Mode conversion structure

Abstract

A mode conversion structure according to one embodiment of the present disclosure is provided with: a first dielectric substrate having a first thickness and having a microstrip line comprising a line conductor and a first ground conductor facing the line conductor; a second dielectric substrate having a pillar wall waveguide including a first conductor layer connected to the line conductor on the same plane and a second conductor layer facing the first conductor layer, and having a second thickness thicker than the first thickness; and a first via electrically connecting the first ground conductor and the second conductor layer.

Description

Technical Field

[0001] The present disclosure relates to a mode switching structure. Background Art

[0002] In many cases, microstrip lines are used as a means of transmitting high-frequency signals on dielectric substrates. However, in the millimeter wave and terahertz wave bands, the transmission loss caused by conductor loss increases due to the skin effect and the influence of interface unevenness, which are phenomena inherent to high frequencies.

[0003] The conductor loss can be reduced by increasing the thickness of the dielectric (substrate) constituting the microstrip line. However, in this case, the radiation loss in which energy is radiated as electromagnetic waves increases, making it difficult to reduce the transmission loss.

[0004] On the other hand, as one of the means to reduce transmission loss, there is a pillar-wall waveguide structure, that is, a dielectric is sandwiched between a pair of conductor layers, and the conductor layers are electrically connected to each other by a group of via holes arranged at intervals of λ / 2 (λ: wavelength of electromagnetic waves) in the signal transmission direction (propagation direction of electromagnetic waves), and the main conductor layer is used as the wide wall of the waveguide, and the group of via holes is used as the narrow wall of the waveguide. Since the pillar-wall waveguide is surrounded by conductors, the radiation loss does not increase even if the substrate thickness is increased. Therefore, the dielectric can be made thicker, and the conductor loss and radiation loss can be reduced at the same time.

[0005] If we consider the installation of integrated circuits (ICs) that generate high-frequency signals, it is known that ICs are mostly installed on microstrip lines via solder balls, and it is difficult to directly supply power to the pillar wall waveguide. Therefore, when the pillar wall waveguide is used as a transmission path, a propagation (transmission) mode conversion structure (hereinafter referred to as a mode conversion structure) connecting the microstrip line and the pillar wall waveguide is formed. In addition, the term "mode conversion structure" can also be replaced by the term "mode conversion device" and the like.

[0006] As a prior art of mode conversion structure, for example, Patent Document 1 discloses a mode conversion structure in which a line conductor of a microstrip line and one wide wall of a pillar-wall waveguide are located on the same plane, and a ground conductor (hereinafter referred to as GND) of the microstrip line and another wide wall of the pillar-wall waveguide are located on the same plane (connecting a microstrip line and a pillar-wall waveguide of the same thickness).

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2004-153368 Summary of the invention

[0010] However, in the conventional technology described in Patent Document 1, the thickness of the microstrip line is the same as the thickness of the pillar-walled waveguide, and therefore it is difficult to connect the microstrip line and the pillar-walled waveguide having different thicknesses.

[0011] In the prior art described in Patent Document 1, when a thin microstrip line and a thin column-walled waveguide are connected, the radiation loss decreases and the conductor loss increases, and when a thick microstrip line and a thick column-walled waveguide are connected, the conductor loss decreases and the radiation loss increases, making it difficult to reduce the radiation loss of the microstrip line and the conductor loss of the column-walled waveguide.

[0012] Non-limiting embodiments of the present disclosure contribute to providing a mode conversion structure capable of connecting a microstrip line and a cylindrical waveguide having different thicknesses while suppressing transmission loss.

[0013] A mode conversion structure according to an embodiment of the present disclosure includes: a first dielectric substrate having a microstrip line composed of a line conductor and a first ground conductor opposite to the line conductor and having a first thickness; a second dielectric substrate having a pillar-walled waveguide having a second thickness thicker than the first thickness, the pillar-walled waveguide including a first conductor layer connected to the line conductor on the same plane and a second conductor layer opposite to the first conductor layer; and a first through hole electrically connecting the first ground conductor and the second conductor layer.

[0014] According to one embodiment of the present disclosure, a microstrip line and a cylindrical waveguide having different thicknesses can be connected while suppressing transmission loss.

[0015] More advantages and effects of an embodiment of the present disclosure will be explained through the description and drawings. These advantages and / or effects are provided by several embodiments, and the features described in the description and drawings, but not necessarily all of them need to be provided in order to obtain one or more of the same features. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a perspective view showing the mode conversion structure according to the first embodiment of the present disclosure.

[0017] Figure 2 It is a side cross-sectional view showing the mode conversion structure according to the first embodiment of the present disclosure.

[0018] Figure 3 It is a perspective view showing a mode conversion structure of a comparative example (example of the prior art).

[0019] Figure 4 is a side cross-sectional view showing a mode conversion structure of a comparative example.

[0020] Figure 5It is a diagram showing the results of simulation of radiation power of the mode conversion structure according to the first embodiment of the present disclosure and the mode conversion structure according to the comparative example.

[0021] Figure 6 It is a perspective view showing a mode conversion structure according to Embodiment 2 of the present disclosure.

[0022] Figure 7 It is a side cross-sectional view showing a mode conversion structure according to Embodiment 2 of the present disclosure.

[0023] Figure 8 It is a diagram showing the simulation results of the passband characteristics of the mode conversion structure according to the second embodiment of the present disclosure and the mode conversion structure of the comparative example.

[0024] Fig. 9 It is a perspective view showing a mode conversion structure of a modified example of the second embodiment of the present disclosure.

[0025] Fig.10 It is a side cross-sectional view showing a mode conversion structure of a modified example of the second embodiment of the present disclosure.

[0026] Fig.11 It is a perspective view showing a mode conversion structure according to Embodiment 3 of the present disclosure.

[0027] Fig.12 It is a side sectional view showing a mode conversion structure according to Embodiment 3 of the present disclosure.

[0028] Fig.13 It is a diagram showing the simulation results of the passband characteristics of the mode conversion structure according to the third embodiment of the present disclosure and the mode conversion structure of the comparative example.

[0029] Fig.14 It is a side cross-sectional view showing a mode conversion structure of a modified example of the third embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings as appropriate. However, sometimes an overly detailed description will be omitted. For example, sometimes a detailed description of a well-known matter or a repeated description of a substantially identical structure will be omitted. The reason is to avoid the following description from becoming unnecessarily lengthy and to make it easy for those skilled in the art to understand.

[0031] In addition, the drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0032] In this specification, the positive direction of the Z axis shown in the drawings is referred to as the upper direction, and the negative direction of the Z axis is referred to as the lower direction. In addition, in various drawings, for the sake of ease of reading and observation, some elements such as the side surface of the mode conversion structure (the surface parallel to the YZ plane shown in the drawings) are omitted, and some elements are not drawn to scale.

[0033] (Implementation Method 1)

[0034] <Composition of mode conversion structure>

[0035] Figure 1 is a perspective view showing a mode conversion structure 10 according to Embodiment 1 of the present disclosure, Figure 2 1 is a side cross-sectional view (AA′ cross-sectional view) showing the mode conversion structure 10 .

[0036] like Figure 1 and Figure 2 As shown, the mode conversion structure 10 includes a first dielectric substrate 11 having a microstrip line MSL and a second dielectric substrate 14 having a pillar-walled waveguide PW. Here, the thickness (first thickness) of the first dielectric substrate 11 is different from the thickness (second thickness) of the second dielectric substrate 14 (the thickness of the second dielectric substrate 14 is thicker than the thickness of the first dielectric substrate 11).

[0037] In addition, the thickness of the first dielectric substrate 11 may be replaced by the thickness of the dielectric constituting the first dielectric substrate 11 or the thickness of the microstrip line MSL, and the thickness of the second dielectric substrate 14 may be replaced by the thickness of the dielectric constituting the second dielectric substrate 14 or the thickness of the pillar-walled waveguide PW. In addition, the first dielectric substrate 11 and the second dielectric substrate 14 may be composed of one substrate or different substrates.

[0038] like Figure 1 As shown, the microstrip line MSL includes a first dielectric substrate 11, a line conductor 12, and a GND 13 (first ground conductor). Specifically, the microstrip line MSL is composed of the line conductor 12 and the GND 13 facing each other through a dielectric in the first dielectric substrate 11.

[0039] like Figure 1As shown, the pillar-walled waveguide PW includes a second dielectric substrate 14, a first conductor layer 15, a second conductor layer 16, and a through hole (conducting hole) 17. Specifically, the pillar-walled waveguide PW is composed of the first conductor layer 15 and the second conductor layer (waveguide wide wall or simple wide wall (components constituting the waveguide wide wall or simple wide wall)) 16 which are opposed to each other via a dielectric in the second dielectric substrate 14, and the opposed through holes (waveguide narrow wall or simple narrow wall (components constituting the waveguide narrow wall or simple narrow wall)) 17 which electrically connect these conductor layers. In addition, the through holes 17 are arranged at intervals of less than half the wavelength (λ / 2) of the electromagnetic wave in the signal transmission direction (the propagation direction of the electromagnetic wave (transmission direction); Y direction).

[0040] like Figure 2 As shown, the line conductor 12 and the first conductor layer 15 are connected on the same plane (a plane parallel to the XY plane).

[0041] like Figure 1 and Figure 2 As shown, the through hole (conductive hole) 18 (first through hole) electrically connects the GND 13 and the second conductor layer 16 (the GND 13 and the second conductor layer 16 are electrically connected via the through hole 18). Therefore, unlike the prior art, the GND 13 and the second conductor layer 16 are not connected on the same plane (a plane parallel to the XY plane).

[0042] <Comparative Example>

[0043] Figure 3 is a perspective view showing a mode conversion structure 30 of a comparative example, Figure 4 2 is a side cross-sectional view (AA′ cross-sectional view) showing the mode conversion structure 30. In the mode conversion structure 30, the same elements as those of the mode conversion structure 10 are denoted by the same reference numerals, and portions different from those of the mode conversion structure 10 are described below.

[0044] like Figure 3 and Figure 4 As shown, the mode conversion structure 30 includes a first dielectric substrate 11 having a microstrip line MSL and a second dielectric substrate 14 having a cylindrical waveguide PW. Unlike the mode conversion structure 10, in the mode conversion structure 30, the thickness of the first dielectric substrate 11 is the same as the thickness of the second dielectric substrate 14, the GND 13 and the second conductor layer 16 exist on the same plane (XY plane), and there is no through hole equivalent to the through hole 18. Therefore, it can be considered that the mode conversion structure 30 is an example of utilizing the prior art based on the mode conversion structure disclosed in Patent Document 1.

[0045] <Comparison>

[0046] The inventors of the present invention used electromagnetic field simulation using the finite integration method to analyze the use of Figure 1When the mode conversion structure 10 of Example 1 (Implementation 1) shown in the figure connects a microstrip line with a thickness of 0.1 mm to a cylindrical waveguide with a thickness of 0.2 mm, and when using Figure 3 The mode conversion structure 30 of the comparative example (example using the prior art) shown here compares the radiation power at 300 GHz when connecting a microstrip line with a thickness of 0.2 mm to a cylindrical waveguide with a thickness of 0.2 mm, and the radiation loss.

[0047] Figure 5 : is a graph showing the results of the simulation of the radiation power of the mode conversion structure 10 of Example 1 and the mode conversion structure 30 of the comparative example when the power of 0.5 W is input. Figure 5 It can be seen that the mode conversion structure 10 of Example 1 radiates less power into space and can reduce radiation loss compared with the mode conversion structure 30 of Comparative Example 1. This is because the thickness of the microstrip line of Example 1 is thinner than that of the microstrip line of the comparative example.

[0048] In this way, the mode conversion structure 10 does not need to make the thickness of the microstrip line MSL the same as the thickness of the pillar-walled waveguide PW, so that the transmission loss can be suppressed and the microstrip line MSL and the pillar-walled waveguide PW having different thicknesses on the dielectric substrate can be connected.

[0049] (Implementation Method 2)

[0050] <Composition of mode conversion structure>

[0051] Figure 6 2 is a perspective view showing a mode conversion structure 60 according to a second embodiment of the present disclosure. Figure 7 2 is a side cross-sectional view (AA′ cross-sectional view) showing the mode conversion structure 60. In the mode conversion structure 60, the same elements as those of the mode conversion structure 10 are denoted by the same reference numerals, and portions different from those of the mode conversion structure 10 are described below.

[0052] Different from the mode conversion structure 10, in the mode conversion structure 60, as shown in FIG. Figure 7 As shown, the GND 13 arranged parallel to the line conductor 12 is further extended (overlapped) by about λ / 2 between the first conductor layer 15 and the second conductor layer 16. The GND 13 extends about λ / 2 in the direction of the column wall waveguide PW (positive side of the Y axis) with the end face of the through hole 18 (ZX plane perpendicular to the Y axis) as a reference. When viewed from the Z direction, the through hole 18 is arranged at a distance of about λ / 2 from the end face (end) of the GND 13 connected to the column wall waveguide PW along the propagation direction of the electromagnetic wave (towards the negative direction of the Y axis). Figure 7 In the illustrated mode conversion structure 60 , the GND 13 , the first conductor layer 15 , and the second conductor layer 16 are arranged so as to overlap each other by approximately λ / 2 in the YZ cross section.

[0053] In this way, since the end face of the GND 13 (the end face in contact with the pillar-walled waveguide PW when viewed from the Z direction), the through hole 18 and the second conductor layer 16 constitute a short-circuit stub, power reflection is reduced and the bandpass characteristic is improved.

[0054] <Comparison>

[0055] The inventors of the present invention used electromagnetic field simulation using the finite integration method to analyze and compare Figure 6 The mode conversion structure 60 of the embodiment 2 (implementation mode 2) shown in FIG. Figure 3 The passband characteristics of the mode conversion structure 30 of the comparative example (example utilizing the prior art) are shown.

[0056] Figure 8 3 is a diagram showing the simulation results of the passband characteristics of the mode conversion structure 60 and the mode conversion structure 30. Figure 8 In FIG. 1 , the horizontal axis represents the frequency (unit: GHz), and the vertical axis represents the value of S21 (unit: dB), which is an S parameter representing the bandpass characteristic.

[0057] Depend on Figure 8 It can be seen that, when the frequency is 300 GHz, the passband characteristic of the mode conversion structure 60 is larger than that of the mode conversion structure 30 .

[0058] <Modification>

[0059] Fig. 9 is a perspective view showing a mode conversion structure 90 according to a modified example of the second embodiment of the present disclosure, Fig.10 1 is a side cross-sectional view (AA′ cross-sectional view) showing the mode conversion structure 90 .

[0060] In this variation, if Fig.10 As shown, when viewed from the Z direction (in the XY plane), the main conductor layer (second conductor layer) 16 is extended from the column wall waveguide PW to the direction of the microstrip line MSL (negative direction of the Y axis) by about λ / 2 based on the connection surface of the line conductor 12 and the first conductor layer 15 (ZX plane perpendicular to the Y axis). Based on the structure of the mode conversion structure 60, the positions of the GND 13 and the through hole 18 in the negative direction of the Y axis are offset by about λ / 2 in the negative direction of the Y axis. Fig.10In the mode conversion structure 90 shown, the line conductor 12, GND 13, and the second conductor layer 16 are arranged to overlap by about λ / 2 in the YZ cross section. In this case, when viewed from the Z direction (in the XY plane), the through hole 18 is arranged to be spaced apart from the end face of the GND 13 connected to the pillar-walled waveguide PW along the propagation direction of the electromagnetic wave (toward the negative direction of the Y axis) by about λ / 2. In this structure, similarly, since the end face of the GND 13 (the end face connected to the pillar-walled waveguide PW when viewed from the Z direction), the through hole 18, and the second conductor layer 16 constitute a short-circuit stub, the reflection of the power is reduced and the bandpass characteristic is improved.

[0061] As described above, the through hole 18 may not be arranged directly below the position where the line conductor 12 of the microstrip line MSL is connected to the first conductor layer 15 of the pillar-walled waveguide PW or in the vicinity thereof. The passband characteristic depends on the positional relationship between the GND 13 of the microstrip line MSL, the second conductor layer 16 of the pillar-walled waveguide PW, and the through hole 18.

[0062] (Implementation method 3)

[0063] <Composition of mode conversion structure>

[0064] Fig.11 is a perspective view showing a mode conversion structure 110 according to a third embodiment of the present disclosure. Fig.12 1 is a side cross-sectional view (AA′ cross-sectional view) showing the mode conversion structure 110. In the mode conversion structure 110, the same elements as those of the mode conversion structure 60 are denoted by the same reference numerals, and portions different from those of the mode conversion structure 60 are described below.

[0065] Different from the mode conversion structure 60, in the mode conversion structure 110, as shown in FIG. Fig.11 and Fig.12 As shown, GND111 (second grounding conductor) is provided between GND13 and the second conductor layer 16. The mode conversion structure 110 has GND111 arranged between GND13 and the second conductor layer 16. In addition, when viewed from the Z direction (in the XY plane), GND111 extends from the end face of the through hole 18 (the end face connected to the column wall waveguide PW when viewed from the Z direction) by about 3λ / 4 along the propagation direction of the electromagnetic wave. Therefore, when viewed from the Z direction, the end face of GND13 (the end face connected to the column wall waveguide PW when viewed from the Z direction) and the end face of GND111 (the end face connected to the column wall waveguide PW when viewed from the Z direction) are spaced apart by about λ / 4 in the propagation direction of the electromagnetic wave. Fig.12In the mode conversion structure 110 shown, the first conductor layer 15, GND13 and the second conductor layer 16 are arranged to overlap by about λ / 2 in the YZ cross section, the first conductor layer 15, GND111 and the second conductor layer 16 are arranged to overlap by about 3λ / 4 in the YZ cross section, and GND111 and GND13 are arranged to overlap by about λ / 2 in the YZ cross section.

[0066] In addition, unlike the mode conversion structure 60, as Fig.11 and Fig.12 As shown, the mode conversion structure 110 is provided with a through hole (conductive hole) 112 (second through hole) that electrically connects the GND 111 and the second conductor layer 16. The mode conversion structure 110 includes the through hole 112 that electrically connects the GND 111 and the second conductor layer 16. When viewed from the Z direction, the through hole 112 is arranged at a distance of about λ / 2 from the end face of the GND 111 (the end face that is in contact with the pillar wall waveguide PW when viewed from the Z direction) in the propagation direction of the electromagnetic wave (towards the negative direction of the Y axis).

[0067] As a result, a short-circuit stub composed of GND13 and via 18 and a short-circuit stub composed of GND111 and via 112 are stacked in a step-like manner.

[0068] By disposing the short-circuit stubs at a distance of about λ / 4, the phases of the reflected waves from the short-circuit stubs can be opposite to each other. As a result, the reflected waves cancel each other out, thereby reducing the loss caused by reflection and further improving the bandpass characteristics of the mode conversion structure 110 (connecting portion).

[0069] <Comparison>

[0070] The inventors of the present invention used electromagnetic field simulation using the finite integration method to analyze and compare Fig.11 The mode conversion structure 110 of the embodiment 3 (implementation method 3) shown in FIG. Figure 3 The passband characteristics of the mode conversion structure 30 of the comparative example (example utilizing the prior art) are shown.

[0071] Fig.13 is a diagram showing the simulation results of the passband characteristics of the mode conversion structure 110 and the mode conversion structure 30. Fig.13 In FIG. 1 , the horizontal axis represents the frequency (unit: GHz), and the vertical axis represents the value of S21 (unit: dB).

[0072] from Fig.13 It can be seen that, when the frequency is 300 GHz, the passband characteristic of the mode conversion structure 110 is larger than that of the mode conversion structure 30 .

[0073] <Modification>

[0074] exist Fig.11and Fig.12 In FIG. 1 , an example in which the short-circuited stubs are stacked in two steps is shown, but there is no limitation on the number of steps. Fig.14 As shown in the side sectional view of the mode conversion structure 140 of the modified example of the third embodiment of the present disclosure (equivalent to the AA' sectional view of other drawings), GND 141 and through hole 142 are added, and the short-circuit stubs are stacked into three steps. Of course, GND and through holes may be added in the same way and the short-circuit stubs may be stacked into four or more steps.

[0075] For example, the mode conversion structure can have n (n is an integer greater than 1) GNDs (GND111, GND141, etc.) arranged between GND13 and the second conductor layer 16, and through holes (second through holes; through holes 112, through holes 142, etc.) that electrically connect each of the n GNDs to the second conductor layer 16.

[0076] In addition, when viewed from the Z direction (in the XY plane), the through holes that electrically connect each of the n GNDs to the second conductor layer 16 may be arranged at intervals of about λ / 2 from the end faces of each of the n GNDs (the end faces that are in contact with the pillar wall waveguide PW) along the propagation direction of the electromagnetic wave. For example, Fig.14 As shown, in the case of n=2, when viewed from the Z direction, the through hole 112 electrically connecting the GND 111 and the second conductor layer 16 is arranged at a distance of about λ / 2 from the end face of the GND 111 (the end face in contact with the pillar-walled waveguide PW) along the propagation direction of the electromagnetic wave. In addition, for example, when viewed from the Z direction, the through hole 142 electrically connecting the GND 141 and the second conductor layer 16 may be arranged at a distance of about λ / 2 from the end face of the GND 141 (the end face in contact with the pillar-walled waveguide PW) along the propagation direction of the electromagnetic wave.

[0077] In addition, when viewed from the Z direction, the end faces of the respective GND pairs (end faces connected to the column wall waveguide PW) that are opposite to each other in the (n+1) GNDs composed of the GND 13 and the n GNDs may be spaced apart by about λ / 4 along the propagation direction of the electromagnetic wave. For example, Fig.14 As shown, in the case of n=2, when viewed from the Z direction, the end faces of GND13 and GND111 (the end faces connected to the column wall waveguide PW) are spaced apart by about λ / 4 along the propagation direction of the electromagnetic wave, and GND13 and GND111 are an opposing GND pair. In addition, for example, when viewed from the Z direction, the end faces of GND111 and GND141 (the end faces connected to the column wall waveguide PW) are spaced apart by about λ / 4 along the propagation direction of the electromagnetic wave, and GND111 and GND141 are an opposing GND pair. Fig.14In the mode conversion structure 140 shown, the first conductor layer 15, GND13 and the second conductor layer 16 are arranged to overlap by about λ / 2 in the YZ section, the first conductor layer 15, GND111 and the second conductor layer 16 are arranged to overlap by about 3λ / 4 in the YZ section, the first conductor layer 15, GND141 and the second conductor layer 16 are arranged to overlap by about λ in the YZ section, GND111 and GND13 are arranged to overlap by about λ / 2 in the YZ section, and GND111 and GND141 are arranged to overlap by about 3λ / 4 in the YZ section.

[0078] <Effects of Implementation Methods>

[0079] The mode conversion structure (mode conversion structure 10, 60, 90, 110, 140) of the embodiment of the present disclosure includes: a first dielectric substrate 11 having a microstrip line MSL composed of an opposing line conductor 12 and a GND 13 and having a first thickness; a second dielectric substrate 14 having a pillar-walled waveguide PW having a second thickness thicker than the first thickness, the pillar-walled waveguide PW including an opposing first conductor layer 15 and a second conductor layer 16; and a through hole 18 electrically connecting the GND 13 and the second conductor layer 16. The line conductor 12 and the first conductor layer 15 are connected on the same plane (a plane parallel to the XY plane).

[0080] According to this structure, it is not necessary to make the thickness of the microstrip line the same as that of the pillar-walled waveguide, so that the transmission loss can be suppressed and the microstrip line and the pillar-walled waveguide having different thicknesses can be connected.

[0081] <Summary of Implementation Methods>

[0082] A waveguide according to an embodiment of the present disclosure includes: a first dielectric substrate having a microstrip line composed of a line conductor and a first ground conductor opposite to the line conductor and having a first thickness; a second dielectric substrate having a pillar-walled waveguide having a second thickness thicker than the first thickness, the pillar-walled waveguide including a first conductor layer connected to the line conductor on the same plane and a second conductor layer opposite to the first conductor layer; and a first through hole electrically connecting the first ground conductor and the second conductor layer.

[0083] According to the above configuration, it is not necessary to make the thickness of the microstrip line the same as that of the pillar-walled waveguide, so that the transmission loss can be suppressed and the microstrip line and the pillar-walled waveguide having different thicknesses can be connected.

[0084] In this mode conversion structure, when viewed from a direction perpendicular to the same plane, the first through hole is arranged at a distance of approximately half the wavelength of the electromagnetic wave propagating in the pillar-walled waveguide from the end of the first ground conductor connected to the pillar-walled waveguide along the propagation direction of the electromagnetic wave.

[0085] According to the above configuration, since the end portion of the first ground conductor, the first through hole, and the second conductor layer constitute a short-circuit stub, power reflection is reduced, and the bandpass characteristic can be improved.

[0086] The mode conversion structure further comprises: a second grounding conductor arranged between the first grounding conductor and the second conductor layer; and a second through hole electrically connecting the second grounding conductor and the second conductor layer, wherein the second through hole is arranged to be spaced apart by approximately half the wavelength of the electromagnetic wave along the propagation direction from the end of the second grounding conductor connected to the pillar-walled waveguide when viewed from a direction perpendicular to the same plane, and approximately a quarter of the wavelength of the electromagnetic wave is spaced apart between the end of the first grounding conductor connected to the pillar-walled waveguide and the end of the second grounding conductor connected to the pillar-walled waveguide when viewed from a direction perpendicular to the same plane.

[0087] According to the above configuration, the short-circuited stubs are stacked and reflected waves from the short-circuited stubs are cancelled out, so that the loss due to reflection can be reduced and the bandpass characteristic can be further improved.

[0088] The mode conversion structure further comprises: n grounding conductors arranged between the first grounding conductor and the second conductor layer, wherein n is an integer greater than 1; and second through holes electrically connecting each of the n grounding conductors to the second conductor layer, wherein the second through holes are arranged to be spaced apart by approximately half the wavelength of the electromagnetic wave along the propagation direction from the ends of each of the n grounding conductors connected to the column wall waveguide when viewed from a direction perpendicular to the same plane.

[0089] According to the above configuration, since the short-circuited stub is formed, power reflection is reduced, and the bandpass characteristic can be improved.

[0090] In this mode conversion structure, when observed from a direction perpendicular to the same plane, the ends of each of the following grounding conductor pairs that are connected to the column wall waveguide are spaced apart by approximately one-quarter of the wavelength of the electromagnetic wave, and the grounding conductor pairs are oppositely arranged grounding conductor pairs among the (n+1) grounding conductors including the first grounding conductor and the n grounding conductors.

[0091] According to the above configuration, since the reflected wave from the short-circuited stub is cancelled, the loss due to the reflection can be reduced and the bandpass characteristic can be further improved.

[0092] In this mode conversion structure, when viewed from a direction perpendicular to the same plane, the first ground conductor, the first conductor layer and the second conductor layer are arranged along the propagation direction of the electromagnetic wave propagating in the pillar wall waveguide, overlapping each other by approximately half the wavelength of the electromagnetic wave.

[0093] In this mode conversion structure, when viewed from a direction perpendicular to the same plane, the first ground conductor, the line conductor and the second conductor layer are arranged along the propagation direction of the electromagnetic wave propagating in the pillar-walled waveguide, overlapping each other by approximately half the wavelength of the electromagnetic wave.

[0094] Although the embodiments are described above with reference to the accompanying drawings, the present disclosure is not limited to these examples. As long as one is skilled in the art, it is obvious that various variations or modifications can be thought of within the scope of the claims. It should be understood that these variations or modifications also belong to the technical scope of the present disclosure. In addition, the various constituent elements in the embodiments can be arbitrarily combined within the scope of the present disclosure.

[0095] The disclosed contents of the specification, drawings, and abstract contained in Japanese patent application No. 2022-085966 filed on May 26, 2022 are incorporated herein by reference in their entirety.

[0096] Industrial Applicability

[0097] One embodiment of the present disclosure is useful for a mode conversion structure for connecting a microstrip line and a cylindrical waveguide.

[0098] Description of Reference Numerals

[0099] 10 Mode conversion structure

[0100] 11. First dielectric substrate

[0101] 12-wire conductor

[0102] 13 Grounding conductor

[0103] 14. Second dielectric substrate

[0104] 15 First conductor layer

[0105] 16 Second conductor layer

[0106] 17Through hole (conducting hole)

[0107] 18 through holes (conducting holes)

[0108] 30 Mode conversion structure

[0109] 60 Mode conversion structure

[0110] 90 Mode conversion structure

[0111] 110 Mode conversion structure

[0112] 111 Grounding conductor

[0113] 112 through hole (conducting hole)

[0114] 140 Mode conversion structure

[0115] 141 Grounding conductor

[0116] 142Through hole (conducting hole)

Claims

1. A mode conversion structure, characterized in that: have: A first dielectric substrate having a microstrip line composed of a line conductor and a first ground conductor opposed to the line conductor, and having a first thickness; A second dielectric substrate having a cylindrical wall waveguide having a second thickness thicker than the first thickness, wherein the cylindrical wall waveguide includes a first conductor layer connected to the line conductor on the same plane and a second conductor layer opposite to the first conductor layer; as well as The first through hole electrically connects the first ground conductor and the second conductor layer.

2. The mode conversion structure according to claim 1, wherein: When viewed from a direction perpendicular to the same plane, the first through hole is arranged at a distance of approximately half a wavelength of the electromagnetic wave propagating in the pillar-walled waveguide from the end portion of the first ground conductor in contact with the pillar-walled waveguide along a propagation direction of the electromagnetic wave.

3. The mode conversion structure according to claim 2, wherein: Also available: a second ground conductor disposed between the first ground conductor and the second conductor layer; and a second through hole electrically connecting the second ground conductor and the second conductor layer, When viewed from a direction perpendicular to the same plane, the second through hole is arranged at a distance of approximately half the wavelength of the electromagnetic wave from the end of the second ground conductor connected to the pillar-walled waveguide along the propagation direction. When viewed from a direction perpendicular to the same plane, an end portion of the first ground conductor in contact with the pillar-walled waveguide and an end portion of the second ground conductor in contact with the pillar-walled waveguide are spaced apart by approximately a quarter of the wavelength of the electromagnetic wave.

4. The mode conversion structure according to claim 2, wherein: Also available: n ground conductors arranged between the first ground conductor and the second conductor layer, wherein n is an integer greater than or equal to 1; and a second through hole electrically connecting each of the n ground conductors to the second conductor layer, When viewed from a direction perpendicular to the same plane, the second through holes are arranged at intervals of approximately half the wavelength of the electromagnetic wave from the end portions of each of the n ground conductors in contact with the pillar-walled waveguide in the propagation direction.

5. The mode conversion structure according to claim 4, wherein: When observed from a direction perpendicular to the same plane, the ends of each pair of grounding conductors connected to the column wall waveguide are spaced apart by approximately one-quarter of the wavelength of the electromagnetic wave, and the pairs of grounding conductors are pairs of grounding conductors that are opposite to each other among the n+1 grounding conductors including the first grounding conductor and the n grounding conductors.

6. The mode conversion structure according to claim 1, wherein: When viewed from a direction perpendicular to the same plane, the first ground conductor, the first conductor layer, and the second conductor layer are arranged along a propagation direction of an electromagnetic wave propagating in the pillar-walled waveguide so as to overlap each other by approximately half a wavelength of the electromagnetic wave.

7. The mode conversion structure according to claim 1, wherein: When viewed from a direction perpendicular to the same plane, the first ground conductor, the line conductor, and the second conductor layer are arranged along a propagation direction of an electromagnetic wave propagating in the pillar-walled waveguide so as to overlap each other by approximately half a wavelength of the electromagnetic wave.

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