Leakage coaxial cable

Abstract

To provide a leakage coaxial cable that can be easily laid in a short time.SOLUTION: A leakage coaxial cable 1A of one embodiment has: an upper leakage coaxial cable 11; a support wire 40 located above the upper leakage coaxial cable 11; a lower leakage coaxial cable 12 located below the upper leakage coaxial cable 11; and a connecting part 30 that is located between the upper leakage coaxial cable 11 and the lower leakage coaxial cable 12, and integrates the upper leakage coaxial cable 11 and the lower leakage coaxial cable 12 with each other. The upper leakage coaxial cable 11, the lower leakage coaxial cable 12, the support wire 40, and the connecting part 30 are arranged in parallel. The upper leakage coaxial cable 11 and the lower leakage coaxial cable 12 each include a sheath 24 that forms an outermost layer. A sheath 24a of the upper leakage coaxial cable, a sheath 24b of the lower leakage coaxial cable 12, and the connecting part 30 are molded integrally of a resin material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a leaky coaxial cable. [Background technology]

[0002] A type of coaxial cable known as leaky coaxial cable is one that is installed in areas where radio waves cannot be detected (for example, inside tunnels or underground shopping malls). A leaky coaxial cable has multiple holes (slots) along its length, and radio waves are emitted through these slots. Therefore, by installing a leaky coaxial cable in an area where radio waves cannot be detected, it is possible to deliver radio waves to the area and reduce the area where radio waves cannot be detected.

[0003] A leaky coaxial cable has an integrated support wire (commonly called a "messenger wire"), and is attached to the ceiling or wall of a blind area using this support wire. For example, the support wire of a leaky coaxial cable is connected to a support fixed to the ceiling or side wall of a tunnel. As a result, the leaky coaxial cable is suspended from the ceiling or side wall of the tunnel. From another perspective, in order to lay a leaky coaxial cable, it is necessary to connect the support fixed to the ceiling or side wall of the tunnel to the support wire of the leaky coaxial cable.

[0004] Patent Document 1 discloses a composite leaky coaxial cable having two leaky coaxial cables arranged in parallel and a suspension support wire arranged in parallel between the two leaky coaxial cables. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-106845 Summary of the Invention [Problem to be solved by the invention]

[0006] It is desirable that a leaky coaxial cable be easy to install in a short time. [Means for solving the problem]

[0007] A leaky coaxial cable according to one embodiment includes a first leaky coaxial cable, a support wire located on one radial side of the first leaky coaxial cable, a second leaky coaxial cable located on the other radial side of the first leaky coaxial cable, and a connection portion located between the first leaky coaxial cable and the second leaky coaxial cable and integrating the first leaky coaxial cable and the second leaky coaxial cable. The first leaky coaxial cable, the second leaky coaxial cable, the support wire, and the connection portion are arranged in parallel, and the first leaky coaxial cable and the second leaky coaxial cable have sheaths that form the outermost layers. The sheath of the first leaky coaxial cable, the sheath of the second leaky coaxial cable, and the connection portion are integrally molded from a resin material. Effect of the Invention

[0008] According to the present invention, a leaky coaxial cable that can be easily installed in a short time is realized. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view showing an end portion of a leaky coaxial cable according to an embodiment of the present invention; [Diagram 2] 1 is an enlarged cross-sectional view of a leaky coaxial cable according to an embodiment of the present invention; [Diagram 3] FIG. 13 is a bottom view of the upper and lower leaky coaxial cables showing the location of the slots. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all drawings referred to in describing the embodiment, the same or substantially the same configurations and elements are designated by the same reference numerals. In addition, as a rule, once a configuration or element has been described, it will not be described repeatedly.

[0011] <Outline of leaky coaxial cable> Fig. 1 is a side view showing an end of a leaky coaxial cable 1A according to the present embodiment. Fig. 2 is an enlarged cross-sectional view of the leaky coaxial cable 1A according to the present embodiment. The cross section shown in Fig. 2 is taken along line AA in Fig. 1.

[0012] The leaky coaxial cable 1A according to the present embodiment is a composite leaky coaxial cable having two integrated leaky coaxial cables. More specifically, the leaky coaxial cable 1A is an omnidirectional composite leaky coaxial cable having an integrated first leaky coaxial cable 11 and a second leaky coaxial cable 12.

[0013] The leaky coaxial cable 1A has a first leaky coaxial cable 11 and a second leaky coaxial cable 12, as well as a connection part 30 and a support wire 40. The first leaky coaxial cable 11, the second leaky coaxial cable 12, the connection part 30 and the support wire 40 are arranged in parallel and integrated.

[0014] The support wire 40 is located on one radial side of the first leaky coaxial cable 11, and the second leaky coaxial cable 12 is located on the other radial side of the first leaky coaxial cable 11.

[0015] Here, if the side of the first leaky coaxial cable 11 and the second leaky coaxial cable 12 on which the support wire 40 is located is defined as the "upper side" and the side opposite to the side on which the support wire 40 is located is defined as the "lower side", then the first leaky coaxial cable 11 is disposed above the second leaky coaxial cable 12, and the support wire 40 is disposed above the first leaky coaxial cable 11. In other words, the first leaky coaxial cable 11 is disposed below the support wire 40, and the second leaky coaxial cable 12 is disposed below the first leaky coaxial cable 11.

[0016] In the following description, the first leaky coaxial cable 11 may be referred to as the "upper leaky coaxial cable 11" and the second leaky coaxial cable 12 may be referred to as the "lower leaky coaxial cable 12".

[0017] <Upper leaky coaxial cable / Lower leaky coaxial cable> The upper leaky coaxial cable 11 and the lower leaky coaxial cable 12 have substantially the same structure. Specifically, the upper leaky coaxial cable 11 and the lower leaky coaxial cable 12 each include a central conductor 20, an insulator 21, an outer conductor 22, a retaining tape 23, and a sheath 24. The outer conductor 22 is provided with a plurality of slots 25.

[0018] <Center conductor> Each of the central conductors 20 has a pipe (tube) shape. More specifically, each of the central conductors 20 is a straight copper pipe. However, the shape of the central conductors 20 is not limited to a straight shape, and the material of the central conductors 20 is not limited to copper.

[0019] For example, the central conductor 20 can be replaced with a spiral copper pipe, or a straight or spiral aluminum pipe. The central conductor is sometimes called the "inner conductor."

[0020] <Insulator> Each insulator 21 is provided around the central conductor 20. From another perspective, the insulators 21 form an insulating layer that covers the outer circumferential surface of the central conductor 20.

[0021] The insulator 21 is made of a foamed resin or a material containing a foamed resin. From the viewpoint of suppressing dielectric loss due to the insulator 21, it is preferable to form the insulator 21 from an uncrosslinked resin material. More specifically, the material of the insulator 21 is preferably an uncrosslinked polyolefin resin, and more preferably an uncrosslinked polyethylene.

[0022] The insulator 21 of this embodiment is formed from a material that is a mixture of 100 parts by mass of PE (polyethylene) as a base resin, 0.005 parts by mass of ADCA (azodicarbonamide) as a foam core material, and 0.01 parts by mass of OBSH (oxybisbenzenesulfonylhydrazide).

[0023] From the viewpoint of suppressing dielectric loss due to the insulator 21, the foaming degree of the insulator 21 is preferably 70% to 85%, and more preferably about 80%.

[0024] In order to improve the adhesion between the central conductor 20 and the insulator 21, an internal solid layer may be provided between them. The internal solid layer is preferably made of a non-foamed resin (e.g., polyethylene). The thickness of the internal solid layer is preferably about 0.1 mm.

[0025] From the viewpoint of suppressing the generation of toxic gases during combustion, it is preferable to form the insulator 21 from a non-halogen resin that does not contain halogen elements such as fluorine or chlorine. Furthermore, additives may be added to the material forming the insulator 21 as necessary.

[0026] <Outer conductor> Each of the outer conductors 22 is provided around the insulator 21. More specifically, the outer conductors 22 are formed of a conductive tape (aluminum tape) wound around the outer circumferential surface of the insulator 21.

[0027] A plurality of slots 25 are provided at regular intervals in the aluminum tape forming the outer conductor 22. Each slot 25 is approximately rectangular, with its four corners rounded.

[0028] The aluminum tape forming the outer conductor 22 of the upper leaky coaxial cable 11 is wound around the outer surface of the insulator 21 of the upper leaky coaxial cable 11 so that each slot 25 is positioned at a predetermined position on the upper leaky coaxial cable 11.

[0029] Similarly, the aluminum tape forming the outer conductor 22 of the lower leaky coaxial cable 12 is wrapped around the outer surface of the insulator 21 of the lower leaky coaxial cable 12 so that each of the slots 25 is positioned at a predetermined position on the lower leaky coaxial cable 12.

[0030] 3 is a bottom view of the upper leaky coaxial cable 11 and the lower leaky coaxial cable 12, showing the position of the slot 25. Note that in FIG. 3, for convenience's sake, the lower leaky coaxial cable 12 is made shorter than the upper leaky coaxial cable 11, but in reality the lower leaky coaxial cable 12 has the same length as the upper leaky coaxial cable 11.

[0031] 1 and 3, each of the slots 25 provided in the outer conductor 22 of the upper leaky coaxial cable 11 is located below the upper leaky coaxial cable 11. Similarly, each of the slots 25 provided in the outer conductor 22 of the lower leaky coaxial cable 12 is located below the lower leaky coaxial cable 12.

[0032] More specifically, the center P (FIG. 3) of each slot 25 provided in the outer conductor 22 of the upper leaky coaxial cable 11 is located below the central axis C1 (FIG. 1) of the upper leaky coaxial cable 11. Also, the center P (FIG. 3) of each slot 25 provided in the outer conductor 22 of the lower leaky coaxial cable 12 is located below the central axis C2 (FIG. 1) of the lower leaky coaxial cable 12. The center P of the slot 25 is the intersection of the diagonals of the slot 25.

[0033] From another perspective, the slot 25 of the upper leaky coaxial cable 11 is disposed at a position 180 degrees different from the supporting wire 40 in the circumferential direction of the upper leaky coaxial cable 11. Also, the slot 25 of the lower leaky coaxial cable 12 is disposed at a position 180 degrees different from the supporting wire 40 in the circumferential direction of the lower leaky coaxial cable 12.

[0034] From yet another perspective, the slots 25 of the upper leaky coaxial cable 11 are disposed at a position on the upper leaky coaxial cable 11 that is farthest from the support wire 40. Also, the slots 25 of the lower leaky coaxial cable 12 are disposed at a position on the lower leaky coaxial cable 12 that is farthest from the support wire 40. As a result, the radio waves radiated from the respective slots 25 are less susceptible to the influence of the support wire 40, which is a conductor.

[0035] The outer conductor 22 may be formed of copper tape or other conductive tape. The shape, size, pitch, etc. of the slots 25 may be appropriately changed depending on the frequency of the radio waves radiated from the slots 25. For example, the shape of the slots 25 may be elliptical. In this case, the center P of the slot 25 is the intersection of the major axis and minor axis of the slot 25.

[0036] <Retaining tape> Each of the pressure winding tapes 23 is a PET tape (polyethylene terephthalate tape) and is wound around the outer circumferential surface of the outer conductor 22. From another perspective, the pressure winding tape 23 is wound over the conductive tape that forms the outer conductor 22. However, the pressure winding tape 23 is not limited to a polyethylene terephthalate tape.

[0037] <Sheath> Each sheath 24 is provided around the winding tape 23 and forms the outermost layer of the cable. More specifically, the sheath 24 of the upper leaky coaxial cable 11 forms the outermost layer of the upper leaky coaxial cable 11. Similarly, the sheath 24 of the lower leaky coaxial cable 12 forms the outermost layer of the lower leaky coaxial cable 12.

[0038] In the following description, the sheath 24 forming the outermost layer of the upper leaky coaxial cable 11 may be referred to as the "sheath 24a" and the sheath 24 forming the outermost layer of the lower leaky coaxial cable 12 may be referred to as the "sheath 24b" to distinguish them from each other. However, this distinction is made merely for the convenience of description.

[0039] The sheath 24a is formed of a resin material extruded around the holding and winding tape 23 of the upper leaky coaxial cable 11. The sheath 24b is formed of a resin material extruded around the holding and winding tape 23 of the lower leaky coaxial cable 12. More specifically, the sheaths 24a and 24b are integrally formed from flame-retardant polyethylene extruded around the respective holding and winding tapes 23 at the same time.

[0040] <Connection> The connection portion 30 is located between the upper leaky coaxial cable 11 and the lower leaky coaxial cable 12. According to the above-mentioned definition, the connection portion 30 is located between the upper leaky coaxial cable 11 and the lower leaky coaxial cable 12 in the vertical direction.

[0041] The connection part 30 integrates the upper leaky coaxial cable 11 and the lower leaky coaxial cable 12 over the entire length or approximately the entire length. More specifically, the connection part 30 connects the sheath 24a of the upper leaky coaxial cable 11 and the sheath 24b of the lower leaky coaxial cable 12 over the entire length or approximately the entire length.

[0042] The connection part 30 is a strip-shaped resin part that is molded simultaneously with the sheath 24 and is integrated with the sheath 24. In other words, the sheath 24 is molded from a part of the resin material extruded around the holding and winding tape 23, and the connection part 30 is molded from another part of the resin material extruded around the holding and winding tape 23, and the sheath 24 and the connection part 30 are connected without interruption.

[0043] More specifically, the lower portion of the sheath 24a is seamlessly connected to one side of the connecting portion 30, and the upper portion of the sheath 24b is seamlessly connected to the other side of the connecting portion 30.

[0044] Here, the width W (FIG. 2) of the connection portion 30 corresponds to the distance between the upper leaky coaxial cable 11 and the lower leaky coaxial cable 12. Therefore, by changing the width W of the connection portion 30, it is possible to adjust the distance between the upper leaky coaxial cable 11 and the lower leaky coaxial cable 12. For example, by expanding the width W of the connection portion 30, the distance between the upper leaky coaxial cable 11 and the lower leaky coaxial cable 12 is increased, and interference of radio waves is more reliably avoided.

[0045] On the other hand, if the width W of the connection part 30 is expanded, there is a risk that the wind pressure received by the connection part 30 will increase. For example, if the leaky coaxial cable 1A is laid inside a tunnel, the connection part 30 will be subjected to wind induced by vehicles traveling inside the tunnel. The wider the width W of the connection part 30, the stronger (higher) the wind pressure received by the connection part 30 will be.

[0046] Therefore, in this embodiment, a plurality of ventilation holes 31 are provided in the connection part 30. The plurality of ventilation holes 31 are arranged in a row along the longitudinal direction of the connection part 30. From another perspective, the connection part 30 has a plurality of openings provided along its longitudinal direction. As a result, the wind pressure received by the connection part 30 is reduced.

[0047] The shape of the ventilation holes 31 is not limited to a rectangle. The number, position, size, pitch, etc. of the ventilation holes 31 can be changed as appropriate.

[0048] <Support line> The support wire 40 is integrated with the upper leaky coaxial cable 11, the lower leaky coaxial cable 12, and the connection portion 30. More specifically, the support wire 40 is a metal wire, and is covered with a covering portion 41 that is connected to the sheath 24. More specifically, the lower portion of the covering portion 41 that covers the support wire 40 is seamlessly connected to the upper portion of the sheath 24a.

[0049] The covering portion 41 is a resin portion that is molded simultaneously with the sheath 24 and the connection portion 30 and is integrated therewith. In other words, the sheath 24 is molded from a part of the resin material extruded around the holding and winding tape 23, the connection portion 30 is molded from another part of the resin material extruded around the holding and winding tape 23, and the covering portion 41 is molded from yet another part of the resin material extruded around the holding and winding tape 23. As a result, the sheath 24, the connection portion 30, and the covering portion 41 are seamlessly connected.

[0050] As described above, the sheath 24, the connection portion 30 and the covering portion 41 are a single resin portion molded simultaneously, and are seamlessly connected to one another.

[0051] <How to lay leaky coaxial cable> The leaky coaxial cable 1A is attached to the ceiling or wall of a tunnel or an underground mall using a support wire 40. For example, the leaky coaxial cable 1A is suspended from the side wall of a tunnel by connecting the support wire 40 to a support that is fixed to the side wall of the tunnel in advance. As a result, two leaky coaxial cables (upper leaky coaxial cable 11 and lower leaky coaxial cable 12) are laid in the tunnel at the same time.

[0052] At this time, since the support wire 40 is located above the upper leaky coaxial cable 11, the support tool and the support wire 40 can be easily connected in a short time compared to the case where the support wire 40 is located between the upper leaky coaxial cable 11 and the lower leaky coaxial cable 12. In other words, by using the leaky coaxial cable 1A according to this embodiment, multiple leaky coaxial cables can be easily laid in a short time.

[0053] Diversity reception can be realized by laying a leaky coaxial cable 1A including an integrated upper leaky coaxial cable 11 and a lower leaky coaxial cable 12. Specifically, the radio wave receiving sensitivity can be improved by selecting either the radio wave received by the upper leaky coaxial cable 11 or the radio wave received by the lower leaky coaxial cable 12, or by combining both radio waves.

[0054] In addition, it is possible to improve throughput by using MIMO (Multi-Input Multi-Output) transmission and reception, and to simultaneously create service areas using different frequency bands.

[0055] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Furthermore, all materials and numerical values ​​described in this specification are merely examples, and can be modified as appropriate. [Explanation of symbols]

[0056] 1A: Leaky coaxial cable 11: First leaky coaxial cable (upper leaky coaxial cable) 12: Second leaky coaxial cable (lower leaky coaxial cable) 20: Center conductor 21: Insulator 22: Outer conductor 23: Holding tape 24, 24a, 24b: Sheath 25: Slot 30: Connection 31: Ventilation hole 40: Support line 41: Covering part C1,C2: Central axis W: Width

Claims

1. a first leaky coaxial cable; a support wire located on one radial side of the first leaky coaxial cable; a second leaky coaxial cable located on the other radial side of the first leaky coaxial cable; a connection portion located between the first leaky coaxial cable and the second leaky coaxial cable, for integrating the first leaky coaxial cable and the second leaky coaxial cable, the first leaky coaxial cable, the second leaky coaxial cable, the support wire, and the connection portion are arranged in parallel, The first leaky coaxial cable and the second leaky coaxial cable each have a sheath forming an outermost layer, The sheath of the first leaky coaxial cable, and the sheath and the connecting portion of the second leaky coaxial cable are integrally molded from a resin material.

2. A covering portion covering the support wire is provided.

2. The leaky coaxial cable according to claim 1, wherein the sheath of the first leaky coaxial cable, the sheath of the second leaky coaxial cable, the connection portion and the coating portion are integrally formed from a resin material.

3. 2. The leaky coaxial cable according to claim 1, wherein the connection portion is provided with a plurality of ventilation holes arranged along the longitudinal direction thereof.

4. The first leaky coaxial cable and the second leaky coaxial cable each include a central conductor, an insulator provided around the central conductor, an outer conductor provided around the insulator, and a plurality of slots provided in the outer conductor; When the side on which the support wire is located with respect to the first leaky coaxial cable and the second leaky coaxial cable is defined as an upper side, and the side opposite to the side on which the support wire is located is defined as a lower side, a center of each of the slots of the first leaky coaxial cable is located below a central axis of the first leaky coaxial cable; The leaky coaxial cable according to claim 1 , wherein the center of each of the slots provided in the second leaky coaxial cable is located below a central axis of the second leaky coaxial cable.

Images