Connection structure between dielectric waveguide and waveguide

Abstract

A connecting means is provided that has a simple structure, which can suppress deterioration in the transmission characteristics of radio waves and can reliably fix a dielectric waveguide and a waveguide together. [Solution] The device comprises a dielectric waveguide (100) having an inner layer and an outer layer with different dielectric constants, a cylindrical waveguide (200) into which at least a portion of the dielectric waveguide (100) can be inserted, and a pin (300) that penetrates the waveguide (200) and the dielectric waveguide (100) and is configured to suppress transmission loss due to reflected waves at the portion where the dielectric waveguide (100) is inserted into the waveguide (200).

Description

[Technical Field]

[0001] The present invention relates to a connection structure between a dielectric waveguide and a waveguide. [Background technology]

[0002] Radio wave transmission media include coaxial cables, dielectric waveguides, waveguides, etc. Depending on the installation mode of the equipment, different types of transmission media may be connected and used.

[0003] Patent Document 1 discloses a connector-equipped dielectric waveguide line comprising a dielectric waveguide line and a connector, wherein the dielectric waveguide line is composed of a dielectric waveguide line main body and a dielectric waveguide line end portion, the cross-sectional area of ​​the dielectric waveguide line end portion is smaller than the cross-sectional area of ​​the dielectric waveguide line main body, the connector is configured to be connectable to a mating member, and comprises a connecting portion that slidably holds the dielectric waveguide line main body, and a fixing portion that is connected to the connecting portion so as to be able to advance and retreat and is fixed to the dielectric waveguide line main body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018-216636 Summary of the Invention [Problem to be solved by the invention]

[0005] At the connection point between the dielectric waveguide and the waveguide, it is necessary to reliably fix the dielectric waveguide and the waveguide.

[0006] An object of the present invention is to provide a connecting means that can reliably fix a dielectric waveguide and a waveguide with a simple structure. [Means for solving the problem]

[0007] The present invention, which achieves the above object, provides a connection structure between a dielectric waveguide and a waveguide, comprising: a dielectric waveguide having an inner layer and an outer layer with different dielectric constants; a cylindrical waveguide into which at least a portion of the dielectric waveguide can be inserted; and a pin that penetrates the waveguide and the dielectric waveguide at a portion where the dielectric waveguide is inserted into the waveguide. More specifically, the pin may be provided so as to be oriented perpendicular to the electric field caused by the radio waves transmitted through the dielectric waveguide and the waveguide. Furthermore, two of the pins may be arranged side by side along the length direction of the dielectric waveguide and the waveguide. More specifically, the interval between the two pins may be set to about 1 / 4 or about 3 / 4 of the guide wavelength of the radio waves transmitted through the waveguide. The dielectric waveguide may also be configured so that the end portion inserted into the waveguide has a tapered shape with a diameter gradually decreasing toward the tip. The waveguide may have a tapered end, into which the dielectric waveguide is inserted, with the diameter gradually increasing towards the tip. [Effects of the Invention]

[0008] According to the present invention, the dielectric waveguide and the waveguide can be reliably fixed with a simple structure. [Brief explanation of the drawings]

[0009] [Figure 1] 1A and 1B are diagrams illustrating an example of the configuration of a connection portion between a dielectric waveguide and a waveguide to which the present embodiment is applied. [Figure 2] 2 is a side view of the connection point shown in FIG. 1 as seen in a direction along the pin insertion direction. [Figure 3] 2 is a side view of the connection point shown in FIG. 1, viewed in a direction perpendicular to the pin insertion direction. [Figure 4] FIG. 2 is a diagram showing a cross section along the length direction of a dielectric waveguide. [Figure 5] FIG. 2 is a diagram showing a cross section along the length of a waveguide. [Figure 6] 6A and 6B are diagrams showing the transmission characteristics of a dielectric waveguide and a waveguide, where FIG. 6A shows the reflection characteristics and FIG. 6B shows the transmission characteristics. [Figure 7] 7A and 7B are diagrams showing changes in transmission characteristics depending on the distance between two pins, with FIG. 7A showing reflection characteristics and FIG. 7B showing transmission characteristics. [Figure 8] FIG. 10 is a diagram showing the reflection characteristics of a pin when the pin is configured not to come into direct contact with the outer peripheral surface of the waveguide. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. <Overall structure> FIG. 1 is a diagram showing an example of the configuration of a connection point between a dielectric waveguide and a waveguide to which this embodiment is applied. The dielectric waveguide 100 is a linear member made of a dielectric material and has a circular cross section. The waveguide 200 is a cylindrical member made of metal. FIG. 2 is a side view of the connection point shown in FIG. 1 as seen in a direction along the insertion direction of the pin 300. FIG. 3 is a side view of the connection point shown in FIG. 1 as seen in a direction perpendicular to the insertion direction of the pin 300. In FIGS. 2 and 3, the portion of the dielectric waveguide 100 inserted into the waveguide 200 is drawn with a dashed line in a see-through manner.

[0011] 2 and 3, the tip of the dielectric waveguide 100 is inserted into a cylindrical waveguide 200. This connects the dielectric waveguide 100 and the waveguide 200. That is, the radio waves transmitted by the dielectric waveguide 100 are transmitted to the waveguide 200 via the connection point shown in Fig. 1. In this embodiment, the frequency band of the radio waves transmitted through the dielectric waveguide 100 and the waveguide 200 is assumed to be the millimeter wave band (a frequency band of 30 GHz to 300 GHz).

[0012] 1 to 3, a pin 300 is inserted into the side surface of the waveguide 200. As shown in FIGS. 2 and 3, the pin 300 penetrates the waveguide 200 and the dielectric waveguide 100 at a position where the dielectric waveguide 100 inserted into the waveguide 200 exists. More specifically, the pin 300 is inserted from the outer side surface of the waveguide 200 toward the inside, penetrates the dielectric waveguide 100, and protrudes from the outer side surface on the opposite side of the waveguide 200. The tip of the pin 300 protruding from the waveguide 200 is bent so that it does not come out of the waveguide 200 and the dielectric waveguide 100. In this way, the dielectric waveguide 100 is fixed in place while inserted into the waveguide 200. Furthermore, the outer peripheral surface of the waveguide 200 may be covered with an insulator (such as rubber or resin) for protection, so that the pin 300 does not come into direct contact with the outer peripheral surface of the waveguide 200. Details of the connection point between the dielectric waveguide 100 and the waveguide 200 will be described later.

[0013] <Configuration of Dielectric Waveguide 100> FIG. 4 is a diagram showing a cross section of the dielectric waveguide 100 along its length. FIG. 4 shows a cross section of the dielectric waveguide 100 near its tip, which is inserted into the waveguide 200. The dielectric waveguide 100 includes an inner layer portion 110 and an outer layer portion 120. The inner layer portion 110 is the core of the dielectric waveguide 100, and the outer layer portion 120 is the cladding of the dielectric waveguide 100. The inner layer portion 110 is formed of a linear dielectric. The outer layer portion 120 is formed of a dielectric having a smaller dielectric constant than the inner layer portion 110 and covers the outer periphery of the inner layer portion 110. This gives the dielectric waveguide 100 a two-layer structure consisting of the inner layer portion 110 and the outer layer portion 120. Although not shown, a protective film may be provided to cover the outer periphery of the outer layer portion 120. The protective film may be formed of, for example, an olefin-based shrink tube.

[0014] The inner layer portion 110 may be formed using, for example, a fluororesin. More specifically, for example, PTFE (polytetrafluoroethylene) may be used. The outer layer portion 120 may be formed using, for example, a fluororesin. More specifically, for example, expanded PTFE (ePTFE) may be used. The inner layer portion 110 is made of a material having a higher relative dielectric constant than the outer layer portion 120. As a result, radio waves propagating through the inner layer portion 110 are reflected at the boundary between the inner layer portion 110 and the outer layer portion 120. For this reason, in the dielectric waveguide 100, radio waves are propagated mainly in the inner layer portion 110.

[0015] The cross-sectional shapes of the inner layer portion 110 and the outer layer portion 120 perpendicular to the longitudinal direction are, for example, circular. More specifically, the cross-section of the inner layer portion 110 is circular, and the cross-section of the outer layer portion 120 is annular with an inner diameter equal to the outer diameter of the inner layer portion 110. The radius of the inner layer portion 110 is selected depending on the frequency of the propagating radio waves, etc. For example, the diameter of the inner layer portion 110 may be 3.3 mm in a dielectric waveguide 100 that propagates radio waves of 60 GHz, and 6.5 mm in a dielectric waveguide 100 that propagates radio waves of 28 GHz.

[0016] As shown in Fig. 4, the end of the dielectric waveguide 100 has a generally tapered shape with a diameter that decreases toward the tip. To explain the shape of the end of the dielectric waveguide 100 in more detail, it is composed of a tapered first tapered section 101 from the tip side, a thin shaft section 102 that extends with the same thickness (thin diameter), a tapered second tapered section 103, and a thick shaft section 104 that extends with the same thickness (thick diameter). In other words, the end of the dielectric waveguide 100 shown in Fig. 4 has a generally two-step tapered shape (first tapered section 101 and second tapered section 103) as a whole.

[0017] 4, the first tapered portion 101 and the thin shaft portion 102 are composed only of the inner layer portion 110. The second tapered portion 103 and the thick shaft portion 104 are composed of the inner layer portion 110 and the outer layer portion 120. In other words, the end of the dielectric waveguide 100 is configured such that the inner layer portion 110, in which the thin shaft portion 102 and the first tapered portion 101 are formed, is exposed at the tip of the second tapered portion 103. As shown in FIG. 4, the thin shaft portion 102 has a through hole 111 formed therein, into which the pin 300 is inserted.

[0018] Note that the shape shown in FIG. 4 is merely one example of the shape of the end of the dielectric waveguide 100. The end of the dielectric waveguide 100 may have a shape different from the example shown in FIG. 4 depending on the relationship between the size of the dielectric waveguide 100 and the size of the waveguide 200 and the shape of the end of the waveguide 200, as long as it has a tapered shape overall. For example, the first tapered portion 101 may be omitted, and the end may be composed of a thin shaft portion 102 with a flat tip, a second tapered portion 103, and a thick shaft portion 104. Alternatively, the thin shaft portion 102 may be omitted, and a tapered shape continuing from the first tapered portion 101 to the second tapered portion 103 may be formed. In this case, the through hole 111 is provided at an appropriate position in the portion where the inclined surface connects the first tapered portion 101 to the second tapered portion 103. 4, the thin shaft portion 102 is composed of only the inner layer portion 110, but the thin shaft portion 102 may also be configured such that the inner layer portion 110 is covered by an outer layer portion 120 that is thinner than the thick shaft portion 104. In this case, the through-hole 111 is provided so as to penetrate the outer layer portion 120 and the inner layer portion 110.

[0019] <Configuration of the Waveguide 200> FIG. 5 is a diagram showing a cross section of the waveguide 200 along its length. FIG. 5 shows a cross section of the waveguide 200 around the end where the dielectric waveguide 100 is inserted. The waveguide 200 is a hollow cylindrical member made of metal. The waveguide 200 is made of brass, bronze, copper, silver, aluminum, or the like. The cross-sectional shape of the waveguide 200 perpendicular to its length is not particularly limited, and may be, for example, an annular shape (circular waveguide) or a rectangular ring-shaped shape (rectangular waveguide). As an example, the waveguide 200 may have an annular shape whose inner diameter is approximately the same as that of the thin shaft portion 102 of the dielectric waveguide 100.

[0020] 5, the end of waveguide 200 has an inverse tapered shape in which the diameter increases toward the tip. Hereinafter, this inverse tapered portion will be referred to as inverse tapered portion 220. Furthermore, the portion of waveguide 200 other than inverse tapered portion 220 may be referred to as main body portion 210 to distinguish it from inverse tapered portion 220.

[0021] The inclination of the inner wall of the inverted tapered portion 220 is approximately the same as the inclination of the second tapered portion 103 of the dielectric waveguide 100. Therefore, when the dielectric waveguide 100 is inserted into the waveguide 200, the inner wall of the inverted tapered portion 220 of the waveguide 200 and the side surface of the second tapered portion 103 of the dielectric waveguide 100 face each other and come into contact with each other.

[0022] 5, a through hole 211 into which the pin 300 is inserted is formed in the main body 210 of the waveguide 200. The through hole 211 is provided in the main body 210 at a position corresponding to the through hole 111 provided in the dielectric waveguide 100 when the dielectric waveguide 100 is inserted in the waveguide 200.

[0023] <Connection configuration> Next, the configuration of the connection portion between the dielectric waveguide 100 and the waveguide 200 will be further described. As explained with reference to Fig. 4, the end of the dielectric waveguide 100 that is inserted into the waveguide 200 has a substantially tapered shape. On the other hand, as explained with reference to Fig. 5, the end of the waveguide 200 that the dielectric waveguide 100 is inserted into has an inversely tapered shape. Therefore, when the dielectric waveguide 100 is inserted into the waveguide 200, the tip of the dielectric waveguide 100 is easily guided into the waveguide 200.

[0024] As described above, the inner wall of the inverse tapered portion 220 of the waveguide 200 and the second tapered portion 103 of the dielectric waveguide 100 are formed to have approximately the same inclination. Therefore, as shown in Figures 2 and 3, when the dielectric waveguide 100 is inserted into the waveguide 200, the inner wall of the inverse tapered portion 220 of the waveguide 200 comes into contact with the side surface of the second tapered portion 103 of the dielectric waveguide 100. This enables transmission of radio waves between the dielectric waveguide 100 and the waveguide 200.

[0025] As described with reference to FIGS. 1 to 3 , the dielectric waveguide 100 and the waveguide 200 are fixed together by inserting a pin 300 into the side of the waveguide 200 with the dielectric waveguide 100 inserted into the waveguide 200. The pin 300 is inserted through the through-hole 111 of the dielectric waveguide 100 and the through-hole 211 of the waveguide 200 shown in FIGS. 4 and 5 . As a result, the pin 300 shown in FIGS. 1 to 3 is provided so as to penetrate the main body 210 of the waveguide 200 and the inner layer 110 of the dielectric waveguide 100. The insertion direction of the pin 300 is the radial direction of the dielectric waveguide 100, which is a direction perpendicular to the electric field caused by the radio waves transmitted through the dielectric waveguide 100. The pin 300 is made of metal. The thickness of the pin 300 is not particularly limited, and may be determined to be an appropriate size depending on the thickness of the dielectric waveguide 100, for example.

[0026] Incidentally, when a metal pin 300 is inserted so as to pass through the inner layer portion 110 of the dielectric waveguide 100 and radio waves are transmitted to the dielectric waveguide 100, radio wave loss (transmission loss) occurs due to waves reflected by the pin 300. Therefore, in this embodiment, as shown in Figures 1 to 3, a pair of pins 300 are inserted into the waveguide 200 and the dielectric waveguide 100. By appropriately arranging the two pins 300, the waves reflected by each pin 300 are canceled out, thereby suppressing transmission loss.

[0027] Specifically, the two pins 300 are arranged side by side along the longitudinal direction of the dielectric waveguide 100 and the waveguide 200. The spacing between the two pins 300 to suppress transmission loss is determined based on the wavelength of the radio waves to be transmitted. Specifically, the spacing between the two pins 300 is preferably approximately 1 / 4λg. λg is the guide wavelength of the waveguide 200. However, when the wavelength of the radio waves to be transmitted is short, it may be difficult to form the through holes 111, 211 at a spacing of 1 / 4λg by machining. For example, when the radio waves to be transmitted are in the millimeter wave band, 1 / 4λg is approximately 1 mm, making it difficult to form the through holes 111, 211 with high precision. In such cases, the spacing between the pins 300 may be approximately 3 / 4λg instead of 1 / 4λg. Although a spacing of 3 / 4λg between the pins 300 is inferior to that of 1 / 4λg, transmission loss can be suppressed to some extent.

[0028] <Transmission characteristics> FIG. 6 shows the transmission characteristics of the dielectric waveguide 100 and the waveguide 200. FIG. 6(A) shows the reflection characteristics, and FIG. 6(B) shows the transmission characteristics. In the example shown in FIG. 6, the 60 GHz band is assumed as the frequency band of the radio waves transmitted through the dielectric waveguide 100 and the waveguide 200. In FIG. 6(A), the solid line graph (integrated) shows the overall reflection characteristics including the dielectric waveguide 100 and the waveguide 200. The dashed line graph (fixed portion) shows the reflection characteristics of the fixed portion between the dielectric waveguide 100 and the waveguide 200 by the pin 300.

[0029] Figure 6(A) shows that the reflection characteristics are reduced around 60 GHz both overall and at the fixed connection points, suppressing loss due to reflected waves. Figure 6(B) shows that good transmission characteristics are obtained over a wide frequency range, including 60 GHz.

[0030] FIG. 7 shows the change in transmission characteristics depending on the spacing between two pins 300. FIG. 7(A) shows reflection characteristics, and FIG. 7(B) shows transmission characteristics. The examples shown in FIGS. 7(A) and 7(B) compare the difference in characteristics when the spacing between two pins 300 is changed. Here, the 60 GHz frequency band is assumed, and the cases where the spacing between pins 300 is 3 / 4λg and 1 / 4λg are shown. Since the radio wave frequency is 60 GHz, if the spacing between pins 300 is d, then 3 / 4λg is approximately 3.3 mm, and 1 / 4λg is approximately 1.1 mm. In FIGS. 7(A) and 7(B), the solid line graph (d=3.3) shows the characteristics when the spacing between pins 300 is 3.3 mm. The dashed line graph (d=1.1) shows the characteristics when the spacing between pins 300 is 1.1 mm.

[0031] Referring to Figure 7(A), the reflection characteristics when d = 3.3 mm (3 / 4λg) are inferior to those when d = 1.1 mm (1 / 4λg), but the loss due to reflected waves is sufficiently suppressed around 60 GHz, and good results are obtained. Also, referring to Figure 7(B), it can be seen that good transmission characteristics are obtained over a wide frequency range including 60 GHz for both d = 3.3 mm (3 / 4λg) and d = 1.1 mm (1 / 4λg).

[0032] Fig. 8 is a diagram showing the reflection characteristics of pin 300 when configured so that pin 300 does not come into direct contact with the outer circumferential surface of waveguide 200. The example shown in Fig. 8 assumes a frequency band around 27 GHz. When the outer circumferential surface of waveguide 200 is covered with a protective member, metal pin 300 does not come into direct contact with waveguide 200 at the outer circumferential surface of waveguide 200. Referring to Fig. 8, it can be seen that even in this case, loss due to reflected waves is suppressed near the desired frequency, and good results are obtained.

[0033] Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above embodiments. For example, in the above embodiments, the pins 300 are paired together, but the number of pins 300 is not limited to two as long as transmission loss due to reflected waves from the pins 300 can be suppressed. Furthermore, in the above embodiments, the spacing between the two pins 300 is set to 1 / 4λg or 3 / 4λg, but the spacing between the pins 300 is not limited to these distances as long as transmission loss due to reflected waves from the pins 300 can be suppressed. Various other modifications and alternative configurations that do not deviate from the scope of the technical concept of the present invention are included in the present invention. [Explanation of symbols]

[0034] 100...dielectric waveguide, 101...first tapered portion, 102...thin shaft portion, 103...second tapered portion, 104...thick shaft portion, 110...inner layer portion, 111...through hole, 120...outer layer portion, 200...waveguide, 210...main body portion, 211...through hole, 220...reverse tapered portion

Claims

1. a dielectric waveguide having an inner layer portion and an outer layer portion having different dielectric constants; a cylindrical waveguide into which at least a portion of the dielectric waveguide can be inserted; a pin that penetrates the waveguide and the dielectric waveguide at a portion where the dielectric waveguide is inserted into the waveguide; A connection structure between a dielectric waveguide and a waveguide, comprising:

2. The pin is The dielectric waveguide and the waveguide are provided so as to be oriented perpendicular to the electric field of the radio wave transmitted therethrough.

2. The connection structure between a dielectric waveguide and a waveguide according to claim 1.

3. The pin is Two of the dielectric waveguides are arranged side by side along the longitudinal direction of the waveguide.

2. The connection structure between a dielectric waveguide and a waveguide according to claim 1.

4. 4. The connection structure between a dielectric waveguide and a waveguide according to claim 3, wherein the distance between the two pins is approximately 1 / 4 of the guide wavelength of the radio waves transmitted through the waveguide.

5. 4. The connection structure between a dielectric waveguide and a waveguide according to claim 3, wherein the distance between the two pins is approximately 3 / 4 of the guide wavelength of the radio waves transmitted through the waveguide.

6. 2. The connection structure between a dielectric waveguide and a waveguide according to claim 1, wherein the end of the dielectric waveguide that is inserted into the waveguide has a tapered shape in which the diameter gradually decreases toward the tip.

7. 7. The connection structure between a dielectric waveguide and a waveguide according to claim 1, wherein the waveguide has an end portion into which the dielectric waveguide is inserted, the end portion having a tapered shape with a diameter gradually increasing toward a tip.

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