JP2020113363A - Coaxial cable excellent in flexible phase stability - Google Patents

Abstract

To provide a coaxial cable which prevents characteristics from being lowered even when being bent and is excellent in flexible phase stability.SOLUTION: A coaxial cable 10 includes a center conductor 11, an insulator 12 provided on an outer periphery of the center conductor 11, a first external conductor 13a which is composed of a first metal resin tape that is longitudinally attached to an outer periphery of the insulator 12, a second external conductor 13b which is composed of a thin metallic wire provided on an outer periphery on the first exterior conductor 13a so as to laterally wound around the outer periphery thereof, a third external conductor 13c which is composed of a metal resin tape provided on an outer periphery of the second exterior conductor 13b so as to laterally wound around the outer periphery thereof, and an externally-covering body 14 which is obtained by bonding a resin tape provided so as to laterally wound around the outer periphery of the third external conductor 13c through a fusion layer to the third external conductor 13c.SELECTED DRAWING: Figure 1

Description

The present invention relates to a coaxial cable, and more particularly, to a coaxial cable having excellent bending phase stability in which characteristics are not easily deteriorated even when bent or returned.

Coaxial cables are used for transmission of high-frequency signals because they have excellent shielding characteristics against noise and the like. Such a coaxial cable has a problem that, when an external force is applied to the cable, the insulator is deformed, the impedance is changed, and reflection attenuation occurs, so that the transmission efficiency is reduced. Further, when the coaxial cable is bent or returned, there is a problem that the insulator and the outer conductor layer are displaced from each other in the axial direction, resulting in phase fluctuation and noise.

In order to solve such a problem, Patent Document 1 proposes a coaxial cable that can be returned to the phase before the cable bending process even if the cable bending process is performed after the cable bending process is performed. In this coaxial cable, the second outer conductor layer has a braid structure with a braid angle of 50 degrees or more, and the first outer conductor layer is pressed by the second outer conductor layer at a small pitch. When the bending process is performed, wrinkles and buoyancy do not occur in the first outer conductor layer, and no air layer is formed between the first outer conductor layer and the dielectric layer. As a result, even if the cable is bent back thereafter, wrinkles and buoyancy do not occur in the first outer conductor layer, and an air layer does not occur between the first outer conductor layer and the dielectric layer. It is thought that it is possible to return to the phase before bending.

JP, 2011-198488, A

In recent years, coaxial cables have been used to transmit high-frequency signals in electronic devices such as personal computers, smartphones, and tablet terminals, which are becoming smaller, and in order to realize wiring within the device in a narrow space, It is required to reduce the diameter. The reduction in diameter is realized by thinning each of the constituent layers.

However, when the configuration of the coaxial cable proposed in Patent Document 1, for example, is applied to the reduced-diameter coaxial cable, since the second outer conductor layer has a braided structure, when the coaxial cable is bent or returned during wiring, The twists peculiar to the braided structure tended to cause wrinkles in the thin metal foil vertically attached, and the wrinkles tended to increase the bending phase. It is said that the braided structure is tightly tightened and strongly restrains the metal foil vertically attached to suppress the generation of wrinkles.However, the coaxial cable with the thin metal foil biting into the twist present in the thick braided structure It was considered that the presence of the twists rather caused the wrinkles when the was bent or returned.

An object of the present invention is to provide a coaxial cable which is excellent in bending phase stability and whose characteristics are less likely to deteriorate even when bent or returned.

A coaxial cable according to the present invention includes a center conductor, an insulator provided on the outer periphery of the center conductor, a first outer conductor formed of a first metal resin tape vertically attached to the outer periphery of the insulator, and the first outer conductor. A second outer conductor made of a thin metal wire wound laterally around the outer conductor, a third outer conductor made of a second metal resin tape wound laterally around the outer circumference of the second outer conductor, and 3. A resin tape, which is wound around the outer periphery of the third outer conductor, is adhered to the third outer conductor via a fusion layer.

According to the present invention, the second outer conductor is not a braided structure having a twist, but a thin metal wire wound horizontally, so that the metal layer of the first outer conductor is caused by the twist in the braided structure. It is possible to prevent wrinkles from occurring in the skin. Further, a thin metal wire (second outer conductor) is sandwiched between a first outer conductor vertically attached with a first metal resin tape and a third outer conductor horizontally wound with a second metal resin tape. Since there is a jacket that adheres the resin tape that covers the outer conductor by winding it through the fusing layer, even if the outer conductor is bent or unbent due to the integral structural form, lateral displacement occurs in each outer conductor. Hateful. As a result, a gap or void is not formed in each outer conductor, and a coaxial cable having excellent bending phase stability in which characteristics are not easily deteriorated even when bent can be obtained.

In the coaxial cable according to the present invention, the first outer conductor is vertically attached to the outer circumference of the insulator so as to partially overlap with each other with a width within a range of 0.1 to 3 mm.

In the coaxial cable according to the present invention, the second outer conductor is horizontally wound at a pitch within a range of 10 to 20 mm.

In the coaxial cable according to the present invention, the third outer conductor is horizontally wound with a lap of 1/5 to 1/2 at a horizontal winding pitch of 1.5 to 5 mm.

In the coaxial cable according to the present invention, the jacket is horizontally wound with a lap of 1/5 to 1/2 at a horizontal pitch of 1.5 to 5 mm.

In the coaxial cable according to the present invention, the bending phase obtained by bending the 700 mm long coaxial cable so as to form a circle having a radius of curvature of 50 mm and performing a network analysis at a frequency of 26.5 GHz is 8 (deg). It is as follows.

According to the present invention, it is possible to provide a coaxial cable which is excellent in bending phase stability and whose characteristics are not easily deteriorated even when bent or returned.

It is a perspective block diagram which shows an example of the coaxial cable which concerns on this invention. It is explanatory drawing which shows the measurement form of a bending phase.

An embodiment of a coaxial cable according to the present invention will be described with reference to the drawings. The present invention includes inventions having the same technical idea as the embodiments described below and the embodiments described in the drawings, and the technical scope of the present invention is limited only to the description of the embodiments and the description of the drawings. Not something.

[coaxial cable]
As shown in FIG. 1, a coaxial cable 10 according to the present invention includes a center conductor 11, an insulator 12 provided on the outer periphery of the center conductor 11, and a first metal resin tape vertically attached to the outer periphery of the insulator 12. A first outer conductor 13a, a second outer conductor 13b made of thin metal wire wound around the outer circumference of the first outer conductor 13a, and a metal resin tape wound around the outer circumference of the second outer conductor 13b. A third outer conductor 13c consisting of and a jacket 14 formed by bonding a resin tape, which is wound around the outer periphery of the third outer conductor 13c, to the third outer conductor 13c via a fusion layer. There is.

In this coaxial cable 10, the second outer conductor 13b is not a braid with twists but a thin metal wire wound horizontally. Therefore, the second outer conductor 13b is the first outer conductor 13a due to the twists in the braided structure. It is possible to prevent the thin metal layer from wrinkling. Furthermore, a thin metal wire (second outer conductor 13b) is sandwiched between a first outer conductor 13a vertically attached with a first metal resin tape and a third outer conductor 13c horizontally wound with a second metal resin tape. Since it has the resin tape that covers the third outer conductor 13 by winding it horizontally as the outer cover body 14 that is adhered via the fusion layer, even if bending or unbending is performed by these integral structural forms, The lateral displacement does not easily occur in each outer conductor. As a result, it is possible to obtain the coaxial cable 10 having excellent bending phase stability, in which no gaps or voids are formed in each outer conductor and the characteristics are not easily deteriorated even when bent.

Hereinafter, each component will be described in detail.

<Coaxial cable>
As shown in FIG. 1, the coaxial cable 10 includes a center conductor 11, an insulator 12 continuously provided on the outer periphery of the center conductor 11 in the longitudinal direction, and an outer conductor 13 provided on the outer periphery of the insulator 12. (13a to 13c) and a jacket 14 provided on the outer periphery of the outer conductor 13. The outer conductor 13 includes a first outer conductor 13a, a second outer conductor 13b, and a third outer conductor 13c.

(Center conductor)
The center conductor 11 is composed of one element wire extending in the longitudinal direction of the coaxial cable 10, or is formed by twisting a plurality of element wires. The type of wire is not particularly limited as long as it is a good conductive metal, but a good conductive metal conductor such as copper wire, copper alloy wire, aluminum wire, aluminum alloy wire, copper-aluminum composite wire, or the surface thereof. Those having a plating layer applied thereto can be preferably mentioned. From the viewpoint of high frequencies, copper wires and copper alloy wires are particularly preferable. As the plating layer, a solder plating layer, a tin plating layer, a gold plating layer, a silver plating layer, a nickel plating layer and the like are preferable. The cross-sectional shape of the strand is not particularly limited, either, but the wire may have a circular or substantially circular cross-sectional shape, or may have a rectangular shape.

The cross-sectional shape of the central conductor 11 is also not particularly limited, but may be circular (including oval), rectangular, or the like. The outer diameter of the center conductor 11 is desired to be as large as possible so that the electric resistance (AC resistance, conductor resistance) is small. However, in order to reduce the final outer diameter of the coaxial cable, for example, 0.09 is set. It may be in the range of about 1 mm. An insulating film (not shown) may be provided on the surface of the central conductor 11 as necessary. The type and thickness of the insulating film are not particularly limited, but those that decompose well during soldering are preferable, and thermosetting polyurethane film and the like can be preferably mentioned.

(Insulator)
The insulator 12 is an insulating layer having a low dielectric constant that is continuously provided on the outer periphery of the center conductor 11 in the longitudinal direction. The material of the insulator 12 is not particularly limited and is arbitrarily selected according to the required impedance characteristics, but a low dielectric constant fluorine resin such as PFA, ETFE, or FEP is preferable. The material of the insulator 12 may contain a colorant. The thickness of the insulator 12 is not particularly limited and is arbitrarily selected according to the required impedance characteristics, but it is preferably within a range of, for example, about 0.15 to 1.5 mm. The method of forming such an insulator 12 is not particularly limited, and examples thereof include extrusion and coating. The structure of the insulator 12 may be a solid structure, a hollow structure, or a foamed structure. Since the hollow structure and the foamed structure have voids inside the structure, the dielectric constant can be further reduced. The hollow structure can be exemplified by a cross-sectional form in which the void is surrounded by the inner annular portion, the outer annular portion, and the connecting portion.

(Outer conductor)
The outer conductor 13 is provided on the outer circumference or the outer circumference of the insulator 12. The outer conductor 13 includes a first outer conductor 13a in which a first metal resin tape having a metal layer surface facing outward is vertically attached on an insulator 12, and a thin metal wire is wound horizontally on the first outer conductor 13a. And a third outer conductor 13c formed by horizontally winding a second metal resin tape having a metal layer surface inside on the second outer conductor 13b. .. The outer conductor 13 having such a triple structure has a large conductor cross-sectional area and can reduce insertion loss. In the present application, the reference numeral 13a is also used for the first metal resin tape forming the first outer conductor 13a, the reference numeral 13b is used for the metal thin wire forming the second outer conductor 13b, and the third outer conductor 13c is used. The reference numeral 13c may also be used for the second metal resin tape constituting the tape.

The first outer conductor 13a is formed by vertically attaching a first metal resin tape on the insulator 12 (also referred to as the periphery of the insulator 12). The vertical attachment is performed with the metal layer surface forming the first metal resin tape facing outward (to the side of the second outer conductor 13b provided thereafter). The first metal resin tape has a metal layer provided on a resin base material. The resin substrate is not particularly limited, but a polyester film such as polyethylene terephthalate or polyethylene naphthalate can be preferably used. The thickness of the resin base material is arbitrarily selected, for example, within the range of about 2 to 20 μm. Preferred examples of the metal layer include a copper layer and an aluminum layer. Preferable examples of the metal layer include a film formed by vapor deposition or plating on a resin base material, a metal foil bonded via an adhesive layer (for example, a polyester-based thermoplastic adhesive resin, etc.), and the like. The thickness of the metal layer is not particularly limited and varies depending on the forming means, but the thickness of the metal layer formed by vapor deposition or plating can be arbitrarily selected within the range of about 2 to 8 μm, and the metal foil is laminated. Can be arbitrarily selected from the range of about 6 to 16 μm. Even with such a thin metal layer thickness, the second outer conductor 13b provided on the second outer conductor 13b is a thin metal wire wound in a horizontal direction, does not have a twist like a braided structure, and further has a third outer layer. Since the conductors 13c are bonded via the fusion layer, it is possible to prevent wrinkles from being formed in the metal layer or the metal foil even when the coaxial cable 10 is bent or bent back. The total thickness of the first metal resin tape is preferably within the range of about 0.004 to 0.036 mm.

As shown in FIG. 1, the vertical attachment is such that the resin base material side of the first metal resin tape is the insulator 12 side and the metal layer surface side is the outer side (the second outer conductor side) in the longitudinal direction so as to partially overlap. It is wrapped so that it wraps together. The width of the first metal resin tape is not particularly limited, but is set by the outer peripheral length of the insulator 12 and the size (width) of the overlapping portion. Partially overlapping means overlapping along the longitudinal direction with a width within the range of 0.1 to 3 μm. By vertically arranging them so as to partially overlap with each other, when the third outer conductor 13c is bonded via the fusion bonding layer, even if the coaxial cable 10 is bent or bent back, a break or a gap in the metal layer occurs. Can be prevented.

A second outer conductor 13b is provided on the first outer conductor 13a, and a third outer conductor 13c is further provided on the second outer conductor 13b. By doing so, the first outer conductor 13a is pressed by the second outer conductor 13b and the third outer conductor 13c, and even when the coaxial cable 10 is bent or bent back, the thin metal wire of the second outer conductor 13b is pressed. It is possible to prevent the creases from forming a gap between the lines, and it is possible to prevent the creases and wrinkles due to the gaps between the lines from occurring in the metal layer or the metal foil of the first outer conductor 13a. As a result, even if bent or unbent, the distance between the outer conductor 13 (13a, 13b, 13c) and the central conductor 11 does not change, so phase fluctuations are less likely to occur, and signal transmission characteristics (attenuation amount, skew) are reduced. Can be suppressed. In particular, even when a differential signal is transmitted at a high speed, it is possible to prevent the signal transmission speed from changing between two lines and prevent the transmission characteristic from deteriorating. Further, due to such an outer conductor structure, the change of the dielectric constant does not occur even when the bending stress is repeatedly applied.

The second outer conductor 13b is formed by horizontally winding a thin metal wire on the first outer conductor 13a. The thin metal wire is not particularly limited as long as it is a fine conductive metal wire that can be provided as the second outer conductor 13b of the coaxial cable 10 on the outer periphery of the first outer conductor 13a (longitudinal attachment of the first metal resin tape). For example, various thin metal wires represented by tin-plated copper wires can be preferably used. The diameter of the thin metal wire is not particularly limited, but may be, for example, within the range of about 0.04 to 0.1 mm. The number of the thin metal wires is arbitrarily selected according to the outer diameter of the first outer conductor 13a, the outer diameter of the coaxial cable 10 to be planned, and the like, and about 32 to 77 wires are provided on the first outer conductor 13a, as in Examples described later. The thin metal wire can be wound horizontally to form the second outer conductor 13b.

The horizontal winding pitch at the time of horizontally winding the metal thin wire is not particularly limited, but may be a pitch within a range of 10 to 20 mm, for example. Since the metal thin wire wound in this manner has no twist like the braided structure, even if it is bent or bent back, there is no metal layer that cuts into the twist. Therefore, the wrinkles caused by the movement of the twist caused by bending do not occur. In addition, the horizontal winding of the thin metal wire reduces the thickness of the second outer conductor 13b to the extent that the same effect (sealing effect, etc.) is produced as compared with the braided structure in which the thin wires intersect to form a twist. This is advantageous from the viewpoint of reducing the diameter of the coaxial cable 10.

The third outer conductor 13c is formed by horizontally winding a second metal resin tape on the second outer conductor 13b. The second metal resin tape has a metal layer provided on a resin base material, and may be the same as or different from the first metal resin tape used in the first outer conductor 13a. Good. The material, thickness and the like of the resin base material and the metal layer can be arbitrarily selected and used from those described in the description of the first metal resin tape. The total thickness of the second metal resin tape is preferably in the range of 0.004 to 0.036 mm.

The second metal resin tape is horizontally wound at a horizontal winding pitch within a range of 1.5 to 10 mm. When horizontally winding at this horizontal winding pitch, the tape width is selected so that the wrap becomes 1/5 to 1/2. It is preferable to arbitrarily select and use the horizontal winding pitch and the width of the tape for horizontal winding with the wrap. The horizontal winding of the second metal resin tape is preferably performed in a state in which the metal layer side faces the metal thin wire so that the metal layer directly contacts the metal thin wire of the second outer conductor 13b. As a result, the metal thin wire and the metal layer can be electrically conducted, and since the metal thin wire is also in direct contact with the metal layer of the first metal resin tape, the electrical conduction can be further stabilized. It is possible to secure a stable shield characteristic. By directly arranging the metal layers on the thin metal wires in direct contact with each other without causing a gap between the metal layers of the second metal resin tape by arranging the metal layers of the second metal resin tape so as to face each other under the horizontal winding pitch and the wrap. You can As a result, even if the thin metal wire, which exhibits flexibility during bending such as bending or unbending, is displaced to some extent, electrical conduction can be further stabilized, and stable shield characteristics can be secured.

The horizontal winding pitch of the second metal resin tape is preferably within the range of 1/5 to 1/2 of the horizontal winding pitch of the metal thin wire. By doing so, the second metal resin tape can be wound without a gap and the metal thin wire can be pressed. The horizontal winding direction of the second metal resin tape may be the same winding direction as the horizontal winding direction of the above-described thin metal wire, or the reverse winding direction, but the reverse winding direction is preferable. The tape width is arbitrarily selected according to the winding pitch, the easiness of winding, and the like, and can be set within the range of, for example, 3 to 10 mm.

The second metal resin tape is bonded to the outer cover body 14 made of a resin tape with a fusion bonding layer, which will be described later, via the fusion bonding layer. As a result, the thin metal wire (second outer conductor 13b) located under the second metal resin tape does not come apart during the terminal strip. With such a mode, wrinkles and buoyancy do not occur in the metal layer that constitutes the first outer conductor 13a, and phase fluctuations do not easily occur even when the coaxial cable is bent or bent back, and the characteristics are stable. As a result, the bending phase stability is excellent.

The total thickness of the first outer conductor 13a, the second outer conductor 13b, and the third outer conductor 13c that form the outer conductor 13 having a triple structure is the wire diameter and the number of twists of the thin metal wire to be used, the first metal resin tape, and There is no particular limitation because it depends on the thickness of the metal layer of the second metal resin tape, the thickness of the resin base material, and the like. With such a structural form of the outer conductor 13, a stable outer conductor structure can be provided, and flexibility is improved and stress concentration can be improved, as compared with the conventional outer conductor having a vertical mounting structure or a horizontal winding structure of a metal tape. It's hard to get up and it's hard to break.

(Coat)
The outer jacket 14 is provided on the outer periphery of the outer conductor 13, and can be fastened to the third outer conductor 13c to tighten the second outer conductor 13b (horizontal winding of fine metal wire). The outer casing 14 is formed by horizontally winding the resin tape with an insulating fusion layer with the fusion layer side facing the third outer conductor 13c. Examples of the material of the resin tape constituting the outer cover 14 include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (PA), polyimide (PI), polyphenylene sulfide (PPS), ethylene tetrafluoride. Ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), fluorinated resin copolymer (perfluoroalkoxy fluororesin: PFA), polyether ether ketone (PEEK), and the like. be able to. In terms of hardness and elongation, polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and the like are preferable. These resin tapes usually have a single layer, but may have two or more layers depending on the purpose. The thickness of the resin tape is not particularly limited as long as it can ensure the necessary withstand voltage, but may be in the range of about 0.004 to 0.01 mm. The resin tape may be colored. The coloring can be provided by containing a colorant in the resin tape, or applying or printing the colorant on the resin tape. By coloring the resin tape, different colors can be given to the obtained coaxial cables 10, and the colors can identify the coaxial cables 10 having individual roles.

The fusion layer is provided on one side of the resin tape. The material of the fusing layer is a resin composition mainly composed of a thermoplastic resin, and it is preferable that the fusing layer has a property that a cross-linking reaction takes place at a specific temperature or higher to allow adhesion. By having such a property, the resin tape with the fusion layer is provided by winding the fusion layer sideways with the fusion layer on the side of the third outer conductor 13c, and at that time or thereafter, it is heated to a certain temperature or higher to cause a crosslinking reaction. And bond it to the outer conductor 13. By doing so, the resin tape with a fusion bonding layer adheres and fixes the second metal resin tape 13c located thereunder via the fusion bonding layer, so that the displacement of the metal layers forming the second metal resin tape is prevented. Can be prevented. As a result, it is possible to maintain stable shield characteristics even when bending occurs, and the thin metal wires (second outer conductor 13b) located below the second metal resin tape 13c are separated during terminal stripping. Can be suppressed.

Examples of the material of the fusion bonding layer include thermosetting resins such as polyurethane resin, polyester resin, and polyesterimide resin. Of these, polyurethane resins and polyester resins are preferable. The resin composition for forming a fusion layer that forms the fusion layer contains a crosslinking agent and a solvent. Moreover, various additives are included as needed. Those crosslinking agents, solvents and additives are not particularly limited, and various crosslinking agents, solvents and additives depending on the kind of polyurethane resin, polyester resin, polyesterimide resin and the required properties thereof are used as necessary. .. The thickness of the fusion layer is also not particularly limited, but can be about 0.001 mm. The total thickness of the outer jacket 14 is preferably within the range of about 0.025 to 0.1 mm.

The horizontal winding pitch at the time of horizontally winding the resin tape with the fusion bonding layer is preferably the same as or substantially the same as the horizontal winding pitch of the second metal resin tape 13c. By setting the wrap and the horizontal winding pitch of the resin tape with the fusion-bonding layer and the horizontal winding pitch of the second metal resin tape 13c as described above, it is possible to secure the overlap of the resin tapes fixed by the fusion-bonding layer. The resin tape can be wound in a horizontal direction at a pitch such that the metal layer arranged therebelow is less likely to be displaced. Therefore, even when the thin metal wire 13b is bent and slightly displaced, the second metal resin tape 13c that covers the thin metal wire 13b and the resin tape adhered thereon can maintain stable contact. Has been done. As a result, stable shield characteristics can be maintained.

The horizontal winding direction of the resin tape with a fusion bonding layer may be the same winding direction as the horizontal winding direction of the above-mentioned second metal resin tape 13c or the opposite winding direction, but it may be wound in the opposite direction. preferable.

The final outer diameter of the obtained coaxial cable 10 is preferably within the range of about 0.6 to 3.5 mm. Such a coaxial cable 10 can prevent wrinkles from being generated in the metal layer of the first outer conductor 13a. In addition, due to the integral structure, lateral displacement is unlikely to occur in each of the outer conductors 13a to 13c even if bending or unbending is performed. As a result, a gap or void is not formed in each outer conductor, and a coaxial cable having excellent bending phase stability in which characteristics are not easily deteriorated even when bent can be obtained.

(Bending phase)
The bending phase can be obtained by bending the coaxial cable 10 having a length of 700 mm to form a circle having a radius of curvature of 50 mm and performing a network analysis at a frequency of 26.5 GHz. FIG. 2 is an explanatory diagram showing an example of the measurement system body. The bending phase obtained by this measurement is preferably 8 (deg) or less. In FIG. 2, reference numeral 20 is a bending phase measuring method, reference numeral 21 is a network analyzer, reference numeral 22 is a measuring cable, reference numeral 23 is a coaxial cable to be measured, and reference numeral 24 is a measuring cable and a coaxial cable to be measured. It is a connector with a cable.

Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the examples below.

[Example 1]
First, the coaxial cable 10 shown in FIG. 1 was produced. As the central conductor 11, a silver-plated annealed copper wire having a diameter of 0.203 mm was used. Next, a 0.21 mm thick PFA resin (made by DuPont) layer was extruded on the outer periphery of the center conductor 11 to have an outer diameter of 0.623 mm. Next, the triple-layered outer conductor 13 including the first outer conductor 13a, the second outer conductor 13b, and the third outer conductor 13c was formed. As the first outer conductor 13a, a first metal resin tape having a width of 2.5 mm and a total thickness of 0.02 mm in which a 0.008 mm-thick PET base material is provided with a 0.008 mm-thick copper foil is used. The copper foil side was placed outside (the side of the second outer conductor 13b provided thereafter) so as to overlap vertically with a width of 0.631 mm. The second outer conductor 13b is formed by using 38 tin-plated annealed copper wires (thin metal wires; abbreviated as TCW) having a diameter of 0.05 mm, and left-handed with a pitch of 14 mm to form an outer diameter after forming the second outer conductor 13b. It was 0.763 mm. Next, the third outer conductor 13c is a second metal resin tape having a width of 3 mm and a total thickness of 0.02 mm in which a 0.008 mm-thick PET base material is provided with a 0.008 mm-thick copper foil. The copper foil was wound rightward so that the copper foil side was the second outer conductor 13b side and a 1/2 wrap was formed at a pitch of 4 mm. The outer diameter after providing the outer conductor 13 having a triple structure was 0.8 mm. Then, a PET tape (resin tape) having a thickness of 0.04 mm and a width of 3 mm with a fusion layer is used as the jacket 14, and the fusion layer side is the second metal resin tape side, and the second metal resin tape is used. It was left-handed, which is the opposite of the winding direction. The horizontal winding pitch at that time was 2 mm and was 1/2 lap. The outer diameter of the coaxial cable 10 was 0.85 mm.

[Example 2]
In Example 1, the diameter of the central conductor 11 was changed to 0.287 mm, the number of metal thin wires in the second outer conductor 13b was changed to 55, and the outer diameter after forming the second outer conductor 13b was changed to 1.01 mm. Then, the pitch of the third outer conductor 13c was changed to 1/3 lap with a pitch of 4 mm. Other than that was carried out similarly to Example 1, and produced the coaxial cable of Example 2 which has an outer diameter of 1.12 mm.

[Example 3]
In Example 1, the insulator 12 was changed to a hollow structure having a thickness of 0.21 mm, the number of metal thin wires in the second outer conductor 13b was 35, and the outer diameter after forming the second outer conductor 13b was 0. .66 mm, and the third outer conductor 13c is a 0.004 mm thick PET base material on which a 0.008 mm thick copper foil is provided. The second metallic resin has a width of 3 mm and a total thickness of 0.02 mm. The tape is changed to 1/2 wrap at a pitch of 1.9 mm, and a PET tape (resin tape) with a fusion layer of 0.025 mm in thickness and 3 mm in width is used as the outer cover 14 and a horizontal winding pitch is 1.5 mm. It was 1/2 lap. In addition, the insulator 12 having a hollow structure is formed by extruding a PFA resin (manufactured by DuPont) at 350° C. with a die nipple for forming a hollow structure to form an inner ring portion having a thickness of 0.05 mm. A hollow structure having a cross-sectional shape surrounded by an outer annular portion having a thickness of 0.05 mm and a connecting portion having a thickness of 0.05 mm is molded, and the porosity is 54%. Other than that was carried out similarly to Example 1, and produced the coaxial cable of Example 3 which has an outer diameter of 0.76 mm.

[Example 4]
In Example 1, the center conductor 11 was changed to seven silver-plated annealed copper wires having a diameter of 0.127 mm with an outer diameter of 0.381 mm twisted at a pitch of 5 mm, and the thickness of the insulator was changed to 0.380 mm. , The number of fine metal wires in the second outer conductor 13b is 44, and the outer diameter after forming the second outer conductor 13b is changed to 1.32 mm, and the third outer conductor 13c is a PET substrate having a thickness of 0.004 mm. Using a second metal resin tape with a width of 3.5 mm and a total thickness of 0.02 mm provided with a copper foil with a thickness of 0.008 mm on top, change to 1/3 wrap at a pitch of 4.0 mm, A PET tape (resin tape) with a fusion layer having a thickness of 0.05 mm and a width of 3.5 mm was used as the body 14 and was lapped at a horizontal pitch of 4 mm to ⅓ lap. Other than that was carried out similarly to Example 1, and produced the coaxial cable of Example 4 which has an outer diameter of 1.40 mm.

[Comparative Example 1]
In Example 1, the center conductor 11 and the first outer conductor 13a were the same, and the metal thin wire braid was provided on the first outer conductor 13a. The metal fine wire braid was braided with the number of tinned annealed copper wires (metal fine wires) having a diameter of 0.05 mm, the number of which was 4, the number of strokes was 16 and the pitch was 6 mm, and the outer diameter was 0.91 mm. The outer casing 14 was provided on the second outer conductor 13b without providing the third outer conductor 13c. The outer casing body 14 had a thickness of 0.1 mm and was made by extruding a sheath of FEP. The outer diameter of the coaxial cable after extrusion was 1.11 mm. Thus, the coaxial cable of Comparative Example 1 was manufactured.

[Measurement of bending phase]
The bending phases of the coaxial cables of Example 1 and Comparative Example 1 were measured. The measurement was performed using a measurement system as shown in FIG. As for the bending phase, the obtained coaxial cable is cut into a length of 700 mm, the coaxial cable 23 after attaching the connector 24 is bent so as to form a circle having a radius of curvature of 50 mm, and network analysis is performed at a frequency of 26.5 GHz. I got it. For the network analysis, a network analyzer 21 (manufactured by KEYSIGHT Co., Ltd.) was used, and as the measurement cable 22 and the connector 25, those attached to the network analyzer were used. In the network analysis, changes in signal amplitude and phase can be measured by reflection measurement and transmission measurement when a high frequency sine wave signal is incident on the coaxial cable 23. The measurement results of the changed amplitude and phase are calculated inside the network analyzer, and the coaxial cable characteristics (attenuation amount, phase) can be obtained.

With such a network analyzer 21, the initial attenuation, the bending attenuation, the bending return bending, the bending phase bending state, and the bending phase bending back were measured, and the results are shown in Table 1. The numerical value is the average value of 12 measurement samples. Comparing the results of Comparative Example 1 and the results of Example 1, the bending phase showed a small value both in the bent state and in the bending back state. Also, regarding the amount of attenuation, a small value was shown in both the bent state and the unbent state.

10 coaxial cable 11 center conductor 12 insulator 13 outer conductor 13a first outer conductor (first metal resin tape)
13b Second outer conductor (fine metal wire)
13c Third outer conductor (second metal resin tape)
14 Enclosure 20 Bending Phase Measuring Method 21 Nedwork Analyzer 22 Measurement Cable 23 Coaxial Cable for Measurement 24 Connector

Claims (6)

A center conductor, an insulator provided on the outer periphery of the center conductor, a first outer conductor made of a metal resin tape vertically attached to the outer periphery of the insulator, and wound around the outer periphery of the first outer conductor. A second outer conductor formed of a thin metal wire, a third outer conductor formed of a metal resin tape wound around the outer circumference of the second outer conductor, and a third outer conductor wound around the outer circumference of the third outer conductor. A coaxial cable comprising a resin tape and an outer jacket formed by adhering the resin tape to the third outer conductor via a fusion layer. The coaxial cable according to claim 1, wherein the first outer conductor is vertically attached to the insulator so as to partially overlap with each other with a width within a range of 0.1 to 3 mm. The coaxial cable according to claim 1 or 2, wherein the second outer conductor is horizontally wound at a pitch within a range of 10 to 20 mm. The coaxial cable according to any one of claims 1 to 3, wherein the third outer conductor is horizontally wound with a lap of 1/5 to 1/2 at a horizontal winding pitch of 1.5 to 5 mm. The coaxial cable according to any one of claims 1 to 4, wherein the jacket is horizontally wound with a lap of 1/5 to 1/2 at a horizontal winding pitch of 1.5 to 5 mm. The bending phase obtained by bending the coaxial cable having a length of 700 m to form a circle having a radius of curvature of 50 mm and performing a network analysis at a frequency of 26.5 GHz is 8 (deg) or less. The coaxial cable according to any one of 5 above.