Patent Description:
Conventionally, in areas where a multitude of buildings, condominium buildings, telephone poles, and the like are present, radio base stations are installed on these buildings, whereas in areas where these buildings are not present (for example, areas around parks or sports grounds), steel tower-like radio base stations are installed. However, it is often the case that in the above-mentioned areas where these buildings are not present, consideration for landscapes is required, and inconspicuously installing the radio base stations is demanded.

As the conventional technology that inconspicuously installs the radio base stations, a manhole type antenna in which a radio base station is installed in a manhole has been known (PTL <NUM>).

<CIT> discloses a manhole cover, comprising a wall portion that defines a space in which a transmit/receive antenna is disposed has such a slope as to expand the space from a base station unit toward an upper surface portion of the manhole cover, and an angle of slope varies depending on the dimensions of a service area. Also, when the existence of the obstructive on the manhole cover is detected by use of a pressure sensor or an electric wave sensor, the control of the communication operation of a mobile station is switched to another base station without calculating or processing an electric field intensity in the base station.

<CIT> discloses a wireless base station antenna, including an antenna body and a cover body, the cover body including steel structure framework and the glass steel shell installed on steel structure framework. The steel structure framework passes through a bolt fastening on holding surface or support frame, holding surface or support frame are fixed in on the building, the glass steel shell passes through the bolt fastening on steel structure framework, the antenna body is installed in glass steel shell.

<CIT> discloses a device comprising a cable retainer for retaining cable. The device is provided with cable retaining parts, which have elasticity in the axial direction and the diametrical direction and are formed into spirals and retain cables at a hollow portion extending in the axial direction, and mounting parts, which are provided on both ends of the cable retaining parts in the axial direction and the cable retainers are mounted at prescribed positions of the device.

In a case of the manhole type antenna, since a distance between a human body and an antenna element is short, if in order to widen a communication area, an electric field strength of radio waves is strengthened, it is likely that the specified radio wave protection guidelines are not satisfied. However, as for the manhole type antenna in the conventional technology, no consideration is paid to the radio wave protection guidelines.

An object of the present invention is to provide an antenna apparatus of an underground embedded type which allows adjustment for satisfying the radio wave protection guidelines to be made.

The present invention provides an antenna apparatus, in accordance with claim <NUM>.

The present invention also provides a radio base station, in accordance with claim <NUM>.

According to the present invention, adjustment for satisfying the radio wave protection guidelines can be made for the antenna apparatus of an underground embedded type.

First, with reference to <FIG>, an outline of antenna apparatus <NUM> of an underground embedded type will be described.

Antenna apparatus <NUM> is installed in manhole <NUM> formed under ground <NUM>. On a side surface of manhole <NUM>, side wall section <NUM> is provided. Manhole cover <NUM> is fitted to a groove formed in rim section <NUM> on a side of ground surface <NUM> of side wall section <NUM> and covers manhole <NUM>.

Manhole <NUM> is a vertical hole formed under ground <NUM> so as to allow a person to come in and go out from and to the ground to manage piping of water-and-sewage pipes, gas conduits, or the like, wiring of communication cables, power distribution of electric cables, or the like. Note, however, that manhole <NUM> in which antenna apparatus <NUM> is installed is not necessarily required to have a size allowing a person to come therein and go thereout and as with the so-called handhole, may be a hole having a size which does not allow a person to come therein and go thereout. In addition, antenna apparatus <NUM> may be installed in manhole <NUM> (or a handhole) for the existing equipment and may be installed in a hole (or a dip or the like) newly formed for antenna apparatus <NUM>. In other words, antenna apparatus <NUM> may be installed in any hole formed under ground <NUM>. Therefore, manhole cover <NUM> is also merely one example of a cover that covers a hole formed under ground <NUM> and may be any cover.

As shown in <FIG>, antenna apparatus <NUM> is placed in the ground inside manhole <NUM>. Alternatively, antenna apparatus <NUM> may be installed so as to be suspended inside manhole <NUM>. In this case, antenna apparatus <NUM> includes arm sections (not shown), and the arm sections are hooked onto rim section <NUM> of side wall section <NUM>.

Antenna apparatus <NUM> includes supporting section <NUM>, antenna base <NUM>, antenna elements <NUM>, antenna angle adjustment mechanisms <NUM>, and antenna height adjustment mechanisms <NUM>.

Supporting section <NUM> supports antenna base <NUM> via antenna height adjustment mechanisms <NUM>. Antenna base <NUM> retains antenna elements <NUM> via antenna angle adjustment mechanisms <NUM>.

Antenna elements <NUM> connects with a main body of a base station via connector cables <NUM> and transmits and receives radio waves to and from mobile terminal <NUM>. The base station is, for example, a base station of a wireless LAN (Wi-Fi) or a base station of LTE, <NUM>, or the like.

Each of the antenna angle adjustment mechanisms <NUM> adjusts an angle of each of antenna elements <NUM>. Note that details of antenna angle adjustment mechanisms <NUM> will be described later. Antenna height adjustment mechanisms <NUM> adjust a height (a distance up to manhole cover <NUM>) of antenna base <NUM>. Note that an example of adjustment by antenna height adjustment mechanisms <NUM> will be described later.

Next, radio wave protection guidelines will be described.

In the radio wave protection guidelines, with respect to a location where a human body is present, for example, conditions that "an average of power densities at all measurement points shall not exceed <NUM>,<NUM>µW/cm<NUM>" and that "any of the power densities at all measurement points shall not exceed <NUM>,<NUM>µW/cm<NUM>" are specified.

As conventionally, when a radio base station is installed in a high place, since a distance between human body (user) <NUM> and antenna apparatus <NUM> is comparatively long, it is not so difficult to obtain a desired communication distance (or a communication area) while the conditions in the radio wave protection guidelines are satisfied. However, in a case of antenna apparatus <NUM> of an underground embedded type, as shown in <FIG>, human body <NUM> sometimes passes immediately above antenna apparatus <NUM>, and since a distance between human body <NUM> and antenna apparatus <NUM> is comparatively short, in order to lengthen the communication distance as long as possible while the conditions in the radio wave protection guidelines are satisfied, delicate adjustment is required.

Therefore, in the present embodiment, in order to allow the adjustment as mentioned above to be easily performed on an installation site, antenna apparatus <NUM> which includes antenna angle adjustment mechanisms <NUM> and antenna height adjustment mechanisms <NUM> is provided.

Next, an example of adjusting an antenna height by antenna height adjustment mechanisms <NUM> will be described.

For example, when each measured power density exceeds each of the conditions in the radio wave protection guidelines, a distance from antenna elements <NUM> to manhole cover <NUM> is made long by antenna height adjustment mechanisms <NUM> (that is, antenna elements <NUM> are located away from ground surface <NUM>). This allows an electromagnetic field strength at measurement points above antenna apparatus <NUM> to be weakened.

On the other hand, when each measured power density sufficiently satisfies each of the conditions in the radio wave protection guidelines, the distance from antenna elements <NUM> to manhole cover <NUM> is made short by antenna height adjustment mechanisms <NUM> (that is, antenna elements <NUM> are made to approach ground surface <NUM>). This allows the electromagnetic field strength at the measurement points above antenna apparatus <NUM> to be strengthened and a communication distance to be lengthened. Note that a specific configuration example of antenna height adjustment mechanisms <NUM> will be described in Embodiments <NUM> to <NUM>.

Next, with reference to <FIG>, antenna angle adjustment mechanisms <NUM> will be described.

Each of antenna angle adjustment mechanisms <NUM> is a mechanism which is operable, as shown in <FIG>, to rotate each of antenna elements <NUM> at <NUM> degrees in a horizontal direction with respect to a principal surface of antenna base <NUM> and as shown in <FIG>, to rotate each of antenna elements <NUM> at <NUM> degrees in a vertical direction with respect to the principal surface of antenna base <NUM>.

In addition, as shown in <FIG>, in the vicinity of lower portions of antenna angle adjustment mechanisms <NUM> in antenna base <NUM>, holes <NUM> are formed so as to allow antenna elements <NUM> to rotate in the vertical direction and to allow connector cables <NUM> extending from antenna elements <NUM> to lead to below antenna base <NUM>. A shape of each of holes <NUM> is, for example, a fan-shape with a central angle of <NUM> degrees.

Note that each of antenna elements <NUM> is housed in an antenna case and is thereby protected from foreign powder dust, rain water, and the like. In this case, each of antenna angle adjustment mechanisms <NUM> may be a mechanism which is operable to rotate the antenna case which houses each of antenna elements <NUM>.

Next, with reference to <FIG>, radio wave radiation patterns (a simulation result) obtained when the angles of two antenna elements (sleeve antennas) <NUM> installed on antenna base <NUM> have been adjusted will be described. Note that a plurality of radio wave radiation patterns shown in <FIG> are in a case in which frequencies of radio waves are <NUM>, <NUM>, <NUM>, and <NUM>.

<FIG> shows radio wave radiation patterns in a position with a distance of <NUM> in a Z axis direction away from antenna elements <NUM>, exhibited when as indicated by disposition G1, two antenna elements <NUM> were separated with a distance of <NUM> from each other and angles were adjusted such that main axes of two antenna elements <NUM> were in parallel with an X axis.

<FIG> shows radio wave radiation patterns in a position with a distance of <NUM> in the Z axis direction away from antenna elements <NUM>, exhibited when as indicated by disposition G2, two antenna elements <NUM> were separated with the distance of <NUM> from each other and angles were adjusted such that the main axes of two antenna elements <NUM> were in parallel with a Z axis.

<FIG> shows radio wave radiation patterns in a position with the distance of <NUM> in the Z axis direction away from antenna elements <NUM>, exhibited when as indicated by disposition G3, two antenna elements <NUM> were separated with the distance of <NUM> from each other and angles were adjusted such that a main axis of one of antenna elements <NUM> was in parallel with the X axis and a main axis of the other of antenna elements <NUM> was in parallel with the Z axis.

In <FIG>, in a diagram of a YZ plane, a horizontal axis indicates a Y axis direction, a vertical axis indicates a Z axis direction. In a diagram of a ZX plane, a horizontal axis indicates an X axis direction and a vertical axis indicates a Z axis direction. In a diagram of an XY plane, a horizontal axis indicates a Y axis direction and a vertical axis indicates an X axis direction.

By referencing radio wave radiation patterns of all of the YZ planes and the ZX planes in <FIG>, it is seen that in accordance with an increase in a distance from antenna elements <NUM> in the Z axis direction, an electric field strength of radio waves decreases. In addition, it is seen that even when the frequencies of radio waves are different from one another, the above-mentioned tendency is the same.

In addition, by comparing radio wave radiation patterns of the XY planes in <FIG>, it is seen that when a wide communication area is formed evenly in the X axis direction and the Y axis direction from a center of antenna apparatus <NUM>, it is preferable that antenna angle adjustment mechanisms <NUM> are adjusted such that antenna axes of two antenna elements <NUM> are in parallel with the Z axis.

Note, however, that the above-mentioned <FIG> are referenced merely to show that by changing the angles of antenna elements <NUM>, the radio wave radiation patterns change, and the simulation result shown in <FIG> does not limit the invention at all.

As described above, in Embodiment <NUM>, antenna apparatus <NUM> of an underground embedded type includes antenna angle adjustment mechanisms <NUM> which adjust the angles of antenna elements <NUM> and antenna height adjustment mechanisms <NUM> which adjust the height of antenna base <NUM>. Thus, a worker can easily perform, on the installation site of antenna apparatus <NUM>, the adjustment to lengthen the communication distance as long as possible while the conditions in the radio wave protection guidelines are satisfied.

Next, with reference to <FIG> and <FIG>, a configuration of antenna apparatus 10A according to Embodiment <NUM> will be described. <FIG> is a sectional side view of antenna apparatus 10A. <FIG> is a plan view of intermediate member <NUM> which is a component of antenna apparatus 10A, viewed from above. Note that components in common with those in Embodiment <NUM> are denoted by the same reference signs, and the description for the components in common therewith will be omitted.

As with antenna apparatus <NUM>, antenna apparatus 10A includes antenna base <NUM>, antenna elements <NUM>, and antenna angle adjustment mechanisms <NUM>. In addition, antenna apparatus 10A further includes pedestal <NUM>, leg sections <NUM>, supporting columns <NUM>, height adjusters <NUM>, intermediate member <NUM>, and buffer sections 25A.

Pedestal <NUM>, leg sections <NUM>, and supporting columns <NUM> in antenna apparatus 10A correspond to one example of supporting section <NUM> of antenna apparatus <NUM>. Height adjusters <NUM> and intermediate member <NUM> in antenna apparatus 10A correspond to one example of antenna height adjustment mechanisms <NUM>. In addition, height adjusters <NUM> may be called a positioning section which determines a position where antenna base <NUM> is attached.

Pedestal <NUM> is provided with a plurality of leg sections <NUM> on a lower surface thereof and by grounding leg sections <NUM> on a ground surface inside manhole <NUM>, is disposed horizontally with respect to the ground surface.

Supporting columns <NUM> are fixed vertically with respect to pedestal <NUM> and extend upward. <FIG> shows an example in which the number of supporting columns <NUM> is four. Note, however, that the present embodiment is not limited thereto, and the number thereof may be any number as long as the number thereof is two or more.

Height adjusters <NUM> are tools which can be attached in any positions (at heights) of supporting columns <NUM>. Each of height adjusters <NUM> is constituted of cylindrical section <NUM> and fixture <NUM>. An inner diameter of cylindrical section <NUM> is larger than an outer diameter of each of supporting columns <NUM>. Each of supporting columns <NUM> is inserted into cylindrical section <NUM>. Fixture <NUM> is, for example, a screw. By tightening fixture <NUM> (the screw), cylindrical section <NUM> is fixed to each of supporting columns <NUM>. By loosening fixture <NUM> (the screw), cylindrical section <NUM> becomes movable in upward and downward directions along supporting columns <NUM>. Note, however, that fixture <NUM> is not limited to the screw type, and may be a push-type, a slide-type, or the like. Note that when fixture <NUM> has a structure projecting in a vertical direction with respect to an axis of each of supporting columns <NUM>, in order to cause no hindrance when antenna apparatus 10A is installed in manhole <NUM>, it is preferable that fixture <NUM> is disposed so as to project in a direction toward a center of manhole <NUM> (that is, inwardly).

As shown in <FIG>, intermediate member <NUM> is constituted of circular ring section <NUM>, cylindrical sections <NUM>, reinforcing plates <NUM>, and brackets <NUM>. Circular ring section <NUM> is of a circular ring shape, and a diameter thereof is smaller than a diameter of manhole <NUM> and larger than a diameter of antenna base <NUM>. An inner diameter of each of cylindrical sections <NUM> is larger than an outer diameter of each of supporting columns <NUM>. Each of cylindrical sections <NUM> is welded to an inside of circular ring section <NUM>. The number of cylindrical sections <NUM> is the same as the number of supporting columns <NUM>. Reinforcing plates <NUM> are welded such that the two plates are crossed at a center point of circular ring section <NUM>. Further, reinforcing plates <NUM> are welded to cylindrical sections <NUM> in edge portions thereof. Brackets <NUM> are welded to reinforcing plates <NUM> in the vicinity of cylindrical sections <NUM>. In addition, in brackets <NUM>, attaching holes <NUM> are formed.

As shown in <FIG>, intermediate member <NUM> is disposed above height adjusters <NUM>. In other words, each of supporting columns <NUM> is inserted into each of cylindrical sections <NUM> of intermediate member <NUM>. Note that intermediate member <NUM> is reinforced by reinforcing plates <NUM> so as not to be a mere flat plate because rain water and the like is prevented from accumulating in intermediate member <NUM>.

Each of buffer sections 25A is fixed by a screw or the like to a portion of each of attaching holes <NUM> of brackets <NUM> of intermediate member <NUM>. In <FIG>, an example in which the number of buffer sections 25A is four is shown. Note, however, that the present embodiment is not limited thereto, and the number thereof may be any number as long as the number thereof is three or more. In addition, in <FIG>, a case in which each of buffer sections 25A is a spring is shown. However, the present embodiment is not limited thereto, and each of buffer sections 25A may be rubber, a cushion, or the like.

Four rods <NUM> are welded to a seating surface of antenna base <NUM>. In addition, with buffer sections 25A placed on brackets <NUM>, rods <NUM> are inserted into buffer sections 25A and attaching holes <NUM>. Nuts are attached from tip ends of rods <NUM> as stoppers. Thus, antenna base <NUM> is fixed to intermediate member <NUM> and is positioned in a height direction by a biasing force of each of buffer sections 25A.

By employing the configuration of antenna apparatus 10A, positions of height adjusters <NUM> are changed, thereby allowing positions (heights) of intermediate member <NUM>, buffer sections 25A, and antenna base <NUM> to be changed.

Specifically, by moving height adjusters <NUM> downward, the position of antenna base <NUM> can be moved downward (in a direction away from manhole cover <NUM>). Conversely, by moving height adjusters <NUM> upward, the position of antenna base <NUM> can be moved upward (in a direction approaching manhole cover <NUM>). Thus, a worker can adjust an electromagnetic field strength of radio waves on an installation site of antenna apparatus 10A so as to satisfy the conditions in the radio wave protection guidelines.

In addition, by placing antenna base <NUM> on buffer sections 25A, vibration which is received by pedestal <NUM>, supporting columns <NUM>, intermediate member <NUM>, and the like from an outside can be inhibited from directly being transmitted to antenna base <NUM>. Thus, displacement of the positions (for example, the angles) of antenna elements <NUM> installed on antenna base <NUM>, which is caused by the vibration from the outside, slipping-off of connector cables <NUM> of antenna elements <NUM>, and the like can be inhibited.

Note that height adjusters <NUM> may be configured to be fixed only in some predetermined positions (at heights). For example, height adjusters <NUM> may be configured such that a hole is formed in a predetermined position of each of supporting columns <NUM>, a hole is formed on a side surface of cylindrical section <NUM>, and fixture <NUM> (a pin) is inserted into the hole of cylindrical section <NUM> and the hole of each of supporting columns <NUM>.

As described above, in Embodiment <NUM>, the configuration of antenna apparatus 10A of an underground embedded type is adopted in which intermediate member <NUM> is placed above height adjusters <NUM> provided for supporting columns <NUM> and antenna base <NUM> is placed above intermediate member <NUM>. Thus, since a worker can easily change attaching positions of height adjusters <NUM> on the installation site of antenna apparatus 10A, a height of antenna base <NUM> can be easily adjusted.

Next, with reference to <FIG>, a configuration of antenna apparatus 10B according to Embodiment <NUM> will be described. <FIG> is a sectional side view of antenna apparatus 10B. Note that components of antenna apparatus 10B in <FIG> which are in common with those in antenna apparatus 10A shown in <FIG> are denoted by the same reference signs, and the description for the components in common therewith will be omitted.

As with antenna apparatus 10A, antenna apparatus 10B includes antenna elements <NUM>, antenna angle adjustment mechanisms <NUM>, pedestal <NUM>, and leg sections <NUM>. In addition, antenna apparatus 10B includes antenna base 12B and buffer section 25B. Antenna base 12B is different from antenna base <NUM> of antenna apparatus 10A in that screw hole <NUM> is formed in a central portion thereof. Buffer section 25B is different from each of buffer sections 25A of antenna apparatus 10A in that buffer section 25B is a spring having a through hole formed therein. In addition, antenna apparatus 10B includes first supporting column <NUM> and second supporting column <NUM>.

Pedestal <NUM>, leg sections <NUM>, first supporting column <NUM>, and second supporting column <NUM> in antenna apparatus 10B correspond to one example of supporting section <NUM> of antenna apparatus <NUM>. Screw hole <NUM> formed in a central portion of antenna base 12B and screw groove <NUM> threaded on at least one portion of second supporting column <NUM> in antenna apparatus 10B correspond to one example of antenna height adjustment mechanisms <NUM>.

First supporting column <NUM> is fixed vertically with respect to a principal surface of pedestal <NUM> in a central portion of an upper surface of pedestal <NUM> and extends upward. In addition, first supporting column <NUM> is provided with stopper <NUM> having a surface vertical with respect to a main axis of first supporting column <NUM>.

Buffer section 25B has the through hole formed in a central portion thereof. First supporting column <NUM> is inserted into the through hole of buffer section 25B and a lower end of buffer section 25B is placed on stopper <NUM>.

Second supporting column <NUM> is of a cylindrical shape allowing first supporting column <NUM> to be inserted thereinto, and first supporting column <NUM> is inserted into the cylinder. Second supporting column <NUM> is supported to first supporting column <NUM>, with a lower end of second supporting column <NUM> contacting an upper end of buffer section 25B.

In addition, in order to avoid rotation of second supporting column <NUM> with respect to first supporting column <NUM>, first supporting column <NUM> and second supporting column <NUM> are provided with rotation preventing mechanisms. As the rotation preventing mechanisms, for example, a configuration is adopted in which pin <NUM> attached on second supporting column <NUM> is fitted into a cutout (not shown) formed in first supporting column <NUM>.

By employing the configuration of antenna apparatus 10B, since screw hole <NUM> of antenna base 12B and screw groove <NUM> of second supporting column <NUM> are screwed with each other, by rotating antenna base 12B, a height of antenna base 12B can be changed.

For example, by rotating antenna base 12B clockwise, a position of antenna base 12B can be moved downward (in a direction away from manhole cover <NUM>)). Conversely, by rotating antenna base 12B counterclockwise, the position of antenna base 12B can be moved upward (in a direction approaching manhole cover <NUM>). Thus, on an installation site of antenna apparatus 10B, an electromagnetic field strength of radio waves can be adjusted so as to satisfy the conditions in the radio wave protection guidelines.

In addition, by providing buffer section 25B between first supporting column <NUM> and second supporting column <NUM>, vibration which is received by pedestal <NUM> and first supporting column <NUM> from an outside can be inhibited from directly being transmitted to antenna base 12B. Thus, displacement of positions (for example, angles) of antenna elements <NUM> installed on antenna base 12B, which is caused by the vibration from the outside, slipping-off of connector cables <NUM> of antenna elements <NUM>, and the like can be inhibited.

In addition, second supporting column <NUM> may be provided with a scale (not shown) in a height direction. Thus, even without separately using a surveying tool, the height of antenna base 12B can be visually checked. In other words, on the installation site thereof, adjustment of an electromagnetic field strength of radio waves can be further facilitated.

Note that in the present embodiment, instead of screw hole <NUM> of antenna base 12B and screw groove <NUM> of second supporting column <NUM> as antenna height adjustment mechanisms <NUM>, other configuration may be adopted. For example, height adjuster <NUM> illustrated in <FIG> is attached to second supporting column <NUM>. In the central portion of antenna base 12B, instead of the screw hole, a through hole is formed, second supporting column <NUM> is inserted into the through hole, and antenna base <NUM> is place above height adjuster <NUM>. Also by adopting this configuration, by adjusting a position of attaching height adjuster <NUM>, a height of antenna base 12B can be adjusted.

As described above, in Embodiment <NUM>, the configuration of antenna apparatus 10B of an underground embedded type is adopted in which screw hole <NUM> of antenna base 12B and screw groove <NUM> of second supporting column <NUM> are screwed with each other. Thus, a worker rotates antenna base 12B on the installation site of antenna apparatus 10B, thereby allowing the height of antenna base 12B to be easily adjusted.

Next, with reference to <FIG>, a configuration of antenna apparatus 10C according to Embodiment <NUM> will be described. <FIG> is a sectional side view of antenna apparatus 10C. Note that components of antenna apparatus 10C in <FIG> which are in common with those in antenna apparatus 10B shown in <FIG> are denoted by the same reference signs, and the description for the components in common therewith will be omitted.

As with antenna apparatus 10B, antenna apparatus 10C includes antenna elements <NUM>, antenna angle adjustment mechanisms <NUM>, pedestal <NUM>, and leg sections <NUM>. In addition, antenna apparatus 10C includes antenna base 12C and buffer section 25C. Antenna base 12C is different from antenna base 12B of antenna apparatus 10B in that through hole <NUM> is formed in a central portion thereof, instead of screw hole <NUM> and in that buffer section 25C is rubber or a cushion. In addition, antenna apparatus 10C includes supporting column <NUM> and intermediate member <NUM>.

Pedestal <NUM>, leg sections <NUM>, and supporting column <NUM> in antenna apparatus 10C correspond to one example of supporting section <NUM> of antenna apparatus <NUM>. Intermediate member <NUM>, screw hole <NUM> formed in the central portion of intermediate member <NUM>, and screw groove <NUM> threaded on at least one portion of supporting column <NUM> in antenna apparatus 10C correspond to one example of antenna height adjustment mechanisms <NUM>.

Supporting column <NUM> is fixed vertically with respect to pedestal <NUM> in a central portion of an upper surface of pedestal <NUM> and extends upward.

Screw hole <NUM> of intermediate member <NUM> is screwed with screw groove <NUM> of supporting column <NUM>. In addition, on an upper surface of intermediate member <NUM>, buffer section 25C is provided. Note that although in <FIG>, a case in which intermediate member <NUM> is smaller than antenna base 12C is shown, the present embodiment is not limited thereto, and a size of intermediate member <NUM> may be the same as a size of antenna base 12C or be the size or more of antenna base 12C.

Supporting column <NUM> is inserted into through hole <NUM> in the central portion of antenna base 12C and antenna base 12C is placed above intermediate member <NUM>.

By employing the configuration of antenna apparatus 10C, since screw groove <NUM> of supporting column <NUM> and screw hole <NUM> of intermediate member <NUM> are screwed with each other, by rotating intermediate member <NUM>, heights of intermediate member <NUM> and antenna base 12C placed above intermediate member <NUM> can be changed.

For example, by rotating intermediate member <NUM> clockwise, a position of antenna base 12C can be moved downward (in a direction away from manhole cover <NUM>). Conversely, by rotating intermediate member <NUM> counterclockwise, the position of antenna base <NUM> can be moved upward (in a direction approaching manhole cover <NUM>). Thus, on an installation site of antenna apparatus 10C, an electromagnetic field strength of radio waves can be adjusted so as to satisfy the conditions in the radio wave protection guidelines.

In addition, by providing buffer section 25C on the upper surface of intermediate member <NUM>, vibration which is received by leg sections <NUM>, supporting column <NUM>, and intermediate member <NUM> from an outside can be inhibited from directly being transmitted to antenna base 12C. Thus, displacement of positions (for example, angles) of antenna elements <NUM> installed on antenna base 12C, which is caused by the vibration from the outside, slipping-off of connector cables <NUM> of antenna elements <NUM>, and the like can be inhibited.

Note that in order for antenna base 12C not to freely rotate around supporting column <NUM> due to the vibration or the like, a rotation preventing mechanism (not shown) is provided. As the rotation preventing mechanism, for example, a configuration is adopted in which a hole (not shown) is formed in a portion of antenna base 12C contacting intermediate member <NUM>, intermediate member <NUM> has a projecting section (not shown) extending upward, and the projecting section is inserted into the hole of antenna base 12C. Note that antenna base <NUM> may be provided with a plurality of holes formed at equal intervals on a concentric circle. Thus, antenna base 12C can be fixed in a position with a desired rotational angle or angles.

In addition, supporting column <NUM> may be provided with a scale (not shown) in a height direction. Thus, even without separately using a surveying tool, the height of antenna base 12C can be visually checked. In other words, on the installation site thereof, adjustment of an electromagnetic field strength of radio waves can be further facilitated.

As described above, in Embodiment <NUM>, the configuration of antenna apparatus 10C of an underground embedded type is adopted in which screw hole <NUM> of intermediate member <NUM> and screw groove <NUM> of supporting column <NUM> are screwed with each other and antenna base 12C is placed above intermediate member <NUM>. Thus, on a work site of antenna apparatus 10C, a worker rotates intermediate member <NUM>, thereby determines a height, and thereafter, places antenna base 12C on intermediate member <NUM>, thereby allowing the height of antenna base 12C to be easily adjusted.

Next, with reference to <FIG>, a configuration of antenna apparatus 10D according to Embodiment <NUM> will be described. <FIG> is a sectional side view of antenna apparatus 10D. Note that components of antenna apparatus 10D in <FIG> which are in common with those in antenna apparatus 10B shown in <FIG> are denoted by the same reference signs, and the description for the components in common therewith will be omitted.

As with antenna apparatus 10B, antenna apparatus 10D includes antenna elements <NUM> and antenna angle adjustment mechanisms <NUM>. In addition, antenna apparatus 10D includes antenna base 12D, handle section <NUM>, shaft section <NUM>, bearing section <NUM>, and guide sections <NUM>. Antenna base 12D is different from antenna base 12B in that on a side surface thereof, a projecting section <NUM> is provided.

Shaft section <NUM> in antenna apparatus 10D corresponds to one example of supporting section <NUM> of antenna apparatus <NUM>. Screw hole <NUM> of antenna base 12D and screw groove <NUM> threaded on at least one portion of shaft section <NUM> in antenna apparatus 10D correspond to one example of antenna height adjustment mechanisms <NUM>.

Handle section <NUM> is horizontally disposed below manhole cover <NUM> so as to face manhole cover <NUM>.

One end of shaft section <NUM> is welded to a central portion of handle section <NUM> vertically with respect to handle section <NUM>, and shaft section <NUM> extends upward.

Bearing section <NUM> is provided in a central portion of a lower surface of manhole cover <NUM> and receives rotatably the other end of shaft section <NUM> (that is, an end which is not welded to handle section <NUM>).

Screw hole <NUM> of antenna base 12D is screwed with screw groove <NUM> of shaft section <NUM>.

In guide sections <NUM>, slide grooves <NUM> are formed in a longitudinal direction. Guide sections <NUM> are fixed to side wall section <NUM> such that slide grooves <NUM> are in parallel with shaft section <NUM>. Projecting section <NUM> of antenna base 12D is inserted to slide grooves <NUM>. Thus, rotation of antenna base 12D is prevented. Accordingly, slide grooves <NUM> and projecting section <NUM> of antenna base 12D correspond to one example of rotation preventing mechanisms.

By employing the configuration of antenna apparatus 10D, since screw groove <NUM> of shaft section <NUM> and screw hole <NUM> of antenna base 12D are screwed with each other, by rotating handle section <NUM> and axially rotating shaft section <NUM>, a height of antenna base 12D can be changed.

For example, by rotating handle section <NUM> clockwise, a position of antenna base 12D can be moved upward (in a direction approaching manhole cover <NUM>). Conversely, by rotating handle section <NUM> counterclockwise, the position of antenna base 12D can be moved downward (in a direction away from manhole cover <NUM>). At this time, since projecting section <NUM> inserted into slide grooves <NUM> is capable of preventing the rotation of antenna base 12D, antenna base 12D moves in upward and downward directions without rotating.

In addition, guide sections <NUM> may be provided with scale <NUM> in a height direction. Thus, even without separately using a surveying tool, the height of antenna base 12D can be visually checked. In other words, on an installation site thereof, adjustment of an electromagnetic field strength of radio waves can be further facilitated.

As described above, in Embodiment <NUM>, the configuration of antenna apparatus 10D of an underground embedded type is adopted in which screw hole <NUM> of antenna base 12D and screw groove <NUM> of shaft section <NUM> are screwed with each other and handle section <NUM> is welded to the one end of shaft section <NUM>. Thus, on the installation site of antenna apparatus 10D, a worker rotates handle section <NUM> and can thereby easily adjust the height of antenna base 12D.

Next, with reference to <FIG>, a configuration of antenna apparatus 10E according to Embodiment <NUM> will be described. <FIG> is a perspective view of antenna apparatus 10E. Note that components of antenna apparatus 10E which are in common with those in antenna apparatus 10D shown in <FIG> are denoted by the same reference signs, and the description for the components in common therewith will be omitted.

As with antenna apparatus 10D, antenna apparatus 10E includes antenna elements <NUM>, antenna angle adjustment mechanisms <NUM>, and shaft section <NUM>. In addition, antenna apparatus 10E includes antenna base 12E, supporting columns <NUM>, handle section <NUM>, and manhole cover <NUM>. Antenna base 12E is different from antenna base 12B shown in <FIG> in that through holes <NUM> are formed in portions other than a central portion thereof. An inner diameter of each of through holes <NUM> is larger than an outer diameter of each of supporting columns <NUM>.

Supporting columns <NUM> and shaft section <NUM> in antenna apparatus 10E correspond to one example of supporting section <NUM> of antenna apparatus <NUM>. Screw hole <NUM> of antenna base 12E and screw groove <NUM> of shaft section <NUM> in antenna apparatus 10E correspond to one example of antenna height adjustment mechanisms <NUM>.

Supporting columns <NUM> are fixed vertically with respect to manhole cover <NUM> in the portions other than the central portion of manhole cover <NUM> and extend downward. <FIG> shows an example in which the number of supporting columns <NUM> is two. Note, however, that the present embodiment is not limited thereto and the number of supporting columns <NUM> may be one and may be three or more.

Shaft section <NUM> is provided vertically with respect to manhole cover <NUM> in the central portion of manhole cover <NUM> and extends downward. An upper end of shaft section <NUM> is received by a bearing section (not shown) of manhole cover <NUM> and shaft section <NUM> is axially rotatable.

Screw hole <NUM> of antenna base 12E is screwed with screw groove <NUM> of shaft section <NUM>. In addition, each of supporting columns <NUM> is inserted into each of through holes <NUM> of antenna base 12E.

Handle section <NUM> can be coupled to shaft section <NUM>. Handle section <NUM> is coupled to shaft section <NUM> and handle section <NUM> is rotated, whereby shaft section <NUM> is axially rotated.

In the central portion of manhole cover <NUM>, through hole <NUM> for coupling handle section <NUM> to shaft section <NUM> from an outside is formed.

By employing the configuration of antenna apparatus 10E, since screw groove <NUM> of shaft section <NUM> and screw hole <NUM> of antenna base 12E are screwed with each other, by coupling handle section <NUM> to shaft section <NUM> via through hole <NUM> of manhole cover <NUM> and rotating handle section <NUM>, a height of antenna base 12E can be changed. In other words, even without opening manhole cover <NUM>, the height of antenna base 12E can be adjusted.

For example, by rotating handle section <NUM> clockwise and rotating shaft section <NUM>, a position of antenna base 12E can be moved upward (in a direction approaching manhole cover <NUM>). Conversely, by rotating handle section <NUM> counterclockwise and rotating shaft section <NUM>, the position of antenna base 12E can be moved downward (in a direction away from manhole cover <NUM>).

At this time, since supporting columns <NUM> inserted into through holes <NUM> of antenna base 12E are capable of preventing rotation of antenna base 12E, antenna base 12E moves in upward and downward directions without rotating. Accordingly, through holes <NUM> of antenna base <NUM> and supporting columns <NUM> inserted into through holes <NUM> correspond to one example of rotation preventing mechanisms.

Note that shaft section <NUM> or supporting columns <NUM> may be provided with a scale (not shown) in a height direction. Thus, even without separately using a surveying tool, the height of antenna base 12E can be visually checked. In other words, adjustment of an electromagnetic field strength of radio waves on an installation site thereof can be further facilitated.

As described above, in Embodiment <NUM>, the configuration of antenna apparatus 10E of an underground embedded type is adopted in which screw hole <NUM> of antenna base 12E and screw groove <NUM> of shaft section <NUM> are screwed with each other and handle section <NUM> can be coupled to shaft section <NUM> via through hole <NUM> of manhole cover <NUM>. On the installation site of antenna apparatus 10E, by coupling handle section <NUM> to shaft section <NUM> via through hole <NUM> of manhole cover <NUM> and rotating handle section <NUM>, a worker can easily adjust the height of antenna base 12E without opening manhole cover <NUM>.

Next, with reference to <FIG>, a configuration of antenna apparatus 10F according to Embodiment <NUM> will be described. <FIG> is a perspective view of antenna apparatus 10F. <FIG> is a plan view of antenna apparatus 10F. <FIG> is a side view of antenna apparatus 10F. Note that <FIG> is a diagram in which a height of antenna apparatus 10F is increased and antenna apparatus 10F is housed in manhole <NUM>.

Antenna apparatus 10F includes bottom frame <NUM>, leg sections <NUM>, supporting columns <NUM>, upper frame <NUM>, first reinforcing member <NUM>, second reinforcing member <NUM>, antenna elements <NUM>, apparatus attaching plates <NUM>, and handles <NUM>.

Bottom frame <NUM> has a rectangular frame structure. In four corners of bottom frame <NUM>, holes <NUM> for fixing leg sections <NUM> are formed.

Each of four leg sections <NUM> has grounding section <NUM>, rod <NUM> vertically extending upward from grounding section <NUM>, and height adjuster <NUM> which is screwed with a screw groove formed on rod <NUM> and is movable through rotation in upward and downward directions.

Each rod <NUM> in each leg section <NUM> is inserted into each of holes <NUM> in the corners of bottom frame <NUM> from above. As shown in <FIG>, with a bottom surface of bottom frame <NUM> contacting upper surfaces of height adjusters <NUM>, the bottom frame <NUM> is supported by the height adjusters <NUM>. By moving positions of height adjusters <NUM> in upward and downward directions, a height position of bottom frame <NUM>, that is, a height h from upper ends of antenna elements <NUM> of antenna apparatus 10F up to an upper surface (ground surface) of manhole cover <NUM> is adjusted. As described above, the height h is adjusted, thereby allowing an electromagnetic field strength of radio waves to be adjusted so as to satisfy the conditions in the radio wave protection guidelines. Nuts (not shown) are screwed from above rods <NUM>, thereby fixing leg sections <NUM> to bottom frame <NUM>.

For grounding sections <NUM> of leg sections <NUM>, a rubber material may be used. The rubber material is used for grounding sections <NUM>, thereby allowing transmission of vibration of manhole <NUM> to antenna apparatus 10F to be inhibited and enabling displacement of a position of antenna apparatus 10F inside the manhole <NUM> to be inhibited.

Lower ends of four supporting columns <NUM> are fixed to the four corners of bottom frame <NUM>, respectively and four supporting columns <NUM> vertically extend upward. As shown in <FIG> and <FIG>, outside surfaces of supporting columns <NUM> are chamfered in order not to damage an inner wall of manhole <NUM> when antenna apparatus 10F is housed therein and taken thereout.

Upper frame <NUM> has a rectangular frame structure which is similar to that of bottom frame <NUM>. Four corners of upper frame <NUM> are fixed to upper ends of four supporting columns <NUM>.

First reinforcing member <NUM> is provided on one diagonal line of bottom frame <NUM>, and both ends thereof are fixed to corners or sides of bottom frame <NUM>, respectively. Thus, a frame structure of bottom frame <NUM> is reinforced.

Second reinforcing member <NUM> is provided on one diagonal line of upper frame <NUM>, which is in parallel with first reinforcing member <NUM>, and both ends thereof are fixed to corners or sides of upper frame <NUM>. Thus, the frame structure of upper frame <NUM> is reinforced.

Two antenna elements <NUM> are installed on second reinforcing member <NUM> and vertically extend upward. Two antenna elements <NUM> can be installed on any positions on second reinforcing member <NUM>. For example, as shown in <FIG>, an interval between two antenna elements can be adjusted.

In addition, a length of second reinforcing member <NUM> is longer than a length of one side of upper frame <NUM>. Thus, as in the present embodiment, two antenna elements <NUM> are provided on second reinforcing member <NUM>, thereby allowing a range of movement of two antenna elements <NUM> to be made larger than that made when two antenna elements <NUM> are provided on one side of upper frame <NUM>. In other words, the interval between two antenna elements <NUM> can be more flexibly adjusted.

As described above, on the diagonal line of upper frame <NUM>, second reinforcing member <NUM> is provided, and on second reinforcing member <NUM>, antenna elements <NUM> are installed, thereby allowing both of the reinforcement of upper frame <NUM> and the expansion of the range of movement of antenna elements <NUM> to be realized.

One end of each of apparatus attaching plates <NUM> is fixed to first reinforcing member <NUM> and the other end each thereof is fixed to second reinforcing member <NUM>. As shown in <FIG>, on apparatus attaching plates <NUM>, radio equipment (SRE: low power Small optical remote Radio Equipment) <NUM> is attached. Note that each of apparatus attaching plates <NUM> may be provided with a mechanism for fixing radio equipment <NUM>. The mechanism may be a slide mechanism. Alternatively, the mechanism may be a fastening mechanism constituted of bolts and nuts. In addition, as shown in <FIG>, positions of apparatus attaching plates <NUM> in upward and downward directions may be optionally changeable in accordance with a size of radio equipment <NUM>.

Antenna elements <NUM> are connected to radio equipment <NUM> via connector cables (not shown). Note that an assembly in which antenna apparatus 10F is equipped with radio equipment <NUM> may be called a radio base station.

Two handles <NUM> are fixed on sides of upper frame <NUM> which face each other, respectively. Handles <NUM> are used upon taking antenna apparatus 10F out of manhole <NUM>.

Supporting columns <NUM> are provided with hooks <NUM>, respectively. Communication cable <NUM> and electric cable <NUM> connecting to radio equipment <NUM> through pipe conduit <NUM> (refer to <FIG>) have lengths including allowance in order to allow antenna apparatus 10F to be taken out of manhole <NUM>. Therefore, as shown in <FIG>, upon housing antenna apparatus 10F in manhole <NUM>, cables <NUM> and <NUM> are hooked on hooks <NUM>. Thus, disconnection of cables <NUM> and <NUM>, caused by entwining, folding, or the like thereof, can be prevented. As shown in <FIG>, hooks <NUM> project in directions from supporting columns <NUM> toward an inside of antenna apparatus 10F. Through this configuration, upon housing antenna apparatus 10F in manhole <NUM>, hooks <NUM> are not caught to manhole <NUM>. Note, however, that this configuration is one example, hooks <NUM> may project in directions from supporting columns <NUM> toward an outside of antenna apparatus 10F, and a configuration other than this configuration may be adopted.

As shown in <FIG>, a maximum width (a length on the diagonal line) F1 of antenna apparatus 10F may be a length as close to an inner diameter R1 of manhole <NUM> as possible in a range allowing antenna apparatus 10F to be housed in manhole <NUM>.

Note that first reinforcing member <NUM> and second reinforcing member <NUM> are not directly fixed to bottom frame <NUM>, and upper frame <NUM>, respectively, and the components (hereinafter, referred to as "apparatus attachment parts") configured by first reinforcing member <NUM>, second reinforcing member <NUM>, antenna elements <NUM>, and apparatus attaching plates <NUM> may be configured as described below. In other words, the apparatus attachment parts may have slide mechanisms (not shown) in upward and downward directions. Through this configuration, without taking the whole of antenna apparatus 10F out of manhole <NUM>, the apparatus attachment parts can be taken out of manhole <NUM>. Thus, maintenance work for antenna elements <NUM> and radio equipment <NUM> is facilitated. Note that in this case, in order to make a sliding operation of the apparatus attachment parts easy, handles (not shown) may be provided on second reinforcing member <NUM>.

<FIG> shows an example of a sectional view of a side surface of manhole <NUM>. <FIG> shows an example of a plan view of manhole <NUM>. <FIG> shows an example of a sectional view, taken from line A-A' in the diagram of manhole <NUM> shown in <FIG>.

A height H1 of an inside of manhole <NUM> is longer than a height of the whole of antenna apparatus 10F including antenna elements <NUM>. Thus, antenna apparatus 10F can be housed in manhole <NUM>. A height H2 may be, for example, <NUM>.

A thickness H2 of manhole cover <NUM> is a thickness having a strength causing no problem even when a person, an automobile, or the like gets on manhole cover <NUM>. Note, however, that it is preferable that manhole cover <NUM> is manufactured by using a material which does not exert any influence on propagation of the radio waves of antenna apparatus 10F installed inside manhole <NUM>. For example, manhole cover <NUM> may be formed of FRP (Fiber-Reinforced Plastics). In this case, the thickness H2 of manhole cover <NUM> may be, for example, <NUM>.

A height H3 of the whole of manhole <NUM> is a size in consideration of the height H1 of the inside of the manhole and the height H2 of manhole cover <NUM> as mentioned above. For example, the height H3 may be <NUM>.

An inner diameter R1 of a gateway of manhole <NUM> is, as shown in <FIG>, larger than a maximum width F1 (the length of antenna apparatus 10F on the diagonal line) of antenna apparatus 10F. Thus, antenna apparatus 10F can be housed in manhole <NUM> and can be taken out of manhole <NUM>. The inner diameter R1 may be, for example, <NUM>.

A shape of the inside of manhole <NUM> may be a cylindrical shape or may be a rectangular parallelepiped shape. In addition, manhole <NUM> may be formed of the FRP (Fiber-Reinforced Plastics) or may be formed of resin (plastic).

In addition, as shown in <FIG>, manhole <NUM> may be provided with a drain hole <NUM> formed in a bottom surface thereof. Thus, rain water entering manhole <NUM> can be permeated (drained) through drain hole <NUM> into the ground.

In addition, as shown in <FIG>, manhole <NUM> may be provided with through hole <NUM> formed in a side surface thereof. Through hole <NUM> is formed at a height at which through hole <NUM> communicates with pipe conduit <NUM> shown in <FIG> when manhole <NUM> is embedded in the ground. Through this configuration, through pipe conduit <NUM> and through hole <NUM>, communication cable <NUM> and electric cable <NUM> can be drawn inside manhole <NUM>.

As described above, in manhole <NUM>, antenna apparatus 10F is housed. Accordingly, manhole <NUM> may be called an antenna apparatus housing body.

<FIG> is a diagram showing a configuration example of a demonstration experiment station for an antenna apparatus of an underground embedded type.

First, an evaluation method will be described. The demonstration experiment station was installed in a management environment which allowed sufficient isolation from locations, where the general public was able to walk, to be ensured. A configuration of the demonstration experiment station is as shown in <FIG>. As specifications of the demonstration experiment station, an FDD-LTE system and a frequency band of <NUM> (BAND21) were employed.

Under the conditions, with the center of a surface of a manhole cover as the origin, power densities at specified calculation points in the periphery immediately above the cover were measured.

In order to set each interval among the calculation points in a horizontal direction to specified λ/<NUM> (in this case, <NUM>) or less and to conduct conservative evaluation, while a measuring instrument set in a MaxHold state was swept, the calculation points at respective heights were scanned in the horizontal direction with a sensor section of the measuring instrument, thereby obtaining a maximum value among measured values of the power densities at the respective heights in the horizontal direction. As a result, it was found out that by increasing a height from antenna elements <NUM> up to a surface (ground surface) of manhole cover <NUM>, the power density was decreased. In other words, it was found out that by adjusting heights of leg sections <NUM>, it was made possible to adjust an electromagnetic field strength of radio waves so as to satisfy the conditions in the radio wave protection guidelines.

When an outdoor temperature is high, a temperature inside manhole <NUM> is likely to be high. Therefore, for radio equipment <NUM> of antenna apparatus 10F housed in manhole <NUM>, a cooling section for inhibiting radio equipment <NUM> from being highly heated may be provided. For example, radio equipment <NUM> may be covered by a cooling section (housing) having water or a coolant thereinside. Alternatively, a cooling section (sheet) for blocking heat from an outside may be attached onto manhole cover <NUM>.

Rain water is likely to enter an inside of manhole <NUM>. Therefore, radio equipment <NUM> of antenna apparatus 10F housed in manhole <NUM> may be subjected to waterproofing treatment.

In antenna apparatus 10F housed in manhole <NUM>, two or more pieces of radio equipment <NUM> may be attached. For example, in antenna apparatus 10F housed in manhole <NUM>, radio equipment for LTE and/or <NUM> and radio equipment (for example, a LoRa master unit) for LPWA (Low Power, Wide Area) may be attached. Thus, since as compared with a case in which a manhole is provided for each radio equipment, the number of manholes can be reduced, an installation cost and a maintenance cost required for the radio equipment can be suppressed.

Antenna apparatus 10F according to Embodiment <NUM> is antenna apparatus 10F of an underground embedded type disposed below manhole cover <NUM>, which includes antenna elements <NUM> and installation bases (<NUM> and <NUM>) on which antenna elements <NUM> are installed and which has height adjustment mechanisms (<NUM> and <NUM>) for adjusting a distance from antenna elements <NUM> to manhole cover <NUM>. Thus, adjustment which satisfies the radio wave protection guidelines and adjustment of a communication area can be made possible. Note that on the installation bases, the two antenna elements may be installed so as to allow a distance between the two antenna elements to be adjusted. In addition, the antenna elements may extend in a direction approaching the manhole cover from the installation bases.

The radio base station according to Embodiment <NUM> includes the above-described antenna apparatus 10F and radio equipment <NUM> which is attached on the installation bases of antenna apparatus 10F, is connected to antenna elements <NUM> by the cables, and performs radio processing for signals transmitted from antenna apparatus 10F and signals received by antenna apparatus 10F. Thus, lengths of the cables connecting radio equipment <NUM> and antenna elements <NUM> can be made short, thereby allowing signal attenuation in the cables to be suppressed. Thus, in addition, since radio equipment <NUM> and antenna apparatus 10F can be housed in manhole <NUM> in an integrated manner (that is, as the radio base station), installation and maintenance of the radio base station are facilitated. In addition, the installation bases may have hooks <NUM> for retaining the cables (<NUM> and <NUM>) connected from a backhaul to radio equipment <NUM>. Thus, the cables for the backhaul, which have lengths having the allowance so as to allow the maintenance to be conducted by taking the radio base station out of the manhole, are hooked on hooks <NUM> upon housing the radio base station in manhole <NUM> and can be bundled.

The antenna apparatus housing body according to Embodiment <NUM> includes the container (<NUM>) whose upper surface being the closest surface to the ground surface when installed in the ground opens and which is capable of housing the above-described antenna apparatus 10F and the cover (<NUM>) which is formed of the FRP (Fiber-Reinforced Plastics) and covers an opening of the container. Thus, without exerting any influence on the propagation of the radio waves of antenna apparatus 10F housed, a high load resistant strength can be obtained. In addition, the container may be provided with the drain hole (<NUM>) formed in the lower surface and the through hole (<NUM>) formed in the side surface. Thus, the rain water entering manhole <NUM> can be drained. In addition, the cables (<NUM> and <NUM>) for the backhaul can be drawn inside the container and be connected to radio equipment <NUM>.

The above-described Embodiments are illustrative for the description of the present invention, and it is not intended that the scope of the present invention is limited merely to the Embodiments. Those skilled in the art can implement the present invention in other various modes without departing from the gist of the present invention.

For example, although in each of the above-described Embodiments, the example in which the number of antenna elements <NUM> is two is illustrated, the number of antenna elements <NUM> may be one or may be three or more.

Claim 1:
An antenna apparatus (<NUM>) of an underground embedded type comprising:
an antenna element (<NUM>);
an installation base (<NUM>) being a base where the antenna element (<NUM>) is installed;
a container (<NUM>) including an upper surface having an opening and configured to house the antenna element (<NUM>) and the installation base (<NUM>), the upper surface being a surface closest to a ground surface when the container (<NUM>) is installed in a ground; and
a cover (<NUM>) being formed of FRP, Fiber-Reinforced Plastics, and configured to cover the opening of the container (<NUM>),
wherein the installation base (<NUM>) includes a height adjustment mechanism configured to adjust a distance from the antenna element (<NUM>) to the cover (<NUM>) by adjusting a height of the installation base (<NUM>).