Waveguide converter

Abstract

To provide a waveguide converter that realizes broadband frequency characteristics while suppressing a height of a waveguide.SOLUTION: In a substrate 20, a plurality of pairs of ground vias 52 disposed to face each other with a slit 27 interposed therebetween in a plan view include at least one pair of first ground vias 54 located in a first distance range Lr and at least one pair of second ground vias 56 located in a second distance range Ls away from the first distance range in a direction in which the slit extends from a center of a second opening part 25 in the plan view. The minimum distance Wr between hole walls of the at least one pair of first ground vias is larger than the minimum distance Ws between the hole walls of the at least one pair of second ground vias. A signal in a first frequency band is transmitted through a transmission line 40 in a first resonance mode, and a signal in a second frequency band different from the first frequency band is transmitted through the transmission line in a second resonance mode different from the first resonance mode.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a waveguide converter. [Background technology]

[0002] Patent Document 1 discloses a waveguide converter including a waveguide, a patch conductor, a ground conductor, and a port portion. Patent Document 2 discloses that the conductor patch included in the waveguide converter has protrusions on the short sides near both ends of the long side. Patent Document 3 discloses that the short-circuiting metal layer has cutouts for arranging strip lines, and the short-circuiting metal layer and the strip lines are arranged at a fixed interval on a dielectric substrate. [Prior art document] [Patent documents] [Patent Document 1] JP 2011-055377 A [Patent Document 2] JP 2013-172251 A [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-244212 Summary of the Invention [Problem to be solved by the invention]

[0003] In the above-described waveguide converter, it is desirable to realize wideband frequency characteristics while suppressing the height of the waveguide. [Means for solving the problem]

[0004] A waveguide converter according to one aspect of the present invention may include a substrate and a waveguide having a cavity, the waveguide being disposed on a first surface side of the substrate. The substrate may include a dielectric layer. The substrate may include a first ground conductor layer disposed on the waveguide side of the dielectric layer, the first ground conductor layer having a second opening facing a first opening at one end of the cavity of the waveguide and a slit extending from the second opening along the first surface. The substrate may include a transmission line disposed in the slit and extending along the first surface and the slit without contacting the first ground conductor layer. The substrate may include a conductor patch disposed in the second opening without contacting the first ground conductor layer. The substrate may include a connection line disposed along the first surface within the second opening and the slit, connecting the transmission line and the conductor patch. The substrate may include a second ground conductor layer disposed on the opposite side of the dielectric layer from the first ground conductor layer. The substrate may have a plurality of ground vias arranged along edges of the second opening and the slit in a plan view, electrically connecting the first ground conductor layer and the second ground conductor layer. The plurality of ground vias may include a plurality of pairs of ground vias arranged opposite each other across the slit in a plan view. The plurality of pairs of ground vias may include at least one pair of first ground vias located within a first distance range in a direction in which the slit extends from the center of the second opening in a plan view, and at least one pair of second ground vias located within a second distance range that is farther from the center of the second opening than the first distance range in a plan view. A minimum distance between hole walls of the at least one pair of first ground vias may be wider than a minimum distance between hole walls of the at least one pair of second ground vias. A signal in a first frequency band may be transmitted through the transmission line in a first resonant mode, and a signal in a second frequency band different from the first frequency band may be transmitted through the transmission line in a second resonant mode different from the first resonant mode.

[0005] In the waveguide converter, the first distance range may be a distance range extending from the center of the second opening in a direction in which the slit extends to a distance longer than a distance corresponding to at least 0.55 wavelengths of a signal transmitted through the transmission line in a plan view, and a minimum distance between hole walls of the at least one pair of first ground vias may be a distance corresponding to a wavelength between 0.5 and 0.6 wavelengths of the signal.

[0006] In any of the waveguide converters, the first distance range may be a distance range that is at least longer than a distance corresponding to 0.65 wavelengths of the signal in a direction in which the slit extends from the center of the second opening in a planar view.

[0007] In any of the waveguide converters, the characteristic impedance of the connection line may be different from the characteristic impedance of the transmission line.

[0008] In any of the waveguide converters, the characteristic impedance of the connection line may be a value between the characteristic impedance of the transmission line and the impedance of the conductor patch.

[0009] In any of the waveguide converters, the width of the connection line may be different from the width of the transmission line.

[0010] In any of the waveguide converters, the width of the connection line may be narrower than the width of the transmission line.

[0011] In any of the waveguide converters, the substrate may further include a pair of parasitic elements arranged in the second opening opposite each other with the conductor patch therebetween in a direction intersecting the direction in which the transmission line extends.

[0012] In any of the waveguide converters, the conductor patch may have a sector shape with an intermediate angle between 30 degrees and 160 degrees in a plan view.

[0013] In any of the waveguide converters, the dielectric layer may have a relative permittivity of between 2 and 4.

[0014] In any of the waveguide converters, the thickness of the dielectric layer may be between 0.025 mm and 0.5 mm.

[0015] In any of the waveguide converters, the first distance range may be a distance range up to a distance equivalent to two wavelengths of a signal transmitted through the transmission line in a direction in which the slit extends from the center of the second opening.

[0016] In any of the waveguide converters, the substrate may further include at least one third conductor layer and another dielectric layer that are alternately stacked and disposed on the opposite side of the second ground conductor layer from the dielectric layer.

[0017] The above summary of the invention does not list all of the features of the present invention, and subcombinations of these features may also be inventions. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing an example of an external perspective view of a waveguide converter according to a first embodiment. [Figure 2] 1 is a plan view of a substrate included in a waveguide converter according to a first embodiment, viewed from the first ground conductor layer side. [Figure 3] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 4] 5A and 5B are diagrams illustrating simulation results of the amount of transmission and the amount of reflection of the waveguide converter according to the first embodiment. [Figure 5] FIG. 10 is a plan view of a substrate included in a waveguide converter according to a comparative example. [Figure 6] 10A and 10B are diagrams illustrating simulation results of the amount of transmission and the amount of reflection of a waveguide converter according to a comparative example. [Figure 7] FIG. 5 is a diagram showing the electric field distribution on the substrate at the frequency f0 in FIG. [Figure 8]FIG. 5 is a diagram showing the electric field distribution on the substrate at a frequency of 1.05f0 in FIG. [Figure 9] FIG. 10 is a graph showing the dependence of the bandwidth of a return loss of 15 dB on the minimum distance Wr and the first distance range Lr. [Figure 10] FIG. 10 is a graph showing the dependence of the bandwidth of a return loss of 10 dB on the minimum distance Wr and the first distance range Lr. [Figure 11] FIG. 10 is a plan view of a substrate included in a waveguide converter according to a second embodiment, viewed from the first ground conductor layer side. [Figure 12] FIG. 10 is a plan view of a substrate included in a waveguide converter according to a second embodiment, viewed from the first ground conductor layer side. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0020] In devices with high-frequency transmitting / receiving circuits and antennas, such as those used in automotive radar or millimeter-wave wireless communications, the insertion of a waveguide at the connection between the transmitting / receiving circuit and the antenna can reduce wiring loss and reduce the size of the device. Waveguide converters, which convert power transmitted by a waveguide into power transmitted by a transmission line on a circuit board, are often used as such connections.

[0021] Regarding such waveguide converters, for example, Patent Document 1 discloses a basic structure in which a waveguide is connected to the signal line side of a microstrip line on a substrate. Patent Document 2 also discloses improving frequency characteristics by adding a protrusion to a patch section. Furthermore, Patent Document 3 discloses a structure that achieves a broadband by connecting to a waveguide from the side of a ground conductor that constitutes a microstrip line on a substrate.

[0022] The waveguide converter described in Patent Document 1 has a simple configuration and a low profile, but because it has only one resonance point, its frequency band is narrow in principle, making it difficult to achieve a wideband frequency characteristic of 5% or more, as required for recent millimeter-wave radars.

[0023] The waveguide converter described in Patent Document 2 improves frequency characteristics by adding protrusions to both sides of the conductor patch in the structure described in Patent Document 1. However, the improvement effect is limited, and high-precision patterning is required to add fine protrusions to the conductor patch, resulting in high costs.

[0024] The waveguide converter described in Patent Document 3 can achieve wideband frequency characteristics by adding a short-circuit waveguide section with a length of one-quarter of the wavelength. However, since the height of the short-circuit waveguide section is approximately 1 to 2 mm, it is difficult to reduce the height. In addition, there is a large variation in the processing accuracy of the short-circuit waveguide section, making it unsuitable for mass production. Furthermore, since the waveguide is installed on the side opposite the signal line side of the transmission line, if a multilayer substrate is used, it is necessary to use expensive substrate materials with low dielectric constants and low dielectric loss tangents for all layers, resulting in a high-cost configuration.

[0025] Therefore, the waveguide converter according to this embodiment realizes wideband frequency characteristics while suppressing the height of the waveguide.

[0026] Fig. 1 shows an example of an external perspective view of a waveguide converter 10 according to the first embodiment. Fig. 2 is a plan view of a substrate 20 included in the waveguide converter 10, viewed from the first ground conductor layer 24 side. Fig. 3 is a cross-sectional view taken along line AA in Fig. 1. In Fig. 1, the direction along the long side of the conductor patch 42 is the X-axis, the direction along the short side of the conductor patch 42 is the Y-axis, and the direction in which the cavity 32 of the waveguide 30 extends is the Z-axis. This is the same for the other figures.

[0027] The waveguide converter 10 includes a substrate 20 and a waveguide 30. The waveguide 30 is disposed on the first surface 20a side of the substrate 20. The waveguide 30 has a rectangular cylindrical cavity 32 surrounded by a conductive wall. The waveguide 30 has a first opening 33 at one end of the cavity 32. The first opening 33 is formed by a cross section of the cavity 32 in a direction perpendicular to the signal transmission direction. An antenna for emitting and receiving high-frequency signals such as microwaves or millimeter waves may be connected to the other end of the cavity 32.

[0028] The waveguide 30 may be made of an aluminum alloy. Alternatively, the waveguide 30 may be made of other waveguide conductors, such as gold-plated brass or resin plated with a conductor. The cross-sectional shape of the cavity 32 of the waveguide 30, i.e., the shape of the first opening 33, may be a square, rectangle, or other rectangular shape. The first opening 33 may have dimensions of, for example, 3.099 mm long and 1.549 mm short, which conform to the WG-12 standard for the 79 GHz band.

[0029] The substrate 20 has a dielectric layer 22, a first ground conductor layer 24, and a second ground conductor layer 26. The first ground conductor layer 24 is disposed on the waveguide 30 side of the dielectric layer 22, and has a second opening 25 facing the first opening 33 of the waveguide 30, and a slit 27 extending from the second opening 25 along the first surface 20a. The second opening 25 has a shape that follows the first opening 33 of the waveguide 30, and the size of the second opening 25 may be smaller than the size of the first opening 33. The center of the first opening 33 of the waveguide 30 and the center of the second opening 25 coincide with each other in a plan view.

[0030] The second ground conductor layer 26 is disposed on the opposite side of the dielectric layer 22 from the first ground conductor layer 24. The dielectric layer 22 may have a relative permittivity between 2 and 4, e.g., 3.1. The dielectric layer 22 may have a thickness of, e.g., 0.025 mm or more and 0.5 mm or less. The substrate 20 may be an organic or inorganic substrate having two or more copper conductor layers, each having a thickness of 1 μm or more, including the first ground conductor layer 24 and the second ground conductor layer 26. The substrate 20 may further include at least one third conductor layer and another dielectric layer, which are alternately stacked, disposed on the opposite side of the dielectric layer 22 from the second ground conductor layer 26. That is, the substrate 20 may be configured with multiple layers, in which conductor layers and other dielectric layers are alternately arranged, in addition to the first ground conductor layer 24 and the second ground conductor layer 26.

[0031] The substrate 20 further has a transmission line 40, a conductor patch 42, and a connection line 44. The transmission line 40 is disposed within the slit 27 and extends along the first surface 20a and the slit 27 without making contact with the first ground conductor layer 24. The conductor patch 42 is disposed within the second opening 25 without making contact with the first ground conductor layer 24. The connection line 44 is disposed within the second opening 25 and the slit 27 along the first surface 20a, and connects the transmission line 40 and the conductor patch 42.

[0032] The shape of the conductor patch 42 is a rectangle or square whose short sides are approximately half the wavelength of the signal transmitted through the transmission line 40, in accordance with the TE01 mode of the waveguide 30. The characteristic impedance of the connection line 44 may be different from the characteristic impedance of the transmission line 40. The characteristic impedance of the connection line 44 may be a value between the characteristic impedance of the transmission line 40 and the impedance of the conductor patch 42. The width of the connection line 44 may be different from the width of the transmission line 40. The width of the connection line 44 may be narrower than the width of the transmission line 40.

[0033] Note that the connection line 44 may not be used depending on the characteristic impedance of the transmission line 40. In other words, the characteristic impedance of the connection line 44 may be the same as the characteristic impedance of the transmission line 40. In other words, the width of the connection line 44 may be the same as the width of the transmission line 40.

[0034] The first ground conductor layer 24 may be formed by cutting out a ground conductor plate along the transmission line 40, the conductor patch 42, and the connecting line 44. The second ground conductor layer 26 may be formed from a conductor that covers the entire surface of the substrate 20 or has a width that sufficiently covers the transmission line 40, the conductor patch 42, and the connecting line 44 in a plan view.

[0035] The waveguide 30 has a notch 34 communicating with the cavity 32 to prevent the transmission line 40 and the connection line 44 from contacting the waveguide 30 at the contact surface between the waveguide 30 and the substrate 20 and electrically coupling the transmission line 40 and the connection line 44 to the waveguide 30. The height of the notch 34 may be 0.5 mm or more, and the width of the notch 34 may be 0.9 mm or more. The notch 34 may be formed by cutting out a part of the conductor wall of the waveguide 30.

[0036] The substrate 20 further has a plurality of ground vias 50. The plurality of ground vias 50 are made of a conductor and are arranged along the edges of the second opening 25 and the slit 27 in plan view, electrically connecting the first ground conductor layer 24 and the second ground conductor layer 26. The plurality of ground vias 50 are arranged so as to surround the same potential portion consisting of the transmission line 40, the conductor patch 42, and the connection line 44.

[0037] The plurality of ground vias 50 includes a plurality of pairs of ground vias 52 arranged opposite each other with the slit 27 interposed therebetween in a plan view. The plurality of pairs of ground vias 52 includes a plurality of pairs of first ground vias 54 located in a first distance range Lr in a direction in which the slit 27 extends from the center of the second opening 42 in a plan view, and a plurality of pairs of second ground vias 56 located in a second distance range Ls that is farther from the first distance range Lr. The plurality of pairs of ground vias 52 may include at least one pair of first ground vias 54 and at least one pair of second ground vias 56.

[0038] The minimum distance Wr between the hole walls of the pair of first ground vias 54 is wider than the minimum distance Ws between the hole walls of the pair of second ground vias 56. With this configuration, signals in a first frequency band are transmitted through the transmission line 40 in a first resonance mode such as the TE01 mode, and signals in a second frequency band different from the first frequency band are transmitted through the transmission line 40 in a second resonance mode such as a higher-order mode different from the first resonance mode.

[0039] The first distance range Lr may be a distance range that is at least longer than a distance corresponding to 0.55 wavelengths of the wavelength of a signal transmitted through the transmission line 40 in a direction from the center of the second opening 25 to the extension of the slit 27 in a planar view. The first distance range Lr may be a distance range that is at least longer than a distance corresponding to 0.65 wavelengths of the signal in a planar view in a direction from the center of the second opening 25 to the extension of the slit 27. The first distance range Lr may be a distance range that is at least longer than a distance corresponding to two wavelengths of the wavelength of a signal transmitted through the transmission line 40 in a direction from the center of the second opening 25 to the extension of the slit 27. Setting the first distance range Lr to a distance corresponding to two wavelengths enables space saving on the board area.

[0040] The minimum distance Wr between the hole walls of a pair of first ground vias 54 may be a distance corresponding to a wavelength between 0.5 and 0.6 of the wavelength of the signal.

[0041] By arranging the pair of ground vias 52 and the pair of second ground vias 56 in the above-described manner, in addition to the first TM01 mode, which is the resonant mode in the substrate 20 excited by the conductor patch 42, a second higher-order mode is formed in a frequency band different from the first TM01 mode, thereby reducing reflection loss and insertion loss.

[0042] The minimum distance Wr between the hole walls of the pair of first ground vias 54 may be, for example, 0.57 wavelengths of the signal wavelength on the substrate 20 (for example, 1.23 mm in the 79 GHz band). In addition, by maintaining the first distance range Lr of the pair of first ground vias 54 arranged at the minimum distance Wr up to a distance of 0.8 wavelengths of the signal wavelength (for example, 1.73 mm in the 79 GHz band) from the center of the first opening 33 of the waveguide 30 in contact with the substrate 20, i.e., the center of the second opening 25, in the direction of the short side of the second opening 25 (the direction in which the slit 27 extends), the waveguide converter 10 can be controlled to configure a resonator that forms a higher-order mode.

[0043] FIG. 4 shows an example of frequency characteristics obtained by simulating the transmission and reflection amounts of the waveguide converter 10 according to the first embodiment. FIG. 5 is a plan view of a substrate 200 included in a waveguide converter according to a comparative example. In the comparative example, the minimum distance between the hole walls of a pair of ground vias 58 arranged opposite each other with a slit 27 in between does not satisfy the conditions of the waveguide converter 10 according to the first embodiment. For example, the minimum distance between the hole walls of a pair of ground vias 58 arranged opposite each other with a slit 27 in between are all the same. FIG. 6 shows an example of frequency characteristics obtained by simulating the transmission and reflection amounts of the waveguide converter 100 according to the comparative example.

[0044] 6, the waveguide converter 100 according to the comparative example can ensure a bandwidth of 15 dB of reflection of about 2%, whereas the waveguide converter 10 according to the first embodiment can ensure a bandwidth of 15 dB of reflection of 8% or more. In other words, the waveguide converter 10 can achieve frequency characteristics with a wider bandwidth than the waveguide converter 100.

[0045] Fig. 7 shows the electric field distribution on the substrate 20 at the frequency f0 in Fig. 4. Fig. 8 shows the electric field distribution on the substrate 20 at the frequency 1.05f0 in Fig. 4. The waveguide converter 10 according to the first embodiment forms higher-order modes on the substrate 20, and the resonance points of the higher-order modes contribute to widening the frequency band.

[0046] Fig. 9 shows a graph illustrating the dependence of the bandwidth at which the return loss is 15 dB on the minimum distance Wr and the first distance range Lr. Fig. 10 shows a graph illustrating the dependence of the bandwidth at which the return loss is 10 dB on the minimum distance Wr and the first distance range Lr. As can be seen from the results shown in Figs. 9 and 10, the minimum distance Wr between the walls of the ground vias 54 results in a trade-off between the required return loss and bandwidth, so it is possible to select an optimum value depending on the application used.

[0047] For example, to ensure a reflection amount of 2% or more of the 15 dB bandwidth, the minimum distance Wr between the hole walls of a pair of first ground vias 54 is preferably a distance corresponding to a wavelength between 0.5 and 0.6 of the wavelength of the signal transmitted through the transmission line 40. Furthermore, the first distance range Lr is preferably a distance range up to a distance longer than a distance corresponding to at least 0.55 wavelengths or at least 0.65 wavelengths.

[0048] Similarly, for example, to ensure 8% or more of the 10 dB bandwidth of the reflection amount, the minimum distance Wr between the hole walls of a pair of first ground vias 54 is preferably a distance corresponding to a wavelength between 0.5 and 0.6 of the wavelength of the signal transmitted through the transmission line 40. Furthermore, the first distance range Lr is preferably a distance range up to a distance longer than a distance corresponding to at least 0.55 wavelengths, or at least 0.65 wavelengths.

[0049] 11 is a plan view of a substrate 20A included in a waveguide converter according to the second embodiment. The substrate 20A differs from the substrate 20 of the first embodiment in that the substrate 20A includes a pair of parasitic elements 46 arranged opposite each other with the conductor patch 42 interposed therebetween in a direction (X-axis direction) intersecting the direction in which the transmission line 40 extends, within the second opening 25. The addition of a sub-resonance point by the pair of parasitic elements 46 enables the frequency band to be further widened.

[0050] 12 is a plan view of a substrate 20B included in a waveguide converter according to the third embodiment. The substrate 20B differs from the substrate 20 of the first embodiment in that it includes a sector-shaped conductor patch 48 with a mid-angle between 30 degrees and 160 degrees in plan view. By replacing the conductor patch with a sector-shaped probe, it is possible to further widen the frequency band.

[0051] According to the waveguide converters of the respective embodiments, wideband frequency characteristics can be achieved with low loss and low cost even in a configuration in which a waveguide is connected to the signal line side of a transmission line, which does not require the addition of a short-circuiting waveguide, which is expensive and hinders a reduction in height.

[0052] As shown in FIG. 6, the structure according to the comparative example only has a TM01 mode resonance point, so the frequency bandwidth at which the return loss is 15 dB is approximately 2%. On the other hand, when the structure according to each embodiment is applied, two resonance points can be created at close frequencies, as shown in FIG. 4, improving the bandwidth at which the return loss is 15 dB by up to approximately 8%. This additional resonance point is generated by generating a higher-order mode in the resonant portion of the substrate 20 formed by the ground vias 50 and 52 (54 and 56) as shown in FIG. 8, in addition to the TM01 mode in the substrate, which is also present in the structure according to the comparative example, as shown in FIG. 7. This creates two resonance points within the frequency band, achieving wideband and low-loss characteristics. By adopting the structure according to each embodiment, it is possible to perform low-loss power conversion between the waveguide and the transmission line over a wide bandwidth, even in a configuration in which a waveguide is connected to the signal line side.

[0053] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0054] It should be noted that the execution order of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order. [Explanation of symbols]

[0055] 10 Waveguide converter 20, 20A, 20B board 22 Dielectric layer 24 First Ground Conductor Layer 25 Second opening 26 Second ground conductor layer 27 Slit 30 Waveguide 32 Cavity 33 First Opening 34 Notch 40 Transmission Line 42,48 Conductor patch 44 Connecting Line 46 Parasitic element 50, 52, 54, 56, 58 Ground vias 100 Waveguide converter 200 boards Wr Minimum Distance Lr 1st distance range

Claims

1. A substrate; a waveguide having a cavity, the waveguide being disposed on the first surface side of the substrate; Equipped with The substrate is a dielectric layer; a first ground conductor layer disposed on the waveguide side of the dielectric layer, the first ground conductor layer having a second opening facing a first opening at one end of the cavity of the waveguide, and a slit extending from the second opening along the first surface; a transmission line disposed within the slit and extending along the first surface and the slit without contacting the first ground conductor layer; a conductor patch disposed within the second opening without contacting the first ground conductor layer; a connection line disposed within the second opening and the slit along the first surface, the connection line connecting the transmission line and the conductor patch; a second ground conductor layer disposed on the dielectric layer opposite the first ground conductor layer; a plurality of ground vias arranged along edges of the second opening and the slit in a plan view, the ground vias electrically connecting the first ground conductor layer and the second ground conductor layer; and the plurality of ground vias include a plurality of pairs of ground vias arranged opposite each other with the slit therebetween in a plan view, the plurality of pairs of ground vias include, in a plan view, at least one pair of first ground vias located within a first distance range in a direction in which the slit extends from the center of the second opening, and at least one pair of second ground vias located within a second distance range that is farther from the center of the second opening than the first distance range; a minimum distance between hole walls of the at least one pair of first ground vias is greater than a minimum distance between hole walls of the at least one pair of second ground vias; A waveguide converter, wherein a signal in a first frequency band is transmitted through the transmission line in a first resonant mode, and a signal in a second frequency band different from the first frequency band is transmitted through the transmission line in a second resonant mode different from the first resonant mode.

2. the first distance range is a distance range that is longer than a distance corresponding to at least 0.55 wavelength of a signal transmitted through the transmission line in a direction in which the slit extends from a center of the second opening in a plan view, 2. The waveguide converter according to claim 1, wherein the minimum distance between the hole walls of the at least one pair of first ground vias is a distance corresponding to a wavelength between 0.5 and 0.6 of the wavelength of the signal.

3. 3. The waveguide converter according to claim 2, wherein the first distance range is a distance range that is at least longer than a distance corresponding to 0.65 wavelengths of the signal in a direction in which the slit extends from a center of the second opening in a planar view.

4. The waveguide converter according to claim 1 , wherein the characteristic impedance of the connection line is different from the characteristic impedance of the transmission line.

5. 5. The waveguide converter according to claim 4, wherein the characteristic impedance of the connection line is a value between the characteristic impedance of the transmission line and the impedance of the conductor patch.

6. The waveguide transition of claim 1 , wherein the width of the connection line is different from the width of the transmission line.

7. The waveguide converter according to claim 6 , wherein the width of the connection line is narrower than the width of the transmission line.

8. 2. The waveguide converter according to claim 1, wherein the substrate further comprises a pair of parasitic elements arranged in the second opening opposite each other with the conductor patch therebetween in a direction intersecting a direction in which the transmission line extends.

9. The waveguide converter according to claim 1 , wherein the conductor patch has a sector shape with an intermediate angle between 30 degrees and 160 degrees in a plan view.

10. 2. The waveguide transition of claim 1, wherein the dielectric layer has a relative permittivity of between 2 and 4.

11. 2. The waveguide transition of claim 1, wherein the thickness of the dielectric layer is between 0.025 mm and 0.5 mm.

12. 4. The waveguide converter according to claim 2, wherein the first distance range is a distance range up to a distance corresponding to two wavelengths of a signal transmitted through the transmission line in a direction in which the slit extends from a center of the second opening.

13. 2. The waveguide converter of claim 1, wherein the substrate further comprises at least one third conductor layer and another dielectric layer that are alternately stacked and disposed on the opposite side of the second ground conductor layer from the dielectric layer.

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