TWI543198B - Hollow core and coaxial cable - Google Patents

Description

Hollow core and coaxial cable

The present invention relates to a hollow core body and a coaxial cable, and more particularly to a hollow core body and a coaxial cable which can preferably transmit a high speed signal with low capacitance (electrostatic capacitance) and which is excellent in mechanical strength.

A hollow core body (601, 602) is known (for example, refer to Patent Document 1), comprising: an inner conductor (1); and an insulating covering body (7) comprising a thermoplastic resin and including the inner conductor (including the inner conductor) 1) an annular portion (7a), a plurality of ribs (7b) extending radially from the inner annular portion (7a), and an annular portion connecting the outer ends of the ribs (7b) ( 7c), and having three or more void portions (G) surrounded by the inner annular portion (7a), the rib portion (7b), and the outer annular portion (7c). An external conductor is disposed outside the hollow core for high speed. Coaxial cable for high-capacity signal transmission.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2011-023205

The above-mentioned hollow core system is assumed to be a configuration of a capacitance of about 80 pF/m, but with the high speed of transmission signals in recent years. Large capacity requires 60pF/m The lower the capacitance. In order to reduce the capacitance by the structure of the above-described hollow core body, the inner annular portion, the rib portion or the outer annular portion may be thinned to increase the void ratio, or the rib portion may be lengthened to increase the inner conductor and the outer conductor. Distance is enough. However, if the inner annular portion, the rib portion or the outer annular portion is thinned or the rib portion is lengthened, the mechanical strength is insufficient, and in particular, the lateral compressive strength (=the strength against the compression of the hollow core body) is lowered. Therefore, there is a problem that localized flattening occurs during processing of the coaxial cable or during cable wiring, resulting in deterioration of electrical characteristics. Accordingly, it is an object of the present invention to provide a hollow core body and a coaxial cable which are capable of transmitting a high-speed ‧ large-capacity signal and having excellent mechanical strength by utilizing a low capacitance of 60 pF/m or less.

In a first aspect, the present invention provides a hollow core body (101, 102), characterized by comprising at least: an inner conductor (1); a first insulating covering body (2) formed of a thermoplastic resin, and comprising The first inner annular portion (2a) covering the inner conductor (1) and the first inner annular portion (2a) and three or more ribs extending radially from the first inner annular portion (2a) a rib (2b) and a first outer annular portion (2c) connecting the outer ends of the first ribs (2b); and a second insulating covering (3) formed of a thermoplastic resin and configured The second inner annular portion (3a) that covers the first insulating covering (2) and the three or more ribs that extend radially from the second inner annular portion (3a) a second rib (3b) and a second outer annular portion (3c) that connects the outer ends of the second rib (3b); and the second inner annular portion (3a) and the second rib (3b) The minimum value of the thickness of the second outer annular portion (3c) is larger than the maximum thickness of the first inner annular portion (2a), the first inner portion (2b), and the first outer annular portion (2c). . In the hollow core body (101, 102) of the first aspect, the first inner annular portion (2a) and the first rib portion are present in the vicinity of the inner conductor (1). (2b) and the first outer annular portion (2c) are thinner than the second inner annular portion (3a), the second rib portion (3b), and the second outer annular portion (3c), and there are three or more Since the gap portion (G1) and the three or more second gap portions (G2) are formed, the gap becomes large. Further, the distance from the inner conductor (1) to the outer circumferential surface of the second outer annular portion (3c) (that is, the position of the outer conductor) also becomes long. Therefore, a low capacitance of 60 pF/m or less can be achieved. Therefore, it can cope with the transmission of high-speed ‧ large-capacity signals. Further, since the second inner annular portion (3a), the second rib portion (3b), and the second outer annular portion (3c) which are subjected to an external force are relatively thick, a sufficiently excellent mechanical strength can be obtained. Therefore, the characteristics are not easily deteriorated even in the case of multi-core twisting or bending.

Furthermore, the hollow core body according to the first aspect of the present invention includes a third insulating covering body which is the same as the second insulating covering body (3) on the outer side of the second insulating covering body (3), or The plurality of insulating coverings (the third insulating covering, the fourth insulating covering, and the like) which are the same as the second insulating covering (3) are provided in the outer side of the second insulating covering (3).

In a second aspect, the present invention provides a hollow core body (103), comprising: an inner conductor (1); and an insulating covering body (5) formed of a thermoplastic resin and configured to include: The inner annular portion (5a) covered by the inner conductor (1) and the first rib (5b) formed by three or more ribs extending radially from the inner annular portion (5a) a first intermediate annular portion (5c) at an outer end of the first rib portion (5b), and a second rib portion composed of three or more ribs radially extending from the first intermediate annular portion (5c) 5d) and an outer annular portion (5e) connecting the outer ends of the second ribs (5d); and the middle annular portion (5c), the second rib portion (5d), and the outer annular portion (5e) The minimum value of the thickness is larger than the maximum value of the thicknesses of the inner annular portion (5a) and the first rib portion (5b). In the second viewpoint above In the hollow core body (103), the inner annular portion (5a) and the first rib portion (5b) existing in the innermost portion of the inner conductor (1) are thinner than the middle annular portion (5c) and the second rib portion (5d). And the outer annular portion (5e), and there are three or more first void portions (G1) and three or more second void portions (G2), so that the voids are increased. Further, the distance from the inner conductor (1) to the outer peripheral surface of the outer annular portion (5e) (i.e., the position of the outer conductor) also becomes long. Therefore, a low capacitance of 60 pF/m or less can be achieved. Therefore, it can cope with the transmission of high-speed ‧ large-capacity signals. Further, since the annular portion (5c), the second rib portion (5d), and the outer annular portion (5e) are relatively thick in the external force, a sufficiently excellent mechanical strength can be obtained. Therefore, the characteristics are not easily deteriorated even in the case of multi-core twisting or bending.

In a third aspect, the present invention provides a hollow core (104), comprising: an inner conductor (1); and an insulating covering (6) formed of a thermoplastic resin and configured to include: The inner annular portion (6a) covered by the inner conductor (1); and the first rib (6b) composed of three or more ribs extending radially from the inner annular portion (6a); When the outermost middle annular portion is the annular portion in the "N" (N is a natural number of 2 or more) and i is a natural number of 1 to N, the first portion is composed of three or more ribs. i) an annular portion of the "i" at the outer end of the rib; and an "i+1" rib formed of three or more ribs extending radially from the annular portion of the first "i"; and An outer annular portion (6 g) at the outer end of the "N+1" rib (ie, the outermost rib) formed by three or more ribs extending radially from the annular portion of the first "N" And the first intermediate ring portion, the second rib portion, the "N" annular portion (that is, the outermost annular portion), the "N+1" rib portion, and the outer annular portion (6g) The minimum thickness is greater than the thickness of the inner annular portion (6a) and the first inner rib portion (6b) Maximum. Hollow core of the above third aspect In the body (104), the inner annular portion (6a) and the first rib portion existing in the innermost portion of the inner conductor (1) are thinner than the first intermediate annular portion, the second rib portion, and the "N" ring. The first "N+1" rib and the outer annular portion (6g), and at least three or more first gap portions (G1) and three or more second gap portions (G2) and three or more Since the third gap portion (G3) is formed, the gap is increased. Further, the distance from the inner conductor (1) to the outer peripheral surface of the outer annular portion (6g) (i.e., the position of the outer conductor) also becomes long. Therefore, a low capacitance of 60 pF/m or less can be achieved. Therefore, it can cope with the transmission of high-speed ‧ large-capacity signals. Further, since the annular portion, the "N+1" rib portion, and the outer annular portion (6g) in the "N" subjected to the external force are relatively thick, a sufficiently excellent mechanical strength can be obtained. Therefore, the characteristics are not easily deteriorated even in the case of multi-core twisting or bending. Further, in the fourth embodiment, the outermost middle annular portion number N=2 is shown, but the outermost middle annular portion number N may be three or more.

According to a fourth aspect, the present invention provides a coaxial cable (200) including the hollow core body according to the first to third aspects, an outer conductor (11) provided on an outer side of the hollow core body, and a view. A jacket layer (12) provided on the outer side of the outer conductor (11) is required. In the coaxial cable (200) of the fourth aspect described above, since the hollow core bodies of the first to third aspects are used, a low capacitance of 60 pF/m or less can be obtained. Therefore, it can cope with the transmission of high-speed ‧ large-capacity signals. Also, a sufficiently excellent mechanical strength can be obtained.

According to the hollow core body and the coaxial cable of the present invention, it is possible to achieve a low capacitance of 60 pF/m or less, and a sufficiently excellent mechanical strength can be obtained. Therefore, it can cope with the transmission of high-speed ‧ large-capacity signals, and even in the case of multi-core coupling or bending The shape characteristics are also not easily deteriorated.

1‧‧‧Internal conductor

2‧‧‧1st insulating covering

2a‧‧‧1st inner ring

2b, 5b, 6b‧‧‧1st rib

2c‧‧‧1st outer ring

3‧‧‧2nd insulating covering

3a‧‧‧2nd inner ring

3b, 5d, 6d‧‧‧2nd rib

3c‧‧‧2nd outer ring

4‧‧‧3rd insulating covering

4a‧‧‧3rd inner ring

4b, 6f‧‧‧3rd rib

4c‧‧‧3rd outer ring

5,6,7‧‧‧Insulating coverings

5a, 6a, 7a‧‧‧ inner ring

5c‧‧‧ middle ring

5e, 6g, 7c‧‧‧ outer ring

6c‧‧‧1st middle ring

6e‧‧‧2nd middle ring

7b‧‧‧ ribs

10, 101~104, 601, 602‧‧‧ hollow core

11‧‧‧External conductor

12‧‧‧ sheath layer

20, 24‧‧‧ traction machine

21‧‧‧Extrusion molding machine

22‧‧‧Mold

23‧‧‧ chiller

200‧‧‧ coaxial cable

G‧‧‧Voids

G1‧‧‧1st gap

G2‧‧‧2nd gap

G3‧‧‧3rd gap

Fig. 1 is a cross-sectional view showing a hollow core body of Example 1.

Fig. 2 is a graph showing a numerical example of the hollow core body of the first embodiment.

Fig. 3 is a block diagram showing the steps of manufacturing the intermediate hollow core of the first embodiment.

4(a) and 4(b) are cross-sectional views showing the inner conductor and the intermediate hollow core of the first embodiment.

Fig. 5 is a block diagram showing the steps of manufacturing the hollow core body of the first embodiment.

Fig. 6 is a cross-sectional view showing the hollow core of the second embodiment.

Fig. 7 is a graph showing a numerical example of the hollow core of the second embodiment.

Figure 8 is a cross-sectional view showing the hollow core of Example 3.

Fig. 9 is a graph showing a numerical example of the hollow core of Example 3.

Figure 10 is a cross-sectional view showing the hollow core of Example 4.

Fig. 11 is a graph showing a numerical example of the hollow core of Example 4.

Fig. 12 is a perspective view showing the coaxial cable of the fifth embodiment.

Fig. 13 is a cross-sectional view showing the hollow core of Comparative Example 1.

Fig. 14 is a graph showing a numerical example of the hollow core of Comparative Example 1.

Fig. 15 is a cross-sectional view showing the hollow core of Comparative Example 2.

Fig. 16 is a graph showing a numerical example of the hollow core of Comparative Example 2.

Hereinafter, the present invention will be described in more detail by way of embodiments shown in the drawings. Furthermore, the invention is not limited thereby.

[Examples] - Example 1

1 is a cross-sectional view of a hollow core 101 of Embodiment 1. The hollow core body 101 includes an inner conductor 1, a first insulating covering 2, and a second insulating covering 3.

The inner conductor 1 is a single wire or a stranded wire.

The first insulating covering 2 contains a thermoplastic resin and includes a coating a first inner annular portion 2a of the partial conductor 1, a plurality of first rib portions 2b extending radially from the first inner annular portion 2a, and a first outer ring connecting the outer ends of the plurality of first rib portions 2b The shape 2c has three or more first gap portions G1 surrounded by the first inner annular portion 2a, the first rib portion 2b, and the first outer annular portion 2c.

As the thermoplastic resin, for example, a tetrafluoroethylene-perfluoroalkyl group can be used. Fluorine resin such as polyvinyl ether copolymer (PFA, Polyfluoroalkoxy), fluorinated ethylene propylene (FEP, Fluorinated Ethylene Propylene), polyethylene (PE, polyethylene) or polypropylene (PP) , Polypropylene) and other polyolefin resins.

The second insulating covering 3 contains a thermoplastic resin and includes a coating The second inner annular portion 3a of the insulating covering 2, the plurality of second ribs 3b extending radially from the second inner annular portion 3a, and the second outer end connecting the plurality of second ribs 3b The outer annular portion 3c has three or more second gap portions G2 surrounded by the second inner annular portion 3a, the second rib portion 3b, and the second outer annular portion 3c. As the thermoplastic resin, for example, a fluorine resin or a polyolefin resin can be used. Furthermore, the first insulating covering 2 and the second insulating covering 3 may be made of the same material or different materials.

The second inner annular portion 3a, the second rib portion 3b, and the second outer annular portion 3c The minimum value of the thickness is larger than the first inner annular portion 2a, the first rib portion 2b, and the first outer ring shape. The maximum thickness of the portion 2c.

A numerical example is shown in FIG. The inner conductor 1 is a single bare copper wire line. The first insulating covering 2 and the second insulating covering 3 are fluororesins. The capacitance was measured using a cable capacitance monitor of TAKIKAWA Engineering Co., Ltd. The compression deformation strength was measured in the same manner as the method described in the above-mentioned Patent Document 1 (Japanese Patent Laid-Open Publication No. 2011-023205), using a precision universal testing machine of Shimadzu Corporation. However, the size of the compression jig is 10 mm x 10 mm.

A method of manufacturing the hollow core body 101 will be described with reference to Figs. 3 to 5 . Bright. As shown in FIG. 3, the inner conductor 1 is conveyed by the tractor 20, and the first insulating covering 2 is formed on the outer circumference of the inner conductor 1 through the die 22 and the cooler 23 of the extrusion molding machine 21, and is pulled by the tractor 24. The hollow core 10 is manufactured. 4(a) is a cross-sectional view of the inner conductor 1, and FIG. 4(b) is a cross-sectional view of the hollow core 10. The manufacturing method of the hollow core body 10 is the same as the manufacturing method described in the above-mentioned patent document 1 (Japanese Patent Laid-Open Publication No. 2011-023205).

Then, as shown in FIG. 5, the hollow core 10 is transferred by the tractor 20, The second insulating covering 3 is formed on the outer periphery of the hollow core 10 by the die 22 and the cooler 23 of the molding machine 21, and the hollow core 101 manufactured by the tractor 24 is pulled. In this way, the hollow core 101 can be manufactured.

Furthermore, the tractor 20, the extrusion molding machine 21, and the mold of Figs. 3 and The device 22, the cooler 23 and the tractor 24 can be the same device. However, the conveying speeds of the tractor 20 and the tractor 24, the resin extrusion conditions in the extrusion molding machine 21, and the cooling conditions of the cooler 23 are different.

According to the hollow core body 101 of Embodiment 1, 60 pF/m or less can be achieved It is low in capacitance and can obtain sufficiently excellent mechanical strength. Also, although it is 2 The stroke (the hollow core body 101 is manufactured by the manufacturing apparatus twice) is manufactured, but the mold 22 can be manufactured using an existing manufacturing apparatus.

- Example 2

Figure 6 is a cross-sectional view of the hollow core 102 of Example 2. The hollow core body 102 includes an inner conductor 1, a first insulating covering 2, a second insulating covering 3, and a third insulating covering 4.

The inner conductor 1 is a single wire or a stranded wire.

The first insulating covering 2 contains a thermoplastic resin and includes a coating a first inner annular portion 2a of the partial conductor 1, a plurality of first rib portions 2b extending radially from the first inner annular portion 2a, and a first outer ring connecting the outer ends of the plurality of first rib portions 2b The shape 2c has three or more first gap portions G1 surrounded by the first inner annular portion 2a, the first rib portion 2b, and the first outer annular portion 2c. As the thermoplastic resin, for example, a fluorine resin or a polyolefin resin can be used.

The second insulating covering 3 contains a thermoplastic resin and includes a coating The second inner annular portion 3a of the insulating covering 2, the plurality of second ribs 3b extending radially from the second inner annular portion 3a, and the second outer end connecting the plurality of second ribs 3b The outer annular portion 3c has three or more second gap portions G2 surrounded by the second inner annular portion 3a, the second rib portion 3b, and the second outer annular portion 3c. As the thermoplastic resin, for example, a fluorine resin or a polyolefin resin can be used.

The third insulating covering 4 contains a thermoplastic resin and includes a coating 2, the third inner annular portion 4a of the insulating covering 3, the plurality of third ribs 4b radially extending from the third inner annular portion 4a, and the third end of the outer end connecting the plurality of third ribs 4b The outer annular portion 4c has the third inner annular portion 4a, the third rib portion 4b, and the third outer portion Three or more second gap portions G3 surrounded by the annular portion 4c. As the thermoplastic resin, for example, a fluorine resin or a polyolefin resin can be used.

Furthermore, the first insulating covering 2, the second insulating covering 3, and the third The insulating covering 4 can be the same material or different materials.

The second inner annular portion 3a, the second rib portion 3b, and the second outer annular portion 3c The minimum value of the thickness is larger than the maximum thickness of the first inner annular portion 2a, the first rib portion 2b, and the first outer annular portion 2c. Further, the minimum values of the thicknesses of the third inner annular portion 4a, the third rib portion 4b, and the third outer annular portion 4c are larger than the second inner annular portion 3a, the second rib portion 3b, and the second outer annular portion 3c. The maximum thickness.

A numerical example is shown in FIG.

According to the hollow core body 102 of Embodiment 2, it is possible to achieve 60 pF/m or less It is low in capacitance and can obtain sufficiently excellent mechanical strength. Further, although the hollow core 102 is manufactured by three steps (three times by the manufacturing apparatus), the mold 22 can be manufactured using an existing manufacturing apparatus.

- Modification of Embodiment 2 -

Alternatively, after the hollow core body 102 is manufactured by three strokes, one stroke or a plurality of strokes may be added, and the insulating covering body may have four or more layers.

- Example 3

Figure 8 is a cross-sectional view of the hollow core body 103 of Example 3. The hollow core body 103 is composed of an inner conductor 1 and an insulating covering 5 .

The inner conductor 1 is a single wire or a stranded wire.

The insulating covering 5 contains a thermoplastic resin and includes a coated inner guide. The inner annular portion 5a, the plurality of first rib portions 5b radially extending from the inner annular portion 5a, and the annular portion 5c connected to the outer end of the first rib portion 5b, from the middle ring The plurality of second ribs 5d extending radially, and the annular portion 5e connecting the outer ends of the second ribs 5d, and having the inner annular portion 5a, the first rib 5b, and the middle Three or more first gap portions G1 surrounded by the annular portion 5c, and three or more second gap portions G2 surrounded by the intermediate annular portion 5c, the second rib portion 5d, and the outer annular portion 5e. As the thermoplastic resin, for example, a fluorine resin or a polyolefin resin can be used.

The thickness of the middle annular portion 5c, the second rib portion 5d, and the outer annular portion 5e The small value is larger than the maximum thickness of the inner annular portion 5a and the first rib portion 5b.

A numerical example is shown in FIG. Capacitance and compressive deformation strength and examples 1 is the same.

According to the hollow core body 103 of Embodiment 3, it is possible to achieve 60 pF/m or less It is low in capacitance and can obtain sufficiently excellent mechanical strength. Further, in addition to the mold, it can be manufactured using an existing manufacturing apparatus. Further, although the mold must be reworked, the hollow core body 103 can be manufactured by one stroke (the hollow core body 103 can be manufactured only once by the manufacturing apparatus).

- Modification of Embodiment 3 -

After the hollow core body 103 is manufactured, the mold of the third embodiment or the mold of the first embodiment may be added one or more times, and the insulating coating 5 or the insulating coating of the first embodiment may be overlapped on the outer side of the insulating covering 5. Body 3.

- Example 4

Figure 10 is a cross-sectional view of the hollow core 104 of Example 4. The hollow core 104 The inner conductor 1 and the insulating covering 6 are included.

The inner conductor 1 is a single wire or a stranded wire.

The insulating covering 6 contains a thermoplastic resin and includes a coated inner guide. The inner annular portion 6a of the body 1, the plurality of first rib portions 6b extending radially from the inner annular portion 6a, and the first intermediate annular portion 6c connecting the outer ends of the first rib portions 6b, The first intermediate annular portion 6c has a plurality of second rib portions 6d extending radially, a second intermediate annular portion 6e that connects the outer ends of the second rib portions 6d, and is radiated from the second intermediate annular portion 6e. a plurality of third ribs 6f extending in a shape and an annular portion 6g connected to an outer end of the third rib 6f, and having an inner annular portion 6a, a first rib portion 6b, and a first middle annular portion Three or more first gap portions G1 surrounded by 6c, three or more second gap portions G2 surrounded by the first intermediate annular portion 6c, the second rib portion 6d, and the second intermediate annular portion 6e, and the second Three or more third gap portions G3 surrounded by the intermediate annular portion 6e, the third rib portion 6f, and the outer annular portion 6g. As the thermoplastic resin, for example, a fluorine resin or a polyolefin resin can be used.

The minimum thickness of the first intermediate portion 6c and the second rib 6d is greater than The maximum thickness of the inner annular portion 6a and the first rib portion 6b, and the minimum thickness of the second intermediate annular portion 6e, the third rib portion 6f, and the outer annular portion 6g is larger than the first intermediate annular portion 6c And the maximum thickness of the second rib 6d.

A numerical example is shown in FIG.

According to the hollow core body 104 of the embodiment 4, low capacitance of 60 pF/m or less can be achieved, and sufficiently excellent mechanical strength can be obtained. Further, in addition to the mold, it can be manufactured using an existing manufacturing apparatus. Further, although the mold has to be reworked, the hollow core 104 can be manufactured by one stroke (the hollow core 104 can be manufactured only once by the manufacturing apparatus). Further, the fourth embodiment corresponds to the case where the outermost middle annular portion is numbered N=2 in the third item of the patent application.

- Example 5 -

The configuration of the hollow core body 104 of the fourth embodiment may be expanded, and one or more intermediate portions may be added between the first intermediate ring portion 6c and the second intermediate annular portion 6e. In other words, in the third item of the patent application, the outermost middle annular portion number N=3 or more is provided, and three or more of the inner annular portion 6a and the outer annular portion 6g are provided. Middle ring.

- variants of embodiments 4 and 5 -

After the hollow core body 104 of the fourth embodiment or the hollow core body of the fifth embodiment is produced, the mold used in the examples 4 and 5 or the mold of the third embodiment or the mold of the first embodiment may be added one or more times. In the process, the insulating covering 6 or the insulating covering 5 of the third embodiment or the insulating covering 3 of the first embodiment is overlapped on the outer side of the insulating covering 6.

- Example 6 -

Figure 12 is a perspective view of the coaxial cable 200 of the sixth embodiment. The coaxial cable 200 is formed by providing the outer conductor 11 on the outer side of the hollow core body of the hollow core body 101 to the fifth embodiment of the first embodiment, and providing the sheath layer 12 on the outer side of the outer conductor 11.

The outer conductor 11 is a plastic tape or a metal foil provided with a metal layer on at least one side, a braided shield, a wound shield, a plating film, or the like, or a composite thereof. The sheath layer 12 is fluorinated ethylene propylene (FEP) or the like.

According to the coaxial cable 200 of the embodiment 6, the low capacitance of 60 pF/m or less can be achieved, and sufficiently excellent mechanical strength can be obtained.

-Comparative Example 1

Figure 13 is a cross-sectional view showing a hollow core 601 of Comparative Example 1. The hollow core 601 is composed of an inner conductor 1 and an insulating covering 7.

The inner conductor 1 is a single wire or a stranded wire.

The insulating covering 7 includes a thermoplastic resin, and includes an inner annular portion 7a covering the inner conductor 1, a plurality of rib portions 7b extending radially from the inner annular portion 7a, and an outer end connecting the outer ends of the rib portions 7b. The outer annular portion 7c has three or more void portions G surrounded by the inner annular portion 7a, the rib portion 7b, and the outer annular portion 7c.

A numerical example is shown in FIG. The hollow core 601 has sufficiently excellent mechanical strength. However, low capacitance of 60 pF/m or less cannot be achieved.

-Comparative Example 2

Figure 15 is a cross-sectional view showing a hollow core 602 of Comparative Example 2. The hollow core 602 is composed of an inner conductor 1 and an insulating covering 7.

The inner conductor 1 is a single wire or a stranded wire.

The insulating covering 7 includes a thermoplastic resin, and includes an inner annular portion 7a covering the inner conductor 1, a plurality of rib portions 7b extending radially from the inner annular portion 7a, and an outer end connecting the outer ends of the rib portions 7b. The outer annular portion 7c has three or more void portions G surrounded by the inner annular portion 7a, the rib portion 7b, and the outer annular portion 7c.

A numerical example is shown in FIG. The hollow core 602 can achieve a low capacitance of 60 pF/m or less. However, since the rib 7b is thin and long, sufficient mechanical strength cannot be obtained.

(industrial availability)

The hollow core and coaxial cable of the invention can be utilized for high speed. High capacity Signal transmission.

1‧‧‧Internal conductor

2‧‧‧1st insulating covering

2a‧‧‧1st inner ring

2b‧‧‧1st rib

2c‧‧‧1st outer ring

3‧‧‧2nd insulating covering

3a‧‧‧2nd inner ring

3b‧‧‧2nd rib

3c‧‧‧2nd outer ring

10‧‧‧ hollow core

101‧‧‧ hollow core

G1‧‧‧1st gap

G2‧‧‧2nd gap

Claims (4)

A hollow core body (101, 102), characterized in that it comprises at least: an inner conductor (1); a first insulating covering body (2) formed of a thermoplastic resin, and configured to include: the inner conductor (1) a first inner annular portion (2a) to be covered, a first rib portion (2b) composed of three or more ribs extending radially from the first inner annular portion (2a), and a first outer annular portion (2c) connecting the outer ends of the first ribs (2b); and a second insulating covering (3) formed of a thermoplastic resin and including: the first insulating layer a second inner annular portion (3a) covered by the covering body (2), and a second rib portion (3b) composed of three or more ribs extending radially from the second inner annular portion (3a) And a second outer annular portion (3c) that connects the outer ends of the second ribs (3b); and the second inner annular portion (3a), the second rib portion (3b), and the second outer annular portion The minimum value of the thickness of (3c) is larger than the maximum value of the thicknesses of the first inner annular portion (2a), the first rib portion (2b), and the first outer annular portion (2c). A hollow core body (103), comprising: an inner conductor (1); and an insulating covering body (5) formed of a thermoplastic resin and configured to include the inner conductor (1) The inner annular portion (5a), the first rib portion (5b) composed of three or more ribs extending radially from the inner annular portion (5a), and the first rib portion (5b) a first intermediate annular portion (5c) at the outer end, a second rib portion (5d) composed of three or more ribs extending radially from the first intermediate annular portion (5c), and a connecting portion An outer annular portion (5e) at an outer end of the rib (5d); and a minimum thickness of the intermediate annular portion (5c), the second rib portion (5d), and the outer annular portion (5e) is greater than The maximum value of the thickness of the inner annular portion (5a) and the first rib portion (5b). A hollow core body (104), comprising: an inner conductor (1); an insulating covering body (6) formed of a thermoplastic resin, and configured to include: coating the inner conductor (1) The inner annular portion (6a); the first rib portion (6b) composed of three or more ribs extending radially from the inner annular portion (6a); and the outermost middle annular portion When the ring portion (N is a natural number of 2 or more) in the first "N" and i is a natural number of 1 to N, the first end of the "i" rib portion composed of three or more ribs is connected. The "i"" rib portion formed by the ribs extending radially from the annular portion of the "i"; and the connection from the "N" The intermediate annular portion is an outer annular portion (6g) at the outer end of the "N+1" rib (ie, the outermost rib) formed by three or more ribs extending radially; and the first intermediate ring The minimum value of the thickness of the annular portion (ie, the outermost annular portion) and the "N+1" rib portion and the outer annular portion (6g) of the second portion and the second "N" portion is greater than The maximum thickness of the inner annular portion (6a) and the first rib portion (6b). A coaxial cable (200) comprising the hollow core body according to any one of claims 1 to 3, and an outer conductor (11) provided on an outer side of the hollow core body.