JP2005244759A - Leakage coaxial cable and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leakage coaxial cable which is flexible even without applying corrugating working thereto and has excellent VSWR characteristics and attenuation amount characteristics. <P>SOLUTION: A leakage coaxial cable comprises an inner conductor 1 and a tubular outer conductor 3 which is provided at an outer edge side of the inner conductor 1 via an insulator 2, the outer conductor 3 being formed with a slot 5. The outer conductor 3 is formed smoothly tubular while forming an overlapping portion 7 by curving a copper tape so that both side edges of the copper tape overlap with each other. The overlapping both side edges are fused with each other in a thermal fusing layer 8 formed on the copper tape. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a leaky coaxial cable and a method for manufacturing the same.

There is a leaky coaxial cable that is installed in a high-rise building, tunnel, underground mall, etc. and used as a transmission / reception antenna of a wireless communication system (see, for example, Non-Patent Document 1). As shown in FIG. 9, in the conventional leaky coaxial cable, the outer conductor 42 is corrugated to reduce stress on the outer conductor and slot due to bending, deformation of the cable cross section, etc. Reference 1).
In the conventional leaky coaxial cable shown in FIG. 9, a polyethylene string 43 is spirally wound around an inner conductor (center conductor) 41, and further covered with a polyethylene pipe 44 to provide an insulator (insulation). Core) 45 is formed. Then, an aluminum outer conductor 42 corrugated on the outer peripheral side of the insulator 45 is covered and fixed by wrapping with a glass string 46, and a sheath 47 made of polyethylene is covered on the outer peripheral side. The outer conductor 42 is periodically formed with slots (not shown) for radiating radio waves.

FIG. 10 is an overall view showing a conventional method for manufacturing a leaky coaxial cable. First, a corrugating machine 49 is used to corrugate an aluminum tape 40 having slots 48 periodically opened beforehand. Next, an insulator 45 having an inner conductor 41 drawn out from the drum as a center is wound by a belt former 50 in a vertically attached form with a corrugated aluminum tape 40, and the joining portion of the tape 40 is fixed. For this purpose, a glass string 46 is wound. Then, a sheath 47 made of polyethylene covers the outer peripheral side of the outer conductor 42 by the coating machine 51, and a wound coaxial cable is wound around the drum.
Toshihiko Kishimoto and Shin Sasaki “LCX Communication System” The Institute of Electronics, Information and Communication Engineers, August 20, 1982, p. 18-19 JP 2003-51713 A

In the production of a conventional leaky coaxial cable, a corrugated process is applied to an aluminum tape 40 in which a slot 48 is previously formed, and the outer conductor 42 is formed by forming it into a tubular shape. There is a problem that the slot punching dimension a in the tape state and the slot dimension b after corrugation shown in FIG. 11B are greatly different (deformed), and the characteristics change from the design values. This is because the whole is shrunk in the longitudinal direction by corrugation.
In addition, due to the influence of processing oil during corrugation processing, the characteristics of the manufactured leaky coaxial cable deteriorate, and the desired VSWR (voltage standing wave ratio) characteristic and attenuation characteristics in the high frequency range (2 GHz to 5.3 GHz) are obtained. There is a problem that the reliability of the sheath 47 and the insulator 45 is lowered.

  Further, since the outer conductor 42 formed into a tubular shape is wound and held by the glass string 46, the diameter of the outer conductor 42 becomes unstable, and the contact of the joining portion of the tape becomes unstable. Had an adverse effect. In particular, outdoors, there is a problem that the entire cable vibrates due to the wind, the fixation by the glass string 46 is loosened, and the diameter varies significantly.

As another manufacturing method, when the slot 48 is formed after the corrugated processing of the copper tape 40, the shape of the slot 48 is as designed, but due to the influence of the residue of processing oil (cooling water in the case of laser processing) There is a problem that the characteristics of the completed leaky coaxial cable deteriorate.
In addition, in order to form the predetermined slot 48 after the corrugation processing, new equipment is required, and there is a problem that product management becomes complicated and cost increases.
In addition to fixing the outer conductor 42 with the glass string 46, there is a method of welding the butt portion of the tape 40. For the welding, the outer conductor 42 needs to have a thickness of at least 0.3 mm. In this case, unless the leaky coaxial cable has a corrugated structure, flexibility cannot be achieved.

A leaky coaxial cable according to the present invention is a leaky coaxial cable comprising an inner conductor and a circular outer conductor provided with an insulator on the outer peripheral side of the inner conductor and having a slot formed therein. The outer conductor is formed into a smooth circular tube by bending the copper tape so that both side edges of the copper tape are overlapped, and the overlapped side edges are formed on the copper tape. In other words, they are mutually fused by the heat fusion layer.
The copper tape has a thickness of 0.05 mm to 0.2 mm. In addition, the slot is formed in a peripheral wall portion on the opposite side of the outer conductor across the axis center with respect to the outer conductor. A sheath is provided on the outer peripheral side of the outer conductor, and the outer diameter of the sheath is 4 mm to 30 mm.

The leaky coaxial cable manufacturing method according to the present invention also includes a copper tape in which an insulator is formed on the outer peripheral side of the inner conductor, a slot is previously penetrated, and a heat-sealing layer is formed on both sides. The insulator is wound in a vertical wrapping shape so as to match, an external conductor is formed, the overlapped side edges are fused with the heat-sealing layer, and then a sheath is placed around the outer conductor Cover.
Alternatively, an insulator is formed on the outer peripheral side of the inner conductor, and the insulator is vertically wound so that both side edges overlap each other on a copper tape in which a slot is previously penetrated and a heat fusion layer is formed. An outer conductor is formed, and a sheath material is coated on the outer periphery of the outer conductor to form a sheath layer. This is a method of fusing with a deposition layer. Furthermore, since the sheath layer and the outer conductor are bonded to each other through the heat fusion layer by this heat, the strength and flexibility of the manufactured leaky coaxial cable are further improved.

According to the present invention, the size, shape, and pitch of the slot of the leaky coaxial cable coincide with each other without changing from the slot punching size, shape, and pitch (design dimension) in the copper tape state. Characteristics as designed can be obtained. That is, the slot shape is not changed and deformed, and the slot shape can be stabilized.
Moreover, it can have sufficient flexibility even if corrugation is not performed. That is, it is possible to have the same flexibility as that of a conventional cable having the same diameter having a corrugated outer conductor. By forming slots in advance in the copper tape, it is not necessary to provide a slot forming machine in the cable manufacturing line, and a finished product can be obtained with fewer steps, thereby reducing costs.

In addition, since the outer conductor is fixed in a tubular shape by fusing with the heat-fusible layer, a leaky coaxial cable having a stable shape for a long period of time, high durability, and reliability can be obtained.
Since no corrugation and slot punching after corrugation are performed, the processing oil does not remain, the attenuation of the leaky coaxial cable does not deteriorate, and the desired VSWR characteristics and high frequency range (from 2 GHz to 5.3GHz) attenuation characteristics can be obtained.

FIG. 1 is a perspective view showing an embodiment of a leaky coaxial cable according to the present invention. This leaky coaxial cable is laid in a high-rise building, tunnel, underground mall, etc., and used as a transmission / reception antenna of a wireless communication system. The
FIG. 2 is a cross-sectional view thereof. In FIGS. 1 and 2, the leaky coaxial cable includes an inner conductor 1 and a circular outer conductor 3 provided on the outer peripheral side of the inner conductor 1 via an insulator 2. , And a slot 5 is formed in the outer conductor 3. Further, a sheath 4 is coated on the outer peripheral side of the outer conductor 3 to constitute a leaky coaxial cable.

That is, foamed polyethylene is extrusion-coated on the outer peripheral side of the inner conductor (center conductor) 1 made of a hollow metal (copper) small pipe to form the insulator 2. The outer conductor 3 is covered on the outer peripheral side of the insulator 2, and a sheath material such as polyethylene (solid polyethylene) is further covered on the outer peripheral side to form a sheath layer 4a (sheath 4). Note that slots 5 for radiating radio waves are formed in the outer conductor 3 periodically (at a predetermined pitch) along the cable axis C direction.
In addition to the embodiment of FIG. 1 and FIG. 2, although not shown, copper clad aluminum wire, copper wire, or a twisted combination of them can be used as the internal conductor 1, but the strength and cable characteristics are From the viewpoint, a metal (copper) pipe is preferable. Further, as the insulator 2, there is a form in which a polyethylene string or the like is wound around the outer periphery of the inner conductor 1 and further covered with a polyethylene pipe to form an insulator, but the number of parts, ease of manufacturing, and cost are reduced. From the viewpoint, a foamed polyethylene form is preferred.

The outer conductor 3 is formed into a smooth circular tube by bending the copper tape 6 in a circumferential shape so that both side edges 6a, 6a of the copper tape 6 are overlapped to form an overlapping portion 7. In the overlapping portion 7, the overlapped side edge portions 6 a and 6 a are fused and fixed to each other by a heat sealing layer 8 formed on the copper tape 6.
The overlapping dimension A (see FIG. 2) of the overlapping portion 7 is preferably 1 mm to 20 mm in terms of strength and cable characteristics, and more preferably 5 mm to 15 mm.
Accordingly, the outer conductor 3 has a stepped portion and a slot 5 by superposition, but the outer peripheral surface (inner peripheral surface) is smooth (without being corrugated) and is formed into a circular tube as a whole.

The copper tape 6 is a continuous strip member having a thin thickness T having a width determined by the diameter of the cable, and the thickness T of the copper tape 6 is the thickness of the peripheral wall of the external conductor 3.
The thickness T of the copper tape 6 is 0.05 mm to 0.2 mm, preferably 0.07 mm to 0.12 mm.

When the thickness T exceeds 0.2 mm, it becomes difficult to give the leaky coaxial cable flexibility, and it is difficult to work in laying, and the cost is increased. In addition, in the conventional leaky coaxial cable, when both side edges of the copper tape are butted and fixed by welding, it is necessary to newly introduce equipment such as a welding machine, which increases equipment costs. That is, according to the present invention, a leaky coaxial cable can be manufactured at low cost by a general technique without using advanced techniques.
On the other hand, if the thickness T is less than 0.05 mm, the copper tape 6 is likely to be damaged, and the cable characteristics may be adversely affected. That is, the scratch has the effect of the slot 5 that radiates radio waves.

  FIG. 3 is an enlarged cross-sectional view of the overlapping portion 7 of the copper tape 6, and a heat fusion layer 8 is formed on one surface of the copper tape 6, and the copper tape 6 has an axial center C in the longitudinal direction of the tape. As the direction, since the insulator 2 is wound in a vertical side-by-side shape and the side edges 6a and 6a are overlapped on the inside and outside, in the overlapping portion 7, the side edge 6a of the inner copper tape 6 and the outer copper tape A thermal fusion layer 8 is interposed between the side edge portions 6 a and the thermal fusion layer 8 is fixed to each other. In addition, what is necessary is just to form the heat sealing | fusion layer 8 with the heat sealing agent known conventionally.

4 and 5 show another embodiment. A laminate layer 11 and a heat fusion layer 8 are formed on one surface of the copper tape 6 in a laminated manner. Since the insulator 2 is wound in a vertically attached winding and the side edges 6a and 6a are overlapped on the inside and outside, the side edge 6a of the inner copper tape 6 and the side edge of the outer copper tape are overlapped at the overlapping portion 7. The laminate layer 11 and the thermal fusion layer 8 of the side edge 6a of the inner copper tape 6 are interposed between the thermal fusion layer 8 and the inner copper tape 6.
Therefore, it can be said that both side edges 6a, 6a of the copper tape 6 are mutually fused by the heat-sealing layer 8 formed on the one surface side of the copper tape 6 via the laminate layer 11.

The laminate layer 11 is made of, for example, a polyester film, and is bonded or fused to one surface side of the copper tape 6.
The laminate layer 11 is formed on the outer peripheral surface of the copper tape 6 when the copper tape 6 has a circular tube shape. Then, the heat sealing layer 8 is formed on the outer peripheral surface of the laminate layer 11. In other words, in FIG. 5, the upper copper tape 6 is bent in the direction of arrows B and B so that the upper copper tape 6 is on the inner peripheral side and the lower heat sealing layer 8 is on the outer peripheral side.
Thereby, the laminate layer 11 can function as a protective layer of the copper tape 6. The slot 5 is formed only in the copper tape 6.

Then, as shown in FIG. 4, the sheath layer 4a is formed on the entire outer periphery of the heat-sealing layer 8 on the outer peripheral side, and the heat at the time of forming the sheath layer 4a (of the sheath material covered) is formed. Heat) promotes the fusion of the side edge portions 6a, 6a of the overlapping portion 7 in the inner heat-bonding layer 8, and the outer heat-bonding layer 8 is connected to the sheath 4 over the entire circumference. The outer conductor 3 is firmly fixed, and the mutual adhesion is improved.
Moreover, from the copper tape 6 to the heat sealing | fusion layer 8 (including the laminate layer 11) can be called a copper laminate tape.

The slot 5 is a long hole formed periodically (at a predetermined pitch) along the axis C direction in the outer conductor 3, and the plurality of holes are preferably formed at the same time when the copper tape 6 is manufactured. . The copper tape 6 is provided with the heat-sealing layer 8 (and the laminate layer 11). However, the manufacturer of the copper tape 6 is subjected to slot drilling and cleaning (and processing oil, debris, etc.). Is removed), rust-proofing is performed, and the heat-sealing layer 8 is formed (by forming the laminate layer 11). Alternatively, the heat-sealing layer 8 may be formed by applying a heat-sealing agent to the copper tape 6 in which the slot 5 is previously formed in the production line of the leaky coaxial cable.
That is, in the leaky coaxial cable production line, there is no need to provide a slot drilling process (which generates a lot of time) in the line, and the influence of processing oil due to the drilling process can be eliminated.

  A plurality of slots 5 are formed at predetermined intervals along the longitudinal direction at a substantially central portion of the copper tape 6 in the left-right width direction. Then, both side edges 6a, 6a of the copper tape 6 are overlapped to form an overlapped portion 7, whereby the slot 5 is formed on the outer conductor 3 on the opposite peripheral wall with the overlapped portion 7 and the axis C interposed therebetween. Part (position where the overlapping part 7 faces). That is, the slot 5 is formed on the peripheral wall of the outer conductor 3 that is approximately 180 ° away from the overlapping portion 7.

  The outer conductor 3 is a smooth straight pipe (straight type) without being a corrugated pipe as in the prior art, and a sheath 4 is provided (covered) on the outer peripheral side of the outer conductor 3. The outer diameter D of the sheath 4 (sheath layer 4a) is 4 mm to 30 mm. In other words, this coincides with the diameter (outer diameter) of the leaky coaxial cable, and it can be said that the diameter of the leaky coaxial cable is 4 to 30 mm.

Next, the manufacturing method of this leaky coaxial cable will be described with reference to FIG.
First, the insulator 2 is formed on the outer peripheral side of the inner conductor 1. The insulator 2 is made of foamed polyethylene. The inner conductor 1 with the insulator 2 fitted thereon is wound around the first drum 12.
The second drum 13 is wound with a copper tape 6 having a slot 5 penetrating in advance and a heat fusion layer 8 formed thereon.

Then, the internal conductor 1 with the insulator 2 fitted outside is fed out from the first drum 12, and the copper tape 6 is fed out from the second drum 13, and both are continuously fed into the former 14.
In the former 14, the copper tape 6 is wound around the outer peripheral side of the insulator 2 while forming a circular tube. That is, as shown in the order of FIGS. 7 (a), (b), and (c), the insulator 2 is wound in a vertical wrapping manner so that both side edges 6a and 6a of the copper tape 6 are overlapped with each other, thereby forming a tubular shape. The outer conductor 3 is formed. Thereby, the overlapping portion 7 is linearly formed so as to be parallel to the cable axis C.

  The copper tape 6 is provided with a laminate layer 11 and a heat-sealing layer 8. The laminate layer 11 is disposed on the outer peripheral side with respect to the copper tape 6. The laminate layer 11 is formed on the outer peripheral surface 6, and the heat-sealing layer 8 is formed on the outer peripheral surface of the laminate layer 11. That is, in the former 14, the outer conductor 3 is formed with the heat-sealing layer 8 as the outermost layer (the heat-sealing layer 8 is on the outer peripheral side of the copper tape 6 portion).

  Then, the overlapped side edge portions 6 a and 6 a are fused in the former 14 by the heat fusion layer 8 previously formed on the copper tape 6. That is, the overlapping portion 7 is heated (warmed) by a heater (not shown) provided in the former 14, and the heat-sealing layer 8 of the side edge 6 a of the copper tape 6 on the inner diameter side is melted (melted). ), And the copper tape 6 overlapped (wrapped) on the outer diameter side is fused (thermally fused) to fix both side edges 6a and 6a.

The intermediate product fed from the former 14 is then fed into the coating machine 15. Then, the sheath 15 made of polyethylene covers the outer peripheral side of the outer conductor 3 to form a leaky coaxial cable, which is wound around the third drum 16. In addition, the method conventionally performed can be employ | adopted as the method of coat | covering the sheath 4. FIG.
In addition, the sheath material in a molten state is coated on the outer conductor 3 having the heat sealing layer 8 on the outer peripheral surface, so that the sheath material is superposed by the heat of extrusion of the sheath material (already fused by the heater of the former 14). By further heating the mating portion 7, the side edges 6 a and 6 a are more firmly adhered to each other, and the outer conductor 3 and the sheath 4 are formed by the heat fusion layer 8 on the entire outer peripheral surface of the outer conductor 3. Can be brought into close contact with each other.

  Therefore, the manufacturing method (wrap sheath forming method) of the present invention is configured to bend the copper tape 6 so that the insulator 2 is wound inside the flat copper tape 6 having the slot 5 (not corrugated). In this method, the side edges 6a and 6a are mutually overlapped in a circular tube shape, the side edges 6a and 6a are fixed (fused), and the sheath 4 is covered. Becomes a smooth straight type cable.

Next, another manufacturing method will be described with reference to FIG.
First, as in the case of FIG. 6, the insulator 2 is formed on the outer peripheral side of the inner conductor 1. The inner conductor 1 with the insulator 2 fitted thereon is wound around the first drum 12. The second drum 13 is wound with a copper tape 6 having a slot 5 penetrating in advance and a heat fusion layer 8 formed thereon.

Then, the insulator 2 having the internal conductor 1 inside is fed out from the first drum 12 and the copper tape 6 is fed out from the second drum 13, and both are continuously fed into the molding machine 17.
In the molding machine 17, the copper tape 6 is wound around the outer periphery of the insulator 2 while being formed into a circular tube. That is, as shown in the order of FIGS. 7A, 7B, and 7C, the insulator 2 is wound in a longitudinally wound manner so that both side edges 6a, 6a of the copper tape 6 overlap each other, and the external conductor 3 Form. Thereby, the overlapping portion 7 is linearly formed so as to be parallel to the cable axis C. At this time, the heat fusion layer 8 formed on the copper tape 6 is the outer peripheral side.

Further, in the molding machine 17, the outer peripheral conductor 3 is covered with a sheath material to form the sheath layer 4a, and the overlapping side edges 6a and 6a are thermally melted by the heat generated when the sheath layer 4a is formed. It is made to fuse with the adhesion layer 8.
That is, although not shown, the molding machine 17 includes a die for forming the copper tape 6 into a tubular shape, and a head for extruding and covering the sheath material on the outer peripheral side of the copper tape 6 that is formed into a tubular shape.

  The sheath material used as the sheath 4 is, for example, polyethylene resin. In the molding machine 17, the resin sheath material in a molten state is coated on the outer conductor 3, and the coated sheath material is cooled and solidified to form a sheath layer 4a (sheath 4). ). At the same time, the heat of the melted sheath material is conducted to the heat-sealing layer 8 to melt (melt) the solid heat-sealing layer 8 to give adhesiveness (adhesiveness), and to cool it. At the same time, the both side edges 6a and 6a of the copper tape 6 on which the inner peripheral heat fusion layer 8 is solidified and overlapped are fused (thermal fusion).

Further, according to this manufacturing method (wrap sheath forming method), the sheath material is formed in the heat sealing layer 8 formed on the entire outer peripheral surface of the outer conductor 3 by covering the outer conductor 3 with the sheath material in a molten state. With this heat, the solidifying sheath 4 and the outer conductor 3 can be brought into close contact with each other.
Then, the leaky coaxial cable obtained by forming the sheath 4 is wound around the third drum 16.
Similarly to the case of FIG. 6, the obtained leaky coaxial cable is not a corrugated cable but a straight type cable having a smooth outer peripheral surface.

  As described above, according to the present invention, the leakage including the inner conductor 1 and the circular outer conductor 3 provided on the outer peripheral side of the inner conductor 1 via the insulator 2 and having the slot 5 formed therein. In the coaxial cable, the outer conductor 3 is formed into a smooth circular tube by bending the copper tape 6 so that both side edges 6a, 6a of the copper tape 6 are overlapped, thereby forming a smooth circular tube. Since the edges 6a and 6a are fused to each other by a heat-sealing layer 8 formed on the copper tape 6, the dimensions, shape and pitch of the slot 5 are the slot punching dimensions, shape and pitch in the copper tape state. (Design dimensions) agree with each other without change, and the completed leaky coaxial cable can obtain the characteristics as designed. That is, the dimensional change / deformation of the slot 5 does not occur, and the shape can be stabilized.

Further, since the outer conductor 3 is held in a tubular shape by fusing with the heat fusing layer 8, a leaky coaxial cable having a stable shape for a long period of time, high durability, and reliability can be obtained.
In addition, since corrugation and slot punching after corrugation are not performed, the processing oil does not remain, the attenuation of the leaky coaxial cable does not deteriorate, and the desired VSWR characteristics and high frequency range ( 2GHz-5.3GHz) attenuation characteristics can be obtained.
Furthermore, since the outer conductor 3 is made of copper, it is possible to exhibit extremely good VSWR characteristics and attenuation characteristics.

Further, since the thickness T of the copper tape 6 is 0.05 mm to 0.2 mm (preferably 0.07 mm to 0.12 mm), the obtained leaky coaxial cable is not corrugated. , Sufficient flexibility can be provided. That is, the flexibility equivalent to that of the conventional corrugated leaky coaxial cable can be exhibited, and the cable can be bent with the same radius of curvature as the conventional one.
Further, since the slot 5 is formed on the outer peripheral wall portion of the outer conductor 3 on the opposite side of the overlapping portion 7 and the axis C, the overlapping portion 7 may affect the characteristics of the slot 5. Therefore, it is possible to exhibit good VSWR characteristics and attenuation characteristics.
In addition, a sheath 4 is provided on the outer peripheral side of the outer conductor 3, and the outer diameter D of the sheath 4 is set to 4 mm to 30 mm, so that the leaky coaxial cable can have sufficient flexibility. Can be bent with a radius of curvature similar to that of the cable, making cable laying easy.

Further, in the manufacturing method of the present invention, the insulator 2 is formed on the outer peripheral side of the inner conductor 1, the slot 5 is previously penetrated, and the heat sealing layer 8 is formed on the both side edges 6a, 6a. The insulating body 2 is wound in a side-by-side winding shape so as to overlap each other, the outer conductor 3 is formed, and the overlapped side edges 6a and 6a are fused by the heat sealing layer 8, and then the outer Since the outer conductor 3 is covered with the sheath 4 on the outer periphery of the conductor 3, the outer conductor 3 is formed in a smooth circular tube without corrugation, so the dimensions, shape, and pitch of the slot 5 are slot punched in a copper tape state. The dimensions, shape, and pitch (design dimensions) agree with each other without change, and the completed leaky coaxial cable can exhibit characteristics as designed.
By forming the slot 5 in the copper tape 6 in advance, it is not necessary to provide a slot forming machine in the cable production line, and a finished product can be obtained by a small number of processes, thereby reducing costs.

Further, in the present invention, both the side edges 6a and 6a are laminated on the copper tape 6 in which the insulator 2 is formed on the outer peripheral side of the inner conductor 1, the slot 5 is previously penetrated, and the heat-sealing layer 8 is formed. When the insulator layer 2 is formed, the insulator 2 is wound in a vertically attached winding shape so that the outer conductor 3 is formed, and the sheath material is coated on the outer periphery of the outer conductor 3 to form the sheath layer 4a. Since this is a method in which the overlapped side edge portions 6a, 6a are fused by the heat-sealing layer 8 by heat, the outer conductor 3 is formed in a smooth circular tube without corrugation, so that the slot 5 Since the dimensions, shape, and pitch coincide with each other without changing from the slot punching dimensions, shape, and pitch (design dimensions) in the copper tape state, the completed leaky coaxial cable can exhibit characteristics as designed.
By forming the slot 5 in the copper tape 6 in advance, it is not necessary to provide a slot forming machine in the cable production line, and a finished product can be obtained by a small number of processes, thereby reducing costs.
Furthermore, both the side edges 6a and 6a of the copper tape 6 can be fused simultaneously with the formation of the sheath layer 4a, so that the equipment can be omitted and the molding process can be shortened.

1 is a perspective view showing an embodiment of a leaky coaxial cable according to the present invention. It is a cross-sectional view of a leaky coaxial cable. It is an expanded sectional view of an overlap part. It is an expanded sectional view showing other examples of a superposition part. It is an expanded sectional view of a copper tape. It is a schematic whole figure of the manufacturing line explaining the manufacturing method of a leaky coaxial cable. It is sectional drawing explaining the manufacturing process of a leaky coaxial cable. It is a general | schematic general view of the manufacturing line explaining another manufacturing method. It is a perspective view of the conventional leaky coaxial cable. It is a schematic whole figure of the manufacturing line explaining the conventional manufacturing method. It is a top view of the metal tape explaining the problem by corrugation processing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner conductor 2 Insulator 3 Outer conductor 4 Sheath 4a Sheath layer 5 Slot 6 Copper tape 6a Side edge part 7 Overlay part 8 Thermal fusion layer C Axis axis D Outer diameter T Thickness

Claims (6)

  Leakage comprising an inner conductor (1) and a circular outer conductor (3) provided with an insulator (2) on the outer peripheral side of the inner conductor (1) and having a slot (5) formed In the coaxial cable, the outer conductor (3) is formed by bending the copper tape (6) so that both side edges (6a) and (6a) of the copper tape (6) are overlaid. The both side edges (6a) and (6a) which are formed into a smooth circular tube and are overlapped are bonded to each other by a heat-sealing layer (8) formed on the copper tape (6). Leaky coaxial cable characterized by   The leaky coaxial cable according to claim 1, wherein a thickness (T) of the copper tape (6) is 0.05 mm to 0.2 mm.   The leaky coaxial cable according to claim 1 or 2, wherein the slot (5) is formed in a peripheral wall portion on the opposite side of the outer conductor (3) with the overlapping portion (7) and the axis (C) interposed therebetween.   The leaky coaxial cable according to claim 1, 2 or 3, wherein a sheath (4) is provided on an outer peripheral side of the outer conductor (3), and an outer diameter (D) of the sheath (4) is 4 mm to 30 mm.   An insulator (2) is formed on the outer peripheral side of the inner conductor (1), a slot (5) is penetrated in advance, and a heat-sealing layer (8) is formed on both side edges (6a ) (6a) is wound in a vertical wrapping manner so as to overlap each other to form an outer conductor (3), and the both side edges (6a) (6a) are overlapped with the heat A method for producing a leaky coaxial cable, wherein the outer conductor (3) is covered with a sheath (4) after being fused with a fusion layer (8).   An insulator (2) is formed on the outer peripheral side of the inner conductor (1), a slot (5) is penetrated in advance, and a heat-sealing layer (8) is formed on both side edges (6a ) (6a) is wound so that the insulator (2) is vertically attached so as to overlap each other, the outer conductor (3) is formed, and the outer periphery of the outer conductor (3) is covered with a sheath material to form a sheath While the layer (4a) is being formed, the superimposed side edges (6a) and (6a) are fused by the heat-sealing layer (8) by heat at the time of forming the sheath layer (4a). A method for manufacturing a leaky coaxial cable.

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