Mode converter, mode conversion structure, transmission line

Abstract

To provide a mode conversion structure that reduces transmission loss and is suitable for miniaturization.SOLUTION: A mode conversion structure 100 includes a first waveguide 110 formed of a first dielectric and having one tapered end, the other tapered end, and a body, a cable-like second waveguide 120 formed of a second dielectric and having one end with an inversely tapered recess, and a tubular waveguide 130 having one open end and the other open end. One end of the first waveguide 110 is located inside the waveguide 130. The body of the first waveguide 110 closes one end of the waveguide 130. The other end of the first waveguide 110 fits into the recess of the second waveguide 120.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a mode conversion technique for converting the propagation mode of an electromagnetic wave between a dielectric waveguide and a waveguide. [Background technology]

[0002] Metallic waveguides are known as a transmission medium for high-frequency electromagnetic waves known as microwaves (including millimeter and quasi-millimeter waves). Metallic waveguides propagate electromagnetic waves through a cavity surrounded by metal. This allows for extremely low leakage of electromagnetic waves outside the metal waveguide, resulting in low propagation loss. In particular, in the millimeter-wave (30 GHz to 300 GHz) frequency band, metal waveguides have significantly lower propagation loss compared to coaxial lines, making them the primary transmission medium for millimeter waves. However, metal waveguides are also known to have unique difficulties in handling. Because the cavity is surrounded by metal, it is difficult to bend the metal waveguide freely. Therefore, it is difficult to install metal waveguides in narrow spaces such as indoors. Furthermore, metal waveguides have a high weight per unit length, making them unsuitable for long-distance transmission.

[0003] A dielectric waveguide is a wired transmission medium that does not use metal. A dielectric waveguide is made of a dielectric material and consists 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 tangible cladding. In a dielectric waveguide, the relative dielectric constant of the core is greater than that of the cladding. Therefore, the total reflection phenomenon confines electromagnetic waves to the core and its vicinity, which allows the formation of a mode in which electromagnetic waves propagate in the longitudinal direction of the dielectric waveguide, i.e., an electromagnetic wave propagation mode. Air (relative dielectric constant 1) is often used as the cladding.

[0004] The size of the cross section of a dielectric waveguide (i.e., the cross section perpendicular to the propagation direction of the electromagnetic wave) depends on the wavelength of the propagating electromagnetic wave. Because the cross section of a dielectric waveguide is small for millimeter waves, it is an easy-to-handle transmission medium. For example, if a dielectric waveguide that propagates a 28 GHz electromagnetic wave is constructed with a core with a relative dielectric constant of 2.3 and an air cladding, the cross section of the dielectric waveguide (which is assumed to be rectangular for simplicity) can be miniaturized to about 3 mm x 6 mm. Because a dielectric waveguide uses a dielectric material that is more flexible than metal, it is easier to bend than a metallic waveguide, and its weight per unit length is also smaller than that of a metallic waveguide. Therefore, it has the potential to solve the above-mentioned problems of a metallic waveguide.

[0005] FIG. 1 of Patent Document 1 discloses a connection structure for connecting two dielectric waveguides to each other. FIG. 1 shows a connection structure 800 disclosed in FIG. 1 of Patent Document 1. The connection structure 800 includes two mode conversion structures 800A and 800B, and has a structure in which the two mode conversion structures 800A and 800B are connected. The mode conversion structure 800X (X∈{A, B}) includes a square pipe-shaped metal waveguide 810X having a flange 810Xa formed at one end, and a cable-shaped dielectric waveguide 850X having a rectangular cross section except for one end. One end of the dielectric waveguide 850X is tapered and has a square right pyramid shape. One end of a dielectric waveguide 850X and the vicinity of that end (i.e., the vicinity of the dielectric waveguide 850X that is continuous with one end of the dielectric waveguide 850X and has a rectangular cross section) are attached to the other end of a metal waveguide 810X, and the rectangular right cone that is one end of the dielectric waveguide 850X and the vicinity of that end of the dielectric waveguide 850X are covered by the metal waveguide 810X. The vicinity of one end of the dielectric waveguide 850X is fitted tightly into the other end of the metal waveguide 810X. A flange 810Aa of one metal waveguide 810A and a flange 810Ba of the other metal waveguide 810B are fastened to each other with screws 830, and as a result, the two mode conversion structures 800A, 800B are connected to each other without any gaps or axial misalignment. The conversion of the propagation mode of the electromagnetic wave between the dielectric waveguide 850X and the metal waveguide 810X is achieved by the rectangular right pyramidal shape at one end of the dielectric waveguide 850X (see Non-Patent Document 1). The power loss of the electromagnetic wave due to this mode conversion is generally small. Therefore, the connection structure 800 can connect the two dielectric waveguides 850A and 850B to each other with low loss.

[0006] However, the connection structure 800 has a large loss between the dielectric waveguide 850X and the metal waveguide 810X. 21The design parameters are shown below. For simplicity, a square pipe-shaped metal waveguide 810X without a flange 810Xa was used in this simulation. The design parameters are as follows: The metal waveguide 810X corresponds to EIA (Electronic Industries Alliance) standard waveguide WR 34. The inner dimensions of the metal waveguide 810X (i.e., the size of the opening) are 4.318 mm high x 8.636 mm wide, and the length of the metal waveguide 810X is 60 mm. The height of the rectangular cone at one end of the dielectric waveguide 850X is 32.1 mm. The length of the portion of the dielectric waveguide 850X not covered by the metal waveguide 810X is 500 mm, and the length of the portion of the dielectric waveguide 850X covered by the metal waveguide 810X is 42.1 mm. Figure 2 shows that, for example, when the frequency of the electromagnetic wave is 28 GHz, a transmission loss of 4.6 dB occurs.

[0007] To reduce such transmission loss, a mode conversion structure 900 shown in Fig. 3 is known. The mode conversion structure 900 includes a cable-like dielectric waveguide 950 having a rectangular cross section except for one end, and a metal waveguide 910 having a shape in which a square pipe 911 is connected to one opening bottom (the smaller of the two opening bottoms, large and small) of a hollow square right pyramidal pipe 913. One end of the dielectric waveguide 950 is tapered, giving it the shape of a square right pyramid. One end of the dielectric waveguide 950 and the vicinity of that end (i.e., the vicinity of the dielectric waveguide 950 that is continuous with one end of the dielectric waveguide 950 and has a rectangular cross section) is attached to the boundary between the square pipe 911 and the hollow square right truncated pyramidal pipe 913 and an end portion located in the vicinity of that boundary of the square pipe 911 of the metal waveguide 910, and the square right truncated pyramidal portion that is one end of the dielectric waveguide 950 and the vicinity of that end of the dielectric waveguide 950 are covered by the square pipe 911 of the metal waveguide 910. The portion of the dielectric waveguide 950 in the vicinity of one end is fitted tightly into the square pipe 911 of the metal waveguide 910. Conversion of the propagation mode of the electromagnetic wave between the dielectric waveguide 950 and the metal waveguide 910 is achieved by the tapered shape of one end of the dielectric waveguide 950. A portion of the dielectric waveguide 950 that is continuous with the neighboring portion of the dielectric waveguide 950, is located near the neighboring portion, and has a rectangular cross section, is surrounded by a hollow square right frustum-shaped pipe 913.

[0008] FIG. 4 shows the transmission characteristics (S 21The design parameters are as follows: the square pipe 911 corresponds to EIA standard waveguide WR 34, and the internal dimensions of the square pipe 911 are 4.318 mm high x 8.636 mm wide, and the length of the square pipe 911 is 60 mm. The internal dimensions of the other opening bottom of the hollow square truncated right pyramidal pipe 913 (i.e., the size of the opening) are 21.4 mm high x 42.8 mm wide, and the height of the hollow square truncated right pyramidal pipe 913 is 40 mm. The height of the square pyramid at one end of the dielectric waveguide 950 is 32.1 mm, the length of the portion of the dielectric waveguide 950 not covered by the square pipe 911 is 500 mm, and the length of the portion of the dielectric waveguide 950 covered by the square pipe 911 is 42.1 mm. From Figure 4, it can be seen that, for example, when the frequency of the electromagnetic wave is 28 GHz, the transmission loss is reduced to about 0.2 dB. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2023-102939 [Non-patent literature]

[0010] [Non-Patent Document 1] GE 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. Summary of the Invention [Problem to be solved by the invention]

[0011] According to the mode conversion structure 900 shown in FIG. 3, although the insertion loss is reduced, the size of the hollow square right frustum-shaped pipe 913 is large, and therefore the size of the mode conversion structure is also large.

[0012] We disclose a mode conversion technology that reduces transmission loss and is suitable for miniaturization. [Means for solving the problem]

[0013] The technical matters described herein are not intended to explicitly or implicitly limit the invention described in the claims, nor to enable anyone other than those who benefit from the invention (e.g., the applicant and the right holder) to limit the invention described in the claims, but are provided merely to facilitate understanding of the gist of the invention. The outline of the invention from other perspectives can be understood, for example, from the claims at the time of filing of this patent application. The disclosed mode conversion structure includes a tubular waveguide and a cable-like dielectric waveguide. The dielectric waveguide is not one piece, but has a structure including two interconnected dielectric waveguides. Each end of one dielectric waveguide has a tapered shape. One end of the other dielectric waveguide has an inverse tapered shape. One end of one dielectric waveguide is located inside the waveguide, and one end of the waveguide is closed by the other dielectric waveguide. The other tapered end of one dielectric waveguide is located outside the waveguide and fits into the inverse tapered end of the other dielectric waveguide. It is desirable that the relative dielectric constant of one dielectric waveguide be greater than the relative dielectric constant of the other dielectric waveguide. The disclosed mode converter has a structure in which the other dielectric waveguide is removed from the above-mentioned mode conversion structure. The disclosed transmission line has a structure in which the above-mentioned mode converter is attached to each end of the other dielectric waveguide. [Effects of the Invention]

[0014] According to the present disclosure, a low-loss and compact mode converter, a low-loss and compact mode conversion structure, and a transmission line including a low-loss and compact mode conversion structure are realized. [Brief explanation of the drawings]

[0015] [Figure 1] Connection structure using flanged metal waveguide (prior art). [Figure 2] Pass characteristics of the connection structure shown in Figure 1. [Figure 3] Connection structure using horn antenna type metal waveguide (prior art). [Figure 4] Pass characteristics of the connection structure shown in Figure 3. [Figure 5] 1A and 1B are diagrams illustrating a mode converter and a mode conversion structure according to an embodiment, in which (a) is a cross-sectional view of a mode conversion structure including a mode converter, (b) is a cross-sectional view of a waveguide, (c) is a cross-sectional view of a first dielectric waveguide, and (d) is a cross-sectional view of a second dielectric waveguide. [Figure 6] 1A and 1B are cross-sectional views of modified examples of the first dielectric waveguide: (a) an example of an exponential taper, (b) an example of a parabolic taper, and (c) an example of a step taper. [Figure 7] Transmission characteristics of the mode conversion structure shown in Figure 5(a). [Figure 8] FIG. 2 is a cross-sectional view of a transmission line according to an embodiment. [Figure 9] 10A and 10B are cross-sectional views of modified mode conversion structures, respectively showing a mode conversion structure in an unconnected state and a mode conversion structure in a connected state; DETAILED DESCRIPTION OF THE INVENTION

[0016] The embodiments will be described with reference to the drawings. The drawings are not necessarily drawn to scale. The mode converter 200 of the embodiment includes a first dielectric waveguide 110 and a waveguide 130, and the mode conversion structure 100 of the embodiment includes the mode converter 200 and a second dielectric waveguide 120 (see FIG. 5(a)).

[0017] <Waveguide> The waveguide 130 is a tubular waveguide having one open end 130a and the other open end 130b (see FIG. 5(b)). A "tube" is a hollow structure having an internal cavity 130c that extends continuously in its longitudinal direction, with the cavity 130c communicating with the outside at both ends, and having an external shape in which the length is greater than the width. The waveguide 130 is typically made of metal. The waveguide 130 is typically a straight pipe due to the difficulty of metal processing, but is not limited to this. The waveguide 130 preferably has a uniform structure in which the shape, size, and material are constant at any position along the length of the waveguide 130. In the example shown in FIG. 5(b), the waveguide 130 is a tangible object having the shape of a square pipe. Waveguide 130 may have a flange (see FIG. 1) for connecting to another waveguide (not shown) if necessary, but waveguide 130 does not have a hollow rectangular truncated cone-shaped pipe (see FIG. 3) or a hollow truncated cone-shaped pipe. An EIA standard waveguide can be used as waveguide 130.

[0018] <First dielectric waveguide> The first dielectric waveguide 110 is a tangible object formed of a first dielectric. The first dielectric waveguide 110 does not have a cladding as a tangible object, but is a core itself as a tangible object. The first dielectric waveguide 110 has a uniform structure in which the material is constant at any position along the length of the first dielectric waveguide 110. The first dielectric waveguide 110 is a rod-shaped waveguide having one end 110a tapered in size toward the end, the other end 110b tapered in size toward the end, and a body 110c between the one end 110a and the other end 110b (see FIG. 5(c)). The tapered shape will be explained later. In the example shown in FIG. 5(c), the body 110c is a tangible object having a solid rectangular parallelepiped shape, and each of the one end 110a and the other end 110b of the first dielectric waveguide 110 has a square right pyramid shape. The shape and dimensions of one end face of the rectangular parallelepiped body 110c in the length direction of the first dielectric waveguide 110 (i.e., the propagation direction of the electromagnetic waves) match the shape and dimensions of the bottom face of one end 110a of the square right pyramid, and the shape and dimensions of the other end face of the rectangular parallelepiped body 110c in the length direction of the first dielectric waveguide 110 match the shape and dimensions of the bottom face of the other end 110b of the square right pyramid. The dimensions (i.e., height x width) of the cross section of the rectangular parallelepiped body 110c perpendicular to the length direction of the first dielectric waveguide 110 approximately match the inner dimensions (i.e., height x width of the opening) of the square pipe waveguide 130 perpendicular to the length direction of the waveguide 130.

[0019] <Mode converter> In the mode converter 200, the first dielectric waveguide 110 is attached to the waveguide 130. Specifically, one end 110a of the first dielectric waveguide 110 is located inside the waveguide 130, i.e., in a cavity 130c, and the body 110c of the first dielectric waveguide 110 completely closes the one end 130a of the waveguide 130 (see FIG. 5(a)). In this state, the one end 110a of the first dielectric waveguide 110 does not protrude from the other end 130b of the waveguide 130. Furthermore, in this state, preferably, the boundary between the body 110c of the first dielectric waveguide 110 and the other end 110b of the first dielectric waveguide 110 (see the dashed line on the right side of FIG. 5(c)) and the open end face of the one end 130a of the waveguide 130 are located on the same plane (see FIG. 5(a)). Therefore, the rectangular pyramid shape that is one end 110a of the first dielectric waveguide 110 and the body 110c of the first dielectric waveguide 110 are covered by the waveguide 130. The other end 110b of the first dielectric waveguide 110 is located outside the waveguide 130. Conversion of the propagation mode of the electromagnetic wave between the first dielectric waveguide 110 and the waveguide 130 is achieved by the rectangular pyramid shape that is one end 110a of the first dielectric waveguide 110.

[0020] <Second dielectric waveguide> The second dielectric waveguide 120 is a tangible object formed of a second dielectric. The relative permittivity of the first dielectric is greater than that of the second dielectric. The second dielectric waveguide 120 has an external shape in which the length is significantly greater than the width, like a cable (only the vicinity of one end 120a of the second dielectric waveguide 120 is shown in FIGS. 5(a) and 5(d)). The second dielectric waveguide 120 does not have a tangible cladding, but is a tangible core itself. The second dielectric waveguide 120 may have a linear shape or a meandering shape. The second dielectric waveguide 120 has a uniform structure in which the material is constant at any position in the length direction of the second dielectric waveguide 120 and the shape and size are constant at any position in the length direction of the second dielectric waveguide 120 except for the one end 120a. In the example shown in FIG. 5(d), the second dielectric waveguide 120 is a tangible object having the shape of an elongated solid rectangular parallelepiped except for one end 120a. The dimensions (i.e., height x width) of the cross section of the second dielectric waveguide 120, excluding the one end 120a, perpendicular to the longitudinal direction of the second dielectric waveguide 120, are the same as the dimensions (i.e., height x width) of the rectangular parallelepiped body 110c of the first dielectric waveguide 110, perpendicular to the longitudinal direction of the second dielectric waveguide 120. The one end 120a of the second dielectric waveguide 120 has an inversely tapered recess whose dimensions increase toward the end (see FIG. 5(d)). In this example, the shape of the recess at the one end 120a follows the shape of the other end 110b of the first dielectric waveguide 110. For example, if the other end 110b of the first dielectric waveguide 110 has a square right pyramid shape, the shape of the recess at the one end 120a is also a square right pyramid. However, as will be described later, it is not essential that the shape of the recess at one end 120a of the second dielectric waveguide 120 follow the shape of the other end 110b of the first dielectric waveguide 110.

[0021] <Mode conversion structure> In the mode conversion structure 100, the second dielectric waveguide 120 is attached to the first dielectric waveguide 110. Specifically, the other end 110b of the first dielectric waveguide 110 is fitted into a recess in one end 120a of the second dielectric waveguide 120 (see FIG. 5(a)). It is desirable that there be no gap between the other end 110b of the first dielectric waveguide 110 and one end 120a of the second dielectric waveguide 120. For example, an adhesive is used to tightly attach the other end 110b of the first dielectric waveguide 110 to the one end 120a of the second dielectric waveguide 120. It is desirable that the value of the relative dielectric constant of the adhesive be the same as or close to the relative dielectric constant of the first dielectric or the second dielectric to avoid deterioration of transmission characteristics due to the adhesive. Impedance matching between the first dielectric waveguide 110 and the second dielectric waveguide 120 is achieved by the tapered shape of one end 110a of the first dielectric waveguide 110 and the inversely tapered shape of one end 120a of the second dielectric waveguide 120, which fit tightly together.

[0022] When using an adhesive, it is not essential that the shape of the recess at one end 120a of the second dielectric waveguide 120 mirrors the shape of the other end 110b of the first dielectric waveguide 110, but the recess at one end 120a only needs to have a shape and dimensions that can accommodate the other end 110b of the first dielectric waveguide 110. This is because the adhesive can fill a gap between the other end 110b of the first dielectric waveguide 110 and the one end 120a of the second dielectric waveguide 120 due to a mismatch between their shapes.

[0023] In the mode conversion structure 100, an electromagnetic wave enters from the other end 130b of the waveguide 130 and propagates toward the other end of the second dielectric waveguide 120, or propagates from the other end of the second dielectric waveguide 120 toward the other end 130b of the incoming waveguide 130.

[0024] <Tapered shape> The tapered shapes of the one end 110a and the other end 110b of the first dielectric waveguide 110 are determined depending on the frequency of the electromagnetic wave, the relative dielectric constant of the first dielectric, the relative dielectric constant of the second dielectric, etc. The tapered shapes of the one end 110a and the other end 110b of the first dielectric waveguide 110 are not limited to a linear tapered shape (see FIG. 5(c)) in which the width decreases at a constant rate toward the end, but may be, for example, an exponential tapered shape (see FIG. 6(a)) in which the width decreases exponentially toward the end, a parabolic tapered shape (see FIG. 6(b)) in which the width decreases parabolically toward the end, or a stepwise tapered shape (see FIG. 6(c)) in which the width decreases stepwise toward the end.

[0025] <Modifications of the shapes of each component> The shape of the waveguide 130 is not limited to a square pipe, but may be, for example, a cylinder or an elliptical cylinder. In this case, the body 110c of the first dielectric waveguide 110 is a tangible object having the shape of a solid circular cylinder or a solid elliptical cylinder. When the body 110c is, for example, a solid circular cylinder, each of the one end 110a and the other end 110b of the first dielectric waveguide 110 has a tapered shape of a right circular cone, and the width (i.e., diameter) of the cylindrical body 110c, the dimension of the base (i.e., diameter) of the one end 110a of the right circular cone, and the dimension of the base (i.e., diameter) of the other end 110b of the right circular cone are consistent with each other. Furthermore, in this case, the second dielectric waveguide 120 is a tangible object having the shape of an elongated solid circular cylinder or an elongated solid elliptical cylinder.

[0026] FIG. 7 shows the transmission characteristics (S 21The design parameters are as follows: The waveguide 130 corresponds to EIA standard waveguide WR 34, and its internal dimensions are 4.318 mm high x 8.636 mm wide, and its length is 60 mm. The height of the rectangular cone at one end 110a of the first dielectric waveguide 110 is 32.1 mm, and the length of the portion of the first dielectric waveguide 110 covered by the waveguide 130 is 42.1 mm. The length of the second dielectric waveguide 120 is 500 mm. The relative dielectric constant of the first dielectric is 6, and the relative dielectric constant of the second dielectric is 2.1. From Figure 7, it can be seen that, for example, when the frequency of the electromagnetic wave is 28 GHz, the transmission loss is approximately 0.7 dB.

[0027] <Transmission line> FIG. 8 shows a transmission line 300 according to an embodiment. The transmission line 300 has a structure in which a mode converter 200 is attached to one end of a second dielectric waveguide 120, and a mode converter 200' is attached to the other end of the second dielectric waveguide 120. The structure and function of the mode converter 200' are substantially the same as those of the mode converter 200, and therefore, the components of the mode converter 200' corresponding to those of the mode converter 200 are denoted with "'" and their descriptions are omitted. The other end of the second dielectric waveguide 120 also has a recessed portion with an inverse tapered shape whose dimensions increase toward the end (see FIG. 8). In this example, the shape of the recessed portion at the other end of the second dielectric waveguide 120 follows the shape of the other end of the first dielectric waveguide included in the mode converter 200'. The shape of the first dielectric waveguide and / or waveguide included in the mode converter 200′ may be the same as or different from the shape of the first dielectric waveguide and / or waveguide included in the mode converter 200. The dimensions of the first dielectric waveguide and / or waveguide included in the mode converter 200′ may be the same as or different from the dimensions of the first dielectric waveguide and / or waveguide included in the mode converter 200. The relative dielectric constant of the first dielectric waveguide included in the mode converter 200′ may be the same as or different from the relative dielectric constant of the first dielectric waveguide included in the mode converter 200. However, it is desirable that the relative dielectric constant of the first dielectric waveguide included in the mode converter 200 is larger than the relative dielectric constant of the second dielectric waveguide 120, and that the relative dielectric constant of the first dielectric waveguide included in the mode converter 200′ is larger than the relative dielectric constant of the second dielectric waveguide 120.

[0028] <Modification 1 of mode conversion structure> To prevent the first dielectric waveguide 110 from escaping from the waveguide 130, a mechanical connection structure between the waveguide 130 and the first dielectric waveguide 110 may be employed. In this mechanical connection structure, the body 110c of the first dielectric waveguide 110 has a threaded hole, and the waveguide 130 has a through-hole. When the body 110c of the first dielectric waveguide 110 tightly seals one end 130a of the waveguide 130 as described above, the through-hole of the waveguide 130 is positioned above the threaded hole of the body 110c. Therefore, a screw 50 can be inserted through the through-hole of the waveguide 130 into the threaded hole of the body 110c (see FIG. 9 ). In other words, the waveguide 130 is screwed to the first dielectric waveguide 110 with the screw 50. The screw 50 is made of a dielectric material, and is preferably a composite made of two different types of dielectric material. The portion of the screw 50 that is embedded in the first dielectric waveguide 110 is made of a first dielectric, and the portion of the screw 50 that is not embedded in the first dielectric waveguide 110 is made of a third dielectric that is different from the first dielectric. The relative dielectric constant of the third dielectric is preferably smaller than that of the first dielectric. Dielectric grease may be applied to the thread grooves to prevent gaps between the screw 50 and the first dielectric waveguide 110. The dielectric grease preferably has a relative dielectric constant that is the same as or close to that of the first dielectric.

[0029] <Modification 2 of mode conversion structure> A mechanical connection structure may be adopted instead of adhesive to tightly connect the other end 110b of the first dielectric waveguide 110 and the one end 120a of the second dielectric waveguide 120. This structure includes a cover 70 made of a dielectric material.

[0030] The cover 70 includes one main body 70a and two arm portions 70b. The main body 70a has a square pipe shape following the shape of the waveguide 130, and has a rectangular parallelepiped internal space extending in the longitudinal direction of the cover 70 (however, the longitudinal direction of the cover 70 is parallel to the propagation direction of the electromagnetic waves). Specifically, the main body 70a is composed of four rectangular flat plate-shaped side walls, two relatively larger of the four side walls being two large side walls parallel to each other in a first direction perpendicular to the longitudinal direction of the cover 70, and two relatively smaller of the four side walls being two small side walls parallel to each other in a second direction perpendicular to both the longitudinal direction of the cover 70 and the first direction.

[0031] One of the two arms 70b extends in the longitudinal direction of the cover 70 from one end of one of the two large side walls of the main body 70a in the longitudinal direction of the cover 70, with the outer wall surface of one large side wall continuing seamlessly with the outer wall surface of one arm 70b. The other of the two arms 70b extends in the longitudinal direction of the cover 70 from one end of the other of the two large side walls of the main body 70a in the longitudinal direction of the cover 70, with the outer wall surface of the other large side wall continuing seamlessly with the outer wall surface of the other arm 70b. In this example, the one main body 70a and the two arms 70b are integrally formed. The two arms 70b have the same shape, specifically, a rectangular plate shape extending in the longitudinal direction of the cover 70. At one end of the arm 70b, a protrusion 70d protrudes perpendicularly inward from the arm 70b.

[0032] The cover 70 is attached to the waveguide 130 (see FIG. 9). The cover 70 is attached to the waveguide 130 by passing the other end 130b of the waveguide 130, to which the first dielectric waveguide 110 is attached, between the two arms 70b of the cover 70 and through the internal space of the main body 70a, in that order. In the example shown in FIG. 9, the main body 70a of the cover 70 is located on the side closer to the other end 130b of the waveguide 130 with respect to the screw 50, and the protrusion 70d of the cover 70 is located on the side closer to the one end 130a of the waveguide 130 with respect to the screw 50. The cover 70 can slide along the waveguide 130, and the sliding of the cover 70 toward the one end 130a of the waveguide 130 is stopped by the inner end surface of the main body 70a of the cover 70 coming into contact with the head of the screw 50.

[0033] The second dielectric waveguide 120 has two long side surfaces parallel to each other in a third direction orthogonal to the longitudinal direction of the second dielectric waveguide 120, and two short side surfaces parallel to each other in a fourth direction orthogonal to both the longitudinal direction and the third direction of the second dielectric waveguide 120 (typically, 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). The long side surfaces are sides whose width (i.e., the length in the third direction) is equal to the length of the long side of the rectangular end face, and the short side surfaces are sides whose width (i.e., the length in the fourth direction) is equal to the length of the short side of the rectangular end face. The second dielectric waveguide 120 has a recess 120d on the long side surface of the second dielectric waveguide 120 near one end 120a of the second dielectric waveguide 120.

[0034] Next, the connection between the mode converter 200 having the above-described mechanical connection structure and the second dielectric waveguide 120 will be described. With the other end 110b of the first dielectric waveguide 110 and one end 120a of the second dielectric waveguide 120 facing each other (see FIG. 9(a)), a user manually pushes one end 120a of the second dielectric waveguide 120 between the two arms 70b of the cover 70, which have been spread apart. The other end 120b of the first dielectric waveguide 110 is fitted into one end 120a of the second dielectric waveguide 120, and the cover 70 is slid toward the second dielectric waveguide 120. As a result, the protrusion 70d of the cover 70 engages with the recess 120d of the second dielectric waveguide 120 due to the elasticity of the arms 70b of the cover 70, i.e., in a snap-fit manner. With the other end 120b of the first dielectric waveguide 110 fitted into one end 120a of the second dielectric waveguide 120 and the convex portion 70d of the cover 70 engaged with the concave portion 120d of the second dielectric waveguide 120, the inner end surface of the main body portion 70a of the cover 70 is in contact with the head of the screw 50 (see FIG. 9(b)). Therefore, movement of the second dielectric waveguide 120 in its longitudinal direction is prevented. In this configuration, if a gap occurs between the other end 120b of the first dielectric waveguide 110 and one end 120a of the second dielectric waveguide 120, this gap may be filled with non-adhesive dielectric grease or powder of the first or second dielectric.

[0035] The cover 70 is made of a dielectric, preferably a composite made of two different types of dielectric. The buried portion of the protrusion 70d of the cover 70 that is buried in the recess 120d is made of a second dielectric, and the portion of the cover 70 excluding the buried portion is made of a fourth dielectric that is different from the second dielectric. The relative dielectric constant of the fourth dielectric is preferably smaller than that of the second dielectric. Dielectric grease may be applied to the recess 120d to prevent a gap between the cover 70 and the second dielectric waveguide 120. The dielectric grease preferably has a relative dielectric constant that is the same as or close to that of the second dielectric.

[0036] Unless there is a contradiction from a technical viewpoint, the technical features of any of the above-described embodiments may be applied to the above-described various application examples.

[0037] <Addendum> While the present invention has been described with reference to exemplary embodiments, those skilled in the art will recognize that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the invention. Furthermore, many modifications can be made to adapt a particular system, device, or component thereof to the teachings of the present 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 rather that the invention will include all embodiments falling within the scope of the appended claims.

[0038] Furthermore, the use of terms such as "first," "second," etc., when used in this specification and / or the appended claims, does not denote any order or importance, and terms such as "first," "second," etc., are used to distinguish between elements. The terms used herein are for the purpose of describing 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, reveal the presence of referenced features, steps, operations, elements, and / or components, but do 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 specified, the use of words such as "connected," "coupled," "joined," "connected," or synonyms thereof, and all word forms thereof, does not necessarily negate the presence of one or more intermediate elements between two elements, e.g., "connected" or "coupled" to each other or "connected" to each other. In the claims and the specification, the term "any," if any, should be understood as a term that has the same meaning as the universal symbol ∀, unless otherwise specified. For example, the phrase "for any X" has the same meaning as "for all X" or "for each X." A phrase such as "at least one of A, B, and C" (e.g., "at least one of A, B, and C," "at least one of A, B, or C," "at least one of A, B, and / or C"), if any, should be understood as a term that has the same meaning as the universal symbol ∀, unless otherwise specified. S This means that we arbitrarily select one element from the set P excluding the empty set φ. In this example, S={A,B,C},2 S={φ,{A},{B},{C},{A,B},{A,C},{B,C},{A,B,C}},P={{A},{B},{C},{A,B},{A,C},{B,C},{A,B,C}}, which means that one element (e.g., {A,C}) is arbitrarily selected from the set P.

[0039] Unless otherwise specified, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill 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 excessively formally unless explicitly defined.

[0040] It will be understood that in describing the present invention, many techniques and steps are disclosed. Each of these has distinct advantages, and each can be used in combination with one or more, or in some cases all, of the other disclosed techniques. Therefore, to avoid cluttering, this specification will refrain 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.

[0041] The corresponding structure, material, acts, and equivalents of all functional elements combined with means or steps in the following claims are intended to include the structure, material, or acts, if any, that perform the function in combination with other elements.

[0042] Although the present invention has been described above with reference to exemplary embodiments, it is not limited to these embodiments. Various modifications and variations are possible without departing from the spirit 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 may 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 to be given. [Explanation of symbols]

[0043] 50 screws 70 Cover 70a Main body 70b Arm 70d convex part 100 Mode conversion structure 110 Dielectric Waveguide 110a one end 110b other end 110c fuselage 120 Dielectric Waveguide 120a one end 120b other end 120d recess 130 Waveguide 130a one end 130b other end 130c hollow 200 Mode Converter 300 Transmission Line 800 Connection Structure 830 screws 800A mode conversion structure 800B mode conversion structure 810A Metallic Waveguide 810B Metal Waveguide 850A Dielectric Waveguide 850B Dielectric Waveguide 810Aa flange 810Ba flange 900 mode conversion structure 910 Metal waveguide 911 Square Pipe 913 Straight truncated cone pipe 950 Dielectric Waveguide

Claims

1. A mode converter, a rod-shaped waveguide formed of a dielectric material and having a tapered end, a tapered other end, and a body between the one end and the other end; A tubular waveguide with one open end and the other open end Including, the one end of the waveguide is located inside the waveguide; the body of the waveguide closes the one end of the waveguide; The other end of the waveguide is located outside the waveguide. Mode converter.

2. A mode converting structure, a rod-shaped first waveguide formed of a first dielectric material and having a tapered end, a tapered other end, and a body between the one end and the other end; a cable-like second waveguide formed of a second dielectric material and having one end with an inversely tapered recess; A tubular waveguide with one open end and the other open end Including, the one end of the first waveguide is located inside the waveguide; the body of the first waveguide closes the one end of the waveguide; The other end of the first waveguide is fitted into the recess of the second waveguide. Mode conversion structure.

3. 3. The mode converting structure according to claim 2, The relative dielectric constant of the first dielectric is greater than the relative dielectric constant of the second dielectric. A mode conversion structure characterized by:

4. A transmission line comprising: a first mode converter; a second mode converter; and a cable-like first waveguide formed of a first dielectric and having one end with an inversely tapered recess and the other end with an inversely tapered recess; Including, The first mode converter comprises: a rod-shaped second waveguide formed of a second dielectric material and having a tapered end, a tapered other end, and a body between the one end and the other end; a tubular first waveguide having one open end and another open end; Including, The second mode converter comprises: a rod-shaped third waveguide formed of a third dielectric material and having a tapered end, a tapered other end, and a body between the one end and the other end; a tubular second waveguide having one open end and the other open end; Including, the one end of the second waveguide is located inside the first waveguide; the body of the second waveguide closes the one end of the first waveguide; the one end of the third waveguide is located inside the second waveguide; the body of the third waveguide closes the one end of the second waveguide; the other end of the second waveguide is fitted into the recess at the one end of the first waveguide, The other end of the third waveguide is fitted into the recess in the other end of the first waveguide. Transmission line.

5. 5. The transmission line according to claim 4, the second dielectric has a higher dielectric constant than the first dielectric; The third dielectric has a higher dielectric constant than the first dielectric. A transmission line characterized by:

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