Waveguide device and detection device

Abstract

To provide a waveguide device capable of achieving sufficient radiation characteristics of an antenna device even when the waveguide device is disposed close to a metal member inside a hole provided in a building, and to provide a detection device.SOLUTION: A waveguide device includes a waveguide part provided inside a hole formed in a wall part of a building, the waveguide part having a bottomed cylindrical shape or a cylindrical shape having openings at both ends, and an antenna device capable of radiating radio waves in an axial direction of the waveguide part is disposed inside the waveguide part in a state where the waveguide part is provided inside the hole.SELECTED DRAWING: Figure 8A

Description

[Technical Field]

[0001] The present disclosure relates to wave directing devices and detection devices. [Background technology]

[0002] Conventionally, there has been a fastening strength detection device characterized by comprising a main body formed in a cylindrical shape through the center of which the shaft of a fastening means can be inserted and which is fastened together with the fastened object by the fastening means, a detection means for detecting the state of distortion of the main body, a transmission unit for wirelessly transmitting the detection value detected by the detection means, a short bar of an appropriate length extending circumferentially around the outer surface of a peripheral wall portion that forms the cylindrical shape of the main body or around an imaginary plane that surrounds the outside of the peripheral wall, and an antenna that is arranged within the outer surface of the peripheral wall portion or the imaginary plane that surrounds the outside of the peripheral wall portion and is formed in a linear or band-like shape with an appropriate length (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-173543 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the antenna of conventional fastening strength detection devices is installed on the peripheral wall, which is the side of the main body, if the antenna is placed close to the metal member, such as when it is installed on top of the metal member inserted into the shaft portion of the fastening means (fastening mechanism), sufficient radiation characteristics may not be obtained and the detected value may not be able to be transmitted wirelessly.

[0005] Furthermore, when the antenna of a conventional fastening strength detection device is placed close to a metal member inside a hole in a building, such as when the antenna is placed on top of a metal member inserted into the shaft of a fastening means (fastening mechanism) inside a hole in a building, sufficient radiation characteristics may not be obtained, and the detected value may not be able to be transmitted wirelessly.

[0006] Therefore, the object is to provide a waveguide device and a detection device that can achieve sufficient radiation characteristics of an antenna device even when placed close to a metal member inside a hole in a building. [Means for solving the problem]

[0007] A waveguide device according to an embodiment of the present disclosure is a waveguide section provided inside a hole formed in the wall of a building, and includes a waveguide section having a cylindrical shape with a bottom or a cylindrical shape with openings at both ends, and with the waveguide section provided inside the hole, an antenna device capable of radiating radio waves in the axial direction of the waveguide section is disposed inside the waveguide section. [Effects of the Invention]

[0008] It is possible to provide a waveguide device and a detection device that can achieve sufficient radiation characteristics of an antenna device even when placed in close proximity to a metal member inside a hole in a building. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating an example of the configuration of a detection unit included in the detection device according to the embodiment. [Figure 2] FIG. 2 is a diagram illustrating a disassembled state of the detection device according to the embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of a configuration of a circuit board unit of the detection device according to the embodiment. [Figure 4A] FIG. 2 is a diagram illustrating an example of a configuration of an upper surface side of a lower wiring substrate of the detection device according to the embodiment. [Figure 4B] FIG. 2 is a diagram illustrating an example of a configuration of a lower surface side of a lower wiring substrate of the detection device according to the embodiment. [Figure 5A] FIG. 2 is a diagram illustrating an example of a configuration of an upper surface side of an upper wiring substrate of the detection device according to the embodiment. [Figure 5B] FIG. 2 is a diagram illustrating an example of a configuration of a lower surface side of an upper wiring substrate of the detection device according to the embodiment. [Figure 6A] FIG. 1 is a diagram illustrating an example of a configuration of a detection device according to an embodiment. [Figure 6B] FIG. 2 is a diagram showing a state in which the detection device according to the embodiment is separated into a detection unit and a wave-guiding device. [Figure 7A] FIG. 10 is a diagram showing an example of a comparative installation structure of a detection unit using a washer. [Figure 7B] FIG. 10 is a diagram showing an example of an installation structure of a detection unit installed in a comparative installation structure. [Figure 7C] 7C is a diagram showing an example of the configuration of a cross section taken along the arrow AA in FIG. 7B. [Figure 8A] 10A and 10B are diagrams illustrating an example of an installation structure of an embodiment of a detection unit. [Figure 8B] 10A and 10B are diagrams illustrating an example of an installation structure of an embodiment of a detection unit. [Figure 8C] 10A and 10B are diagrams illustrating an example of an installation structure of an embodiment of a detection unit. [Figure 9A] 10A and 10B are diagrams illustrating an example of an installation structure of a modified example of the detection unit according to the embodiment. [Figure 9B] 10A and 10B are diagrams illustrating an example of an installation structure of a modified example of the detection unit according to the embodiment. [Figure 9C] 10A and 10B are diagrams illustrating an example of an installation structure of a modified example of the detection unit according to the embodiment. [Figure 9D] FIG. 10 is a diagram illustrating an example of the configuration of a waveguide device according to a modified example of the embodiment. [Figure 10A] FIG. 10 is a diagram illustrating an example of the configuration of a waveguide device according to a modified example of the embodiment. [Figure 10B] FIG. 10 is a diagram illustrating an example of the configuration of a waveguide device according to a modified example of the embodiment. [Figure 10C] FIG. 10 is a diagram illustrating an example of the configuration of a waveguide device according to a modified example of the embodiment. [Figure 11A] The graph shows the characteristics of the gain of the circularly polarized radio wave emitted from the detector in the +Z direction versus the depth d of the hole. [Figure 11B] 10 shows the characteristics of the S11 parameter of the antenna device at the detection section with respect to the depth of the hole. [Figure 11C] 10 shows the characteristics of the bandwidth of the antenna device of the detector with respect to the depth of the hole. [Figure 12] The graph shows the characteristics of the average gain of the circularly polarized radio waves emitted in the +Z direction by the detector with respect to the depth of the hole when the operating frequency of the antenna element is 2.45 GHz. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments to which the wave-guiding device and the detection device of the present disclosure are applied will be described. In the following, the same elements will be denoted by the same reference numerals, and duplicated descriptions may be omitted.

[0011] In the following description, an XYZ coordinate system is defined. The direction parallel to the X axis (X direction), the direction parallel to the Y axis (Y direction), and the direction parallel to the Z axis (Z direction) are perpendicular to one another. Planar view refers to viewing from an XY plane. For ease of explanation, the +Z direction is referred to as the upper side and the −Z direction is referred to as the lower side, but this does not represent a universal vertical relationship. In the following description, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand. The detection device of the embodiment is disk-shaped in plan view. Therefore, in the following description, the radial direction refers to the radial direction of the disk shape of the detection device.

[0012] <Embodiment> <Outline of detection unit 100D> 1 is a diagram showing an example of the configuration of a detection unit 100D included in a detection device of the embodiment. The detection unit 100D is fixed to a structure with a bolt portion of a fastening mechanism inserted into a through-hole 123 of a flexure body 120 housed in a case 110, and the fastening mechanism and a fastened member abut against the lower and upper surfaces of a main body portion of the flexure body 120 that protrudes upward and downward from the case 110. The lower and upper surfaces of the main body portion of the flexure body 120 protrude in the -Z direction and the +Z direction, respectively, beyond the case 110.

[0013] The detection unit 100D detects the axial fastening force applied to the bolt when the fastening mechanism fastens the detection unit 100D to the workpieces. The detection unit 100D outputs a strain detection signal representing the axial fastening force to the outside via wireless communication.

[0014] <Configuration of detection unit 100D> FIG. 2 is a diagram showing an exploded view of the detection unit 100D. The right side of FIG. 2 shows an enlarged view of the strain body 120 and the strain sensor 130. FIG. 3 is a diagram showing an example of the configuration of the circuit board unit 140 of the detection unit 100D. FIG. 4A is a diagram showing an example of the configuration of the upper surface side of the wiring board 150 of the detection unit 100D. FIG. 4B is a diagram showing an example of the configuration of the lower surface side of the wiring board 150 of the detection unit 100D. Since FIG. 4B shows the configuration of the lower surface side of the wiring board 150, the Y direction is opposite to that of FIG. 4A.

[0015] Fig. 5A is a diagram showing an example of the configuration of the upper surface side of wiring substrate 160 of detection unit 100D. Fig. 5B is a diagram showing an example of the configuration of the lower surface side of wiring substrate 160 of detection unit 100D. In Fig. 5B, the Y direction is reversed from Fig. 5A in order to show the configuration of the lower surface side of wiring substrate 160.

[0016] The detection unit 100D includes a case 110, a strain generator 120, a strain sensor 130, a spacer 141, metal pins 145A and 145B, a wiring board 150, a ground layer 151, feed lines 152, 153 and 154, a wiring board 160, an antenna element 161, coupling lines 170A and 170B, and a circuit unit 180.

[0017] Of these components of the detector 100D, the spacer 141, the screw 142, the metal pins 145A and 145B, the wiring board 150, the ground layer 151, the feed lines 152, 153 and 154, the wiring board 160, the antenna element 161, and the coupling lines 170A and 170B form the antenna device 100A.

[0018] Furthermore, among these components of the detection unit 100D, the spacer 141, the screw 142, the metal pins 145A, 145B, the wiring board 150, the ground layer 151, the power supply lines 152, 153, 154, the wiring board 160, the antenna element 161, the coupling lines 170A, 170B, and the circuit unit 180 constitute the circuit board unit 140.

[0019] In the detection unit 100D, the lower side (-Z direction side) is an example of the first side, and the upper side (+Z direction side) is an example of the second side. The direction connecting the first side and the second side is the up-down direction.

[0020] Case 110 is an example of a housing. Metal pin 145A is an example of a first connection portion, and metal pin 145B is an example of a second connection portion. Wiring board 150 is an example of a first substrate, and of feed lines 152, 153, and 154, feed lines 152 and 153 are an example of a first feed line, and feed lines 152 and 154 are an example of a second feed line. Wiring board 160 is an example of a second substrate. Coupled line 170A is an example of a first coupled line, and coupled line 170B is an example of a second coupled line. Circuit unit 180 is an example of a communication unit.

[0021] <Case 110> The case 110 has a lower case 110L and an upper case 110U. Because the detection unit 100D performs wireless communication, the case 110 is formed of a dielectric material such as resin. The case 110 has a circular ring shape in a plan view. The case 110 houses at least a portion of the main body 121 of the flexure element 120, a protrusion 122 provided on the side of the main body 121, and the circuit board unit 140. The reason that the case 110 houses at least a portion of the main body 121 of the flexure element 120 is that the lower and upper ends of the main body 121 protrude from the case 110.

[0022] <Lower case 110L> The lower case 110L has a lower surface 111L and an opening 112L. The lower surface 111L is the lower surface of the detection unit 100D and the lower surface of the case 110. However, the lower surface 121A of the strain generating element 120 protrudes downward more than the lower surface 111L. The lower case 110L is, for example, the lower half of the case 110 in the up-down direction.

[0023] The lower case 110L has an opening 112L (see FIG. 2) in the center. The opening 112L is a circular opening in a plan view, and has an opening shape that matches the planar shape of the lower end of the main body 121 of the strain element 120.

[0024] The lower case 110L, together with the upper case 110U, forms an accommodation section, which is a space for accommodating the flexure body 120. The lower end of the main body 121 of the flexure body 120 is inserted into the opening 112L. The size and shape of the opening 112L in a plan view are adjusted so that, when the lower end of the main body 121 of the flexure body 120 is inserted, there is almost no gap between the opening 112L and the outer surface 121C of the lower end of the main body 121. In addition, an O-ring 115L is provided between the opening 112L of the lower case 110L and the flexure body 120, ensuring waterproofing and dustproofing.

[0025] Furthermore, the lower case 110L has a wall surrounding the opening 112L. This wall has a shape that matches the outer circumferential shape of the lower one of the two convex portions 122 of the flexure element 120, and by engaging with the linear portion of the outer periphery of the convex portion 122, it prevents the flexure element 120 from rotating relative to the lower case 110L in a plan view.

[0026] The lower case 110L also accommodates the lower half of the circuit board unit 140 radially outward from the portion where the flexure element 120 is disposed. In this state, the flexure element 120 is accommodated in the central opening of the circuit board unit 140.

[0027] <Upper case 110U> Upper case 110U has the same shape as lower case 110L in a plan view, and has an upper surface 111U and an opening 112U. As an example, upper case 110U is the upper half of case 110 in the vertical direction, and has a configuration in which lower case 110L is turned upside down. Upper surface 111U is the upper surface of detection unit 100D and is also the upper surface of case 110. However, upper surface 121B of strain generating body 120 protrudes upward more than upper surface 111U.

[0028] Although a configuration in which the upper case 110U is the upper half of the case 110 in the up-down direction will be described here, the case 110 may be divided at any position in the up-down direction as long as it can accommodate the circuit board unit 140 and the portion of the main body 121 of the strain element 120 other than the upper and lower ends when the upper case 110U and the lower case 110L are combined. Also, the case 110 is not limited to a configuration in which it is divided into upper and lower parts, and may be divided, for example, along a diameter passing through the center of a circle in a plan view.

[0029] The opening 112U is formed in the same position as the opening 112L of the lower case 110L in a plan view, and has the same opening shape. The upper end of the main body 121 of the flexure element 120 is inserted into the opening 112U. The size and shape of the opening 112U in a plan view are adjusted so that, when the upper end of the main body 121 of the flexure element 120 is inserted, there is almost no gap between the opening 112U and the outer surface 121C of the upper end of the main body 121. In addition, an O-ring 115U is provided between the opening 112U of the upper case 110U and the flexure element 120, ensuring waterproof and dustproof properties.

[0030] Additionally, upper case 110U has a wall surrounding opening 112U. This wall has a shape that matches the outer circumferential shape of upper convex portion 122 of two convex portions 122 of flexure element 120, and by engaging with the linear portion of the outer periphery of convex portion 122, it prevents flexure element 120 from rotating relative to upper case 110U in plan view.

[0031] The upper case 110U also accommodates the upper half of the circuit board unit 140 radially outward from the portion where the flexure element 120 is disposed. In this state, the flexure element 120 is accommodated in the central opening of the circuit board unit 140.

[0032] With the strain body 120 and circuit board unit 140 mounted inside the lower case 110L, the upper case 110U is fixed to the lower case 110L as shown in FIG. 1 by inserting screws 118 (see FIG. 2) into the screw holes and fastening the screws 118 to the screw holes of the lower case 110L via O-rings 116 (see FIG. 2) for ensuring waterproofing and dustproofing. At this time, an O-ring 117 is sandwiched between the outer periphery of the lower case 110L and the outer periphery of the upper case 110U, thereby sealing and ensuring waterproofing and dustproofing. At this time, recesses on the outer peripheries of the wiring boards 150 and 160 of the circuit board unit 140 engage with the screw holes of the lower case 110L, so that the circuit board unit 140 is fixed in place without shifting while housed in the case 110. Furthermore, wiring board 150 has through holes into which the protrusions of lower case 110L are inserted, and is fixed to lower case 110L by thermal caulking with the protrusions inserted into the through holes.

[0033] In the case 110 as described above, the lower surface 121A of the main body 121 of the flexure body 120 is exposed from the opening 112L of the lower case 110L, and the upper surface 121B of the main body 121 of the flexure body 120 is exposed from the opening 112U of the upper case 110U. Therefore, with regard to the flexure body 120, the case 110 exposes the lower end portion (the portion on the lower surface 121A side) and the upper end portion (the portion on the upper surface 121B side) of the main body 121, and houses the rest of the parts.

[0034] <String body 120> The flexure element 120 has a main body 121, two protrusions 122, and a through-hole 123. The flexure element 120 is preferably made of a metal material such as stainless steel.

[0035] Main body 121 is a portion surrounding through-hole 123, and has lower surface 121A located at the lower end, upper surface 121B located at the upper end, and outer surface 121C. Lower surface 121A is an example of a first end surface, and upper surface 121B is an example of a second end surface. Of main body 121, the lower end portion on the lower side where lower surface 121A is located is an example of a first end portion, and the upper end portion on the upper side where upper surface 121B is located is an example of a second end portion. Main body 121 is a cylindrical portion, and has through-hole 123 that is circular in plan view provided in the center.

[0036] A lower end of main body 121 is inserted through opening 112L of lower case 110L, and lower surface 121A protrudes downward beyond lower surface 111L of lower case 110L. An upper end of main body 121 is inserted through opening 112U of upper case 110U, and upper surface 121B protrudes upward beyond upper surface 111U of upper case 110U.

[0037] The outer surface 121C is the outer side surface of the cylindrical main body 121, and is provided with two protrusions 122 in the center in the Z direction. The two protrusions 122 are provided spaced apart in the up-down direction in the center in the Z direction of the outer surface 121C.

[0038] Strain sensors 130 are provided in a portion of the outer surface 121C between the two protrusions 122. As an example, eight strain sensors 130 are provided, including four strain sensors 130 for detecting strain in the Z-axis direction and four strain sensors 130 for detecting strain in the X- or Y-direction. The eight strain sensors 130 are provided at four locations at 90-degree intervals around the circumferential direction of the outer surface 121C, with one strain sensor 130 for detecting strain in the Z-axis direction and one strain sensor 130 for detecting strain in the X- or Y-direction paired together. The portion of the outer surface 121C where the strain sensors 130 are provided may be a flat surface. The four flat surfaces are provided at equal intervals around the circumferential direction of the outer surface 121C. That is, the four flat surfaces are provided at 90-degree intervals around the circumferential direction of the outer surface 121C.

[0039] Convex portion 122 protrudes outward from outer surface 121C in plan view, and is located above lower surface 121A and below upper surface 121B in the vertical direction. Therefore, outer surface 121C is located above and below two convex portions 122, and outer surface 121C is also located between two convex portions 122.

[0040] The protrusions 122 are annular portions that protrude radially outward from the outer surface 121C, and part of the outer periphery is chamfered at, for example, four locations at 90-degree intervals to prevent rotation inside the lower case 110L and the upper case 110U. The lower case 110L and the upper case 110U engage with the chamfered portions, thereby fixing the protrusions 122 so as not to rotate inside the case 110. Furthermore, the two protrusions 122 abut against the inner walls of the lower case 110L and the upper case 110U in the Z direction, thereby preventing the flexure element 120 from shifting in the Z direction inside the case 110. Furthermore, the protrusions 122 are larger than the openings 112L and 112U of the lower case 110L and the upper case 110U, and therefore the flexure element 120 can be prevented from falling off from the openings 112L or 112U.

[0041] The through hole 123 penetrates the center of the main body 121 in a plan view so as to connect the lower surface 121A and the upper surface 121B. The through hole 123 has an opening size that matches the planar size of the lock bolt 21 (see FIG. 8C) of the fastening mechanism 20 (see FIG. 8C) to be inserted therethrough. The through hole 123 is a cylindrical hole, and connects the lower surface 121A and the upper surface 121B of the strain element 120.

[0042] As an example, when a member to be fastened (for example, bottom wall 101G of waveguide device 100G in FIG. 8C) abuts against lower surface 121A of strain body 120 via hemispherical washer 25 (see FIG. 8C) and fastening mechanism 20 abuts against upper surface 121B, a fastening axial force is applied in a direction penetrating through through hole 123 (Z direction), and strain body 120 is compressed in the up-down direction, causing strain as outer surface 121C of strain body 120 flexes and bulges outward, generating distortion.

[0043] <Strain sensor 130> The strain sensor 130 is provided on the outer surface 121C of the main body 121 of the flexure body 120, in a portion between the two protrusions 122. The strain sensor 130 has one or more strain detection elements and detects the strain of the flexure body 120. For example, each strain detection element uses a strain resistance element whose resistance value changes depending on the amount of strain. Four strain detection elements may be provided and connected in a bridge configuration.

[0044] The strain detection elements may be formed on the outer surface 121C by printing a composite resistor containing cermet or a composite resistor whose binder is synthetic resin. In this case, the strain detection elements can be easily and reliably formed at predetermined installation positions on the outer surface 121C. In particular, since the printing, drying, and curing of the strain detection elements can be performed collectively on the multiple flexure bodies 120 while the multiple flexure bodies 120 are arranged side by side, the strain detection elements can be easily and reliably formed on the multiple flexure bodies 120.

[0045] Furthermore, for example, the strain detection element may be mounted on a rigid or flexible substrate and then attached to the outer surface 121C together with the rigid or flexible substrate. In this case, too, the strain detection element can be easily and reliably installed at a predetermined installation position on the outer surface 121C. Note that the portion of the outer surface 121C where the strain detection element is provided is preferably flat.

[0046] <Spacer 141 and screw 142> The spacers 141 are components that connect the wiring boards 150 and 160. The wiring boards 150 and 160 are joined together by a plurality of screws 142. The four spacers 141 are aligned with the four screw holes 150B of the wiring board 150 and the four screw holes 160B of the wiring board 160 (see FIG. 3 ), and are fixed between the wiring boards 150 and 160 by screws 142 inserted into the four screw holes 150B and screws 142 (not shown) inserted into the four screw holes 160B. By fixing the four spacers 141 between the wiring boards 150 and 160 in this manner, the wiring boards 150 and 160 are mechanically joined together. Since the lengths of the four spacers 141 are equal, the wiring boards 150 and 160 are parallel, and the distance between the wiring boards 150 and 160 is constant. The spacers 141 are made of an insulating material, such as resin, for example.

[0047] <Metal pins 145A and 145B> The lower end of metal pin 145A is inserted into a through-hole provided between lands 151A and 156A of wiring board 150, and the upper end is inserted into a through-hole provided between coupled line 170A and land 162A of wiring board 160, and they are fixed by soldering. In this way, metal pin 145A electrically connects feed line 153 and coupled line 170A.

[0048] The lower end of the metal pin 145B is inserted into a through-hole provided between the lands 151B and 156B of the wiring board 150, and the upper end is inserted into a through-hole provided between the coupled line 170B and the land 162B of the wiring board 160, and the metal pin 145B is fixed by soldering. In this way, the metal pin 145B electrically connects the feed line 154 and the coupled line 170B.

[0049] For example, such metal pins 145A and 145B can be made of copper, brass, etc. Also, instead of the metal pins 145A and 145B, a conductor made of copper or the like may be used.

[0050] <Wiring board 150> As an example, wiring board 150 is a wiring board conforming to FR-4 (Flame Retardant type 4) standards. Wiring board 150 has an annular shape in a plan view and is housed in lower case 110L. In FIGS. 4A and 4B, the point where two dashed lines intersect at right angles represents the center of the annular shape of wiring board 150. Wiring board 150, along with wiring board 160, is parallel to the XY plane. The lower surface of wiring board 150 is an example of a first surface, and the upper surface is an example of a second surface.

[0051] The wiring substrate 150 has an annular shape with an opening 150A in the center, and has, for example, six notches provided along the circumferential direction on the inner periphery and eight notches provided along the circumferential direction on the outer periphery. The opening 150A is an example of a first opening that penetrates between the lower surface (first surface) and the upper surface (second surface). The diameter of the opening 150A is set to a value slightly larger than the diameter of the protrusion 122 of the strain element 120 and is equal to the diameter of the opening 160A of the wiring substrate 160.

[0052] The six notches on the inner periphery and the eight notches on the outer periphery are provided to avoid the 14 protrusions that have the 14 screw holes of the lower case 110L. The wiring board 150 is fixed inside the lower case 110L by the 14 notches engaging with the 14 protrusions.

[0053] For example, wiring board 150 does not have an inner layer. A ground layer 151 is provided on the entire lower surface (see FIG. 4B) of wiring board 150. Two lands 151A and 151B are provided on ground layer 151. For example, ground layer 151 is made of copper foil. Lands 151A and 151B are surrounded by ground layer 151 but are separated from ground layer 151. When ground layer 151 is fabricated, portions of a single copper foil are separated from ground layer 151 and used as lands 151A and 151B.

[0054] <Land 151A, 151B> Land 151A is connected to land 156A on the upper surface of wiring board 150 via a through hole that penetrates wiring board 150 in the thickness direction (Z direction), and land 151B is connected to land 156B on the upper surface of wiring board 150 via a through hole that penetrates wiring board 150 in the thickness direction (Z direction).

[0055] <Power supply lines 152 to 154, power supply circuit 155, lands 156A and 156B, and a plurality of terminals 157> On the upper surface of wiring board 150 (see FIG. 4A), there are provided power supply circuit 155 configured with power supply lines 152 to 154, lands 156A and 156B, and a plurality of terminals 157. Power supply lines 152 to 154, lands 156A and 156B, and a plurality of terminals 157 can be fabricated, for example, by patterning copper foil.

[0056] The feed lines 152 to 154 overlap with the ground layer 151 on the lower surface of the wiring board 150, forming a microstrip line. The feed line 152 is connected to the circuit unit 180 and branches into feed lines 153 and 154 at point A. Therefore, a signal output from the circuit unit 180 is distributed to the feed lines 153 and 154. As shown in FIG. 4A , the feed lines 153 and 154 extend along an arc of radius r from the center of the circular shape of the wiring board 150. A land 156A is connected to the tip of the feed line 153, and a land 156B is connected to the tip of the feed line 154.

[0057] The characteristic impedance of the feed line 152 is, for example, 50 Ω. This is set to the impedance of the high-frequency input / output terminal to which the feed line 152 is connected to the circuit unit 180, which is 50 Ω. The characteristic impedance of the feed lines 153 and 154 is, for example, 100 Ω. Because the feed lines 153 and 154 are connected to the feed line 152 at point A, the combined characteristic impedance of the feed lines 153 and 154 is 50 Ω when viewed from point A.

[0058] If the electrical length of the wavelength of radio waves at the operating frequency of antenna element 161 is λe, the length of feed line 154 is λe / 4 longer than the length of feed line 153. Therefore, the phase of the signal transmitted from circuit unit 180 to land 156B is delayed by π / 2 (rad) from the phase of the signal transmitted from circuit unit 180 to land 156A. This is to enable circularly polarized radio waves to be radiated from antenna element 161. Details of this will be described later. The operating frequency of antenna element 161 is, for example, a frequency included in the 920 MHz band.

[0059] The feeder line 152 may be divided into a feeder line connected to the terminal of the circuit unit 180 and a feeder line connected to the feeder line 153 and a feeder line connected to the feeder line 154 .

[0060] Land 156A is connected to land 151A on the underside of wiring board 150 via a through hole that penetrates wiring board 150 in the thickness direction (Z direction), and land 156B is connected to land 151B on the underside of wiring board 150 via a through hole that penetrates wiring board 150 in the thickness direction (Z direction).

[0061] The lower end of metal pin 145A (see FIG. 3) is inserted into the through-hole between lands 156A and 151A and fixed by soldering. The lower end of metal pin 145B (see FIG. 3) is inserted into the through-hole between lands 156B and 151B and fixed by soldering.

[0062] The plurality of terminals 157 (see FIG. 4A) are terminals to which lead wires connected to the strain sensor 130 are connected. The plurality of terminals 157 are connected to the circuit section 180 via wiring (not shown) provided on the upper surface of the wiring board 150.

[0063] <Wiring board 160> As an example, wiring board 160 is a wiring board conforming to FR-4 standards, similar to wiring board 150. Wiring board 160 has an annular shape in plan view, similar to wiring board 150, and is housed in upper case 110U. In FIGS. 5A and 5B, the point where two dashed lines intersect at right angles indicates the center of the annular shape of wiring board 160. The bottom surface of wiring board 160 is an example of a third surface, and the top surface is an example of a fourth surface. The bottom surface of wiring board 160 faces the top surface of wiring board 150.

[0064] The wiring board 160 has an annular shape with an opening 160A in the center, and six openings, for example, are provided along the circumferential direction, and twelve notches are provided along the periphery. The openings 160A are an example of a second opening that penetrates between the lower surface (third surface) and the upper surface (fourth surface). The upper case 110U has fourteen screw holes (see FIG. 2) and fourteen protrusions that protrude downward from the lower surface of the upper case 110U. The fourteen screw holes penetrate each of the fourteen protrusions. The six openings and eight of the twelve notches are provided to avoid the fourteen protrusions of the upper case 110U.

[0065] When lower case 110L and upper case 110U are aligned with circuit board unit 140 sandwiched therebetween, the upper ends of the 14 protrusions of lower case 110L abut against the lower ends of the 14 protrusions of upper case 110U. In this state, when screws 118 are inserted into the screw holes of upper case 110U, the tips of screws 118 that have passed through the protrusions of upper case 110U enter the interiors of the protrusions of lower case 110L, thereby fastening lower case 110L and upper case 110U together. In this state, circuit board unit 140 is fixed in the Z direction between lower case 110L and upper case 110U, and wiring boards 150 and 160 are fixed in place by the 14 protrusions of lower case 110L and upper case 110U to prevent misalignment.

[0066] <Antenna element 161> Antenna element 161 is formed on the upper surface of wiring board 160 (see FIG. 5A). Antenna element 161 has an annular shape with an inner radius a and an outer radius b, and its outer periphery at the position of outer radius b is located radially inward of the outer periphery of wiring board 160. Antenna element 161 can be produced, for example, by patterning copper foil formed on the upper surface of wiring board 160.

[0067] Antenna element 161 is annular, but has twelve notches on its outer periphery so as to avoid the twelve notches on the outer periphery of wiring board 160. The twelve notches of antenna element 161 are formed along the circumferential direction on the outer periphery of antenna element 161.

[0068] As an example, antenna element 161 is an antenna element for a patch antenna. Although ground layer 151 (see FIG. 4B) exists below antenna element 161, a fastened member (for example, bottom wall 101G of waveguide device 100G in FIG. 8C ) located further below is larger than ground layer 151 in a plan view, and therefore the ground layer of the patch antenna becomes the fastened member (for example, bottom wall 101G of waveguide device 100G in FIG. 8C ). In other words, antenna element 161 is capacitively coupled to the fastened member (for example, bottom wall 101G of waveguide device 100G in FIG. 8C ) to form a patch antenna.

[0069] Here, there are various wireless communication methods for the communication unit included in the circuit unit 180 that supplies power to the antenna element 161, such as RFID (Radio Frequency Identifier) ​​and LPWA (Low Power Wide Area), but here we will explain the RFID form as an example.

[0070] In such a case, the antenna element 161 is required to have the following performance, for example: Resonate at approximately 920 MHz and ensure sufficiently low return loss. Meet the 920 MHz RFID frequency band (7 MHz from 916 MHz to 923 MHz). Obtain a gain of approximately 4 dBi. Be able to radiate circularly polarized waves. In this embodiment, there is provided an antenna device 100A and a detection unit 100D that include an antenna element 161 that meets these performance requirements.

[0071] <Lands 162A and 162B> In plan view, the lands 162A and 162B (see FIG. 5A) are formed inside two of the twelve cutouts of the wiring board 160. As an example, the lands 162A and 162B can be produced together with the antenna element 161 by patterning copper foil formed on the upper surface of the wiring board 160.

[0072] Land 162A is connected to a coupled line 170A (see FIG. 5B) provided on the lower surface of wiring board 160 via a through hole that penetrates wiring board 160 in the thickness direction (Z direction). Land 162B is connected to a coupled line 170B (see FIG. 5B) provided on the lower surface of wiring board 160 via a through hole that penetrates wiring board 160 in the thickness direction (Z direction).

[0073] <Coupled line 170A, 170B> The coupled lines 170A and 170B are formed on the lower surface of the wiring substrate 160. The coupled lines 170A and 170B are arranged at positions spaced 90 degrees apart from the center of the annular shape of the wiring substrate 160 in the circumferential direction of the annular shape of the wiring substrate 160.

[0074] The coupled lines 170A and 170B extend along the radial direction of the annular shape of the wiring board 160. The lengths of the coupled lines 170A and 170B along the radial direction are equal to each other and are equal to or less than ¼ of the electrical length λe of the wavelength of radio waves at the operating frequency of the antenna element 161. When the lengths of the coupled lines 170A and 170B are equal to or less than λe / 4, the coupled lines 170A and 170B become equivalent to a parallel capacitance connected in parallel to the antenna element 161, and can adjust the impedance of the antenna element 161 in a resonant state. This will be described in detail later.

[0075] The radially outer end of coupled line 170A is connected to land 162A via a through hole that penetrates wiring board 160 in the thickness direction (Z direction). The radially outer end of coupled line 170B is connected to land 162B via a through hole that penetrates wiring board 160 in the thickness direction (Z direction). The radially outer ends of coupled lines 170A and 170B function as lands.

[0076] The upper end of metal pin 145A (see FIG. 3) is inserted into the through-hole between land 162A and coupled line 170A and fixed by soldering. The upper end of metal pin 145B (see FIG. 3) is inserted into the through-hole between land 162B and coupled line 170B and fixed by soldering.

[0077] Therefore, the coupled line 170A is connected to the circuit unit 180 via a feed path formed by the metal pin 145A, the land 156A, the feed line 153, and the feed line 152. The coupled line 170B is connected to the circuit unit 180 via a feed path formed by the metal pin 145B, the land 156B, the feed line 154, and the feed line 152.

[0078] The coupled lines 170A and 170B are capacitively coupled to the antenna element 161. Therefore, the antenna element 161 is fed with power at the portion where the coupled lines 170A and 170B overlap. Furthermore, the length of the feed path between the circuit unit 180 and the coupled line 170B is longer by λe / 4 than the length of the feed path between the circuit unit 180 and the coupled line 170A. Therefore, the phase of the signal transmitted from the circuit unit 180 to the coupled line 170B is delayed by π / 2 (rad) from the phase of the signal transmitted from the circuit unit 180 to the coupled line 170A. In other words, the phase difference is π / 2 (rad), and the signal transmitted from the circuit unit 180 to the coupled line 170B is delayed in phase from the signal transmitted from the circuit unit 180 to the coupled line 170A.

[0079] When a transmission signal is transmitted from circuit unit 180 to coupled lines 170A and 170B, coupled line 170B supplies power to antenna element 161 with a delay of π / 2 (rad) compared to coupled line 170A. The amplitudes of the transmission signals output from coupled lines 170A and 170B to antenna element 161 are the same. Therefore, antenna device 100A and detection unit 100D radiate left-handed circularly polarized radio waves in the Z direction.

[0080] In the above description, the coupled lines 170A and 170B shown in FIG. 5B are connected to the lands 162A and 162B (see FIG. 5A) via through-holes at their radially outer ends. However, the positions of the lands 162A and 162B may be shifted radially inward, and the radially inner ends of the coupled lines 170A and 170B may be connected to the lands 162A and 162B via through-holes. In this case, the positions of the lands 151A and 151B (see FIG. 4B) and the lands 156A and 156B (see FIG. 4A) may also be shifted radially inward.

[0081] <Circuit section 180> The circuit unit 180 is connected to the power supply circuit 155 and is also connected to the strain sensor 130 via wiring (not shown). The circuit unit 180 incorporates a control unit that generates a strain detection signal that indicates the degree of strain of the strain element 120 based on the output of the strain sensor 130, and a communication unit that performs wireless communication using the antenna element 161. The detection unit 100D is a passive device that operates without a power source such as a battery, and the circuit unit 180 does not have a memory.

[0082] The communication unit generates DC power by rectifying a signal received by the antenna element 161 from the reader device of the detection unit 100D, and supplies the generated power to the control unit to operate the control unit. The control unit generates a strain detection signal indicating the degree of strain of the strain element 120 and transmits it to the communication unit. The communication unit radiates the strain detection signal as backscatter through the antenna element 161. The radiated strain detection signal is received by the reader device of the detection unit 100D. As mentioned above, there are various wireless communication methods for the communication unit, such as RFID and LPWA, but here we will explain the RFID form as an example.

[0083] In the above description, the detection unit 100D is a passive device that does not have a battery, but the present invention is not limited to this. The detection unit 100D may be configured to include at least one of a battery and a memory.

[0084] Furthermore, although the above describes a configuration in which the antenna device 100A radiates left-handed circularly polarized radio waves from the antenna element 161, it may also be configured to radiate right-handed circularly polarized radio waves from the antenna element 161 by swapping the lengths of the feeder lines 153 and 154.

[0085] In the above description, the antenna device 100A includes the metal pins 145A and 145B and the coupling lines 170A and 170B, and the antenna element 161 emits circularly polarized radio waves. However, the antenna device 100A may include only one of the metal pin 145A and the coupling line 170A, or the metal pin 145B and the coupling line 170B, and may emit linearly polarized radio waves from the antenna element 161.

[0086] Furthermore, although the above description has been given of a configuration in which the detection unit 100D includes two wiring boards 150 and 160, it may also be configured such that an antenna element 161 is formed on a single wiring board and that circularly polarized or linearly polarized radio waves are emitted.

[0087] <Detection device 100> Fig. 6A is a diagram showing an example of the configuration of a detection device 100 according to an embodiment. The detection device 100 includes a detection unit 100D and a waveguide device 100G. Fig. 6B is a diagram showing a state in which the detection device 100 is separated into the detection unit 100D and the waveguide device 100G.

[0088] <Relationship between the detection unit 100D and the wave-guiding device 100G> The detection unit 100D is housed in the bottom of the interior of the waveguide device 100G, and is fixed to the structure together with the waveguide device 100G by inserting bolts of the fastening mechanism into the through-holes 123 of the flexure body 120 housed in the case 110 and the opening 101GA of the waveguide device 100G. The opening 101GA is an example of a bottom wall opening. In this state, the fastening mechanism and the fastened member abut against the lower and upper surfaces of the main body of the flexure body 120 that protrudes upward and downward from the case 110. The lower and upper surfaces of the main body of the flexure body 120 protrude in the -Z direction and the +Z direction, respectively, beyond the case 110. The fastened member is the bottom wall 101G of the waveguide device 100G.

[0089] The installation structure of the detection unit 100D can be, for example, a structure in which the fastening mechanism abuts against the lower surface of the main body of the strain body 120 and the fastened member abuts against the upper surface of the main body, or a structure in which the fastened member abuts against the lower surface of the main body of the strain body 120 and the fastening mechanism abuts against the upper surface of the main body.

[0090] <Waveguide device 100G> The waveguide device 100G has a bottom wall 101G and a side wall 102G. The bottom wall 101G and the side wall 102G are an example of a waveguide section. The waveguide device 100G is a cylindrical metal member with a bottom. The waveguide device 100G accommodates the detector 100D in an internal space (accommodation section) surrounded by the bottom wall 101G and the side wall 102G.

[0091] The waveguide device 100G is placed in a hole provided in a building. If the hole has a diameter of 200 mm and a depth of 100 mm, for example, the waveguide device 100G has a diameter of 195 mm and a height of 100 mm. The bottom wall 101G and the side wall 102G are made of stainless steel and have a thickness of 1 mm, for example. However, the bottom wall 101G and the side wall 102G may be made of a metal other than stainless steel.

[0092] Bottom wall 101G is located at the bottom (the end on the -Z direction side) of waveguide device 100G, is a wall parallel to the XY plane, and is circular in plan view. The diameter of bottom wall 101G is slightly larger than the outer diameter of case 110 of detector 100D and is adjusted to the diameter of a hole in a building, which will be described later, so that bottom wall 101G can be housed inside the hole.

[0093] The bottom wall 101G has an opening 101GA in the center in a plan view. When the detection unit 100D is accommodated in the accommodation portion of the waveguide device 100G and the detection unit 100D is fixed to a structure together with the waveguide device 100G, a bolt portion of the fastening mechanism is inserted through the through-hole 123 of the strain body 120 and the opening 101GA.

[0094] The side wall 102G is a cylindrical wall portion extending in the +Z direction from the circular outer edge of the bottom wall 101G. For example, the side wall 102G may be welded to the bottom wall 101G or may be fixed to the bottom wall 101G with bolts or the like. Alternatively, the side wall 102G may be formed integrally with the bottom wall 101G.

[0095] The height of side wall 102G (height in the +Z direction from bottom wall 101G) is adjusted to the depth of a hole in the building structure, which will be described later. That is, the height of side wall 102G is equal to the depth of the hole in the building structure. Note that the height of side wall 102G may be at least two-thirds the depth of the hole when bottom wall 101G is in contact with the bottom surface of the hole. Furthermore, the end of side wall 102G on the +Z direction side may protrude further in the +Z direction than the hole when waveguide device 100G is inserted in the hole.

[0096] When the detecting unit 100D is housed at the bottom of the inside of the waveguide device 100G, and the antenna device included in the detecting unit 100D emits circularly polarized radio waves, the waveguide device 100G reflects the radio waves in the +Z direction and guides the radio waves in the +Z direction, thereby operating like a waveguide. The diameter of the waveguide device 100G may be equal to or slightly larger than the diameter of a general circular waveguide compatible with the operating frequency (e.g., 920 MHz) of the antenna device included in the detecting unit 100D. Even if the diameter of the waveguide device 100G is larger than the diameter of a general circular waveguide compatible with the operating frequency of the antenna device, the waveguide device 100G can still function as a waveguide for the antenna device.

[0097] <Installation structure for comparison of detection unit 100D> Before describing the installation structure of the embodiment of the detector 100D using the waveguide device 100G, a comparative installation structure of the detector 100D using the washer 30 will be described with reference to FIGS. 7A to 7C.

[0098] FIG. 7A is a diagram showing an example of a comparative installation structure for the detection unit 100D using a washer 30. FIG. 7B is a diagram showing an example of an installation structure for the detection unit 100D installed using the comparative installation structure. FIG. 7C shows an example of a cross-sectional configuration taken along the line AA in FIG. 7B. FIGS. 7A to 7C also show the fixing unit 10 and the fastening mechanism 20. Note that FIG. 7C shows the fixing unit 10 and the washer 30 in cross section, and the detection unit 100D and the fastening mechanism 20 in side view in the YZ plane.

[0099] The comparative installation structure of the detector 100D is a structure in which the detector 100D of the embodiment is fastened to the inside of a hole in a building using a washer 30 instead of the wave-guiding device 100G. The washer 30 is a disk-shaped metal member and is a fastened member for comparison.

[0100] The fixed part 10 is an example of a structure, and is a part of a structure such as a building, a road, a tunnel, or a bridge pier, or a member fixedly attached to a structure. Here, as an example, a form will be described in which the fixed part 10 is the inner wall of a tunnel and is a member made of concrete.

[0101] The fixing portion 10 has a hole 12 recessed from the surface 11. As an example, the surface 11 is the surface of the inner wall of a tunnel, and the hole 12 is a hole formed in the surface of the inner wall of the tunnel. A rock bolt 21 is buried in the bottom of the hole 12 to reinforce the fixing portion 10. For example, trains powered by diesel engines or trains powered by electric motors driven by electricity generated by diesel engines do not receive power from overhead lines, so there are no overhead lines along the tracks. For this reason, train tunnels are narrow. To bury the rock bolt 21 to reinforce the inner wall of such a train tunnel, the hole 12 is formed in the surface 11 so that the rock bolt 21 does not protrude from the surface 11, or the amount by which the rock bolt 21 protrudes from the surface 11 is reduced.

[0102] The fixed part 10 is connected to the ground. That is, the fixed part 10 is connected to the ground. The lock bolt 21 is buried in the fixed part 10 at the bottom of the hole 12, and is therefore connected to the ground.

[0103] When fixing the detection unit 100D inside the hole 12 using the fastening mechanism 20, the washer 30, the hemispherical washer 25, the detection unit 100D, and the nut 22 are placed in this order inside the hole 12, as shown in FIG. 7A . The washer 30 has an opening through which the lock bolt 21 passes. The diameter of the washer 30 is adjusted to match the diameter of the hole 12.

[0104] From the state shown in FIG. 7A, when the lock bolt 21 is inserted through the opening of the washer 30, the through hole of the hemispherical washer 25, and the through hole 123 of the strain body 120 of the detection unit 100D (see FIGS. 6A and 6B), and the nut 22 is screwed onto the bolt shaft from the tip end side of the lock bolt 21, the washer 30 and the detection unit 100D are fixed at the bottom of the hole 12 by the fastening mechanism 20, as shown in FIGS. 7B and 7C.

[0105] 7B and 7C, washer 30 is provided between the bottom surface of hole 12 and detection unit 100D. Washer 30 is fixed to the bottom surface of hole 12 by screwing together lock bolt 21 and nut 22 of fastening mechanism 20, with hemispherical washer 25 sandwiched between washer 30 and detection unit 100D. In this state, detection unit 100D is provided between nut 22 and washer 30, with hemispherical washer 25 sandwiched between washer 30 and detection unit 100D. Washer 30 is connected to lock bolt 21, and is therefore connected to ground.

[0106] 7B and 7C, when the lock bolt 21 and the nut 22 are tightened, the washer 30 and the detection unit 100D are fixed to the bottom surface of the hole 12. At this time, the lower surface of the main body of the strain element 120 of the detection unit 100D abuts against the upper surface of the washer 30 via the hemispherical washer 25, and the upper surface of the main body abuts against the lower surface of the nut 22.

[0107] As a result, a fastening axial force in the axial direction (Z direction) of the bolt shaft of the lock bolt 21 is applied to the main body of the strain body 120, and the strain body 120 can withstand the fastening axial force applied from the nut 22. A strain corresponding to the tightening torque of the nut 22 is generated in the strain body 120, and the strain generated in the strain body 120 is detected by a plurality of strain sensors 130 provided on the strain body 120 of the detection unit 100D. A strain detection signal indicating the strain is radiated to the outside of the case 110 as a backscattered radio wave by the communication unit of the detection unit 100D.

[0108] However, the detection unit 100D is located at the bottom of the hole 12 and is offset in the -Z direction from the surface 11 of the fixed unit 10. Furthermore, the bottom surface of the cylindrical hole 12 is covered with a washer 30, but the side wall of the hole 12 is a concrete wall.

[0109] As a result, a portion of the radio waves emitted outside the case 110 by the communication unit of the detection unit 100D is absorbed by the concrete side walls of the hole 12, and the signal level of the radio waves emitted outside the hole 12 is significantly attenuated.

[0110] As a result, the reader device of the detection unit 100D may not be able to receive backscattered radio waves including the distortion detection signal from the detection unit 100D, and may not be able to determine the fastening state of the nut 22. In the embodiment, such a problem is solved by using a waveguide device 100G.

[0111] <Installation structure of the embodiment of the detection unit 100D> 8A to 8C are diagrams showing an example of an installation structure of an embodiment of the detecting unit 100D. FIG. 8C shows an example of the cross-sectional configuration along the arrow B-B in FIG. 8B. FIGS. 8A to 8C show the fixing unit 10 and the fastening mechanism 20. FIG. 8C shows the fixing unit 10 and the wave-guiding device 100G in cross section, and the detecting unit 100D and the fastening mechanism 20 as viewed from the YZ plane. The fixing unit 10 and the fastening mechanism 20 shown in FIGS. 8A to 8C are the same as the fixing unit 10 and the fastening mechanism 20 shown in FIGS. 7A to 7C.

[0112] In the installation structure of the embodiment of the detection unit 100D, when the detection unit 100D is fixed inside the hole 12 using the fastening mechanism 20, the waveguide device 100G, the hemispherical washer 25, the detection unit 100D, and the nut 22 are inserted into the hole 12 in this order, as shown in FIG. 8A.

[0113] If washer 30 (see FIGS. 7A to 7C) has been previously secured to lock bolt 21 with a nut, washer 30 and the nut can be removed, and waveguide device 100G, hemispherical washer 25, detection unit 100D, and nut 22 can be placed in hole 12 in this order. In other words, because waveguide device 100G serves the role of washer 30, bottom wall 101G should have a structure with the same strength as washer 30.

[0114] Furthermore, when washer 30 (see FIGS. 7A to 7C) is previously fixed to lock bolt 21 with a nut, the nut may be removed, and waveguide device 100G, hemispherical washer 25, detection unit 100D, and nut 22 may be inserted into hole 12 in this order from the +Z direction side of washer 30. In this case, bottom wall 101G does not need to have a structure with the same strength as washer 30.

[0115] From the state shown in FIG. 8A, when the lock bolt 21 is inserted through the opening 101GA of the wave-guiding device 100G, the through-hole of the hemispherical washer 25, and the through-hole 123 of the strain body 120 of the detection unit 100D (see FIGS. 6A and 6B), and the nut 22 is screwed onto the bolt shaft from the tip end side of the lock bolt 21, the wave-guiding device 100G and the detection unit 100D are fixed at the bottom of the hole 12 by the fastening mechanism 20, as shown in FIGS. 8B and 8C.

[0116] 8B and 8C, bottom wall 101G of waveguide device 100G is provided between the bottom surface of hole 12 and detection unit 100D. Bottom wall 101G of waveguide device 100G is fixed to the bottom surface of hole 12 by screwing lock bolt 21 and nut 22 of fastening mechanism 20, with hemispherical washer 25 sandwiched between bottom wall 101G and detection unit 100D. In this state, detection unit 100D is provided between nut 22 and bottom wall 101G, with hemispherical washer 25 sandwiched between bottom wall 101G and bottom wall 101G. Furthermore, because bottom wall 101G is connected to lock bolt 21, waveguide device 100G is connected to ground.

[0117] 8B and 8C, when the lock bolt 21 and the nut 22 are tightened, the bottom wall 101G and the detection unit 100D are fixed to the bottom surface of the hole 12. At this time, the lower surface of the main body of the strain element 120 of the detection unit 100D abuts against the upper surface of the bottom wall 101G via the hemispherical washer 25, and the upper surface of the main body abuts against the lower surface of the nut 22.

[0118] Therefore, a fastening axial force in the axial direction (Z direction) of the bolt shaft of the lock bolt 21 is applied to the main body of the strain body 120, and the strain body 120 can withstand the fastening axial force applied from the nut 22. A strain detection signal representing the strain is radiated to the outside of the case 110 as backscattered radio waves by the communication unit of the detection unit 100D.

[0119] Since the side wall of the hole 12 is covered by the side wall 102G of the waveguide device 100G, the radio waves emitted to the outside of the case 110 by the communication unit of the detection unit 100D propagate in the +Z direction inside the waveguide device 100G and are emitted toward the +Z direction beyond the surface 11 of the fixed part 10.

[0120] Therefore, the radio waves containing the strain detection signal are emitted outside the hole 12, and the reader device of the detection unit 100D can reliably receive the radio waves containing the strain detection signal from the detection unit 100D, and can reliably determine the tightening state of the nut 22.

[0121] If the fixing part 10 is a wall part of a building or the like, has a surface opposite to the surface 11, and has a through-hole that leads from the surface opposite to the surface 11 to the hole 12, a bolt may be inserted into the through-hole from the opposite surface side instead of the lock bolt 21, and fastened with the nut 22. In this case, the head of the bolt will be located on the surface side opposite to the surface 11.

[0122] Furthermore, there is a possibility that the lock bolt 21 is attached at an angle to the bottom surface of the hole 12. In other words, there is a possibility that the lock bolt 21 is attached in an inclined state to the bottom surface of the hole 12.

[0123] In such a case, the hemispherical lower surface of the hemispherical washer 25 stably abuts against the upper surface of the bottom wall 101G of the wave-guiding device 100G in accordance with the tilt, so that the detection unit 100D can be stably fixed even when the lock bolt 21 is tilted relative to the upper surface of the bottom wall 101G.

[0124] Although the above description has been given of a configuration in which the detector 100D for detecting the axial fastening force is provided inside the waveguide device 100G, the waveguide device 100G is not limited to this configuration. For example, instead of the detector 100D for detecting the axial fastening force, the waveguide device 100G may be provided with the antenna device 100A inside, thereby improving the radiation characteristics of the antenna device 100A.

[0125] <Modification> 9A to 9C are diagrams showing an example of an installation structure of a modified embodiment of the detector 100D. FIG. 9D is a diagram showing an example of the configuration of a waveguide device 100GM of a modified embodiment. FIG. 9C shows an example of the configuration in a cross section taken along the CC arrow in FIG. 9B. FIG. 9C shows cross sections of the fixing unit 10, washer 30, and waveguide device 100GM, and shows side views of the detector 100D and fastening mechanism 20 in a YZ plane view. FIGS. 9A to 9C show the fixing unit 10 and fastening mechanism 20.

[0126] As shown in FIG. 9D , the waveguide device 100GM has a configuration in which the bottom wall 101G is removed from the waveguide device 100G of the embodiment. The waveguide device 100GM has a side wall 102G. The side wall 102G is an example of a waveguide portion. The side wall 102G is a cylindrical wall portion with openings on both ends in the -Z direction and the +Z direction. When a washer 30 is placed on the bottom surface of the hole 12, the waveguide device 100GM is combined with the washer 30 to function as a waveguide similar to the waveguide device 100G of the embodiment. In this case, the washer 30 is an example of a fastened member.

[0127] In the installation structure of the modified embodiment, when the detection unit 100D is fixed inside the hole 12 using the fastening mechanism 20, the washer 30, the hemispherical washer 25, the detection unit 100D, and the nut 22 are inserted into the hole 12 in this order, as shown in Figure 9A.

[0128] If the washer 30 has already been fixed to the lock bolt 21 with a nut, the nut can be removed, and the hemispherical washer 25, the detection unit 100D, and the nut 22 can be inserted into the hole 12 in this order from the +Z direction side of the washer 30.

[0129] 9A, the lock bolt 21 is inserted through the opening of the washer 30, the through hole of the hemispherical washer 25, and the through hole 123 of the strain body 120 of the detection unit 100D (see FIGS. 6A and 6B), the nut 22 is tightened onto the bolt shaft from the tip side of the lock bolt 21, and the waveguide device 100GM is inserted into the hole 12 and fixed with adhesive, mortar, etc. As a result, as shown in FIGS. 9B and 9C, the detection unit 100D is fixed at the bottom of the hole 12 by the fastening mechanism 20, the bottom surface of the hole 12 is covered with the washer 30, and the side wall of the hole 12 is covered with the waveguide device 100GM.

[0130] 9B and 9C, a washer 30 is provided between the bottom surface of the hole 12 and the detection unit 100D. The washer 30 is fixed to the bottom surface of the hole 12 by screwing together the lock bolt 21 and the nut 22 of the fastening mechanism 20, with a hemispherical washer 25 sandwiched between the washer 30 and the detection unit 100D. In this state, the detection unit 100D is provided between the nut 22 and the bottom wall 101G, with the hemispherical washer 25 sandwiched between the washer 30 and the nut 22. Because the washer 30 is connected to the lock bolt 21, the washer 30 is also connected to ground.

[0131] Furthermore, the waveguide device 100GM may be brought into contact with the washer 30 inside the hole 12. This allows the waveguide device 100GM to be connected to the ground via the washer 30. A conductive adhesive may be applied to the portion of the waveguide device 100GM that comes into contact with the washer 30 (the end on the -Z direction side).

[0132] 9B and 9C, when the lock bolt 21 and the nut 22 are tightened, the washer 30 and the detection unit 100D are fixed to the bottom surface of the hole 12. At this time, the lower surface of the main body of the strain element 120 of the detection unit 100D abuts against the upper surface of the washer 30 via the hemispherical washer 25, and the upper surface of the main body abuts against the lower surface of the nut 22.

[0133] Therefore, a fastening axial force in the axial direction (Z direction) of the bolt shaft of the lock bolt 21 is applied to the main body of the strain body 120, and the strain body 120 can withstand the fastening axial force applied from the nut 22. A strain detection signal representing the strain is radiated to the outside of the case 110 as backscattered radio waves by the communication unit of the detection unit 100D.

[0134] Since the side walls of the hole 12 are covered by the waveguide device 100GM, the radio waves emitted to the outside of the case 110 by the communication unit of the detection unit 100D propagate in the +Z direction within the space surrounded by the waveguide device 100GM and the washer 30, and are emitted toward the +Z direction beyond the surface 11 of the fixed part 10.

[0135] Therefore, the radio waves containing the strain detection signal are emitted outside the hole 12, and the reader device of the detection unit 100D can reliably receive the radio waves containing the strain detection signal from the detection unit 100D, and can reliably determine the tightening state of the nut 22.

[0136] It is possible that the lock bolt 21 is attached at an angle to the bottom surface of the hole 12. In other words, the lock bolt 21 may be attached in an inclined state to the bottom surface of the hole 12.

[0137] In such a case, the hemispherical lower surface of the hemispherical washer 25 stably abuts against the upper surface of the washer 30 in response to the tilt, so that the detection unit 100D can be stably fixed even when the lock bolt 21 is tilted relative to the upper surface of the washer 30.

[0138] Moreover, instead of the waveguide device 100GM, waveguide devices 100GM1 to 100GM3 shown in Figures 10A to 10C may be used. Figures 10A to 10C are diagrams showing examples of the configurations of the waveguide devices 100GM1 to 100GM3.

[0139] The waveguide device 100GM1 shown in FIG. 10A has an engagement portion 102G1 provided at the end of the side wall 102G on the +Z direction side and protruding radially outward from the side wall 102G. When the waveguide device 100GM1 is inserted into the hole 12, the engagement portion 102G1 engages with the side wall of the hole 12. As an example, three engagement portions 102G1 are provided at the end of the side wall 102G on the +Z direction side, spaced equally apart in the circumferential direction. Each engagement portion 102G1 has two notches formed in the -Z direction from the end of the side wall 102G on the +Z direction side, and the portion between the two notches is bent radially outward. In FIG. 10A, the -Z direction side corresponds to the back side of the hole 12.

[0140] For example, in a case where the hole 12 is attached facing downward in the ceiling of a tunnel, the waveguide device 100GM1 can be prevented from falling out of the hole 12. The end of the engaging portion 102G1 is located on the +Z direction side, so that even if an attempt is made to pull the waveguide device 100GM1 out of the hole 12, the end of the engaging portion 102G1 on the +Z direction side is configured to catch on the side wall of the hole 12. This effectively prevents the waveguide device 100GM1 from falling out. Furthermore, even when the waveguide device 100GM1 is fixed to the hole 12 with an adhesive or the like, the waveguide device 100GM1 can be prevented from falling out of the hole 12 until the adhesive or the like hardens.

[0141] The waveguide device 100GM2 shown in FIG. 10B has an engagement portion 102G2 provided in a middle portion of the side wall 102G in the +Z direction and protruding radially outward from the side wall 102G. The engagement portion 102G2 engages with the side wall of the hole 12 when the waveguide device 100GM1 is inserted into the hole 12. As an example, three engagement portions 102G2 are provided at equal intervals in the circumferential direction in the middle portion of the side wall 102G in the Z direction. Each engagement portion 102G2 has a configuration in which three notches are formed in the middle portion of the side wall 102G in the Z direction, one in the circumferential direction and two in the Z direction, and the portions between the notches are bent radially outward. In FIG. 10B, the -Z direction side corresponds to the back side of the hole 12.

[0142] The end of the engaging portion 102G2 is located on the +Z direction side, so that even if an attempt is made to pull out the waveguide device 100GM2 from the hole 12, the end of the engaging portion 102G2 on the +Z direction side will catch on the side wall of the hole 12. Therefore, similar to the waveguide device 100GM1 shown in FIG. 10A, it is possible to effectively prevent the waveguide device 100GM2 from falling off.

[0143] The waveguide device 100GM3 shown in FIG. 10C has an engagement portion 102G3 provided in a middle portion of the side wall 102G in the +Z direction and protruding radially outward from the side wall 102G. When the waveguide device 100GM1 is inserted into the hole 12, the engagement portion 102G3 engages with the side wall of the hole 12. As an example, three engagement portions 102G3 are provided at equal intervals in the circumferential direction in a middle portion of the side wall 102G in the Z direction. Each engagement portion 102G3 has a configuration in which two cuts parallel to the Z direction are formed in a middle portion of the side wall 102G in the Z direction, and the portion between the two cuts is pushed radially outward. In FIG. 10C, the -Z direction side corresponds to the back side of the hole 12.

[0144] The engaging portion 102G3 has a central portion that protrudes outward most in the Z direction, so that the engaging portion 102G3 is configured to hook onto the side wall of the hole 12 both when inserting the waveguide device 100GM3 into the hole 12 and when pulling the waveguide device 100GM3 out of the hole 12. Therefore, similar to the waveguide devices 100GM1 and 100GM2 shown in Figures 10A and 10B, the waveguide device 100GM3 can be effectively prevented from falling off. Furthermore, the engaging portion 102G3 of the waveguide device 100GM3 has an inclined surface that protrudes radially outward when viewed from both the -Z direction and the +Z direction, which has the advantage of being easier to pull out from inside the hole 12 than the waveguide devices 100GM1 and 100GM2, and thus facilitating re-installation.

[0145] <Simulation results> FIG. 11A shows the characteristics of the gain of the circularly polarized radio wave emitted in the +Z direction by the detecting unit 100D versus the depth d of the hole 12. FIG. 11B shows the characteristics of the S11 parameter (S11 (dB)) of the antenna device 100A of the detecting unit 100D versus the depth d of the hole 12. FIG. 11C shows the characteristics of the bandwidth BW (MHz) of the antenna device 100A of the detecting unit 100D versus the depth d of the hole 12. The diameter of the hole is 200 mm, and the diameter of the waveguide device 100G is 195 mm.

[0146] 11A to 11C show the characteristics of a comparative installation structure, the installation structure of the embodiment, and the installation structure of a modified example of the embodiment. In the simulation, the operating frequency (resonant frequency) of antenna element 161 was set to 920 MHz.

[0147] <Gain of circularly polarized radio waves (Figure 11A)> In FIG. 11A, the horizontal axis represents the depth d (mm) of the hole 12, and the vertical axis represents the gain (dBic) of the circularly polarized radio wave.

[0148] As shown in FIGS. 7A to 7C, the installation structure for comparison is an installation structure using a washer 30. As shown in FIGS. 8A to 8C, the installation structure of the embodiment is an installation structure using a waveguide device 100G, which corresponds to the configuration of the detection device 100 of the embodiment. As shown in FIGS. 9A to 9C, the installation structure of the modified example of the embodiment is an installation structure using a waveguide device 100GM, which corresponds to the configuration of the detection device 100M of the embodiment.

[0149] As shown in FIG. 11A, in the installation structure for comparison, as the depth d of the hole 12 increased, the gain in the +Z direction decreased significantly. In contrast, in the installation structure of the embodiment and the installation structure of the modified example of the embodiment, even when the depth d of the hole 12 increased, the decrease in gain was small, and a gain of 4 dBic or more was obtained even when the depth d of the hole 12 was 120 mm. Also, the gain was slightly larger in the installation structure of the embodiment than in the modified example of the embodiment.

[0150] <S11 Parameter (FIG. 11B) and Bandwidth (FIG. 11C)> The S11 parameter (return loss) of the antenna element 161 as seen from point A (see FIG. 4A) was calculated. Also, the bandwidth in which the return loss is 10 dB or less was calculated.

[0151] No significant difference was observed in the S11 parameter and the bandwidth among the installation structure for comparison, the installation structure of the embodiment, and the installation structure of the modified example of the embodiment. Even in the installation structure for comparison, good S11 parameters and sufficient bandwidth were obtained, and it was confirmed that using the waveguide device 100G and the waveguide device 100GM did not affect the S11 parameter and the bandwidth.

[0152] From the results of FIGS. 11A to 11C, it was confirmed that stable communication can be achieved by using the waveguide device 100G or the waveguide device 100GM as long as the depth d of the hole 12 is up to about 120 mm.

[0153] <Average Gain of Circularly Polarized Radio Waves at 2.45 GHz (FIG. 12)> Fig. 12 shows the characteristics of the average gain of circularly polarized radio waves emitted in the +Z direction by detector 100D versus the depth d of hole 12 when the operating frequency of antenna element 161 is 2.45 GHz. In Fig. 12, the horizontal axis represents the depth d (mm) of hole 12, and the vertical axis represents the average gain (dBi) of the circularly polarized radio waves. Fig. 12 shows simulation results for a comparative installation structure and an installation structure according to a modified example of the embodiment.

[0154] In performing the simulation at 2.45 GHz, the size of each part (antenna element 161, etc.) of detector 100D was changed for 2.45 GHz. In addition, in the installation structure of the modified example of the embodiment, waveguide device 100GM (FIG. 9D) was used.

[0155] 12, in the comparative installation structure, the average gain in the +Z direction decreased significantly as the depth d of the hole 12 increased. In contrast, in the installation structure of the modified embodiment, the decrease in gain was small even when the depth d of the hole 12 increased, and a gain of approximately -2 dBi or more was obtained even when the depth d of the hole 12 was 200 mm.

[0156] <Effects> Waveguide device 100G of the present disclosure includes a waveguide provided inside hole 12 formed in the wall of a building, the waveguide having a cylindrical shape with a bottom or a cylindrical shape with openings at both ends, and antenna device 100A capable of radiating radio waves in the axial direction of the waveguide is disposed inside the waveguide with the waveguide provided inside hole 12. Since antenna device 100A is provided inside such a waveguide, good radiation characteristics of antenna device 100A can be obtained.

[0157] Therefore, it is possible to provide a waveguide device 100G that can achieve sufficient radiation characteristics of the antenna device 100A even when placed in close proximity to a metal member inside a hole 12 formed in a building.

[0158] Furthermore, the waveguide may be a cylindrical waveguide with a bottom, and may include a cylindrical side wall 102G, a disk-shaped bottom wall 101G provided at one of both ends of the side wall 102G, and an opening 101GA provided in the center of the bottom wall 101G. With the lock bolt 21 passed through the opening 101GA, the antenna device 100A is provided in the space surrounded by the bottom wall 101G and the side wall 102G, and therefore it is possible to provide a waveguide device 100G that can achieve sufficient radiation characteristics of the antenna device 100A.

[0159] The waveguide may be a cylindrical waveguide with openings at both ends, and may have a cylindrical sidewall 102GM. By using the washer 30, the antenna device 100A is provided in a space surrounded by the washer 30 and the sidewall 102G, so that a waveguide device 100GM that can achieve sufficient radiation characteristics of the antenna device 100A can be provided.

[0160] The waveguide may further include an engaging portion 102G1, 102G2, or 102G3 that is provided on the side wall 102G, protrudes radially outward from the side wall 102G, and engages with the inner surface of the hole 12. A waveguide device 100GM can be provided that has a waveguide that is unlikely to fall out of the hole 12 and can achieve sufficient radiation characteristics of the antenna device 100A.

[0161] Another waveguide device 100G of the present disclosure includes a waveguide section provided inside a hole 12 formed in a wall of a building, the waveguide section having a cylindrical shape with a bottom and an opening 101GA provided in the center of a disk-shaped bottom wall 101G, the hole 12 having a lock bolt 21 embedded in the bottom of the hole 12 and protruding into the hole 12, the waveguide section being provided inside the hole 12 with the lock bolt 21 inserted through the opening 101GA, and the waveguide section provided inside the hole 12 is provided with a strain body 120 fixed to the lock bolt 21 by a nut 22 that is inserted through the lock bolt 21 and fastened to the lock bolt 21, an antenna device 100A capable of radiating radio waves in the axial direction of the waveguide section, a strain sensor 130 that detects strain on the strain body 120 due to a fastening axial force applied by the lock bolt 21 and the nut 22 in the extension direction of the through hole, and a circuit section 180 that is connected to the antenna device 100A and the strain sensor 130 and performs wireless communication. Since the antenna device 100A is provided inside such a bottomed waveguide, the antenna device 100A can achieve good radiation characteristics.

[0162] Therefore, it is possible to provide a waveguide device 100G that can achieve sufficient radiation characteristics of the antenna device 100A even when placed in close proximity to a metal member inside a hole 12 formed in a building.

[0163] Another waveguide device 100GM of the present disclosure includes a waveguide section provided inside a hole 12 formed in a wall of a building, the waveguide section having a cylindrical shape with openings at both ends, a rock bolt 21 embedded in the bottom of the hole 12 and protruding into the hole 12 is provided in the hole 12, the waveguide section is provided inside the hole 12 with the rock bolt 21 inserted through the openings at both ends, and inside the waveguide section provided inside the hole 12 are disposed a strain body 120 that is fixed to the rock bolt 21 by a nut 22 that is inserted through the rock bolt 21 and fastened to the rock bolt 21, an antenna device 100A that can radiate radio waves in the axial direction of the waveguide section, a strain sensor 130 that detects strain in the strain body 120 due to a fastening axial force applied in the extension direction of the rock bolt 21 by the lock bolt 21 and the nut 22, and a circuit section 180 that is connected to the antenna device 100A and the strain sensor 130 and performs wireless communication. By utilizing the washer 30, the antenna device 100A is provided in a space surrounded by the washer 30 and the waveguide, and therefore good radiation characteristics of the antenna device 100A can be obtained.

[0164] Therefore, it is possible to provide a waveguide device 100GM that can achieve sufficient radiation characteristics of the antenna device 100A even when placed in close proximity to a metal member inside a hole 12 formed in a building.

[0165] The detection device 100 or 100M of the present disclosure includes any one of the above-described waveguide devices 100G or 100GM, an antenna device 100A, a flexure element 120 provided inside the waveguide, having a through hole through which a lock bolt 21 is inserted that is embedded in the bottom of the hole 12 and protrudes into the hole 12, and fixed to the lock bolt 21 by a nut 22 fastened to the lock bolt 21, a strain sensor 130 provided on the flexure element 120 and detecting strain of the flexure element 120 due to a fastening axial force applied in the extension direction of the lock bolt 21 by the lock bolt 21 and the nut 22, and a circuit unit 180 provided inside the waveguide, connected to the antenna device 100A and the strain sensor 130, and performing wireless communication. Since the antenna device 100A is provided inside such a waveguide, good radiation characteristics of the antenna device 100A can be obtained.

[0166] Therefore, it is possible to provide the detection device 100 or 100M that can realize sufficient radiation characteristics of the antenna device 100A even when the detection device 100 or 100M is placed in the vicinity of a metal member inside the hole 12 formed in a building.

[0167] Another detection device 100 or 100M of the present disclosure includes a waveguide device 100G or 100GM, an antenna device 100A, a strain sensor 130, and a circuit unit 180. Since the antenna device 100A is provided inside such a waveguide unit, good radiation characteristics of the antenna device 100A can be obtained.

[0168] Therefore, it is possible to provide the detection device 100 or 100M that can realize sufficient radiation characteristics of the antenna device 100A even when the detection device 100 or 100M is placed in the vicinity of a metal member inside the hole 12 formed in a building. [Explanation of symbols]

[0169] 12 holes 20 Fastening mechanism 21 Rock bolt (an example of a bolt) 22 Nut (example of nut part) 25 Hemispherical washer 30 washer 100, 100M detector 100A Antenna Unit 100D detector 100G, 100GM, 100GM1, 100GM2, 100GM3 waveguide device 101G, 102GM bottom wall (example of waveguide) 101GA aperture 102G Side wall (an example of a waveguide) 102G1, 102G2, 102G3 engaging part 110 cases 120 Strain body 130 Strain Sensor 145A Metal Pin 145B Metal Pin 150 wiring board 151 Ground Layer 152, 153 Power supply line 152, 154 Power supply line 160 Wiring board 161 Antenna element 170A coupled line 170B coupled line 180 Circuit section (example of communication section)

Claims

1. A waveguide provided inside a hole formed in a wall of a building, the waveguide having a cylindrical shape with a bottom or a cylindrical shape with openings at both ends, A waveguide device, wherein the waveguide is provided inside the hole, and an antenna device capable of radiating radio waves in the axial direction of the waveguide is disposed inside the waveguide.

2. the waveguide portion is a waveguide portion having a cylindrical shape with a bottom, a cylindrical side wall; a disk-shaped bottom wall provided at one of both ends of the side wall; a bottom wall opening provided in the center of the bottom wall; 2. The waveguide device of claim 1, wherein:

3. the waveguide portion is a cylindrical waveguide portion having openings at both ends, 10. The waveguide device of claim 1 having a cylindrical sidewall.

4. The waveguide device according to claim 3 , wherein the waveguide portion further includes an engagement portion provided on the side wall, protruding radially outward from the side wall, and engaging with an inner surface of the hole.

5. a waveguide provided inside a hole formed in a wall of a building, the waveguide having a cylindrical shape with a bottom and a bottom wall opening provided in a center of a disk-shaped bottom wall; The hole is provided with a bolt portion embedded in the bottom of the hole and protruding into the hole, the waveguide portion is provided inside the hole with the bolt portion inserted into the bottom wall opening, a waveguide device in which the following are disposed inside the waveguide provided inside the hole: a strain body that is fixed to the bolt portion by a nut portion that is inserted through the bolt portion and fastened to the bolt portion; an antenna device that can radiate radio waves in the axial direction of the waveguide portion; a strain sensor that detects strain on the strain body due to a fastening axial force applied in the extension direction of the bolt portion by the bolt portion and the nut portion; and a communication unit that is connected to the antenna device and the strain sensor and performs wireless communication.

6. The waveguide is provided inside a hole formed in a wall of a building, and includes a cylindrical waveguide having openings at both ends; The hole is provided with a bolt portion embedded in the bottom of the hole and protruding into the hole, the waveguide portion is provided inside the hole with the bolt portions inserted into the openings at both ends, a waveguide device in which the following are disposed inside the waveguide provided inside the hole: a strain body fixed to the bolt portion by a nut portion that is inserted through the bolt portion and fastened to the bolt portion; an antenna device that can radiate radio waves in the axial direction of the waveguide portion; a strain sensor that detects strain on the strain body due to a fastening axial force applied in the extension direction of the bolt portion by the bolt portion and the nut portion; and a communication unit that is connected to the antenna device and the strain sensor and performs wireless communication.

7. A waveguide device according to any one of claims 1 to 4; the antenna device; a strain generating body provided inside the waveguide, the strain generating body having a through hole through which a bolt portion embedded in a bottom of the hole and protruding into the hole is inserted, the strain generating body being fixed to the bolt portion by a nut portion fastened to the bolt portion; a strain sensor provided on the strain generating body and configured to detect a strain of the strain generating body due to a fastening axial force applied by the bolt portion and the nut portion in the extending direction of the through hole; a communication unit that is provided inside the waveguide unit, is connected to the antenna device and the strain sensor, and performs wireless communication; A detection device comprising:

8. a waveguide device according to claim 5 or claim 6; the antenna device; The strain element; The strain sensor; the communication unit; A detection device comprising:

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