JP7215075B2 - Transmission line structure - Google Patents

Description

The present disclosure relates to transmission line structures.

Waveguides (such as hollow rectangular waveguides) are often used for inputs to very high frequency antennas such as millimeter wave antennas. Also, as an antenna for very high frequencies such as a millimeter wave antenna, a printed circuit board antenna is adopted because of its low cost. A microstrip line formed on a printed circuit board is often used to feed power to the printed circuit board antenna.

K. Seo, “Planar Microstrip-To-Waveguide Transition in Millimeter-Wave Band,” Advancement in Microstrip Antennas with RecentApplications, ed. A. Kishk, pp.249-277, 2013.[Retrieved on September 25, 2018] , Internet <URL: https://www.intechopen.com/books/advancement-in-microstrip-antennas-with-recent-applications>

Therefore, a transmission line for feeding power is composed of a waveguide and a microstrip line. As a result, a converter (waveguide-microstripline converter) is required to convert the mode between the waveguide and the microstripline.

In order to ensure the broadband performance of the antenna, the waveguide-microstrip line converter must also have broadband performance. For example, in millimeter-wave radar, the band is 1 GHz in the 76 GHz band, and 4 GHz in the 79 GHz band. Therefore, a broader bandwidth waveguide-to-microstripline converter is desirable. However, such broadening of the band is not easy.

Here, Non-Patent Document 1 discloses a structure for waveguide-microstrip line conversion in the millimeter wave band. In the structure disclosed in Non-Patent Document 1, a waveguide is connected to a printed circuit board on which microstrip lines are formed. In Non-Patent Document 1, waveguide-microstrip line conversion is realized by a metal component called a back short mounted on a printed circuit board. However, the structure of Non-Patent Document 1 requires a component called a back short, which causes an increase in cost. Moreover, it is necessary to attach the back short to the printed circuit board, which complicates the manufacturing work.

The present inventors have found a novel transmission line structure suitable for realizing broadband waveguide-microstrip line conversion without using a component such as a back short.

An aspect of the present disclosure relates to a transmission line structure. The transmission line structure includes a first waveguide and a transformer waveguide provided on one end side of the first waveguide in the waveguide direction and having an H-plane narrower than the H-plane of the first waveguide. and a second waveguide connected to the transformer waveguide via a slit, having a lower impedance than the first waveguide, and extending in a direction intersecting the E-plane of the first waveguide.

According to the present disclosure, it is possible to obtain a transmission line structure that facilitates ensuring broadband performance.

FIG. 1 is a plan view of an antenna device. FIG. 2 is a cross-sectional view of the antenna device. FIG. 3 is a cross-sectional view taken along line III-III of FIG. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. FIG. 5 is a cross-sectional view taken along line VV of FIG. FIG. 6 is a sectional view taken along line VI-VI of FIG. FIG. 7 is a cross-sectional view of a modification of FIG. FIG. 8 is a cross-sectional view of the equivalent circuit of FIG. 9 is a cross-sectional view of a modification of FIG. 2. FIG. FIG. 10 is a plan view of the antenna device according to the second embodiment. FIG. 11 is a plan view of the antenna device according to the second embodiment. 4 is a polar chart showing simulation results of the first embodiment. It is a VSWR characteristic chart which shows the simulation result of 1st Embodiment. FIG. 14A is a polar chart of reflection characteristics without a stub in the third embodiment. FIG. 14B is a polar chart of reflection characteristics in the case of the third embodiment (with stub). FIG. 15A is a VSWR characteristic diagram of reflection characteristics without a stub in the third embodiment. FIG. 15B is a VSWR characteristic diagram of reflection characteristics in the case of the third embodiment (with stub). FIG. 16A is a pass characteristic diagram without a stub in the third embodiment. FIG. 16B is a pass characteristic diagram for the third embodiment (with stub).

[1. Outline of Embodiment]

(1) The transmission line structure of the embodiment includes a first waveguide and a transformer having an H-plane provided at one end in the waveguide direction of the first waveguide and narrower than the H-plane of the first waveguide. an impedance adjusting section including a waveguide; and a second waveguide connected to the transformer waveguide via a slit, having a lower impedance than the first waveguide, and extending in a direction intersecting the E-plane of the first waveguide. And prepare. According to this transmission line structure, since the first waveguide is converted into the second waveguide with low impedance, it becomes easy to ensure broadband performance when the second waveguide is connected to the microstrip line.

(2) The transmission line structure includes a microstrip line formed on a printed circuit board, a converter between the second waveguide and the microstrip line formed on the printed circuit board,
can be further provided. Preferably, the second waveguide is formed on the printed circuit board. In this case, it is easy to ensure broadband performance in the converter.

(3) Preferably, the transmission line structure further includes an antenna formed on the printed circuit board and fed by the microstrip line. In this case, an integral structure is obtained in which the second transmission line, the microstrip line, the transducer and the antenna are formed on the printed circuit board.

(4) Preferably, the second waveguide is a substrate integrated waveguide in which post walls are formed by a plurality of vias connecting the first conductor pattern and the second conductor pattern serving as a ground plane. In this case, a thin second waveguide with low impedance can be easily obtained.

(5) Preferably, the impedance adjusting section includes one or a plurality of impedance adjusting vias provided within a range surrounded by the plurality of vias forming the post walls in the substrate integrated waveguide. In this case, impedance adjustment becomes easy.

(6) The first conductor pattern has a pattern end that becomes the output end of the substrate integrated waveguide, and the center of the output end via closest to the pattern end among the plurality of vias forming the post wall. , the length to the pattern end is preferably 0.1 λg (λg is the wavelength in the substrate integrated waveguide) or less. In this case, it is possible to suppress the leakage path of the electromagnetic wave from the output end via to the pattern end.

(7) the first conductor pattern has a pattern end that becomes an output end of the substrate integrated waveguide;
It is preferable to have an output end via closest to the pattern end among the plurality of vias forming the post wall and a stub for short-circuiting between the pattern end. In this case, it is possible to suppress the leakage path from the output end via to the pattern end by short-circuiting from the output end via to the pattern end.

(8) Preferably, the stub is an open stub formed at a position for shorting between the output end via and the pattern end. In this case, it is possible to easily short-circuit from the output end via to the pattern end.

(9) When a stub is used to short the output end via to the pattern end, the length from the center of the output end via to the pattern end is 0.1λg (λg is the wavelength in the substrate integrated waveguide ). Even if the length from the output end via to the pattern end is long, the short circuit between the output end via and the pattern end suppresses the leakage path from the output end via to the pattern end. can.

(10) The impedance of the second waveguide is preferably 1/45 or more of the impedance of the first waveguide and 1/1.2 or less of the impedance of the first waveguide.

(11) Preferably, the impedance of the second waveguide is 1/20 or more of the impedance of the first waveguide.

(12) Preferably, the impedance of the second waveguide is 1/1.3 or less of the impedance of the first waveguide.

[2 Details of Embodiment]

[2.1 Antenna Device Having Transmission Line Structure According to First Embodiment]

1 to 6 show an antenna device 10 having a transmission line structure according to the first embodiment. The antenna device 10 is for millimeter wave radar, for example, and is used for receiving or transmitting electromagnetic waves. In the following description, as an example, the antenna device 10 is for 76.5 GHz (wavelength λ: 3.92 mm).

As shown in FIG. 2 , the antenna device 10 according to the embodiment includes a printed board 13 on which an antenna 30 is formed, and a waveguide block 11 attached to the printed board 13 . The antenna device 10 includes a transmission line 20 formed on a waveguide block 11 and a printed board 13 and an antenna 30 formed on the printed board 13 . The transmission line 20 of the embodiment comprises a first waveguide 40 , a transformer waveguide 51 , a slit 55 , a second waveguide 60 , a converter 70 and a microstripline 80 .

As shown in FIG. 2 , the printed circuit board 13 includes a first conductor pattern 15 , a second conductor pattern 17 and a dielectric base material 19 . The first conductor pattern 15 is provided on one side (upper side in FIG. 2) of the dielectric base material 19 . The second conductor pattern 17 is provided on the dielectric substrate 19 on the side opposite to the first conductor pattern 15 (lower side in FIG. 2). The second conductor pattern 17 is a ground plane.

As shown in FIG. 4, the second conductor pattern 17 is formed on the entire surface of the dielectric base material 19 opposite to the first conductor pattern 15 (excluding the range of the slit 55). In the following description, the dielectric base material 19 has, as an example, a dielectric constant εr of 3.2, a dielectric loss tangent tan δ of 0.001, and a substrate thickness of 0.127 mm.

As shown in FIG. 1, in the embodiment, the first conductor pattern 15 comprises a pattern 65 forming the second waveguide 60, a pattern forming the transducer (tapered portion) 70, and a microstrip line 80. and a pattern that configures the antenna 30 . As a result, the printed circuit board 13 of the embodiment integrally includes the second waveguide 60, the converter 70, the microstrip line 80, and the antenna 30. FIG.

As shown in FIG. 2, the waveguide block 11 is attached to the printed circuit board 13 on the second conductor pattern 17 side. The waveguide block 11 has an opening functioning as the first waveguide 40 and an opening functioning as the transformer waveguide 51 therein.

As the first waveguide 40, for example, a standard waveguide defined in the standards for waveguides can be used. For example, the first waveguide 40 is a hollow rectangular waveguide (nominal inner diameter: 1.27 mm×2.54 mm) of EIA standard model name WR-10. The impedance of the first waveguide 40 is, for example, 368.2Ω. In FIG. 2, the waveguide direction (the direction in which electromagnetic waves are transmitted) of the first waveguide 40 is the y direction (vertical direction in FIG. 2). In FIG. 2, the first waveguide 40 has a waveguide terminating end at its upper end and a waveguide starting end outside the drawing. In addition, as shown in FIG. 1, the printed circuit board 13 is provided parallel to the xz plane orthogonal to the y direction. That is, the waveguide direction of the first waveguide 40 intersects, more specifically, perpendicular to the surface direction of the printed circuit board 13 .

As shown in FIG. 6, the first waveguide 40 has a wide-walled E-plane formed parallel to the xy-plane. The first waveguide 40 also has an H plane, which is a narrow wall, formed parallel to the yz plane. The H-plane is orthogonal to the E-plane.

The transformer waveguide 51 shown in FIG. 2 is formed so as to communicate with the opening forming the first waveguide 40 at one end in the waveguide direction (upper end in FIG. 2) which is the end of the first waveguide 40 . It is The transformer waveguide 51 functions as the impedance adjuster 50 . The impedance adjuster 50 matches the first waveguide 40 and the second waveguide 60 . The impedance of transformer waveguide 51 is set to an arbitrary value between the impedances of first waveguide 40 and second waveguide 60 .

The transformer waveguide 51 has a length of about λ/4 in the waveguide direction (y direction). The transformer waveguide 51 is a hollow rectangular waveguide. The transformer waveguide 51 is narrower than the first waveguide 40 in the z-direction so as to have a lower impedance than the first waveguide 40 . As shown in FIGS. 5 and 6, the transformer waveguide 51 has an E-plane with the same width as the E-plane of the first waveguide 40 . Also, the transformer waveguide 51 has an H-plane narrower than the H-plane of the first waveguide 40 . That is, the H-plane of the transformer waveguide 51 has a smaller dimension in the z-direction than the H-plane of the first waveguide 40 . Also in the transformer waveguide 51, the E plane is parallel to the xy plane, and the H plane is parallel to the yz plane.

The transformer waveguide 51 having a narrow H-plane may be arranged near the center in the z-direction within the width of the first waveguide 40 in the z-direction, as shown in FIG. However, the transformer waveguide 51 is preferably arranged so that one E-plane is flush with one E-plane of the first waveguide 40, as shown in FIG. The arrangement of the transformer waveguide 51 in FIG. 2 facilitates the processing of the first waveguide 40 and the transformer waveguide 51 .

A waveguide terminal end (upper end in FIG. 2) of the transformer waveguide 51 is connected to a second waveguide 60 formed on the printed circuit board 13 through a slit 55 formed in the second conductor pattern 17 of the printed circuit board 13. It is

As shown in FIG. 1, the second waveguide 60 is configured as a substrate integrated waveguide (SIW). A substrate integrated waveguide is a waveguide formed on a printed circuit board. The substrate integrated waveguide has a plurality of vias 61 and 63 forming post walls. As shown in FIG. 1, the first conductor pattern 15 has a square second waveguide pattern 65 in a plan view to constitute the second waveguide 60 . The vias 61 and 63 are formed in the second waveguide pattern 65 so as to penetrate the dielectric substrate 19 in order to connect the first conductor pattern 15 and the second conductor pattern 17 serving as the ground plane. (See Figure 3). A via is also called a through hole. Here, the term "via" is used as a concept that also includes through holes.

In FIG. 1, the waveguide direction of the second waveguide 60 is the z direction (horizontal direction in FIGS. 1 and 2). In FIG. 1, the slit 55 is the input end of the second waveguide 60, and the front end 65A on the microstrip line 80 side is the second waveguide termination (output end). That is, the second waveguide 60 extends in the z-direction, which is the direction intersecting the E-plane of the first waveguide 40 . The second waveguide 60 can be formed on the same plane as the microstrip line 80 by extending the second waveguide 60 in a direction intersecting the E-plane of the first waveguide 40 .

The vias 61 and 63 forming the post walls include a via 61 formed on the rear side in the waveguide direction and vias 63 formed on both sides in the width direction (x direction) when viewed in the waveguide direction (z direction). . As shown in FIG. 1, the via 61 is provided along the side of the rear end 65D of the second waveguide pattern 65. As shown in FIG. The vias 63 are provided along the left edge 65B and the right edge 65C of the second waveguide pattern 65 .

The second waveguide 60 is formed such that the width L2 in the x direction is 2.54 mm, which is the same as that of the first waveguide 40 and transformer waveguide 51 . Also, since the dielectric base material 19 has a thickness of 0.127 mm, the second waveguide 60 is an SIW with an inner diameter of 0.127 mm×2.54 mm. The impedance of the second waveguide 60 is, for example, 14.4Ω.

As shown in FIG. 4, the aforementioned slit 55 is provided within a range surrounded by a plurality of vias 61 and 63 forming post walls. The slit 55 is formed such that its longitudinal direction coincides with the x direction. Moreover, as shown in FIG. 5, the slit 55 is formed so as to be positioned within the range of the opening of the transformer waveguide 51 .

Here, FIG. 8 shows a modification of the transmission line structure shown in FIGS. In the second waveguide 60 shown in FIG. 8, the via 61 does not constitute the post wall on the pattern rear end 65D side, but the conductive film 101 formed on the side surface of the rear end of the dielectric substrate 19. The post wall is constructed by The circuit of the transmission line structure of FIG. 8 and the circuit of the transmission line structure of FIG. 2 are equivalent. In this case, a slit 55 connecting the transformer waveguide 51 and the second waveguide 60 is formed near the conductor film 101 .

Furthermore, FIG. 9 shows a transmission line structure in which a via 61 is formed at the position of the conductor film 101 shown in FIG. FIG. 9 also shows a circuit structure equivalent to FIGS. The via 61 in FIG. 9 is formed closer to the slit 55 than the via 61 in FIG. Comparing the structure of FIG. 9 with the structure of FIG. 2, the structure of FIG. 2 is easier to manufacture. That is, in FIG. 9, the via 61 and the slit 55 are very close to each other. Since the vias 61 and the slits 55 are portions that require processing of the second conductive pattern 17, processing becomes difficult if the vias 61 and the slits 55 are close to each other.

On the other hand, as shown in FIG. 2, if the via 61 is separated by λg/2 (λg is the wavelength in the substrate integrated waveguide), the structure of the via 61 and the slit 55 is equivalent to that of FIG. Since the distance L1 can be increased, processing becomes easier. The distance between the via 61 and the slit 55 may be (λg/2)×N (N is an integer equal to or greater than 1).

Moreover, as shown in FIG. 8, the slit 55 should be close to the rear end surface (left side surface in FIG. 8) of the transformer waveguide 51 . However, in this case, the slit 55 needs to be positioned in the opening of the transformer waveguide 51 while being positioned around the opening of the transformer waveguide 51, which requires high assembly accuracy. That is, if the slit 55 is positioned outside the opening of the transformer waveguide 51 due to an assembly error between the printed circuit board 13 and the waveguide block 11, the characteristics are significantly degraded. In order to allow a relatively large assembly error, the slit 55 is preferably located near the center of the opening of the transformer waveguide 51 in the width direction, as shown in FIGS.

As shown in FIGS. 1, 3, and 4, in the embodiment, as the impedance adjustment section 50, in addition to the transformer waveguide 51 described above, vias ( impedance adjusting vias) 53 are provided. Vias 53 allow greater adjustment of impedance. The via 53 is provided within a range surrounded by a plurality of vias 61 and 63 forming post walls. In an embodiment, via 53 is provided between slit 55 and second waveguide termination 65A. The vias 53 are formed to penetrate the dielectric substrate 19 in order to connect the first conductor pattern 15 and the second conductor pattern 17 serving as the ground plane.

In the embodiment, vias 53 are provided near slits 55 to facilitate impedance adjustment. The impedance adjustment factor in the via 53 is, for example, the diameter of the via 53 or the distance between the via 53 and the slit 55 . Although the number of vias 53 may be one, the number of vias 53 may be two or more as shown in the drawing, thereby facilitating impedance adjustment. That is, when a plurality of vias 53 are provided, the spacing between the plurality of vias 53 can also be used as an impedance adjustment factor. The direction in which the plurality of vias 53 are arranged is preferably parallel to the longitudinal direction (x direction) of the slits 55 .

As shown in FIG. 1, the first conductor pattern 15 has a pattern forming a transducer 70 formed at the front end 65A of the second waveguide pattern 65. As shown in FIG. The pattern that makes up transducer 70 is tapered. Converter 70 performs mode conversion between second waveguide 60 and microstripline 80 .

The first conductor pattern 15 has a pattern that forms a microstrip line 80 that is continuous with the pattern that forms the transducer 70 . The impedance of the microstop line is, for example, 67Ω. Microstrip line 80 is connected to antenna 30 formed on printed circuit board 13 . Antenna 30 is, for example, a patch antenna and is fed by microstrip line 80 .

Since the second waveguide 60 and the microstrip line 80 are both provided on the printed circuit board 13, the tapered pattern of the converter 70 formed on the printed circuit board 13 ensures wideband performance in the converter 70. Easy.

When mode conversion is performed between a hollow waveguide such as the first waveguide 40 and the microstrip line 80 formed on the printed circuit board 13, since the impedance of the hollow waveguide is large, it is difficult to broaden the band. It's not easy. As a result, in order to widen the band, for example, a separate component such as a back short described in Non-Patent Document 1 is required. On the other hand, in the present embodiment, the first waveguide 40, which is a hollow rectangular waveguide, is converted into the second waveguide 60, which is thin and low-impedance like the microstrip line 80, through the transformer waveguide 51. It is As a result, since the converter 70 only needs to perform mode conversion between the thin second waveguide 60 and the microstrip line 80, it is easy to ensure broadband performance in the converter 70. FIG. Therefore, the tapered pattern formed on the printed circuit board 13 suffices for the converter 70 of the second waveguide-microstrip line 80 .

On the other hand, the transmission line 20 of this embodiment has a first waveguide 40 which is a hollow waveguide and a second waveguide 60 formed on the printed circuit board 13 . Therefore, the impedance adjuster 50 is required to match the first waveguide 40 and the second waveguide 60 . Moreover, the impedance of the first waveguide 40, which is a hollow waveguide, is relatively large (for example, 368.2Ω), whereas the impedance of the second waveguide 60, which is thin because it is formed on the printed circuit board 13, is relatively high. Small (eg, 14.4Ω).

It is preferable that the impedance of the second waveguide 60 is small in relation to the microstrip line 80 . From this point of view, the impedance of the second waveguide 60 is, for example, 1/1.2 or less of the impedance of the first waveguide 40 . When the impedance of the second waveguide 60 becomes 1/1.2 or less of the impedance of the first waveguide 40, the impedance adjuster 50 such as the transformer waveguide 51 is often required. The impedance of the second waveguide 60 may be 1/1.3 or less, 1/2 or less, 1/5 or less, or 1/1.3 or less of the impedance of the first waveguide 40 . /10 or less may be sufficient.

If the impedance of the second waveguide 60 is too small, matching becomes difficult even if the impedance adjuster 50 is provided, so it is preferable that the impedance is not too small. From this point of view, the impedance of the second waveguide 60 is, for example, 1/45 or more of the impedance of the first waveguide 40 . The impedance of the second waveguide 60 may be 1/30 or more, or 1/20 or more, of the impedance of the first waveguide 40 .

As described above, even if the impedance ratio between the first waveguide 40 and the second waveguide 60 is large, according to the present embodiment, the impedance adjuster 50 adjusts the impedance between the first waveguide 40 and the second waveguide 60. Alignment is ensured. Moreover, since the impedance adjustment section 50 has not only the transformer waveguide 51 but also the via 53, it is possible to cope with a large impedance ratio.

As an example of the impedance ratio, the impedance of the second waveguide 60 can be, for example, 1/45 or more and 1/1.3 or less of the impedance of the first waveguide 40 . In this case, in the ±2 GHz band of the frequency band of 76.5 GHz, adjustment to VSWR<1.3 is possible, and wideband performance can be easily ensured.

As another example of the impedance ratio, the impedance of the second waveguide 60 can be, for example, 1/20 or more and 1/1.2 or less of the impedance of the first waveguide 40 . In this case, it is possible to adjust to VSWR<1.2 in the ±2 GHz band of the frequency band of 76.5 GHz, and it is possible to easily ensure wideband performance.

[2.2 Second Embodiment]

FIG. 10 shows an antenna device having a transmission line structure according to the second embodiment. The second embodiment differs from the first embodiment in the size of the second waveguide pattern 65 . In the second embodiment, the second waveguide pattern 65 is formed in such a size that its left end 65B, right end 65C and rear end 65D reach the periphery of the printed circuit board 13 . That is, the distance from the via 63 forming the post wall to the pattern left end 65B is L12 in the first embodiment (FIG. 1), while it is L22 in the second embodiment (FIG. 10), where L12<L22. is. Further, the distance from the via 63 forming the post wall to the pattern right end 65C is L13 in the first embodiment (FIG. 1), while it is L23 in the second embodiment (FIG. 10), where L13<L23. is. Further, the distance from the via 61 constituting the post wall to the pattern rear end 65D is L14 in the first embodiment (FIG. 1), while it is L24 in the second embodiment (FIG. 10), where L14< It is L24.

As in the second embodiment shown in FIG. 10, even if the first conductor pattern 15 is larger than the size required for the second waveguide 60, the same characteristics as in the first embodiment can be obtained.

In the via 63, the lengths L11 and L21 from the center of the via (output end via) 63 closest to the output end (pattern end) 65A of the second waveguide 60 to the pattern end 65A are The second embodiment is the same. L11 and L21 are, for example, 0.3 mm. Here, the lengths L11 and L21 from the center of the output end via 63 to the pattern end 65A are 0.1λg (λg is the wavelength in the front substrate integrated waveguide) or less. By setting it to 0.1λg or less, electromagnetic waves can be prevented from leaking from the inside of the second waveguide 60 to the outside of the second waveguide 60 between the output end via 63 and the pattern end 65A.

In addition, in the second embodiment, in order to prevent electromagnetic waves from entering from the pattern end 65A, corresponding to the fact that L22 and L23 are increased, additional vias 67 are provided along the pattern end 65A. . Vias 67 may be omitted.

In addition, in 2nd Embodiment, it is the same as that of 1st Embodiment about the point which description was abbreviate|omitted.

[2.3 Third Embodiment]

FIG. 11 shows an antenna device having a transmission line structure according to the third embodiment. The third embodiment differs from the first embodiment in that the size of the second waveguide pattern 65 is different and the stub 110 formed in the second waveguide pattern 65 is present.

The second waveguide pattern 65 of the third embodiment is formed larger than the second waveguide pattern 65 of the first embodiment. 11 is longer than L11 in FIG. 1, L32 in FIG. 11 is longer than L12 in FIG. 1, and L3 in FIG. 11 is longer than L13 in FIG. By forming the second waveguide pattern 65 large, the length from the via 63 to the pattern ends 65A, 65B, and 65C of the second waveguide pattern 65 can be increased, and the manufacturing of the second waveguide pattern 65 is facilitated. .

In the third embodiment, unlike the second embodiment, the length L31 from the center of the output end via 63 closest to the second waveguide pattern end 65A to the pattern end 65A among the vias 63 is set to 0.1λg ( λg is 0.65 mm, which is larger than the wavelength in the integrated waveguide on the previous substrate. Therefore, there is a possibility that an electromagnetic wave leaks from the inside of the second waveguide 60 to the outside of the second waveguide 60 between the output end via 63 and the pattern end 65A.

Therefore, in the third embodiment, a structure is adopted to suppress the leakage path from the output end via 63 to the pattern end 65A. This structure is for arranging a virtual via 63A between the output end via 63 and the pattern end 65A instead of providing an actual via 63 between the output end via 63 and the pattern end 65A. This structure has a stub 110 formed in the second waveguide pattern 65 . In the third embodiment, stub 110 is configured as an open stub. The open stub 110 has a line length of λg/4. The open stub 110 has an open tip and a short base. Also, a short circuit occurs at a position separated by λg/2 from the base short circuit position.

Therefore, at the pattern ends (pattern ends 65B and 65C in FIG. 8) of the second waveguide pattern 65, a position λg/2 away from the position where the virtual via 63A is desired to be arranged (between the output end via 63 and the pattern end 65A) Furthermore, by forming the base of the open stub 110, the position where the virtual via 63A is desired to be short-circuited. A short can constitute a post wall similar to via 63 . In addition, although the stub 110 is formed in a curved shape in FIG. 11, it may be formed in a straight shape. When the stub is formed in a curved shape, it is possible to suppress an increase in the size of the printed circuit board 13 . Also, a short stub may be employed as the stub 110 .

[2.4 Simulation results]

12 and 13 show simulation results of reflection characteristics of the transmission line structure of the first embodiment. FIG. 12 shows a polar chart of reflection characteristics, and FIG. 13 shows VSWR (voltage standing wave ratio). In the simulation, the diameter of the vias 61 and 63 was set to 0.2 mm, and the spacing (center spacing) between the vias 61 and 63 was set to 0.7 mm. Also, L11, L12, L13, and L14 shown in FIG. 1 were each set to 0.3 mm so as to be about 0.1λg.

As shown in FIG. 13, the range in which the VSWR is 1.2 or less is the range from 73.48 GHz to 82.28 GHz (range of 8.8 GHz), and it can be seen that the wideband property is ensured.

14 to 16 show simulation results of reflection characteristics and transmission characteristics of the transmission line structure of the third embodiment. 14 to 16, FIGS. 14A, 15A, and 16A show simulation results when the stub 110 is omitted from the third embodiment, and FIGS. 14B, 15B, and 16B show simulation results of the third embodiment. there is In the simulation, the diameter of vias 61 and 63 was set to 0.3 mm, and the spacing between vias 61 and 63 was set to 0.8 mm. Also, L31, L32, and L33 shown in FIG. 11 are each set to 0.65 mm. 0.65 mm is greater than 0.1 λg.

Polar charts of reflection characteristics (FIGS. 14A and 14B), VSWR of reflection characteristics (FIGS. 15A and 15B), and transmission characteristics (FIGS. 16A and 16B) when the stub 110 is omitted (FIGS. 14A, 15A and 16A) 14B, 15B, and 16B, the characteristics are improved.

[3. Note]

It should be noted that the embodiments disclosed this time should be considered as examples in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above-described meaning, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.

Reference Signs List 10: Antenna Device 11: Waveguide Block 13: Printed Circuit Board 15: First Conductor Pattern 17: Second Conductor Pattern 19: Dielectric Substrate 20: Transmission Line 30: Antenna 40: First Waveguide 50: Impedance Adjustment Portion 51: transformer waveguide 53: via 55: slit 60: second waveguide 61: via 63: via 63A: virtual via 65: second waveguide pattern 65A: front end 65B: left end 65C: right end 65D: rear end 67: Via 70 : Transducer 80 : Microstrip line 101 : Conductive film 110 : Open stub

Claims (10)

a first waveguide;
an impedance adjustment section including a transformer waveguide provided on one end side of the first waveguide in the waveguide direction and having an H-plane narrower than the H-plane of the first waveguide;
a second waveguide connected to the transformer waveguide via a slit, having a lower impedance than the first waveguide, and extending in a direction intersecting the E-plane of the first waveguide;
with
The second waveguide is a substrate integrated waveguide in which post walls are formed by a plurality of vias connecting the first conductor pattern and the second conductor pattern serving as a ground plane,
A transmission line structure in which the impedance adjustment section includes one or a plurality of impedance adjustment vias provided within a range surrounded by the plurality of vias forming the post wall in the substrate integrated waveguide. a microstrip line formed on a printed circuit board;
a transition between the second waveguide and the microstripline formed on the printed circuit board;
further comprising
The transmission line structure according to claim 1, wherein the second waveguide is formed on the printed circuit board. 3. The transmission line structure according to claim 2, further comprising an antenna formed on said printed circuit board and fed by said microstrip line. a first waveguide;
an impedance adjustment section including a transformer waveguide provided on one end side of the first waveguide in the waveguide direction and having an H-plane narrower than the H-plane of the first waveguide;
a second waveguide connected to the transformer waveguide via a slit, having a lower impedance than the first waveguide, and extending in a direction intersecting the E-plane of the first waveguide;
with
The second waveguide is a substrate integrated waveguide in which post walls are formed by a plurality of vias connecting the first conductor pattern and the second conductor pattern serving as a ground plane,
the first conductor pattern has a pattern end that serves as an output end of the substrate integrated waveguide;
The length from the center of the output end via closest to the pattern end among the plurality of vias constituting the post wall to the pattern end is 0.1λg (λg is the wavelength in the substrate integrated waveguide) or less. A transmission line structure. a first waveguide;
an impedance adjustment section including a transformer waveguide provided on one end side of the first waveguide in the waveguide direction and having an H-plane narrower than the H-plane of the first waveguide;
a second waveguide connected to the transformer waveguide via a slit, having a lower impedance than the first waveguide, and extending in a direction intersecting the E-plane of the first waveguide;
with
The second waveguide is a substrate integrated waveguide in which post walls are formed by a plurality of vias connecting the first conductor pattern and the second conductor pattern serving as a ground plane,
The first conductor pattern is
a pattern end serving as an output end of the substrate integrated waveguide;
a stub for short-circuiting between the output end via closest to the pattern end among the plurality of vias constituting the post wall and the pattern end;
A transmission line structure having 6. The transmission line structure according to claim 5, wherein the stub is an open stub formed at a position for short-circuiting between the output end via and the pattern end. 7. The transmission line structure according to claim 5, wherein a length from the center of said output end via to said pattern edge is greater than 0.1[lambda]g ([lambda]g is the wavelength in said substrate integrated waveguide). a first waveguide;
an impedance adjustment section including a transformer waveguide provided on one end side of the first waveguide in the waveguide direction and having an H-plane narrower than the H-plane of the first waveguide;
a second waveguide connected to the transformer waveguide via a slit, having a lower impedance than the first waveguide, and extending in a direction intersecting the E-plane of the first waveguide;
with
The transmission line structure, wherein the impedance of the second waveguide is 1/45 or more of the impedance of the first waveguide and 1/1.2 or less of the impedance of the first waveguide. 9. The transmission line structure according to claim 8, wherein said impedance of said second waveguide is 1/20 or more of said impedance of said first waveguide. 10. The transmission line structure according to claim 8, wherein the impedance of the second waveguide is 1/1.3 or less of the impedance of the first waveguide.

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