JPH09129041A - Coaxial cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sufficient suppressing effect of heat transfer without deteriorating electrical characteristics. SOLUTION: An outer conductor 10 is given a double structure and material quality having electric conductivity is used for an inside outer conductor 11 while material quality having low thermal conductivity and superior mechanical strength is used for an outside outer conductor 10, in the case of a coaxial cable equipped with the tubular outer conductor 10, a central conductor 12 positioned on the center axis of the outer conductor 10, and a dielectric substance 13 interposed between the two conductors. Transmission of signals is carried out, without hindrance, by the central conductor 12, the dielectric substance 13, and the inside outer conductor 11, and heat transfer is suppressed by the outside outer conductor 10. Accordingly, a sufficient suppressing effect of heat transfer is provided without deteriorating electrical characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coaxial cable, and more particularly to a coaxial cable suitable for transmitting a signal to a device placed under a constant temperature environment. A coaxial cable is a cable that bundles a coaxial core consisting of a cylindrical outer conductor and a central conductor at the center of the outer conductor. It has excellent characteristics such as easy impedance uniformity.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing an example of use of a coaxial cable. In this use example, one end of a coaxial cable 4 having a structure in which a coaxial core composed of a cylindrical outer conductor 1 and a center conductor 2 at the center thereof, and a dielectric 3 insulating between the two conductors 1 and 2 is bundled. , Connected to a device (not shown) provided inside the thermostat 5.

[0003] As is well known, the thermostatic bath 5 is for keeping the internal environmental temperature constant. Naturally, a sufficient heat insulation is applied to the bath wall surrounding the four sides. The structure is such that the internal temperature tends to fluctuate due to the effect of heat transmitted through it. Therefore, in order to suppress the transmission of heat from the coaxial cable 4,
Measures were taken such as reducing the diameter of the coaxial cable 4 and increasing the total length of the coaxial cable 4. According to the embodiment, the cross-sectional area of the outer conductor 1 can be reduced, and according to the embodiment, the length of the heat transfer path can be increased.

[0004] The constant temperature environment is not limited to the inside of the thermostat. For example, the environment in a vacuum insulated container that has been cooled at a very low temperature (operating environment of a superconductor) also corresponds to the environment.

[0005]

However, although such measures (,) are effective in terms of the effect of suppressing heat transfer, the smaller the diameter and the longer the total length, the greater the signal attenuation. Therefore, there is a problem to be solved that the electrical characteristics are necessarily deteriorated because of the increase in This is because the transfer of heat and the transfer of signals are performed by the same mechanism in terms of a wave phenomenon, and thus suppressing heat transfer is, in other words, suppressing signal transfer.

Therefore, an object of the present invention is to obtain a sufficient heat transfer suppressing effect without deteriorating the electrical characteristics.

[0007]

The above object is to provide a coaxial cable provided with a cylindrical outer conductor, a central conductor located at the axial center of the outer conductor, and a dielectric material interposed between the two conductors. While making the outer conductor a double structure and making the material of the inner outer conductor electrically conductive,
This can be achieved by the technical matter that the material of the outer conductor on the outside has low thermal conductivity and excellent mechanical strength.

[0008] According to this, the transmission of the signal
The dielectric and the inner outer conductor (made of a material having electrical conductivity) can be used without any problem, and the heat transfer can be performed by the outer outer conductor (made of a material having a low thermal conductivity). Suppressed. Therefore, a sufficient effect of suppressing heat transfer can be obtained without deteriorating the electrical characteristics. Other technical matters (mechanical strength) required for the material of the outer conductor are to prevent mechanical deformation of the parts (center conductor, dielectric and inner conductor) that are in charge of signal transmission. This is a mandatory matter. The mechanical deformation includes, for example, expansion and contraction of the dielectric due to the influence of heat.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external view showing an embodiment of the coaxial cable according to the present invention, and FIG. 2 is a sectional view thereof.
1 and 2, 10 is a cylindrical first outer conductor,
Reference numeral 11 denotes a cylindrical second outer conductor located inside the first outer conductor 10, and the first and second outer conductors 10 and 11 are concentrically arranged. Reference numeral 12 is a central conductor, and the central conductor 12 is arranged concentrically with the first and second outer conductors 10 and 11 via a dielectric 13.

The point of this embodiment is that the outer conductor has a concentric double structure (first outer conductor 10 and second outer conductor 1).
The point 1) and the point that the respective materials of these double-structured outer conductors are adapted to the required function. here,
The required function for the first outer conductor 10 is that the thermal conductivity is low and the mechanical strength is excellent. In this respect, it is desirable to use a metal or some kind of alloy, and for example, titanium (metal), stainless steel (alloy), copper-nickel (alloy), nickel (metal) or the like can be used. It may be appropriately selected in consideration of availability and processing or cost.

The required function for the second outer conductor 11 is that it has good electrical conductivity. In this respect, it is preferable to use a metal, for example, copper, silver, gold, aluminum or the like can be used. Similar to the first outer conductor 10, it may be appropriately selected in consideration of easiness of acquisition and processing or cost. When the signal frequency is high, due to the skin effect, the second outer conductor 11 contributes to signal transmission only up to a predetermined depth from the inner surface of the second outer conductor 11. Therefore, the thickness of the second outer conductor 11 is at least the same predetermined value. The depth may be equal to or more than the depth of the above, and the selected material may be thinned depending on the thickness.

In the coaxial cable having such a structure,
The signal transmission is performed without any trouble by the central conductor 12, the dielectric 13, and the second outer conductor 11, and the first outer conductor 10 does not participate in the signal transmission. On the other hand, since the first outer conductor 10 is in contact with the outside air, heat balance is achieved between the outer surface of the first outer conductor 10 and the outside air. For example, when the outside air temperature is high, the temperature of the outer surface of the first outer conductor 10 increases, but as described above, the first outer conductor 10
Since a material having a low thermal conductivity is used for, the temperature rise on the outer surface is not smoothly transmitted to the second outer conductor 11. Therefore, heat transfer to the second outer conductor 11 is suppressed by the first outer conductor 10, so that a coaxial cable having a sufficient heat transfer suppressing effect can be obtained without deteriorating the electrical characteristics. Of.

[0013]

According to the present invention, the transmission of signals can be performed without trouble by the central conductor, the dielectric and the inner outer conductor, while the heat transmission is suppressed by the outer outer conductor. A useful coaxial cable having a sufficient heat transfer suppressing effect can be obtained without deteriorating the electrical characteristics.

[Brief description of the drawings]

FIG. 1 is an external view of a coaxial cable according to an embodiment.

FIG. 2 is a cross-sectional view of the coaxial cable of one embodiment.

FIG. 3 is a diagram showing a conventional coaxial cable and a usage example thereof.

[Explanation of symbols]

 10: first outer conductor (outer outer conductor) 11: second outer conductor (inner outer conductor) 12: center conductor 13: dielectric

Claims (1)

[Claims] 1. A coaxial cable comprising a cylindrical outer conductor, a central conductor located at the axial center of the outer conductor, and a dielectric material interposed between the two conductors, wherein the outer conductor has a double structure. In addition, the inner outer conductor is made of a material having electrical conductivity, while the outer outer conductor is made of a material having low thermal conductivity and excellent mechanical strength. cable.