 and 22, and is formed when the probes 21 and 22 are moved in the medium M after, for example, the probes 21 and 22 are buried in the medium M from the surface of the medium M. As described later, in order to measure the relative permittivity of the medium M or the moisture content in the medium M with high accuracy, it is advantageous for the size of the gap (the thickness of the air space) to be as small as possible, but a gap of about 1 mm can typically be generated.

[0073] (Measurement unit)

[0074] Figure 3 is a block diagram illustrating the configuration of the measurement unit 30.

[0075] The measurement unit 30 includes a signal generator 31 and a communication section 32. The measurement unit 30 typically includes a network analyzer.

[0076] The signal generator 31 includes, for example, a controller 310, a signal generation section (oscillator) 311, amplifiers 312 and 314, a phase shifter 313, a mixer 315, and an AD converter 316. The signal generator 31 generates a measurement signal S1 including information on the propagation characteristics of the electromagnetic wave EW in the medium M between the micro antenna section 210 of the transmission probe 21 and the micro antenna section 220 of the reception probe 22.

[0077] The controller 310 includes a computer including, for example, a central processing unit (CPU) and a memory, and controls the respective structural elements of the measurement unit 30, examples of which include the signal generation section 311 and the communication section 32.

[0078] The signal generation section 311 generates a signal F of a predetermined frequency in response to a frequency instruction F(n) given by the controller 310, and inputs the signal F to the transmission probe 21 via the amplifier 312 and the output terminal 34. The signal generation section 311 generates a pulsed wave (pulse signal) as the signal F, but can be configured to generate a continuous wave as the signal F.

[0079] The signal generation unit 311 may include a frequency sweeping function for the signal F. In this case, the signal generation unit 311 generates a signal F with a frequency band of, for example, 500MHz to 8GHz, based on instructions given by the controller 310.

[0080] Phase shifter 313 separates signal F into two signals with a 90-degree phase difference and inputs these two signals to mixer 315. Mixer 315 mixes the received signal with the two signals output from phase shifter 313 to modulate these signals into two response signals (I / Q signals). The received signal is input from receiver probe 22 via input terminal 35 and amplifier 314, and the two response signals are orthogonal to each other. These response signals are converted from analog signals to digital signals via AD converter 316, and a measurement signal S1 is generated based on these response signals by controller 310.

[0081] Phase shifter 313 and mixer 315 form an orthogonal detector that performs quadrature detection (IQ detection) on the output of receiver probe 22. The sum of the squares of the I and Q signals corresponds to the strength of the received signal, the square root of the sum of the squares of the I and Q signals corresponds to the amplitude of the received signal, and the arctangent of the I and Q signals corresponds to the phase.

[0082] The communication unit 32 includes a communication module, which includes, for example, an antenna for communication. The communication unit 32 is used to wirelessly transmit the measurement signal S1 from the sensor device 10 to the signal processing unit 50. This enables the measurement signal S1 to be provided to the signal processing unit 50 located at a different position than the observation point. Not limited to the above, the sensor device 10 can also be connected to the signal processing unit 50 via, for example, a power cable.

[0083] (Signal Processing Unit)

[0084] like Figure 2 As shown, the signal processing unit 50 includes a delay time calculator 51, a relative permittivity calculator 52, a moisture content calculator 53, and a memory 54. The signal processing unit 50 is an information processing device that measures the moisture content in the medium M based on the measurement signal S1 transmitted from the sensor device 10 (measuring unit 30).

[0085] Information processing devices can be implemented using hardware components (such as CPU, random access memory (RAM), and read-only memory (ROM)) and necessary software, similar to those used in computers. As alternatives to or supplements to the CPU, programmable logic devices (PLDs), such as field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or application-specific integrated circuits (ASICs) can be used.

[0086] In the present embodiment, the delay time calculator 51, the relative permittivity calculator 52, and the moisture content calculator 53 are realized as functional blocks by causing the CPU to execute a specific program. The memory 54 is realized by, for example, a ROM of the signal processing unit 50. Of course, each block can be realized using a dedicated hardware such as an integrated circuit (IC). The program is installed on the signal processing unit 50 via, for example, various recording media. Alternatively, the program can be installed via, for example, the Internet.

[0087] The delay time calculator 51 is configured to calculate a propagation delay time of the electromagnetic wave EW between the transmission probe 21 (the micro antenna portion 210) and the reception probe 22 (the micro antenna portion 220) on the basis of the measurement signal S1.

[0088] The propagation delay time of the electromagnetic wave EW is a propagation time of the electromagnetic wave EW in the medium M. The propagation delay time of the electromagnetic wave depends on the relative permittivity of the transmission path, and the propagation delay time is proportional to the square root of the relative permittivity of the medium. In general, the relative permittivity of soil itself is approximately 1 to approximately 10, and varies with the moisture content. Thus, this indicates that if the propagation delay time can be measured, the moisture content in the medium M will be able to be indirectly measured.

[0089] The method for calculating the propagation delay time is not particularly limited, and in the present embodiment, the measurement signal S1 is subjected to inverse Fourier transform (IFFT) to obtain an impulse response, and the impulse delay time is calculated from the peak position of the impulse response. The propagation delay time of the electromagnetic wave EW is calculated by subtracting the transmission time (cable transmission time) of the probe 21 and the probe 22 from the impulse delay time.

[0090] The relative permittivity calculator 52 is configured to calculate the relative permittivity of the medium M on the basis of the propagation delay time of the electromagnetic wave EW calculated by the delay time calculator 51. The relative permittivity of water is generally 80.

[0091] The moisture content calculator 53 is configured to calculate the moisture content in the medium M on the basis of the relative permittivity calculated by the relative permittivity calculator 52. For example, the moisture content is calculated using the Topp formula (described later), and the volumetric water content ratio [%] in the medium M is calculated as the moisture content.

[0092] For example, the signal processing unit 50 can further include a communication portion capable of communicating with the communication portion 32 of the measurement unit 30, and a display portion on which information on, for example, the propagation delay time, the relative permittivity, and the moisture content calculated in each functional block can be displayed.

[0093] [Moisture content measurement method]

[0094] Hereinafter, the signal processing unit 50 is described in detail together with typical operation of the water content measuring apparatus.

[0095] Figure 4 is a flowchart of the water content measuring method.

[0096] First, as shown in FIG. 1, the transmitting probe 21 and the receiving probe 22 are buried in the soil M (step S101). The facing distance D between the transmitting probe 21 and the receiving probe 22 is, for example, 50 mm. Figure 1

[0097] Subsequently, electromagnetic waves EW are transmitted and received between the transmitting probe 21 (micro antenna section 210) and the receiving antenna (micro antenna section 220) (step S102, frequency sweep).

[0098] The measurement unit 30 changes the frequency of the transmission signal F(n) transmitted to the transmitting probe 21 at a step of 10 MHz while generating a measurement signal S1 including the quadrature frequency response signals (I(n) signal and Q(n) signal) of the reception signal output from the receiving probe 22, and transmits the measurement signal S1 to the signal processing unit 50.

[0099] Subsequently, the signal processing unit 50 (delay time calculator 51) compares the transmitted electromagnetic signal and the received electromagnetic signal to calculate the propagation delay time of the electromagnetic waves EW between the transmitting probe 21 and the receiving probe 22 (step S103).

[0100] The delay time calculator 51 performs inverse fast Fourier transform (IFFT) to obtain the impulse response h(τ) from the response signals, where the I(n) signal is the real part and the Q(n) signal is the imaginary part.

[0101] h(τ) = IFFT {I(n), Q(n)}... (1)

[0102] The delay time calculator 51 obtains the pulse delay time τ [s] from the peak position of the impulse response h(τ), and subtracts the cable transmission time τ0 [s] from the pulse delay time τ to obtain the propagation delay time τ delay [s].

[0103] τ delay = τ - τ0... (2)

[0104] Subsequently, the signal processing unit 50 (relative permittivity calculator 52) calculates the relative permittivity ε r of the medium M, where the propagation delay time is τ delay [s], the speed of light is c [m / s], and the distance (D) between the probes is d [m] (step S104).

[0105] ​τ delay = d - V (ε r ) / c…(3)

[0106] Subsequently, the signal processing unit 50 (moisture content calculator 53) calculates the moisture content (volume water content ratio) θ [%] in the medium M using the Topp formula.

[0107] θ = -5.3 x 10 -2 + 2.92 x 10 -2 ε r - 5.5 x 10 -4 ε r 2 + 4.3 x 10 -6 ε r 3 …(4)

[0108] As described above, the relative permittivity of the medium M and the volume water content ratio in the medium M are calculated (step S106).

[0109] The signal processing unit 50 calculates the relative permittivity of the medium M and the volume water content ratio in the medium M based on the propagation delay time of the electromagnetic wave EW between the transmission probe 21 and the reception probe 22 in the medium M. The distance D (50 mm) between the two probes 21 and 22 is much larger than the gap (1 mm) produced in the vicinity of each of the probe 21 and the probe 22, and thus the influence of these gaps on the measurement of the relative permittivity is small. This makes it possible to prevent measurement errors due to the gaps, and the measurement accuracy of the relative permittivity of the medium M and the volume water content ratio in the medium M is improved.

[0110] (Comparative Example 1)

[0111] It has been described above that the sensor head 20 includes one transmission micro-antenna portion 210 provided to the transmission probe 21, and one reception micro-antenna portion provided to the reception probe 22. Here, for example, by providing a plurality of transmission micro-antenna portions and a plurality of reception micro-antenna portions to the transmission probe 21 and the reception probe 22, respectively, it is possible to measure the volume water content in the medium at different depths. Figure 5 An example of the configuration of the sensor device 10' including two transmission micro-antenna portions and two reception micro-antenna portions is illustrated.

[0112] Figure 5 The sensor device 10' illustrated in FIG. 12 is similar to the sensor device 10 of the basic configuration in that it has a transmission probe 21, a reception probe 22, and a measurement unit 30, and differs from the sensor device 10 in that the transmission probe 21 and the reception probe 22 each include a plurality of micro-antenna portions. Note that, Figure 5The X-axis, Y-axis, and Z-axis in the drawing represent the directions of three axes orthogonal to each other.

[0113] In the sensor device 10', the transmission probe 21 and the reception probe 22 are linearly formed in parallel to the Z-axis direction, respectively, and each includes a plurality of openings H1 and H2 and a plurality of openings H1' and H2'.

[0114] The opening H1 is a first transmission micro-antenna portion provided at the tip of the transmission probe 21. The opening H2 is a second transmission micro-antenna portion provided at an intermediate position between the tip of the transmission probe 21 and the base end on the side of the measurement unit 30.

[0115] The opening H1' is a first reception micro-antenna portion provided at the tip of the reception probe 22. The opening H2' is a second reception micro-antenna portion provided at an intermediate position between the tip of the reception probe 22 and the base end on the side of the measurement unit 30.

[0116] The lengths of the transmission probe 21 and the reception probe 22 are equal. The openings H1 and H1' face each other in the Y-axis direction, and the openings H2 and H2' face each other in the Y-axis direction.

[0117] For example, the distance (D) between the probe 21 and the probe 22 is 50 mm, the distance from the base end of the probe 21, the probe 22 to the opening H2, the opening H2' is 80 mm, and the distance from the opening H2, the opening H2' to the opening H1, the opening H1' is also 80 mm. These are examples of the dimensions of the respective portions. Note that the coaxial cables for the respective openings H1, H2, H1', and H2' each have an axial length of 6.0 mm.

[0118] The sensor device 10' having such a configuration includes two pairs of antenna portions (one pair of openings H1 and H1' and one pair of openings H2 and H2') for transmission and reception, in which the transmission antenna portion and the reception antenna portion in each pair of antenna portions face each other. Thus, it is possible to simultaneously measure the moisture content in the medium at a distance (depth) of 80 mm from the measurement unit 30 and the moisture content in the medium at a distance (depth) of 160 mm from the measurement unit 30.

[0119] However, it has been proven that when the measurement distance between a certain micro opening provided at the transmission-side probe and a certain micro opening provided at the reception-side probe is equal to the measurement distance (total length of the signal transmission path) between another micro opening provided at the transmission-side probe and another micro opening provided at the reception-side probe, the paths inadvertently have equal propagation lengths. The inventors have found that this results in the generation of noise and thus in measurement errors.

[0120] Figure 6 The schematic illustration in Figure 5The pattern of the path for transmitting the signal F in the sensor device 10' shown in FIG. 1 is shown in Table 1. Figure 6 The probe length (the length of the path in each probe), the air length (the length of the path between the two probes), and the total length of the probe length and the air length in the mode of each transmission path are given in Table 1.

[0121] [Table 1]

[0122] [Units: mm]

[0123]

[0124] In Table 1, since the dielectric constant has an influence on the measurement when the signal passes through the transmission path, the measured value of the probe length in the parentheses is multiplied by v(2.1) = 1.45 in consideration of the relative dielectric constant (for example, 2.1) of the insulating material (such as PTFE) for protecting the coaxial cable.

[0125] In Figure 6 In the case of the transmission path mode 1-(1), the signal F is transmitted in the following order: the base end of the transmitting probe 21 -> the opening H2 -> the medium -> the opening H2' -> the base end of the receiving probe 22.

[0126] In the case of the transmission path mode 1-(2), the signal F is transmitted in the following order: the base end of the transmitting probe 21 -> the opening H2 -> the medium -> the opening H1' -> the base end of the receiving probe 22.

[0127] In the case of the transmission path mode 1-(3), the signal F is transmitted in the following order: the base end of the transmitting probe 21 -> the opening H2 -> the opening H1 -> the medium -> the opening H2' -> the base end of the receiving probe 22.

[0128] In the case of the transmission path mode 1-(4), the signal F is transmitted in the following order: the base end of the transmitting probe 21 -> the opening H2 -> the opening H1 -> the opening H2 (reflection) -> the medium -> the opening H2' -> the base end of the receiving probe 22.

[0129] In the case of the transmission path mode 1-(5), the signal F is transmitted in the following order: the base end of the transmitting probe 21 -> the opening H2 -> the opening H1 -> the medium -> the opening H1' -> the opening H2' -> the base end of the receiving probe 22.

[0130] In the case of the transmission path mode 1-(6), the signal F is transmitted in the following order: the base end of the transmitting probe 21 -> the opening H2 -> the medium -> the opening H2' -> the opening H1' -> the opening H2' (reflection) -> the base end of the receiving probe 22.

[0131] The two probes 21 and 22 have shapes symmetrical to each other, and respective corresponding openings of the two probes 21 and 22 are located in symmetrical positions. Therefore, the two transmission path patterns 1-(2) and 1-(3) provide equal total lengths of transmission paths of the signal F, and the three transmission path patterns 1-(4), 1-(5), and 1-(6) provide equal total lengths of transmission paths of the signal F. Thus, it is difficult to accurately determine the difference in the measurement signal caused by these six transmission path patterns.

[0132] Figure 7 is a graph illustrating an example of a result of a test measurement performed by using the sensor device 10' shown in Figure 5 is a graph illustrating an example of a result of a test measurement performed by using the sensor device 10' shown in

[0133] As shown in Figure 7 in FIG. 6, a power peak (response output) corresponding to the transmission path pattern 1-(1) is observed around time 1.2 [ns].

[0134] Further, power peaks corresponding to the transmission path patterns 1-(2) and 1-(3), respectively, are observed around time 1.7 [ns].

[0135] In addition, power peaks corresponding to the transmission path patterns 1-(4), 1-(5), and 1-(6), respectively, are observed around time 2.1 [ns].

[0136] This indicates that, as described above, when the probe configuration of the sensor device 10' is adopted, the power peaks (response outputs) of the plurality of signal transmission path patterns are not separated (overlap) on the time axis. Therefore, when the probe configuration of the sensor device 10' is adopted, different signal transmission path patterns can provide equal measurement distances (total lengths), which leads to generation of noise (measurement error). In other words, it is difficult to accurately measure the moisture content at different positions in the medium.

[0137] Therefore, an object of the present embodiment is to suppress a decrease in measurement accuracy due to a difference between signal transmission paths of a plurality of signal transmission paths in a sensor device including a transmission probe and a reception probe each including a plurality of micro antenna portions. Embodiments of the present technology are described below.

[0138] <First Embodiment>

[0139] (When there are two openings)

[0140] Figure 8 A configuration of a sensor device 10A according to the first embodiment of the present technology is schematically illustrated.

[0141] The sensor device 10A of the present embodiment includes a sensor head 20A and a measurement unit 30. The above-described sensor device 10A and a signal processing unit 50 are included in a moisture content measuring device (the same applies to the following description).

[0142] The sensor head 20A includes a transmission probe 21 (first probe) and a reception probe 22 (second probe).

[0143] The transmission probe 21 includes a first transmission micro-antenna portion 211 (opening H1) and a second transmission micro-antenna portion 212 (opening H2).

[0144] The reception probe 22 is arranged at a predetermined distance from the transmission probe 21, and includes a first reception micro-antenna portion 221 (opening H1') and a second reception micro-antenna portion 222 (opening H2').

[0145] The measurement unit 30 includes a controller 310 (see Figure 3 ), which generates a measurement signal S1 including information on an electromagnetic wave propagation characteristic in a medium between the first transmission micro-antenna portion 211 and the first reception micro-antenna portion 221, and information on an electromagnetic wave propagation characteristic in a medium between the second transmission micro-antenna portion 212 and the second reception micro-antenna portion 222.

[0146] The measurement unit 30 has a configuration similar to that of the measurement unit 30 of the sensor device 10 of the basic configuration. Therefore, detailed description of the above-described configuration is omitted here. The sensor head 20A is described in detail below. In the following description, the respective end portions of the transmission probe 21 and the reception probe 22 on the side of the measurement unit 30 are each also referred to as a base end, and the respective opposite end portions of the transmission probe 21 and the reception probe 22 are each also referred to as a tip end.

[0147] The transmission probe 21 is linearly formed in parallel to the Z-axis direction from the base end to the tip end. The first transmission micro-antenna portion 211 corresponds to the opening H1 formed in the tip end of the transmission probe 21. The second transmission micro-antenna portion 212 corresponds to the opening H2 formed at an intermediate position between the base end and the tip end of the transmission probe 21.

[0148] The reception probe 22 includes a straight portion 22a connected to the measurement unit 30 and parallel to the Z-axis direction, and a bent portion 41 bent from the straight portion 22a toward the tip end of the reception probe 22.

[0149] The straight portion 22a is arranged at a distance D from the transmission probe 21 in the Y-axis direction.

[0150] The bent portion 41 includes a first portion 41a extending from the straight portion 22a in a direction opposite to the emission probe 21 in parallel to the Y-axis direction, a second portion 41b extending from the first portion 41a in parallel to the Z-axis direction, and a third portion 41c extending from the second portion 41b in a direction close to the emission probe 21 in parallel to the Y-axis direction. The tip of the third portion 41c is the tip of the reception probe 22, and is located at a distance D from the tip of the emission probe 21 while facing the tip of the emission probe 21 in the Y-axis direction.

[0151] The first reception micro-antenna portion 221 corresponds to an opening H1' formed in the tip of the reception probe 22. The second reception micro-antenna portion 222 corresponds to an opening H2' provided to the end of the first portion 41a on the straight portion 22a side. The bent portion 41 is provided between the opening H1' and the opening H2'.

[0152] The openings H1 and H1' face each other at a distance D in the Y-axis direction. Likewise, the openings H2 and H2' face each other at a distance D in the Y-axis direction.

[0153] Note that the bent portion 41 of the reception probe 22 is not limited to having a crank-like shape (U shape) as described above, and the bent portion 41 can have a curved shape. Furthermore, the emission probe 21 can be formed in a bent shape, and the reception probe 22 can be formed in a straight shape. In other words, it is enough that the two probes have shapes that are not symmetrical to each other in the YZ plane or the ZX plane.

[0154] In the sensor device 10A of the present embodiment, the emission probe 21 and the reception probe 22 have different probe lengths, as described above. The probe length of the emission probe 21 refers to the length in the Z-axis direction (axial length), and the probe length of the reception probe 22 refers to the length that is the sum of the axial length L1 corresponding to the straight portion 22a and the sum (L2+L3+L2) of the axial lengths of the first portion 41a to the third portion 41c included in the bent portion 41. In other words, the probe length of the reception probe 22 is larger than the probe length of the emission probe 21 by a length corresponding to 2 x L2.

[0155] For example, the distance (D) between the probe 21 and the probe 22 is 50 mm, L1 is 80 mm, L2 is 40 mm, and L3 is 80 mm. These are examples of the dimensions of the respective portions. The coaxial cables for the respective openings H1, H2, H1', and H2' each have an axial length of 6.0 mm.

[0156] In the sensor device 10A having the above-described configuration, the measurement unit 30 transmits the signal F from the openings H1, H2 of the transmitting probe 21, and measures a propagation characteristic of the signal F received at the openings H1, H2' of the receiving probe 22 through the medium.

[0157] Figure 9 The path patterns of the transmission of the signal F in the sensor device 10A shown in Figure 8 Table 2. The probe length (the path length in each probe), the air length (the path length between the two probes), and the total length of the probe length and the air length in each of the transmission path patterns are given in Table 2. Figure 9

[0158] [Table 2]

[0159] [Units: mm]

[0160]

[0161] In Table 2, since the dielectric constant has an influence on the measurement when the signal passes through the transmission path, the measured value of the probe length in the parentheses is multiplied by v(2.1) = 1.45 in consideration of the relative dielectric constant (for example, 2.1) of the insulating material (such as PTFE) for protecting the coaxial cable. The portion a in the total length corresponds to the length of the bend portion for bending the coaxial cable at a substantially right angle to form the coaxial cable in a U shape.

[0162] In Figure 9 Table 2, in the case of the transmission path pattern 2-(1), the signal F is transmitted in the following order: the base end of the transmitting probe 21 -> the opening H2 -> the medium -> the opening H2' -> the base end of the receiving probe 22.

[0163] In the case of the transmission path pattern 2-(2), the signal F is transmitted in the following order: the base end of the transmitting probe 21 -> the opening H2 -> the opening H1 -> the medium -> the opening H2' -> the base end of the receiving probe 22.

[0164] In the case of the transmission path pattern 2-(3), the signal F is transmitted in the following order: the base end of the transmitting probe 21 -> the opening H2 -> the opening H1 -> the opening H2 (reflection) -> the medium -> the opening H2' -> the base end of the receiving probe 22.

[0165] In the case of the transmission path pattern 2-(4), the signal F is transmitted in the following order: the base end of the transmitting probe 21 -> the opening H2 -> the medium -> the opening H1' -> the bend portion 41 -> the opening H2' -> the base end of the receiving probe 22.

[0166] ​In the case of transmission path pattern 2-(5), the signal F is transmitted in the following order: base end of the transmitting probe 21 → opening H2 → opening H1 → medium → opening H1' → bending portion 41 → opening H2' → base end of the receiving probe 22.

[0167] Since the bending portion 41 is provided at the receiving probe 22, the transmitting probe 21 and the receiving probe 22 have shapes that are not symmetrical to each other, and all of the above transmission path patterns provide different total lengths.

[0168] Figure 10 is a graph illustrating an example of results of test measurements performed by transmitting and receiving an electromagnetic wave EW of a predetermined frequency using the sensor device 10A of Figure 8 In this graph, the horizontal axis represents time (unit: ns), and the vertical axis represents power (unit: dB).

[0169] As shown in Figure 10 , a power peak (response output) corresponding to transmission path pattern 2-(1) is observed around time 1.2 [ns].

[0170] Further, a power peak corresponding to transmission path pattern 2-(2) is observed around time 1.7 [ns]. This power peak is about 26% smaller than the power peak of signal transmission path pattern 2-(5) that is the main path. Therefore, separation on the time axis is not required.

[0171] In addition, a power peak corresponding to transmission path pattern 2-(3) is observed around time 2.1 [ns], and a power peak corresponding to transmission path pattern 2-(4) is observed around time 2.3 [ns]. Further, a power peak corresponding to transmission path pattern 2-(5) is observed around time 2.6 [ns].

[0172] This indicates that, as described above, when the probe configuration of the sensor device 10A is adopted, the power peaks (response outputs) of the respective signal transmission path patterns are separated (not overlapped) on the time axis. Therefore, when the sensor device 10A of the present embodiment is adopted, the different signal transmission path patterns do not provide equal measurement distances (total lengths), which makes it possible to reduce measurement errors. This makes it possible to improve the measurement accuracy of the relative permittivity of the medium and the moisture content in the medium.

[0173] Figure 11 is a graph in which the measurement results shown in Figure 7 and Figure 10 are overlapped.

[0174] In Comparative Example 1 Figure 7 , the signals F are overlapped, and therefore the power peaks are not separated. On the other hand, in the present embodiment Figure 10In the asymmetric type, the power peak is separated. Except for the single point (2-(2)), the propagation time in the present embodiment is longer than that in the comparative example, so it is clear that the propagation distance and the time are associated with each other. The point (i in the drawing) showing the power peak of the comparative example and the present embodiment is simultaneously shown as a reference of the separation of the power peak.

[0175] (Regarding resolution)

[0176] When Δf is the frequency band of the measurement signal S1, the time resolution Δt of the measurement signal S1 that has been inverse Fourier-transformed is represented as follows.

[0177] Δt = 1 / Δf

[0178] When c is the speed of light (3.0 x 10 8 [m / s]), the following relationship is satisfied when converted into a distance in a vacuum.

[0179] Δλ = c / Δf

[0180] The effective wavelength Δλg of the frequency band Δf in a medium whose refractive index is n is represented as follows.

[0181] Δλg = c / nΔf

[0182] The refractive index n is obtained by multiplying the relative dielectric constant εr by the relative magnetic permeability μr and taking the square root of the product value, and is represented by n = V(εrμr).

[0183] In order to separate the adjacent peaks of each signal transmission path mode between the transmission probe 21 and the reception probe 22, the distance Δd between the probe 21 and the probe 22 must be greater than or equal to Δλg. In other words, the following relationship is satisfied.

[0184] Δd > Δλg x X

[0185] Here, X is a coefficient determined by the materials of the probe 21 and the probe 22, and can be 1.

[0186] When the material of the insulating material of the coaxial cable is polytetrafluoroethylene (PTFE, whose relative dielectric constant εr is 2.1), the effective wavelength Δλg when Δf is 9 GHz is represented as follows.

[0187] Δλg = 1 / V(εr of PTFE) x (wavelength of measurement frequency band)

[0188] = 1 / V(2.1) x 33.3103

[0189] = 22.97 mm = 2.297 cm

[0190] Therefore, when the measurement frequency band is 9 GHz and the insulation material of the coaxial cable is PTFE, the distance Δd between probe 21 and probe 22 must be greater than or equal to 2.3 cm. Similarly, when the measurement frequency band is between 1 GHz and 9 GHz and the insulation material of the coaxial cable is PTFE, the distance Δd between probe 21 and probe 22 must be greater than or equal to 2.6 cm.

[0191] Similarly, when the measurement frequency band is greater than or equal to 10 GHz (i.e., sweeping from 0 GHz to 10 GHz) and when the insulation material of the coaxial cable is PTFE, the distance Δd between probe 21 and probe 22 must be greater than or equal to 2.06 cm (see Table 3).

[0192] [Table 3]

[0193]

[0194] Here, it is assumed that any two adjacent path patterns of the signal transmission path between probe 21 and probe 22 are Figure 12 The diagram shows paths A and B. It is assumed that for medium M, coaxial cable, and the like, no different types are used for path A (one of the paths) and path B (the other of the paths). When n N and d AN Let n be the refractive index in path A and the distance between the openings (micro-antenna section), respectively, and n be the distance between the openings (micro-antenna section). N and d BN When the refractive index in path B and the distance between the opening (micro-antenna section) are respectively, the propagation time T through path A is expressed by the following formula. A .

[0195] [Mathematical Expression 1]

[0196]

[0197] Here, c0 is the speed of light (3.0 × 10⁻⁶). 8 [m / s]).

[0198] The propagation time T via path B can be expressed using the formula shown below. B .

[0199] [Mathematical Expression 2]

[0200]

[0201] When T A With T B If the difference between them is greater than or equal to 1 / Δf, the aforementioned adjacent peaks are separated. When converted to distance, the following relationship holds.

[0202] [Math. 3]

[0203]

[0204] Figure 8 The sensor head 20A of the sensor device 10A shown in FIG. 1 includes first signal transmission paths and second signal transmission paths.

[0205] The first signal transmission paths are paths passing between the opening H1 (the first transmission micro antenna portion 211) and the opening H1' (the first reception micro antenna portion 221), or paths passing between the opening H1 (the first transmission micro antenna portion 211) and the opening H2' (the second reception micro antenna portion 222). In the example of FIG. 1, the first signal transmission paths correspond to transmission path patterns 2-(2) and 2-(5). Figure 9

[0206] The second signal transmission paths are paths passing between the opening H2 (the second transmission micro antenna portion 212) and the opening H1' (the first reception micro antenna portion 221), or paths passing between the opening H2 (the second transmission micro antenna portion 212) and the opening H2' (the second reception micro antenna portion 222). In the example of FIG. 1, the second signal transmission paths correspond to transmission path patterns 2-(1), 2-(3), and 2-(4). Figure 9

[0207] Further, in the sensor head 20A, the path length difference between these first signal transmission paths, the path length difference between these second signal transmission paths, and the path length difference between the first signal transmission paths and the second signal transmission paths are each set to be greater than or equal to a predetermined effective wavelength (for example, greater than or equal to 2.06 cm) to satisfy the formula [Math. 3].

[0208] Alternatively, assuming that two arbitrary adjacent path patterns of the signal transmission path patterns between the probe 21 and the probe 22 as described later are Figure 13 Path A and Path B shown in FIG. 2. Here, it is assumed that different types can be used for Path A and Path B with respect to the medium M, a coaxial cable, and the like. In other words, when n N and d AN are the refractive index and the distance between the opening (described later) in Path A, respectively, and n M and d BM are the refractive index and the distance between the opening (the micro antenna portion) in Path B, respectively (N≠M, n N ≠n M ), the propagation time T A propagating through Path A is expressed using the formula shown below.

[0209] [Math. 4]​​

[0210]

[0211] The propagation time T through the path B is expressed using the formula shown below B .

[0212] [Math. 5]

[0213]

[0214] When the difference between T A and T B is greater than or equal to 1 / Δf, the above-mentioned adjacent peaks are separated. When converted to distance, the following relationship is satisfied.

[0215] [Math. 6]

[0216]

[0217] Also in this case, in the sensor head 20A, the path length difference between the first signal transmission paths, the path length difference between the second signal transmission paths, and the path length difference between the first signal transmission path and the second signal transmission path are each set to satisfy the formula [Math. 6].

[0218] [Second Embodiment]

[0219] Figure 14 The configuration of the sensor device 10B according to the second embodiment of the present technology is schematically illustrated.

[0220] The sensor device 10B according to the present embodiment includes a sensor head 20B and a measurement unit 30. In the following description, mainly the structural elements different from those of the first embodiment are described. The structural elements similar to those of the first embodiment are indicated by the reference numerals similar to those used in the first embodiment, and the explanation of the above-mentioned structural elements is omitted or simplified.

[0221] In the sensor head 20B of the present embodiment, the emission probe 21 is arranged in parallel to the Z-axis direction, and includes a folding portion 42 which reversely orients the tip 23 of the emission probe 21 in the direction of the measurement unit 30. An opening H1 serves as a first emission micro-antenna portion provided to the folding portion 42, and an opening H2 serves as a second emission micro-antenna portion provided to the tip 23 of the emission probe 21.

[0222] In the sensor head 20B of the present embodiment, the receiving probe 22 is arranged in parallel to the Z-axis direction, and has a probe length equal to the length from the base end of the transmitting probe 21 to the folding portion 42. The opening H1' serves as a first receiving micro-antenna portion provided at the tip end 23 of the receiving probe 22, and the opening H2' serves as a second receiving micro-antenna portion provided at an intermediate position between the base end and the tip end 23 of the receiving probe 22.

[0223] The opening H1' of the receiving probe 22 faces the opening H1 of the transmitting probe 21 at a predetermined distance in the Y-axis direction, and the opening H2' of the receiving probe 22 faces the opening H2 of the transmitting probe 21 at a predetermined distance in the Y-axis direction.

[0224] As described above, the transmitting probe 21 and the receiving probe 22 in the sensor head 20B of the present embodiment have different probe lengths. This makes it possible to provide similar effects to those of the first embodiment described above.

[0225] As Figure 14 indicated in FIG. 6, it is assumed that the (signal transmission) path from the base end of the transmitting probe 21 to a predetermined position located before the folding portion and facing the opening H2 is path 1, the path from the predetermined position to the opening H1 is path 2, and the path from the base end of the receiving probe 22 to the opening H2' is path 3.

[0226] Further, it is assumed that the path from the opening H2' to the opening H1' is path 4, the path (medium) from the opening H2 to the opening H2' is path 5, the path (medium) from the opening H1 to the opening H1' is path 6, and the path from the opening H1 through the folding portion 42 to the opening H2 is path 7. Here, path 1 = path 3, path 2 = path 4 ≠ path 7, and path 5 = path 6.

[0227] Consider a case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H2.

[0228] The main path to obtain a response output is "path 1 → path 2 → path 7 → path 5 → path 3". In this case, the total (path) length is obtained by "path 1 x 2 + path 5 x 1 + path 7 x 1". Another path is "path 1 → path 2 → path 7 → path 7 → path 7 → path 5 → path 3 (reflected at the opening H1)". In this case, the total length is obtained by "path 1 x 2 + path 2 x 1 + path 5 x 1 + path 7 x 3".

[0229] Another path is "path 1→ path 2→ path 6→ path 4→ path 4→ path 4→ path 3 (reflection at opening H2' )". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 5 x 1". Still another path is "path 1→ path 2→ path 7→ path 7→ path 7→ path 5→ path 4→ path 4→ path 3 (reflections at openings H2 and H2' )". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 5 x 1 + path 7 x 2".

[0230] Next, consider the case where a signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening Hl.

[0231] The main path to obtain a response output is "path 1→ path 2→ path 6→ path 4→ path 3". In this case, the total (path) length is obtained by "path 1 x 2 + path 2 x 2 + path 5 x 1". Another path is "path 1→ path 2→ path 7→ path 7→ path 6→ path 4→ path 3 (reflection at opening H2)". The total length in this case is obtained by "path 1 x 2 + path 2 x 2 + path 5 x 1 + path 7 x 2".

[0232] Another path is "path 1→ path 2→ path 6→ path 4→ path 4→ path 4→ path 3 (reflection at opening H2' )". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 5 x 1". Still another path is "path 1→ path 2→ path 7→ path 7→ path 6→ path 4→ path 4→ path 4→ path 3 (reflections at openings H2 and H2' )". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 5 x 1 + path 7 x 2".

[0233] As shown in Figure 14 When the opening H2 is disposed at the tip of the transmitting probe 21 with the transmitting probe 21 and the receiving probe 22 parallel to each other and with "path 1 = path 3", "path 2 = path 4 ≠ path 7", and "path 5 = path 6" satisfied, none of the above path patterns provide equal propagation lengths (total lengths), as shown in FIG. 6. Here, since path 7 includes the folding portion 42, path 7 has a larger path length than paths 2 and 4.

[0234] Furthermore, even if the distance corresponding to path 5 and / or path 6 changes, none of the above path patterns provide equal propagation lengths, as will be described later.

[0235] As described above, none of the path patterns through the openings Hl and H2 provide equal total lengths. In other words, the total lengths provided by all of the above signal transmission patterns are different.

[0236] Accordingly, the power peaks (response outputs) with respect to the respective signal transmission path patterns are separated (not overlapped) on the time axis. Thus, Figure 14 The sensor head 20B enables prevention of provision of equal measurement distances (total lengths) by different signal transmission path patterns, and thus reduction of measurement errors. This enables improvement of measurement accuracy of the relative permittivity of a medium or the moisture content in a medium.

[0237] Note that the folding portion 42 is not limited to the example provided on the transmission probe 21, and the folding portion 42 can be provided on the reception probe 22. In this case, an effect similar to the above-described effect is also provided.

[0238] <Third Embodiment>

[0239] Figure 15 The configuration of the sensor device 10C according to the third embodiment of the present technology is schematically illustrated.

[0240] The sensor device 10C of the present embodiment includes a sensor head 20C and a measurement unit 30. In the following description, mainly the structural elements different from those of the first embodiment are described. The structural elements similar to those of the first embodiment are indicated by reference numerals similar to those used in the first embodiment, and the description of the above-described structural elements is omitted or simplified.

[0241] The present embodiment differs from the first and second embodiments in that the distance between the first transmission micro-antenna portion and the first reception micro-antenna portion and the distance between the second transmission micro-antenna portion and the second reception micro-antenna portion are different from each other.

[0242] In the sensor head 20C of the present embodiment, the transmission probe 21 has a straight shape parallel to the Z-axis direction. The opening H1 serving as the first transmission micro-antenna portion is provided at the tip end 23 of the transmission probe 21, and the opening H2 serving as the second transmission micro-antenna portion is provided at an intermediate position between the base end and the tip end 23 of the transmission probe 21.

[0243] The reception probe 22 has a straight shape inclined at a predetermined angle in the Y-axis direction with respect to the Z-axis direction, and is arranged so as not to be parallel to the transmission probe 21. The opening H1' serving as the first reception micro-antenna portion is provided at the tip end 23 of the reception probe 22, and the opening H2' serving as the second reception micro-antenna portion is provided at an intermediate position between the base end and the tip end 23 of the reception probe 22.

[0244] The opening H1' of the receiving probe 22 faces the opening H1 of the transmitting probe 21 at a predetermined distance in the Y-axis direction from the opening H1 of the transmitting probe 21, and the opening H2' of the receiving probe 22 faces the opening H2 of the transmitting probe 21 at a distance greater than the predetermined distance in the Y-axis direction from the opening H2 of the transmitting probe 21.

[0245] When one of the probes 21 and 22 is tilted with respect to the other of the probes 21 and 22, this makes the two distances between the micro antenna sections of the respective probes 21 and 22 different, as described above.

[0246] As shown in FIG. 6, assume that the (signal transmission) path from the base end of the transmitting probe 21 to the opening H2 is path 1, the path from the opening H2 to the opening H1 is path 2, and the path from the base end of the receiving probe 22 to the opening H2' is path 3. Figure 15

[0247] Further, assume that the path from the opening H2' to the opening H1' is path 4, the path (medium) from the opening H2 to the opening H2' is path 5, and the path (medium) from the opening H1 to the opening H1' is path 6. Here, path 5 ≠ path 6, path 1 = path 3, and path 2 = path 4.

[0248] Consider the case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H2.

[0249] The main path to obtain a response output is "path 1 → path 5 → path 3". In this case, the total (path) length is obtained by "path 1 x 1 + path 3 x 1 + path 5 x 1". Another path is "path 1 → path 2 → path 2 → path 5 → path 3 (reflected at the opening H1)". In this case, the total length is obtained by "path 1 x 1 + path 2 x 2 + path 3 x 1 + path 5 x 1".

[0250] Another path is "path 1 → path 5 → path 4 → path 4 → path 3 (reflected at the opening H1')". In this case, the total length is obtained by "path 1 x 1 + path 3 x 1 + path 4 x 2 + path 5 x 1". Another path is "path 1 → path 2 → path 2 → path 5 → path 4 → path 4 → path 3 (reflected at the openings H1 and H1')". In this case, the total length is obtained by "path 1 x 1 + path 2 x 2 + path 3 x 1 + path 4 x 2 + path 5 x 1".

[0251] Next, consider the case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H1.

[0252] ​The main path used to obtain the response output is "Path 1 → Path 2 → Path 6 → Path 4 → Path 3". In this case, the total (path) length is obtained by "Path 1×1 + Path 2×1 + Path 3×1 + Path 4×1 + Path 6×1". Another path is "Path 1 → Path 2 → Path 2 → Path 2 → Path 6 → Path 4 → Path 3 (reflection at opening H2). In this case, the total length is obtained by "Path 1×1 + Path 2×3 + Path 3×1 + Path 4×1 + Path 6×1".

[0253] Another path is "Path 1 → Path 2 → Path 6 → Path 4 → Path 4 → Path 4 → Path 3 (reflected at opening H2')". In this case, the total length is obtained by "Path 1×1 + Path 2×1 + Path 3×1 + Path 4×3 + Path 6×1". Another path is "Path 1 → Path 2 → Path 2 → Path 2 → Path 6 → Path 4 → Path 4 → Path 4 → Path 3 (reflected at openings H2 and H2')". In this case, the total length is obtained by "Path 1×1 + Path 2×3 + Path 3×1 + Path 4×3 + Path 6×1".

[0254] like Figure 15 As shown, when the transmitting probe 21 is arranged at a predetermined angle relative to the receiving probe 22 (so that the transmitting probe 21 and the receiving probe 22 are arranged asymmetrically) and openings H2 and H2' are provided in the case that “path 5 ≠ path 6”, “path 1 = path 3” and “path 2 = path 4”, none of the above path patterns provide equal propagation lengths (total lengths).

[0255] As mentioned above, the path patterns through opening H1 and opening H2 do not provide equal total lengths. In other words, the total lengths provided by all the signal transmission patterns described above are different.

[0256] Accordingly, the power peaks (response outputs) relative to the corresponding signal transmission path modes are separate (non-overlapping) on ​​the time axis. Therefore, Figure 15 The sensor head 20C prevents different signal transmission path modes from providing equal measurement distances (total lengths), and thus reduces measurement errors. This improves the accuracy of measuring the relative permittivity of the medium or the moisture content in the medium.

[0257] Note that when the transmitting probe 21 and the receiving probe 22 are not parallel to each other, the probes are more prone to unintentional deformation (such as bending) or unintentional air space formation around the probe when the sensor head 20C is buried in a medium such as soil. In this case, the sensor head 20C may also include a support 40 (see...). Figure 15), the support 40 supports the two probes 21 and 22 in a state of being non-parallel to each other. The support 40 can be, for example, a wiring substrate. In this case, the probe 21 and the probe 22 can be formed on the wiring substrate. The support 40 can similarly be applied to the first embodiment and the second embodiment and the embodiments described later.

[0258] <Fourth Embodiment>

[0259] Figure 16 The configuration of the sensor device 10D according to the fourth embodiment of the present technology is schematically illustrated.

[0260] The sensor device 10D of the present embodiment includes a sensor head 20D and a measurement unit 30. In the following description, mainly the structural elements different from those of the first embodiment are described. The structural elements similar to those of the first embodiment are indicated by the reference numerals similar to those used in the first embodiment, and the description of the above-described structural elements is omitted or simplified.

[0261] The present embodiment differs from the first embodiment and the second embodiment in that the distance between the first transmission micro-antenna portion and the first reception micro-antenna portion and the distance between the second transmission micro-antenna portion and the second reception micro-antenna portion are different from each other.

[0262] Further, the present embodiment differs from the third embodiment in that the transmission probe 21 and the reception probe 22 are each arranged to be inclined with respect to the Z-axis direction so that the respective tips 23 of the transmission probe 21 and the reception probe 22 are close to each other.

[0263] In the transmission probe 21, the opening H1 serving as the first transmission micro-antenna portion is provided at the tip 23 of the transmission probe 21, and the opening H2 serving as the second transmission micro-antenna portion is provided at an intermediate position between the base end and the tip 23 of the transmission probe 21.

[0264] The probe length of the reception probe 22 is equal to the probe length of the transmission probe 21, and is arranged to be non-parallel to the transmission probe 21. The opening H1' serving as the first reception micro-antenna portion is provided at the tip 23 of the reception probe 22, and the opening H2' serving as the second reception micro-antenna portion is provided at an intermediate position between the base end and the tip 23 of the reception probe 22.

[0265] The opening H1' of the reception probe 22 faces the opening H1 of the transmission probe 21 at a predetermined distance in the Y-axis direction from the opening H1 of the transmission probe 21, and the opening H2' of the reception probe 22 faces the opening H2 of the transmission probe 21 at a certain distance greater than the predetermined distance in the Y-axis direction from the opening H2 of the transmission probe 21.

[0266] When one of the probes 21 and 22 is tilted with respect to the other of the probes 21 and 22, this causes the two distances between the micro antenna sections of the respective probes 21 and 22 to be different, as described above.

[0267] As Figure 16 shown in FIG. 6, assume that the (signal transmission) path from the base end of the transmitting probe 21 to the opening H2 is path 1, the path from the opening H2 to the opening H1 is path 2, and the path from the base end of the receiving probe 22 to the opening H2' is path 3.

[0268] Further, assume that the path from the opening H2' to the opening H1' is path 4, the (spatial) path from the opening H2 to the opening H2' is path 5, and the (spatial) path from the opening H1 to the opening H1' is path 6. Here, path 5 ≠ path 6, path 1 = path 3, and path 2 = path 4.

[0269] Consider the case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H2.

[0270] The main path to obtain the response output is "path 1→path 5→path 3". In this case, the total (path) length is obtained by "path 1 x 2 + path 5 x 1". Another path is "path 1→path 2→path 2→path 5→path 3 (reflected at the opening H1)". In this case, the total length is obtained by "path 1 x 2 + path 2 x 2 + path 5 x 1".

[0271] Another path is "path 1→path 5→path 4→path 4→path 3 (reflected at the opening H1')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 2 + path 5 x 1". Yet another path is "path 1→path 2→path 2→path 5→path 4→path 4→path 3 (reflected at the openings H1 and H1')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 5 x 1".

[0272] Next, consider the case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H1.

[0273] The main path to obtain the response output is "path 1→path 2→path 6→path 4→path 3". In this case, the total (path) length is obtained by "path 1 x 2 + path 2 x 2 + path 6 x 1". Another path is "path 1→path 2→path 2→path 2→path 6→path 4→path 3 (reflected at the opening H2). In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 6 x 1".

[0274] There is also a path of "path 1→ path 2→ path 6→ path 4→ path 4→ path 4→ path 3 (reflected at opening H2')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 6 x 1". There is also a path of "path 1→ path 2→ path 2→ path 2→ path 6→ path 4→ path 4→ path 4→ path 3 (reflected at opening H2 and opening H2')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 6 + path 6 x 1".

[0275] As shown in Figure 16 When openings H2 and H2' are provided in a case where the transmission probe 21 and the reception probe 22 are each arranged to be inclined at a predetermined angle (so that the transmission probe 21 and the reception probe 22 are arranged symmetrically), and "path 5 ≠ path 6", "path 1 = path 3", and "path 2 = path 4" are satisfied, some of the above-described path patterns do not provide equal propagation lengths (total lengths), as shown in

[0276] Here, the path pattern that is reflected at opening H1 and the path pattern that is reflected at opening H1' provide equal propagation lengths. Furthermore, the path pattern that is reflected at opening H2 and the path pattern that is reflected at opening H2' provide equal propagation lengths.

[0277] However, the two sets of equal propagation lengths are not equal to the propagation length of the main path, and thus there is a time difference in the response output. Therefore, the response output can be easily separated so that noise is not generated.

[0278] As described above, some of all the path patterns through openings H1 and H2 provide equal total lengths. However, the total lengths provided by all the above-described path patterns are different from the total length of the main path.

[0279] Accordingly, the power peaks (response outputs) of the respective signal transmission path patterns are separated at important points on the time axis (overlap of the power peaks does not occur with respect to the main path). Therefore, Figure 16 The sensor head 20D makes it possible to prevent equal measurement distances (total lengths) from being provided by different signal transmission path patterns, and thus reduces measurement errors. This makes it possible to improve the measurement accuracy of the relative permittivity of a medium or the moisture content in a medium.

[0280] <5th Embodiment>

[0281] Figure 17 The configuration of the sensor device 10E according to the fifth embodiment of the present technology is schematically illustrated.

[0282] The sensor device 10E of this embodiment includes a sensor head 20E and a measurement unit 30. In the following description, structural elements that differ from those of the first embodiment are primarily described. Structural elements similar to those of the first embodiment are indicated by reference numerals similar to those used in the first embodiment, and descriptions of these structural elements are omitted or simplified.

[0283] The difference between this embodiment and the first and second embodiments is that the distance between the first transmitting micro-antenna section and the first receiving micro-antenna section is different from the distance between the second transmitting micro-antenna section and the second receiving micro-antenna section.

[0284] Furthermore, this embodiment differs from the third and fourth embodiments in that the transmitting probe 21 and the receiving probe 22 have equal probe lengths and are arranged parallel to the Z-axis direction.

[0285] In the transmitting probe 21, an opening H1, which serves as the first transmitting micro-antenna section, is provided at the end 23 of the transmitting probe 21, and an opening H2, which serves as the second transmitting micro-antenna section, is provided at the middle position between the base end and the end 23 of the transmitting probe 21.

[0286] The length of the receiving probe 22 is equal to the length of the transmitting probe 21, and it is arranged parallel to the transmitting probe 21. An opening H1' serving as a first receiving micro-antenna section is provided at the end 23 of the receiving probe 22, and an opening H2' serving as a second receiving micro-antenna section is provided at the midpoint between the base end and the end 23 of the receiving probe 22.

[0287] The opening H1' of the receiving probe 22 is positioned at a predetermined distance from the opening H1 of the transmitting probe 21 in the Y-axis direction, facing the opening H1 of the transmitting probe 21. Compared to the distance between the opening H2 of the transmitting probe 21 and the base end of the transmitting probe 21, the opening H2' of the receiving probe 22 is arranged closer to the base end of the receiving probe 22, resulting in the opening H2' facing the opening H2 at a distance greater than the predetermined distance.

[0288] When the opening H2' is offset by a predetermined amount relative to the opening H2 in the Z-axis direction, this results in two different distances between the micro-antenna portions of the corresponding probes 21 and 22, as described above. The offset of the opening H2' relative to the opening H2 is not particularly limited, and is, for example, more than 5% of the probe length.

[0289] like Figure 17 As shown, assume that the (signal transmission) path from the base of the transmitting probe 21 to the opening H2 is path 1, the path from the opening H2 to the opening H1 is path 2, and the path from the base of the receiving probe 22 to the opening H2' is path 3.

[0290] Further, assume that the path from opening H2' to opening H1' is path 4, the path (medium) from opening H2 to opening H2' is path 5, and the path (medium) from opening H1 to opening H1' is path 6. Here, path 1 ≠ path 3, path 2 = path 4, and path 5 ≠ path 6.

[0291] Consider the case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through opening H2.

[0292] The main path to obtain a response output is "path 1 → path 5 → path 3". In this case, the total (path) length is obtained by "path 1 x 1 + path 3 x 1 + path 5 x 1". Another path is "path 1 → path 2 → path 2 → path 5 → path 3 (reflected at opening H1)". In this case, the total length is obtained by "path 1 x 1 + path 2 x 2 + path 3 x 1 + path 5 x 1".

[0293] Another path is "path 1 → path 5 → path 4 → path 4 → path 3 (reflected at opening H1)". In this case, the total length is obtained by "path 1 x 1 + path 2 x 2 + path 3 x 1 + path 5 x 1". Another path is "path 1 → path 2 → path 2 → path 5 → path 4 → path 4 → path 3 (reflected at openings H1 and H1')". In this case, the total length is obtained by "path 1 x 1 + path 2 x 4 + path 3 x 1 + path 5 x 1".

[0294] Next, consider the case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through opening H1.

[0295] The main path to obtain a response output is "path 1 → path 2 → path 6 → path 4 → path 3". In this case, the total (path) length is obtained by "path 1 x 1 + path 2 x 2 + path 3 x 1 + path 6 x 1". Another path is "path 1 → path 2 → path 2 → path 2 → path 6 → path 4 → path 3 (reflected at opening H2)". In this case, the total length is obtained by "path 1 x 1 + path 2 x 4 + path 3 x 1 + path 6 x 1".

[0296] Another path is "path 1 → path 2 → path 6 → path 4 → path 4 → path 4 → path 3 (reflected at opening H2')". In this case, the total length is obtained by "path 1 x 1 + path 2 x 4 + path 3 x 1 + path 6 x 1". Another path is "path 1 → path 2 → path 2 → path 2 → path 6 → path 4 → path 4 → path 4 → path 3 (reflected at openings H2 and H2')". In this case, the total length is obtained by "path 1 x 1 + path 2 x 6 + path 3 x 1 + path 6 x 1".

[0297] As Figure 17 indicated in FIG. 1, when the opening H2 and the opening H2' are provided in a case where the transmission probe 21 and the reception probe 22 are arranged parallel to each other, and the conditions "Path 1 ≠ Path 3", "Path 2 = Path 4", and "Path 5 ≠ Path 6" are satisfied, some of the above-described path patterns do not provide equal propagation lengths (total lengths).

[0298] Here, the path pattern that reflects at the opening H1 and the path pattern that reflects at the opening H1' provide equal propagation lengths. Further, the path pattern that reflects at the opening H2 and the path pattern that reflects at the opening H2' provide equal propagation lengths.

[0299] However, the two sets of equal propagation lengths are not equal to the propagation length of the main path, and thus there is a time difference in the response outputs. Therefore, the response outputs can be easily separated so that noise is not generated.

[0300] As described above, equal total lengths are provided by some of the path patterns that pass through the opening H1 and the opening H2. However, the total lengths provided by the above-described all path patterns are different from the total length of the main path.

[0301] Accordingly, the power peaks (response outputs) of the respective signal transmission path patterns are separated at important points on the time axis (overlap of the power peaks does not occur with respect to the main path). Therefore, Figure 17 The sensor head 20E according to Comparative Example 2 makes it possible to prevent equal measurement distances (total lengths) from being provided by different signal transmission path patterns, and thus reduces measurement errors. This makes it possible to improve the measurement accuracy of the relative permittivity of a medium or the moisture content in a medium.

[0302] <Comparative Example 2>

[0303] Figure 18 The configuration of the sensor head 20R according to Comparative Example 2 is schematically illustrated.

[0304] The sensor head 20R according to Comparative Example 2 has a configuration similar to that of the sensor head of the sensor device 10' described in Comparative Example 1. Figure 5 The configuration of the sensor head of the sensor device 10' described in Comparative Example 1 is similar to that of the sensor head of the sensor device 10 described in Embodiment 1.

[0305] In other words, in the sensor head 20R, the transmission probe 21 and the reception probe 22 have equal probe lengths, and are each arranged parallel to the Z-axis direction. The opening H1 and the opening H1' face each other at a certain distance from each other in the Y-axis direction, and the opening H2 and the opening H2' face each other at the same distance from each other in the Y-axis direction.

[0306] As Figure 18As shown in the figure, assume that the (signal transmission) path from the base end of the transmission probe 21 to the opening H2 is path 1, the path from the opening H2 to the opening H1 is path 2, and the path from the base end of the reception probe 22 to the opening H2' is path 3.

[0307] Further, assume that the path from the opening H2' to the opening H1' is path 4, the (spatial) path from the opening H2 to the opening H2' is path 5, and the (spatial) path from the opening H1 to the opening H1' is path 6. Here, path 1 = path 3, path 2 = path 4, and path 5 = path 6.

[0308] Consider the case where the signal F is transmitted from the transmission probe 21 to the reception probe 22 through the opening H2.

[0309] The main path to obtain the response output is "path 1→path 5→path 3". In this case, the total (path) length is obtained by "path 1 x 2 + path 5 x 1". Another path is "path 1→path 2→path 2→path 5→path 3 (reflected at opening H1)". In this case, the total length is obtained by "path 1 x 2 + path 2 x 2 + path 5 x 1".

[0310] Another path is "path 1→path 5→path 4→path 4→path 3 (reflected at opening H1')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 2 + path 5 x 1". Another path is "path 1→path 2→path 2→path 5→path 4→path 4→path 3 (reflected at openings H1 and H1')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 5 x 1".

[0311] Next, consider the case where the signal F is transmitted from the transmission probe 21 to the reception probe 22 through the opening H1.

[0312] The main path to obtain the response output is "path 1→path 2→path 6→path 4→path 3". In this case, the total (path) length is obtained by "path 1 x 2 + path 2 x 2 + path 5 x 1". Another path is "path 1→path 2→path 2→path 2→path 6→path 4→path 3 (reflected at opening H2)". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 5 x 1".

[0313] There is also a path of "path 1→ path 2→ path 6→ path 4→ path 4→ path 4→ path 3 (reflected at opening H2')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 5 x 1". There is also a path of "path 1→ path 2→ path 2→ path 2→ path 6→ path 4→ path 4→ path 4→ path 3 (reflected at opening H2 and opening H2')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 5 + path 5 x 1".

[0314] As shown in FIG. 1, Figure 18 When openings H2 and H2' are provided in a case where the transmission probe 21 and the reception probe 22 are arranged parallel to each other, and "path 1 = path 3", "path 2 = path 4", and "path 5 = path 6" are satisfied, the path pattern reflected at opening H1 and the path pattern reflected at opening H1' provide equal propagation lengths. In addition, the path pattern reflected at opening H2 and the path pattern reflected at opening H2' provide equal propagation lengths.

[0315] At this time, the equal propagation lengths provided when reflected at openings H1 and H1' are equal to the propagation length of the main path. This results in a measurement error.

[0316] (When there are three openings)

[0317] <Sixth Embodiment>

[0318] Figure 19 The configuration of the sensor device 10F according to the sixth embodiment of the present technology is schematically illustrated.

[0319] The sensor device 10F of the present embodiment includes a sensor head 20F and a measurement unit 30. In the following description, structural elements different from those of the first embodiment are mainly described. Structural elements similar to those of the first embodiment are indicated by reference numerals similar to those used in the first embodiment, and the description of the above-described structural elements is omitted or simplified.

[0320] The sensor head 20F of the present embodiment is different from those of the above-described first to fifth embodiments in that the transmission probe 21 includes an opening H3 serving as a third transmission micro-antenna portion, and the reception probe 22 includes an opening H3' serving as a third reception micro-antenna portion.

[0321] In the present embodiment, the transmitting probe 21 is arranged parallel to the Z-axis direction, and includes a folded portion 42 that reversely orients the tip 23 of the transmitting probe 21 in the direction of the measurement unit 30. The folded portion 42 reversely orients the transmitting probe 21 by inverting the transmitting probe 21 at an angle greater than 180 degrees, so that the portion of the transmitting probe 21 from the folded portion 42 to the tip 23 is not parallel to the portion of the transmitting probe 21 from the base end to the folded portion 42. The angle at which the portion from the folded portion 42 to the tip 23 is inclined with respect to the Z-axis direction is not particularly limited, and may, for example, be greater than or equal to 5 degrees and less than or equal to 10 degrees.

[0322] An opening H1 is provided at the folded portion 42, and an opening H2 is provided at an intermediate position between the folded portion 42 and the tip 23 of the transmitting probe 21. An opening H3 is provided at the tip of the transmitting probe 21.

[0323] The receiving probe 22 is arranged parallel to the Z-axis direction, and has a probe length equal to the length from the base end of the transmitting probe 21 to the folded portion 42. An opening H1' is provided at the tip 23 of the receiving probe 22, and an opening H2' is provided at an intermediate position between the base end and the tip 23 of the receiving probe 22. An opening H3' is provided at an intermediate position between the base end and the tip 23 of the receiving probe 22.

[0324] The opening H1' of the receiving probe 22 faces the opening H1 of the transmitting probe 21 at a predetermined distance in the Y-axis direction from the opening H1 of the transmitting probe 21, and the opening H2' of the receiving probe 22 faces the opening H2 of the transmitting probe at a distance greater than the predetermined distance in the Y-axis direction from the opening H2 of the transmitting probe. Furthermore, the opening H3' of the receiving probe 22 faces the opening H3 of the transmitting probe 21 at a distance greater than the distance between the other openings, that is, the distance between the opening H1 and the opening H1' and the distance between the opening H2 and the opening H2', in the Y-axis direction from the opening H3 of the transmitting probe 21.

[0325] The measurement unit 30 generates a measurement signal S1 that further includes information on the electromagnetic wave propagation characteristics in the medium between the opening H3 and the opening H3'. In the present embodiment, the distance between the opening H1 and the opening H1', the distance between the opening H2 and the opening H2', and the distance between the opening H3 and the opening H3' are different from each other. This results in providing an effect similar to that provided by the above-described first embodiment.

[0326] As Figure 19As shown in the figure, assume that the (signal transmission) path from the base end of the transmitting probe 21 to a first predetermined position located before the folding portion and facing the opening H3 is path 1, the path from the first predetermined position to a second predetermined position facing the opening H2 is path 2, and the path from the second predetermined position to the opening Hl is path 3.

[0327] Assume that the path from the opening Hl through the folding portion to the opening H2 is path 7, and the path from the opening H2 to the opening H3 is path 8.

[0328] Assume that the path from the tip (Hl') of the receiving probe 22 to the opening H2' is path 4. Further, assume that the path from the opening H2' to the opening H3' is path 5, and the path from the opening H3' to the base end is path 6. In addition, assume that the path (medium) from the opening Hl to the opening Hl' is path 9, the path (medium) from the opening H2 to the opening H2' is path 10, and the path (medium) from the opening H3 to the opening H3' is path 11. Here, path 1 = path 6, path 2 = path 5, path 3 = path 4, and path 9 ≠ path 10 ≠ path 11.

[0329] Consider the case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H3.

[0330] The main path to obtain the response output is "path 1 → path 2 → path 3 → path 7 → path 8 → path 11 → path 6". In this case, the total (path) length is obtained by "path 1 x 2 + path 2 x 1 + path 3 x 1 + path 7 x 1 + path 8 x 1 + path 11 x 1". Another path is "path 1 → path 2 → path 3 → path 7 → path 8 → path 11 → path 5 → path 5 → path 6 (reflected at the opening H2')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 3 + path 3 x 1 + path 7 x 1 + path 8 x 1 + path 11 x 1". Yet another path is "path 1 → path 2 → path 3 → path 7 → path 8 → path 11 → path 5 → path 4 → path 4 → path 5 → path 6 (reflected at the opening Hl')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 3 + path 3 x 1 + path 7 x 3 + path 8 x 1 + path 11 x 1".

[0331] There is also a path of "Path 1→Path 2→Path 3→Path 7→Path 8→Path 8→Path 8→Path 11→Path 6 (reflecting at opening H2)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 1 + Path 3 x 1 + Path 7 x 1 + Path 8 x 3 + Path 11 x 1". There is also a path of "Path 1→Path 2→Path 3→Path 7→Path 8→Path 8→Path 7→Path 7→Path 8→Path 11→Path 6 (reflecting at opening H1)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 1 + Path 3 x 1 + Path 7 x 3 + Path 8 x 3 + Path 11 x 1".

[0332] Further, there is a mode of reflecting at Path 7 and Path 8, and then reflecting at Path 5 and Path 4. However, the total length provided by this mode is greatly different from the total length of the main path. Therefore, the description of the above mode is omitted.

[0333] Next, a case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H2 is considered.

[0334] The main path to obtain the highest (response) power output is "Path 1→Path 2→Path 3→Path 7→Path 10→Path 5→Path 6". In this case, the total (path) length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 1 + Path 7 x 1 + Path 10 x 1". Another path is "Path 1→Path 2→Path 3→Path 7→Path 10→Path 4→Path 4→Path 5→Path 6 (reflecting at opening H1'). In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 3 + Path 7 x 1 + Path 10 x 1".

[0335] There is also a path of "Path 1→Path 2→Path 3→Path 7→Path 7→Path 7→Path 10→Path 5→Path 6 (reflecting at opening H3)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 1 + Path 7 x 3 + Path 10 x 1 + Path 8 x 2". There is also a path of "Path 1→Path 2→Path 3→Path 7→Path 8→Path 8→Path 10→Path 5→Path 6 (reflecting at opening H1)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 1 + Path 7 x 1 + Path 10 x 1 + Path 8 x 2".

[0336] There is also a path of "Path 1→Path 2→Path 3→Path 7→Path 10→Path 5→Path 5→Path 5→Path 6 (reflecting at opening H3')". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 7 x 1 + Path 10 x 1 + Path 8 x 2".

[0337] Another path is "Path 1 → Path 2 → Path 3 → Path 7 → Path 8 → Path 8 → Path 10 → Path 4 → Path 4 → Path 5 → Path 6 (reflected at openings H1 and H1')". In this case, the total length is obtained by "Path 1×2 + Path 2×2 + Path 3×3 + Path 7×1 + Path 10×1 + Path 8×2". Another path is "Path 1 → Path 2 → Path 3 → Path 7 → Path 7 → Path 7 → Path 10 → Path 4 → Path 4 → Path 5 → Path 6 (reflected at openings H3 and H1')". In this case, the total length is obtained by "Path 1×2 + Path 2×2 + Path 3×3 + Path 7×3 + Path 10×1 + Path 8×2".

[0338] Next, consider the case where signal F is transmitted from transmitting probe 21 to receiving probe 22 through opening H1.

[0339] The main path used to obtain the response output is "Path 1 → Path 2 → Path 3 → Path 9 → Path 4 → Path 5 → Path 6". In this case, the total (path) length is obtained by "Path 1 × 2 + Path 2 × 2 + Path 3 × 2 + Path 9 × 1". Another path is "Path 1 → Path 2 → Path 3 → Path 7 → Path 7 → Path 9 → Path 4 → Path 5 → Path 6 (reflection at opening H2). In this case, the total length is obtained by "Path 1 × 2 + Path 2 × 2 + Path 3 × 2 + Path 9 × 1 + Path 7 × 2".

[0340] Another path is "Path 1 → Path 2 → Path 3 → Path 7 → Path 8 → Path 8 → Path 7 → Path 9 → Path 4 → Path 5 → Path 6 (reflected at opening H3)". In this case, the total length is obtained by "Path 1×2 + Path 2×2 + Path 3×2 + Path 9×1 + Path 7×2 + Path 8×2". Another path is "Path 1 → Path 2 → Path 3 → Path 9 → Path 4 → Path 4 → Path 4 → Path 5 → Path 6 (reflected at opening H2')". In this case, the total length is obtained by "Path 1×2 + Path 2×2 + Path 3×3 + Path 9×1".

[0341] Another path is "Path 1 → Path 2 → Path 3 → Path 9 → Path 4 → Path 5 → Path 5 → Path 4 → Path 4 → Path 5 → Path 6 (reflected at opening H3')". In this case, the total length is obtained by "Path 1×2 + Path 2×4 + Path 3×3 + Path 9×1". Another path is "Path 1 → Path 2 → Path 3 → Path 7 → Path 7 → Path 9 → Path 4 → Path 4 → Path 4 → Path 5 → Path 6 (reflected at openings H2 and H2')". In this case, the total length is obtained by "Path 1×2 + Path 2×2 + Path 3×4 + Path 9×1 + Path 7×2".

[0342] In addition, there exists a path pattern where the signal travels forward after being reflected from openings H3 and H3'. However, the total length provided by this path pattern differs significantly from the total length of the main path. Therefore, a description of the aforementioned path pattern is omitted.

[0343] like Figure 19 As shown, when the coaxial cable located before the fold of the transmitting probe 21 is tilted at a predetermined angle relative to the coaxial cable located after the fold of the transmitting probe 21 (so that these coaxial cables are arranged asymmetrically), and the conditions of "path 1 = path 6", "path 2 = path 5", "path 3 = path 4" and "path 9 ≠ path 10 ≠ path 11" are met, and the above six openings H1 to H3' are provided in the transmitting probe 21 and the receiving probe 22, none of the above path patterns provide equal propagation lengths (total lengths).

[0344] In addition, there exists a path pattern where the signal enters the receiver from the transmitting side and then returns to the transmitting side. However, the total length provided by this path pattern differs significantly from the total length of the main path. Therefore, a description of the aforementioned path patterns is omitted.

[0345] As stated above, none of the path patterns through openings H1, H2, and H3 provide an equal total length. In other words, the total lengths provided by all the aforementioned signal transmission patterns are different.

[0346] Accordingly, the power peaks (response outputs) relative to the corresponding signal transmission path modes are separated (non-overlapping) on ​​the time axis. Therefore, Figure 19 The 20F sensor head prevents different signal transmission path modes from providing equal measurement distances (total length), and thus reduces measurement errors. This improves the accuracy of measurements of the relative permittivity of the medium or the moisture content in the medium.

[0347] <Seventh Implementation Method>

[0348] Figure 20 The schematic diagram illustrates the structure of the sensor device 10G according to the seventh embodiment of the present technology.

[0349] The sensor device 10G of this embodiment includes a sensor head 20G and a measurement unit 30. In the following description, structural elements that differ from those of the first embodiment are primarily described. Structural elements similar to those of the first embodiment are indicated by reference numerals similar to those used in the first embodiment, and descriptions of these structural elements are omitted or simplified.

[0350] The difference between this embodiment and the sixth embodiment is that the transmitting probe 21 and the receiving probe 22 have equal probe lengths and are each arranged to be tilted relative to the Z-axis direction, such that the corresponding ends 23 of the transmitting probe 21 and the receiving probe 22 are close to each other. The angle of tilt of each of the probes 21 and 22 relative to the Z-axis direction is, for example, greater than or equal to 5 degrees and less than or equal to 10 degrees.

[0351] The opening H1' of the receiving probe 22 faces the opening H1 of the transmitting probe 21 at a predetermined distance in the Y-axis direction, and the opening H2' of the receiving probe 22 faces the opening H2 of the transmitting probe 21 at a distance greater than the predetermined distance in the Y-axis direction. Furthermore, the opening H3' of the receiving probe 22 faces the opening H3 of the transmitting probe 21 at a distance greater than the distances between other openings (i.e., the distance between opening H1 and opening H1' and the distance between opening H2 and opening H2') in the Y-axis direction. The ratio of the distance between the base of the receiving probe 22 and opening H3', the distance between opening H3' and opening H2', and the distance between opening H2' and opening H1' is not particularly limited, and is, for example, 4:3:3.

[0352] like Figure 20 As shown, assume that the (signal transmission) path from the base of the transmitting probe 21 to the opening H3 is path 1, the path from the opening H3 to the opening H2 is path 2, the path from the opening H2 to the opening H1 is path 3, and the path from the end of the receiving probe 22 (opening H1') to the opening H2' is path 4.

[0353] Furthermore, assume that the path from opening H2' to opening H3' is path 5, the path from opening H3' to the base is path 6, the (spatial) path from opening H1 to opening H1' is path 9, the (spatial) path from opening H2 to opening H2' is path 10, and the (spatial) path from opening H3 to opening H3' is path 11.

[0354] Here, path 9≠ path 10≠ path 11. When the symmetric arrangement is made, "path 1 = path 6", "path 2 = path 5", and "path 3 = path 4" are satisfied, whereas when the asymmetric arrangement is made, "path 1 ≠ path 6", "path 2 ≠ path 5", and "path 3 ≠ path 4" are satisfied.

[0355] Consider the case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H3.

[0356] The main path to obtain a response output is "path 1→ path 2→ path 3→ path 3→ path 2→ path 11→ path 6". In this case, the total (path) length is obtained by "path 1 x 2 + path 2 x 2 + path 3 x 2 + path 11 x 1". Another path is "path 1→ path 2→ path 3→ path 3→ path 2→ path 11→ path 5→ path 5→ path 6 (reflected at the opening H2')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 3 x 2 + path 11 x 1". Still another path is "path 1→ path 2→ path 3→ path 3→ path 2→ path 11→ path 5→ path 4→ path 4→ path 5→ path 6 (reflected at the opening H1')". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 3 x 4 + path 11 x 1".

[0357] Still another path is "path 1→ path 2→ path 3→ path 3→ path 2→ path 2→ path 2→ path 11→ path 6 (reflected at the opening H2)". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 3 x 2 + path 11 x 1". Still another path is "path 1→ path 2→ path 3→ path 3→ path 2→ path 2→ path 3→ path 3→ path 2→ path 11→ path 6 (reflected at the opening H3)". In this case, the total length is obtained by "path 1 x 2 + path 2 x 4 + path 3 x 4 + path 11 x 1".

[0358] Further, there is a mode of reflecting at path 3 and path 2, and then reflecting at path 5 and path 4. However, the total length provided by this mode is greatly different from the total length of the main path. Therefore, the description of this mode is omitted.

[0359] Next, consider the case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H2.

[0360] The main path to obtain a response output is "Path 1→Path 2→Path 3→Path 3→Path 10→Path 5→Path 6". In this case, the total (path) length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 2 + Path 10 x 1". Another path is "Path 1→Path 2→Path 3→Path 3→Path 10→Path 4→Path 4→Path 5→Path 6 (reflected at opening H1)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 4 + Path 10 x 1".

[0361] Another path is "Path 1→Path 2→Path 3→Path 3→Path 3→Path 3→Path 10→Path 5→Path 6 (reflected at opening H3)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 4 + Path 10 x 1". Another path is "Path 1→Path 2→Path 3→Path 3→Path 2→Path 2→Path 10→Path 5→Path 6 (reflected at opening H1)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 2 + Path 10 x 1".

[0362] Another path is "Path 1→Path 2→Path 3→Path 3→Path 10→Path 5→Path 5→Path 5→Path 6 (reflected at opening H3)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 6 + Path 3 x 1 + Path 10 x 1".

[0363] Another path is "Path 1→Path 2→Path 3→Path 3→Path 2→Path 2→Path 10→Path 4→Path 4→Path 5→Path 6 (reflected at openings H1 and H1)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 4 + Path 10 x 1". Another path is "Path 1→Path 2→Path 3→Path 3→Path 3→Path 3→Path 10→Path 4→Path 4→Path 5→Path 6 (reflected at openings H3 and H1)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 6 + Path 10 x 1".

[0364] Next, consider the case where a signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H1.

[0365] The main path used to obtain the response output is "Path 1 → Path 2 → Path 3 → Path 9 → Path 4 → Path 5 → Path 6". In this case, the total (path) length is obtained by "Path 1 × 2 + Path 2 × 2 + Path 3 × 2 + Path 9 × 1". Another path is "Path 1 → Path 2 → Path 3 → Path 3 → Path 3 → Path 9 → Path 4 → Path 5 → Path 6 (reflection at opening H2). In this case, the total length is obtained by "Path 1 × 2 + Path 2 × 2 + Path 3 × 4 + Path 9 × 1".

[0366] Another path is "Path 1 → Path 2 → Path 3 → Path 3 → Path 2 → Path 2 → Path 3 → Path 9 → Path 4 → Path 5 → Path 6 (reflected at opening H1)". In this case, the total length is obtained by "Path 1×2 + Path 2×4 + Path 3×4 + Path 9×1". Another path is "Path 1 → Path 2 → Path 3 → Path 9 → Path 4 → Path 4 → Path 4 → Path 5 → Path 6 (reflected at opening H2')". In this case, the total length is obtained by "Path 1×2 + Path 2×2 + Path 3×3 + Path 9×1".

[0367] Another path is "Path 1 → Path 2 → Path 3 → Path 9 → Path 4 → Path 5 → Path 5 → Path 4 → Path 4 → Path 5 → Path 6 (reflected at opening H3')". In this case, the total length is obtained by "Path 1×2 + Path 2×4 + Path 3×3 + Path 9×1". Another path is "Path 1 → Path 2 → Path 3 → Path 3 → Path 3 → Path 9 → Path 4 → Path 4 → Path 4 → Path 5 → Path 6 (reflected at openings H2 and H2')". In this case, the total length is obtained by "Path 1×2 + Path 2×2 + Path 3×6 + Path 9×1".

[0368] Furthermore, there exists a path pattern where the signal travels forward after being reflected from openings H1 and H3'. However, the total length provided by this pattern differs significantly from the total length of the main path. Therefore, a description of this pattern is omitted.

[0369] Additionally, there is a path pattern where the signal enters the receiver from the transmitter and then returns to the transmitter. However, the total length provided by this pattern differs significantly from the total length of the main path. Therefore, a description of this pattern is omitted.

[0370] like Figure 20 As shown, when the transmitting probe 21 and the receiving probe 22 are each arranged to be tilted at a predetermined angle relative to the Z-axis direction, and when the openings H3 and H3' are set up to satisfy “path 1 = path 6”, “path 2 = path 5” and “path 3 = path 4”, some of the path patterns mentioned above do not provide equal propagation lengths (total lengths).

[0371] Here, the path pattern that passes through the opening H3 and is reflected at the opening H2 and the path pattern that passes through the opening H3 and is reflected at the opening H2 provide equal propagation lengths. Further, the path pattern that passes through the opening H3 and is reflected at the opening H3 and the path pattern that passes through the opening H3 and is reflected at the opening H1' provide equal propagation lengths.

[0372] The path pattern that passes through the opening H2 and is reflected at the opening H3 and the path pattern that passes through the opening H2 and is reflected at the opening H1' provide equal propagation lengths.

[0373] However, the three sets of equal propagation lengths are not equal to the propagation length of the main path, and thus there is a time difference in the response outputs. Therefore, the response outputs can be easily separated, and this makes it possible to prevent noise from being generated.

[0374] Alternatively, when the opening H3 and the opening H3' are set under the condition that the transmission probe 21 (or the reception probe 22) is arranged to be inclined at a predetermined angle with respect to the reception probe 22 (or the transmission probe 21) and the conditions "path 1 ≠ path 6", "path 2 ≠ path 5", and "path 3 ≠ path 4" are satisfied, none of the above-described path patterns provide equal propagation lengths (total lengths). In this case, a path pattern similar to that of the third embodiment is provided. Therefore, the description of the above-described path patterns is omitted.

[0375] Accordingly, the power peaks (response outputs) with respect to the respective signal transmission path patterns are separated (not overlapped) on the time axis. Therefore, Figure 20 The sensor head 20G makes it possible to prevent equal measurement distances (total lengths) from being provided by different signal transmission path patterns, and thus reduces measurement errors. This makes it possible to improve the measurement accuracy of the relative permittivity of a medium or the moisture content in a medium.

[0376] <Comparative Example 3>

[0377] Figure 21 The configuration of the sensor head 20R' according to Comparative Example 3 is schematically illustrated.

[0378] In the sensor head 20R' according to Comparative Example 3, the transmission probe 21 is arranged parallel to the Z-axis direction. The transmission probe 21 includes a folded portion 42, and the portion from the folded portion 42 to the tip 23 is formed parallel to the Z-axis direction. The opening H1 is provided to the folded portion 42, the opening H2 is provided to the tip 23, and the opening H3 is provided to an intermediate position between the folded portion 42 and the tip 23.

[0379] In the sensor head 20R', the receiving probe 22 is arranged in parallel to the Z-axis direction, and has a probe length equal to the length from the base end of the transmitting probe 21 to the folding portion 42. The opening H1' is provided at the tip end 23 of the receiving probe 22, and faces the opening H1 of the transmitting probe 21 at a predetermined distance in the Y-axis direction from the opening H1 of the transmitting probe 21. The opening H2' is provided between the base end and the tip end 23 of the receiving probe 22, and faces the opening H2 of the transmitting probe 21 at the predetermined distance in the Y-axis direction from the opening H2 of the transmitting probe 21. The opening H3' is provided between the base end and the tip end 23 of the receiving probe 22, and faces the opening H3 of the transmitting probe 21 at the predetermined distance in the Y-axis direction from the opening H3 of the transmitting probe 21.

[0380] In this example, as shown in FIG. 6, it is assumed that the (signal transmission) path from the base end of the transmitting probe 21 to a first predetermined position located before the folding portion and facing the opening H3 is path 1, the path from the first predetermined position to a second predetermined position facing the opening H2 is path 2, and the path from the second predetermined position to the opening H1 is path 3. Figure 21

[0381] Further, it is assumed that the path from the opening H1 to the opening H2 through the folding portion is path 7, and the path from the opening H2 to the opening H3 is path 8.

[0382] It is assumed that the path from the tip end (H1') of the receiving probe 22 to the opening H2' is path 4, the path from the opening H2' to the opening H3' is path 5, and the path from the opening H3' to the base end is path 6. Further, it is assumed that the path (medium) from the opening H1 to the opening H1' is path 9, the path (medium) from the opening H2 to the opening H2' is path 10, and the path (medium) from the opening H3 to the opening H3' is path 11.

[0383] Here, path 1 = path 6, path 2 = path 5 = path 8, path 3 = path 4 ≠ path 7, and path 10 = path 11 ≠ path 9.

[0384] Consider a case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H3.

[0385] ​The main path to obtain a response output is "Path 1→ Path 2→ Path 3→ Path 7→ Path 8→ Path 11→ Path 6". In this case, the total (path) length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 1 + Path 7 x 1 + Path 10 x 1". Another path is "Path 1→ Path 2→ Path 3→ Path 7→ Path 8→ Path 11→ Path 5→ Path 5→ Path 6 (reflected at opening H2')". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 1 + Path 7 x 1 + Path 10 x 1". Still another path is "Path 1→ Path 2→ Path 3→ Path 7→ Path 8→ Path 11→ Path 5→ Path 4→ Path 4→ Path 5→ Path 6 (reflected at opening H1')". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 1 + Path 7 x 3 + Path 10 x 1".

[0386] Still another path is "Path 1→ Path 2→ Path 3→ Path 7→ Path 8→ Path 8→ Path 8→ Path 11→ Path 6 (reflected at opening H2)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 1 + Path 7 x 1 + Path 10 x 1". Still another path is "Path 1→ Path 2→ Path 3→ Path 7→ Path 8→ Path 8→ Path 7→ Path 7→ Path 8→ Path 11→ Path 6 (reflected at opening H1)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 1 + Path 7 x 3 + Path 10 x 1".

[0387] Further, there is a mode of reflecting at Path 7 and Path 8, and then reflecting at Path 5 and Path 4. However, the total length provided by this mode is greatly different from the total length of the main path. Therefore, the description of this mode is omitted.

[0388] Next, a case where a signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H2 is considered.

[0389] The main path to obtain a response output is "Path 1→ Path 2→ Path 3→ Path 7→ Path 10→ Path 5→ Path 6". In this case, the total (path) length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 1 + Path 7 x 1 + Path 10 x 1". Another path is "Path 1→ Path 2→ Path 3→ Path 7→ Path 10→ Path 4→ Path 4→ Path 5→ Path 6 (reflected at opening H1')". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 3 + Path 7 x 1 + Path 10 x 1".

[0390] Another path is "Path 1→Path 2→Path 3→Path 7→Path 7→Path 7→Path 10→Path 5→Path 6 (reflecting at opening H3)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 1 + Path 7 x 3 + Path 10 x 1". Another path is "Path 1→Path 2→Path 3→Path 7→Path 8→Path 8→Path 10→Path 5→Path 6 (reflecting at opening H3)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 1 + Path 7 x 1 + Path 10 x 1".

[0391] Another path is "Path 1→Path 2→Path 3→Path 7→Path 10→Path 5→Path 5→Path 5→Path 6 (reflecting at opening H3)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 6 + Path 7 x 1 + Path 10 x 1".

[0392] Another path is "Path 1→Path 2→Path 3→Path 7→Path 8→Path 8→Path 10→Path 4→Path 4→Path 5→Path 6 (reflecting at opening H3 and opening H1)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 3 + Path 7 x 1 + Path 10 x 1". Another path is "Path 1→Path 2→Path 3→Path 7→Path 7→Path 7→Path 10→Path 4→Path 4→Path 5→Path 6 (reflecting at opening H1 and opening H1)". In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 4 + Path 3 x 3 + Path 7 x 3 + Path 10 x 1".

[0393] Next, consider the case where the signal F is transmitted from the transmitting probe 21 to the receiving probe 22 through the opening H1.

[0394] The main path to obtain the response output is "Path 1→Path 2→Path 3→Path 9→Path 4→Path 5→Path 6". In this case, the total (path) length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 2 + Path 9 x 1". Another path is "Path 1→Path 2→Path 3→Path 7→Path 7→Path 9→Path 4→Path 5→Path 6 (reflecting at opening H2). In this case, the total length is obtained by "Path 1 x 2 + Path 2 x 2 + Path 3 x 2 + Path 9 x 1 + Path 7 x 2".

[0395] There is also a path pattern in which the signal travels forward after being reflected from the opening H3 and the opening H3'. However, the total length provided by this pattern is quite different from the total length of the main path. Therefore, the description of this pattern is omitted.

[0396] There is also a path pattern in which the signal travels forward after being reflected from the opening H3 and the opening H3'. However, the total length provided by this pattern is quite different from the total length of the main path. Therefore, the description of this pattern is omitted.

[0397] In addition, there is a path pattern in which the signal enters the receiving side from the transmitting side and then returns to the transmitting side. However, the total length provided by this pattern is quite different from the total length of the main path. Therefore, the description of this pattern is omitted.

[0398] In addition, there is a path pattern in which the signal enters the receiving side from the transmitting side and then returns to the transmitting side. However, the total length provided by this pattern is quite different from the total length of the main path. Therefore, the description of this pattern is omitted.

[0399] As shown in FIG. 6, when the six openings H1 to H3' are provided at the transmitting probe 21 and the receiving probe 22 under the condition that the transmitting probe 21 and the receiving probe 22 are arranged in parallel to each other before and after the folded portions thereof, and that the conditions of "path 1 = path 6", "path 2 = path 5 = path 8", "path 3 = path 4 ≠ path 7", and "path 10 = path 11 ≠ path 9" are satisfied, the main path through the opening H1 and the main path through the opening H2 have equal propagation lengths, which causes a measurement error. Figure 21 As described above, in the first to seventh embodiments, the transmitting probe 21 and the receiving probe 22 are configured so that the main path and the paths other than the main path have different total lengths.

[0400]

[0401] ​There are two openings in the first to fifth embodiments, and there are three openings in the sixth and seventh embodiments. Although the description of the probes 21 and 22 is omitted, the probes 21 and 22 can each include four or more openings each serving as a micro antenna section.

[0402] In the respective embodiments, the path length difference between the signal transmission paths of the plurality of signal transmission paths each passing through the openings (H1 to H3') is greater than or equal to a predetermined effective wavelength (2.06 cm). In the third, fourth, sixth, and seventh embodiments, the probes 21 and 22 are each arranged to be inclined with respect to the Z-axis direction so that the path length difference between the signal transmission paths is greater than or equal to the predetermined effective wavelength.

[0403] <Modification>

[0404] Embodiments of the present technology have been described above. However, the present technology is not limited to the above-described embodiments, and various modifications can be made to the above-described embodiments.

[0405] For example, in the above-described embodiments, an example in which the present technology is applied to measurement of the water content in soil in which crops are to grow has been described. However, the present technology is not limited thereto, and can also be applied to research and measurement of, for example, the concentration of different substances (such as fertilizers) having known relative permittivities.

[0406] The measurement target medium is not limited to soil, and can be a substance other than soil, such as livestock feed.

[0407] The water content measuring device 100 is configured to calculate the relative permittivity using the electromagnetic wave propagation characteristics in the medium, and to calculate the water content in the medium using the relative permittivity. The water content measuring device 100 can be configured to directly calculate the water content in the medium using the obtained electromagnetic wave propagation characteristics, not limited thereto. For example, when the medium includes a relatively simple system, a correspondence table of the propagation characteristics of the electromagnetic wave and the water content in the medium can be established, and thus the water content in the medium can be obtained directly using the electromagnetic wave propagation characteristics by referring to the correspondence table.

[0408] Furthermore, the sensor head can further include a temperature detector and / or an electrical conductivity detector.

[0409] The temperature detector can detect the temperature of the medium. For example, any temperature sensor such as a thermocouple or a thermistor can be employed as the temperature detector. For example, the temperature detector is disposed in the vicinity of the micro antenna sections 221 and 222 for reception of the probe 22.

[0410] The conductivity detector can detect the conductivity of the medium. For example, a suitable conductivity or resistivity sensor such as a two-wire or four-wire sensor can be employed as the conductivity detector. The conductivity detector is provided in the vicinity of the micro antenna section 211 and the micro antenna section 212, for example, for transmission of the probe 21.

[0411] It is known that the relative permittivity of a medium has a certain correlation with the temperature or the conductivity of the medium. According to this example, not only the electromagnetic wave propagation characteristics in the medium can be acquired, but also information about the temperature and the conductivity of the medium can be acquired. Therefore, the calculated value of the relative permittivity of the medium or the volume water content in the medium can be corrected based on the acquired temperature information or conductivity information. This makes it possible to further improve the measurement accuracy.

[0412] As an alternative or in addition to the temperature detector and the conductivity detector, a pH detector that can measure the pH value of the medium can be provided to the sensor head.

[0413] Further, in the above-described embodiments, an example has been described in which the signal processing unit 50 includes a single information processing device. Not being limited thereto, the signal processing unit 50 can include a computer system in which a plurality of computers operate in cooperation with each other.

[0414] Note that the present technology can also take the following configuration.

[0415] (1) A sensor device including:

[0416] a sensor head including a first probe including a first transmission micro antenna section and a second transmission micro antenna section, and a second probe including a first reception micro antenna section and a second reception micro antenna section, the second probe being arranged at a predetermined distance from the first probe; and

[0417] a measurement unit including a controller that generates a measurement signal including information about electromagnetic wave propagation characteristics in a medium between the first transmission micro antenna section and the first reception micro antenna section, and information about electromagnetic wave propagation characteristics in a medium between the second transmission micro antenna section and the second reception micro antenna section, wherein

[0418] the first probe and the second probe have different probe lengths, or distances between the first transmission micro antenna section and the first reception micro antenna section and between the second transmission micro antenna section and the second reception micro antenna section are different from each other.

[0419] (2) The sensor device according to (1), wherein

[0420] The first probe and the second probe each include a coaxial cable including a core wire portion and a shield portion, and

[0421] The first transmission micro antenna portion, the second transmission micro antenna portion, the first reception micro antenna portion, and the second reception micro antenna portion each include an opening provided at a portion of the shield portion.

[0422] (3) The sensor device according to (1) or (2), wherein

[0423] The second probe includes a bent portion provided between the first reception micro antenna portion and the second reception micro antenna portion.

[0424] (4) The sensor device according to (1) or (2), wherein

[0425] The first probe includes a folded portion,

[0426] The first transmission micro antenna portion is provided at the folded portion, and

[0427] The second transmission micro antenna portion is provided at a tip of the first probe.

[0428] (5) The sensor device according to any one of (1) to (4), wherein

[0429] The sensor head further includes a support that supports the first probe and the second probe, and

[0430] The first probe is supported by the support in a state that is not parallel to the second probe.

[0431] (6) The sensor device according to any one of (1) to (5), wherein

[0432] The first probe includes a third transmission micro antenna portion,

[0433] The second probe includes a third reception micro antenna portion, and

[0434] The measurement unit generates a measurement signal further including information on an electromagnetic wave propagation characteristic in a medium between the third transmission micro antenna portion and the third reception micro antenna portion.

[0435] (7) The sensor device according to any one of (1) to (6), wherein

[0436] The sensor head includes a first signal transmission path passing between the first transmission micro antenna portion and the first reception micro antenna portion, or between the first transmission micro antenna portion and the second reception micro antenna portion, and a second signal transmission path passing between the second transmission micro antenna portion and the first reception micro antenna portion, or between the second transmission micro antenna portion and the second reception micro antenna portion, and

[0437] Each of a path length difference between the first signal transmission paths, a path length difference between the second signal transmission paths, and a path length difference between the first signal transmission paths and the second signal transmission paths is greater than or equal to a predetermined effective wavelength.

[0438] (8) The sensor device according to (7), in which

[0439] The predetermined effective wavelength is greater than or equal to 2.06 cm.

[0440] (9) The sensor device according to any one of (1) to (8), in which

[0441] Arrangements of the first transmission micro antenna portion and the second transmission micro antenna portion are asymmetric with respect to arrangements of the first reception micro antenna portion and the second reception micro antenna portion with respect to each other.

[0442] (10) A water content measuring device including:

[0443] A sensor head including a first probe including a first transmission micro antenna portion and a second transmission micro antenna portion, and a second probe including a first reception micro antenna portion and a second reception micro antenna portion, the second probe being arranged at a predetermined distance from the first probe;

[0444] A measurement unit including a controller generating a measurement signal including information on electromagnetic wave propagation characteristics in a medium between the first transmission micro antenna portion and the first reception micro antenna portion, and information on electromagnetic wave propagation characteristics between the second transmission micro antenna portion and the second reception micro antenna portion; and

[0445] A signal processing unit measuring a water content in the medium based on the measurement signal, in which

[0446] The first probe and the second probe have different probe lengths, or distances between the first transmission micro antenna portion and the first reception micro antenna portion and between the second transmission micro antenna portion and the second reception micro antenna portion are different from each other.

[0447] (11) The water content measuring apparatus according to (10), wherein

[0448] The signal processing unit includes:

[0449] a delay time calculator that calculates an electromagnetic wave propagation delay time between the first probe and the second probe based on the measurement signal,

[0450] a relative dielectric constant calculator that calculates a relative dielectric constant of the medium based on the propagation delay time, and

[0451] a water content calculator that calculates a water content in the medium based on the relative dielectric constant.

[0452] Reference Signs

[0453] 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G sensor device

[0454] 20, 20A, 20B, 20C, 20D, 20E, 20F, 20G sensor head

[0455] 21 transmitting probe

[0456] 22 receiving probe

[0457] 23 tip

[0458] 30 measuring unit

[0459] 31 signal generator

[0460] 50 signal processing unit

[0461] 51 delay time calculator

[0462] 52 relative dielectric constant calculator

[0463] 53 water content calculator

[0464] 100 water content measuring apparatus

[0465] 210, 211, 212, 220, 221, 222 micro antenna portion

[0466] 310 controller

[0467] H1, H1', H2, H2', H3, H3' opening

Claims

1. A sensor device comprising: a sensor head including a first probe and a second probe arranged at a predetermined distance from the first probe, the first probe having a first transmitting micro antenna portion and a second transmitting micro antenna portion, the second probe having a first receiving micro antenna portion and a second receiving micro antenna portion; and a measurement unit having a controller that generates a measurement signal including information on electromagnetic wave propagation characteristics in a medium between the first transmitting micro antenna portion and the first receiving micro antenna portion and information on electromagnetic wave propagation characteristics in a medium between the second transmitting micro antenna portion and the second receiving micro antenna portion, wherein a probe length of the first probe and the second probe are different from each other, or a distance between the first transmitting micro antenna portion and the first receiving micro antenna portion and a distance between the second transmitting micro antenna portion and the second receiving micro antenna portion are different from each other, and the second probe has a bent portion provided between the first receiving micro antenna portion and the second receiving micro antenna portion.

2. The sensor device according to claim 1, wherein the first probe and the second probe are each constituted by a coaxial cable including a core portion and a shield portion, and the first transmitting micro antenna portion, the second transmitting micro antenna portion, the first receiving micro antenna portion, and the second receiving micro antenna portion each contain an opening provided at a portion of the shield portion.

3. The sensor device according to claim 1, wherein the sensor head further has a support that supports the first probe and the second probe, and the first probe is supported by the support in a state not parallel to the second probe.

4. The sensor device according to claim 1, wherein the first probe includes a third transmitting micro antenna portion, the second probe includes a third receiving micro antenna portion, and the measurement unit generates a measurement signal further including information on electromagnetic wave propagation characteristics in a medium between the third transmitting micro antenna portion and the third receiving micro antenna portion.

5. The sensor device according to claim 1, wherein the first transmitting micro antenna portion and the second transmitting micro antenna portion and the first receiving micro antenna portion and the second receiving micro antenna portion are asymmetrically arranged with respect to each other.

6. A sensor device comprising: a sensor head including a first probe and a second probe arranged at a predetermined distance from the first probe, the first probe having a first transmitting micro antenna portion and a second transmitting micro antenna portion, the second probe having a first receiving micro antenna portion and a second receiving micro antenna portion; and a measurement unit having a controller that generates a measurement signal including information on electromagnetic wave propagation characteristics in a medium between the first transmitting micro antenna portion and the first receiving micro antenna portion and information on electromagnetic wave propagation characteristics in a medium between the second transmitting micro antenna portion and the second receiving micro antenna portion, wherein a probe length of the first probe and the second probe are different from each other, or a distance between the first transmitting micro antenna portion and the first receiving micro antenna portion and a distance between the second transmitting micro antenna portion and the second receiving micro antenna portion are different from each other, and the second probe has a bent portion provided between the first receiving micro antenna portion and the second receiving micro antenna portion. a probe length of the first probe and the second probe is different from each other, or a distance between the first transmission micro antenna portion and the first reception micro antenna portion and a distance between the second transmission micro antenna portion and the second reception micro antenna portion are different from each other, the first probe has a folded portion, the first transmission micro antenna portion is provided at the folded portion, and the second transmission micro antenna portion is provided at a tip of the first probe.

7. A sensor device comprising: a sensor head including a first probe and a second probe arranged at a predetermined distance from the first probe, the first probe having a first transmission micro antenna portion and a second transmission micro antenna portion, the second probe having a first reception micro antenna portion and a second reception micro antenna portion; and a measurement unit having a controller that generates a measurement signal including information on an electromagnetic wave propagation characteristic in a medium between the first transmission micro antenna portion and the first reception micro antenna portion, and information on an electromagnetic wave propagation characteristic in a medium between the second transmission micro antenna portion and the second reception micro antenna portion, wherein a probe length of the first probe and the second probe is different from each other, or a distance between the first transmission micro antenna portion and the first reception micro antenna portion and a distance between the second transmission micro antenna portion and the second reception micro antenna portion are different from each other, the sensor head includes a first signal transmission path passing between the first transmission micro antenna portion and the first reception micro antenna portion, or between the first transmission micro antenna portion and the second reception micro antenna portion, and a second signal transmission path passing between the second transmission micro antenna portion and the first reception micro antenna portion, or between the second transmission micro antenna portion and the second reception micro antenna portion, and a path length difference between the first signal transmission paths, a path length difference between the second signal transmission paths, and a path length difference between the first signal transmission paths and the second signal transmission paths are each greater than or equal to a predetermined effective wavelength.

8. The sensor device according to claim 7, wherein the predetermined effective wavelength is greater than or equal to 2.06 cm.

9. A moisture content measuring device including: the sensor device according to claim 1, 6, or 7; and a signal processing unit that measures a moisture content in the medium based on the measurement signal.

10. The moisture content measuring device according to claim 9, wherein the signal processing unit includes a delay time calculator that calculates an electromagnetic wave propagation delay time between the first probe and the second probe based on the measurement signal, a relative permittivity calculator that calculates a relative permittivity of the medium based on the propagation delay time, and a moisture content calculator that calculates a moisture content in the medium based on the relative permittivity.

11. The moisture content measuring device according to claim 10, wherein the signal processing unit further includes a temperature sensor that measures a temperature of the medium, and the moisture content calculator calculates the moisture content in the medium based on the relative permittivity and the temperature of the medium.

12. The moisture content measuring device according to claim 11, wherein the temperature sensor is provided in the sensor head.

13. The moisture content measuring device according to claim 10, wherein the signal processing unit further includes a humidity sensor that measures a humidity of the medium, and the moisture content calculator calculates the moisture content in the medium based on the relative permittivity and the humidity of the medium.

14. The moisture content measuring device according to claim 13, wherein the humidity sensor is provided in the sensor head.

15. The moisture content measuring device according to claim 10, wherein the signal processing unit further includes a pressure sensor that measures a pressure of the medium, and the moisture content calculator calculates the moisture content in the medium based on the relative permittivity and the pressure of the medium.

16. The moisture content measuring device according to claim 15, wherein the pressure sensor is provided in the sensor head.

17. The moisture content measuring device according to claim 10, wherein the signal processing unit further includes a flow rate sensor that measures a flow rate of the medium, and the moisture content calculator calculates the moisture content in the medium based on the relative permittivity and the flow rate of the medium.

18. The moisture content measuring device according to claim 17, wherein the flow rate sensor is provided in the sensor head.

19. The moisture content measuring device according to claim 10, wherein the signal processing unit further includes a temperature sensor that measures a temperature of the medium, a humidity sensor that measures a humidity of the medium, a pressure sensor that measures a pressure of the medium, and a flow rate sensor that measures a flow rate of the medium, and the moisture content calculator calculates the moisture content in the medium based on the relative permittivity, the temperature of the medium, the humidity of the medium, the pressure of the medium, and the flow rate of the medium.

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