JP6369394B2 - Transmission line-waveguide converter - Google Patents

Description

  The present invention relates to a transmission line-waveguide converter for connecting a transmission line such as a microstrip line and a waveguide, for example.

Signals are transmitted between a waveguide and a transmission line on a substrate in a millimeter wave radar used in a vehicle sensor used in ITS (Intelligent Transport Systems) and an in-vehicle sensor such as an automobile. For this purpose, a transmission line-waveguide converter is used.
For example, Patent Document 1 discloses a transmission line-waveguide converter configured by a waveguide and a dielectric substrate provided with an antenna disposed in the waveguide.

JP 2007-214777 A

  The transmission line-waveguide converter has a wider band including the use frequency band in order to ensure the required performance required in the use frequency band in which the transmission line-waveguide converter is used. It is a common practice to design for the required performance. This is because by ensuring the required performance in a wider band than the used frequency band, it is possible to absorb variations caused by manufacturing errors and the like.

  However, even if designed as described above, the transmission line-waveguide converter is a dielectric substrate, a waveguide mounted on the dielectric substrate, a terminator called a back short circuit that terminates the waveguide, etc. Because it is manufactured by combining many parts, the processing accuracy of each part and variations caused by the processing method affect the performance of the transmission line-waveguide converter, and the required performance in a wide band cannot be secured. As a result, it is a factor that deteriorates the manufacturing yield.

  In order to suppress the variation associated with the machining of each part, it may be possible to select a more accurate machining method to machine each part or to perform additional machining on the part, but this increases the time and cost required for manufacturing. This is not preferable because it leads to the conversion.

  In particular, the back short is formed with a rectangular hole corresponding to the opening of the rectangular waveguide. The back short and the waveguide are provided so that the hole and the opening coincide with each other with the dielectric substrate interposed. Here, since the back short is formed of a metal block or the like, a hole may be formed using an end mill or the like, while an opening of the waveguide may be formed by press molding or the like. is there. Thus, when a processing method differs between the said opening part and the said hole part, a gap may arise in both shape resulting from the difference in a processing method.

If a gap occurs in the shape between the opening and the hole, an unnecessary reflected wave is generated inside the waveguide, the required performance in a wide band cannot be ensured, and the manufacturing yield is deteriorated. It becomes.
On the other hand, in order to eliminate the gap in shape between the opening and the hole, it is necessary to change the machining method or perform additional machining, leading to an increase in cost.
For this reason, the technique which can ensure a required performance in a wide band, without eliminating the gap of a shape between the said opening part and the said hole part is desired.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a transmission line-waveguide converter capable of widening the bandwidth.

A transmission line-waveguide converter according to an embodiment includes a waveguide having a rectangular first opening, a termination portion that terminates the waveguide, and the waveguide and the termination portion. A substrate interposed therebetween, a transmission line provided on the substrate and electromagnetically coupled to the waveguide, and a ground conductor pattern provided on the front and back surfaces of the substrate, and the termination portion is And a rectangular second opening opened corresponding to the first opening of the waveguide, and four corners of the second opening are diagonally opposed to the second opening. In the first opening portion, the first opening portion has a curved shape that is smaller than the interval between diagonally opposed corners, and the ground conductor pattern is opened corresponding to the first opening portion. It has a rectangular pattern opening, and the four corners of the pattern opening are in the second opening. There is a kick four corners of the curved shape to the corresponding curved shape.
Thus, the rectangular shape here includes not only the case where the four corners are perpendicular, but also the case where the four corners are curved due to processing or design.

  According to the transmission line-waveguide converter of the present invention, it is possible to widen the bandwidth.

1 is an external view of a microstrip line-waveguide converter according to one embodiment. FIG. It is a figure when a microstripline-waveguide converter is seen from the back short side. (A) is the arrow sectional view of the AA line in FIG. 2, (b) is the arrow sectional view of the BB line in FIG. It is an external appearance perspective view when seeing a back short from the end face side. (A) is a figure which shows a part of end surface of a waveguide, (b) is a figure which shows a part of end surface of a back short circuit. It is a figure when the principal part of a converter is seen from the back short side, and is a figure which shows the shape of the pattern opening part of each ground pattern. (A) is an arrow sectional view of the CC line in FIG. 6, (b) is an arrow sectional view of the DD line in FIG. It is a graph which shows the passage characteristic of the converter concerning an example and a comparative example. It is a graph which shows the reflective characteristic of the converter which concerns on an Example and a comparative example.

[Description of Embodiment of Present Invention]
First, the contents of the embodiments of the present invention will be listed and described.
(1) A transmission line-waveguide converter according to an embodiment includes a waveguide having a rectangular first opening, a termination portion terminating the waveguide, the waveguide and the termination. A substrate interposed between the substrate, a transmission line provided on the substrate and electromagnetically coupled to the waveguide, and a ground conductor pattern provided on the front and back surfaces of the substrate, The terminal portion has a rectangular second opening that opens in correspondence with the first opening of the waveguide, and the four corners of the second opening are diagonally opposed to each other in the second opening. And the ground conductor pattern corresponds to the first opening portion, and the ground conductor pattern corresponds to the first opening portion so that the interval between the corners is smaller than the interval between the diagonally opposing corners in the first opening portion. A rectangular pattern opening that is open and has four corners of the pattern opening. There is a corresponding curve shapes at the four corners of the curved shape in section.

According to the transmission line-waveguide converter having the above-described configuration, the interval between the four corners of the second opening of the termination portion that is diagonally opposed in the second opening is the first opening. Since it is made into the curve shape which becomes smaller than the space | interval of the corners which are opposing on a diagonal line, a gap arises in an opening shape between a 2nd opening part and a 1st opening part. On the other hand, since the four corners of the pattern opening in the ground conductor pattern have a curved shape corresponding to the curved shape of the four corners in the second opening, a pseudo conductor wall is formed to form the waveguide and the termination. The grounding conductor pattern that connects the portions is smoothly connected to the second opening of the terminal portion, and the waveguide and the terminal portion can be connected.
In addition, a gap is formed in the shape of the four corners between the pattern opening of the ground conductor pattern and the first opening of the waveguide. However, the ground conductor pattern is a pseudo-connection between the waveguide and the terminal end. Since the conductive wall is configured, it is possible to suppress the occurrence of unnecessary reflection even if a gap occurs in the shape. For this reason, unnecessary reflection of a signal wave that may be generated inside the waveguide due to a geometric gap between the first opening of the waveguide and the second opening of the terminal end is prevented from being grounded. It can be suppressed by the pattern, and the influence on the performance of the transmission line-waveguide converter can be suppressed.
Thus, according to the transmission line-waveguide converter having the above-described configuration, even if there is a gap in shape between the first opening of the waveguide and the second opening of the termination, it is unnecessary. Reflection can be suppressed, and a wider band can be achieved.

(2) In the transmission line-waveguide converter, a plurality of the substrates may be provided, and the plurality of substrates and the ground conductor pattern may be alternately arranged and stacked on each other.
Even in this case, even if there is a gap in the shape between the first opening of the waveguide and the second opening of the terminal end, unnecessary reflection can be suppressed by the ground conductor pattern, and the bandwidth can be increased. can do.

(3) In the transmission line-waveguide converter, in the plurality of ground conductor patterns, the dimension of the pattern opening is the same as the dimension of the second opening, or the dimension of the second opening. In addition, it is preferable that the size of the pattern opening is set to gradually increase as the position of the pattern becomes farther from the terminal end.
In this case, even if there are dimensional variations in the pattern openings of the plurality of ground conductor patterns or variations in arrangement of the plurality of ground conductor patterns that occur during assembly, the positions of the pattern openings with respect to the second openings Deviation can be suppressed and broadband characteristics can be maintained.

[Details of the embodiment of the present invention]
Hereinafter, preferred embodiments will be described with reference to the drawings.
Note that at least a part of each embodiment described below may be arbitrarily combined.
[About overall configuration]
FIG. 1 is an external view of a microstrip line-waveguide converter according to an embodiment. In FIG. 1, a microstripline-waveguide converter 1 is interposed between a waveguide 2, a back short 3 that terminates the waveguide 2, and the waveguide 2 and the back short 3. A plurality of (three in the illustrated example) dielectric substrates (first dielectric substrate 4, second dielectric substrate 5, and third dielectric substrate 6).

  The microstrip line-waveguide converter 1 (hereinafter also simply referred to as the converter 1) is formed on a first dielectric substrate 4 disposed at a position closest to the back short 3 among a plurality of dielectric substrates. The signal from the microstrip line 9 is transmitted to the waveguide 2, and the signal from the waveguide 2 is transmitted to the microstrip line 9. The converter 1 of the present embodiment is used in a system that processes signals in a signal frequency band of 76 GHz to 81 GHz, and the frequency band used by the converter 1 is set to 76 GHz to 81 GHz. Is set.

The waveguide 2 is a quadrangular block member formed of aluminum alloy or the like, and a through hole 2a having a rectangular cross section is formed at the center. The through hole 2a is formed by, for example, press working using a punch or the like.
The through hole 2a passes through between the end face 2b and the end face 2c of the waveguide 2 at right angles, and opens at both end faces 2b and 2c. Therefore, the opening 2a1 in which the through hole 2a opens at the end surface 2b has a rectangular shape.
The waveguide 2 is for the W band, and the inner cross-sectional dimension of the through hole 2a is set, for example, to a long dimension of 2.54 mm and a short dimension of 1.27 mm.

The through hole 2a is composed of four inner wall surfaces 2d. Among these inner wall surfaces 2d, the inner corner 2e connecting the inner wall surfaces 2d adjacent to each other may have a curved surface shape with a radius of curvature of 0.15 mm or less, for example.
The inner corner 2e is not a curved surface shape because the inner wall surfaces 2d are orthogonal to each other by design, but may have a curved surface shape of 0.15 mm or less depending on processing accuracy.

  2 is a view of the microstripline-waveguide converter 1 as viewed from the back short 3 side, FIG. 3A is a cross-sectional view taken along line AA in FIG. b) is a cross-sectional view taken along line BB in FIG. In FIG. 2, the back short 3 is omitted for easy understanding. 3A and 3B exaggerate the thickness dimension of a conductor pattern such as a microstrip line provided on the first dielectric substrate 4 for easy understanding.

With reference to FIGS. 1 to 3, the plurality of dielectric substrates 4, 5, 6 are interposed between the end face 2 b of the waveguide 2 and the back short 3.
Each dielectric substrate 4 is a rectangular plate-like member that is made of, for example, an epoxy resin and matches the end surface 2b.

A ground pattern 10 (ground conductor pattern) is provided on the front and back surfaces of each dielectric substrate 4, 5, 6. As a result, the three dielectric substrates 4, 5, 6 and the ground pattern 10 are alternately arranged and stacked on each other.
Therefore, the ground pattern 10 is interposed between the first ground substrate 11 interposed between the first dielectric substrate 4 and the back short 3, and between the first dielectric substrate 4 and the second dielectric substrate 5. The second ground pattern 12, the third ground pattern 13 interposed between the second dielectric substrate 5 and the third dielectric substrate 6, the third dielectric substrate 6, the waveguide 2, and the like. And a fourth ground pattern 14 interposed therebetween.
The ground pattern 10 is a conductor pattern made of metal or the like and is grounded. The ground pattern 10 is formed in a rectangular shape that matches the front and back surfaces of each dielectric substrate 4.

  The first ground pattern 11 provided on the first surface 4 a of the first dielectric substrate 4 is in contact with the back short 3, and is disposed at a position closest to the back short 3 among the plurality of ground patterns 10.

  The first ground pattern 11 has a first pattern opening portion 11a opened corresponding to the opening portion 2a1 of the through hole 2a in the waveguide 2 when the first dielectric substrate 4 is viewed from the one surface 4a side. ing. The first pattern opening 11a has no conductor pattern in the range corresponding to the opening 2a1, and is opened by the absence of the conductor pattern.

  Further, the first ground pattern 11 has a non-patterned portion 15 having no conductor pattern from the first pattern opening 11 a to the outer edge side of the first dielectric substrate 4. The non-patterned portion 15 is formed in the range from the edge of the first pattern opening 11a to the outer edge of the first dielectric substrate 4 so as to connect the first pattern opening 11a and the outer edge of the first dielectric substrate 4. Has been.

  The non-patterned portion 15 is formed wider than the narrow portion 15a connected to the first pattern substrate 11 and the narrow portion 15a connected to the outer edge side of the first dielectric substrate 4 from the narrow portion 15a. And a wide portion 15b.

A microstrip line 9 is further provided on one surface 4 a of the first dielectric substrate 4.
The microstrip line 9 is a transmission line for transmitting a high-frequency signal such as a millimeter wave, and is formed in a straight line by a conductor such as metal. The microstrip line 9 is provided from the first pattern opening 11a to the non-patterned portion 15, and the tip thereof is disposed at the approximate center of the first pattern opening 11a. That is, the microstrip line 9 extends from the first pattern opening 11 a to the outer edge side of the first dielectric substrate 4.
The microstrip line 9 includes an antenna part 9 a disposed in the first pattern opening 11 a and a main body part 9 b extending from the antenna part 9 a to the outer edge of the first dielectric substrate 4. . The microstrip line 9 is electromagnetically coupled to the waveguide 2 by the antenna portion 9a.

The microstrip line 9 is formed along the longitudinal direction of the non-patterned portion 15. The non-patterned portion 15 is formed line-symmetrically with the microstrip line 9 as the center, and thereby, a constant interval is provided between the microstrip line 9 and the first ground pattern 11.
In this way, the non-patterned portion 15 guides the microstrip line 9 from the first pattern opening 11 a to the outer edge side of the first dielectric substrate 4.

  The narrow portion 15a of the non-patterned portion 15 has a positional relationship between the edge of the narrow portion 15a and the microstrip line 9, so that the loss as the microstrip line-waveguide converter 1 is minimized. It is formed as follows.

The second ground pattern 12 interposed between the first dielectric substrate 4 and the second dielectric substrate 5 is a second pattern opening that corresponds to the opening of the through hole 2 a in the waveguide 2. It has a portion 12a. The 2nd pattern opening part 12a has no conductor pattern in the range corresponding to the opening part 2a1, and it is opening because there is no conductor pattern.
The third ground pattern 13 interposed between the second dielectric substrate 5 and the third dielectric substrate 6 is opened corresponding to the opening of the through hole 2 a in the waveguide 2. It has a pattern opening 13a. The third pattern opening 13a has no conductor pattern in the range corresponding to the opening 2a1, and is opened by the absence of the conductor pattern.
Further, the fourth ground pattern 14 interposed between the third dielectric substrate 6 and the waveguide 2 also has an opening corresponding to the opening of the through hole 2a in the waveguide 2, like the pattern openings. The fourth pattern opening 14a is formed. The 4th pattern opening part 14a has no conductor pattern in the range corresponding to the opening part 2a1, and it is opening because there is no conductor pattern.

The ground patterns 11, 12, 13, 14 are connected to each other by a plurality of first vias 20 provided through the dielectric substrates 4, 5, 6.
The plurality of first vias 20 are members formed of a conductor such as metal and are provided through the dielectric substrates 4, 5, and 6. As shown in FIG. 2, the plurality of first vias 20 are arranged so as to surround the first pattern opening 11 a and the non-patterned portion 15 when the converter 1 is viewed from the back short 3 side.
As a result, the plurality of first vias 20 constitute a pseudo conductor wall that connects the waveguide 2 and the back short 3 together with the ground patterns 11, 12, 13, and 14, as will be described later.

The second ground pattern 12 and the third ground pattern 13 are also connected by a plurality of second vias 21.
The plurality of second vias 21 are members formed of a conductor such as metal, and are provided through only the second dielectric substrate 5. As shown in FIG. 2, the plurality of second vias 21 extend along the longitudinal direction on both sides of the microstrip line 9 so as to surround the microstrip line 9 when the converter 1 is viewed from the back short 3 side. Are arranged in a straight line in two rows.

Further, the third ground pattern 13 and the fourth ground pattern 14 are also connected by a plurality of third vias 25.
The plurality of third vias 25 are members formed of a conductor such as metal, and are provided through only the third dielectric substrate 6. As shown in FIG. 2, the plurality of third vias 25 are arranged along the longitudinal direction of the microstrip line 9 so as to be located immediately below the microstrip line 9 when the converter 1 is viewed from the back short 3 side. Are arranged in a straight line.

Of the plurality of second vias 21, the second via 21 formed at a position closest to the pattern opening side is a pseudo conductor that connects the waveguide 2 and the back short 3, as in the first via 20. Contributes to the construction of the wall. In addition, the other second via 21 reinforces the ground directly under the microstrip line 9.
Further, among the plurality of third vias 25, the third via 25 formed at a position closest to the pattern opening side is a pseudo-connecting the waveguide 2 and the back short 3, similar to the first via 20. This contributes to the construction of a simple conductor wall. Further, the other third via 25 reinforces the ground directly under the microstrip line 9.

The back short 3 is fixed to the first dielectric substrate 4 as a conductor wall that closes the opening of the through hole 2 a of the waveguide 2, and terminates the waveguide 2.
The back short 3 is a square block member formed of aluminum alloy or the like, and is arranged so as to cover a position corresponding to the opening 2a1 of the through hole 2a when the first dielectric substrate 4 is viewed from the one surface 4a side. Has been. A hole 3b is formed in the end surface 3a of the back short 3 facing the first dielectric substrate 4 side.

FIG. 4 is an external perspective view of the back short 3 when viewed from the end face 3a side.
4 and 1 to 3, the hole 3 b is a bottomed hole that is recessed in a rectangular cross section along the axis of the through hole 2 a of the waveguide 2. The opening 3b1 of the hole 3b that opens at the end face 3a is opened corresponding to the opening 2a1 of the through hole 2a. The hole 3b is formed by cutting using an end mill or the like, for example.
The hole 3b is composed of four inner wall surfaces 3d. Among the inner wall surfaces 3d, the inner wall surfaces 3d adjacent to each other are connected by a corner curved surface portion 3e. The radius of curvature of the corner curved surface portion 3e is set to 0.4 mm, for example.

  Further, in the back short 3, a relief portion 3 c is formed at a position corresponding to the non-patterned portion 15 of the first ground pattern 11, so that the back short 3 is not cut so as not to contact the microstrip line 9. .

  The back short 3 is solder-mounted with the end surface 3 a in contact with the first ground pattern 11. Thus, the back short 3 is grounded by being connected to the first ground pattern 11 and is fixed to the one surface 4 a side of the first dielectric substrate 4.

[About the pattern opening of each ground pattern]
FIG. 5A is a diagram showing a part of the end face 2 b of the waveguide 2.
The opening 2a1 of the through hole 2a is opened in a rectangular shape at the end surface 2b of the waveguide 2 as described above. The opening 2a1 of the waveguide 2 includes a linear edge 23 that is an edge of the inner wall surface 2d (FIG. 2), and corners 22 that form four corners of the opening 2a1.
As described above, the inner corner 2e (FIG. 2) of the through-hole 2a has a curved surface shape with a radius of curvature of 0.15 mm or less depending on processing accuracy, as described above. Therefore, the corner 22 of the opening 2a1 is also curved with a radius of curvature of 0.15 mm or less.

FIG. 5B is a diagram illustrating a part of the end surface 3 a of the back short 3. As described above, the opening 3b1 of the hole 3b of the back short 3 opens in a rectangular shape at the end face 3a of the back short 3. The opening 3b1 of the back short 3 is constituted by a linear edge 33 which is an edge of the inner wall surface 3d (FIG. 4) and corners 32 constituting the four corners of the opening 3b1.
As described above, the radius of curvature of the corner curved surface portions 3e provided at the four corners of the hole 3b is set to 0.4 mm. Therefore, the corner 32 of the opening 3b1 is also curved. The curvature radii of the corners 32 are set to 0.4 mm.

Further, the opening 3 b 1 of the back short 3 is set to have the same longitudinal and short dimensions as the opening 2 a 1 of the waveguide 2. The opening 3 b 1 of the back short 3 is provided at a position that substantially coincides with the opening 2 a 1 of the waveguide 2 in the longitudinal direction and the short direction.
When the shape of the opening 3b1 of the back short 3 and the shape of the opening 2a1 of the waveguide 2 are compared, the curved shapes of the corner 32 and the corner 22 are different.
The broken line in FIG. 5B indicates the opening 2a1 when the shape of the opening 2a1 of the through hole 2a is overlapped with the position of the longitudinal direction and the short direction with respect to the opening 3b1. ing.

In this way, the corner 32 of the opening 3b1 of the back short 3 has a curved shape with a larger radius of curvature than the corner 22 of the opening 2a1 of the waveguide 2, and is shown in FIG. As described above, the interval P between the corners 32 facing each other on the diagonal T in the opening 3b1 of the back short 3 is equal to the interval between the corners 22 facing each other on the diagonal T in the opening 2a1 of the through hole 2a. It is smaller than the interval of Q.
For this reason, the opening shape is different at the four corners between the opening 3b1 of the back short 3 and the opening 2a1 of the waveguide 2, and a partial gap is generated in the opening shape.
The interval P (interval Q) is a distance between points at which the opposing corner portions 32 (corner portions 22) intersect the diagonal T.

FIG. 6 is a diagram when the main part of the converter 1 is viewed from the back short 3 side, and is a diagram illustrating the shape of the pattern opening of each ground pattern. In FIG. 6, the back short 3 is omitted. In FIG. 6, the shape of the pattern opening that does not appear on the upper surface is also shown by a solid line for easy understanding. Further, the shape of the opening 2a1 of the waveguide 2 is indicated by a broken line.
In FIG. 6, the first pattern opening portion 11 a opening in a rectangular shape in the first ground pattern 11 has the same length L1 in the longitudinal direction and dimension S1 in the short direction as the opening portion 2 a 1 of the waveguide 2. Is set to Therefore, the dimension L1 in the longitudinal direction of the first pattern opening 11a is 2.54 mm, and the dimension S1 in the lateral direction is 1.27 mm.
Further, as shown in FIG. 6, the first pattern opening 11 a is provided at a position that substantially coincides with the opening 2 a 1 of the waveguide 2 in the longitudinal direction and the short direction.

On the other hand, the corner portions 41 constituting the four corners of the first pattern opening portion 11a have a curved shape with a curvature radius of 0.4 mm. That is, the corner 41 of the first pattern opening 11a has the same curved shape as the corner 32 of the opening 3b1 of the back short 3, and has a curved shape corresponding to the curved shape of the corner 32 of the opening 3b1. Has been.
Therefore, like the opening 3b1 of the back short 3, the opening shape of the first pattern opening 11a differs from the opening 2a1 of the waveguide 2 at the four corners, and there is a partial gap in the opening shape. Has occurred.

  The first pattern opening 11a has the same length L1 and short side dimension S1 as the opening 2a1 of the waveguide 2, and the corner 41 has the opening 3b1 of the back short 3. It has the same curved shape as the corner 32. Therefore, the first pattern opening 11a has the same opening shape and the same dimensions as the opening 3b1 of the back short 3.

In FIG. 6, the second pattern opening 12a, which is open in a rectangular shape in the second ground pattern 12, has a length L2 in the longitudinal direction and a dimension S2 in the short direction, the first pattern opening 11a (back short 3). Is set to be slightly larger than the opening 3b1). The dimension L2 in the longitudinal direction of the second pattern opening 12a is 2.58 mm, and the dimension S2 in the lateral direction is 1.31 mm.
The second pattern openings 12a are arranged with an interval of about 0.2 mm with respect to each side of the first pattern openings 11a so that the centers in the longitudinal direction and the short direction are substantially coincident with each other. Is provided.

  Further, the corners 42 constituting the four corners of the second pattern opening 12a are curved with a curvature radius of 0.4 mm. That is, the corner portion 42 of the second pattern opening 12a has the same curved shape as the corner 32 of the opening 3b1 of the back short 3, similarly to the corner 41 of the first pattern opening 11a, and the opening 3b1. It is set as the curve shape corresponding to the curve shape of the corner part 32.

In FIG. 6, the third pattern opening 13a of the third ground pattern 13 is set such that the longitudinal dimension L3 and the lateral dimension S3 are slightly larger than the second pattern opening 12a. . The dimension L3 in the longitudinal direction of the third pattern opening 13a is 2.62 mm, and the dimension S3 in the lateral direction is 1.35 mm.
The fourth pattern opening 14a of the fourth ground pattern 14 is set so that the longitudinal dimension L4 and the lateral dimension S4 are slightly larger than the third pattern opening 13a. The dimension L4 in the longitudinal direction of the fourth pattern opening 14a is 2.66 mm, and the dimension S3 in the lateral direction is 1.39 mm.

The third pattern opening 13a is disposed at an interval of about 0.2 mm with respect to each side of the second pattern opening 12a so that the centers in the longitudinal direction and the short direction are substantially coincident with each other. Is provided.
The 4th pattern opening part 14a is arrange | positioned at intervals of about 0.2 mm with respect to each side of the 3rd pattern opening part 13a, and it is so that the center of a mutual longitudinal direction and a transversal direction may mutually correspond. Is provided.

Further, the corners 43 constituting the four corners of the third pattern opening 13a are curved with a curvature radius of 0.4 mm. That is, the corner portion 42 of the second pattern opening 12a has the same curved shape as the corner 32 of the opening 3b1 of the back short 3, similarly to the corner 41 of the first pattern opening 11a, and the opening 3b1. It is set as the curve shape corresponding to the curve shape of the corner part 32.
Furthermore, the corners 44 constituting the four corners of the fourth pattern opening 14a are also curved with a radius of curvature of 0.4 mm, and have a curved shape corresponding to the curved shape of the corner 32 of the opening 3b1. ing.

FIG. 7A is a cross-sectional view taken along the line CC in FIG. In FIG. 7A, the dimensions and the like of each pattern opening are exaggerated for easy understanding.
As described above, the first pattern opening 11a has the same opening shape and the same size as the opening 3b1 of the back short 3, and the opening 3b1 of the back short 3 as shown in FIG. Are provided so as to substantially match.

Further, as described above, the longitudinal dimension and the lateral dimension of the pattern openings 12a, 13a, and 14a other than the first pattern opening 11a are the same as the longitudinal dimension and the short dimension of the opening 3b1 of the back short 3. It is set larger than the dimension in the hand direction.
Further, the longitudinal dimension and the lateral dimension of the pattern openings 11a, 12a, 13a, and 14a are gradually increased as the positions where the respective ground patterns 11, 12, 13, and 14 are disposed away from the back short circuit 3. It is set to be large.

That is, as shown in FIG. 7 (a), the fourth pattern opening 14a of the fourth ground pattern 14 disposed at the position farthest from the back short 3 among the ground patterns 12, 13, 14 is: Since the dimension L4 in the longitudinal direction and the dimension S4 in the lateral direction are set to be large, the opening area is the largest. Next, the opening area is gradually narrowed in the order of the third pattern opening 13a and the second pattern opening 12a.
That is, each pattern opening 11a, 12a, 13a, 14a has its opening area expanded in order from the opening 3b1 of the back short 3 toward the opening 2a1 of the waveguide 2.

  Further, as shown in FIG. 7 (a), there is a partial opening shape between the corner 32 in the opening 3b1 of the back short 3 and the corner 22 in the opening 2a1 of the waveguide 2. A step D occurs due to the gap.

FIG. 7B is a cross-sectional view taken along the line DD in FIG. 6 and shows a portion other than the corner 22 in the opening 2 a 1 of the waveguide 2. In FIG. 7B, the dimensions of the pattern openings and the like are exaggerated for easy understanding.
Also in this portion, the first pattern opening 11a has the same opening shape and the same size as the opening 3b1 of the back short 3, and therefore substantially coincides with the opening 3b1 of the back short 3.
On the other hand, there is no step between the corner 22 and the corner 32 between the opening 3b1 of the back short 3 and the opening 2a1 of the waveguide 2 as shown in FIG. .

As described above, the opening area of the fourth pattern opening portion 14a is formed to include the opening area of the third pattern opening portion 13a.
The third pattern opening 13a is formed in such a size that the opening area thereof includes the opening area of the second pattern opening 12a.
The opening area of the second pattern opening 12a is formed to include the opening area of the first pattern opening 11a.
As described above, the size of each pattern opening 11a, 12a, 13a, 14a gradually increases as the position of the pattern opening 11a, 12a, 13a, 14a moves away from the back short 3. ing.

  The converter 1 of the present embodiment includes a waveguide 2 having a rectangular opening 2a1 (first opening), a back short 3 (termination) that terminates the waveguide 2, a waveguide 2, Dielectric substrates 4, 5, 6 interposed between the back short 3 and a microstrip line 9 (transmission line) provided on each of the substrates 4, 5, 6 and electromagnetically coupled to the waveguide 2. And a ground pattern 10 provided on the front and back surfaces of each substrate 4, 5, 6, and the back short 3 is a rectangular opening 3 b 1 (corresponding to the opening 2 a 1 of the waveguide 2). The corners 32 of the opening 3b1 are diagonally opposed to each other in the opening 3b1 and the corners 32 are opposed to each other diagonally in the opening 2a1. The curve shape is smaller than the interval between 22 The pattern 10 has rectangular pattern openings 11a, 12a, 13a, and 14a that are opened at positions corresponding to the openings 2a1 of the waveguide 2, and corners of the pattern openings 11a, 12a, 13a, and 14a. 41, 42, 43, 44 have a curved shape corresponding to the curved shape of the corner 32 in the opening 3 b 1 of the back short 3.

  According to the converter 1 having the above-described configuration, the corners 32 of the opening 3b1 of the back short 3 are diagonally opposed to each other in the opening 3b1 so that the corners 32 face each other diagonally in the opening 2a1. Since the curved shape is smaller than the interval between the corner portions 22 being opened, a step D (see FIG. 7A) is formed in the opening shape between the opening 3b1 and the opening 2a1. A gap is created. On the other hand, the corners 41, 42, 43, 44 in the pattern openings 11 a, 12 a, 13 a, 14 a in each ground pattern 10 have a curved shape corresponding to the curved shape of the corner 32 in the opening 3 b 1 of the back short 3. Therefore, each ground pattern 10 that configures a pseudo conductor wall and connects the waveguide 2 and the back short 3 is smoothly connected to the opening 3b1 of the back short 3, and the waveguide 2 Back short 3 can be connected.

  In addition, gaps are formed in the shape of the four corners between the pattern openings 11a, 12a, 13a, and 14a of each ground pattern 10 and the opening 2a1 of the waveguide 2, but each ground pattern 10 has a wave guide. Since a pseudo conductor wall that connects the tube 2 and the back short 3 is formed, even if a gap occurs in the shape, unnecessary reflection does not occur remarkably. For this reason, unnecessary reflections of signal waves that may be generated inside the waveguide 2 due to the geometric gap between the opening 2a1 of the waveguide 2 and the opening 3b1 of the back short 3 are It can be suppressed by the ground pattern 10 and the influence on the performance of the converter 1 can be suppressed.

  Thus, according to the converter 1, even if there is a gap in the shape between the opening 2 a 1 of the waveguide 2 and the opening 3 b 1 of the back short 3, unnecessary reflection can be suppressed. Can be widened.

  Further, when there is a gap in shape between the opening 2a1 of the waveguide 2 and the opening 3b1 of the back short 3, for example, by performing additional processing on the hole 3b of the back short 3, It is possible to eliminate the gap, but this leads to an increase in cost. In this respect, according to the converter 1 of the present embodiment, unnecessary reflection can be suppressed without additional processing in the opening 3b1 of the back short 3, and as a result, the bandwidth can be increased while maintaining the cost. Is possible.

  Moreover, in the said embodiment, the 1st ground pattern 11 arrange | positioned in the position nearest to the back short 3 among several ground patterns 10 is the dimension of the longitudinal direction of a 1st pattern opening part 11a, and a transversal direction. The dimension is set to the same dimension as the longitudinal dimension and the lateral dimension of the opening 3 b 1 of the back short 3, and is arranged at a position closest to the back short 3 among the plurality of ground patterns 10. The ground patterns 12, 13, 14 other than the first ground pattern 11 have the longitudinal dimension and the lateral dimension of each pattern opening 12 a, 13 a, 14 a, the longitudinal dimension of the opening 3 b 1 of the back short 3. Each pattern opening is set to be larger than the dimension in the short-side direction, and as the position where it is arranged moves away from the back short 3. 2a, 13a, the longitudinal dimension and lateral dimension of 14a is set so as gradually increases.

  That is, the plurality of ground patterns 10 are arranged such that the size of each pattern opening 11a, 12a, 13a, 14a is the same as or larger than the opening 3b1 of the back short 3. As the position moves away from the back short 3, the sizes of the pattern openings 11a, 12a, 13a, and 14a are gradually increased.

  For this reason, even if there is a variation in dimensions in the pattern openings 11a, 12a, 13a, and 14a of each ground pattern 10 or a variation in arrangement between the ground patterns 10 that occurs during assembly, the pattern openings 11a, The positional shift of the back short 3 of 12a, 13a, 14a with respect to the opening 3b1 can be suppressed, and the broadband characteristics can be maintained.

In the present embodiment, the size of the first pattern opening 11a of the first ground pattern 11 is set to the same size as the opening 3b1 of the back short 3, but the size of the first pattern opening 11a is The opening 3b1 of the back short 3 may be slightly smaller.
As described above, the first ground pattern 11 is in contact with the back short 3 by being disposed at a position closest to the back short 3, and the back short 3 is solder-mounted.
Therefore, if the size of the first pattern opening 11a of the first ground pattern 11 is made slightly smaller than the opening 3b1 of the back short 3, even if a dimensional error due to processing accuracy occurs, the back short 3 The contact area between the end surface 3a and the first ground pattern 11 can be ensured as large as possible, and the back short circuit 3 can be more reliably grounded.
Note that the size of the first pattern opening 11a is determined based on the processing accuracy of the first pattern opening 11a and the processing accuracy of the opening 3b1 of the back short 3. It is set to a value that can be brought into contact with the pattern 11.

Moreover, in the said embodiment, the position where each ground pattern 11, 12, 13, 14 is arrange | positioned is the position of the longitudinal direction of a pattern opening part 11a, 12a, 13a, 14a, and the dimension of a transversal direction. In this example, the pattern openings 11a, 12a, 13a, and 14a are gradually increased in size as the distance from the back short 3 increases.
On the other hand, for example, the second pattern opening 12a may be made larger than the size of the first pattern opening 11a by increasing at least one of the longitudinal dimension and the lateral dimension. Good. Similarly, the third pattern opening portion 13a (fourth pattern opening portion 14a) is also increased by increasing at least one of the longitudinal dimension and the transverse dimension thereof, whereby the second pattern opening 12a (third pattern). It may be made larger than the size of the opening 13a).

[Evaluation test according to the embodiment]
Next, the evaluation test regarding the converter 1 according to the above embodiment, which was performed by the present inventor, will be described.
The present inventor obtained the transmission characteristics and the reflection characteristics of the converter 1 according to the above embodiment by computer simulation and analyzed, and compared and evaluated the characteristics.

  As a modeled configuration, the converter 1 shown in FIGS. 1 to 7 is employed. As described above, the converter 1 is set from 76 GHz to 81 GHz as a use frequency band. Therefore, the converter 1 needs to be set so that the attenuation is small between 76 GHz and 81 GHz and the reflection characteristics are good.

  The following two were prepared as examples. As Example 1, a converter 1 using a ground pattern 10 having a pattern opening formed with the dimensions shown in the above embodiment was employed. That is, the corner of each pattern opening of the converter 1 according to the first embodiment has the same curved shape as the corner 32 of the opening 3 b 1 of the back short 3. In addition, each pattern opening is set so that the opening region is expanded in order from the opening 3 b 1 of the back short 3 toward the opening 2 a 1 of the waveguide 2.

As Example 2, the converter 1 using the ground pattern 10 in which each pattern opening is set so that the size and shape of the opening 3b1 of the back short 3 are the same is employed. That is, the corner of each pattern opening of the converter 1 according to the second embodiment has the same curved shape as the corner 32 of the opening 3 b 1 of the back short 3.
Further, as a comparative example, a converter 1 using a ground pattern 10 in which each pattern opening is set so that the size and shape of the opening 2a1 of the waveguide 2 are the same is employed. That is, the corner of each pattern opening of the converter 1 according to the comparative example has a shape corresponding to the corner 22 of the opening 2 a 1 of the waveguide 2.

The dimensions of Example 1, Example 2, and Comparative Example are shown below.
Example 1: L1 = 2.54 mm, S1 = 1.27 mm, L2 = 2.58 mm, S2 = 1.31 mm, L3 = 2.62 mm, S3 = 1.35 mm, L4 = 2.66 mm, S4 = 1. 39 mm, radius of curvature of each corner 41, 42, 43, and 44 = 0.4 mm
Example 2: L1 = L2 = L3 = L4 = 2.54 mm, S1 = S2 = S3 = S4 = 1.27 mm, radius of curvature of each corner 41, 42, 43, and 44 = 0.4 mm
Comparative example: L1 = L2 = L3 = L4 = 2.54 mm, S1 = S2 = S3 = S4 = 1.27 mm, curvature radius of each corner 41, 42, 43, and 44 = 0.15 mm or less

FIG. 8 is a graph showing pass characteristics of the converters according to the example and the comparative example. In the figure, the horizontal axis represents the frequency (GHz) of the input signal, and the vertical axis represents the pass characteristic (S parameter S ₂₁ ) (dB).
In the figure, a diagram E1 (solid line) shows Example 1, a diagram E2 (one-dot chain line) shows Example 2, and a diagram C (broken line) shows a comparative example.

  In FIG. 8, in the comparative example, the value at the marker m1 where the frequency of the input signal is 76 GHz is −0.308 dB, and the value at the marker m2 where the frequency of the input signal is 81 GHz is −0.355 dB. In Example 2, the value at the marker m1 is −0.307 dB, which is substantially the same as the comparative example, but the value at the marker m2 is −0.330 dB, and the passing loss is reduced on the high frequency band side. It can be seen that a wider band is realized on a higher frequency side than the used frequency band.

  In Example 1, the value at the marker m1 is -0.268 dB, the value at the marker m2 is -0.332 dB, and the passage loss is reduced at both the markers m1 and m2 compared to the comparative example. It can be seen that widening is realized not only on the higher frequency side but also on the lower frequency side with respect to the used frequency band.

FIG. 9 is a graph showing the reflection characteristics of the converters according to Examples and Comparative Examples. In the figure, the horizontal axis represents the frequency (GHz) of the input signal, and the vertical axis represents the reflection characteristic (S parameter S ₁₁ ) (dB).
In the figure, a diagram E1 (solid line) shows Example 1, a diagram E2 (one-dot chain line) shows Example 2, and a diagram C (broken line) shows a comparative example.

  In FIG. 9, in the comparative example, the value at the marker m3 whose input signal frequency is 76 GHz is -19.663 dB, and the value at the marker m4 whose input signal frequency is 81 GHz is -18.537 dB. In Example 2, the value at the marker m3 is −19.672 dB, which is a small reduction compared to the comparative example, but the value at the marker m4 is −20.625 dB, and the value is greatly reduced on the high frequency band side. Thus, it can be seen that a wider band is realized on the higher frequency side than the used frequency band.

  In Example 1, the value at the marker m3 is −24.184 dB and the value at the marker m4 is −19.145 dB. Compared with the comparative example, the passage loss is reduced in both the markers m3 and m4. It can be seen that widening is realized not only on the higher frequency side but also on the lower frequency side with respect to the used frequency band.

  From the above results, it has been clarified that according to the converter 1 of the present embodiment, a wider band can be realized with respect to the used frequency band.

[Other Embodiments]
In the above-described embodiment, the case where a multilayer substrate is formed by using a plurality of dielectric substrates is illustrated, but a single-layer substrate using only one dielectric substrate may be used. In this case, a ground pattern is provided on the front and back surfaces of a single dielectric substrate. Furthermore, the corners of the pattern openings provided in these ground patterns are formed in a curved shape corresponding to the curved shape of the corner 32 in the opening 3 b 1 of the back short 3.
Even in the case where the converter is configured using such a single layer substrate, even if there is a gap in the shape between the opening 2a1 of the waveguide 2 and the opening 3b1 of the back short 3, it is unnecessary. Reflection can be suppressed and a wider band can be achieved.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Microstrip line-waveguide converter 2 Waveguide 2a Through-hole 2a1 Opening part 2b End surface 2c End surface 2d Inner wall surface 2e Inner corner 3 Back short 3a End surface 3b Hole part 3b1 Opening part 3c Escape part 3d Inner wall surface 3e Corner curved surface Portion 4 First dielectric substrate 4a One surface 5 Second dielectric substrate 6 Third dielectric substrate 9 Microstrip line 9a Antenna portion 9b Body portion 10 Ground pattern 11 First ground pattern 11a First pattern opening 12 Second ground pattern 12a Second pattern opening 13 Third ground pattern 13a Third pattern opening 14 Fourth ground pattern 14a Fourth pattern opening 15 No pattern portion 15a Narrow portion 15b Wide portion 20 First via 21 Second via 22 Corner 23 Edge 32 Corner 33 Edge 41 Corner 42 Corner 3 corners 44 corners

Claims (3)

A waveguide having a rectangular first opening;
A termination for terminating the waveguide;
A substrate interposed between the waveguide and the terminal end;
A transmission line provided on the substrate and electromagnetically coupled to the waveguide;
A grounding conductor pattern provided on the front and back surfaces of the substrate,
The terminal portion has a rectangular second opening that is opened corresponding to the first opening of the waveguide;
The four corners of the second opening are such that the interval between the diagonally opposing corners in the second opening is smaller than the interval between the diagonally opposing corners in the first opening. With a curved shape,
The grounding conductor pattern has a rectangular pattern opening opened corresponding to the first opening,
A transmission line-waveguide converter in which the four corners of the pattern opening have curved shapes corresponding to the curved shapes of the four corners of the second opening. The substrate is plural,
The transmission line-waveguide converter according to claim 1, wherein the plurality of substrates and the ground conductor patterns are alternately arranged and stacked on each other.   Among the plurality of ground conductor patterns, the ground conductor pattern other than the ground conductor pattern that is in contact with the termination portion by being disposed at a position closest to the termination portion has a size of the pattern opening, 3. The pattern opening is gradually increased in size as the second opening is the same as or larger than the second opening and the disposition position is further away from the terminal end. A transmission line-waveguide converter according to claim 1.

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