JP2000057863A - Coaxial cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit a high frequency signal at a high speed, obtain sufficient shield effect, and reduce attenuation, by making up an outer conductor layer out of a metallized tape made by forming metal on an insulating tape and winding the metallized tape around a coaxial cable at a specific angle to the longitudinal axis thereof. SOLUTION: A metallized tape is wound around a coaxial cable 1 at 0 to 25 deg. to the longitudinal axis thereof. The coaxial cable 1 is equipped with a dielectric layer 5 formed by winding a porous tetrafluoroethylene resin tape 3 around an inner conductor 2 made up of silvered annealed copper wire at a center part and extrudingly coating it with thin-walled FEP, as a skin layer 4. A drain wire 6 is longitudinally attached to the dielectric layer 5, and, as an outer conductor layer 7, an aluminum polyester tape made by depositing Al on an insulating tape, or by sticking Al foil thereto, as metal for metallization, is wound around the dielectric layer 5 and drain wire 6, and further, it is covered by an insulating outer cladding 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coaxial cable used for a high-frequency signal transmission line or the like, and more particularly to a coaxial cable having an improved shield effect and attenuation.

[0002]

2. Description of the Related Art Conventionally, high-frequency signal transmission coaxial cables have been used as signal transmission lines for use in, for example, computers or measuring instruments. Such a coaxial cable
In bulls, as transmission signals become higher in frequency, that is, higher in bit rate, higher speed signal transmission is also required. Heretofore, in this type of coaxial cable, for example, a dielectric made of a porous fluororesin having a low dielectric constant is provided around an inner conductor, and a dielectric is formed around the dielectric so as to enable high-speed signal transmission. As the external conductor, a metal tape such as aluminum or copper is deposited on a horizontal wound shield layer, a braided shield layer or an insulating tape made of a conductor element wire, or a metal tape obtained by bonding these foils is used. It is known that the wire is wound and an insulating jacket is provided around the wire.

However, such a signal transmission coaxial cable as described above is used.
In order to enable high-speed signal transmission, various proposals have been made to maintain the porosity of the porous fluororesin as a dielectric material high and to reduce the dielectric constant. In order to enhance the shield effect and reduce the attenuation, the outer conductor provided around the dielectric as described above can sufficiently improve the shield effect and reduce the attenuation. Was not.

[0004] That is, in order to improve the shield effect or reduce the amount of attenuation, an outer conductor provided around a dielectric disposed around the inner conductor is used as a horizontal wound shield made of a conductor element wire. Although the flexibility is good when the shield layer is provided, it can be used without any problem in a low frequency band of, for example, about 1 MHz, but in a high frequency band such as tens or hundreds of MHz, there is a gap between conductor wires. In the case where a braided shield layer is provided, the shielding effect is improved by increasing the braid density, but the shielding effect is not sufficient. When a metal tape such as aluminum or copper is vapor-deposited, or a metal tape or the like obtained by laminating these foils is provided by winding, a case is formed so that wrinkles can be prevented and the winding can be easily performed. About 3 against the axis of the bull It is wound at an angle of 45 degrees,
Also in this case, a sufficient shield effect or a sufficient reduction in the amount of attenuation could not be obtained, and the reduction in the shield effect and the amount of attenuation was not sufficiently satisfactory.

Therefore, the inventors of the present invention have been able to transmit high-frequency signals, that is, high bit rate signals, at high speed in the above-described coaxial cable, and at the same time, have a sufficient shielding effect and a reduced amount of attenuation. As a result of intensive studies, studies and research on the configuration of the outer conductor that can be
Knowledge that a good shielding effect can be obtained and the amount of attenuation can be reduced by winding a metal tape as an external conductor at a specific angle with respect to the axis of the coaxial cable. Based on the above, the present invention has been completed.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to transmit a high-frequency signal, that is, a high bit rate signal at a high speed. An object of the present invention is to provide a coaxial cable capable of obtaining a sufficient shielding effect and reducing the amount of attenuation.

[0007]

The above object is achieved by a coaxial cable according to the present invention. That is, in summary, the present invention provides a dielectric layer around the inner conductor,
In a coaxial cable in which an outer conductor layer is provided around the dielectric layer, the outer conductor layer is a metallized tape in which a metal is formed on an insulating tape, and the metallized tape is moved in a longitudinal direction of the coaxial cable. A coaxial cable characterized by being wound at an angle of 0 to 25 degrees.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention uses a metallized tape for the outer conductor layer of a coaxial cable, and winds the metallized tape at an angle of 0 to 25 degrees with respect to the longitudinal direction of the coaxial cable. As a result, even when a high bit rate signal is transmitted at a high speed, a sufficient shielding effect can be obtained, and the amount of attenuation can be reduced.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; FIG. 1 is a partial perspective view of one embodiment of a coaxial cable according to the present invention, and FIG.
FIG. 3 is an explanatory diagram for explaining a winding angle of a metallized tape as an outer conductor of the coaxial cable according to the present invention shown in FIG.

Referring to FIG. 1, a coaxial cable according to the present invention is shown.
A coaxial cable 1 is shown at its center, for example, an AWG (American Wire Gauge) #
The inner conductor 2 is made of 30 silver-plated annealed copper wires. Around the inner conductor 2, a porous ethylene tetrafluoride resin tape 3 having a porosity of about 70% and being wound is provided. And a dielectric layer formed by extrusion-coating a thin (eg, about 15 μm) FEP (tetrafluoroethylene-hexafluoropropylene copolymer) as a skin layer 4 around the porous tetrafluoroethylene resin tape. 5 is provided.

Further, a drain line 6 made of a silver-plated soft copper wire is longitudinally attached to the dielectric layer 5, and an outer conductor layer 7 is provided around the dielectric layer 5 and the drain line 6 as a polyester tape of an insulating tape. Alternatively, an aluminum polyester tape or an aluminum polyimide tape (for example, a thickness of about 25 μm) of a metalized tape formed by depositing aluminum as a metal to be metalized on a polyimide tape or pasting an aluminum foil is wound. .
The periphery of the aluminum polyester tape as the outer conductor layer 7 is covered with an insulating jacket 8 of, for example, PVC (polyvinyl chloride).

Here, the winding angle θ of the aluminum polyester tape of the outer conductor 7 wound around the dielectric layer 5 and the drain wire 6 will be described, as shown in FIG. The angle θ is about 0 to 25 degrees with respect to the longitudinal axis direction of the coaxial cable 1 (0 degrees is vertically attached). The shielding effect and attenuation of the coaxial cable manufactured at such a winding angle θ and other winding angles,
The measurement results at various frequencies are shown in Tables 1 and 2, respectively.

[0013]

[Table 1]

[0014]

[Table 2]

As can be seen from Tables 1 and 2, when the winding angle θ is larger than 25 degrees, a sufficient shield effect cannot be obtained, and the attenuation is not sufficiently reduced. The present invention has a great effect on the reduction of the shielding effect and the attenuation in the high frequency region. In addition,
In the above embodiment, an example in which an aluminum polyester tape is used as the metallized tape as the external conductor 7 wound around the dielectric layer 5 and the drain line 6 is shown. Not limited to the aluminum polyester tape, the same as the above embodiment, even when using copper polyester tape or copper polyimide tape of metallized tape formed by depositing copper on polyester tape or polyimide tape, or pasting copper foil, Effects can be obtained. Further, as the metallized tape of the above embodiment, a polyester tape or a polyimide tape using both aluminum and copper may be used, and the lamination order does not matter, but a metallized tape may be used.

Further, in the above embodiment, the dielectric layer is made of porous tetrafluoroethylene resin tape and extrusion-coated F
Although an example using EP has been shown, PTFE (polytetrafluoroethylene),
FEP (tetrafluoroethylene-hexafluoropropylene copolymer), PFA (tetrafluoroethylene-
Perfluoroalkyl vinyl ether copolymer), ET
FE (tetrafluoroethylene-ethylene copolymer),
Alternatively, by using foams of these, a low dielectric constant can be obtained, and favorable electric characteristics can be obtained.

[0017]

As described above, according to the coaxial cable of the present invention, the metalized tape is used as the outer conductor of the coaxial cable, and the coil is wound about 0 to 25 degrees with respect to the longitudinal direction of the coaxial cable. Since the metallized tape is wound at a turning angle, a high-frequency signal, that is, a high bit rate signal can be transmitted at a high speed, a sufficient shielding effect can be obtained, and the amount of attenuation can be reduced. It has an excellent effect that it can be performed.

[0018]

[Brief description of the drawings]

FIG. 1 is a partial perspective view of one embodiment of a coaxial cable according to the present invention.

FIG. 2 is an explanatory view for explaining a winding angle of the metallized tape of the coaxial cable according to the present invention shown in FIG. 1;

[Explanation of symbols]

1: Coaxial cable, 2: Internal conductor, 3: Porous tetrafluoroethylene resin tape, 4: Skin layer, 5: Dielectric layer, 6: Drain wire, 7: External conductor layer, 8:
Insulation jacket.

Claims (1)

[Claims] 1. A coaxial cable having a dielectric layer provided around an inner conductor and an outer conductor layer provided around the dielectric layer, wherein the outer conductor layer is a metallized tape formed by forming a metal on an insulating tape. A coaxial cable, wherein the metallized tape is wound at an angle of 0 to 25 degrees with respect to the longitudinal axis direction of the coaxial cable.