Transmission device

Abstract

To provide a transmission device capable of reducing transmission loss.SOLUTION: A transmission device for transmitting electromagnetic waves includes a first transmission member 10 having a first transmission path 11 formed thereon, and a second transmission member 20 having a second transmission path 21 formed thereon, the first transmission path 11 is a passage opening into one surface 10a of the first transmission member, the first transmission member 10 and the second transmission member 20 are arranged with a gap provided between them such that the second transmission path 21 faces the one surface 10a, and the first transmission member 10 is formed with a recess 12 opening into a portion of the one surface 10a away from the first transmission path 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a transmission device. [Background technology]

[0002] In a transmission device that transmits electromagnetic waves between an IC (integrated circuit) board, an antenna, etc., a waveguide with a transmission path formed therein is coupled to the board, etc. When a gap occurs between the board, etc. and the waveguide due to warping that occurs during the manufacture of the board, etc., the transmission loss may increase due to leakage electric field from the gap. For example, Patent Document 1 proposes a technology to reduce leakage electric field by providing a periodic structure around the waveguide and operating the members around the waveguide as a metamaterial. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2021 / 0376439 Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the study by the present inventors, it was found that in a transmission device having such a structure, a transmission loss of 0.1 dB or more occurs in a high frequency band such as 77 GHz used in millimeter wave radar and the like.

[0005] In view of the above, an object of the present disclosure is to provide a transmission device capable of reducing transmission loss. [Means for solving the problem]

[0006] In order to achieve the above object, according to one aspect of the present disclosure, a transmission device for transmitting electromagnetic waves includes a first transmission member (10) having a first transmission path (11) formed therein, and a second transmission member (20) having a second transmission path (21) formed therein, the first transmission path being a passage opening into one surface (10a) of the first transmission member, the first transmission member and the second transmission member being arranged with a gap therebetween so that the second transmission path faces the one surface, and the first transmission member is formed with a recess (12) opening into a location on the one surface away from the first transmission path.

[0007] According to this, the leakage electric field from the gap between the first and second transmission members is cancelled by the reflected electric field from the recess, and the transmission loss can be reduced.

[0008] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a transmission device according to a first embodiment. [Diagram 2] 1 is a cross-sectional view of a transmission device according to a first embodiment. [Diagram 3] FIG. 4 is a top view of the first transmission member. [Figure 4] 11A and 11B are diagrams for explaining reduction of leakage electric field by a recessed portion. [Diagram 5] 11A and 11B are diagrams for explaining reduction of leakage electric field by a recessed portion. [Figure 6] FIG. 13 is a diagram showing the distribution of a leakage electric field. [Figure 7] 6 is a diagram showing the relationship between the position in the longitudinal direction of the first transmission line and the electric field. FIG. [Figure 8] FIG. 13 is a diagram showing the relationship between the width of a recess and the transmission loss. [Figure 9] FIG. 13 is a diagram showing the relationship between the depth of a recess and the transmission loss. [Figure 10] 13 is a diagram showing the difference between the equiphase surface of the leakage electric field and the shape of the recess when the opening shape of the recess is linear. FIG. [Figure 11] FIG. 13 is a diagram showing the curvature of an equiphase surface of a leakage electric field. [Figure 12] 11 is a diagram for comparing the shapes of an equiphase surface of a leakage electric field and concentric circles centered on the center of a first transmission line. FIG. [Figure 13] FIG. 13 is a diagram showing a state in which the centers of the concentric circles in FIG. 12 are offset. [Figure 14] 13 is a diagram showing a state in which the center of the recess is offset to the opposite side of the recess with respect to the first transmission line. FIG. [Figure 15] 11 is a diagram for comparing the shape of an equiphase surface of a leakage electric field with that of an ellipse centered on the center of the first transmission line. FIG. [Figure 16] FIG. 13 is a diagram showing the relationship between the central angle of a recess and transmission loss. [Figure 17] FIG. 1 is a diagram showing the relationship between the frequency of an electromagnetic wave and the transmission loss. [Figure 18] FIG. 11 is a top view of a first transmission member in the second embodiment. [Figure 19] FIG. 11 is a cross-sectional view of a transmission device according to a third embodiment. [Figure 20] FIG. 11 is a cross-sectional view of a transmission device according to a fourth embodiment. [Figure 21] FIG. 13 is a cross-sectional view of a transmission device according to a fifth embodiment. [Figure 22] FIG. 13 is a cross-sectional view of a transmission device according to a sixth embodiment. [Diagram 23] FIG. 11 is a top view of a first transmission member according to another embodiment. [Figure 24] FIG. 11 is a top view of a first transmission member according to another embodiment. [Diagram 25] FIG. 11 is a top view of a first transmission member according to another embodiment. [Figure 26] FIG. 11 is a top view of a first transmission member according to another embodiment. [Figure 27] FIG. 11 is a top view of a first transmission member according to another embodiment. [Figure 28] FIG. 11 is a top view of a first transmission member according to another embodiment. [Figure 29] FIG. 11 is a cross-sectional view of a transmission device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0011] (First embodiment) A transmission device according to a first embodiment of the present invention transmits electromagnetic waves, and is used, for example, to transmit electromagnetic waves between an antenna of an on-vehicle radar and an IC board.

[0012] 1 and 2, the transmission device includes a first transmission member 10 and a second transmission member 20. The first transmission member 10 and the second transmission member 20 are waveguides. A first transmission path 11 is formed in the first transmission member 10, and a second transmission path 21 is formed in the second transmission member 20.

[0013] The first transmission member 10 is a rectangular prism-shaped metal member having one surface 10a and another surface 10b opposite to the first surface 10a. Two directions parallel to the first surface 10a and perpendicular to each other are defined as the x-direction and the y-direction, respectively, and a direction perpendicular to both the x-direction and the y-direction, i.e., a normal direction to the first surface 10a, is defined as the z-direction. The first transmission path 11 extends in the z-direction, opens at the first surface 10a and the other surface 10b, and serves as a passage connecting the first surface 10a and the other surface 10b.

[0014] The second transmission member 20 is a rectangular prism-shaped metal member having one surface 20a and another surface 20b opposite to the first surface 20a. The second transmission member 20 is disposed such that the first surface 20a and the other surface 20b are parallel to the first surface 10a and the other surface 10b. The second transmission path 21 extends in the z direction, opens at the first surface 20a and the other surface 20b, and serves as a passage connecting the first surface 20a and the other surface 20b.

[0015] The first transmission member 10 and the second transmission member 20 are connected such that the opening of the first transmission path 11 on one surface 10a faces the opening of the second transmission path 21 on the other surface 20b. However, a gap S is formed between the first transmission member 10 and the second transmission member 20. The gap S is generated, for example, by warping of the first transmission member 10 or the second transmission member 20.

[0016] The opening shapes on the one surface 10a and the other surface 10b of the first transmission line 11 and the opening shapes on the one surface 20a and the other surface 20b of the second transmission line 21 are configured to transmit electromagnetic waves in a fundamental mode frequency band. The fundamental mode is a mode with the lowest cutoff frequency among the forms of electromagnetic wave distribution in the first transmission member 10 and the second transmission member 20, and is, for example, the TE01 mode.

[0017] Specifically, the opening shape of the first transmission path 11 is a shape having a longitudinal direction and a lateral direction that are parallel to one surface 10a and perpendicular to each other. In this embodiment, the opening shape of the first transmission path 11 is a rectangle with the x direction as the longitudinal direction and the y direction as the lateral direction. As shown in FIG. 3, the center of the rectangle constituting the opening shape of the first transmission path 11 in the xy plane is P1. The opening shape of the second transmission path 21 is a rectangle with the x direction as the longitudinal direction and the y direction as the lateral direction.

[0018] The first transmission line 11 has a cross section parallel to the xy plane that is the same as the opening shape on the one surface 10a and the other surface 10b. The second transmission line 21 has a cross section parallel to the xy plane that is the same as the opening shape on the one surface 20a and the other surface 20b.

[0019] The first transmission member 10 has a recess 12 formed on one surface 10a, the recess 12 opening at a location away from the first transmission path 11. The recess 12 is for reducing leakage of an electric field from the gap S.

[0020] The recesses 12 are formed on both sides of the first transmission line 11 in the y direction, one on each side. As shown in Fig. 3, the recesses 12 formed on one side and the other side of the first transmission line 11 in the y direction are respectively referred to as recesses 12a and 12b. The recesses 12a and 12b are each shaped to be line-symmetrical with respect to a line L1 that passes through the center P1 and is parallel to the y direction. The recesses 12a and 12b are also arranged to be line-symmetrical with respect to a line L2 that passes through the center P1 and is parallel to the x direction.

[0021] The recesses 12a and 12b each have an arc-shaped opening on the surface 10a. The arc that defines the opening shape of the recesses 12a and 12b is designated as L3, and the center of the arc L3 is designated as P2. The center P2 is located at a position different from the center P1 on the straight line L1.

[0022] As shown in FIG. 2 and FIG. 3, the widths of the first transmission line 11 in the x direction and the y direction are a and b, respectively. The width of the recess 12 in the x direction is L. The width of the recess 12 in the direction perpendicular to both the arc L3 and the z direction is w. The depth of the recess 12 in the z direction is d. The width w and the depth d are designed to be larger than a predetermined value and constant throughout the recess 12, but may vary due to processing accuracy, and the corners may be rounded. The distance between the center P1 and the center P2 is db. The radius of the arc L3 is r. The central angle of the arc L3 is θ. The width of the gap S in the z direction is δ. The length in the z direction from the other surface 10b to the one surface 20a is Lw. The widths of the first transmission member 10 in the x direction and the y direction are aw and bw, respectively. The widths of the second transmission member 20 in the x direction and the y direction are the same as those of the first transmission member 10. The widths of the second transmission line 21 in the x and y directions are the same as those of the first transmission line 11 .

[0023] The principle of reducing the leakage electric field by the recess 12 will be described. When electromagnetic waves are transmitted as indicated by the arrow A1 in FIG. 4, as indicated by the arrow A2, the electric field leaks and spreads outside the transmission device through the gap S from the first transmission path 11. However, a part of this electric field enters the recess 12 as indicated by the arrow A3 and is reflected at the bottom of the recess 12. A part of the electric field reflected by the recess 12 returns to the first transmission path 11 as indicated by the arrow A4, and the other part heads outside the transmission device as indicated by the arrow A5.

[0024] And by appropriately setting the width and depth of the recess 12, the leakage electric field indicated by the arrow A2 and the reflected electric field indicated by the arrow A4 resonate between the first transmission path 11 and the recess 12. Also, on the part of the recess 12 on the side opposite to the first transmission path 11, the leakage electric field indicated by the arrow A2 and the reflected electric field indicated by the arrow A5 cancel each other out. As a result, as shown in FIG. 5, the gap S is blocked by a wall, and an electric field distribution close to a state where a recess is formed in this wall is obtained. In this way, the leakage electric field from the gap S can be reduced.

[0025] As shown in FIG. 6, the leakage electric field from the first transmission path 11 is distributed such that the equiphase surfaces spread concentrically from the centers of the two long sides of the rectangle that constitutes the opening shape of the first transmission path 11. And this leakage electric field takes a maximum value on the straight line L1 and a minimum value on the straight line L2. Therefore, by setting a < L so that the periphery of the long side of the rectangle is covered by the recess 12 and arranging the recess 12 on both sides in the y direction with respect to the first transmission path 11, the leakage electric field can be efficiently reduced.

[0026] Assuming the electric field inside the first transmission path 11 is E, the electric field E takes a maximum value E 0 at the center in the x direction as shown in FIG. 7. Also, the electric field E has a symmetric distribution with respect to the straight line L1 and decreases as it approaches both ends in the x direction of the first transmission path 11. Corresponding to such an electric field distribution, it is desirable to set the width L so that the shape of the recess 12 is line-symmetric with respect to the straight line L1. Note that the width L is preferably set so as to cover more than half of the leakage electric field.

[0027] A method of estimating the leakage electric field from the electric field distribution in the first transmission line 11 and setting the range of arrangement of the recessed portion 12 will be described below. The electric field intensity E of the TE01 mode is expressed by the following formula 1 according to Maxwell's equations.

[0028]

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[0029]

number

[0030]

number

[0031]

number

[0032] Figure 8 shows the transmission loss A when L / a is changed. loss From Fig. 8, for example, the transmission loss A loss It can be seen that, to make the difference less than -0.1 dB, L / a=0.75, that is, the width L must be greater than 75% of the width a. For example, when the first transmission member 10 is made of a WR-12 waveguide, a=3.1 mm, and therefore the length L of the recess 12 must be 2.325 mm.

[0033] The width w and depth d of the recess 12 will be described. The wavelength of the electromagnetic wave transmitted by the first transmission line 11 is λ and the frequency is f. The transmission loss of the transmission device is A. loss The inventors performed a simulation with f=76.5 GHz and varying the width w and depth d, and obtained the transmission loss A loss Figure 9 shows the analysis results from this simulation. Figure 9 shows the analysis results in the range from d = 0 to d / λ = 1.25, i.e., d = 1.25λ ≒ 5 mm. Figure 9 also shows the analysis results for w = 0.2 mm, 0.12 mm, 0.8 mm, 1.2 mm, and 1.5 mm, i.e., for w = 0.051λ, 0.1275λ, 0.204λ, 0.306λ, and 0.3825λ.

[0034] If N is an integer equal to or greater than 0, then as shown in Figure 9, when the depth d is approximately λ / 4+N λ / 2, the transmission loss A loss When the depth d is N λ / 2, the transmission loss A loss This is reasonable in principle because of the periodicity of electromagnetic waves. However, since performance increases slightly by widening the width w, it is not necessarily the case that the transmission loss A is greater when d=λ / 4+N λ / 2. loss Considering the width w, the transmission loss A is minimized by setting the depth d to λ / 4+N λ / 2 or more and (N+1)λ / 2 or less. loss It is possible to reduce the depth d. Note that the depth d may be outside this range. For example, when it is desired to minimize the structure due to processing constraints, d=0.2λ or d≒0.2λ may be used.

[0035] The opening shape of the recess 12 will be described. For the above-mentioned distribution of the leakage electric field, if the recess 12 is extended in a straight line parallel to the x-direction as shown in Fig. 10, the angle between the equiphase surface of the electric field and the extension direction of the recess 12 becomes large in a place away from the straight line L1 such as the region R1. This increases the shift between the phase of the reflected electric field and the phase that can efficiently cancel the leakage electric field, which may reduce the leakage electric field suppression performance.

[0036] In contrast, by forming the opening shape of the recess 12 in an arc shape as in this embodiment, the opening shape of the recess 12 follows the electric field distribution, and the leakage electric field suppression performance can be improved.

[0037] The curvature of the arc L3 will be described. It is desirable to set the curvature of the arc L3 so as to follow the distribution shape of the equal power of the leakage electric field. The equal power here is synonymous with equal phase when material and spatial attenuation are not considered. As shown by the dashed lines L4, L5, and L6 in FIG. 11, the equal phase surface of the leakage electric field has a large curvature in the vicinity of the first transmission line 11 due to the influence of the corners and straight edges of the first transmission line 11. The curvature of the equal phase surface decreases as it moves away from the first transmission line 11, and converges to a perfect circle centered on the center P1. It is desirable to set the curvature of the recess 12 taking this into consideration.

[0038] For example, when the transmission device is housed in an integrated circuit such as a radar, it is desirable to reduce the size of the transmission device for mounting purposes, and therefore the recess 12 is disposed near the long side of the first transmission line 11. In this case, it is desirable to make the curvature of the arc L3 large. On the other hand, when the recess 12 is formed at a location far away from the first transmission line 11, it is desirable to make the curvature of the arc L3 small.

[0039] The position of the center P2 will be described. The dashed lines L7 to L15 in FIG. 12 are concentric circles centered on the center P1. In the vicinity of the first transmission line 11, the difference in shape between the equiphase surface of the leakage electric field and the concentric circles becomes large, so if the center P2 is aligned with the center P1, the difference in shape between the equiphase surface of the leakage electric field and the recess 12 becomes large, and there is a risk of the leakage electric field suppression performance being degraded. For example, in FIG. 12, the difference in shape between the equiphase surface and the recess 12 becomes large in the region R2 in the vicinity of the first transmission line 11 and in the region R3 that is farther from the first transmission line 11 and the straight line L1 than the region R2.

[0040] On the other hand, when the center of the concentric circles is moved from the center P1 in the y direction as shown in FIG. 13, the difference between the shape of the equiphase surface of the electric field and the concentric circles becomes smaller. FIG. 13 shows the electric field distribution when the first transmission member 10 is made of a WR-12 waveguide according to the EIA standard, and the center P2 is offset from the center P1 in the y direction to form the recess 12. For example, in FIG. 13, in the region R4 away from the straight line L1, the difference between the shape of the equiphase surface of the leakage electric field and the recess 12 becomes smaller. In this way, by placing the center P2 at a position different from the center P1, the difference between the shape of the equiphase surface of the leakage electric field and the recess 12 becomes smaller, and the leakage electric field suppression performance can be further improved.

[0041] Note that if the distance db between the centers P1 and P2 is too large, the recess 12 will not cover the corners of the first transmission line 11, which may result in a decrease in the leakage electric field suppression performance, and therefore it is desirable to make the distance db smaller to some extent. For example, when the first transmission member 10 is made of a WR-12 waveguide and the frequency f is 60 GHz to 90 GHz, it is desirable to set the distance db to 0.6 mm to 1.0 mm, that is, within ±0.2 mm in the y direction with respect to the center of the long side of the first transmission line 11.

[0042] However, this is not the case when the center P2 is offset from the center P1 in the opposite direction to the recess 12. That is, as shown in Fig. 14, when the center P2 of the arc L3 of the recess 12a is located on the same side as the recess 12b with respect to the first transmission line 11, the distance db can be made larger. For example, when the first transmission member 10 is formed of a WR-12 waveguide as described above, the distance db can be made larger than 1.0 mm.

[0043] Even when the center P2 coincides with the center P1, the opening shape of the recess 12 can be an elliptical arc shape, so that the recess 12 can be shaped along the equiphase surface of the leakage electric field, and the leakage electric field suppression performance can be further improved. For example, in FIG. 15, a plurality of ellipses having different lengths of axes in the x direction centered on the center P1 are shown by dashed lines. By forming the recess 12 along the ellipse shown by dashed line L16 among the plurality of ellipses, the opening shape of the recess 12 can be shaped along the equiphase surface of the leakage electric field.

[0044] The central angle θ and the transmission loss A when the center P2 is offset onto the long side of the first transmission line 11 and the radius r is a / 2. loss The relationship between the transmission loss and the loss It can be seen that if it is desired to make the difference less than −0.1 dB, the central angle θ needs to be approximately 150° or more.

[0045] Figure 17 shows the relationship between frequency f and transmission loss A loss 17 shows the results of a simulation in which the relationship between the above and the above is examined. In this simulation, the dimensions of the first transmission member 10 and the second transmission member 20 were set as follows: Lw=7 mm, aw=6 mm, bw=6 mm, a=3.1 mm, b=1.55 mm, δ=0.1 mm, d=1.4 mm, w=0.8 mm, r=1.55 mm, θ=150°, and db=0.8 mm. The solid and dashed lines in FIG. 17 show the results of a simulation in which the opening shape of the recess 12 is arc-shaped and linear, respectively.

[0046] As shown in FIG. 17, in the high frequency band used in millimeter wave radar, specifically, 65 GHz to 90 GHz, the transmission loss A loss In addition, by making the opening shape of the recess 12 arc-shaped, the transmission loss was reduced compared to when the opening shape was linear. Aloss was able to reduce.

[0047] As described above, in this embodiment, the first transmission member 10 has the recess 12 that opens at a location on the surface 10a away from the first transmission line 11, so that the leakage electric field from the gap S is cancelled by the reflected electric field from the recess 12, thereby reducing the transmission loss. For example, when electromagnetic waves are transmitted between a board and an antenna by the transmission device of this embodiment, the power of the board can be supplied to the antenna with low loss.

[0048] Moreover, in this embodiment, the transmission loss can be reduced simply by forming the recess 12 in the first transmission member 10, and there is no need for complex processing of the first transmission member 10, making it easy to manufacture the transmission device. Also, the size of the first transmission member 10 can be prevented from increasing.

[0049] Furthermore, according to the above embodiment, the following effects can be obtained.

[0050] (1) The first transmission line 11 is configured to transmit electromagnetic waves in the fundamental mode, which enables highly efficient electromagnetic wave transmission in the fundamental mode.

[0051] (2) The recess 12 is formed along an equiphase surface of the electric field spreading from the first transmission line 11. This makes it possible to efficiently cancel out the leakage electric field.

[0052] (3) The recesses 12 are formed on both sides of the first transmission line 11. This makes it possible to cancel out the leakage electric field to a greater extent than in the case where the recesses 12 are formed on only one side of the first transmission line 11.

[0053] (4) The depth d is set to be equal to or greater than λ / 4+N·λ / 2 and equal to or less than (N+1)λ / 2. This allows the leakage electric field to be efficiently cancelled out by the reflected electric field from the recess 12. For example, when the depth d is set to λ / 4+N·λ / 2, the time required to form the recess 12 can be shortened and the leakage electric field can be efficiently cancelled out.

[0054] (5) The opening shape on the surface 10a of the first transmission line 11 has a longitudinal direction and a lateral direction perpendicular to each other, and the opening shape on the surface 10a of the recess 12 is symmetrical with respect to a straight line L1 that passes through the center P1 and is parallel to the lateral direction. This reduces the difference between the equiphase surface of the leakage electric field and the shape of the recess 12, thereby further improving the leakage electric field suppression performance.

[0055] (6) The opening shape of the recess 12 on the surface 10a is an arc shape. This allows the recess 12 to have a shape that matches the distribution of the leakage electric field, thereby improving the leakage electric field suppression performance.

[0056] (7) The opening shape on one surface 10a of the first transmission line 11 has a longitudinal direction and a lateral direction that are perpendicular to each other, and the center P2 of the arc L3 is located on a straight line L1 that passes through the center P1 and is parallel to the lateral direction. By locating the center P2 in this way and setting the width L so that the shape of the recess 12 is linearly symmetric with respect to the straight line L1, the difference between the equiphase surface of the leakage electric field and the shape of the recess 12 is reduced, and the leakage electric field suppression performance can be further improved.

[0057] (8) The center P2 is located at a position different from the center P1. This reduces the difference between the equiphase surface of the leakage electric field and the shape of the recess 12, thereby further improving the leakage electric field suppression performance.

[0058] Second embodiment The second embodiment will be described. This embodiment is the same as the first embodiment except that the number of recesses 12 is changed from that of the first embodiment, and therefore only the differences from the first embodiment will be described.

[0059] In this embodiment, a plurality of recesses 12 are formed on one side and the other side in the y direction of the first transmission line 11. The recesses 12 formed on one side in the y direction of the first transmission line 11 have a greater width in the x direction as the recesses 12 are farther away from the center P1. Similarly, the recesses 12 formed on the other side in the y direction of the first transmission line 11 have a greater width in the x direction as the recesses 12 are farther away from the center P1.

[0060] 18, a recess 12a and a recess 12c opening at a location farther than recess 12a in the first transmission path 11 are formed on one side in the y direction with respect to the first transmission path 11. Also, a recess 12b and a recess 12d opening at a location farther than recess 12a in the first transmission path 11 are formed on one side in the y direction with respect to the first transmission path 11. That is, two recesses 12 are formed on each side in the y direction with respect to the first transmission path 11.

[0061] Recess 12c has a larger width in the x direction than recess 12a and opens in an arc shape to cover recess 12a from one side in the y direction. Recess 12d has a larger width in the x direction than recess 12b and opens in an arc shape to cover recess 12b from the other side in the y direction.

[0062] This embodiment has the same configuration and operation as the first embodiment, and therefore can obtain the same effects as the first embodiment.

[0063] Furthermore, according to the above embodiment, the following effects can be obtained.

[0064] (1) A plurality of recesses 12 are formed on one side of the first transmission line 11, and the width of the recesses 12 increases as the distance from the center P1 increases. This allows the electric field spreading concentrically to be covered, and the leakage electric field to be efficiently reduced.

[0065] Third embodiment A third embodiment will be described. This embodiment is different from the first embodiment in the configuration of the second transmission member 20, and other aspects are the same as those of the first embodiment, so only the differences from the first embodiment will be described.

[0066] As shown in Fig. 19, the second transmission member 20 of this embodiment has recesses 22 formed therein. The recesses 22 have the same configuration as the recesses 12. That is, the recesses 22 are formed on both sides of the second transmission path 21 in the y direction, and open in an arc shape at a location on the other surface 20b away from the second transmission path 21. The two recesses 22 are shaped to be line-symmetrical with respect to a line that passes through the center of the second transmission path 21 and is parallel to the y direction. The two recesses 22 are also arranged to be line-symmetrical with respect to a line that passes through the center of the second transmission path 21 and is parallel to the x direction.

[0067] By forming the recess 22 in the second transmission member 20, the leakage electric field from the gap S is cancelled by the reflected electric field at the recess 22, so that the transmission loss can be further reduced.

[0068] This embodiment has the same configuration and operation as the first embodiment, and therefore can obtain the same effects as the first embodiment.

[0069] (Fourth embodiment) A fourth embodiment will be described. This embodiment is different from the first embodiment in the configuration of the second transmission member 20, and other aspects are the same as those of the first embodiment, so only the differences from the first embodiment will be described.

[0070] As shown in Fig. 20, the second transmission member 20 of this embodiment is composed of a substrate. This substrate is a dielectric substrate on which an RF (Radio Frequency) circuit is formed, which is used in wireless devices such as radars and communication devices, and the second transmission line 21 is a microstrip line formed on the substrate. Note that, although there are various architectures for wireless device RF circuits, such as BGA (Ball Grid Array) and LiP (Launcher In Package), this embodiment is applicable to any of them.

[0071] This embodiment has the same configuration and operation as the first embodiment, and therefore can obtain the same effects as the first embodiment.

[0072] Fifth embodiment A fifth embodiment will be described. This embodiment is different from the first embodiment in the configuration of the second transmission member 20, and other aspects are the same as those of the first embodiment, so only the differences from the first embodiment will be described.

[0073] 21, the second transmission member 20 of this embodiment is an antenna. For example, the second transmission member 20 is a horn antenna, and a passage formed inside a truncated pyramidal member is the second transmission path 21.

[0074] This embodiment has the same configuration and operation as the first embodiment, and therefore can obtain the same effects as the first embodiment.

[0075] Sixth embodiment A sixth embodiment will be described. This embodiment is similar to the first embodiment except that the configuration of the first transmission member 10 is changed from that of the first embodiment, and therefore only the differences from the first embodiment will be described.

[0076] 22, the first transmission member 10 of the present embodiment is composed of a rectangular prism-shaped main body 13 and a connection portion 14 connected to the second transmission member, and the recess 12 is formed in the connection portion 14. In the present embodiment, the surface of the connection portion 14 that faces the second transmission member 20 is set as surface 10a, and the first transmission path 11 is composed of a portion that penetrates the main body 13 and a portion that penetrates the connection portion 14.

[0077] In addition, in Figure 22, recess 12 penetrates connection portion 14 and the bottom surface of recess 12 is formed by the surface of main body portion 13, but recess 12 may be formed to a depth that reaches halfway through connection portion 14.

[0078] Even if the portion of the surface of the main body 13 facing the second transmission member 20, away from the first transmission path 11, is made flat, the leakage electric field can be reduced by attaching a connection portion 14 having a recess 12 formed therein.

[0079] This embodiment has the same configuration and operation as the first embodiment, and therefore can obtain the same effects as the first embodiment.

[0080] (Other embodiments) The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate. The above-described embodiments are not unrelated to each other, and can be combined as appropriate, except when the combination is clearly impossible. In the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except when they are specifically stated to be essential or when they are clearly considered to be essential in principle. In the above-described embodiments, when the numbers, values, amounts, ranges, etc. of the components of the embodiments are mentioned, they are not limited to the specific numbers, except when they are specifically stated to be essential or when they are clearly limited to a specific number in principle. In the above-described embodiments, when the shapes, positional relationships, etc. of the components are mentioned, they are not limited to the shapes, positional relationships, etc., except when they are specifically stated to be essential or when they are clearly limited to a specific shape, positional relationship, etc. in principle.

[0081] The opening shape of the first transmission path 11 may be a shape different from that of the first embodiment. For example, as shown in FIG. 23, the opening shape of the first transmission path 11 may be a rectangle with rounded corners. Also, as shown in FIG. 24, the opening shape of the first transmission path 11 may be an H-shape composed of a rectangle extending in the x direction and a rectangle extending from both ends of the rectangle to both sides in the y direction. Also, the opening shape of the second transmission path 21 may be a shape different from that of the first embodiment. For example, the opening shape of the second transmission path 21 may be a shape similar to the opening shape of the first transmission path 11 shown in FIG. 23 and FIG. 24.

[0082] The recess 12 may have an opening shape different from that of the first embodiment. For example, the opening shape of the recess 12 may be linear. Even if the opening shape of the recess 12 is linear, the transmission loss A may be smaller than that shown in FIG. 17 by appropriately setting the width w, depth d, width L, etc. loss can be reduced to less than 0.1 dB. As shown in FIG. 25, the opening shape of the recess 12 may be L-shaped. As shown in FIG. 26, the opening shape of the recess 12 may be U-shaped. The end of the opening shape of the recess 12 may be bent. The end of the opening shape of the recess 12 may be uneven. The ends of the opening shapes of the two recesses 12 may be connected to each other. For example, as shown in FIG. 27, the opening shape of the recess 12 may be circumferential. As shown in FIG. 28, the opening shape of the recess 12 may be rectangular frame-shaped.

[0083] The recesses 12 may be formed only on one side in the y direction with respect to the first transmission line 11. In the above second embodiment, two recesses 12 are formed on each side of the first transmission line 11, but three or more recesses 12 may be formed on both sides or one side of the first transmission line 11.

[0084] In the third to sixth embodiments, a plurality of recesses 12 may be formed on both sides of the first transmission path 11, similar to the second embodiment. As shown in FIG. 29, in the fourth embodiment, a recess 22 may be formed, similar to the third embodiment. In the fifth and sixth embodiments, in the fourth embodiment, a recess 22 may be formed, similar to the third embodiment. In the sixth embodiment, the second transmission member 20 may be a substrate, similar to the fourth embodiment. In the sixth embodiment, the second transmission member 20 may be an antenna, similar to the fifth embodiment.

[0085] (In view of the present disclosure) [First viewpoint] A transmission device for transmitting electromagnetic waves, a first transmission member (10) in which a first transmission path (11) is formed; a second transmission member (20) in which a second transmission path (21) is formed, The first transmission path is a passage that opens to one surface (10a) of the first transmission member, the first transmission member and the second transmission member are disposed with a gap therebetween so that the second transmission path faces the one surface, The first transmission member has a recess (12) formed in the one surface, the recess (12) opening at a location away from the first transmission path. [Second viewpoint] The transmission device according to the first aspect, wherein the first transmission line is configured to transmit electromagnetic waves in a fundamental mode. [Third Perspective] The transmission device according to the first or second aspect, wherein the recess is formed along an equiphase surface of an electric field spreading from the first transmission path as a center. [Fourth viewpoint] The transmission device according to any one of the first to third aspects, wherein the recesses are formed on both sides of the first transmission line. [Fifth viewpoint] The recessed portion is formed in plurality on one side of the first transmission line, The transmission device according to any one of the first to fourth aspects, wherein the recesses have a width greater as the recesses are spaced farther from the center of the first transmission line. [Sixth viewpoint] The transmission device according to any one of the first to fifth aspects, wherein the recess is open to a predetermined width on the one surface. [Seventh viewpoint] The transmission device according to any one of the first to sixth aspects, wherein the recess is formed to a predetermined depth in a normal direction of the one surface. [Eighth viewpoint] The wavelength of the electromagnetic wave transmitted by the first transmission line is λ, Let N be an integer greater than or equal to 0. The transmission device according to any one of the first to seventh aspects, wherein the depth of the recess is equal to or greater than λ / 4+N·λ / 2 and equal to or less than (N+1)λ / 2. [Ninth viewpoint] The transmission device according to an eighth aspect, wherein the recess has a depth of λ / 4+N·λ / 2. [10th viewpoint] an opening shape on the one surface of the first transmission line has a longitudinal direction and a lateral direction which are perpendicular to each other; The transmission device according to any one of the first to ninth aspects, wherein the opening shape on the one surface of the recess is symmetrical with respect to a straight line that passes through the center of the opening shape of the first transmission line and is parallel to the short side direction. [Eleventh viewpoint] The transmission device according to any one of the first to tenth aspects, wherein an opening shape of the recess on the one surface is arc-shaped. [12th viewpoint] an opening shape on the one surface of the first transmission line has a longitudinal direction and a lateral direction which are perpendicular to each other; The transmission device according to an eleventh aspect, wherein the center of the arc constituting the opening shape of the recess is disposed on a straight line that passes through the center of the opening shape of the first transmission line and is parallel to the short side direction. [13th viewpoint] The transmission device according to a twelfth aspect, wherein a center of an arc constituting an opening shape of the recess is at a position different from a center of the first transmission line. [Explanation of symbols]

[0086] 10 First transmission member 11 First transmission line 12 Recess 20 Second transmission member 21 Second transmission line

Claims

1. A transmission device for transmitting electromagnetic waves, a first transmission member (10) having a first transmission path (11) formed therein; a second transmission member (20) in which a second transmission path (21) is formed, The first transmission path is a passage that opens to one surface (10a) of the first transmission member, the first transmission member and the second transmission member are disposed with a gap therebetween so that the second transmission path faces the one surface, The first transmission member has a recess (12) formed in the one surface, the recess opening at a location away from the first transmission path.

2. 2. The transmission device according to claim 1, wherein the first transmission line is configured to transmit electromagnetic waves in a fundamental mode.

3. The transmission device according to claim 1 , wherein the recess is formed along an equiphase surface of an electric field spreading from the first transmission path.

4. The transmission device according to claim 1 , wherein the recesses are formed on both sides of the first transmission line.

5. The recessed portion is formed in plurality on one side of the first transmission line, The transmission device according to claim 1 , wherein the recesses have a width greater as the recesses are spaced farther from the center of the first transmission line.

6. The transmission device according to claim 1 , wherein the recess is open to a predetermined width on the one surface.

7. The transmission device according to claim 1 , wherein the recess is formed to a predetermined depth in a normal direction of the one surface.

8. The wavelength of the electromagnetic wave transmitted by the first transmission line is λ, N is an integer equal to or greater than 0, 2. The transmission device according to claim 1, wherein the depth of the recess is set to be equal to or greater than λ / 4+N·λ / 2 and equal to or less than (N+1)λ / 2.

9. 9. The transmission device according to claim 8, wherein the depth of the recess is λ / 4+N·λ / 2.

10. an opening shape on the one surface of the first transmission line has a longitudinal direction and a lateral direction which are perpendicular to each other, The transmission device according to claim 1 , wherein an opening shape of the recess on the one surface is symmetrical with respect to a straight line that passes through a center of the opening shape of the first transmission line and is parallel to the short side direction.

11. The transmission device according to claim 1 , wherein an opening shape of the recess on the one surface is arc-shaped.

12. an opening shape on the one surface of the first transmission line has a longitudinal direction and a lateral direction which are perpendicular to each other, The transmission device according to claim 11 , wherein a center of an arc constituting the opening shape of the recess is disposed on a straight line that passes through a center of the opening shape of the first transmission line and is parallel to the short side direction.

13. The transmission device according to claim 12 , wherein a center of the arc that defines the opening shape of the recess is at a position different from a center of the first transmission line.

Images