JP2007266994A - Antenna extension method and antenna for extension - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To install a new antenna to an existing antenna tower at low cost. <P>SOLUTION: A bottom support which supports the bottom of a first column support 12 is removed with the first column support 12 of an existing first antenna A1 temporarily supported to a tower body 10. After removing, a second column support 84 of a second antenna for extension is connected to the first column support 12, and the second column support 84 is supported to the tower body 10. Subsequently, the upper part of the tower body 10 is removed and the proper part of the second column support 84 is opened. A second antenna body is attached to the second column support 84 and the second antenna is completed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of adding another antenna to an antenna tower in which an antenna is installed at the top of the tower body, and an antenna suitable for the addition.

  In recent years, digitalization of broadcasting and communication is progressing rapidly, and in particular, recently, digital broadcasting of television is being started. However, it is very expensive to newly install an antenna tower for digital communication / broadcasting in addition to the existing antenna tower for analog communication / broadcasting. Moreover, it is not easy to secure a place for installing a new antenna tower.

  Therefore, in recent years, measures have been taken to add a digital antenna to an existing analog antenna tower so that the antenna main body of the antenna tower can be used as both an analog antenna and a digital antenna. Specifically, an antenna to be newly installed (digital antenna) is interposed between the existing antenna (analog antenna) and the top of the tower body that supports the antenna, and this new antenna is the above-mentioned existing antenna. Measures are taken such that the structure is supported from below.

  However, in the past, as a concrete method for adding a new antenna as described above, once the existing antenna is lowered from the top of the tower and a new antenna is installed at the top of the tower, the existing antenna is newly installed on the new antenna. Therefore, a large-scale facility such as a large crane is required for the construction. Moreover, since the existing antenna is completely removed during the construction, it becomes impossible to broadcast, so in order to add more antennas without interrupting broadcasting, for example, in a limited time zone such as midnight or early morning The construction has to be completed, and such severe restrictions on the construction period result in a significant burden on the operator.

  In order to eliminate such inconveniences, Patent Document 1 discloses a method for adding antennas without interrupting broadcasting using existing antennas. This method is performed in the following procedure.

  1) A temporary iron tower is constructed in the section necessary for installing the additional antenna at the upper part of the existing antenna tower, and the pillar of the existing antenna is fixed to this temporary iron tower.

  2) The part of the existing steel tower inside the said temporary iron tower is removed.

  3) A new antenna column, that is, a new column is connected to the existing antenna column, and this new column is supported by the existing tower.

4) Remove the temporary tower and attach a new antenna body to the new column.
JP 2004-332347 A

  The method described in Patent Document 1 fixes an existing antenna column to a newly constructed temporary tower, then removes the existing tower portion inside the temporary tower, and then installs a new column on the existing column. Since they are connected, the steel tower must be constructed over a relatively long section required for the installation of a new antenna. Therefore, there are many costs such as material costs and man-hours required for constructing the temporary tower, and it is difficult to reduce costs and work time accordingly.

  The present invention aims to solve such problems.

  As means for solving the above-described problems, the present invention provides a first antenna having a first support column and a first antenna main body portion attached to the first support column, and a bottom support portion for supporting at least the bottom portion of the first support column. A method for adding a second antenna having a second support column and a second antenna main body portion attached to the second support column in a region below the first antenna with respect to the antenna tower having the tower main body having And the 1st removal process which removes the bottom support part in the state where the part above the bottom part among the 1st pillars is temporarily supported by the tower body, and after removing the bottom support part, The connecting step of connecting the second support of the second antenna to the bottom of the first support, and the second antenna body of the second support connected to the first support is attached to the tower body. Antenna pick A final support step of providing a final support portion for supporting a portion below the portion and supporting the second support on the final support portion; and a portion of the tower body above the final support portion. A second removal step of removing a portion located around the antenna attachment portion; and an antenna attachment step of attaching the second antenna main body to the second support post after the second removal step.

  In this method, after performing the first removal step of removing the bottom support portion in a state where the portion of the first support column above the bottom portion is temporarily supported by the tower body, the second antenna is conventionally used. Rather than constructing a temporary tower over the entire installation area and removing the existing tower portion in the same area, the connecting step of connecting the second support of the second antenna to the bottom of the support first, and the tower body And a final support step of providing the final support portion and supporting the second support column on the final support portion, and then performing a second removal step of removing a portion located around the antenna mounting portion. Therefore, until the second column is connected to the first column and the second column is finally supported on the tower body, the first column is supported on the tower top using the existing tower body. It is possible. Therefore, compared with the conventional case where a large temporary tower over the installation area of the second antenna is constructed, the material cost and the man-hour required for adding the second antenna are small.

  In the first removal step, the first support column needs to be temporarily supported. As a specific means for performing such temporary support, the first removal step may be performed before the first removal step. A temporary support step is provided in which a temporary support portion that temporarily supports a portion of the column above the portion supported by the bottom support portion is temporarily added to the tower body, and the temporary support portion temporarily supports the first column. Is effective. The temporary support portion is for supporting the first column on the existing tower body side, and is not based on the assumption that the existing tower portion is removed like the conventional temporary iron tower. The support portion does not need to be large as in the case of the temporary tower. What is necessary is just to remove this temporary support part at a said 2nd removal process.

  The temporary support step preferably includes a step of adding a temporary tower top including the temporary support to the top of the tower body. In that case, what is necessary is just to make it remove the part containing the said temporary tower top part in the said tower | column main body at a said 2nd removal process.

  On the other hand, as the connecting step, it is preferable to connect the upper portion of the second support column and the lower portion of the first support column in the vertical direction by raising the second support column through the inside of the tower body. In this step, the second support column can be simply connected to the first support column as it is by raising the second support column.

  As a specific connection mode, the second support column has a cylindrical portion opening upward at the upper portion thereof, and the connection step raises the second support column to raise the cylindrical portion. It is preferable to include an insertion step of inserting the lower portion of the first support column in the vertical direction inside. If such a fitting step is included, when the second support column is raised, the cylindrical portion of the second support column and the first support column are directly connected to each other so that both the support columns are reliably and easily connected. can do.

  Here, the cylindrical portion of the second strut has a strut receiving portion provided at a position away from the upper end by a specific distance and capable of contacting the lower end of the first strut, the fitting step As long as the lower part of the first support column is fitted inside the cylindrical part until the lower end of the first support column contacts the support column receiving unit, the lower end of the first support column and the support column receiving unit This contact prevents the first support column from being inserted too deeply into the tubular portion. Moreover, after the connection, the first support column is supported from below by the support column receiving portion.

  Further, the present invention is an antenna suitable for expansion as described above, and includes a second column connected to a lower portion of the first column, and a second antenna body portion attached to the second column, The second support column has a cylindrical portion that opens upward and into which the lower portion of the first support column can be fitted, and the cylindrical portion has the first portion at a position away from the upper end by a specific distance. A strut receiving portion capable of contacting the lower end of one strut is provided.

  In this extension antenna, a verticality adjustment mechanism is provided at the upper end of the cylindrical portion of the second column to adjust the verticality of the first column inserted into the cylindrical portion. Is more preferable. By using this verticality adjusting mechanism, the verticality of the first support coupled to the second support can be improved.

  As described above, according to the present invention, by adding the second antenna while effectively using the existing tower body, it is possible to effectively reduce costs, man-hours, and time required for the extension. is there.

  A preferred embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows an existing antenna tower (for example, an analog antenna tower) before a new antenna is added. The antenna tower includes a tower main body 10 and a first antenna (for example, an analog antenna) A1, and the first antenna A1 is supported upright on the top of the tower main body 10.

  The first antenna A1 includes a first support column 12 and a first antenna body 18 that extend in the vertical direction. In this embodiment, the first support column 12 is configured such that a lower column portion 14 and an upper column portion 16 are connected by a flange 20, and the first antenna body portion 18 is provided around the upper column portion 16. Is installed. A junction box 19 is attached to the upper portion of the lower column portion 14. The junction box 19 is for electrically distributing and connecting the first antenna body 18 and the feeder line 21. The power supply line 21 is kept in the wiring state even if the second antenna expansion work described later is performed.

  In addition, the said 1st support | pillar 12 may be comprised by the single pillar part over the full length.

  The lower column portion 14 is supported on the tower body 10 side via a bottom support member 22 and an intermediate support member 24.

  The bottom support member 22 is for supporting the bottom portion of the lower column portion 14 from below. As shown in FIGS. 2 (a) and 2 (b), a horizontal support member 22 is provided at the top of the tower body 10. It is installed on the directional beam member 26.

  The bottom support member 22 includes a horizontal substrate 28, a peripheral wall 30 standing at the center of the substrate 28, and a plurality of ribs 31 for supporting the peripheral wall 30 from the outside. 28 is detachably fixed on the beam member 26 with bolts or the like. The peripheral wall 30 has an inner diameter into which the bottom of the lower column portion 14 can be fitted, and through holes 32 penetrating the wall in the horizontal direction are provided at a plurality of locations aligned in the circumferential direction. And the bottom part of the said lower side pillar part 14 is inserted inside the said surrounding wall 30, and while it mounts on the said board | substrate 26, the volt | bolt 34 is inserted from the outer side with respect to each said through-hole 32, and the said lower side pillar part The bottom portion of the lower column portion 14 is supported in the upright posture by the bottom support member 22 by being fixed with an appropriate nut at a position where it is abutted against the outer peripheral surface of the bottom portion 14.

  The intermediate support member 24 is for supporting the intermediate portion of the lower column portion 14 from the outside in the radial direction, and is provided at the top of the tower body 10.

  3A and 3B, the intermediate support member 24 includes a pair of left and right substrates 38A and 38B, and semicircular peripheral walls 40A and 40B provided on the substrates 38A and 38B. And a plurality of ribs 41 for supporting the peripheral walls 40A, 40B from the outside. Each of the substrates 38A, 38B and the peripheral walls 40A, 40B may be integrally formed over the entire circumference, or may have a structure that is divided into left and right as illustrated. The substrates 38A, 38B and the peripheral walls 40A, 40B have a structure in which the peripheral walls 40A, 40B are formed in a cylindrical shape so as to penetrate the central portion of the substrates 38A, 38B in the vertical direction in this state. The substrates 38A and 38B are installed on the beam member 36 at the top of the tower body 10.

  The peripheral walls 40A and 40B have inner diameters through which the middle part of the lower column part 14 can be inserted, and the peripheral walls 40A and 40B have a plurality of through holes 42 that penetrate the walls in the horizontal direction. It is provided in the place. And while the intermediate part of the said lower side pillar part 14 is penetrated by the inner side space 39 of the said surrounding walls 40A and 40B, the volt | bolt 44 is inserted from the outer side with respect to each said through-hole 42, and the said lower side pillar part 14 of By fixing with an appropriate nut at a position where it abuts against the outer peripheral surface, the intermediate portion of the lower column portion 14 is supported from the radially outer side by the intermediate support member 24, and the bolt 44 is operated by operating the bolt 44. The perpendicularity of the first support column 12 can be adjusted.

  Next, a method for adding the second antenna (for example, digital antenna) A2 shown in FIG. 13 to the existing antenna tower will be described in the order of the steps.

1) Tower top temporary process (Figs. 4 and 5)
In this process, in anticipation of the removal of the bottom support member 22 in the subsequent first removal process, the upper end of the lower column part 14 of the first antenna A1 is connected to the tower body together with the next intermediate support member replacement process. 10 constitutes a temporary support step for temporary support. In this tower top temporary process, as shown in FIG. 4, a temporary tower top 50 is added to the top of the existing tower body 10, and a structure in which the upper end of the lower column part 14 is supported on the temporary tower top 50 is constructed. Is done.

  5A and 5B show a specific structure of the temporary tower top 50. FIG. In the illustrated example, the temporary tower top portion 50 has a frame structure including four column members 52 in the vertical direction and a connecting member 54 that connects upper end portions of the adjacent column members 52, and a pair of opposing pairs. A pair of first temporary support members 56 that are orthogonal to each other are spanned between the connecting members 54, and a pair of second temporary support members 58 that are orthogonal to the first temporary support members 56 are also suspended between the first temporary support members 56. Has been passed. And the upper end part of the said lower side pillar part 14 is temporarily supported on these temporary support members 56 and 58. FIG.

  This temporary support is performed using a flange portion 20 that connects the lower column portion 14 and the upper column portion 16 thereon. Specifically, a part of the fastening bolts attached to the flange portion 20 is replaced with the long bolt 60, and the end of the long bolt 60 is the first temporary support member 56 and the second temporary bolt. By being placed on the support member 58, the weight of the first antenna A1 including both the pillar portions 14 and 16 is supported from below.

2) Intermediate support member replacement process (FIG. 6)
The intermediate support member 24 is removed and removed. Instead, a new intermediate support member 68 for temporary support is installed at the top of the tower. The basic structure of the newly provided intermediate support member 68 is substantially the same as that of the intermediate support member 24. Therefore, this intermediate support member replacement step may be omitted, and the intermediate support member 24 may be used as a temporary support as it is. However, it is preferable that the new intermediate support member 68 has the above-described halved structure in view of the mounting operation.

  Alternatively, only the intermediate support member 24 may be removed and the temporary tower top 50 alone may be temporarily supported.

3) First removal step This step is a step of removing the bottom support member 22. After this step is completed, the lower column portion 14 and the upper column portion 16 constituting the first support column 12 are temporarily supported by the existing tower body 10 only through the temporary tower top 50 and the intermediate support member 68. It becomes a state. The temporary support of the first support column 12 by the existing tower main body 10 is continued until the subsequent second removal step.

4) Connection preparation process (Fig. 7)
This step is a step of preparing for the connection prior to connecting the second support column 80 of the second antenna A2 to the lower column portion 14 in the next connecting step. Specifically, in this process, an appropriate one of the beam members hung inside the tower body 10 is removed, and a cavity 72 (FIG. 7) for inserting the second support column 80 is secured. At the same time, an intermediate support member 76 for supporting the intermediate portion of the second support column 80 is installed on an appropriate beam member 74.

5) Connecting step (FIGS. 8 and 9)
This step is a step of connecting the second support column 80 of the second antenna A2 to the bottom of the lower column portion 14. In this embodiment, as shown in FIG. 8, the second support column 80 is pulled up in a vertical posture through the cavity 72 inside the tower body 10, and the lower column is moved in the conveying direction (vertical direction). It is connected with the part 14.

  The second support column 80 is also configured such that the lower column portion 83 and the upper column portion 84 are interconnected in the vertical direction via the flange portion 82. The upper column portion 84 is formed of a cylindrical tube, and the cylindrical tube is further divided into upper and lower portions, and the boundary portion is mutually connected by a combination of a weld 86 and a backing member 88 as shown in FIGS. It is joined. Accordingly, in this embodiment, the upper column portion 84 is a cylindrical portion. The inner diameter of the upper column portion 84 is slightly larger than the outer diameter of the lower column portion 14, and the lower column portion 14 can be fitted inside the upper column portion 84. By this insertion, the upper column portion 80 and the lower column portion 14 are connected.

  However, the cylindrical portion according to the present invention may not be a cylindrical tube, and for example, the upper column portion 84 may be a rectangular tube with a triangular, square, or polygonal cross section. Also in this case, the cross-sectional shape of the first support column only needs to correspond to the cross-sectional shape of the rectangular tube.

  Further, in this embodiment, at the height position immediately above the joint portion by the welding 86, as shown in FIG. 10A, the inner side surface of the upper column portion 84 is inward from the inner side surface. A protruding column receiving rib 90 protrudes. The column receiving rib 90 regulates the insertion depth of the lower column portion 14 by contacting the lower end of the lower column portion 14.

  Therefore, in this connection step, the lower column of the first column 12 is placed inside the upper column 84 of the second column 80 as the second column 80 is pulled up through the inside of the tower body 10. The portion 14 is inserted to a position where it abuts on the column receiving rib 90, and the both column portions 84, 14 are connected to each other by the insertion, and the first column 12 is connected to the column supporting rib 90 on the second column 80 side. It will be ready to be received from below.

  Furthermore, in this embodiment, a verticality adjusting mechanism as shown in FIG. 10B is provided at the upper end portion of the upper column portion 84. The verticality adjusting mechanism is for adjusting the verticality of the lower column portion 14 fitted into the upper column portion 84. Specifically, the upper end portion of the upper column portion 84 is provided with a plurality of through holes 84a arranged in the circumferential direction on the outer peripheral surface of the upper column portion 84 so as to be located radially outward of each through hole 84a. A nut 83 is fixed to the nut. Then, while screwing the bolt 85 into the nut 83, the nut 83 is further inserted into the through hole 84 a from the outside in the radial direction, and is appropriately rotated, so that the tip of the bolt 85 is inserted into the first support column 12. It is possible to adjust the perpendicularity of the first support column 12 by abutting against the outer peripheral surface of the lower column portion 14.

  Note that the inner diameter of the intermediate support member 76 is set so that the flange portion 82 of the second support column 80 can pass through the intermediate support member 76 during the connecting step.

  In this connection step, only the upper column part 84 of the second support column 80 is connected to the lower column part 14 of the first support column 12, and then the lower column part 83 is connected to the upper column part 84. You may make it connect via the flange part 82. FIG. Moreover, you may make this connection process parallel with the next last support process.

6) Final support process (Fig. 11)
This step is a step of installing a new bottom support member 78 on the beam member 77 at an appropriate height position of the tower body 10 and supporting the bottom portion of the second support column 80 by the bottom support member 78. The bottom support member 78 may be the same as the bottom support member 22 (the bottom support member that has already been removed in the first removal step) shown in FIGS. May be designed with high strength. Through this step, the second support column 80 is finally supported by the bottom support member 78 and the intermediate support member 76.

  In addition, the support location of the 2nd support | pillar 80 in this final support does not necessarily need to be the bottom part of the 2nd support | pillar 80, and should just be a location below the area | region where the below-mentioned 2nd antenna main-body part 92 is attached. . For example, a notch or a hole may be provided at an appropriate position below the second support column 80, and a support plate or a pin may be inserted into the notch to support the second support column 80.

7) Second removal step (FIGS. 11 and 12)
In this step, a portion 10 a (FIG. 11) located above the intermediate support member 76 in the tower main body 10 and around the attachment site of the second antenna main body 92 is replaced with the temporary tower top 50. It is a process of removing together. By this step, as shown in FIG. 12, the periphery of the upper column portion 84 of the second column 80 is opened.

8) Antenna mounting process (Fig. 13)
This step is a step of attaching the second antenna main body 92 of the second antenna A2 around the upper column portion 84 of the second support column 80. By mounting the second antenna main body 92, the second antenna A2 is completed, and the second antenna A2 is added between the first antenna A1 and the top of the tower main body 10.

  According to the method described above, it is possible to add the second antenna A2 below the first antenna A1 at the top of the tower while maintaining the broadcastable state. In addition, during the construction, the existing tower body 10 is used as it is to support the first antenna A1, and the second support 80 of the second antenna A2 is connected to the first support 12 of the first antenna A1. Since the part corresponding to the area where the second antenna A2 is installed is removed from the tower body 10 (second removal process), the upper part of the tower body 10 is removed first as before. Unlike the method of connecting struts to each other, it is not necessary to construct a temporary iron tower over a long region, and the cost can be effectively reduced correspondingly.

  In particular, as shown in the illustrated second support column 80, if a cylindrical part (upper column part 84 in the figure) is provided on the upper part and the first support column 12 can be inserted into the cylindrical part, this first support column 80 is used. The operation of raising the two struts 80 through the inside of the tower body 10 allows the second struts 80 and the first struts 12 to be easily and reliably connected, and the working efficiency is further increased.

  However, the connection structure of the support | pillars in this invention is not restricted to this, For example, both support | pillars may be fastened with a volt | bolt etc. in a flange part.

  Further, the present invention only needs to include at least the second support column, and does not prevent the third support column and the fourth support column from being added below the second support column. By adding these columns in the same manner as in “5) Connecting step”, it is possible to raise the second antenna A2 to a required height position. This construction method is effective, for example, when it is desired to further raise the height position of the digital antenna from the ground.

It is a front view which shows the existing antenna tower before a 2nd antenna is expanded in embodiment of this invention. (A) is a top view of the bottom support member provided in the said antenna tower, (b) is the front view. (A) is a top view of the intermediate support member provided in the said antenna tower, (b) is the partial cross section front view. It is a front view which shows the state after the temporary tower top part was expanded to the said antenna tower. (A) is a top view of the temporary tower top, and (b) is a front view thereof. It is a front view which shows the state after replacement | exchange of the intermediate support member of the said antenna tower. It is a front view which shows the preparatory process for the connection of the 2nd support | pillar of the 2nd antenna to the 1st support | pillar of the 1st antenna in the said antenna tower. It is a front view which shows the process in which the said 2nd support | pillar is connected with a said 1st support | pillar. It is a front view of the upper side pillar part of the said 2nd support | pillar. (A) is the figure which expanded the longitudinal cross-section of the A section of FIG. 9, (b) is a cross-sectional front view which shows the perpendicularity adjustment mechanism provided in the upper end part of the said upper side pillar part. It is a front view which shows the state by which the said 2nd support | pillar was connected with the said 1st support | pillar, and the bottom support member which supports this 2nd support | pillar was provided in the tower main body of the said antenna tower. It is a front view which shows the state from which the tower main body of the circumference | surroundings of the part to which a 2nd antenna main body part is attached to the said 2nd support | pillar among the said tower main bodies was removed. It is a front view which shows the state by which the said 2nd antenna main-body part was attached to the said 2nd support | pillar.

Explanation of symbols

A1 1st antenna A2 2nd antenna 10 Tower body 12 First support column 14 Lower column part 16 Upper column part 18 First antenna body part 22 Bottom support member 24 Intermediate support member 50 Temporary tower top part 56 First temporary support member 58 First 2 Temporary support member 76 Intermediate support member (final support part)
78 Bottom support member (final support part)
80 Second column 84 Upper column part (tubular part)
90 Prop receiving rib 92 Second antenna body

Claims (8)

For an antenna tower comprising a first antenna having a first pillar and a first antenna body attached to the first pillar, and a tower body having a bottom support part that supports at least the bottom of the first pillar, A method for adding a second antenna having a second support column and a second antenna body attached to the second support column in a region below the first antenna,
A first removal step of removing the bottom support portion in a state in which a portion above the bottom portion of the first support column is temporarily supported by the tower body;
A connecting step of connecting the second support of the second antenna to the bottom of the first support after removing the bottom support;
The tower body is provided with a final support part for supporting a part below the antenna mounting part to which the second antenna main body part is attached among the second pillars connected to the first pillar. A final support step of supporting the second support column in
A second removal step of removing a portion of the tower body above the final support portion and located around the antenna mounting portion;
An antenna adding method comprising: an antenna attaching step of attaching the second antenna main body to the second support post after the second removing step. In the antenna extension method according to claim 1,
Before the first removal step, a temporary support portion that temporarily supports a portion of the first support column that is above the portion supported by the bottom support portion is added to the tower main body, and the temporary support portion includes the temporary support portion. An antenna extension method comprising performing a temporary support step of temporarily supporting the first support column, and removing a portion of the tower body including the temporary support portion in the second removal step. In the antenna expansion method according to claim 2,
The temporary support step includes a step of adding a temporary tower top portion including the temporary support portion to the top portion of the tower body, and the second removal step includes a portion of the tower body including the temporary tower top portion. An antenna expansion method characterized by being removed. In the antenna extension method in any one of Claims 1-3,
The connecting step is to connect the upper part of the second column and the lower part of the first column in the vertical direction by raising the second column through the inside of the tower body. Method. In the antenna extension method according to claim 4,
The second support column has a cylindrical portion opening upward at an upper portion thereof, and the connecting step raises the second support column so that the lower portion of the first support column is placed inside the cylindrical portion. An antenna expansion method comprising an insertion step of inserting in the vertical direction. In the antenna extension method according to claim 5,
The cylindrical portion of the second support column has a support column receiving portion that is provided at a specific distance from the upper end of the second support column and can contact the lower end of the first support column. The antenna extension method is characterized in that the lower portion of the first support column is fitted inside the tubular portion until the lower end of the first support column comes into contact. For an antenna tower comprising a first antenna having a first pillar and a first antenna body attached to the first pillar, and a tower body having a bottom support part that supports at least the bottom of the first pillar, An additional antenna to be added to the area below the first antenna,
A second support coupled to the lower portion of the first support;
A second antenna body attached to the second support column,
The second support column has a cylindrical portion that opens upward and into which the lower portion of the first support column can be fitted, and the cylindrical portion is located at a position away from the upper end by a specific distance. An extension antenna, characterized in that a support post that can contact the lower end of the first support is provided. The additional antenna according to claim 7,
The upper end of the cylindrical portion of the second column is provided with a verticality adjusting mechanism for adjusting the verticality of the first column inserted into the cylindrical portion. antenna.

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