JP7468891B2 - Measurement system and method - Google Patents

Description

The present invention relates to a measurement system and method capable of evaluating the electromagnetic wave transmission characteristics of a wide variety of covers, including covers for underground structures.

In recent years, there has been consideration of communicating between a device that generates radio waves (e.g., a wireless communication device) installed inside an underground structure and a device that receives radio waves (e.g., a wireless base station) installed on the ground through a cover for an underground structure (e.g., Patent Documents 1 and 2).
However, Patent Documents 1 and 2 do not disclose the evaluation of the radio wave transmission characteristics of a cover for an underground structure.

Japanese Patent Application Laid-Open No. 11-066484 JP 2018-067165 A

The present invention provides a measurement system and method capable of evaluating the electromagnetic wave transmission characteristics of a wide variety of covers, including covers for underground structures.

One aspect of the present invention is a measurement system that includes a housing that contains a device that generates electromagnetic waves, an opening provided in the housing, a lid that is removably attached to the opening, and a measurement device that measures the electromagnetic waves that pass through the opening covered by the lid to evaluate the electromagnetic wave transmission characteristics of the lid.

In this measurement system, a lid can be removably attached to an opening provided in a housing. Therefore, only the lid can be changed to a desired condition without changing conditions other than the lid (e.g., the shape, structure, material, etc. of the opening and the housing). Furthermore, the measurement device can measure electromagnetic waves passing through an opening covered by the lid. Therefore, the electromagnetic wave transmission characteristics of the lid can be appropriately evaluated, including differences in how the opening is covered due to differences in the shape, structure, material, etc. of the lid. Therefore, a measurement system can be provided that can evaluate the electromagnetic wave transmission characteristics of a wide variety of lids, including lids for underground structures, etc.

The lid may include a through hole passing through a position eccentric to a central axis of the lid, in which case it is preferable that the measurement system further comprises a rotation device for varying the rotation angle of the through hole relative to the central axis of the lid by rotating the housing about the central axis of the lid.
The lid may also include a non-circular through hole passing through the central axis of the lid, and in this case, it is preferable that the measurement system further includes a rotation device that changes the rotation angle of the through hole relative to the central axis of the lid by rotating the housing around the central axis of the lid.
According to this rotation device, by rotating the housing around the central axis of the lid, rather than around the central axis of the housing, the rotation angle (position, orientation) of the through hole relative to the central axis of the lid can be changed arbitrarily without being affected by the positional relationship of the openings provided in the housing. Therefore, it is possible to measure electromagnetic waves in a state where the position and orientation of the through hole are rotated 360 degrees around the central axis of the lid. Therefore, even if the lid includes a through hole that is eccentric from the central axis of the lid or a lid includes a non-circular through hole that passes through the central axis of the lid, the influence on the electromagnetic wave passing characteristics due to the difference in the position and orientation of the through hole can be appropriately evaluated.

The housing may include a conductive lid receiving member having an opening, and the lid receiving member may include a lid attachment portion for attaching the lid. By attaching the lid to the conductive lid receiving member, it becomes easier to reduce the effects of electromagnetic waves passing through the lid receiving member, making it easier to accurately evaluate the electromagnetic wave transmission characteristics of the lid itself.

The housing may include a dielectric position adjustment member that supports the conductive lid receiving member so that the position can be adjusted, and an electromagnetic wave shielding material arranged on the inner wall or outer wall of the position adjustment member. The effect on the electromagnetic wave transmission characteristics due to differences in the lid mounting position (e.g., the lid height, etc.) can be evaluated with a simple configuration.

The housing may include a dielectric lid receiving member having an opening, and an electromagnetic wave shielding material arranged on the inner wall or outer wall of the lid receiving member. By arranging the electromagnetic wave shielding material on the inner wall or outer wall of the lid receiving member, it becomes easier to reduce the effects of electromagnetic waves passing through the lid receiving member, making it easier to evaluate the electromagnetic wave passing characteristics of the lid itself with a simple configuration.

Another aspect of the present invention is a measurement method that includes removably attaching a lid to an opening provided in a housing that contains a device that generates electromagnetic waves, and measuring the electromagnetic waves that pass through the opening covered by the lid to evaluate the electromagnetic wave transmission characteristics of the lid.

The measuring step preferably includes measuring the electromagnetic waves while rotating the housing about its central axis so that the rotation angle relative to the central axis of a through hole that passes through a position eccentric from the central axis of the lid is changed, or includes measuring the electromagnetic waves while rotating the housing about its central axis so that the rotation angle relative to the central axis of a non-circular through hole that passes through the central axis of the lid is changed.

The present invention makes it possible to evaluate the electromagnetic wave transmission characteristics of a wide variety of covers, including covers for underground structures.

1 is a schematic diagram of a measurement system according to a first embodiment of the present invention; FIG. 11 is a schematic diagram showing a modification of the first embodiment. FIG. 4 is a schematic diagram of a measurement system according to a second embodiment of the present invention. FIG. 11 is a schematic plan view of a lid according to a second embodiment. FIG. 13 is a schematic diagram showing a modified example of the second embodiment. 4 is an example of an evaluation result of the electromagnetic wave transmission characteristics of a lid using the measurement system of FIG. 3.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In this specification, "cover" refers to manhole covers, large iron covers, and sewage manhole covers that close openings connecting underground buried objects, underground structural facilities, etc. in sewerage systems to the ground; openable and closable iron covers for common conduits, iron covers for power transmission, iron covers for power distribution that protect underground facility equipment and underground cables in the fields of electricity and communications; fire hydrant covers, water control valve covers, gate valve covers, air valve covers, gas pipe covers, water meter covers, etc. that function as opening and closing doors connecting buried conduits under the road surface in water supply and gas piping and their associated equipment to the ground (collectively referred to as "underground structure covers"), as well as covers such as gratings that cover rainwater manholes and gutters.
In addition, the term "electromagnetic wave" as used in this specification refers to a wave of energy that propagates through space while the electric and magnetic fields of radiation, light, radio waves, etc., interact with each other.

FIG. 1 shows an overview of a measurement system 10 according to a first embodiment of the present invention.
The measurement system 10 comprises a housing 12 that contains a device that generates electromagnetic waves (electromagnetic wave generating device) 11, an opening 13 provided in the housing 12, a lid 14 that is removably attached to the opening 13, and a measurement device 15 that measures the electromagnetic waves passing through the opening 13 covered by the lid 14 in order to evaluate the electromagnetic wave transmission characteristics of the lid 14.
This measurement system 10 is installed in a space that is unlikely to be affected by electromagnetic waves from the external environment (for example, a room 7 m deep, 3 m wide, and 3 m high, with electromagnetic wave shielding on all walls).

The electromagnetic wave generating device 11 contained within the housing 12 includes a battery-powered electromagnetic wave generator (not shown) that generates electromagnetic waves in the frequency band from 1 MHz to 6 GHz at regular frequency intervals (1 MHz, 5 MHz, or 10 MHz), and a dipole antenna (not shown) that radiates the electromagnetic waves.

The housing 12 is box-shaped with a circular opening 13 at the top, and is made of a conductive material. The opening 13 also includes a lid attachment portion 12-1. In this embodiment, the housing 12 is placed on a stand (desk) 16.

The lid 14 is circular and does not include a through hole, and is made of spheroidal graphite cast iron.

The measuring device 15 measures electromagnetic waves passing through the opening 13 covered by the lid 14 in order to evaluate the electromagnetic wave passing characteristics of the lid 14. In this embodiment, the measuring device 15 is disposed outside the housing 12 at a position 3 m (reference symbol LL1 in FIG. 1) away from the central axis C of the lid, with its height adjustable. In addition, an electromagnetic wave absorber 18 is disposed between the opening 13 and the measuring device 15.

As described above, in the measurement system 10 of this embodiment, the lid 14 can be detachably attached to the lid attachment portion 12-1 provided on the housing 12. Therefore, only the lid 14 can be changed to a desired condition without changing conditions other than the lid 14 (for example, the shape, structure, material, etc. of the opening 13 and the housing 12). Furthermore, the measurement device 15 can measure electromagnetic waves passing through the opening 13 covered by the lid 14.
Therefore, it is possible to appropriately evaluate the electromagnetic wave transmission characteristics of the cover 14, including differences in how the opening 13 is covered due to differences in the shape, structure, material, etc. of the cover 14. Therefore, it is possible to evaluate the electromagnetic wave transmission characteristics of a wide variety of covers, including covers for underground structures, etc.
In this specification, the term "electromagnetic wave passing characteristics" refers to a specific property obtained by quantitatively measuring, for example, the electric field intensity of electromagnetic waves passing through opening 13 of housing 12 covered by lid 14, which changes depending on differences in frequency and position of measuring device 15, and differences in how opening 13 is covered due to differences in the shape, structure, material, etc. of the lid.

In this embodiment, the housing 12 is conductive, but the housing 12 may be dielectric (e.g., plastic). In this case, as shown in FIG. 2, for example, it is preferable to place an electromagnetic wave shielding material 12c (e.g., an aluminum plate) on the inner wall of the dielectric housing 12. The inner wall of the housing 12 includes an inner surface 12-2 of the side wall and an inner surface 12-3 of the bottom wall. This makes it easier to reduce the effects of electromagnetic waves passing through the dielectric housing 12, and therefore makes it easier to evaluate the electromagnetic wave passing characteristics of the lid 14 itself with a simple configuration.
The electromagnetic wave shielding material 12c may be disposed on the outer wall of the dielectric housing 12. The outer wall of the housing 12 includes an outer surface 12-4 of a side wall and an outer surface 12-5 of a bottom wall.
In addition, in this embodiment, the opening 13 is provided in the upper part of the housing 12, but the opening 13 can also be provided in the side part of the housing 12.
In addition, although a circular opening 13 is provided in the housing 12 in this embodiment, for example, the opening 13 may be rectangular or other angular, and the housing 12 may be cylindrical rather than box-shaped, for example.
Also, the upper part of the housing 12 can be made into a lid receiving member having an opening 13 and a lid mounting portion 12-1.

FIG. 3 shows an overview of a measurement system 10A according to a second embodiment of the present invention.
The measurement system 10A includes a housing 12A that accommodates an electromagnetic wave generating device 11, an opening 13A provided in the housing 12A, a lid 14A that is removably attached to the opening 13A, a measuring device 15 that measures the electromagnetic waves passing through the opening 13A covered by the lid 14A to evaluate the electromagnetic wave transmission characteristics of the lid 14A, and a rotating device 17.
In this embodiment as well, the entire measurement system 10A is installed in a space that is unlikely to be affected by electromagnetic waves from the external environment.
In this embodiment, the electromagnetic wave generating device 11 and the measuring device 15 have the same configurations as those in the first embodiment.

Figure 4 is a schematic plan view of the lid 14A of this embodiment. This lid 14A is circular and is a rainwater inflow type that includes multiple arc-shaped through holes 14a that pass through the lid at positions eccentric to the central axis C, and is made of spheroidal graphite cast iron.

The housing 12A in this embodiment includes a conductive lid receiving member 12a having a circular opening 13A, and this lid receiving member 12a includes a lid mounting portion 12a-1 to which the lid 14A is attached. Note that in this embodiment, the lid receiving member 12a corresponds to a circular receiving frame that supports the lid for the underground structure, and is made of spheroidal graphite cast iron, the same as the lid 14A. That is, in this embodiment, the lid receiving member 12a is conductive.

The housing 12A of this embodiment includes a cylindrical position adjustment member 12b that supports the lid receiving member 12a in an adjustable position so that the effect on the electromagnetic wave transmission characteristics due to differences in the mounting position of the lid 14A (e.g., the height of the lid 14A) can be evaluated with a simple configuration, and an electromagnetic wave shielding material 12c that is arranged on the inner wall 12b-1 and lower end opening 12b-2 of the position adjustment member 12b to make it easier to reduce the effect of the electromagnetic waves passing through the position adjustment member 12b.
In this embodiment, the position adjustment member 12b is a replica of a manhole (a manhole) that is an underground structure, and is made of resin concrete. That is, in this embodiment, the position adjustment member 12b is dielectric.
The electromagnetic wave shielding material 12c is, for example, an aluminum plate. In this embodiment, the electromagnetic wave shielding material 12c is disposed on the inner wall 12b-1 and the lower end opening 12b-2 of the position adjustment member 12b, but the electromagnetic wave shielding material 12c may be disposed on the outer wall 12b-3 and the bottom surface 12b-4 including the lower end opening 12b-2 of the position adjustment member 12b.

The housing 12A is placed on a rotation device 17. The rotation device 17 rotates the housing 12A around the central axis C of the lid 14A, thereby changing the rotation angle of the through hole 14a with respect to the central axis C.
In this embodiment, the height H1 of the rotating device 17 is 800 mm, the height H2 of the position adjustment member 12b is 200 mm, and the height H3 of the lid receiving member 12a is 110 mm.

In this embodiment, the electromagnetic wave generator 11 is installed on the electromagnetic wave shielding material 12c at the lower end opening 12b-2 so as to be housed within the cylindrical position adjustment member 12b of the housing 12A.

In addition, the measurement system 10A of this embodiment includes a rotation device 17. By using this rotation device 17, the housing 12A is rotated around the central axis C of the lid 14A instead of around the central axis C1 of the housing 12A, and the rotation angle (position) of each through hole 14a with respect to the central axis C of the lid 14A can be changed arbitrarily without being affected by the shape of the housing 12A or the positional relationship of the opening 13A provided in the housing 12A. Therefore, it is possible to measure electromagnetic waves in a state where the positions of each through hole 14a are rotated 360 degrees around the central axis C of the lid 14A. Therefore, even if the lid 14A includes a plurality of through holes 14a eccentric from the central axis C, the influence on the electromagnetic wave passing characteristics due to the difference in the positions of each through hole 14a can be appropriately evaluated.
In this embodiment, the central axis C of the lid 14A (the central axis of the opening 13A), the central axis C1 of the housing 12A, and the central axis C2 of the rotation device 17 are all aligned, but the measurement system 10A can be applied even if the central axis C of the lid 14A (the central axis of the opening 13A) and the central axis C1 of the housing 12A are not aligned but are misaligned. In other words, as long as the central axis C of the lid 14A (the central axis of the opening 13A) and the central axis C2 of the rotation device 17 are aligned, the housing 12A can be rotated around the central axis C of the lid by the rotation device 17.
In addition, in this embodiment, the lid 14A is a type including a plurality of through holes 14a eccentric from the central axis C, but it may be a type including a non-circular through hole (e.g., C-shaped, I-shaped, arc-shaped, etc.) that passes through the central axis C of the lid. In this case as well, by aligning the rotation central axis C2 of the rotation device 17 with the central axis C of the lid and rotating the housing 12A around the central axis C of the lid by the rotation device 17, it is possible to appropriately evaluate the effect on the electromagnetic wave passing characteristics due to differences in the orientation of the through holes.

As described above, in the measurement system 10A of the present embodiment, the lid 14A can be detachably attached to the opening 13A provided in the housing 12A. Therefore, only the lid 14A can be changed to a desired condition without changing conditions other than the lid 14A (e.g., the shape, structure, material, etc. of the opening 13A and the housing 12A). Furthermore, the measurement device 15 can measure electromagnetic waves passing through the opening 13A covered by the lid 14A.
Therefore, it is possible to appropriately evaluate the electromagnetic wave transmission characteristics of the cover 14A, including the difference in how the opening 13A is covered due to the difference in the shape, structure, material, etc. of the cover 14A, and therefore it is possible to evaluate the electromagnetic wave transmission characteristics of a wide variety of covers, including covers for underground structures.

In this embodiment, the housing 12A includes a conductive lid receiving member 12a and a dielectric position adjustment member 12b, but the present invention is not limited to this and the position adjustment member 12b can be omitted. In this case, however, it is preferable to place an electromagnetic wave shielding material 12c at the lower end opening 12a-2 of the conductive lid receiving member 12a as shown in FIG. 5. The lid receiving member 12a can also be made dielectric. In this case, in order to easily reduce the influence of electromagnetic waves passing through the dielectric lid receiving member 12a, it is preferable to place an electromagnetic wave shielding material 12c on the inner wall or outer wall of the lid receiving member 12a in addition to the lower end opening of the lid receiving member 12a.
Further, in this embodiment, the position adjustment member 12b is dielectric and cylindrical, but the position adjustment member 12b may be dielectric and box-shaped like the housing 12 shown in FIG.

The materials of the lids 14, 14A, and the housing 12, the lid receiving member 12a, the position adjustment member 12b, and the electromagnetic wave shielding material 12c that constitute the housing 12A are not limited to those in the above-mentioned embodiment, and may be, for example, spheroidal graphite cast iron, steel, aluminum, etc., if conductive, or may be, for example, resin concrete, cement, rubber, plastic, etc., if dielectric.

As shown and explained in Figures 1 to 5, first, a lid 14 is removably attached to an opening 13 provided in a housing 12 that contains an electromagnetic wave generating device 11, and then, using a measuring device 15, the electromagnetic waves passing through the opening 13 covered by the lid 14 are measured in order to evaluate the electromagnetic wave passing characteristics of the lid 14, thereby making it possible to evaluate the electromagnetic wave passing characteristics of a wide variety of lids, including lids for underground structures.
In addition, if the lid 14A includes a through hole 14a that passes through a position eccentric from the central axis C of the lid 14A, when measuring the electromagnetic waves, the electromagnetic waves are measured while rotating the housing 12A around the central axis C of the lid 14A so that the rotation angle of the through hole 14a that passes through a position eccentric from the central axis C of the lid 14A with respect to the central axis C changes, thereby making it possible to properly evaluate the effect on the electromagnetic wave passage characteristics due to differences in the position of the through hole 14a, even in a type of lid that includes a through hole 14a that is eccentric from the central axis C of the lid 14A.
Furthermore, in the case where a non-circular through hole passing through the central axis C is included, when measuring the electromagnetic waves, the electromagnetic waves are measured while rotating the housing 12A around the central axis C of the lid 14A so that the rotation angle of the non-circular through hole passing through the central axis C of the lid 14A with respect to the central axis C changes, thereby making it possible to appropriately evaluate the effect on the electromagnetic wave passage characteristics due to differences in the orientation of the through hole, even in the case of a type of lid that includes a non-circular through hole passing through the central axis C of the lid 14A.

An example of the results of evaluating the electromagnetic wave passing characteristics of the lid 14A shown in FIG. 4 using the measurement system 10A shown in FIG. 3 is shown in FIG. 6. Specifically, the height of the measuring device 15 from the floor is set to 150 cm, the frequency of the radio waves emitted by the electromagnetic wave generating device 11 is set to 920 MHz, and the rotating device 17 is rotated 360 degrees at 5 degree intervals to measure the electric field strength of the radio waves, and a directional characteristic diagram (a graph showing the electric field strength at 360 degrees) is created. According to the directional characteristic diagram in FIG. 6, it can be seen that there is an angle at which the electric field strength is weak in the shape of the lid 14A shown in FIG. 4. In this way, the electromagnetic wave passing characteristics of a wide variety of lids can be evaluated.
In this example, the electromagnetic wave transmission characteristics are evaluated using a directional characteristic diagram, but the present invention is not limited to this.

10, 10A Measurement system 11 Device for generating electromagnetic waves (electromagnetic wave generating device)
12, 12A housing 12-1 lid attachment portion 12-2 inner surface of side wall 12-3 inner surface of bottom wall 12-4 outer surface of side wall 12-5 outer surface of bottom wall 12a lid receiving member 12a-1 lid attachment portion 12a-2 lower end opening 12b position adjustment member 12b-1 inner wall 12b-2 lower end opening 12b-3 outer wall 12b-4 bottom surface 12c electromagnetic wave shielding material 13, 13A opening 14, 14A lid 14a through hole 15 measuring device 16 stand (desk)
17 Rotating device 18 Electromagnetic wave absorber C Central axis of cover C1 Central axis of housing C2 Central axis of rotating device

Claims (5)

a housing for accommodating a device for generating electromagnetic waves;
An opening provided in the housing;
A cover for an underground structure, a rainwater catch basin, and a gutter that is detachably attached to the opening;
a measuring device for measuring the electromagnetic waves passing through the opening covered by the lid in order to evaluate an electromagnetic wave passing characteristic of the lid,
the lid includes a through hole extending through the lid,
the housing includes a conductive lid receiving member having the opening,
The lid receiving member includes a lid mounting portion for mounting the lid.
Measurement system. The housing includes a dielectric position adjustment member that supports the lid receiving member so that the position of the lid receiving member can be adjusted.
The measurement system according to claim 1 , further comprising an electromagnetic wave shielding material disposed on an inner wall or an outer wall of the position adjustment member. a housing for accommodating a device for generating electromagnetic waves;
An opening provided in the housing;
A cover for an underground structure, a rainwater catch basin, and a gutter that is detachably attached to the opening;
a measuring device for measuring the electromagnetic waves passing through the opening covered by the lid in order to evaluate an electromagnetic wave passing characteristic of the lid,
the lid includes a through hole extending through the lid,
The housing includes a dielectric lid receiving member having the opening;
and an electromagnetic wave shielding material disposed on an inner wall or an outer wall of the lid receiving member.
Measurement system. The through hole is a through hole that passes through a position eccentric to a central axis of the lid,
The measurement system according to claim 1 , further comprising a rotation device configured to rotate the housing around the central axis to change a rotation angle of the through hole relative to the central axis. The through hole is a non-circular through hole passing through a central axis of the lid,
The measurement system according to claim 1 , further comprising a rotation device configured to rotate the housing around the central axis to change a rotation angle of the through hole relative to the central axis.

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