Waveguide tube

Abstract

A first waveguide tube (10) and a second waveguide tube (20) of a waveguide tube (1) are assembled in a state in which electromagnetic waves can be transmitted through a first waveguide hole (11) and a second waveguide hole (21), the second waveguide hole is formed into a rounded polygonal shape or a circular shape at an opening of a surface (20a) of the second waveguide tube facing the first waveguide tube, and the second waveguide tube is configured by disposing a metal coating film on a resin molded article. A choke groove (22) is formed around the second waveguide hole, and the choke groove is formed such that the length (L) between the wall surface (21a) of the second waveguide hole and the inner wall surface (22a) of the choke groove on the second waveguide hole side is constant along the circumferential direction of the second waveguide hole.

Description

Technical Field

[0001] The present disclosure relates to waveguides. Background Art

[0002] Conventionally, a waveguide for transmitting a high-frequency electromagnetic field has been proposed, for example, in Patent Document 1. Specifically, the waveguide includes: a first waveguide formed of a wiring substrate or the like and having a first waveguide hole formed therein; and a second waveguide formed of a metal and having a second waveguide hole formed therein. Furthermore, the waveguide is configured such that the first waveguide and the second waveguide are joined in such a manner that the first waveguide hole and the second waveguide hole communicate with each other.

[0003] Furthermore, in this waveguide, when a gap is generated between the first waveguide and the second waveguide, a choke groove that substantially surrounds the first waveguide hole is formed in the first waveguide so as to suppress leakage of an electromagnetic field through the gap.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 5094871 Summary of the invention

[0007] In addition, the inventors of the present application studied a technique of making the second waveguide a resin molded product including plastic or the like and forming a choke groove that substantially surrounds the second waveguide hole in order to reduce the number of processing steps and reduce the weight. However, the inventors of the present application confirmed through their research that structural defects such as partial collapse between the second waveguide hole and the choke groove may occur depending on the shape of the second waveguide hole and the shape of the choke groove.

[0008] An object of the present disclosure is to provide a waveguide having a second waveguide formed of a resin molded product, wherein the waveguide can suppress the occurrence of structural defects in a portion between a second waveguide hole and a choke groove.

[0009] According to a technical solution of the present disclosure, a waveguide tube comprises: a first waveguide tube, which is formed with a first waveguide hole; and a second waveguide tube, which is assembled to the first waveguide tube in a state with a specified gap and is formed with a second waveguide hole; the first waveguide tube and the second waveguide tube are assembled in a state in which electromagnetic waves can be transmitted in the first waveguide hole and the second waveguide hole; the opening of the second waveguide hole on a side of the second waveguide tube opposite to the first waveguide tube is formed into a rounded polygonal shape or a circular shape; the second waveguide tube is constituted by arranging a metal film on a resin molded product, and a choke groove is formed around the second waveguide hole; the choke groove is formed so that the length between the wall surface of the second waveguide hole and the inner wall surface of the choke groove on the second waveguide hole side is constant along the circumferential direction of the second waveguide hole.

[0010] Thus, when the molten resin is poured into the mold to produce the resin molded product having the second waveguide hole and the choke groove formed therein, the resin can easily and evenly flow between the wall surface of the second waveguide hole and the inner wall surface of the choke groove. Therefore, it is possible to suppress the occurrence of structural defects such as partial collapse between the wall surface of the second waveguide hole and the inner wall surface of the choke groove on the second waveguide hole side. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a perspective view of the waveguide according to the first embodiment.

[0012] Figure 2 is along the Figure 1 Cross-sectional view of line IIA-IIA in .

[0013] Figure 2B This is an enlarged cross-sectional view of a portion on one surface side of the second waveguide.

[0014] Figure 3 It is a top view of one side of the second waveguide.

[0015] Figure 4 This is a schematic cross-sectional view when a millimeter wave radar is constructed using the waveguide of the first embodiment.

[0016] Figure 5 This is a graph showing the relationship between frequency and pass characteristics.

[0017] Figure 6 It is a diagram showing the relationship between the length between the second waveguide hole and the inner wall surface of the choke slot and the reflection characteristics.

[0018] Figure 7 It is a diagram showing the relationship between the length between the second waveguide hole and the inner wall surface of the choke slot and the reflection characteristics.

[0019] Figure 8 It is a diagram showing the relationship between the length between the second waveguide hole and the inner wall surface of the choke slot and the transmission characteristics.

[0020] Fig. 9 It is a diagram showing the relationship between the length between the second waveguide hole and the inner wall surface of the choke slot and the transmission characteristics.

[0021] Fig.10 This is a diagram showing the relationship between the sum of the length between the second waveguide hole and the inner wall surface of the choke groove and the depth of the choke groove and the transmission characteristics.

[0022] Fig.11 It is a diagram for explaining the dimensions of the second waveguide according to the first embodiment.

[0023] Fig.12 It is a diagram for explaining the dimensions of the second waveguide of the comparative example.

[0024] Fig.13 It is a plan view of one surface side of the second waveguide according to the modification example of the first embodiment.

[0025] Fig.14 It is a plan view of one surface side of the second waveguide according to the modification example of the first embodiment.

[0026] Fig.15 It is a plan view of one surface side of the second waveguide according to the modification example of the first embodiment.

[0027] Fig.16 It is a plane on one surface side of the second waveguide in the second embodiment.

[0028] Fig.17 This is a diagram showing the relationship between the angle of the arc portion and the passing characteristics.

[0029] Fig.18 It is a top view of one surface side of the second waveguide according to a modification example of the second embodiment.

[0030] Fig.19 This is a perspective view of the second waveguide according to the third embodiment.

[0031] Fig. 20 It is a cross-sectional view of the waveguide according to the third embodiment.

[0032] Fig.21 This is a diagram showing the relationship between the length between the outer wall surface of the choke slot and the first end surface and the second end surface and the passage characteristics. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present disclosure will be described based on the drawings.

[0034] In the following embodiments, the same or equivalent parts are described with the same reference numerals.

[0035] (First embodiment)

[0036] The waveguide 1 according to the first embodiment will be described with reference to the drawings. The waveguide 1 according to the present embodiment is preferably used for transmitting a high-frequency electromagnetic field, for example.

[0037] like Figure 1 and Figure 2A As shown, the waveguide 1 includes a first waveguide 10 and a second waveguide 20, which are assembled together. Figure 1 The figure shows a first waveguide 10 and a second waveguide 20 that are spaced far apart so that the shapes of a second waveguide hole 21 and a choke groove 22 to be described later can be understood.

[0038] The first waveguide 10 is composed of a printed circuit board, a wiring board, etc. having one surface 10a and the other surface 10b, and is formed with a first waveguide hole 11 that passes through the one surface 10a and the other surface 10b. The first waveguide hole 11 is formed by drilling or the like, and the opening is formed in a shape substantially the same as the opening of the second waveguide hole 21 described later. Although not shown in the figure, a metal film of about 1 μm made of aluminum, copper, silver, etc. is arranged in the first waveguide hole 11.

[0039] The second waveguide 20 is formed into a plate having one surface 20a and another surface 20b. Figure 2B As shown in FIG. 2 , the second waveguide 20 is formed by coating a metal film 201 on a resin molded article 200. Figure 1 and Figure 2A As shown, a second waveguide hole 21 penetrating between one surface 20a and the other surface 20b is formed, and a choke groove 22 is formed around the second waveguide hole 21 on one surface 20a.

[0040] The resin molded article 200 is made of a resin material such as ABS (Acrylonitrile Butadiene Styrene) or PPE (Poly Phenylene-Ether). The metal film 201 is made of aluminum, copper, silver, etc., and is formed to have a thickness of about 1 μm. The molten resin is poured into the mold and solidified to form the resin molded article 200 having the second waveguide hole 21 and the choke slot 22. The metal film 201 is then disposed on the entire surface of the resin molded article 200 by sputtering, vapor deposition, etc., to form the second waveguide tube 20. Figure 2A In the figure, the metal film 201 is omitted because the thickness of the metal film 201 is sufficiently thin relative to the resin molded product 200. In addition, the metal film 201 in the second waveguide 20 of the present embodiment is formed on the entire surface of the resin molded product 200. Therefore, each surface of the second waveguide 20, including one surface 20a and the other surface 20b, is composed of the metal film 201.

[0041] Here, refer to Figure 3 The shapes of the second waveguide hole 21 and the choke slot 22 of the second waveguide 20 of the present embodiment are described. In the following description, a direction along the surface direction of one surface 20a in the second waveguide 20 is defined as the X-axis direction, a direction perpendicular to the X-axis direction and along the surface direction of one surface 20a is defined as the Y-axis direction, and a normal direction to one surface 20a is defined as the Z-axis direction.

[0042] like Figure 3As shown in FIG. 1 , the opening of the second waveguide hole 21 on the side of one surface 20a is formed into a rounded polygonal shape. In other words, the opening of the second waveguide hole 21 on the side of one surface 20a is formed into a shape without corners. In other words, the opening of the second waveguide hole 21 on the side of one surface 20a is formed into a shape in which the corners of the polygonal shape have curvature. In addition, the rounded polygonal shape can be exemplified by a rounded rectangular shape, a rounded hexagonal shape, and the like.

[0043] In the present embodiment, the opening of the second waveguide hole 21 is formed into a rounded rectangular shape, with the long side parallel to the X-axis direction and the short side parallel to the Y-axis direction, and the ends of the two opposite sides along the X-axis direction are connected by a circular arc. Hereinafter, an example in which the opening of the second waveguide hole 21 is formed into a rounded polygonal shape will be described, but the second waveguide hole 21 may be a circular shape or the like as long as it has no corners. In this case, the circular shape includes an elliptical shape or the like in addition to a perfect circle.

[0044] In the present embodiment, the choke groove 22 is formed in a frame shape to surround the second waveguide hole 21. In addition, the choke groove 22 is formed so that the length L between the wall surface 21a of the second waveguide hole 21 and the inner wall surface 22a of the choke groove 22 on the second waveguide hole 21 side is constant (constant) along the circumferential direction of the second waveguide hole 21. In other words, the choke groove 22 is formed so that the surface after the wall surface 21a of the second waveguide hole 21 is uniformly moved parallel to the outside is the inner wall surface 22a. In other words, if the portion between the second waveguide hole 21 and the choke groove 22 is defined as the wall portion 23, the choke groove 22 is formed so that the thickness of the wall portion 23 is constant along the circumferential direction of the second waveguide hole 21. In addition, along the circumferential direction of the second waveguide hole 21, in other words, it can also be said that it is along the direction of the axis passing through the center of the second waveguide hole 21. As described above, the second waveguide hole 21 is formed into a shape without corners so that the length L between the wall surface 21 a of the second waveguide hole 21 and the inner wall surface 22 a of the choke slot 22 is constant along the circumferential direction of the second waveguide hole 21 .

[0045] The above are the shapes of the second waveguide hole 21 and the choke groove 22 of the present embodiment. Furthermore, in the case of manufacturing the resin molded product 200 formed with such a second waveguide hole 21 and the choke groove 22, it is sufficient to prepare a mold having protrusions or the like arranged at the portions corresponding to the second waveguide hole 21 and the choke groove 22, and allow the molten resin to flow into the mold and solidify. In this case, in the present embodiment, the length L between the wall surface 21a of the second waveguide hole 21 and the inner wall surface 22a of the choke groove 22 is constant along the circumference of the second waveguide hole 21. Therefore, when the molten resin is allowed to flow in, for example, compared with the case where the length L between the wall surface 21a of the second waveguide hole 21 and the inner wall surface 22a of the choke groove 22 is uneven along the circumference of the second waveguide hole 21, the resin can easily flow evenly between the wall surface 21a of the second waveguide hole 21 and the inner wall surface 22a of the choke groove 22. Therefore, it is possible to suppress the occurrence of structural defects such as collapse of the portion between the wall surface 21 a of the second waveguide hole 21 and the inner wall surface 22 a of the choke groove 22 (that is, the wall portion 23 ).

[0046] And, if Figure 2A As shown, the first waveguide 10 and the second waveguide 20 are assembled in a state where the other surface 10b of the first waveguide 10 and the one surface 20a of the second waveguide 20 are opposed to each other in the Z-axis direction. Specifically, in order to cope with warping caused by the difference in thermal expansion between the first waveguide 10 and the second waveguide 20, the first waveguide 10 and the second waveguide 20 are assembled in a state where a predetermined gap g is previously formed between the other surface 10b of the first waveguide 10 and the one surface 20a of the second waveguide 20. In addition, the first waveguide 10 and the second waveguide 20 are assembled in a state where electromagnetic waves can be transmitted to the first waveguide hole 11 and the second waveguide hole 21, for example, in a manner where the center of the first waveguide hole 11 on the other surface 10b side and the center of the second waveguide hole 21 on the one surface 20a side are opposed to each other. In addition, the first waveguide 10 and the second waveguide 20 are assembled, for example, in a manner where the center of the first waveguide hole 11 on the other surface 10b side and the center of the second waveguide hole 21 on the one surface 20a side are opposed to each other. Figure 2A In different cross sections, a recessed portion for engagement is formed in the first waveguide 10 and a protruding portion for engagement is formed in the second waveguide 20, and the protruding portion for engagement is inserted into the recessed portion for engagement, thereby assembling. In this case, the first waveguide 10 and the second waveguide 20 are assembled by appropriately adjusting the depth of the recessed portion for engagement and the height of the protruding portion for engagement, thereby adjusting the length of the gap g.

[0047] The above is the structure of the waveguide 1 of the present embodiment. Next, a method of using the waveguide 1 will be described, and a more detailed structure and effect will be described.

[0048] The waveguide 1 is used to construct a millimeter wave radar having a plurality of antennas arranged therein, such as Figure 4As shown, one side 10a of the first waveguide 10 is joined to a semiconductor module 30 having an antenna portion 31 via a joining member 40 such as solder. The semiconductor module 30 is, for example, structured as follows: a wiring substrate 32 having an antenna portion 31 formed thereon, and a mold resin 33 that seals the wiring substrate 32 so that the antenna portion 31 is exposed.

[0049] Furthermore, in this embodiment, since the first waveguide 10 and the second waveguide 20 are assembled while maintaining a predetermined gap g, the electromagnetic field may leak from the gap g. However, the choke groove 22 is formed on the second waveguide 20 as described above. Therefore, it is possible to suppress the transmission characteristics from being deteriorated.

[0050] Specifically, the inventors of the present application have conducted a special study on the transmission characteristic S21 of the waveguide 1 and obtained Figure 5 Results shown. Figure 5 It is a diagram showing the relationship between frequency and the through characteristic S21, with the input side being the first waveguide 10 and the output side being the second waveguide 20. In addition, the through characteristic S21 and the reflection characteristic S11 described later are respectively set at the input side to be the first waveguide 10 and at the output side to be the second waveguide 20.

[0051] also, Figure 5 This is the result when the electrically executed wavelength λ is set to 3.92 mm (ie, λ=3.92 mm). Figure 5 Yes Figure 3 As shown in the figure, the length L between the wall surface 21a of the second waveguide hole 21 and the inner wall surface 22a of the choke slot 22 (i.e., the thickness of the wall portion 23) is set to 0.3mm≈0.0765λ, and the width W between the inner wall surface 22a and the outer wall surface 22b of the choke slot 22 is set to 0.475mm≈0.121λ. In addition, Figure 5 This is the result when the depth d of the choke slot 22 is set to 1.4 mm ≈ 0.35 λ and the gap g is set to 0.1 mm. In addition, the length between the wall surface 21a of the second waveguide hole 21 and the inner wall surface 22a of the choke slot 22 (i.e., the thickness of the wall portion 23) is simply referred to as the length L, and the width between the inner wall surface 22a and the outer wall surface 22b of the choke slot 22 is also simply referred to as the width W. And, Figure 5 The waveguide of the comparative example is a waveguide in which the second waveguide 20 is made of metal and the length L and the width W are set to 1 / 4 of the wavelength λ (i.e., 3.92 mm) to be executed. Figure 5 The waveguide without a choke groove is a waveguide in which the second waveguide 20 is made of metal and the choke groove 22 is not formed.

[0052] like Figure 5 As shown, in the case of a waveguide without a choke groove 22, it was confirmed that there was an energy leakage of about -0.5 dB at an operating frequency of 76.5 GHz, which is generally used in millimeter wave radars. However, for the waveguide 1 of this embodiment, it was confirmed that there was substantially no leakage at 76.5 GHz, and it was confirmed that it was possible to obtain a substantially similar pass characteristic S21 as the waveguide of the comparative example. In other words, it was confirmed that even if the second waveguide 20 was constructed in a manner including the resin molded article 200, it was possible to obtain the same pass characteristic S21 as when the second waveguide 20 was constructed of metal.

[0053] In addition, the inventor of the present application investigated the relationship between the length L and the reflection characteristic S11 and the relationship between the length L and the transmission characteristic S21 when the depth d is fixed at 1.4 mm and the width W is changed to 0.2 mm, 0.3 mm, 0.5 mm, and 1.0 mm, and obtained Figure 6 to Figure 9 The results are shown. Figure 6 and Figure 8 The length L is expressed in mm. Figure 7 and Fig. 9 In the above equation, the length L is represented by the wavelength λ of the electrical execution. Figure 6 to Figure 9 As shown, it is confirmed that even if the width W is changed, the influence on the reflection characteristic S11 and the passing characteristic S21 is small. Therefore, the width W can be appropriately changed according to the ease of forming the resin molded product 200 constituting the second waveguide 20. However, the wider the width W, the wider the area where the reflection characteristic S11 becomes smaller. Therefore, the width W is preferably appropriately changed according to the application. In addition, it is considered that the reflection characteristic S11 can fully meet the current requirements as long as it is below -20dB.

[0054] In addition, the inventors of the present application have also conducted a special study on the relationship between the sum of the length L and the depth d and the passing characteristic S21, and obtained Fig.10 The results are shown. In addition, Fig.10 The graph shows the results when the representative operating frequency is 76.5 GHz and the electrically executed wavelength λ is 3.92 mm (ie, λ=3.92 mm).

[0055] like Fig.10As shown, it was confirmed that as long as the sum of the length L1 and the depth d is within the range of 0.2 to 0.7λ of the operating frequency, the deterioration of the passage characteristic S21 can be fully suppressed. Here, in the past, the length L was usually set to 1 / 4λ and the depth d was set to 1 / 4λ. However, through the research of the inventors of the present application, it was confirmed that as long as the sum of the length L1 and the depth d is within the range of 0.2 to 0.7λ of the operating frequency as described above, the deterioration of the passage characteristic S21 can be fully suppressed. Therefore, for the second waveguide 20 of the present embodiment, as long as the sum of the length L and the depth d is 0.2 to 0.7λ of the operating frequency, the values ​​of the length L and the depth d can be appropriately changed.

[0056] For example, Fig.11 and Fig.12 As shown, it is assumed that the second waveguide hole 21 is at the opening, the short side length a is 1.55 mm, and the width W is 0.475 mm. Fig.11 As shown in FIG. 1 , the opening of the second waveguide hole 21 of this embodiment is formed into a rounded rectangular shape. Fig.12 As shown in FIG. 1 , the opening of the second waveguide hole 21 of the comparative example is set to be rectangular. Fig.11 As shown in FIG. 1 , the length L is set to 0.3 mm (i.e., 0.07λ), and in the waveguide of the comparative example, the length L is set to 0.98 mm (i.e., 1 / 4λ). However, in the present embodiment, the depth d is appropriately adjusted so that the sum of the length L and the depth d is 0.2 to 0.7λ. In this case, the length of the outer wall surface 22b of the choke slot 22 opposite to each other in the Y-axis direction is Fig.11 3.1mm in the middle Fig.12 That is, in this embodiment, the length in the Y-axis direction can be shortened by approximately 30%, and miniaturization in the Y-axis direction can be achieved.

[0057] Although not particularly shown, as long as the sum of the length L and the depth d is 0.2 to 0.7λ, the length L of the choke slot 22 may be longer. Furthermore, when the choke slot 22 is formed so as to have a longer length L, the thickness of the wall portion 23 is thicker. Therefore, when the length L is longer, the strength of the wall portion 23 can be increased, and the manufacturing process can be simplified.

[0058] According to the present embodiment described above, the second waveguide tube 20 is constituted by including a resin molded article 200. Furthermore, the choke groove 22 is formed so that the length L between the wall surface 21a of the second waveguide hole 21 and the inner wall surface 22a of the choke groove 22 is constant along the circumferential direction of the second waveguide hole 21. Therefore, when the molten resin is flowed into the mold to manufacture the resin molded article 200 formed with such a second waveguide hole 21 and the choke groove 22, the resin easily flows evenly between the wall surface 21a of the second waveguide hole 21 and the inner wall surface 22a of the choke groove 22. Therefore, it is possible to suppress the occurrence of structural defects such as the collapse of the portion between the wall surface 21a of the second waveguide hole 21 and the inner wall surface 22a of the choke groove 22 on the second waveguide hole 21 side (i.e., the wall portion 23).

[0059] In the present embodiment, the choke groove 22 is formed in a frame shape so as to surround the second waveguide hole 21. Therefore, it is possible to easily suppress leakage of electromagnetic waves from the gap g.

[0060] In the present embodiment, the sum of the length L and the depth d of the second waveguide 20 is set to 0.2 to 0.7λ of the operating frequency. Therefore, when the length L is shortened within the range of 0.2 to 0.7λ of the operating frequency, the second waveguide 20 can be miniaturized. On the other hand, when the length L is increased within the range of 0.2 to 0.7λ of the operating frequency, the strength of the wall portion 23 can be increased, and the manufacturing process can be simplified.

[0061] (Variation of the first embodiment)

[0062] A modified example of the first embodiment is described. As described in the first embodiment, the opening of the second waveguide hole 21 on the side of the one surface 20a does not have a corner, and the detailed shape can be changed appropriately as long as the thickness of the wall portion 23 is constant. For example, Fig.13 As shown, the second waveguide hole 21 may also be a rounded rectangular shape having two opposite sides along the X-axis direction and two opposite sides along the Y-axis direction, and these sides are connected by arcs. Fig.14 As shown, the second waveguide hole 21 may be formed in a circular shape. In these cases, the choke groove 22 is also formed around the second waveguide hole 21 so that the thickness of the wall portion 23 is constant.

[0063] In addition, as described in the first embodiment, the width W of the choke slot 22 is unlikely to affect the transmission characteristics, so Fig.15 As shown, the choke groove 22 may be formed in a shape in which the outer wall surface 22 b is raised toward the side opposite to the second waveguide hole 21 .

[0064] (Second embodiment)

[0065] The second embodiment will be described. This embodiment is a form in which the shape of the choke groove 22 is changed from the first embodiment. The rest is the same as the first embodiment, so the description is omitted here.

[0066] like Fig.16 As shown, the choke slot 22 of this embodiment is in a state where a notch portion 220 is formed. Specifically, the second waveguide hole 21 is similar to the first embodiment, and the shape of the opening portion on one surface 20a is formed into a rounded rectangular shape with the X-axis direction as the long side direction. In addition, the choke slot 22 is formed in the portion opposite to the second waveguide hole 21 in the Y-axis direction, and is not formed in the portion opposite to the second waveguide hole 21 in the X-axis direction. That is, the choke slot 22 is formed with the notch portion 220 so as not to have a portion opposite to the second waveguide hole 21 in the X-axis direction.

[0067] The above is the structure of the waveguide 1 of the present embodiment. Such a waveguide 1 is used to constitute a millimeter wave radar, for example, in the same manner as the first embodiment described above. In this case, it is known that when a transmission wave is transmitted to the waveguide 1 in the Te10 mode, the transmission wave is likely to leak along the Y-axis direction (i.e., the direction orthogonal to the long side direction of the second waveguide hole 21) in the gap g between the first waveguide 10 and the second waveguide 20. Therefore, the choke slot 22 of the present embodiment is formed in the portion where the transmission wave is likely to leak, i.e., the portion opposite to the second waveguide hole 21 in the Y-axis direction.

[0068] Furthermore, the inventor of the present application has conducted a special study on the size of the notch 220 and the passing characteristic S21 and obtained Fig.17 The results are shown. In addition, Fig.17 This is a diagram showing the results when the representative operating frequency is 76.5 GHz and the electrically executed wavelength λ is 3.92 mm (i.e., λ=3.92 mm). Fig.17 Yes Fig.16 The result shown is when the length X of the long side along the X-axis direction of the second waveguide hole 21 is set to 1.4 mm, the length Y of the short side along the Y-axis direction is set to 1.15 mm, and the radius A of the arc connecting the two opposite sides extending along the X-axis direction is set to 0.575 mm. Fig.17 Yes Fig.16 The result is shown in the case where the width W is set to 0.475 mm ≈ 0.121λ, the length L is set to 0.3 mm ≈ 0.0765λ, and R is set to 1.1125 mm ≈ 0.283λ, where R is the length between the center between the ends of the two opposite sides of the second waveguide hole 21 along the X-axis direction and the center between the inner wall surface 22a and the outer wall surface 22b of the arc portion along the arc shape of the second waveguide hole 21. And, Fig.17This is a result of changing the angle θ, where the angle of the portion of the choke groove 22 that follows the arc of the second waveguide hole 21 is defined as the angle θ.

[0069] like Fig.17 As shown in FIG. 1 , the larger the angle θ is, the closer the pass characteristic S21 is to 0. That is, the larger the portion of the choke slot 22 surrounding the second waveguide hole 21 is, the closer the pass characteristic S21 is to 0. Figure 5 As described above, the pass characteristic S21 in the case where there is no choke groove is -0.5 dB, and therefore it is preferable to select an angle θ at which the pass characteristic S21 is -0.5 dB or more according to the depth d.

[0070] According to the present embodiment described above, since the second waveguide 20 is configured including the resin molded product 200 and the thickness of the wall portion 23 is set constant, the same effects as those of the first embodiment can be obtained.

[0071] As in the present embodiment, the choke groove 22 may not be formed in a shape that completely surrounds the second waveguide hole 21. In such a case, it is preferable to form the choke groove 22 at a portion where the transmission wave is likely to leak from the gap g. In addition, for such a second waveguide tube 20, since the choke groove 22 that completely surrounds the second waveguide hole 21 is not formed, it is easy to control the flow of the resin when the resin molded article 200 constituting the second waveguide tube 20 is formed, and the manufacturing process can be simplified.

[0072] (Variation of the Second Embodiment)

[0073] A modification of the second embodiment described above is described below. Fig.18 As shown, the choke groove 22 may be formed in not only the portion facing the second waveguide hole 21 in the Y-axis direction but also in only one portion facing the second waveguide hole 21 in the X-axis direction.

[0074] (Third embodiment)

[0075] The third embodiment will be described. This embodiment is different from the first embodiment in that a recess is formed in the second waveguide 20. The rest is the same as the first embodiment, so description thereof will be omitted here.

[0076] like Fig.19 and Fig. 20As shown, the waveguide 1 of the present embodiment has a recess 24 formed on one side 20a of the second waveguide 20, at a portion located on the opposite side of the second waveguide hole 21 across the choke groove 22. Furthermore, the second waveguide hole 21 and the choke groove 22 are formed so as to open at the convex portion 25 on the inner edge side formed by forming the recess 24. In the present embodiment, the recess 24 is formed in a rectangular frame shape, and the front end face of the convex portion 25 is formed in a rectangular shape. Specifically, the recess 24 is formed so that the convex portion 25 has an end face along the X-axis direction.

[0077] Furthermore, the first waveguide 10 and the second waveguide 20 are assembled in a state where a predetermined gap g is maintained between the other surface 10 b of the first waveguide 10 and the front end surface of the convex portion 25 of the second waveguide 20 .

[0078] Thus, by forming the recessed portion 24 , the amount of resin required for forming the resin molded product 200 of the second waveguide 20 can be reduced.

[0079] Here, the inventors of the present application have conducted a study on the pass-through characteristic S21 for such a waveguide 1 as follows. That is, the end face of the protrusion 25 along the X-axis direction is set as the first end face 25a and the end face along the Y-axis direction is set as the second end face 25b. In addition, the length between the outer wall surface 22b of the choke slot 22 and the first end face 25a is set as the length by, and the length between the outer wall surface 22b of the choke slot 22 and the second end face 25b is set as the length bx. In addition, the inventors of the present application have conducted a special study on the lengths bx, by and the pass-through characteristic S21 and obtained Fig.21 The results are shown. In addition, Fig.21 The representative operating frequency is 76.5 GHz, the electrically executed wavelength λ is 3.92 mm (i.e., λ=3.92 mm), and the transmission wave is transmitted in the Te10 mode. In addition, as described above, it is known that when the transmission wave is in the Te10 mode, the transmission wave is likely to leak in the Y-axis direction.

[0080] like Fig.21 As shown in FIG. 1 , it is confirmed that even if the length bx is changed, the pass characteristic S21 does not change much, but the longer the length by is, the better the pass characteristic S21 is. Figure 5 As described above, the pass characteristic S21 is -0.5 dB in the absence of the choke slot 22, so it is preferable to set the length by to be greater than 0.2λ so that the pass characteristic S21 is closer to 0 than -0.5 dB. In addition, such waveguides 1 are often arranged in plurality inside a semiconductor module, and the upper limit of the length by is determined by physical constraints.

[0081] According to the present embodiment described above, since the second waveguide 20 is formed using the resin molded product 200 and the thickness of the wall portion 23 is set constant, the same effects as those of the first embodiment can be obtained.

[0082] In the present embodiment, a concave portion 24 is formed at a portion of one side 20a of the second waveguide 20, which is located on the opposite side of the second waveguide hole 21 across the choke groove 22. Therefore, the amount of resin required for the resin molded article 200 constituting the second waveguide 20 can be reduced. In addition, in the present embodiment, the length by is set to be greater than 0.2λ. Therefore, the deterioration of the passage characteristic S21 can be suppressed.

[0083] (Variation of the third embodiment)

[0084] A modified example of the third embodiment described above is described. In the third embodiment described above, a structure in which the amount of resin is reduced by forming the recess 24 is described. In this case, the amount of resin can be further reduced by removing other parts. For example, the second waveguide 20 can also be configured as follows: the excess part is hollowed out (i.e., removed) in such a way that the amount of resin in the part located around the second waveguide hole 21 along the axial direction of the second waveguide hole 21 becomes constant. In such a structure, when the molten resin is made to flow into the mold to manufacture the resin molded product 200, it is easier to control the flow of the resin.

[0085] (Other embodiments)

[0086] The present disclosure is described based on the embodiments, but it should be understood that the present disclosure is not limited to the embodiments or configurations. The present disclosure also includes various modifications or modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms that only include one element, more or fewer elements, also fall within the scope or thought of the present disclosure.

[0087] For example, in the above-described first to third embodiments, the choke groove 22 similar to the second waveguide 20 may be formed in the first waveguide 10 .

[0088] In the above-described first to third embodiments, the first waveguide 10 may be configured by disposing a metal film 201 on a resin molded product 200 similarly to the second waveguide 20 .

[0089] Furthermore, the above-mentioned embodiments can be appropriately combined. For example, the above-mentioned third embodiment can be combined with the above-mentioned second embodiment, and the second waveguide 20 can form the convex portion 25 by forming the concave portion 24 .

Claims

1. A waveguide, have: a first waveguide tube having a first waveguide hole; and The second waveguide is assembled with the first waveguide at a predetermined gap, and has a second waveguide hole. The first waveguide and the second waveguide are assembled in a state where electromagnetic waves can be transmitted through the first waveguide hole and the second waveguide hole. The opening of the second waveguide hole on the side of the second waveguide tube facing the first waveguide tube is formed into a rounded polygonal shape or a circular shape. The second waveguide is formed by disposing a metal film on a resin molded product, and a choke groove is formed around the second waveguide hole. The choke groove is formed so that the length between the wall surface of the second waveguide hole and the inner wall surface of the choke groove on the second waveguide hole side is constant along the circumferential direction of the second waveguide hole.

2. The waveguide according to claim 1, The choke slot is in a frame shape surrounding the second waveguide hole.

3. The waveguide according to claim 1, The opening of the second waveguide hole on the side opposite to the first waveguide is formed into a rounded polygonal shape, with one direction in the surface direction of the one side as the long side direction. The choke groove is formed so as to face the second waveguide hole in a direction intersecting the longitudinal direction in a surface direction of the one surface.

4. The waveguide according to any one of claims 1 to 3, When the wavelength of the transmitted electromagnetic wave is assumed to be λ, the sum of the length between the wall surface of the second waveguide hole and the inner wall surface of the choke groove on the second waveguide hole side and the depth of the choke groove is 0.2 to 0.7λ.

5. The waveguide according to any one of claims 1 to 3, The second waveguide has a recessed portion formed at a portion on the opposite side of the second waveguide hole across the choke groove in one surface facing the first waveguide, and an inner edge of the recessed portion is a convex portion.

6. The waveguide according to claim 5, The opening of the second waveguide hole on the side opposite to the first waveguide is formed into a rounded polygonal shape, with one direction in the surface direction of the one side as the long side direction. The convex portion has an end surface along the longitudinal direction. When the wavelength of the electromagnetic wave to be transmitted is λ, the length between the outer wall surface of the choke slot located on the side opposite to the second waveguide hole and the end surface is greater than or equal to 0.2λ.

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