JP6654739B2 - Leaky coaxial cable - Google Patents

Description

The present invention relates to leaky coaxial cables.
Priority is claimed on Japanese Patent Application No. 2017-176842 filed on September 14, 2017, the contents of which are incorporated herein by reference.

The leaky coaxial cable includes, for example, an inner conductor, an insulator covering the inner conductor, an outer conductor provided on the outer surface side of the insulator, and a sheath provided on the outer peripheral surface of the outer conductor. Has a structure formed as a radiating portion.
The electromagnetic wave signal supplied to the inner conductor is shielded by the outer conductor, but leaks to the outside through a slot, which is a radiation part. That is, the leaky coaxial cable is a cable-type antenna, and can be said to be a special elongated transmitting / receiving antenna. As the external conductor, for example, a metal tape is used (see Patent Document 1). The outer conductor is formed by vertically attaching a metal tape around the insulator.

Japanese Patent No. 5190147

  When manufacturing a leaky coaxial cable, if a metal tape is longitudinally attached in a state where a gap is formed between the insulator and the insulator, wrinkles are generated in the metal tape due to the extrusion pressure of the resin in the extrusion step of forming the sheath. Due to this, the characteristics as a leaky coaxial cable may vary in the length direction.

  The present invention has been made in view of the above circumstances, and provides a leaky coaxial cable that can prevent variations in characteristics.

A first aspect of the present invention is a leaky coaxial cable, in which an inner conductor extending in one direction, an insulator covering the inner conductor, and a metal tape having a slot formed are vertically attached to the insulator. And a non-metallic wire provided on the outer surface of the external conductor and containing a synthetic resin, and a sheath covering the external conductor and the non-metallic wire.
According to a second aspect of the present invention, in the leaky coaxial cable according to the first aspect, it is preferable that a conductor wire is further provided on an outer surface of the outer conductor.
According to a third aspect of the present invention, in the leaky coaxial cable according to the second aspect, at least one of the non-metallic wire and the conductor wire is preferably braided or horizontally wound.
A fourth aspect of the present invention is the leaky coaxial cable according to any one of the first to third aspects, wherein the slot has a rectangular shape and a first side along a width direction of the leaky coaxial cable. The length of the second side along the length direction of the leaky coaxial cable is longer than that of the leaky coaxial cable, and when the leaky coaxial cable is viewed in plan, the length of the first side of the slot is equal to the outer diameter of the outer conductor. On the other hand, it is preferably 60 to 90%.
According to a fifth aspect of the present invention, in the leaky coaxial cable according to the second aspect, at least a part of the conductor wire preferably forms a composite wire with the non-metallic wire.

  According to the aspect of the present invention, it is possible to suppress the generation of a gap between the insulator and the metal tape by using the non-metallic wire. Therefore, a variation in the structure in the length direction is reduced, and electrical characteristics such as impedance are stabilized. In addition, since a non-metallic wire is used, the radiation of the electromagnetic wave in the radiation part is not hindered.

(A) is a sectional view of the leaky coaxial cable of the first embodiment, and (B) is a plan view of the leaky coaxial cable of (A). (A) is sectional drawing of the leaky coaxial cable of a comparative form, (B) is a top view of (A) leaky coaxial cable. It is a figure showing an example of the relation between frequency and VSWR in leaky coaxial cable of a 1st embodiment and a comparative form. (A) is a sectional view of the leaky coaxial cable of the second embodiment, and (B) is a plan view of the leaky coaxial cable of (A). It is a figure showing the relation between frequency and VSWR in leaky coaxial cable of a 2nd embodiment and a comparative form. It is a figure showing the relation between the density of a conductor wire, and coupling loss. It is sectional drawing which shows the 1st modification of the leaky coaxial cable of 2nd Embodiment. It is sectional drawing which shows the 2nd modification of the leaky coaxial cable of 2nd Embodiment. It is a perspective view showing the structure of the 1st modification of a leaky coaxial cable of a 1st embodiment. It is a perspective view showing the structure of the 3rd modification of the leaky coaxial cable of a 2nd embodiment. It is a perspective view showing the structure of the 2nd modification of the leaky coaxial cable of a 1st embodiment. It is a perspective view showing the structure of the 3rd modification of the leaky coaxial cable of a 1st embodiment. It is a perspective view showing the structure of the 4th modification of the leaky coaxial cable of a 1st embodiment. It is a perspective view showing the structure of the 5th modification of a leaky coaxial cable of a 1st embodiment.

  Hereinafter, the leaky coaxial cable of the embodiment will be described with reference to the drawings.

1st Embodiment FIG. 1: (A) is sectional drawing of the leaky coaxial cable 10 of 1st Embodiment. FIG. 1A shows a cross section perpendicular to the direction of the central axis C (axial direction) of the internal conductor 1. FIG. 1B is a plan view of the leaky coaxial cable 10.
As shown in FIGS. 1A and 1B, a leaky coaxial cable 10 has an inner conductor 1, an insulator 2, an outer conductor 3, and a non-metallic wire from an inner peripheral side to an outer peripheral side. 4, a conductor wire 5, and a sheath 6.
The internal conductor 1 is a conductor such as a metal such as copper, for example, and is a linear body extending in one direction. The inner conductor 1 may be a stranded wire obtained by twisting a plurality of conductors.
The insulator 2 is provided so as to cover the outer peripheral surface of the internal conductor 1. For the insulator 2, an insulating resin such as foamed polyethylene is used.

The outer conductor 3 is a tape (for example, a metal tape) that is a conductor such as a metal (such as copper). The outer conductor 3 may be a metal foil such as a copper foil, for example. The thickness of the outer conductor 3 is, for example, 0.01 to 0.2 μm. 3a is an outer peripheral surface (outer surface) of the outer conductor 3.
The external conductor 3 may have a configuration in which a tape-shaped insulating base material (not shown) and an adhesive layer (not shown) are laminated.
As the insulating base material, a polyester resin such as polyethylene terephthalate (PET); a polyolefin resin such as polypropylene and polyethylene can be used. The insulating base material is formed on the inner peripheral surface side of the outer conductor 3. The adhesion layer is made of an ethylene ionomer resin (for example, Surlyn (registered trademark)). The adhesion layer is formed on the inner peripheral surface side of the insulating base material. The adhesion layer joins the outer conductor 3 and the insulating base material to the insulator 2. Slots need not be formed in the insulating base material and the adhesion layer.

  A plurality of slots 7 (radiating portions) as openings are formed in the outer conductor 3. The slots 7 are formed at intervals in the length direction. The slots 7 are preferably arranged in the length direction at a constant pitch. The pitch of the slots 7 is determined according to the frequency of the supplied high-frequency signal. The slot 7 can be formed, for example, by making a hole in a metal tape to be the outer conductor 3. The slot 7 can also be formed by pattern etching using a photolithography technique. The outer conductor 3 is wound around the insulator 2 so that the length direction of the metal tape is aligned with the length direction of the insulator 2 (that is, the outer conductor 3 is longitudinally attached).

In the leaky coaxial cable 10 shown in FIG. 1B, a rectangular slot 7 whose length direction (long side direction) extends along the length direction of the leaky coaxial cable 10 is formed in the outer conductor 3. The slot 7 has an opening formed such that one side L (long side L) in the length direction of the leaky coaxial cable 10 is longer than one side W (short side W) in the width direction of the leaky coaxial cable 10. . For example, when the leaky coaxial cable 10 is viewed in a plan view as shown in FIG. 1B, the length of the short side W of the slot 7 is about 60 to 90% of the outer diameter of the outer conductor 3. The length of the long side L of the slot 7 is about 2 to 10 times the short side W.
Regarding the shape and size of the slot, for example, in the case of a leaky coaxial cable for 2.4 GHz (the diameter of the outer conductor is 1.5 mm), the following slots can be used.
Slot shape: rectangular.
Slot width: 2 to 4 mm (varies according to the diameter of the cable and the width of the external conductor tape).
Slot length: 40 to 50 mm (45 to 55% of the slot pitch).
Slot pitch: 91 mm (changes according to the used frequency. For how to determine the pitch, see, for example, Japanese Patent Application Laid-Open No. 2013-229772).
As shown in FIG. 1B, when a rectangular slot 7 having a large opening size is formed along the length direction of the leaky coaxial cable 10, the outer conductor 3 near the slot 7 is separated from the insulator 2. It is easy to be in a floating state. Therefore, in the leaky coaxial cable 10 of the present embodiment, a non-metallic wire 4 described later is provided on the outer peripheral surface 3 a of the external conductor 3 to suppress the floating of the external conductor 3.

  The internal conductor 1 propagates a high-frequency signal supplied from an external signal source or the like. Since the high-frequency signal is shielded by the external conductor 3 in a portion where the slot 7 is not provided, no electromagnetic wave is radiated outside the leaky coaxial cable 10. At the location where the slot 7 exists, an electromagnetic wave is radiated to the outside of the leaky coaxial cable 10 through the slot 7.

The non-metallic wire 4 is a wire made of a non-metallic material. Examples of the nonmetallic material include synthetic resins such as nylon yarn (polyamide resin) and tetron yarn (polyester resin): natural materials such as cotton, silk, hemp, and wool: glass fibers. The non-metallic materials exemplified here are non-conductive materials. The non-metallic wire 4 is a non-conductive wire which is a non-conductive material. As the non-metallic wire 4, for example, a fiber of 10 to 1000 denier can be used. The non-metallic wire 4 may be composed of a single wire, or may be a stranded or non-twisted wire obtained by bundling a plurality of single wires.
When using a nylon thread as the non-metallic wire 4, for example, it is preferable to have the following characteristics.
Size (thickness): 420 ± 20d (denier).
Tensile strength: 2.2 kgf or more.
Elongation: 15% or more.
As described later, the step of providing the nylon yarn braid around the outer conductor (for example, a metal tape) is performed while applying a tension of 300 to 400 kgf to the nylon yarn. Therefore, the nylon yarn has sufficient resistance (tensile strength) to this tension.
Further, the non-metallic wire 4 also needs to have a sufficient elongation. When the elongation is large, the yarn has elasticity and the pressing force for pressing the outer conductor when braiding around the outer conductor is not too strong, so that wrinkles are not easily formed on the outer conductor. That is, since the deformation of the slot shape of the outer conductor can be suppressed, the characteristics of the leaky coaxial cable are stabilized. When a nylon yarn is used, the elongation of the nylon yarn is preferably 15% or more.

  The non-metallic wire 4 is braided or horizontally wound around the outer peripheral surface 3 a of the outer conductor 3, thereby pressing the outer conductor 3 against the insulator 2. Therefore, floating of the outer conductor 3 (gap between the insulator 2 and the outer conductor 3) can be suppressed, and the adhesion of the outer conductor 3 to the insulator 2 can be increased. Part of the non-metallic wire 4 is located at a position overlapping the slot 7.

The conductor wire 5 is a wire that is a conductor such as a metal. The metal forming the conductor wire 5 is, for example, copper, copper alloy, steel or the like. The conductor wire 5 is, for example, a tin-plated soft copper wire. The outer diameter of the conductor wire 5 is, for example, 0.05 to 0.5 mm. The conductor wire 5 may be made of a carbon-based material. Further, the conductor wire 5 may be composed of a single wire, or may be a stranded wire or a non-twisted wire obtained by bundling a plurality of single wires.
The conductor wire 5 is braided or horizontally wound around the outer peripheral surface 3 a of the outer conductor 3, thereby pressing the outer conductor 3 against the insulator 2. Therefore, the floating of the external conductor 3 can be suppressed, and the adhesion of the external conductor 3 to the insulator 2 can be increased.

  The sheath 6 has a resin such as polyvinyl chloride or flame-retardant polyethylene, and is provided so as to cover the outer conductor 3, the nonmetallic wire 4 and the conductor wire 5. The sheath 6 can be formed by extrusion molding.

The leaky coaxial cable 10 can be manufactured as follows.
An insulator 2 containing an internal conductor 1 is prepared. The tape-shaped external conductor 3 is vertically attached to the insulator 2 to enclose the insulator 2. Next, using a braiding machine or the like, the non-metallic wire 4 and the conductor wire 5 are provided on the outer peripheral surface 3a of the outer conductor 3 by braiding or horizontal winding. Here, a tension of 300 to 400 kgf is applied to the non-metallic wire 4 and the conductor wire 5. Therefore, the non-metallic wire 4 needs to have a sufficient tensile strength (for example, a tensile strength of 2.2 kgf or more) to withstand this.
Next, the sheath 6 is formed on the outer peripheral side of the outer conductor 3 by extrusion molding or the like. Thus, the leaky coaxial cable 10 shown in FIG. 1 and the like is obtained.

  In the leaky coaxial cable 10, by using the non-metallic wire 4, the floating of the outer conductor 3 can be suppressed, and the adhesion of the outer conductor 3 to the insulator 2 can be increased. Therefore, variation in the structure in the length direction is reduced, and electrical characteristics such as impedance are stabilized as described later. In the leaky coaxial cable 10, since the non-metallic wire 4 is used, the radiation of the electromagnetic wave in the slot 7 is not hindered.

Comparative Example FIGS. 2A and 2B show an example of a leaky coaxial cable as a comparative example. FIG. 2A is a cross-sectional view of the leaky coaxial cable 110 of the comparative embodiment. FIG. 2B is a plan view of the leaky coaxial cable 110. Note that the same components as those of the leaky coaxial cable 10 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

Leaky coaxial cable 110 has inner conductor 1, insulator 2, outer conductor 3, conductor wire 5, and sheath 6. In the leaky coaxial cable 110, unlike the leaky coaxial cable 10 of the first embodiment, a non-metallic wire is not used.
The conductor wire 5 is braided or horizontally wound around the outer peripheral surface 3 a of the outer conductor 3, thereby pressing the outer conductor 3 against the insulator 2.

FIG. 3 is a diagram illustrating an example of the relationship between the frequency and the VSWR in the leaky coaxial cable 10 of the first embodiment and the leaky coaxial cable 110 of the comparative embodiment.
In the example shown here, the leaky coaxial cable 10 of the first embodiment (see FIGS. 1A and 1B) includes an inner conductor 1 (outer diameter 0.6 mm) and an insulator 2 made of foamed polyethylene. (Outer diameter 1.6 mm), outer conductor 3 (thickness 0.01 mm), nonmetallic wire 4 of nylon (420 ± 20 denier), and conductor wire 5 of tinned annealed copper wire (outer diameter 0. 12 mm) and a sheath 6.
The non-metallic wire 4 is provided on the outer peripheral surface 3a of the outer conductor 3 by braiding (number of strokes: braid pitch: 17 mm).
The conductor wire 5 is provided on the outer peripheral surface 3 a of the outer conductor 3 by braiding (number of strokes: braid pitch: 17 mm).

  The leaky coaxial cable 110 of the comparative embodiment (see FIGS. 2A and 2B) includes an inner conductor 1 (outer diameter 0.6 mm), a foamed polyethylene insulator 2 (outer diameter 1.6 mm). , An outer conductor 3 (thickness 0.01 mm), a conductor wire 5 (outer diameter 0.12 mm) which is a tin-plated soft copper wire, and a sheath 6. The conductor wire 5 is provided on the outer peripheral surface 3 a of the outer conductor 3 by braiding (number of strokes: braid pitch: 17 mm).

  The VSWR is represented by the following equation using the reflection coefficient ρ.

  Usually, since the characteristic impedance of the cable is designed to a specific value, ρ is 0 and VSWR is 1 in an ideal state. However, in practice, there is a variation in the structure in the cable length direction, and an impedance mismatch occurs, so that a reflected wave is generated. Therefore, ρ is greater than 0 and VSWR is greater than 1. Therefore, the larger the VSWR, the greater the variation in the structure in the cable length direction.

  As shown in FIG. 3, the VSWR of the leaky coaxial cable 10 of the first embodiment is smaller than the VSWR of the leaky coaxial cable 110 of the comparative embodiment. From this, it can be seen that the use of the non-metallic wire 4 reduces the structural variation in the length direction of the leaky coaxial cable 10 and stabilizes electrical characteristics such as impedance.

Second Embodiment Next, a leaky coaxial cable 20 according to a second embodiment will be described. The description of the same components as those in the first embodiment will be omitted.
FIG. 4A is a cross-sectional view of the leaky coaxial cable 20 according to the second embodiment. FIG. 4B is a plan view of the leaky coaxial cable 20.
As shown in FIGS. 4A and 4B, the leaky coaxial cable 20 includes an inner conductor 1, an insulator 2, an outer conductor 3, and a non-metallic wire from the inner peripheral side to the outer peripheral side. 24 and a sheath 6.
The leaky coaxial cable 20 differs from the leaky coaxial cable 10 of the first embodiment (see FIGS. 1A and 1B) in that no conductor wire is used.

  The non-metallic wire 24 is a non-conductive wire made of a non-metallic material such as a synthetic resin, a natural material, and glass, like the non-metallic wire 4 in the first embodiment. The non-metallic wire 24 is braided or horizontally wound around the outer peripheral surface 3 a of the outer conductor 3, thereby pressing the outer conductor 3 against the insulator 2.

  In the leaky coaxial cable 20, the use of the non-metallic wire 24 can suppress the floating of the outer conductor 3 and increase the adhesion of the outer conductor 3 to the insulator 2. Therefore, a variation in the structure in the length direction is reduced, and electrical characteristics such as impedance are stabilized as described later. Further, in the leaky coaxial cable 20, since the non-metallic wire 24 is used, the radiation of the electromagnetic wave in the slot 7 is not hindered.

FIG. 5 is a diagram illustrating an example of the relationship between the frequency and the VSWR in the leaky coaxial cable 20 of the second embodiment and the leaky coaxial cable 110 of the comparative embodiment (see FIGS. 2A and 2B).
In the example shown here, the leaky coaxial cable 20 of the second embodiment (see FIGS. 4A and 4B) includes an inner conductor 1 (outer diameter 0.6 mm) and an insulator 2 made of foamed polyethylene. (Outer diameter: 1.6 mm), an outer conductor 3 (thickness: 0.06 mm), a nonmetallic wire 24 made of nylon (420 ± 20 denier), and a sheath 6. The non-metallic wire 24 is provided on the outer peripheral surface 3a of the outer conductor 3 by braiding (16 strokes, 17 mm braid pitch).

  As shown in FIG. 5, the VSWR of the leaky coaxial cable 20 of the second embodiment is smaller than the VSWR of the leaky coaxial cable 110 of the comparative embodiment (see FIGS. 2A and 2B). This indicates that the use of the non-metallic wire 24 reduces variations in the structure of the leaky coaxial cable 20 in the length direction, and stabilizes electrical characteristics such as impedance.

Next, a method of adjusting the amount of radio wave radiation leaking in the leaky coaxial cables 10 and 20 will be described. As means for adjusting the amount of radio waves leaking from the slot 7, two methods of (i) adjustment of the shape of the slot 7 and (ii) adjustment of the density (the number per conductor length) of the conductor wire 5 can be considered.
In the case of (i), a tool for forming the slot 7 in the metal tape to be the outer conductor 3 (for example, a tool for making a hole in the case of drilling, a mask pattern used for exposure in the case of a photoresist method) Need to be manufactured. In (i), there is a disadvantage that a cost is required when a design change is made, and a lead time is extended, so that it is not possible to quickly respond to an order.
In the case of (ii), the amount of leaked radio waves can be adjusted only by changing the type, density (the number of cables per cable length), etc. of the conductor wire 5, so that the cost can be reduced and the lead time can be reduced. The effect is small. Therefore, the method (ii) is useful as a method for adjusting the amount of radio wave radiation.

FIG. 6 is a diagram showing the relationship between the density of the conductor wires at 2.4 GHz and the coupling loss.
In FIG. 6, the density of the conductor wire is 0% when all the braids having 16 strokes are made of non-metallic wires as in the leaky coaxial cable 20 shown in FIGS. 4 (A) and 4 (B). . In other words, the structure is such that all the regions that are not braided by the conductor wire are covered with the non-metallic wire. The conductor wire density of 40% refers to a case where 40% of the number of strokes 16 is constituted by a conductor wire (tin-plated soft copper wire), and the remaining 60% is constituted by a non-metal wire (FIG. 1 (A) and FIG. 1 (B), see the leaky coaxial cable 10).
As shown in FIG. 6, as the ratio of the conductor wires increases, the coupling loss increases. Therefore, by adjusting the ratio of the conductor wires, it becomes possible to adjust the amount of radio wave radiation leaking.
When the non-metal wire is made of nylon yarn, the density of the conductive wire braid is 0 to 50%, so the braid density of the nylon yarn is in the range of 50 to 100%.

First Modification and Second Modification of Second Embodiment FIG. 7 is a sectional view showing a leaky coaxial cable 20A which is a first modification of the leaky coaxial cable 20 of the second embodiment. FIG. 8 is a sectional view showing a leaky coaxial cable 20B which is a second modification of the leaky coaxial cable 20 of the second embodiment. The same components as those described above are denoted by the same reference numerals, and description thereof will be omitted.

  As shown in FIG. 7, in the leaky coaxial cable 20A of the first modified example, the non-metallic wire 24A is a stranded wire obtained by twisting a plurality of nylon yarns or the like. Since the non-metallic wire 24A is a stranded wire, the strength is high. Therefore, even if tension is applied to the non-metallic wire 24A due to bending deformation of the leaking coaxial cable, disconnection of the non-metallic wire 24A can be suppressed. The inner conductor 1A is a stranded wire having a plurality of metal wires 1Aa. The inner conductor 1A is, for example, a stranded wire having seven metal wires 1Aa (soft copper wire (outer diameter 0.7 mm)).

  As shown in FIG. 8, in the leaky coaxial cable 20B of the second modification, the non-metallic wire 24B is a non-twisted wire having a plurality of untwisted nylon yarns and the like. In the leaky coaxial cable 20B, when the non-twisted wire is pressed against the outer conductor of the leaky coaxial cable 20B, the non-twisted wire spreads in the circumferential direction of the leaky coaxial cable, and the outer conductor can be pressed by the surface. Therefore, the floating of the external conductor 3 can be suppressed, and the adhesion of the external conductor 3 to the insulator 2 can be increased.

First Modification of First Embodiment FIG. 9 is a perspective view showing the structure of a leaky coaxial cable 10A which is a first modification of the leaky coaxial cable 10 of the first embodiment.
As shown in FIG. 9, the leaky coaxial cable 10A has an inner conductor 1A, an insulator 2, an outer conductor 3, a nonmetallic wire 4, a conductor wire 5, a sheath 6.
The outer conductor 3 is a copper foil having a thickness of 0.01 mm. On the outer conductor 3, an insulating base material 31 (thickness 0.01 mm) and an adhesion layer 32 (thickness 0.04 mm) are laminated.
The insulating substrate 31 is, for example, PET. The adhesion layer 32 is, for example, an ethylene ionomer resin (Surlyn (registered trademark)). The adhesion layer 32 is melted by the heat applied when the sheath 6 is formed, and joins the outer conductor 3 and the insulating base material 31 to the insulator 2.
The non-metallic wire 4 and the conductor wire 5 are provided on the outer peripheral surface 3a of the outer conductor 3 by braiding.

Third Modification of Second Embodiment FIG. 10 is a perspective view showing a structure of a leaky coaxial cable 20C which is a third modification of the leaky coaxial cable 20 of the second embodiment.
As shown in FIG. 10, the leaky coaxial cable 20 </ b> C has an inner conductor 1 </ b> A, an insulator 2, an outer conductor 3, a non-metallic wire 24, and a sheath 6 from the inner peripheral side to the outer peripheral side.
The non-metallic wire 24 is provided on the outer peripheral surface 3a of the outer conductor 3 by braiding.

Second Modification of First Embodiment FIG. 11 is a perspective view showing a structure of a leaky coaxial cable 10B which is a second modification of the leaky coaxial cable 10 of the first embodiment.
As shown in FIG. 11, the leaky coaxial cable 10B includes an inner conductor 1A, an insulator 2, an outer conductor 3, a non-metallic wire 4, a conductor wire 5, and a sheath from an inner peripheral side to an outer peripheral side. 6.
The non-metallic wire 4 and the conductor wire 5 are provided on the outer peripheral surface 3a of the outer conductor 3 by horizontal winding.

Third Modification of First Embodiment FIG. 12 is a perspective view showing the structure of a leaky coaxial cable 10C which is a third modification of the leaky coaxial cable 10 of the first embodiment.
As shown in FIG. 12, the leaky coaxial cable 10C has an inner conductor 1A, an insulator 2, an outer conductor 3, a non-metallic wire 4, a conductor wire 5, a sheath 6.
The non-metallic wire 4 is provided on the outer peripheral surface 3 a of the outer conductor 3 by a horizontal winding. The conductor wire 5 is provided on the outer peripheral surface 3a of the outer conductor 3 by braiding.

Fourth Modification of First Embodiment FIG. 13 is a perspective view showing a structure of a leaky coaxial cable 10D which is a fourth modification of the leaky coaxial cable 10 of the first embodiment.
As shown in FIG. 13, the leaky coaxial cable 10D includes an inner conductor 1A, an insulator 2, an outer conductor 3, a nonmetallic wire 4, a conductor wire 5, a sheath 6.
The non-metallic wire 4 is provided on the outer peripheral surface 3a of the outer conductor 3 by braiding. The conductor wire 5 is provided on the outer peripheral surface 3a of the outer conductor 3 by a horizontal winding.

Fifth Modification of First Embodiment FIG. 14 is a perspective view showing the structure of a leaky coaxial cable 10E which is a fifth modification of the leaky coaxial cable 10 of the first embodiment.
As shown in FIG. 14, the leaky coaxial cable 10E has an inner conductor 1A, an insulator 2, an outer conductor 3, a non-metallic wire 4, a composite wire 35, a sheath 6.
The composite wire 35 is a stranded wire or a non-twisted wire obtained by twisting a non-metal wire (nylon yarn) and a conductor wire (tin-plated soft copper wire). The composite wire 35 is provided on the outer peripheral surface 3a of the outer conductor 3 by braiding. Note that the composite wire 35 may be provided by a horizontal winding.

Although the preferred embodiments have been described above, these are merely examples of the present invention, and additions, omissions, substitutions, and other changes can be made without departing from the scope of the present invention.
The leaky coaxial cable may have a configuration in which at least one of the non-metallic wire and the conductor wire is braided or horizontally wound.

  DESCRIPTION OF SYMBOLS 1 ... Internal conductor, 2 ... Insulator, 3 ... External conductor, 3a ... Outer peripheral surface (outer surface), 4, 24 ... Non-metallic wire, 5 ... Conductor wire, 6 ... ··· Sheath, 7: slot, 10, 10A, 10B, 10C, 10D, 10E, 20, 20A, 20B, 20C: leaky coaxial cable, 35: composite wire.

Claims (6)

An inner conductor extending in one direction;
An insulator covering the inner conductor;
An external conductor provided with a metal tape having a slot formed longitudinally attached to the insulator,
A non-metallic wire provided on the outer surface of the outer conductor and including a synthetic resin,
A sheath covering the outer conductor and the non-metallic wire,
The non-metallic wire consists only of the nylon yarn, untwisted wire der the bundled plurality of the single line is, presses the outer conductor in the form of spread in the circumferential direction of the insulator, leakage coaxial cable.   The leaky coaxial cable according to claim 1, further comprising a conductor wire on an outer surface of the outer conductor. The leaky coaxial cable according to claim 2 , wherein at least one of the non-metallic wire and the conductor wire is braided or horizontally wound. The non-metallic wire and the conductor wire are provided by braiding,
The braid density of the conductor wire is 0 to 50%,
The leaky coaxial cable according to claim 2 or 3 , wherein the density of the braid of the non-metallic wire is 50 to 100%. The slot is
Rectangular shape,
The second side along the length direction of the leaky coaxial cable is longer than the first side along the width direction of the leaky coaxial cable,
The length of the first side of the slot is 60 to 90% with respect to the outer diameter of the outer conductor when the leaky coaxial cable is viewed in plan, according to any one of claims 1 to 4. A leaky coaxial cable as described. The leaky coaxial cable according to any one of claims 2 to 4 , wherein at least a part of the conductor wire forms a composite wire with the non-metallic wire.

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