JP4925891B2 - antenna - Google Patents

Description

  The present invention relates to an antenna, and more particularly to an antenna capable of changing a main beam direction.

  Conventionally known antennas can change the direction of the main beam. For example, Japanese Patent Laying-Open No. 2006-165672 (Patent Document 1) discloses a double loop antenna including a plurality of loop antenna elements, a coupling line that couples the plurality of antenna elements, and a power feeding unit that feeds power to the coupling line. Disclose. In this antenna, by adjusting the interval between the plurality of antenna elements, the feeding phase of the antenna element located on one side with respect to the feeding part becomes a leading phase, and the antenna located on the other side with respect to the feeding part The power feeding phase of the element is a delayed phase. In this way, it is possible to change the direction of the main beam by feeding power to a plurality of antenna elements.

On the other hand, since the installation location of the antenna is limited when the antenna is enlarged, the antenna is preferably small. For example, Japanese Patent Laying-Open No. 2002-84131 (Patent Document 2) discloses a UHF (Ultra High Frequency) antenna that can be miniaturized. The UHF antenna includes a radiating conductor having a substantially semi-cylindrical shape and a reflecting conductor arranged so as to cover the radiating conductor from the rear. The shape of the reflective conductor is almost a semi-cylinder. The central axis of the reflective conductor is the same as the central axis of the radiation conductor.
JP 2006-165672 A JP 2002-84131 A

  In the case of the antenna disclosed in Japanese Patent Laying-Open No. 2006-165672 (Patent Document 1), a plurality of antenna elements are required. Further, it is necessary to connect a delay line for making the feeding phase a delayed phase to the coupled line. Therefore, in the case of the antenna described above, there is a high possibility that the size will increase.

  On the other hand, in the case of the UHF antenna disclosed in Japanese Patent Laid-Open No. 2002-84131 (Patent Document 2), the direction of the main beam cannot be changed. Therefore, since this UHF antenna must be installed in a place where radio wave reception is good, the installation place is limited.

  An object of the present invention is to provide an antenna that can change the direction of a main beam and can be miniaturized.

In summary, the present invention is an antenna, to which a radiator, a reflector, a radiator and a reflector are attached, and at least one of the radiator and the reflector can be mounted along a predetermined direction. A position adjusting unit. The position adjusting unit is a cylindrical body having insulating properties. The predetermined direction is a direction along the central axis of the cylindrical body. The radiator is attached to the inner wall while being bent along the inner wall of the cylindrical body. The reflector is attached to the outer wall while being bent along the outer wall of the cylinder .

According to another aspect of the present invention, the antenna includes a radiator, a reflector, the radiator and the reflector, and an attachment position of at least one of the radiator and the reflector is adjusted along a predetermined direction. Possible position adjustment unit. The position adjusting unit includes a first insulating substrate having a first main surface and a second main surface that is movable in a direction along the first main surface and parallel to the first main surface. And a second insulating substrate. The radiator is formed on the first major surface. The reflector is formed on the second main surface.
Preferably, the predetermined direction is the vertical direction of the antenna when the antenna is installed.
More preferably, the position adjusting unit can adjust the attachment position of the reflector while fixing the attachment position of the radiator.

More preferably, the radiator includes a loop element .

  According to the present invention, it is possible to realize an antenna that can change the direction of the main beam and can be miniaturized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

<Overall configuration>
FIG. 1 is a diagram illustrating an installation example of an antenna 100 according to an embodiment of the present invention. Referring to FIG. 1, antenna 100 is installed on the top (top side) of utility pole 300 in a state of being stored in storage container 200. The diameter of the storage container 200 is substantially the same as the diameter of the utility pole 300. For this reason, even if the storage container 200 is attached to the utility pole 300, the storage container 200 is less noticeable. Therefore, it is possible to prevent the beauty of the utility pole 300 from being impaired.

  Although not shown in detail in FIG. 1, a reception antenna (not shown) for receiving a radio wave (for example, a terrestrial digital broadcast wave) transmitted from a television broadcasting station or the like is provided on the center side. In a CATV facility that transmits a television broadcast signal to a terminal via a re-transmission device 120, a re-transmission device 120 is provided on the transmission line 140. The retransmitting device 120 supplies a television broadcast signal whose power is equal to or less than a desired value to the antenna 100 via the transmission line 140. The antenna 100 retransmits this television broadcast signal to a region obliquely below.

  Here, since there are large buildings or mountains (both not shown) around the general household 400, the antenna 410 cannot directly receive radio waves transmitted from a television broadcasting station or the like. However, when the antenna 410 receives the radio wave from the antenna 100, the user can view the television program. Radio waves received by the antenna 410 are sent to the television receiver 420. The television receiver 420 reproduces video and audio by performing predetermined processing on the radio wave received by the antenna 410.

  The direction in which the antenna 100 transmits radio waves is adjusted by a worker after the antenna 100 is installed on the top of the utility pole 300. The antenna 100 transmits radio waves below the antenna 100. As a result, the user can view the TV program in an area (including the general household 400) where the radio wave transmitted from the TV broadcasting station or the like cannot be directly received.

  In the present embodiment, antenna 100 is a UHF antenna, particularly an antenna for terrestrial digital broadcasting. However, the use frequency band of the antenna 100 is not limited to the UHF band, and may be a higher frequency band (for example, a GHz band) or a lower frequency band (for example, a VHF (Very High Frequency) band).

  FIG. 2 is a diagram illustrating the configuration of the antenna 100 of FIG. Referring to FIG. 2, antenna 100 includes radiator 1, reflector 2, and position adjustment unit 3.

  Radiator 1 includes a loop element 11 and a parasitic element 12 provided for adjusting the impedance of radiator 1. However, only the loop element 11 may be used as the radiator 1. By using a loop element as the power feeding element, the gain of the radiator 1 can be increased.

  The position adjustment unit 3 has an insulating property and is formed in a cylindrical shape. The radiator 1 (the loop element 11 and the parasitic element 12) is attached to the inner wall 21 of the position adjusting unit 3 (cylindrical body) along the inner wall 21. The reflector 2 is attached to the outer wall 22 of the position adjusting unit 3 along the outer wall 22. The radiator 1 may be fixed to the inner wall 21 of the position adjusting unit 3 with, for example, an insulating tape, or may be fixed to the inner wall 21 of the position adjusting unit 3 with a filler filled in the position adjusting unit 3. Also good.

  The reflector 2 is provided with two holes through which the bolts 5 pass. Two slide grooves 4 along the Z direction are formed at two positions of the position adjusting unit 3. The reflector 2 is attached to the position adjustment unit 3 so that the hole overlaps the slide groove 4.

  The bolt 5 is passed through the hole of the reflector 2 and the slide groove 4, and is coupled to the nut 6 inside the position adjusting unit 3. Accordingly, the reflector 2 can be slid in the Z direction, and the reflector 2 can be fixed at an arbitrary position in the Z direction.

  The Z direction is a direction along the central axis 15 of the cylinder. In particular, when the antenna 100 is installed as shown in FIG. 1, the direction of the central axis 15 is along the vertical direction of the antenna 100, and the Z direction is below the antenna 100. In FIG. 2, the X direction is a direction that passes through the center of the radiator 1 and is perpendicular to the Z direction. The Y direction is a direction perpendicular to the X direction and the Z direction.

  By sliding the reflector 2 in the Z direction, the direction of the main beam of the antenna 100 can be changed. In particular, when the center position of the reflector 2 is shifted downward from the center position of the radiator 1, when the radio wave transmitted from the radiator 1 is reflected by the reflector 2, the radio wave travels obliquely downward of the antenna 100. That is, as shown in FIG. 1, radio waves can be transmitted obliquely below the antenna 100.

  Furthermore, according to the present embodiment, the direction of the main beam of the antenna 100 can be changed by simply sliding the reflector 2 in the Z direction. That is, according to the present embodiment, it is possible to change the direction of the main beam while simplifying the configuration of the antenna as compared with the case where phase difference feeding is performed on a plurality of feeding elements.

  Furthermore, according to the present embodiment, the radiator 1 and the reflector 2 are respectively attached to the inner wall and the outer wall of one cylindrical body (position adjusting unit 3), so that the antenna can be reduced in size.

  FIG. 3 is a development view of radiator 1 shown in FIG. In FIG. 3, radiator 1 (loop element 11 and parasitic element 12) is developed on a virtual plane A. The Y direction and Z direction shown in FIG. 3 are the same as the Y direction and Z direction shown in FIG. The plane A corresponds to the antenna main surface of the loop element 11.

  Next, the dimensions of radiator 1 will be described. In addition, the dimension shown below is an example, Comprising: The dimension of the radiator 1 can be set appropriately according to the performance etc. which are calculated | required by the radiator 1. FIG.

  The loop element 11 is a square, and the length of one side thereof is about 144 mm. The width of the loop element 11 is about 12 mm. The loop element 11 has feeding points FD1 and FD2. A gap of about 10 mm is formed between the feeding point FD1 and the feeding point FD2.

  The length of the parasitic element 12 in the Y direction is about 180 mm, and the length of the parasitic element 12 in the Z direction is about 189 mm. The width of the parasitic element 12 is about 15 mm. The interval (Y direction) between the parasitic element 12 and the loop element 11 is about 3 mm. The distance between the parasitic element 12 and the loop element 11 on the side of the feeding points FD1 and FD2 is about 9 mm. The distance between the parasitic element 12 and the loop element 11 on the side farthest from the feeding point FD1 (FD2) is about 6 mm.

<Characteristics of radiator>
FIG. 4 is a view of only the radiator 1 among the components of the antenna 100 shown in FIG. 2 as viewed along the X direction, the Y direction, and the Z direction. Referring to FIGS. 4 and 2, the dimension in the Z direction of radiator 1 when viewed along the X direction is about 189 mm. As shown in FIG. 2, the radiator 1 (the loop element 11 and the parasitic element 12) is bent along the inner wall of the cylindrical body and attached to the inner wall. Therefore, when viewed along the Z direction, the shape of the radiator 1 is a part of the circumference (substantially a semicircle). The diameter of this circle is about 115 mm.

  Next, gain, VSWR (Voltage Standing Wave Ratio), front-to-back ratio, half width, and directivity will be described as the characteristics of the radiator. In addition, when explaining directivity, the radiation direction of the radiator 1 is important. Therefore, first, the horizontal plane and the vertical plane of the radiator 1 will be described so that the radiation direction of the radiator 1 can be easily understood.

  FIG. 5 is a diagram for explaining the positional relationship between the antenna main surface, the horizontal plane, and the vertical plane of the loop element 11. In FIG. 5, the X direction, Y direction, and Z direction are the same as the X direction, Y direction, and Z direction in FIG.

  The radio wave S is a horizontally polarized wave whose electric field direction is horizontal. In many cases, TV radio waves are horizontally polarized.

  The YZ plane corresponds to the antenna main surface of the loop element 11. The XY plane is a plane parallel to the electric field of the radio wave S and is orthogonal to the YZ plane. The ZX plane is perpendicular to both the YZ plane and the XY plane. Hereinafter, the XY plane is referred to as a “horizontal plane”, and the ZX plane is referred to as a “vertical plane”.

  FIG. 6 is a diagram illustrating the gain of the radiator 1. In FIG. 6, the frequency range is 470 to 710 MHz. This range is included in the frequency band of terrestrial digital broadcasting in Japan. In the range of 470 to 710 MHz, the gain of radiator 1 is approximately 0 (dB) or more. The higher the gain, the better the performance of the radiator.

  Here, also in the figures described below, the frequency range is a range of 470 to 710 MHz. Therefore, the description regarding the frequency range will not be repeated hereinafter.

  FIG. 7 is a diagram illustrating the VSWR of the radiator 1. The lower the VSWR, the better the performance of the radiator. Referring to FIG. 7, VSWR is approximately 2 or less in the frequency range of 470 to 710 MHz.

  FIG. 8 is a diagram illustrating the front-to-back ratio and the half-value width of the radiator 1. The front-to-back ratio is the ratio of the radiant intensity in the direction of the reference point (angle 0 degree) and the radiant intensity in the direction of 180 ° ± 60 degrees with respect to the direction of the reference point. The half-value width is an angle width at which the radiation intensity (radiation power) is ½ of the maximum value.

  As shown in FIG. 8, the front-to-back ratio (shown by the solid line) is substantially 0 (dB) in the frequency range of 470 to 710 MHz. The full width at half maximum (indicated by a broken line) is a value in a range from approximately 45 degrees to 60 degrees in the frequency range of 470 to 710 MHz.

  FIG. 9 is a diagram illustrating the directivity of the radiator 1 on a horizontal plane. Referring to FIG. 9, the direction of 0 degrees is the direction in which the radiation intensity of radiator 1 is maximized, and corresponds to “the direction of the main beam” in the present embodiment.

  When radiator 1 is formed on a plane as shown in FIG. 3, the directivity of radiator 1 is strong in the directions of 0 degrees and 180 degrees, and weak in the directions of 90 degrees and 270 degrees. For this reason, the figure showing directivity is a so-called “eight-shape”. However, in the present embodiment, the radiator 1 is bent around the axis of the central axis 15 of the position adjusting unit 3, so that the radiator 1 has directivity also in the 90-degree direction and the 270-degree direction on the horizontal plane. The radiator 1 has substantially the same directivity at each frequency of 470 MHz, 590 MHz, and 710 MHz.

  FIG. 10 is a diagram showing the directivity of radiator 1 on a vertical plane. In FIG. 10, directions of 0 degrees and 180 degrees correspond to directions of 0 degrees and 180 degrees on the horizontal plane, respectively. The directions of 90 degrees and 270 degrees correspond to the upper and lower portions of the radiator 1 shown in FIG. In the present embodiment, in particular, directivity in the range of a quarter circle from 270 degrees to 0 degrees is important. The directivity in this range is substantially the same at each frequency of 470 MHz, 590 MHz, and 710 MHz.

<Antenna characteristics (no tilt)>
FIG. 11 is a view of radiator 1 and reflector 2 shown in FIG. 2 as viewed along the X direction, the Y direction, and the Z direction. FIG. 11 shows a state where the reflector 2 is not moved in the Z direction. In this state, when viewed from the X direction, the center of the reflector 2 coincides with the center of the radiator. This state is hereinafter referred to as “no tilt”. A state in which the center of the reflector 2 is shifted in the Z direction with respect to the center of the radiator 1 when viewed from the X direction will be referred to as “with tilt” hereinafter.

  Referring to FIG. 11, the size of radiator 1 in the Z direction is about 189 mm, while the size of reflector 2 in the Z direction is about 200 mm. Moreover, the reflector 2 is arrange | positioned so that the radiator 1 may be covered from back. As shown in FIG. 2, the reflector 2 is bent along the outer wall of the cylindrical body and attached to the outer wall. Therefore, when viewed along the Z direction, the shape of the reflector 2 is a part of the circumference. The diameter of this circle is about 170 mm.

  FIG. 12 is a diagram showing the gain in the front direction of the antenna 100 (no tilt). The front direction corresponds to the X direction in FIG. With reference to FIG. 12 and FIG. 6, it can be seen that by providing the reflector 2 behind the radiator 1, the gain is increased by about 1 to 2 (dB) in the frequency range of 470 to 710 MHz.

  FIG. 13 is a diagram showing the VSWR in the front direction of the antenna 100 (no tilt). Referring to FIG. 13 and FIG. 7, there is almost no change in VSWR due to the presence or absence of reflector 2 in the frequency range of 530 to 710 MHz. Compared with FIG. 7, VSWR is slightly higher in the frequency range of 470 to 530 MHz in FIG. 13, but the value of VSWR in this range is a level that is not particularly problematic in practical use.

  FIG. 14 is a diagram illustrating the front-rear ratio and the half-value width in the front direction of the antenna 100 (no tilt). Referring to FIGS. 14 and 8, it can be seen that both the front-rear ratio and the half-value width are increased by providing the reflector 2 behind the radiator 1. FIG. 14 shows that the directivity of the antenna 100 in the front direction is enhanced by the reflector 2.

  FIG. 15 is a diagram illustrating the directivity of the antenna 100 (no tilt) on a horizontal plane. FIG. 16 is a diagram showing the directivity of the antenna 100 (no tilt) on the vertical plane. Referring to FIGS. 15 and 16, it can be seen that the directivity in the front direction (0 degree direction) of antenna 100 is stronger than the directivity in the rear direction (180 degrees) of antenna 100. 15 and 16 also show that the directivity in the front direction of the antenna 100 is enhanced by providing the reflector 2 behind the radiator 1.

<Antenna characteristics (with tilt)>
FIG. 17 is a diagram of the antenna 100 (with tilt) viewed along the X direction, the Y direction, and the Z direction. As can be seen from the X direction, the center OB of the reflector 2 is shifted downward (Z direction) by about 80 mm with respect to the center OA of the radiator 1.

  FIG. 18 is a diagram showing the gain in front of and obliquely below the antenna 100 (with tilt). 18 and 12, it can be seen that the gain in the frequency range of 470 to 710 MHz is increased by moving the reflector 2 below the radiator 1. That is, FIG. 18 shows that by moving the reflector 2 below the radiator 1, the direction of the main beam is tilted obliquely below the radiator 1 (that is, obliquely below the antenna 100).

  FIG. 19 is a diagram illustrating the directivity of the antenna 100 (with tilt) on a horizontal plane. Referring to FIGS. 19 and 15, it can be seen that there is almost no change in the directivity on the horizontal plane even when the reflector 2 is moved below the radiator 1.

  FIG. 20 is a diagram showing the directivity of the antenna 100 (with tilt) on the vertical plane. Referring to FIGS. 20 and 16, the direction in which the radiation intensity of antenna 100 is maximized by moving reflector 2 below radiator 1 is the direction from about 0 degrees to about 30 degrees below antenna 100 (about about 100 degrees). It can be seen that the angle changes in the direction of 330 degrees. This result indicates that the direction of the main beam is inclined about 30 degrees below the antenna 100.

  As described above, according to the present embodiment, it is possible to adjust the direction of the main beam only by moving the reflector 2 in the vertical direction of the antenna 100 with respect to the radiator 1.

<Modification>
The installation location of the antenna 100 of the present embodiment is not particularly limited to the top of the utility pole. The antenna 100 of the present embodiment is advantageous in that it is small in size and can change the direction of the main beam. For this reason, the antenna 100 of this Embodiment can be installed in various places.

  FIG. 21 is a diagram illustrating a first modification of the antenna according to the present embodiment. Referring to FIG. 21, antenna 100 is stored in storage container 200. The storage container 200 is attached to the wall surface 320 of the building by the attachment member 210.

  For example, the antenna 100 retransmits a television broadcast signal to an area that is behind a tall building and cannot directly receive radio waves transmitted from a television broadcast station or the like. For example, a reception antenna (not shown) for receiving radio waves transmitted from a television broadcasting station or the like is provided on the roof of the building. A retransmission device 120 is provided in the middle of the transmission line 140 that transmits a television broadcast signal from the receiving antenna to the antenna 100. The re-transmission device 120 supplies a television broadcast signal whose power is equal to or less than a desired value to the antenna 100 via the transmission line 140. The antenna 100 retransmits the television broadcast signal to an area behind the building.

  FIG. 22 is a diagram illustrating a second modification of the antenna of the present embodiment. Referring to FIG. 22, antenna 100A is different from antenna 100 shown in FIG. 2 in that it is not bent into a cylindrical shape. The shape of the storage container 200A that stores the antenna 100A is a rectangular parallelepiped. Note that the storage container 200 </ b> A is attached to the wall surface 320 of the building by the attachment member 210 as in the modification shown in FIG. 21.

  The height of the storage containers 200 and 200A from the ground is not particularly limited, but is, for example, approximately the same as (or higher than) the height of the utility pole 300 in FIG.

  FIG. 23 is a diagram illustrating a configuration example of the antenna 100A of FIG. Referring to FIG. 23, position adjusting unit 3 includes insulating substrates 31 and 32. On main surface 31A of insulating substrate 31, radiator 1 (loop element 11 and parasitic element 12) is formed. The reflector 2 is formed on the main surface 32 </ b> A of the insulating substrate 32. The reflector 2 may be formed on the surface of the insulating substrate 32 opposite to the main surface 32A.

  A plurality of holes 4 </ b> A are formed in the insulating substrate 31. The bolt 5 is passed through the hole 4A and connected to a nut (not shown). Main surfaces 31A and 32A are parallel. The insulating substrate 32 can be moved in the direction along the main surface 31A of the insulating substrate 31 by changing the hole through which the bolt 5 of the plurality of holes 4A passes. Thereby, the reflector 2 can be moved in the vertical direction with respect to the radiator 1.

  Further, the shape of the radiator and reflector of the antenna of the present embodiment is not limited as shown in FIG.

  FIG. 24 is a diagram showing a modification of radiator 1 shown in FIG. Referring to FIG. 24, radiator 1A is a loop element formed by bending a conductor rod (which may be a tube) into a circle. Such a loop element can also be used as a radiator of the antenna 100 of this embodiment.

  FIG. 25 is a diagram illustrating a first modification of the reflector included in the antenna 100 of the present embodiment. FIG. 26 is a diagram illustrating a second modification of the reflector included in the antenna 100 of the present embodiment. Referring to FIGS. 25 and 26, reflector 2 </ b> A is formed in a loop shape similarly to parasitic element 12. The reflector 2B is, for example, a plate-like conductor that has been hollowed out. The reflector 2B may be formed by arranging a plurality of conductor rods at equal intervals, connecting one ends of the plurality of rods with a conductor, and connecting the other ends of the plurality of rods with a conductor. . These reflectors can also be used as the reflector of the antenna 100 of this embodiment.

  In the present embodiment, the reflector is movable in a predetermined direction, but the radiator may be movable, or both the radiator and the reflector may be movable. In this case, the same effect as that obtained by the antenna 100 can be obtained.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure explaining the example of installation of the antenna 100 which concerns on embodiment of this invention. It is a figure explaining the structure of the antenna 100 of FIG. It is an expanded view of the radiator 1 shown in FIG. It is the figure which looked at only the radiator 1 among the components of the antenna 100 shown in FIG. 2 along the X direction, the Y direction, and the Z direction. FIG. 4 is a diagram for explaining the positional relationship between the antenna main surface, the horizontal plane, and the vertical plane of the loop element 11. It is a figure which shows the gain of the radiator. It is a figure which shows VSWR of the radiator 1. FIG. It is a figure which shows the front-back ratio and the half value width of the radiator. It is a figure which shows the directivity of the radiator 1 on a horizontal surface. It is a figure which shows the directivity of the radiator 1 on a vertical surface. It is the figure which looked at the radiator 1 and the reflector 2 shown in FIG. 2 along the X direction, the Y direction, and the Z direction. It is a figure which shows the gain of the front direction of the antenna 100 (no tilt). It is a figure which shows VSWR of the front direction of the antenna 100 (no tilt). It is a figure which shows the front-back front-back ratio and half value width of the antenna 100 (no tilt). It is a figure which shows the directivity of the antenna 100 (no tilt) on a horizontal surface. It is a figure which shows the directivity of the antenna 100 (no tilt) on a vertical surface. It is the figure which looked at the antenna 100 (with a tilt) along the X direction, the Y direction, and the Z direction. It is a figure which shows the gain in the front and diagonally downward of the antenna 100 (with a tilt). It is a figure which shows the directivity of the antenna 100 (with a tilt) on a horizontal surface. It is a figure which shows the directivity of the antenna 100 (with a tilt) on a vertical surface. It is a figure which shows the 1st modification of the antenna of this Embodiment. It is a figure which shows the 2nd modification of the antenna of this Embodiment. It is a figure which shows the structural example of the antenna 100A of FIG. It is a figure which shows the modification of the radiator 1 shown in FIG. It is a figure which shows the 1st modification of the reflector contained in the antenna 100 of this Embodiment. It is a figure which shows the 2nd modification of the reflector contained in the antenna 100 of this Embodiment.

Explanation of symbols

  1,1A radiator, 2,2A, 2B reflector, 3 position adjusting part, 4 slide groove, 4A hole, 5 bolt, 6 nut, 11 loop element, 12 parasitic element, 15 central axis, 21 inner wall, 22 outer wall , 31, 32 Insulating substrate, 31A, 32A Main surface, 100, 100A antenna, 120 Retransmission device, 140 Transmission line, 200, 200A Storage container, 210 Mounting member, 300 Utility pole, 320 Wall surface, 400 General household, 410 Antenna, 420 TV receiver, A plane, FD1, FD2 feed point, OA, OB center, S radio wave.

Claims (5)

A radiator,
A reflector,
A position adjusting unit to which the radiator and the reflector are attached, and an attachment position of at least one of the radiator and the reflector can be adjusted along a predetermined direction ;
The position adjustment unit is an insulating cylinder.
The predetermined direction is a direction along the central axis of the cylindrical body,
The radiator is attached to the inner wall in a state bent along the inner wall of the cylindrical body,
The antenna , wherein the reflector is attached to the outer wall while being bent along the outer wall of the cylinder . A radiator,
A reflector,
A position adjusting unit to which the radiator and the reflector are attached, and an attachment position of at least one of the radiator and the reflector can be adjusted along a predetermined direction;
The position adjusting unit is
A first insulating substrate having a first main surface;
A second insulating substrate that is movable in a direction along the first main surface and has a second main surface parallel to the first main surface;
The radiator is formed on the first main surface;
The reflector is an antenna formed on the second main surface . The predetermined direction is a vertical direction of the antenna in the installed state of the antenna, antenna according to claim 1 or 2. The antenna according to any one of claims 1 to 3, wherein the position adjusting unit fixes the mounting position of the radiator and can adjust the mounting position of the reflector. The radiator includes a loop element, the antenna according to any one of claims 1 4.

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