JP7684917B2 - Dielectric waveguide connection structure - Google Patents

Description

The present invention relates to a connection structure for connecting two dielectric waveguides to each other.

Metallic waveguides are known as a transmission medium for electromagnetic waves with high frequencies called microwaves (including millimeter waves and quasi-millimeter waves). Metallic waveguides realize the propagation of electromagnetic waves through a cavity surrounded by metal. Therefore, there is very little leakage of electromagnetic waves outside the metal waveguide, and the propagation loss is small. In particular, in the frequency band of millimeter waves (30 GHz to 300 GHz), the propagation loss is very small compared to the coaxial line, which is the transmission medium, so metal waveguides are used as the main transmission medium for the millimeter wave band. However, metal waveguides are also known to be difficult to handle. Since the cavity of a metal waveguide is surrounded by metal, it is difficult to bend the metal waveguide freely, and therefore it is difficult to bend and install the metal waveguide in a narrow environment such as indoors. In addition, the weight per unit length of a metal waveguide is large, and therefore the metal waveguide is not suitable for long-distance transmission.

For this reason, dielectric waveguides have been attracting attention in recent years as a wired transmission medium that does not use metal. Dielectric waveguides are made of a dielectric material and consist of a core and a cladding. The core is a tangible object with an external shape that is significantly longer than its width, like a cable. The cladding is not necessarily a tangible object; for example, if air functions as a cladding, the dielectric waveguide does not have a cladding as a tangible object. In a dielectric waveguide, the relative dielectric constant of the core is greater than the relative dielectric constant of the cladding. Therefore, the electromagnetic wave is confined to the core and its vicinity by the total reflection phenomenon, which allows the formation of a mode in which the electromagnetic wave propagates in the longitudinal direction of the dielectric waveguide, that is, the propagation mode of the electromagnetic wave. Air (relative dielectric constant 1) is often used as the cladding.

The size of the cross section of the dielectric waveguide (i.e., the cross section perpendicular to the propagation direction of the electromagnetic wave) is proportional to the wavelength of the propagating electromagnetic wave. Since the cross section size of the dielectric waveguide is small for millimeter waves, the dielectric waveguide is an easy-to-handle transmission medium. For example, when a dielectric waveguide that propagates an electromagnetic wave of 28 GHz is composed of a core with a relative dielectric constant of 2.3 and an air clad, the cross section of the dielectric waveguide (rectangular for simplicity) is miniaturized to a size of about 3 mm x 6 mm. Since the dielectric waveguide uses a dielectric material that is more flexible than metal, the dielectric waveguide is easier to bend than a metal waveguide, and the weight per unit length is also smaller than that of a metal waveguide. Therefore, there is a possibility that the above-mentioned problems of the metal waveguide can be solved. However, the dielectric waveguide has not yet become widespread as a transmission medium.

One of the reasons why dielectric waveguides have not become widespread is the difficulty of connecting them to each other. When one end face of two different dielectric waveguides is butted against the other end face, connection loss occurs in the connection area between one end face and the other end face due to reflection or radiation of electromagnetic waves. This is caused by an unintentional gap that occurs between one end face and the other end face, or an axial misalignment of the two dielectric waveguides. Therefore, in order to connect two dielectric waveguides to each other without any gaps or axial misalignment, a connection structure for connecting the two dielectric waveguides to each other is required.

A connection structure 800 shown in FIG. 1 is known as a connection structure for connecting two dielectric waveguides to each other. This connection structure 800 includes two metal waveguides 810 and 820, one of which is attached to one end of one dielectric waveguide 910, and the other is attached to one end of the other dielectric waveguide 920. The flange 810a of the one metal waveguide 810 and the flange 820a of the other metal waveguide 820 are screwed together by a screw 830, and as a result, the two metal waveguides 810 and 820 are connected without any gap or axial misalignment. The conversion of the propagation mode of the electromagnetic wave between the dielectric waveguides 910 and 920 and the metal waveguides 810 and 820 is achieved by processing one end of the dielectric waveguides 910 and 920 into a tapered shape (see Non-Patent Document 1). The power loss of the electromagnetic wave due to this conversion is generally small. Therefore, the connection structure 800 can connect the two dielectric waveguides 910 and 920 to each other with low loss. However, the connection structure 800 has the following problems. First, because the metal waveguides 810 and 820 are used, the size and weight of the connection structure 800 are both large. The size of the connection structure 800 is regulated by standards. The shape of the mating surface of the flanges 810a and 820a is a square with a side of 22 mm for the UG595 flange and a circle with a diameter of 28.5 mm for the UG381 flange. Both of these have a size several times larger than the cross-sectional size of the above-mentioned millimeter-wave dielectric waveguide, which impairs ease of handling. Furthermore, high processing costs are required for tapering the dielectric waveguides 910 and 920. In addition, the manufacturing cost of the connection structure 800 is high because the manufacturing of the flanges 810a and 820a of the metal waveguides 810 and 820 requires precise metal processing technology.

As a similar technology to this connection structure 800, there is an optical fiber connector for connecting two optical fibers to each other (see Patent Documents 1, 2, and 3). However, the connection structure for a dielectric waveguide differs from the optical fiber connector in the following points.

The frequency band of electromagnetic waves planned to be used in dielectric waveguides is the microwave band (approximately 1 to several hundred GHz), while the frequency band of electromagnetic waves planned to be used in optical fibers is approximately 192 THz. Therefore, the size of a dielectric waveguide is significantly different from the size of an optical fiber. In the case of an optical fiber, the core size that satisfies the single mode condition is typically about 9 μm in diameter, while in the case of a dielectric waveguide, the core size is at most about 1 mm. The size of the core of an optical fiber is extremely small, and it is difficult for a human to handle the core of an optical fiber by hand. For this reason, in optical fibers, a clad with a thickness of about 50 to 100 μm is placed around the core, and further, the clad is usually covered with vinyl or the like. In other words, optical fibers are operated in a situation where there is almost no disturbance to the light propagating through the optical fiber due to touch by a human hand. However, the size of the core of a dielectric waveguide is 1 mm or more, and therefore is large enough to be handled by a human hand. If the core is protected by a clad like an optical fiber and the core-clad size ratio of the optical fiber is followed, the clad thickness is about 10 mm, and the cross-sectional size is relatively large. For example, if a 28 GHz band dielectric waveguide has a clad as a tangible object, the core diameter is about 7 mm, so the clad thickness is 70 mm and the diameter of the dielectric waveguide is 147 mm. Such a thick dielectric waveguide is difficult to bend flexibly, and is heavy due to its size, making it extremely difficult to use as a communication medium. As a result, it is desirable for the dielectric waveguide to be the core itself as a tangible object without a clad as a tangible object. In this case, a notable difference from an optical fiber is that the propagation mode of the electromagnetic wave propagating through the dielectric waveguide is extremely sensitive to external disturbances to the dielectric waveguide (for example, touching with a hand, bringing a metal close, bringing a dielectric close, etc.). Therefore, when configuring a connection structure, it is desirable to pay attention to the electrical parameters (e.g., cladding size, dielectric constant, etc.) of the components that make up the connection structure. In this regard, as described above, optical fibers are insensitive to external disturbances due to their thick cladding and coating, so there is no need to pay attention to the electrical parameters of the components that make up the connection structure. In fact, Patent Documents 1, 2, and 3 do not disclose any attention to the electrical characteristics of the connection structure.

Japanese Patent Publication No. 7-234335 Japanese Patent Application Publication No. 6-118266 Japanese Patent Publication No. 2005-302534

G. E. Ponchak et al., “Design and Analysis of Transitions from Rectangular Waveguide to Layered Ridge Dielectric Waveguide,” IEEE Transactions on Microwave Theory and Techniques (T-MTT), vol. 44, no. 7, pp. 1032 - 1040, Jul. 1996.

As described above, the prior art connection structure has the following two problems.
(1) Because a metal waveguide is used, the size and weight of the connection structure are both large.
(2) It is necessary to tape one end of the dielectric waveguide and to form a flange on the metal waveguide, and therefore the manufacturing cost of the connection structure is high.

The present invention aims to provide a connection structure for connecting two dielectric waveguides to each other that simultaneously solves these two problems.

The technical matters described herein are not intended to explicitly or implicitly limit the invention described in the claims, nor to expressly or implicitly express the possibility of accepting such limitations by those who are not beneficiaries of the present invention (e.g., the applicant and the right holder), but are described simply to facilitate understanding of the gist of the present invention. The outline of the present invention from other perspectives can be understood, for example, from the claims at the time of filing of this patent application.
The connection structure of the present invention is a connection structure for connecting two different dielectric waveguides to each other, and includes a first connector and a second connector. The first connector includes a first terminal formed of a dielectric, a cover attached to the first terminal, and a spring, and the second connector includes a second terminal formed of a dielectric. The first connector and the second connector are connected to each other by mechanically connecting the cover and the second terminal to each other in a snap-fit manner. The spring is held between the first terminal and the cover, and the cover can move along the first terminal in the longitudinal direction of the first terminal by the elasticity of the spring. When the first connector and the second connector are connected to each other, one end face of the first terminal and one end face of the second terminal are pressed against each other by the elasticity of the spring.

According to the present invention, most of the connection structure is made of dielectric material, and almost no metal is used, making it possible to realize a small and lightweight connection structure. Furthermore, since there is no need to taper one end of the dielectric waveguide or form a flange on the metal waveguide, the manufacturing cost of the connection structure is low.

A connection structure using a flanged metal waveguide (prior art). FIG. FIG. 2 is a cross-sectional view of the connection structure of the first embodiment (unconnected). FIG. 2 is a cross-sectional view of the connection structure of the first embodiment (when connected). FIG. The transmission characteristics of a connection structure when the thickness of the core part is changed relative to the thickness of the cladding part. The transmission characteristics of a connection structure when the thickness of the cladding is changed relative to the thickness of the core. FIG. 11 is a cross-sectional view of a connection structure according to a second embodiment (when connected). FIG. 13 is a cross-sectional view of a connection structure according to a third embodiment (when not connected). FIG. 13 is a cross-sectional view of a connection structure according to a third embodiment (when connected). FIG. 13 is a cross-sectional view of a connection structure according to a fourth embodiment (when not connected). FIG. 13 is a cross-sectional view of the connection structure of the fourth embodiment (when connected). 13 is a first application example of the first embodiment (when not connected). 13 shows a first application example of the first embodiment (when connected). 13 shows a second application example of the first embodiment (when not connected). 13 shows a second application example of the first embodiment (when connected). 13 is a modified example of the second application example of the first embodiment (when not connected). 13 is a modified example of the second application example of the first embodiment (when connected). 13 shows a third application example of the first embodiment (when not connected). 13 shows a third application example of the first embodiment (when connected). 13 is a modified example of the third application example of the first embodiment (when not connected). 13 is a modified example of the third application example of the first embodiment (when connected).

An embodiment of the present invention will be described with reference to the drawings. The connection structure of the embodiment is an end face coupling type connection structure that uses a movable snap fit mechanism. The outline and operating principle of the structure will be described below.

First Embodiment
Fig. 2 is a perspective view of the connection structure 100 of the first embodiment. Fig. 3 is a cross-sectional view of the connection structure 100 taken along the cut surface shown in Fig. 2. The connection structure 100 is a connection structure for connecting a first dielectric waveguide 910 and a second dielectric waveguide 920 to each other, and includes a first connector 110 and a second connector 120. In the first embodiment, the first connector 110 is located at one end of the first dielectric waveguide 910, and the second connector 120 is located at one end of the second dielectric waveguide 920.

The first dielectric waveguide 910 is a tangible object made of a dielectric material, and has an external shape in which the length is significantly greater than the width, for example, like a cable (only the vicinity of the end of the first dielectric waveguide 910 is shown in Figures 2-5 and 8-12). The first dielectric waveguide 910 does not have a tangible cladding, but is a tangible core itself. Electromagnetic waves propagate in the longitudinal direction of the first dielectric waveguide 910. The first dielectric waveguide 910 may have a linear shape, or a slightly meandering shape, in other words, a shape with a bend that does not adversely affect the low-loss propagation of the first dielectric waveguide 910. The first dielectric waveguide 910 has a uniform structure in which the shape, size, and material are constant at any position. In this example, the first dielectric waveguide 910 is a tangible object having the shape of an elongated solid rectangular parallelepiped, but is not limited to this and may be, for example, a tangible object having the shape of an elongated solid circular cylinder or an elongated solid elliptical cylinder.

Similarly, the second dielectric waveguide 920 is a tangible object made of a dielectric material, and has an external shape in which the length is significantly larger than the width, for example, like a cable (only the vicinity of the end of the second dielectric waveguide 920 is shown in Figures 2-5 and 8-12). The second dielectric waveguide 920 does not have a tangible clad, but is a tangible core itself. Electromagnetic waves propagate in the longitudinal direction of the second dielectric waveguide 920. The second dielectric waveguide 920 may have a linear shape, or a slightly meandering shape, in other words, a shape with a bend that does not adversely affect the low-loss propagation of the second dielectric waveguide 920. The second dielectric waveguide 920 has a uniform structure in which the shape, size, and material are constant at any position. In this example, the second dielectric waveguide 920 is a tangible object having the shape of an elongated solid rectangular parallelepiped, but is not limited to this and may be, for example, a tangible object having the shape of an elongated solid circular cylinder or an elongated solid elliptical cylinder.

The shape and size of the first dielectric waveguide 910 in a cross section perpendicular to the longitudinal direction of the first dielectric waveguide 910 are the same as the shape and size of the second dielectric waveguide 920 in a cross section perpendicular to the longitudinal direction of the second dielectric waveguide 920. The relative dielectric constant of the second dielectric waveguide 920 is the same as or approximately the same as the relative dielectric constant of the first dielectric waveguide 910.

The first connector 110 includes a first terminal 111, a cover 113 made of a dielectric material, and a metal spring 115. The first terminal 111 includes a first core 111a made of a dielectric material, a first clad 111b made of a dielectric material, and two first guides 111c made of a dielectric material. In this example, the spring 115 is a compression coil spring.

In this example, the first core 111a is a tangible object having the shape of a solid rectangular parallelepiped. The first core 111a has a total of six faces: two end faces that are parallel to each other in the longitudinal direction of the first core 111a (however, the longitudinal direction of the first core 111a is parallel to the propagation direction of the electromagnetic waves), two long side faces that are parallel to each other in a first direction perpendicular to the longitudinal direction of the first core 111a, and two short side faces that are parallel to each other in a second direction perpendicular to both the longitudinal direction and the first direction of the first core 111a. The long side faces are sides whose width (i.e., the length in the first direction) is equal to the length of the long side of the rectangular end face, and the short side faces are sides whose width (i.e., the length in the second direction) is equal to the length of the short side of the rectangular end face.

The first core 111a is connected to one end of the first dielectric waveguide 910 at one of its two end faces. The central axis of the first core 111a in the longitudinal direction is aligned with the central axis of the first dielectric waveguide 910 in the longitudinal direction. The first dielectric waveguide 910 and the first core 111a are not in a twisted positional relationship, that is, the first dielectric waveguide 910 has two side surfaces parallel to each other in the first direction and two side surfaces parallel to each other in the second direction.

When the first core 111a is connected to one end of the first dielectric waveguide 910, it is desirable that the relative dielectric constant of the first core 111a is the same as the relative dielectric constant of the first dielectric waveguide 910 or is a value close to the relative dielectric constant of the first dielectric waveguide 910. Here, "connection" does not deny the presence of one or more intermediate elements between the first core 111a and the first dielectric waveguide 910. An example of such an intermediate element is an adhesive or a pressure-sensitive adhesive used to adhere the first core 111a to the first dielectric waveguide 910. It is desirable that the relative dielectric constant of the adhesive or pressure-sensitive adhesive is the same as the relative dielectric constant of the first dielectric waveguide 910 or is a value close to the relative dielectric constant of the first dielectric waveguide 910.

The first core 111a is not limited to this example, and may be a tangible object having the shape of a solid cylinder or a solid elliptical cylinder. The first core 111a is not limited to this example, and may be one end of the first dielectric waveguide 910, that is, the first core 111a is not an independent component from the first dielectric waveguide 910, but may be a part of the first dielectric waveguide 910 located at one end of the first dielectric waveguide 910.

The first cladding 111b surrounds the first core 111a and is in close contact with the first core 111a. In this example, the first cladding 111b is a tangible object having a hollow rectangular parallelepiped shape, and has a rectangular parallelepiped-shaped through hole that extends in the longitudinal direction of the first core 111a if it were not present (however, the longitudinal direction of the first cladding 111b is parallel to the longitudinal direction of the first core 111a). Specifically, the first cladding 111b has four rectangular flat side walls arranged in a square tube shape, two relatively larger side walls among the four side walls are two large side walls parallel to each other in a third direction perpendicular to the longitudinal direction of the first cladding 111b, and two relatively smaller side walls among the four side walls are two small side walls parallel to each other in a fourth direction perpendicular to both the longitudinal direction and the third direction of the first cladding 111b (usually, the first direction and the third direction are parallel to each other, and the second direction and the fourth direction are parallel to each other). Thus, the first cladding 111b has two frame-shaped end faces parallel to each other in the longitudinal direction of the first cladding 111b. In the longitudinal direction of the first cladding 111b, the central axis of the through hole coincides with the central axis of the first cladding 111b, and in a cross section perpendicular to the longitudinal direction of the first cladding 111b, the four sides of the through hole are parallel to the four sides of the rectangular outer periphery of the first cladding 111b. The first core 111a fits into the through hole of the first cladding 111b. The first cladding 111b is not limited to this example, and is a tangible object having a hollow cylindrical shape when the first core 111a is, for example, a tangible object having a solid cylindrical shape.

The first terminal 111 has a first terminal surface 111s where the first core 111a and the first clad 111b are exposed at one end of the first terminal 111 in the longitudinal direction of the first terminal 111, i.e., the longitudinal direction of the first core 111a. In this example, the other of the two end faces of the first core 111a and one of the two end faces of the first clad 111b are located in a plane perpendicular to the longitudinal direction of the first core 111a, constituting the first terminal surface 111s.

The two first guides 111c have the same shape, specifically, a rectangular flat plate extending in the longitudinal direction of the first core 111a. One first guide 111c is fixed to one of the two large side walls of the first clad 111b, and the other first guide 111c is fixed to the other of the two large side walls of the first clad 111b. One end of the first guide 111c in the longitudinal direction of the first guide 111c (however, the longitudinal direction of the first guide 111c is parallel to the longitudinal direction of the first core 111a) reaches the first terminal surface 111s. The first guide 111c has a first protrusion 111c1 protruding perpendicularly from the first guide 111c at one end of the first guide 111c. Furthermore, the first guide 111c has a second protrusion 111c2 at the center of the first guide 111c that protrudes perpendicularly from the first guide 111c.

In this example, the spring 115 is a square spring that is attached to the outer periphery of the first terminal 111, specifically, it is located between the first convex portion 111c1 and the second convex portion 111c2. The height of the first convex portion 111c1 is sufficient to prevent the spring 115 from falling off the first terminal 111.

The cover 113 includes one main body 113a and two arms 113b. The main body 113a has a hollow rectangular parallelepiped shape and has a rectangular parallelepiped internal space extending in the longitudinal direction of the cover 113 (however, the longitudinal direction of the cover 113 is parallel to the propagation direction of the electromagnetic waves). Specifically, the main body 113a is composed of one rectangular flat bottom and four rectangular flat side walls standing on the four sides of the bottom, and two relatively large side walls of the four side walls are two large side walls that are parallel to each other in a fifth direction perpendicular to the longitudinal direction of the cover 113, and two relatively small side walls of the four side walls are two small side walls that are parallel to each other in a sixth direction perpendicular to both the longitudinal direction and the fifth direction of the cover 113 (usually, the first direction and the fifth direction are parallel to each other, and the second direction and the sixth direction are parallel to each other). The bottom of the main body 113a has a rectangular through hole. The internal space of the main body 113a, which is surrounded by four side walls, is connected to the through hole at the bottom of the main body 113a. In the longitudinal direction of the cover 113, the central axis of the through hole coincides with the central axis of the main body 113a, and in a cross section perpendicular to the longitudinal direction of the cover 113, the four sides of the through hole are parallel to the four sides of the rectangular outer periphery of the main body 113a.

One of the two arms 113b extends in the longitudinal direction of the cover 113 from one end of one of the two large side walls of the main body 113a in the longitudinal direction of the cover 113, and the other of the two arms 113b extends in the longitudinal direction of the cover 113 from one end of the other of the two large side walls of the main body 113a in the longitudinal direction of the cover 113. In this example, the one main body 113a and the two arms 113b are integrally formed. The two arms 113b have the same shape, specifically, a rectangular plate shape extending in the longitudinal direction of the cover 113. The arm 113b has a first protrusion 113b1 protruding inward perpendicularly from the arm 113b near one end of the arm 113b.

A groove 113g is formed on the inner surface of the cover 113, specifically, on the inner surface of the large side wall of the main body 113a, extending linearly in the longitudinal direction of the cover 113. The groove 113g extends from the bottom of the main body 113a to the arm 113b. The bottom surface of the groove 113g and the inner surface of the arm 113b are located on the same plane. The main body 113a has a second protrusion 113a1 that protrudes vertically inward from the bottom surface of the groove 113g in the groove 113g located near the bottom of the main body 113a.

The cover 113 is attached to the first terminal 111 (see FIG. 3). The cover 113 is attached to the first terminal 111 by passing the other end of the first dielectric waveguide 910 to which the first terminal 111 is attached between the two arms 113b of the cover 113 and through the through hole at the bottom of the main body 113a, in that order. During this process, the second convex portion 111c2 of the first guide 111c climbs over the first convex portion 113b1 and the second convex portion 113a1 of the cover 113, and the first convex portion 111c1 of the first guide 111c climbs over the first convex portion 113b1 of the cover 113. When the second protrusion 111c2 of the first guide 111c climbs over the second protrusion 113a1 of the cover 113, the second protrusion 113a1 of the cover 113 fits between the spring 115 and the second protrusion 111c2 of the first guide 111c.

When the cover 113 is attached to the first terminal 111, as shown in FIG. 3, the end of the first terminal 111 connected to the first dielectric waveguide 910 is located in the through hole in the bottom of the cover 113, the first convex portion 111c1 and the second convex portion 111c2 of the first guide 111c fit into the groove 113g of the cover 113, the second convex portion 111c2 is located between the bottom of the cover 113 and the second convex portion 113a1 of the cover 113, and the first convex portion 111c1 is located between the second convex portion 113a1 of the cover 113 and the first convex portion 113b1 of the cover 113. Furthermore, when the cover 113 is attached to the first terminal 111, as shown in FIG. 3, the spring 115 is held between the first terminal 111 and the cover 113. Specifically, the spring 115 is located between the first convex portion 111c1 of the first guide 111c and the second convex portion 113a1 of the cover 113. The upper surface of the first convex portion 111c1 of the first guide 111c is in contact with the groove 113g of the cover 113, and the upper surface of the second convex portion 113a1 of the cover 113 is in contact with the first guide 111c.

When the second convex portion 111c2 of the first guide 111c is in contact with the second convex portion 113a1 of the cover 113 (see FIG. 3), one end of the spring 115 is in contact with the first convex portion 111c1 of the first guide 111c, and the other end of the spring 115 is in contact with the second convex portion 113a1 of the cover 113, and the total length of the spring 115 is shorter than the free length of the spring 115 (the length of the compression coil spring when no load is applied) and longer than the contact length of the spring 115 (the length of the compression coil spring when a load is applied and the wire is in contact in the length direction of the compression coil spring).

Therefore, when the second convex portion 111c2 of the first guide 111c is in contact with the second convex portion 113a1 of the cover 113 (see Figure 3), the spring 115 is subjected to a compressive load by the first convex portion 111c1 of the first guide 111c and the second convex portion 113a1 of the cover 113, and the cover 113 receives a force from the spring 115 in a direction in which the second convex portion 113a1 of the cover 113 moves away from the first convex portion 111c1 of the first guide 111c. However, since the second convex portion 111c2 of the first guide 111c is in contact with the second convex portion 113a1 of the cover 113, the cover 113 does not move. In other words, the range in which the cover 113 can move along the first guide 111c in the longitudinal direction of the first terminal 111 is limited, and the cover 113 is positioned relative to the first terminal 111 with the second protrusion 111c2 of the first guide 111c in contact with the second protrusion 113a1 of the cover 113.

When the second convex portion 111c2 of the first guide 111c is in contact with the second convex portion 113a1 of the cover 113, the total length of the spring 115 is longer than the contact length of the spring 115, so that when a force is applied to the cover 113, the cover 113 can be slid in a direction in which the second convex portion 113a1 of the cover 113 approaches the first convex portion 111c1 of the first guide 111c. When the spring 115 is compressed and the total length of the spring 115 reaches the contact length, or when the second convex portion 111c2 of the first guide 111c contacts the bottom of the main body portion 113a of the cover 113, the sliding of the cover 113 stops. When the force applied to the cover 113 is released, the elasticity of the spring 115 causes the cover 113 to slide in the longitudinal direction of the first dielectric waveguide 910 along the first guide 111, returning to the state shown in FIG. 3, that is, the positioning state described above.

In this way, the first guide 111c and the cover 113 have a limiting mechanism that limits the range within which the cover 113 can move along the first guide 111c in the longitudinal direction of the first terminal 111, and a spring retaining mechanism that holds the spring 115 between the first terminal 111 and the cover 113 and allows the cover 113 to move along the first guide 111 in the longitudinal direction of the first terminal 111 by the elasticity of the spring 115. However, the limiting mechanism is not essential, and if the first guide 111c and the cover 113 do not have a limiting mechanism, the second convex portion 111c2 of the first guide 111c and the second convex portion 113a1 of the cover 113 are not necessary.

The second connector 120 includes a second terminal 121. The second terminal 121 includes a second core 121a formed of a dielectric, a first clad 121b formed of a dielectric, and a first guide 121c formed of a dielectric.

In this example, the second core 121a is a tangible object having a solid rectangular parallelepiped shape. The second core 121a has a total of six faces: two end faces that are parallel to each other in the longitudinal direction of the second core 121a (however, the longitudinal direction of the second core 121a is parallel to the propagation direction of the electromagnetic waves), two long side faces that are parallel to each other in the first direction perpendicular to the longitudinal direction of the second core 121a, and two short side faces that are parallel to each other in the second direction perpendicular to both the longitudinal direction and the first direction of the second core 121a. The long side faces are sides whose width (i.e., length in the first direction) is equal to the length of the long side of the rectangular end face, and the short side faces are sides whose width (i.e., length in the second direction) is equal to the length of the short side of the rectangular end face.

The second core 121a is connected to one end of the second dielectric waveguide 920 at one of its two end faces. The central axis of the second core 121a in the longitudinal direction is aligned with the central axis of the second dielectric waveguide 920 in the longitudinal direction. The second dielectric waveguide 920 and the second core 121a are not in a twisted positional relationship, that is, the second dielectric waveguide 920 has two side surfaces parallel to each other in the first direction and two side surfaces parallel to each other in the second direction.

When the second core 121a is connected to one end of the second dielectric waveguide 920, it is desirable that the relative dielectric constant of the second core 121a is the same as the relative dielectric constant of the second dielectric waveguide 920 or is a value close to the relative dielectric constant of the second dielectric waveguide 920. Here, "connection" does not deny the presence of one or more intermediate elements between the second core 121a and the second dielectric waveguide 920. An example of such an intermediate element is an adhesive or adhesive used to adhere the second core 121a to the second dielectric waveguide 920. It is desirable that the relative dielectric constant of the adhesive or adhesive is the same as the relative dielectric constant of the second dielectric waveguide 920 or is a value close to the relative dielectric constant of the second dielectric waveguide 920.

The second core 121a is not limited to this example, and may be a tangible object having the shape of a solid cylinder or a solid elliptical cylinder. The second core 121a is not limited to this example, and may be one end of the second dielectric waveguide 920. In other words, the second core 121a is not an independent component from the second dielectric waveguide 920, but may be a part of the second dielectric waveguide 920 located at one end of the second dielectric waveguide 920.

The dielectric constant of the second core 121a is the same as or approximately the same as the dielectric constant of the first core 111a.

The second cladding 121b surrounds the second core 121a and is in close contact with the second core 121a. In this example, the second cladding 121b is a tangible object having a hollow rectangular parallelepiped shape, and has a rectangular parallelepiped through hole extending in its longitudinal direction (however, the longitudinal direction of the second cladding 121b is parallel to the longitudinal direction of the second core 121a) if the second core 121a is not present. Specifically, the second cladding 121b has four rectangular flat side walls arranged in a square tube shape, and two relatively large side walls among the four side walls are two large side walls parallel to each other in the third direction perpendicular to the longitudinal direction of the second cladding 121b, and two relatively small side walls among the four side walls are two small side walls parallel to each other in the fourth direction perpendicular to both the longitudinal direction and the third direction of the second cladding 121b. Therefore, the second cladding 121b has two frame-shaped end faces that are parallel to each other in the longitudinal direction of the second cladding 121b. In the longitudinal direction of the second cladding 121b, the central axis of the through hole coincides with the central axis of the second cladding 121b, and in a cross section perpendicular to the longitudinal direction of the second cladding 121b, the four sides of the through hole are parallel to the four sides of the rectangular outer periphery of the second cladding 121b. The second core 121a fits into the through hole of the second cladding 121b. The second cladding 121b is not limited to this example, and is a tangible object having a hollow cylindrical shape when the second core 121a is, for example, a tangible object having a solid cylindrical shape.

The dielectric constant of the second cladding 121b is the same as or approximately the same as the dielectric constant of the first cladding 111b.

The second terminal 121 has a second terminal surface 121s where the second core 121a and the second clad 121b are exposed at one end of the second terminal 121 in the longitudinal direction of the second terminal 121, i.e., the longitudinal direction of the second core 121a. In this example, the other of the two end faces of the second core 121a and one of the two end faces of the second clad 121b are located in a plane perpendicular to the longitudinal direction of the second core 121a, constituting the second terminal surface 121s.

The two second guides 121c have the same shape, specifically, a rectangular flat plate extending in the longitudinal direction of the second core 121a. One second guide 121c is fixed to one of the two large side walls of the second clad 121b, and the other second guide 121c is fixed to the other of the two large side walls of the second clad 121b. One end of the second guide 121c in the longitudinal direction of the second guide 121c (however, the longitudinal direction of the second guide 121c is parallel to the longitudinal direction of the second core 121a) reaches the second terminal surface 121s. The second guide 121c has a recess 121c1 near the other end of the second guide 121c.

The shape and size of the second terminal surface 121s are the same as those of the first terminal surface 111s. Furthermore, the height (vertical length in FIG. 3) of the end portion (excluding the chamfered portion) of the second terminal 121 in a direction perpendicular to the longitudinal direction of the second terminal 121 (i.e., the longitudinal direction of the second core 121a) is equal to the height of the end portion of the first terminal 111 in a direction perpendicular to the longitudinal direction of the first terminal 111 (i.e., the longitudinal direction of the first core 111a) (i.e., the distance between the upper surface of the first convex portion 111c1 of one first guide 111c and the upper surface of the first convex portion 111c1 of the other first guide 111c).

Next, the connection between the first connector 110 and the second connector 120 will be described. With the first terminal surface 111s of the first terminal 111 and the second terminal surface 121s of the second terminal 121 facing each other, the second terminal 121 is pushed between the two arms 113b of the cover 113. The end of the second terminal 121, specifically the chamfered portion of the second guide 121c, comes into contact with the first convex portion 113b1 of the cover 113, thereby widening the gap between the ends of the two flexible arms 113b. When the cover 113 moves along the groove 121cg of the second guide 121c, the first terminal surface 111s and the first convex portion 111c1 of the first terminal 111 come into contact with the second terminal surface 121s of the second terminal 121 and the second guide 121c, respectively. As the cover 113 moves further along the second guide 121c, the spring 115 is compressed, and before the full length of the spring 115 reaches the full length, or before the second protrusion 111c2 of the first guide 111c contacts the bottom of the body 113a of the cover 113, the first protrusion 113b1 of the cover 113 engages with the recess 121c1 of the second guide 121c by the elasticity of the arm 113b, that is, in a snap-fit manner. The first protrusion 113b1 of the cover 113 engages with the recess 121c1 of the second guide 121c, preventing the second terminal 121 from coming off the cover 113 and connecting the first connector 110 and the second connector 120 to each other (see FIG. 4).

When the first protrusion 113b1 of the cover 113 is engaged with the recess 121c1 of the second guide 121c, the elasticity of the spring 115 presses the first terminal surface 111s and the first protrusion 111c1 of the first terminal 111 against the second terminal surface 121s and the second guide 121c of the second terminal 121 that is prevented from coming off the cover 113. In this way, the cover 113 and the second guide 121c have a snap-fit mechanism that mechanically connects them to each other in a snap-fit manner, and the cover 113 that has moved along the second guide 121c and the second guide 121c mechanically connect to each other in a snap-fit manner, thereby connecting the first connector 110 and the second connector 120 to each other. When the first connector 110 and the second connector 120 are connected to each other, the first terminal surface 111s of the first terminal 111 and the second terminal surface 121s of the second terminal 121 are pressed against each other by the elasticity of the spring 115.

When the first connector 110 and the second connector 120 are connected to each other, the longitudinal center axis of the first core 111a is aligned with the longitudinal center axis of the second core 121a, and further, the frame-shaped end face of the first cladding 111b is aligned with the frame-shaped end face of the second cladding 121b.

When the first connector 110 and the second connector 120 are connected to each other, the first terminal surface 111s of the first terminal 111 and the second terminal surface 121s of the second terminal 121 are pressed against each other, so that the electromagnetic waves propagate with low loss. That is, in the connection structure 100, the electromagnetic waves mainly propagate through the core parts (first core 111a and second core 121a) connected to each other and the clad parts (first clad 111b and second clad 121b) connected to each other. Typically, the relative dielectric constant of the clad part is smaller than the relative dielectric constant of the core part. Therefore, a propagation mode is realized in which most of the electromagnetic waves propagating through the connection structure 100 are concentrated in the core part, and the remainder leaks out to the clad part as an evanescent wave. Because the connection structure 100 is not intended to propagate electromagnetic waves in the guide portions (first guide 111c and second guide 121c), it is desirable for the dielectric constant of the guide portions to be smaller than that of the core portion, and it is desirable for the dielectric constant to be equal to or smaller than that of the clad portion. For the same reason, it is desirable for the dielectric constant of the cover 113 to be smaller than that of the core portion, and it is desirable for the dielectric constant to be equal to or smaller than that of the clad portion.

The size of the core and the cladding are determined under the condition that the reflection loss between the dielectric waveguide (hereinafter, unless otherwise specified, the first dielectric waveguide and the second dielectric waveguide are not distinguished from each other and are simply referred to as the dielectric waveguide) and the core is small. Since the relative dielectric constant of the dielectric waveguide and the relative dielectric constant of the core are the same or almost the same, it is desirable that the size of the core is approximately the same as the size of the dielectric waveguide. The size of the cladding is selected so that the influence of the guide part and the spring 115 on the components of the evanescent wave leaking into the cladding is sufficiently small, but for this purpose, the size of the cladding may be at most about half the size of the core. For example, the thickness of the guide part and the cover 113 is about 1 mm each. Therefore, the height of the first terminal 111 (the vertical length in FIG. 3) is at most about twice the size of the dielectric waveguide plus a few millimeters. If a core unit with a relative permittivity of 2.3 and a cross section of 3 mm x 6 mm designed for the 28 GHz band is used as the dielectric waveguide, the size of the first terminal 111 is about 14 mm at most, which is sufficiently smaller than that of a flanged metal waveguide. The higher the frequency of the electromagnetic wave propagating through the dielectric waveguide, the smaller the cross section size becomes, and the smaller the size of the connection structure 100 becomes. Furthermore, the longitudinal size of the connection structure 100 is generally determined by the longitudinal size of the first terminal 111 and the longitudinal size of the second terminal 121, so that the total size is about 10 mm. With a flanged metal waveguide, the length of the flange fixing screw is about 5 mm, and considering that the tapered length of the dielectric waveguide is about 5 mm to 20 mm, the total length of the connection structure 100 is shorter than the total length of the flanged metal waveguide. Therefore, the connection structure 100 is smaller and lighter than a flanged metal waveguide. Furthermore, with the connection structure 100, there is no need to tape the dielectric waveguide portion, and no flange processing is required, so the manufacturing costs are lower than with a flanged metal waveguide.

A specific example of the configuration of the above-mentioned connection structure 100 and its design method will be described. This example of the configuration is an application example to a 28 GHz band dielectric waveguide. Figure 5 shows the design parameters. A core unit with a rectangular cross section of 3 mm x 6 mm and a relative dielectric constant of 2.3 was used as the dielectric waveguide. The relative dielectric constant and cross-sectional size are only examples, and the size of the dielectric waveguide can be selected as desired as long as the shape allows electromagnetic waves of the desired frequency (28 GHz in this example) to propagate (i.e., the low-frequency cutoff frequency of the dielectric waveguide is 28 GHz or higher). However, in general, in order to reduce interference between modes that can propagate through the dielectric waveguide, it is often designed to have as few modes as possible. In this example, the dielectric waveguide is designed to satisfy the single mode condition of one propagation mode at 28 GHz. The relative dielectric constant of the core part of the connection structure 100 is the same as that of the dielectric waveguide, that is, 2.3. The relative dielectric constant of the cladding part is 1.5. The core width (W_core) and the clad width (W_clad) are parameters that greatly affect the transmission characteristics of the connection structure 100, and it is desirable to select values that minimize reflection and radiation at the boundary between the dielectric waveguide and the connection structure 100. The method of determining these parameters will be described. For simplicity, the spring 115 is assumed to be an ideal conductor, with a wire diameter of 0.5 mm and a longitudinal length of the spring 115 of 2 mm. For simplicity, the spring 115 and the clad are assumed to be in contact with each other (i.e., arranged with a gap of 0). For the guide portion and the cover 113, their influence on the characteristics of the connection structure 100 is small, so for simplicity, the relative dielectric constant is set to 1. In addition, the total length of the connection structure 100 (the longitudinal length when the first connector 110 and the second connector 120 are connected to each other) is set to 15 mm.

In the configuration shown in FIG. 5, in the dielectric waveguide, the core with a dielectric constant of 2.3 is surrounded by an air cladding with a low dielectric constant (dielectric constant of 1), so the relative refractive index difference is large and the propagation mode is tightly confined within the core (i.e., the leakage of evanescent waves is small). In the connection structure 100, the relative dielectric constant of the core is the same as that of the dielectric waveguide, and the relative dielectric constant of the cladding is 1.5, so the relative refractive index difference is small compared to the dielectric waveguide. Therefore, when the size of the core is the same as that of the dielectric waveguide, the mode propagating in the connection structure 100 takes a form in which the electromagnetic field spreads to a certain extent in the cladding (i.e., the leakage of evanescent waves is large). Therefore, the spot size of the propagation mode in the connection structure 100 is larger than the spot size of the propagation mode in the dielectric waveguide. It is known that when propagation modes with different spot sizes are connected to each other, reflection loss and radiation loss occur. For this reason, as shown in Figures 3 to 5, it is possible to make the size of the core portion of the connection structure 100 slightly larger than the size of the dielectric waveguide. This makes the mode propagating within the connection structure 100 more sensitive to the presence of the core portion, reducing the amount of evanescent waves leaking into the cladding portion, and making it possible to make the spot size of the mode propagating within the connection structure 100 approximately equal to the spot size of the propagation mode in the dielectric waveguide. This is shown in the following calculation.

For simplicity, W_clad is fixed at a sufficiently large value of 10 mm, and FIG. 6 shows the transmission characteristics (S21) of the connection structure 100 when W_core is changed in 1 mm steps from 2 mm to 6 mm. When the size of the core part is 3 mm, the same as the size of the dielectric waveguide, the loss is about 0.2 dB at 28-40 GHz. This is considered to be a sufficiently small value, but by making the size of the core part 4 mm, the loss can be reduced to about 0.1 dB. Furthermore, if the core diameter is reduced to 2 mm or increased to 6 mm, the loss increases. This shows that the spot size of the connection structure 100 changes depending on the size of the core part, and that there is a value (4 mm in this case) that matches the dielectric waveguide.

Next, a method for determining the size of the cladding portion will be described. It is desirable that the connection structure 100 be as small as possible, so the size of the cladding portion should be as small as possible. However, if it is too small, the electromagnetic waves propagating through the connection structure 100 are scattered due to the influence of the metal spring 115 on the electromagnetic field, resulting in increased loss in the connection structure 100. Therefore, it is sufficient to select the smallest possible cladding size among values where the influence of the spring 115 on the connection structure 100 can be ignored. Figure 7 shows the transmission characteristics of the connection structure 100 when the size of the core portion is 4 mm and the size of the cladding portion is changed in 0.5 mm steps from 0.5 mm to 5 mm. It can be seen that when the size of the cladding portion is too small, such as 0.5 mm, the loss of the connection structure 100 is large due to the influence of the spring 115. It can be seen that the loss is reduced as the size of the cladding portion is increased, and a low loss characteristic of about 0.1 dB can be achieved, as in the case shown in Figure 6. This is because the influence of the spring 115 is reduced as the size of the cladding portion is enlarged. Furthermore, there is almost no change in loss when the cladding size is 3 mm and when it is 5 mm. This means that with a cladding size of 3 mm or more, the spring 115 can be considered to be sufficiently far away from the path along which the electromagnetic waves propagate. Therefore, in this case, the cladding size can be 3 mm.

In the above example, the height of the connection structure 100 (the vertical size in FIG. 7) is 14 mm, assuming that the core portion is 4 mm in size, the cladding portion is 3 mm x 2, and the guide portion and cover 113 are a total of at most 4 mm. This is roughly half the size of a standard flanged metal waveguide, and it can be seen that it is significantly smaller than a flanged metal waveguide. Furthermore, since the connection structure 100 does not use a metal waveguide, it is naturally lightweight.

This configuration example is an example in which the cross-sectional size of the dielectric waveguide is 3 mm x 6 mm and the design frequency band is 28 GHz, but the same argument applies under other conditions, so the sizes of the core and clad portions that reduce the loss of the connection structure 100 can be determined by the above-mentioned process. Also, as can be seen from Figures 6 and 7, there are cases in which sufficiently small loss can be obtained without making the sizes of the core and clad portions different from those of the dielectric waveguide. In such cases, the sizes of the core and clad portions do not need to be different from those of the dielectric waveguide.

Second Embodiment
As the second embodiment, an improvement in the material of the core and/or clad will be described. Only the differences between the first and second embodiments will be described. For other technical matters, please refer to the description of the first embodiment.

In general, the smaller the dielectric constant of a dielectric, the smaller the high-frequency loss tends to be. Therefore, it is desirable to use a dielectric with as small a dielectric constant as possible as the material of the core portion, which is the main propagation portion of the electromagnetic wave. Furthermore, the dielectric constant of the cladding portion is required to be smaller than that of the core portion. However, in reality, it may be difficult to select a material with such a small dielectric constant in the millimeter wave band. From this perspective, in the second embodiment, as shown in FIG. 8, the first cladding 111b and the second cladding 121b are each foam. This example is not limited to this, and the first core 111a and the second core 121a, the first cladding 111b, and the second cladding 121b may each be foam.

A foam contains bubbles (whose relative dielectric constant is 1) at a certain density in a single dielectric material that is solid at room temperature, for example. Preferably, the bubbles are distributed as uniformly as possible in the foam. The relative dielectric constant of the foam is roughly the product of the relative dielectric constant of the dielectric material multiplied by the ratio of the dielectric volume to the volume of the foam (the sum of the dielectric volume and the bubble volume). Therefore, when a foam and a non-foam are manufactured using a dielectric material with a relative dielectric constant greater than 1, the relative dielectric constant of the foam is generally smaller than that of the non-foam. For example, a foam manufactured using a dielectric material with a relative dielectric constant of 2, in which 25% of the total volume is bubbles, has a relative dielectric constant of 1.5. In other words, a core and/or cladding with a relative dielectric constant of b (1<b<a) can be realized using a dielectric material with a relative dielectric constant of a (a>1).

Third Embodiment
When the first connector 110 and the second connector 120 are connected to each other, misalignment of the central axis of the first core 111a and the central axis of the second core a 121a causes reflection or radiation at the boundary (hereinafter referred to as the joint surface) between the first terminal surface 111s and the second terminal surface 121s that are in close contact with each other. As the third embodiment, an improved structure for precisely aligning the longitudinal central axis of the first core 111a and the frame-shaped end surface of the first cladding 111b with the longitudinal central axis of the second core 121a and the frame-shaped end surface of the second cladding 121b, respectively, will be described. Only the differences between the first embodiment and the third embodiment will be described. For other technical matters, please refer to the description of the first embodiment.

In the third embodiment, as shown in FIG. 9 and FIG. 10, one end of the first guide 111c in the longitudinal direction of the first guide 111c is located in front of the first terminal surface 111s, and one end of the second guide 121c in the longitudinal direction of the second guide 121c is located behind the second terminal surface 121s. Therefore, when the first connector 110 and the second connector 120 are connected to each other, the first terminal surface 111s and the second terminal surface 121s are guided toward each other by the two first guides 111c. When the first connector 110 and the second connector 120 are connected to each other, the joint surface is sandwiched between the two first guides 111c in a direction perpendicular to the longitudinal direction of the connection structure 100, and therefore, misalignment is unlikely to occur in a plane perpendicular to the longitudinal direction of the connection structure 100. According to the third embodiment, reflection or radiation at the joint surface is suppressed, and a low-loss connection structure 100 can be realized.

Not limited to the configuration shown in Figures 9 and 10, one end of the first guide 111c in the longitudinal direction of the first guide 111c may be located behind the first terminal surface 111s, and one end of the second guide 121c in the longitudinal direction of the second guide 121c may be located in front of the second terminal surface 121s.

Fourth Embodiment
The electromagnetic waves propagating through the dielectric waveguide and the electromagnetic waves reflected by the connection structure 100 form standing waves, which cause unnecessary ripples and the like to occur in the propagation characteristics of the electromagnetic wave propagation path including the connection structure 100. The electromagnetic waves reflected by the connection structure 100 are a cause of significant deterioration of the propagation characteristics of the propagation path. As the fourth embodiment, an improved structure for reducing the reflection of the electromagnetic waves in the connection structure 100 will be described. Only the differences between the first and fourth embodiments will be described. For other technical matters, please refer to the description of the first embodiment.

In the fourth embodiment, as shown in Figs. 11 and 12, the joint surface is not perpendicular to the propagation direction of the electromagnetic wave propagating through the dielectric waveguide, and the angle of incidence of the electromagnetic wave reflected at the joint surface with respect to the cladding is greater than the critical angle (in short, it is sufficient to say that the propagation direction of the electromagnetic wave propagating through the first terminal 111 is not perpendicular to the first terminal surface 111s, and the angle of incidence of the electromagnetic wave reflected at the first terminal surface 111s with respect to the first cladding 111b is greater than the critical angle). Even if reflection occurs at the joint surface, the cladding penetration angle of the reflected wave is greater than the cladding penetration angle (i.e., the critical angle) at which the reflected wave can propagate in the dielectric waveguide, so the reflected wave cannot propagate through the dielectric waveguide and is radiated. According to the fourth embodiment, although the transmission loss of the connection structure 100 cannot be improved, it is possible to prevent the electromagnetic wave reflected at the joint surface of the connection structure 100 from interfering with the electromagnetic wave propagating through the dielectric waveguide.

The technical features disclosed in the various embodiments described above are not necessarily mutually exclusive. Technical features of one embodiment may be applied to technical features of other embodiments, provided there is no contradiction from a technical point of view. In particular, according to the embodiments described above, embodiments having technical features disclosed in any two or more embodiments are also permissible.

<Applications and Modifications of the Embodiments>
(First Example)
As an application example of the first embodiment, a connection structure including a third connector and a fourth connector in addition to the first connector 110 and the second connector 120 will be described. In the connection structure illustrated in FIG. 13 and FIG. 14, the third connector has the same structure as the first connector 110, but is not limited to this example, and the fourth connector has the same structure as the second connector 120, but is not limited to this example. For this reason, using branch numbers to identify the connectors, the first connector is assigned a reference number 110-1, the second connector is assigned a reference number 120-2, the third connector is assigned a reference number 110-3, and the fourth connector is assigned a reference number 120-4. For the third connector 110-3, please refer to the description of the first connector 110 in the first embodiment. For the fourth connector 120-4, please refer to the description of the second connector 120 in the first embodiment. The names and symbols of the components of each of the connectors 110-1, 120-2, 110-3, and 120-4 are the names and symbols used in the description of the first embodiment with the above-mentioned subnumbers added thereto. For example, the "first core" included in the first connector 110-1 is the "first core 111a-1," and the "first core" included in the third connector 110-3 is the "first core 111a-3."

In the first example, unlike the first embodiment, the first core 111a-1 of the first connector 110-1 is connected at one of its two end faces, that is, at the other end of the first terminal 111-1, to one end of a third dielectric waveguide 930 different from the first dielectric waveguide 910 and the second dielectric waveguide 920, and the first core 111a-3 of the third connector 110-3 is connected at one of its two end faces, that is, at the other end of the first terminal 111-3, to the other end of the third dielectric waveguide 930. The structure of the third dielectric waveguide 930 is the same as that of the first dielectric waveguide 910 or the second dielectric waveguide 920, so please refer to the explanation of the first embodiment. The second core 121a-2 of the second connector 120-2 is connected to one end of the second dielectric waveguide 920 at the other end of the second terminal 121-2, and the second core 121a-4 of the fourth connector 120-4 is connected to one end of the first dielectric waveguide 910 at the other end of the second terminal 121-4. The first connector 110-1 is connected to the second connector 120-2, and the third connector 110-3 is connected to the fourth connector 120-4.

(Second Example)
In the second example, as shown in Figures 15 and 16, unlike the first example, the third dielectric waveguide 930 is not necessary, and the first core 111a-1 of the first connector 110-1 is connected to the first core 111a-3 of the third connector 110-3. In the second example, it is desirable that the first clad 111b-1 of the first connector 110-1 is connected to the first clad 111b-3 of the third connector 110-3. As shown in Figures 17 and 18, the first guide 111c-1 of the first connector 110-1 may be connected to the first guide 111c-3 of the third connector 110-3.

(Third Example)
In the third example, as shown in Figures 19 and 20, unlike the first and second examples, the second core 121a-2 of the second connector 120-2 is formed integrally with the second core 121a-4 of the fourth connector 120-4, the second clad 121b-2 of the second connector 120-2 is formed integrally with the second clad 121b-4 of the fourth connector 120-4, and the second guide 121c-2 of the second connector 120-2 is formed integrally with the second guide 121c-4 of the fourth connector 120-4. In this example, the second connector 120-2 and the fourth connector 120-4 are not separate tangible objects, but are constituent units of a single tangible object, and from this perspective, it can be said that the second core 121a-4 of the fourth connector 120-4 is the second core 121a-2 of the second connector 120-2 itself, the second clad 121b-4 of the fourth connector 120-4 is the second clad 121b-2 of the second connector 120-2 itself, and the second guide 121c-4 of the fourth connector 120-4 is the second guide 121c-2 of the second connector 120-2 itself. Of course, the present invention is not limited to this example, and may be a structure in which the second connector 120-2 and the fourth connector 120-4, which are separate tangible objects, are connected to each other, that is, the second core 121a-2 of the second connector 120-2 is connected to the second core 121a-4 of the fourth connector 120-4, the second clad 121b-2 of the second connector 120-2 is connected to the second clad 121b-4 of the fourth connector 120-4, and the second guide 121c-2 of the second connector 120-2 is connected to the second guide 121c-4 of the fourth connector 120-4 (the dashed line in FIG. 19 indicates the connection boundary). The first connector 110-1 is connected to the second connector 120-2, and the third connector 110-3 is connected to the fourth connector 120-4.

21 and 22, the second core 121a-2 of the second connector 120-2 may be connected to one end of a third dielectric waveguide 930 different from the first dielectric waveguide 910 and the second dielectric waveguide 920 at one of its two end faces, that is, at the other end of the second terminal 121-2, and the second core 121a-4 of the fourth connector 120-4 may be connected to the other end of the third dielectric waveguide 930 at one of its two end faces, that is, at the other end of the second terminal 121-4. In the example shown in FIGS. 21 and 22, the second core 121a-2 of the second connector 120-2 and the second core 121a-4 of the fourth connector 120-4 and the third dielectric waveguide 930 may be integrally formed. In this case, the second core 121a-2 of the second connector 120-2 and the second core 121a-4 and third dielectric waveguide 930 of the fourth connector 120-4 are not separate tangible objects, but are constituent units of a single tangible object. From this perspective, it can be said that the second core 121a-4 of the fourth connector 120-4 is the second core 121a-2 of the second connector 120-2 itself, and further, it can be said that the third dielectric waveguide 930 is the second core 121a-2 of the second connector 120-2 itself.

In the examples shown in Figures 13 to 22, the same type of connector is provided on both ends of the dielectric waveguide (first dielectric waveguide 910, second dielectric waveguide 920, third dielectric waveguide 930), so there is no need to be concerned about differences in connector types when connecting, making it easy to use.

The technical features of any of the above-described embodiments may be applied to the various application examples described above, provided there is no technical contradiction.

<Addendum>
While the invention has been described with reference to exemplary embodiments, those skilled in the art will recognize that various changes can be made and elements thereof substituted with equivalents without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular system, device, or component thereof to the teachings of the invention without departing from the essential scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Furthermore, the use of terms such as "first", "second", etc., if any, does not indicate a sequence or importance, and terms such as "first", "second", etc. are used to distinguish elements. The terms used herein are for the purpose of describing the embodiments and are not intended to limit the invention in any way. The term "comprises" and its conjugations, when used in this specification and/or the appended claims, discloses the presence of the mentioned features, steps, operations, elements, and/or components, but does not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The term "and/or" includes any and all combinations of one or more of the associated listed elements, if any. In the claims and the specification, unless otherwise stated, the terms "connected", "coupled", "joined", "connected", or synonyms thereof, and all forms thereof, do not necessarily negate the presence of one or more intermediate elements between two elements that are, for example, "connected" or "coupled" to each other or "connected" to each other. In the claims and the specification, the term "optional", if any, unless otherwise stated, should be understood as a term that represents the same meaning as the universal symbol ∀.

Unless otherwise specified, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant art and this disclosure, and should not be interpreted ideally or overly formally unless explicitly defined.

It will be understood that in describing the present invention, many techniques and steps are disclosed. Each of these has separate advantages and each can be used in combination with one or more, or in some cases all, of the other disclosed techniques. Thus, to avoid cluttering, this specification refrains from describing every possible combination of individual techniques or steps. Nevertheless, the specification and claims should be read with the understanding that such combinations are fully within the scope of the present invention and claims.

The corresponding structures, materials, acts, and equivalents of all functional elements combined with means or steps in the following claims are intended to include the structures, materials, or acts, if any, that perform the function in combination with other elements.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Various modifications and variations are permitted within the scope of the present invention. The selected and described embodiments are intended to illustrate the principles of the present invention and its practical application. The present invention can be used in various embodiments with various modifications and variations, which are determined according to the expected use. All such modifications and variations are intended to be included within the scope of the present invention as defined by the appended claims, and are intended to be accorded the same protection when interpreted in accordance with the breadth that is fairly, legally and equitably afforded.

Claims (9)

A connection structure for connecting two different dielectric waveguides to each other, comprising:
A first connector and a second connector are included.
The first connector includes a first terminal including a first core formed of a dielectric, a first clad formed of a dielectric, and a first guide formed of a dielectric, a cover formed of a dielectric, and a spring,
the second connector includes a second terminal including a second core formed of a dielectric, a second clad formed of a dielectric, and a second guide formed of a dielectric;
the first clad surrounds the first core and is in close contact with the first core,
the first guide is fixed to the first clad,
the spring is attached to the first terminal;
the cover is attached to the first terminal,
the first terminal has a first terminal surface at one end of the first terminal in a longitudinal direction of the first terminal, where the first core and the first clad are exposed,
the first guide and the cover have a spring holding mechanism that holds the spring between the first terminal and the cover and allows the cover to move in the longitudinal direction of the first terminal along the first guide by the elasticity of the spring;
the second clad surrounds the second core and is in close contact with the second core,
the second guide is fixed to the second clad;
the second terminal has a second terminal surface at one end of the second terminal in a longitudinal direction of the second terminal, where the second core and the second clad are exposed,
the cover and the second guide have a snap-fit mechanism for mechanically connecting to each other in a snap-fit manner;
the cover and the second guide move along the second guide and are mechanically connected to each other in a snap-fit manner, whereby the first connector and the second connector are connected to each other;
A dielectric waveguide connection structure in which, when the first connector and the second connector are connected to each other, the first terminal surface of the first terminal and the second terminal surface of the second terminal are pressed against each other by the elasticity of the spring. 2. The connection structure according to claim 1,
the two different dielectric waveguides are a first dielectric waveguide and a second dielectric waveguide,
the first core is connected to one end of the first dielectric waveguide at the other end of the first terminal, or the first core is one end of the first dielectric waveguide;
A connection structure, characterized in that the second core is connected to one end of the second dielectric waveguide at the other end of the second terminal, or the second core is one end of the second dielectric waveguide. The connection structure according to claim 2,
the first terminal has a size such that a spot size of a propagation mode of an electromagnetic wave propagating through the first dielectric waveguide and a spot size of a propagation mode of an electromagnetic wave propagating through the first terminal are equal to each other;
A connection structure characterized in that the second terminal has a size such that a spot size of a propagation mode of an electromagnetic wave propagating through the second dielectric waveguide and a spot size of a propagation mode of an electromagnetic wave propagating through the second terminal are equal to each other. In the connection structure according to any one of claims 1 to 2,
Each of the first core and the second core is a foam.
or
Each of the first cladding and the second cladding is a foam.
or
A connection structure, wherein the first core, the second core, the first clad and the second clad are each made of a foam. In the connection structure according to any one of claims 1 to 4,
the connection structure includes a guide that guides the first terminal surface and the second terminal surface toward each other when the first connector and the second connector are connected to each other;
A connection structure, wherein the guide is at least one of the first guide and the second guide. In the connection structure according to any one of claims 1 to 5,
a propagation direction of an electromagnetic wave propagating through the first terminal is not perpendicular to a surface of the first terminal,
A connection structure, characterized in that an incident angle of an electromagnetic wave reflected by said first terminal surface with respect to said first cladding is larger than a critical angle. In the connection structure according to any one of claims 1 to 6,
A connection structure, wherein the first guide and the cover have a limiting mechanism that limits a range within which the cover can move along the first guide in the longitudinal direction of the first terminal. 2. The connection structure according to claim 1,
Further, the connector includes a third connector and a fourth connector.
the third connector includes a third terminal including a third core formed of a dielectric, a third clad formed of a dielectric, and a third guide formed of a dielectric, a cover formed of a dielectric, and a spring;
the fourth connector includes a fourth terminal including a fourth core formed of a dielectric, a fourth clad formed of a dielectric, and a fourth guide formed of a dielectric;
the third clad surrounds the third core and is in close contact with the third core,
the third guide is fixed to the third cladding,
the spring of the third connector is attached to the third terminal;
the cover of the third connector is attached to the third terminal,
the third terminal has a third terminal surface at one end of the third terminal in a longitudinal direction of the third terminal, where the third core and the third clad are exposed,
the third guide and the cover of the third connector have a spring holding mechanism that holds the spring of the third connector between the third terminal and the cover of the third connector, and that allows the cover of the third connector to move in the longitudinal direction of the third terminal along the third guide by the elasticity of the spring of the third connector,
the fourth clad surrounds the fourth core and is in close contact with the fourth core,
the fourth guide is fixed to the fourth clad,
the fourth terminal has a fourth terminal surface at one end of the fourth terminal in a longitudinal direction of the fourth terminal, where the fourth core and the fourth clad are exposed,
the cover and the fourth guide of the third connector have a snap-fit mechanism for mechanically connecting to each other in a snap-fit manner;
the cover of the third connector moved along the fourth guide and the fourth guide are mechanically connected to each other in a snap-fit manner, whereby the third connector and the fourth connector are connected to each other;
when the third connector and the fourth connector are connected to each other, the third terminal surface of the third terminal and the fourth terminal surface of the fourth terminal are pressed against each other by the elasticity of the spring,
the two different dielectric waveguides are a first dielectric waveguide and a second dielectric waveguide,
the first core and the third core are connected to each other, or the first core is connected, at the other end of the first terminal, to one end of a third dielectric waveguide different from the first dielectric waveguide and the second dielectric waveguide, and the third core is connected, at the other end of the third terminal, to the other end of the third dielectric waveguide;
the second core is connected to one end of the second dielectric waveguide at the other end of the second terminal, or the second core is one end of the second dielectric waveguide;
A connection structure, characterized in that the fourth core is connected to one end of the first dielectric waveguide at the other end of the fourth terminal, or the fourth core is one end of the first dielectric waveguide. 2. The connection structure according to claim 1,
Further, the connector includes a third connector and a fourth connector.
the third connector includes a third terminal including a third core formed of a dielectric, a third clad formed of a dielectric, and a third guide formed of a dielectric, a cover formed of a dielectric, and a spring;
the fourth connector includes a fourth terminal including a fourth core formed of a dielectric, a fourth clad formed of a dielectric, and a fourth guide formed of a dielectric;
the third clad surrounds the third core and is in close contact with the third core,
the third guide is fixed to the third cladding,
the spring of the third connector is attached to the third terminal;
the cover of the third connector is attached to the third terminal,
the third terminal has a third terminal surface at one end of the third terminal in a longitudinal direction of the third terminal, where the third core and the third clad are exposed,
the third guide and the cover of the third connector have a spring holding mechanism that holds the spring of the third connector between the third terminal and the cover of the third connector, and that allows the cover of the third connector to move in the longitudinal direction of the third terminal along the third guide by the elasticity of the spring of the third connector,
the fourth clad surrounds the fourth core and is in close contact with the fourth core,
the fourth guide is fixed to the fourth clad,
the fourth terminal has a fourth terminal surface at one end of the fourth terminal in a longitudinal direction of the fourth terminal, where the fourth core and the fourth clad are exposed,
the cover and the fourth guide of the third connector have a snap-fit mechanism for mechanically connecting to each other in a snap-fit manner;
the cover of the third connector moved along the fourth guide and the fourth guide are mechanically connected to each other in a snap-fit manner, whereby the third connector and the fourth connector are connected to each other;
when the third connector and the fourth connector are connected to each other, the third terminal surface of the third terminal and the fourth terminal surface of the fourth terminal are pressed against each other by the elasticity of the spring,
the two different dielectric waveguides are a first dielectric waveguide and a second dielectric waveguide,
the second core and the fourth core are connected to each other, or the fourth core is the second core, or the second core is connected to one end of a third dielectric waveguide different from the first dielectric waveguide and the second dielectric waveguide at the other end of the second terminal, and the fourth core is connected to the other end of the third dielectric waveguide at the other end of the fourth terminal,
the first core is connected to one end of the first dielectric waveguide at the other end of the first terminal, or the first core is one end of the first dielectric waveguide;
A connection structure, characterized in that the third core is connected to one end of the second dielectric waveguide at the other end of the third terminal, or the third core is one end of the second dielectric waveguide.

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