Dielectric waveguide cable and terminal structure of dielectric waveguide cable

Abstract

To provide a dielectric waveguide cable capable of reducing transmission loss, and a terminal structure of a dielectric waveguide cable capable of suppressing reflection at the end of the dielectric waveguide cable.SOLUTION: A dielectric waveguide cable 1 has a core 2 made from a dielectric material, and a cavity 20 extending along a cable longitudinal direction is formed in the center of the core 2 in a cross section perpendicular to the cable longitudinal direction. A terminal structure of the dielectric waveguide cable 1 is configured such that a terminal member 5 having a conical portion 52 is arranged side by side with the dielectric waveguide cable 1, and an axial hole 50 having a tapered portion 502b whose inner diameter becomes smaller toward a tip of the conical portion 52 is formed in the terminal member 5, and the cavity 20 of the dielectric waveguide cable 1 and the axial hole 50 of the terminal member 5 are in communication with each other. Alternatively, at least one linear dielectric 23 having an outer diameter smaller than an inner diameter of the cavity 20 is accommodated in the cavity 20 at an end of the dielectric waveguide cable 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a dielectric waveguide cable having a waveguide formed of a dielectric, and a terminal structure of the dielectric waveguide cable.

Background Art

[0002] Conventionally, in order to transmit high-frequency signals such as millimeter waves, there is a device that uses a dielectric having a high dielectric constant and a low dielectric loss tangent as a signal transmission medium. In the dielectric waveguide described in Patent Document 1, a resin such as PTFE (polytetrafluoroethylene) is used as the signal transmission medium. Further, Patent Document 1 describes that the dielectric waveguide is composed of a dielectric waveguide main body having a circular cross section and a dielectric waveguide end portion formed in a conical shape, and a part of the dielectric waveguide main body is fitted into a fitting hole provided in a connector.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, against the background of the high-speedization of mobile communication and the like, there is a demand for a dielectric waveguide cable capable of transmitting higher-frequency signals over a long distance. In order to enable long-distance transmission of high-frequency signals, it is a problem to reduce the transmission loss in the dielectric waveguide cable. In addition, suppressing reflection at the end of the dielectric waveguide cable is also an important problem. Therefore, an object of the present invention is to provide a dielectric waveguide cable capable of reducing transmission loss and a terminal structure of the dielectric waveguide cable capable of suppressing reflection at the end of the dielectric waveguide cable.

Means for Solving the Problems

[0005] In order to solve the above-mentioned problems, the present invention provides a dielectric waveguide cable having a core formed of a dielectric and transmitting electromagnetic waves in the GHz band through the core, wherein a cavity extending along the longitudinal direction of the cable is formed in the center of the core in a cross section perpendicular to the longitudinal direction of the cable.

[0006] Furthermore, for the purpose of solving the above-mentioned problems, the present invention provides a terminal structure of a dielectric waveguide cable that transmits electromagnetic waves in the GHz band by a core formed of a dielectric, wherein the terminal member and the dielectric waveguide cable are arranged side by side so that a central axis of the terminal member made of a dielectric having a conical portion coincides with a central axis of the dielectric waveguide cable, the dielectric waveguide cable has a cavity formed in the center of the core in a cross section perpendicular to the cable longitudinal direction, the terminal member has an axial hole having a tapered portion whose inner diameter becomes smaller toward the tip of the conical portion, and the cavity of the dielectric waveguide cable and the axial hole of the terminal member are connected to each other.

[0007] Furthermore, in order to solve the above-mentioned problems, the present invention provides a terminal structure of a dielectric waveguide cable that transmits electromagnetic waves in the GHz band through a core formed of a dielectric, wherein the terminal member and the dielectric waveguide cable are arranged side by side so that a central axis of the terminal member made of a dielectric having a conical portion coincides with a central axis of the dielectric waveguide cable, the dielectric waveguide cable has a cavity formed in the center of the core in a cross section perpendicular to the cable longitudinal direction, the cavity extending along the cable longitudinal direction, and at least one linear dielectric having an outer diameter smaller than the inner diameter of the cavity is housed in the cavity at an end of the core on the terminal member side. Effect of the Invention

[0008] According to the dielectric waveguide cable of the present invention, it is possible to reduce transmission loss. Also, according to the terminal structure of the dielectric waveguide cable of the present invention, it is possible to suppress reflection at the end of the dielectric waveguide cable. [Brief description of the drawings]

[0009] [Figure 1] 1A is a perspective view showing an example of the configuration of a dielectric waveguide cable according to an embodiment of the present invention, and FIG. [Diagram 2] 1A is a graph showing the results of an analysis of the relationship between the inner and outer diameter ratio and the transmission loss in a dielectric waveguide having a cavity in the center, and FIG. 1B is a cross-sectional view of the dielectric waveguide used in the analysis. [Diagram 3] 1A is a graph showing the results of measuring the transmission loss at a transmission frequency of 28 GHz for the dielectric waveguide cable according to the present embodiment and the dielectric waveguide cable according to the comparative example, and FIG. 1B is a cross-sectional view showing the configuration of the dielectric waveguide cable according to the comparative example. [Figure 4] 13 is a graph showing the results of measuring S21 from 21 GHz to 40 GHz for a transmission frequency of dielectric waveguide cables of different cable lengths. [Diagram 5] 1(a) and 1(b) are configuration diagrams showing a first configuration example of a terminal structure of a dielectric waveguide cable. [Figure 6] 6(a) to 6(c) are configuration diagrams showing a second configuration example of a terminal structure of a dielectric waveguide cable. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Embodiment Mode] Fig. 1(a) is a perspective view showing a configuration example of a dielectric waveguide cable 1 according to an embodiment of the present invention. Fig. 1(b) is a cross-sectional view taken along line AA in Fig. 1(a). Fig. 1(a) shows an end of the dielectric waveguide cable 1 in a stepped stripped state. Figs. 1(a) and 1(b) show the central axis C of the dielectric waveguide cable 1. 1In the following, the central axis C of the dielectric waveguide cable 1 is 1 The direction along this line is referred to as the cable longitudinal direction. Figure 1(b) shows a cross section of the dielectric waveguide cable 1 perpendicular to the cable longitudinal direction.

[0011] The dielectric waveguide cable 1 is configured to have a core 2 which is a waveguide formed of a dielectric material, and an outer jacket 3 provided on the outer periphery of the core 2, and transmits electromagnetic waves in the GHz band through the core 2. The dielectric waveguide cable 1 according to the present embodiment is particularly suitable for transmitting electromagnetic waves in the range of 20 GHz to 100 GHz, but can also be used for transmitting electromagnetic waves in the range of 100 GHz to 300 GHz.

[0012] The dielectric material constituting the core 2 has a dielectric loss tangent of 1×10 at the frequency of the electromagnetic wave transmitted by the dielectric waveguide cable 1. -3 The resin has a smaller dielectric loss tangent (tan δ, also called tangent delta or tan delta) as used herein is an index value indicating the ratio of a part of the energy that becomes heat when an AC electric field is applied to a dielectric, and the smaller the loss, the smaller the dielectric loss tangent value. More specifically, the resin constituting the core 2 may be any one of fluororesin, foamed fluororesin, polyethylene, foamed polyethylene, polypropylene, and foamed polypropylene.

[0013] A cavity 20 extending along the cable longitudinal direction is formed in the center of the core 2 in a cross section perpendicular to the cable longitudinal direction. The cavity 20 is filled with air (atmosphere). The dielectric tangent of air is generally lower than the dielectric tangent of resin, and electromagnetic waves transmitted by the core 2 propagate primarily through the center, so that the cavity 20 formed in the center of the core 2 reduces loss.

[0014] As shown in FIG. 1(b), the outer diameter of the dielectric waveguide cable 1 is D 1 , the inner diameter of the cavity 20 is Di, the outer diameter of the cable D 1 Ratio to (Di / D 1) is between 20% and 40%. 1 If Di / D is less than 20%, the cross-sectional area of ​​the cavity 20 in a cross section perpendicular to the cable longitudinal direction becomes small, and the effect of reducing loss becomes small. 1 If Di / D is greater than 40%, the thickness of the dielectric waveguide cable 1 outside the cavity 20 is reduced, and the effect of confining the electromagnetic waves inside the waveguide is reduced, so that the electromagnetic waves are radiated to the outside of the dielectric waveguide cable 1, resulting in large losses. 1 The effect of suppressing loss is increased when the outer diameter D of the dielectric waveguide cable 1 is in the range of 20% to 40%. 1 is, for example, 10.08 mm, and the inner diameter Di of the cavity 20 is, for example, 3.00 mm.

[0015] In this embodiment, the core 2 is configured to include a dielectric waveguide 21 and a plurality of dielectric waveguides 22 arranged around the dielectric waveguide 21. The dielectric waveguide 21 is a hollow tube having a cavity 20 formed in the center. The outer diameter D of the dielectric waveguide 21 is 21 is, for example, 4.00 mm. The multiple dielectric waveguides 22 are twisted in a spiral shape at an angle to the longitudinal direction of the cable. This configuration of the core 2 improves the flexibility of the dielectric waveguide cable 1.

[0016] The dielectric waveguide 21 and the plurality of dielectric waveguides 22 both have a dielectric loss tangent of 1×10 -3 It is made of a fluororesin having a smaller diameter than that of the dielectric waveguide 22. In order to maintain the shape of the dielectric waveguide 21, it is desirable that the resin material of the dielectric waveguide 21 is harder than the resin material of the dielectric waveguide 22. In this embodiment, the dielectric waveguide 21 is made of PTFE (polytetrafluoroethylene), and the dielectric waveguide 22 is made of FEP (tetrafluoroethylene-hexafluoropropylene copolymer).

[0017] As shown in Figs. 1(a) and (b), the core 2 has 30 dielectric waveguides 22 twisted in a spiral shape around one dielectric waveguide 21 arranged at the center, forming an inner and outer two-layer structure. Of the 30 dielectric waveguides 22, 12 dielectric waveguides 22 in the inner layer are arranged so as to be in contact with the outer peripheral surface 21a of the dielectric waveguide 21, and 18 dielectric waveguides 22 in the outer layer are arranged on the outer peripheral side of the 12 dielectric waveguides 22 in the inner layer. In this embodiment, as shown in Fig. 1(a), the spiral winding direction of the 12 dielectric waveguides 22 in the inner layer is the same as that of the 18 dielectric waveguides 22 in the outer layer, but the winding directions of the multiple dielectric waveguides 22 in the inner layer and the outer layer may be opposite. When the spiral winding direction is the same in the inner layer and the outer layer, the dielectric waveguide cable 1 is easier to bend. When the inner and outer layers have opposite spiral winding directions, the twist of the multiple dielectric waveguides 22 is less likely to loosen, making it easier to obtain the effect of confining the transmitted electromagnetic waves inside the waveguide.

[0018] Each dielectric waveguide 22 has a circular cross section perpendicular to the longitudinal direction and an outer diameter D 22 For example, the diameter D of the core 2 is 1.33 mm. 2 is the outer diameter D of the dielectric waveguide 21 21 and the outer diameter D of the plurality of dielectric waveguides 22 22 In this embodiment, the diameter D of the core 2 is 2 is the outer diameter D of the dielectric waveguide 21 21 The outer diameter D of the four dielectric waveguides 22 is 22 As an example, the outer diameter D 21 is 4.00 mm and the outer diameter D of the dielectric waveguide 22 22 is 1.33 mm, the diameter D of core 2 2 The inner diameter Di of the cavity 20 and the diameter D of the core 2 are 9.32 mm. 2 Ratio to (Di / D 2 ) is the above Di / D 2 (i.e., 20% to 40%). As an example, the inner diameter Di of the cavity 20 of the dielectric waveguide 21 is 3.00 mm, and the diameter D 2If the diameter is 9.32 mm, this percentage is approximately 32%.

[0019] The jacket 3 is composed of a band-shaped pressure winding tape 31 wound around the outer circumference of an assembly of a plurality of (30 in this embodiment) dielectric waveguides 22, and a sheath 32 covering the pressure winding tape 31. The pressure winding tape 31 is spirally wound around the core 2 so that a part of the pressure winding tape 31 overlaps with the other in the width direction. The pressure winding tape 31 prevents the plurality of dielectric waveguides 22 from coming apart during the manufacturing process of the dielectric waveguide cable 1. The sheath 32 protects the core 2 and the pressure winding tape 31. The sheath 32 is formed around the outer circumference of the pressure winding tape 31 by extrusion molding. The pressure winding tape 31 is interposed between the sheath 32 and the core 2, which makes it easier to mold the sheath 32 and improves the flexibility of the dielectric waveguide cable 1. The jacket 3 may be composed of at least one of the pressure winding tape 31 and the sheath 32.

[0020] The material of the pressure winding tape 31 and the sheath 32 may have a higher dielectric loss tangent value than the dielectric waveguide 21 and the dielectric waveguide 22, but it is preferable that the material has a higher strength than the material of the dielectric waveguide 21 and the dielectric waveguide 22. The electromagnetic waves transmitted by the dielectric waveguide cable 1 mainly propagate through the core 2, but may also propagate partly through the pressure winding tape 31 and the sheath 32. The pressure winding tape 31 is made of a seal tape made of a fluororesin such as PTFE. The sheath 32 is made of a fluororesin such as FEP, and is preferably made of a material that is particularly excellent in abrasion resistance and tear resistance. The thickness of the pressure winding tape 31 is, for example, 0.07 mm or more and 0.09 mm or less, and the thickness of the sheath 32 is, for example, 0.25 mm or more and 0.35 mm or less.

[0021] 2(a) is a graph showing the results of an analysis of the relationship between the inner and outer diameter ratio and the transmission loss in a dielectric waveguide having a cavity in the center. In this analysis, as shown in FIG. 2(b), a dielectric waveguide 4 having a cavity 40 in the center is used, and the inner diameter D 40The transmission loss per meter of the dielectric waveguide 4 was analyzed for multiple samples with different outer diameters D 4 The material of the dielectric waveguide 4 has a dielectric loss tangent of 3×10 ―4 The vertical axis of the graph is the transmission loss (dB / m) when an electromagnetic wave of 28 GHz is transmitted through the dielectric waveguide 4, and the horizontal axis of the graph is the 40 / D 4 is the inner and outer diameter ratio of the dielectric waveguide 4. A sample having a value of 0 on the horizontal axis is a sample having a solid structure in which no cavity 40 is formed.

[0022] As shown in this graph, the transmission loss of the dielectric waveguide 4 is small, at 2.4 dB / m or less, when the inner / outer diameter ratio is in the range of 0.2 to 0.4, and the transmission loss is smallest when the inner / outer diameter ratio is 0.3. 40 In this way, when the outer diameter D 4 Inner diameter D 40 By adjusting the ratio of the cavity 40 to an appropriate value, the transmission loss can be reduced more than in the case where the cavity 40 is not formed.

[0023] Fig. 3(a) is a graph showing the results of measuring the transmission loss at a transmission frequency of 28 GHz for the dielectric waveguide cable 1 according to the present embodiment and the dielectric waveguide cable 1A according to the comparative example shown in Fig. 3(b). The dielectric waveguide cable 1A according to the comparative example has seven dielectric waveguides 22 arranged in the center instead of the dielectric waveguide 21 of the dielectric waveguide cable 1 according to the embodiment, and the core 2A is formed by a total of 37 dielectric waveguides 22. The outer diameter D of the dielectric waveguide cable 1A is 1A , the diameter D of the core 2A in the dielectric waveguide cable 1A 2A and the outer diameter D of the dielectric waveguide 22 22 is the outer diameter D of the dielectric waveguide cable 1 according to the embodiment. 1 , diameter D of core 2 2 , and the outer diameter D of the dielectric waveguide 2222 is the same as:

[0024] As shown in the graph of FIG. 3(a), the dielectric waveguide cable 1 according to the embodiment has a cavity 20 formed in the center of the core 2, and therefore has reduced loss compared to the dielectric waveguide cable 1A according to the comparative example.

[0025] Fig. 4 is a graph showing the results of measuring S21 (transmission coefficient from input end to output end) for transmission frequencies from 21 GHz to 40 GHz for dielectric waveguide cables 1 with cable lengths of 2 m, 4 m, 6 m, 8 m and 10 m. As shown in Fig. 4, the dielectric waveguide cable 1 tends to have smaller S21 and larger transmission loss as the cable length increases and as the transmission frequency increases, but overall the transmission loss is kept small.

[0026] Next, two configuration examples of the terminal structure of the dielectric waveguide cable 1 will be described with reference to FIGS.

[0027] 5(a) and (b) are configuration diagrams showing a first configuration example of the terminal structure of a dielectric waveguide cable 1. In the first configuration example, the dielectric waveguide cable 1 is connected to a connector 6 via a hollow terminal member 5. A coaxial-waveguide conversion section 7 is attached to the connector 6, and a coaxial cable 9 is connected to the coaxial-waveguide conversion section 7 via a coaxial connector 8.

[0028] 5(a) shows a state in which the dielectric waveguide cable 1, the terminal member 5, and the connector 6 are arranged with a space therebetween in the axial direction, and FIG. 5(b) shows a state in which the dielectric waveguide cable 1, the terminal member 5, and the connector 6 are assembled. The dielectric waveguide cable 1 and the terminal member 5 are aligned along the central axis C of the dielectric waveguide cable 1. 1 and the central axis C of the terminal member 5 5 In Fig. 5(a) and (b), the central axis C 1 ,C 5 The cross section of the dielectric waveguide cable 1 and the terminal member 5 is shown above the central axis C 1,C 5 The external appearance of the dielectric waveguide cable 1 and the terminal member 5 is shown below.

[0029] At one end of the dielectric waveguide cable 1 on the connector 6 side, 18 dielectric waveguides 22 constituting the outer layer are cut at a first end face 1a together with a pressure wrapping tape 31 and a covering sheath 32, and 12 dielectric waveguides 22 constituting the inner layer are cut at a second end face 1b closer to the connector 6 than the first end face 1a together with the dielectric waveguide 21. The 12 dielectric waveguides 22 and the dielectric waveguide 21 between the first end face 1a and the second end face 1b form a fitting portion 10 to be fitted into a terminal member 5.

[0030] The terminal member 5 has a dielectric loss tangent of 1×10 -3 The terminal member 5 is made of a fluororesin, more specifically, PTFE, which is smaller than the diameter of the terminal member 5. The terminal member 5 is integrally formed with a cylindrical portion 51 and a conical portion 52, and the cylindrical portion 51 and the conical portion 52 are aligned along a central axis C. 5 The cylindrical portion 51 has an outer diameter D 51 The conical portion 52 has a constant outer diameter D 52 The outer diameter D of the cylindrical portion 51 gradually decreases. 51 is the outer diameter D of the dielectric waveguide cable 1 1 The outer diameter D of the cone-shaped portion 52 is equal to 52 is the outer diameter D of the cylindrical portion 51 at the end on the cylindrical portion 51 side. 51 and gradually becomes smaller with increasing axial distance from the cylindrical portion 51. The cone angle θ of the conical portion 52 is, for example, not less than 5° and not more than 15°.

[0031] The terminal member 5 has a central axis C 5The axial hole 50 is formed with the center at the center of the terminal member 5. The axial hole 50 is made up of a fitting portion 501 into which the fitting portion 10 of the dielectric waveguide cable 1 is fitted, a small diameter portion 502 having an inner diameter smaller than that of the fitting portion 501, and a tapered portion 503 between the fitting portion 501 and the small diameter portion 502. The fitting portion 501, the small diameter portion 502, and the tapered portion 503 are aligned with the central axis C of the terminal member 5. 5 The narrow diameter portion 502 is formed on the tip side of the cone-shaped portion 52 relative to the fitting portion 501. 5 In a cross section perpendicular to the surface of the fitting portion 501, the small diameter portion 502, and the tapered portion 503, each have a circular shape. The inner diameter of the tapered portion 503 gradually decreases from the fitting portion 501 side toward the small diameter portion 502 side.

[0032] The length of the fitting portion 501 in the axial direction of the terminal member 5 is equal to the length of the fitting portion 10 of the dielectric waveguide cable 1. The first end face portion 1a of the dielectric waveguide cable 1 is abutted against the rear end face 5a of the terminal member 5 facing the first end face portion 1a. The dielectric waveguide cable 1 and the terminal member 5 are fixed to each other by, for example, additional winding of a tape member made of the same material as the holding winding tape 31 or by a fixing member so that the fitting portion 10 of the dielectric waveguide cable 1 does not come off from the fitting portion 501 of the terminal member 5.

[0033] The fitting portion 501 and the tapered portion 503 are formed in the cylindrical portion 51. A part of the thin-diameter portion 502 is formed in the center of the cylindrical portion 51, and the remaining part is formed in the center of the conical portion 52. The thin-diameter portion 502 has a cylindrical hole portion 502a having a constant inner diameter and a tapered portion 502b whose inner diameter becomes smaller toward the tip of the conical portion 52, and the cylindrical hole portion 502a is formed in the center of the cylindrical portion 51, and the tapered portion 502b is formed in the center of the conical portion 52. The inner diameter of the cylindrical hole portion 502a is equal to the inner diameter of the cavity 20 of the dielectric waveguide 21. The inner diameter of the tapered portion 502b is equal to the inner diameter of the cylindrical hole portion 502a at the end portion on the cylindrical hole portion 502a side, and gradually becomes smaller as it moves away from the cylindrical hole portion 502a in the axial direction.

[0034] The connector 6 has a main body 61 and an attachment portion 62, and the attachment portion 62 is attached to the main body 61 with a plurality of bolts 63. The main body 61 is formed with an accommodation hole 610 that accommodates a part of the cylindrical portion 51 and the conical portion 52 of the terminal member 5. The attachment portion 62 is formed with an insertion hole 620 into which the terminal member 5 is inserted, and a holding member 64 that holds the cylindrical portion 51 of the terminal member 5 is disposed inside the insertion hole 620. The holding member 64 is made of resin, for example PTFE.

[0035] The dielectric waveguide cable 1 and the terminal member 5 are connected to each other by fitting the fitting portion 10 of the dielectric waveguide cable 1 into the fitting portion 501 of the terminal member 5. The fitting portion 10 of the dielectric waveguide cable 1 is fitted to the fitting portion 501 of the terminal member 5, so that the central axis C of the dielectric waveguide cable 1 is aligned with the fitting portion 501 of the terminal member 5. 1 and the central axis C of the terminal member 5 5 5, and the cavity 20 of the dielectric waveguide cable 1 and the axial hole 50 of the terminal member 5 are connected together coaxially along the line 501 to 504, so that the cavity 20 of the dielectric waveguide cable 1 and the axial hole 50 of the terminal member 5 are communicated with each other. The electromagnetic wave that has propagated through the cavity 20 of the dielectric waveguide 21 in the dielectric waveguide cable 1 toward the terminal member 5 is emitted from the cavity 20 at the second end face portion 1b, enters the small-diameter portion 502 of the axial hole 50 of the terminal member 5, and enters the coaxial-waveguide converter 7 via the terminal member 5.

[0036] In this first configuration example of the terminal structure, the reduced diameter portion 502b is formed in the axial hole 50 of the terminal member 5, thereby suppressing the reflection of electromagnetic waves at the terminal portion of the dielectric waveguide cable 1. In other words, if the terminal member 5 does not have the reduced diameter portion 502, the proportion of electromagnetic waves reflected at the end face of the terminal member 5 facing the opening of the cavity 20 increases, but in the first configuration example of the terminal structure, the terminal member 5 has the reduced diameter portion 502 having the reduced diameter portion 502b formed therein, so that the cross-sectional shapes of the dielectric waveguide cable 1 and the terminal member 5 become continuous, and the electric field distribution and magnetic field distribution of the transmitted electromagnetic waves become almost the same, thereby suppressing the reflectance at the end face of the terminal member 5.

[0037] Figures 6(a) to (c) are configuration diagrams showing a second configuration example of the terminal structure of the dielectric waveguide cable 1. Figure 6(a) shows a state in which the dielectric waveguide cable 1, the terminal member 5A, and the connector 6 are arranged with a space therebetween in the axial direction, and Figure 6(b) shows a state in which the dielectric waveguide cable 1, the terminal member 5A, and the connector 6 are combined. Figure 6(c) is a cross-sectional view taken along line BB in Figure 6(b). In Figures 6(a) to (c), components and the like common to those described with reference to Figures 5(a) and (b) are designated by the same reference numerals as those in Figures 5(a) and (b), and duplicated descriptions will be omitted.

[0038] In the second configuration example, the dielectric waveguide cable 1 is connected to the connector 6 via a terminal member 5A. The dielectric waveguide cable 1 and the terminal member 5A are aligned along a central axis C of the dielectric waveguide cable 1. 1 and the central axis C of the terminal member 5A 5 and are arranged side by side in the axial direction so that the ends of the cylindrical portion 51 and the conical portion 52 match. Like the terminal member 5 in the first configuration example, the terminal member 5A is made of a fluororesin such as PTFE, and integrally has a cylindrical portion 51 and a conical portion 52. Also, like the fitting portion 501 of the axial hole 50 of the terminal member 5 in the first configuration example, the terminal member 5A is formed with a fitting hole 500 into which the fitting portion 10 of the dielectric waveguide cable 1 is fitted, but no hole corresponding to the small diameter portion 502 is formed.

[0039] A linear dielectric 23 having an outer diameter smaller than the inner diameter of the cavity 20 is accommodated in the cavity 20 at the end of the core 2 of the dielectric waveguide cable 1 on the terminal member 5A side. The linear dielectric 23 has a dielectric loss tangent of 1×10, similar to the dielectric waveguide 21 and the dielectric waveguide 22. -3 The cavity 20 is made of a resin having an outer diameter smaller than that of the linear dielectric 23, for example, PTFE or FEP. In this example, as shown in FIG. 6(c), three linear dielectric 23 are arranged in the cavity 20. However, the number of linear dielectric 23 is not limited to three, and may be one, two, or four or more. In other words, it is sufficient that at least one linear dielectric having an outer diameter smaller than the inner diameter of the cavity 20 is accommodated.

[0040] The length of the linear dielectric 23 is not particularly limited, but is, for example, 1 to 10 times the outer diameter of the dielectric waveguide cable 1. 1 6(a) and 6(b), the end face 23a of the linear dielectric 23 on the terminal member 5A side is located at the same position as the second end face portion 1b, but the position of the end face 23a of the linear dielectric 23 may be within the fitting portion 10, and a part of the linear dielectric 23 may protrude from the dielectric waveguide 21 to the terminal member 5A side.

[0041] This second configuration example of the terminal structure also suppresses the reflection of electromagnetic waves at the terminal portion of the dielectric waveguide cable 1. That is, in the second configuration example of the terminal structure, since the axial hole 50 is not formed in the terminal member 5A, the linear dielectric 23 is stored in the opening of the cavity 20, and the cross-sectional shapes of the dielectric waveguide cable 1 and the terminal member 5A become continuous, and the electric field distribution and the magnetic field distribution of the propagating electromagnetic waves become similar, so that the reflectance is suppressed. The cross-sectional shape of the linear dielectric 23 stored in the cavity 20 on the opposite side to the terminal member 5A is no longer continuous, but since it is arranged outside the connector 6, the change in the electric field distribution and the magnetic field distribution of the propagating electromagnetic waves is relatively small, and the reflectance is suppressed.

[0042] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiment will be described by using the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiment.

[0043] [1] A dielectric waveguide cable (1) having a core (2) formed of a dielectric and transmitting electromagnetic waves in the GHz band through the core (2), wherein a cavity (20) extending along the cable longitudinal direction is formed in the center of the core (2) in a cross section perpendicular to the cable longitudinal direction.

[0044] [2] The dielectric material forming the core (2) has a dielectric loss tangent of 1×10 at the frequency of the electromagnetic wave transmitted by the core (2). -3 The dielectric waveguide cable (1) according to the above [1], wherein the resin is smaller than

[0045] [3] The inner diameter (Di) of the cavity (20) and the outer diameter (D 1 ) is 20% or more and 40% or less.

[0046] [4] The dielectric waveguide cable (1) according to any of [1] to [3] above, wherein the core (2) has a hollow dielectric waveguide (21) in which the cavity (20) is formed, and a plurality of dielectric waveguide lines (22) arranged around the dielectric waveguide (21), and the plurality of dielectric waveguide lines (22) are twisted in a spiral shape around the outer periphery of the dielectric waveguide (21).

[0047] [5] The dielectric waveguide cable (1) described in [4] above, in which a pressure wrapping tape (31) is wound around the outer circumference of the plurality of dielectric waveguides (22), and the pressure wrapping tape (31) is covered with a sheath (32).

[0048] [6] A terminal structure of a dielectric waveguide cable (1) that transmits electromagnetic waves in the GHz band through a core (2) formed of a dielectric, the central axis (C 5 ) is the central axis (C 1 the terminal member (5) and the dielectric waveguide cable (1) are arranged side by side so as to match a longitudinal axis of the core (2) of the dielectric waveguide cable (1), a cavity (20) extending along the longitudinal direction of the cable is formed in the center of the core (2) in a cross section perpendicular to the longitudinal direction of the cable, and the terminal member (5) is formed with an axial hole (50) having a tapered portion (502b) whose inner diameter becomes smaller toward the tip of the conical portion (52), and the cavity (20) of the dielectric waveguide cable (1) and the axial hole (50) of the terminal member (5) are connected to each other.

[0049] [7] A terminal structure of a dielectric waveguide cable (1) that transmits electromagnetic waves in the GHz band through a core (2) formed of a dielectric, the central axis (C 5 ) is the central axis (C 1 ), the dielectric waveguide cable (1) is formed with a cavity (20) extending along the cable longitudinal direction in the center of the core (2) in a cross section perpendicular to the cable longitudinal direction, and at least one linear dielectric (23) having an outer diameter smaller than the inner diameter of the cavity (20) is accommodated in the cavity (20) at an end of the core (2) on the terminal member (5A) side.

[0050] Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the above embodiments. It should be noted that not all of the combinations of features described in the embodiments are essential to the means for solving the problems of the invention. [Explanation of symbols]

[0051] 1...Dielectric waveguide cable 2...Core 20...Cavity 21...Dielectric waveguide 22...Dielectric waveguide 23...Linear dielectric 3...Outer jacket 31...Wrapping tape 32...Sheath 5,5A...Terminal member 50...shaft hole 502...thin diameter portion 502b...reduced diameter portion 51...cylindrical portion 52…Conical section C 1 ,C 5 ...center axis line

Claims

1. A dielectric waveguide cable having a core formed of a dielectric material, the core transmitting electromagnetic waves in the GHz band, A cavity extending along the cable longitudinal direction is formed in the center of the core in a cross section perpendicular to the cable longitudinal direction. Dielectric waveguide cable.

2. The dielectric material forming the core has a dielectric loss tangent of 1×10 at the frequency of the electromagnetic wave transmitted by the core. －３ It is a resin smaller than 2. The dielectric waveguide cable of claim 1.

3. The ratio of the inner diameter of the cavity to the outer diameter of the cable is 20% or more and 40% or less.

3. The dielectric waveguide cable of claim 2.

4. the core has a hollow dielectric waveguide in which the cavity is formed, and a plurality of dielectric waveguides arranged around the dielectric waveguide; the plurality of dielectric waveguides are twisted in a helical shape around the outer periphery of the dielectric waveguide; 4. A dielectric waveguide cable according to claim 1.

5. a pressure winding tape is wound around the outer circumference of the plurality of dielectric waveguides, and the pressure winding tape is covered with a sheath; 5. The dielectric waveguide cable of claim 4.

6. A terminal structure of a dielectric waveguide cable that transmits electromagnetic waves in the GHz band using a core formed of a dielectric material, the terminal member and the dielectric waveguide cable are arranged side by side such that a central axis of the terminal member made of a dielectric material having a conical portion coincides with a central axis of the dielectric waveguide cable; the dielectric waveguide cable has a cavity formed in a center of the core in a cross section perpendicular to the cable longitudinal direction, the cavity extending along the cable longitudinal direction, The terminal member has a shaft hole having a tapered portion whose inner diameter decreases toward the tip of the conical portion, the cavity of the dielectric waveguide cable is in communication with the axial hole of the terminal member; Termination structure of dielectric waveguide cable.

7. A terminal structure of a dielectric waveguide cable that transmits electromagnetic waves in the GHz band using a core formed of a dielectric material, the terminal member and the dielectric waveguide cable are arranged side by side such that a central axis of the terminal member made of a dielectric material having a conical portion coincides with a central axis of the dielectric waveguide cable; the dielectric waveguide cable has a cavity formed in a center of the core in a cross section perpendicular to the cable longitudinal direction, the cavity extending along the cable longitudinal direction, At least one linear dielectric body having an outer diameter smaller than an inner diameter of the cavity is accommodated in the cavity at the end of the core on the terminal member side. Termination structure of dielectric waveguide cable.

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