Electromagnetic wave converter for highly efficiently converting electromagnetic wave between metal waveguide and intra-substrate waveguide

Abstract

To provide an electromagnetic wave converter which improves the degree of freedom relating to frequency bands.SOLUTION: An electromagnetic wave converter comprises a multilayer substrate 3 in which a plurality of conductive layers and a plurality of dielectric layers are laminated and an intra-substrate waveguide 7 is included and a metal waveguide 4, having one end in contact with one face of the multilayer substrate 3, and converts an electromagnetic wave between the metal waveguide 4 and the intra-substrate waveguide 7. The intra-substrate waveguide 7 is formed by including a conversion position 60 crossing the metal waveguide 4 and an input / output port 71 between two conductor layers in the multilayer substrate 3 and a closing layer 54, which is one of the plurality of conductive layers, is present at a position farther than the intra-substrate waveguide 7 in a view from the metal waveguide 4. Openings 510, 520 and 530 are provided at the conversion position 60 in any conductive layers closer to the metal waveguide 4 than the closing layer 54 in the plurality of conductive layers, and a distal-side back short structure is formed at a distal-side position of the conversion position 60 in a view from the input / output port 71.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The disclosed technology relates to an electromagnetic wave converter that converts electromagnetic waves between a metal waveguide and an in-substrate waveguide with high efficiency. [Background technology]

[0002] An example of a conventional electromagnetic wave converter that converts electromagnetic waves between a metal waveguide and an internal waveguide of a laminated substrate is described in Patent Document 1. The converter in this document is configured by connecting multiple layers of dielectric substrates to a metal waveguide. An opening facing the metal waveguide is formed in the outer conductor layer on the metal waveguide side of the dielectric substrate. A microstrip line is formed in the inner conductor layer. The outer conductor layer on the opposite side to the metal waveguide is a full conductor layer. This outer conductor layer on the opposite side serves as a short-circuit surface, forming a back short. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-193162 A Summary of the Invention [Problem to be solved by the invention]

[0004] The conventional electromagnetic wave converter has a problem that the degree of freedom in selecting the target frequency for conversion is low. This is because the back short length is basically determined by the thickness of the laminated substrate. As a result, the frequency band in which high conversion efficiency can be obtained is limited.

[0005] An object of the present disclosure is to provide an electromagnetic wave converter with a high degree of freedom in terms of frequency bands. [Means for solving the problem]

[0006] An electromagnetic wave converter according to one aspect of the disclosed technology has a laminated substrate in which a plurality of conductive layers and a plurality of dielectric layers are stacked and which has an internal waveguide therein, and a metal waveguide having one end in contact with one surface of the laminated substrate, and converts electromagnetic waves between the metal waveguide and the internal waveguide. The internal waveguide is formed between two conductor layers in the laminated substrate, including a conversion position that intersects with the metal waveguide and an input / output port. A closing layer, which is one of the plurality of conductive layers and has a closing position, is located at a position farther from the internal waveguide in the thickness direction of the laminated substrate as viewed from the metal waveguide. All of the plurality of conductive layers that are closer to the metal waveguide than the closing layer have an opening at the conversion position. A front back-short structure is formed at a position further forward than the conversion position as viewed from the input / output port, which short-circuits all of the conductive layers from the front layer, which is the conductive layer closest to the metal waveguide, to the closing layer.

[0007] In the electromagnetic wave converter in the above embodiment, electromagnetic wave conversion can be performed between the metal waveguide and the in-substrate waveguide inside the laminated substrate. That is, when an electromagnetic wave is input from an input / output port to the in-substrate waveguide, an electromagnetic wave is generated in the metal waveguide and output. Alternatively, when an electromagnetic wave is input to the metal waveguide, an electromagnetic wave is generated in the in-substrate waveguide and output from the input / output port. One of the conductive layers located farther from the in-substrate waveguide as viewed from the metal waveguide is a closed layer, and each conductor layer on the metal waveguide side from that is provided with an opening. Electromagnetic wave conversion is performed in the region where the dielectric is connected by this opening. Here, a forward back-short structure that shorts each conductive layer is formed at a position forward of the conversion position as viewed from the input / output port, so that highly efficient conversion is performed by resonance of the electromagnetic wave. In terms of design, the resonant frequency can be adjusted by the distance from the conversion position to the forward back-short structure.

[0008] In the electromagnetic wave converter of the above embodiment, it is preferable that a rear back-short structure is formed on the opposite side of the conversion position from the front back-short structure, which shorts the conductive layers in a thickness portion other than the thickness range corresponding to the substrate waveguide in the range from the front layer to the closing layer. In this way, there are two levels of resonance frequency of the electromagnetic wave, one due to the front back-short structure and the other due to the rear back-short structure. Therefore, it is possible to perform highly efficient electromagnetic wave conversion in a wide band covering the two levels of resonance frequency.

[0009] In an electromagnetic wave converter having a rear back-short structure, it is preferable that at least one conductive layer, a lower layer, is present between the waveguide in the substrate and the closing layer, and the lower layer has an extension portion that extends further toward the opening at the conversion position than the other conductive layers, which promotes the entry of electromagnetic waves into the rear back-short structure and increases the conversion efficiency.

[0010] In any of the electromagnetic wave converters having a rear back-short structure, the rear back-short structure may be composed of a plurality of interlayer connection vias distributed in the width direction of the in-substrate waveguide, and the positions of the plurality of interlayer connection vias in the longitudinal direction of the in-substrate waveguide may be at least two levels. This makes it possible to control the resonance of electromagnetic waves due to the rear back-short structure in terms of design.

[0011] In the electromagnetic wave converter according to any one of the above aspects, it is preferable that the front back-short structure is disposed at a position further forward than the wall surface of the metal waveguide farther from the input / output port as viewed from the input / output port. In this case, the resonant frequency can be adjusted by changing the position of the front back-short structure in terms of design.

[0012] Similarly, in any of the electromagnetic wave converters having a rear back-short structure, it is preferable that the rear back-short structure is disposed at a position closer to the input / output port than the wall surface of the metal waveguide closer to the input / output port, so that the resonant frequency can be adjusted by changing the position of the rear back-short structure in design. Effect of the Invention

[0013] According to the technical configuration of the present disclosure, an electromagnetic wave converter with a high degree of freedom in terms of frequency bands is provided. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view of an electromagnetic wave converter according to an embodiment; [Diagram 2] FIG. 2 is an exploded perspective view of the electromagnetic wave converter of FIG. [Diagram 3] FIG. 2 is a plan view showing the pattern of a first conductive layer. [Figure 4] FIG. 4 is a plan view showing the pattern of a second conductive layer. [Diagram 5] FIG. 4 is a plan view showing the pattern of a third conductive layer. [Figure 6] FIG. 11 is a plan view showing the pattern of a fourth conductive layer. [Figure 7] 1 is a cross-sectional view of an electromagnetic wave converter according to an embodiment. [Figure 8] FIG. 8 is an enlarged cross-sectional view (part 1) showing a part of FIG. [Figure 9] 2 is an enlarged cross-sectional view (part 2) of the electromagnetic wave converter according to the embodiment; FIG. [Figure 10] 4 is a graph showing frequency characteristics of an electromagnetic wave converter according to an embodiment. [Figure 11] 13 is a graph showing the relationship between the far side back short length and frequency characteristics. [Figure 12] 1 is a graph (part 1) showing the relationship between the thickness of a dielectric layer and frequency characteristics. [Figure 13] 11 is a graph showing the relationship between the rear back short length and frequency characteristics. [Figure 14] 13 is a second graph showing the relationship between the thickness of a dielectric layer and frequency characteristics. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] In this embodiment, the disclosed technology is embodied as a metal waveguide-laminated in-substrate waveguide electromagnetic wave converter 1 shown in FIG. 1. In the following description, the metal waveguide-laminated in-substrate waveguide electromagnetic wave converter 1 is simply referred to as the "electromagnetic wave converter 1." The electromagnetic wave converter 1 in FIG. 1 is a combination of a tubular member 2 and a laminated substrate 3. The tubular member 2 is a metal member having a hollow interior. The hollow region inside the tubular member 2 is a metal waveguide 4. The laminated substrate 3 is formed by laminating a plurality of conductive layers 5 and a plurality of dielectric layers 6 between them.

[0016] 2 shows an exploded view of the tubular member 2 and the laminated substrate 3 in the electromagnetic wave converter 1. In FIG. 2, the laminated substrate 3 is further exploded into each conductive layer 5 and each dielectric layer 6. As shown in FIG. 2, in the example of this embodiment, the number of conductive layers 5 in the laminated substrate 3 is four. In the following description, when the four conductive layers 5 are to be distinguished from one another, they are referred to as conductive layers 51, 52, 53, and 54 in order from the one closest to the tubular member 2. In FIG. 2, a dielectric layer 6 is drawn immediately below the three conductive layers 5 excluding the conductive layer 54, which is the furthest from the tubular member 2.

[0017] The tubular member 2 is a hollow, approximately rectangular parallelepiped member as a whole. The metal waveguide 4 is a through hole formed penetrating the tubular member 2. The metal waveguide 4 is a transmission line inside the tubular member 2. The tubular member 2 is arranged so that the metal waveguide 4 is in a direction perpendicular to the plate surface of the laminated substrate 3. The cross-sectional shape of the tubular member 2 in a plane parallel to the plate surface of the laminated substrate 3 is rectangular. The cross-sectional shape of the metal waveguide 4 in this plane is also rectangular. The four outer surfaces of the tubular member 2 and the four wall surfaces of the metal waveguide 4 are parallel to each other.

[0018] The patterns of each conductive layer 5 of the laminated substrate 3 are shown in Figs. 3 to 6. In each of these figures, the area where the conductor exists is shown with hatching, except for the location of the interlayer vias described below. Furthermore, the area that overlaps with the metal waveguide 4 is shown by a dashed rectangle. However, only the first conductive layer 51 in Fig. 3 is in direct contact with the tubular member 2. In these figures, the up-down direction in the figures corresponds to the short side direction of the metal waveguide 4, and the left-right direction in the figures corresponds to the long side direction of the metal waveguide 4.

[0019] A window 510 is formed in the first conductive layer 51 shown in FIG. 3. The shape of the window 510 is rectangular. The short side direction of the metal waveguide 4 is also the short side direction of the window 510, and the long side direction of the metal waveguide 4 is also the long side direction of the window 510. The short side size of the window 510 is equal to the short side size of the metal waveguide 4. The long side size of the window 510 is smaller than the long side size of the metal waveguide 4. The window 510 is positioned so as to overlap with the metal waveguide 4 in the short side direction. The window 510 is positioned so as to be included within the range of the metal waveguide 4 in the long side direction. The conductive layer 51 is a front layer of the multiple conductive layers 5 that is positioned closest to the tubular member 2.

[0020] A window 520 is formed in the second conductive layer 52 shown in FIG. 4. The shape of the window 520 is also rectangular. The short side and long side directions of the window 520 are similar to those of the window 510 of the conductive layer 51. The short side size of the window 520 is larger than the short side size of the metal waveguide 4. The long side size of the window 520 is equal to the long side size of the window 510 in FIG. 3. The window 520 is positioned so as to extend beyond the range of the metal waveguide 4 both above and below in the short side direction. The window 520 is positioned at the same position as the window 510 in the long side direction.

[0021] A window 530 is formed in the third conductive layer 53 shown in FIG. 5. The shape of the window 530 is also rectangular. The short side direction and long side direction of the window 530 are the same as those of the window 510 and the window 520. The short side direction size of the window 530 is smaller than the short side direction size of the metal waveguide 4. The long side direction size of the window 530 is equal to the long side direction sizes of the windows 510 and 520. The window 530 is located only upward with respect to the range of the metal waveguide 4 in the short side direction, slightly protruding from the range. The window 530 is located at the same position as the windows 510 and 520 in the long side direction.

[0022] The fourth conductive layer 54 shown in Fig. 6 does not have windows formed therein as in the upper three conductive layers 5. A conductor is present over the entire surface of the conductive layer 54, including the area of ​​the metal waveguide 4. The conductive layer 54 is a closed layer. The windows 510, 520, and 530 are openings provided in the conductive layers 51, 52, and 53 on the tubular member 2 side of the conductive layer 54, which is the closed layer.

[0023] 3 to 6 also show the positions of interlayer vias that connect the conductive layers 5 together. The interlayer vias shown here include a front via 61, rear vias 62 and 63, a first lateral via 64, and a second lateral via 65. None of the windows 510, 520, or 530 overlap the positions of these interlayer vias.

[0024] The front via 61 is an interlayer via located above the upper side of the metal waveguide 4 in the figure. The front via 61 connects all four conductive layers 5, namely, conductive layer 51 to conductive layer 54. For this reason, the position of the front via 61 is shown in all of Figures 3 to 6. The distance D1 between the horizontal center line C1 in the figure within the range of the metal waveguide 4 and the center of the front via 61 is the same for all.

[0025] The rear vias 62 and 63 are interlayer vias located below the lower side of the metal waveguide 4 in the figure. The rear via 62 connects all of the four conductive layers 5, the conductive layers 51 to 54. The rear via 63 connects three conductive layers 5, the conductive layers 52 to 54, but is not connected to the conductive layer 51. For this reason, the position of the rear via 62 is shown in all of Figures 3 to 6, but the position of the rear via 63 is not shown in Figure 3 but is shown in Figures 4 to 6. The distance D3 between the center line C1 and the center of the rear via 63 is slightly larger than the distance D2 between the center line C1 and the center of the rear via 62.

[0026] The first lateral via 64 is an interlayer via located near the right and left sides of the metal waveguide 4 in the figure. The first lateral via 64 connects all of the four conductive layers 5, namely, the conductive layer 51 to the conductive layer 54. For this reason, the position of the first lateral via 64 is shown in all of Figures 3 to 6. The first lateral via 64 is located outside the right and left sides of the windows 510, 520, and 530 in Figures 3 to 5.

[0027] The second lateral vias 65 are interlayer vias arranged in a row on both sides of the center line C2 in the vertical direction in the figure within the range of the metal waveguide 4 below the metal waveguide 4 in the figure. The second lateral vias 65 connect only two conductive layers 5, the conductive layer 51 and the conductive layer 52. For this reason, the position of the second lateral vias 65 is shown only in Figures 3 and 4, and is not shown in Figures 5 and 6. In Figures 3 and 4, the distance D4 between the second lateral vias 65 on the right side and the second lateral vias 65 on the left side is slightly smaller than the size of the long side direction of the windows 510 and 520, except for those closest to the metal waveguide 4. The distance between the second lateral vias 65 closest to the metal waveguide 4 is slightly larger than that.

[0028] The cross-sectional structure of the electromagnetic wave converter 1 will be described. Fig. 7 shows a cross-sectional view of the electromagnetic wave converter 1 cut at the position of the center line C1 in Fig. 3. The left-right direction in Fig. 7 corresponds to the direction of the center line C2 in Fig. 3. The left side in Fig. 7 is the lower side in Fig. 3, and the right side in Fig. 7 is the upper side in Fig. 3. In Fig. 7, the metal waveguide 4 appears as a vertical cavity. Its upper end is the first port 41. The center line C3 of the metal waveguide 4 in Fig. 7 is a midline perpendicular to both the center line C1 and the center line C2.

[0029] 7, a window 510 of the conductive layer 51 is located directly below the metal waveguide 4. This allows electromagnetic waves to propagate between the metal waveguide 4 and the dielectric portion inside the laminated substrate 3. A window 520 of the conductive layer 52 and a window 530 of the conductive layer 53 are also located directly below the window 510. This allows all of the dielectrics of the three dielectric layers 6 of the laminated substrate 3 to be connected directly below the metal waveguide 4 without being interrupted by a conductor.

[0030] 7 to the right of the position directly below the metal waveguide 4, all of the conductive layers 51 to 54 are short-circuited by the front via 61. For this reason, electromagnetic waves from the metal waveguide 4 or electromagnetic waves to the metal waveguide 4 are not propagated further to the right of the front via 61.

[0031] 7, the lower three conductive layers 5 of the conductive layer 52 to the conductive layer 54 are short-circuited by the rear via 63. However, the conductive layer 51 and the conductive layer 52 are not short-circuited by the rear via 63. Furthermore, as described in FIG. 4 to FIG. 6, the rear via 62 also short-circuits the conductive layer 52 to the conductive layer 54. The position where the rear via 62 shorts the conductive layer 52 to the conductive layer 54 is a position slightly closer to the metal waveguide 4 than the rear via 63 in the left-right direction in FIG. 7 (the up-down direction in FIG. 4, etc.), and is a position on both sides of the center line C2 and slightly narrower than the distance D4 in the direction perpendicular to the paper surface in FIG. 7 (the left-right direction in FIG. 4, etc.). Therefore, within the range of the conductive layer 52 to the conductive layer 54, the electromagnetic wave from the metal waveguide 4 or the electromagnetic wave to the metal waveguide 4 is not propagated further left than the rear vias 62, 63.

[0032] However, in the upper dielectric layer 6 between the conductive layers 51 and 52, electromagnetic waves can propagate between the position directly below the metal waveguide 4 and the position on the left in FIG. 7. This is because there is no short circuit due to the rear via 63 between the conductive layers 51 and 52, and electromagnetic waves can pass through. The upper dielectric layer 6 to the left of the position where the rear via 63 exists in the lower layer in FIG. 7 (lower in FIG. 3 and FIG. 4) functions as an intra-substrate waveguide 7, which is a transmission line inside the laminated substrate 3. The dielectric within the range defined by the conductive layers 51 and 52, and the rows of second side vias 65 on both sides of the center line C2, functions as the intra-substrate waveguide 7. The left end of the intra-substrate waveguide 7 in FIG. 7 is the second port 71. Hereinafter, the intra-substrate waveguide 7 is also intended to include the portion to the right of the position where the rear vias 62 and 63 exist in the lower layer in FIG. 7 and to the left of the front via 61.

[0033] In the electromagnetic wave converter 1 of this embodiment configured as described above, electromagnetic waves can be exchanged between the metal waveguide 4 and the internal waveguide 7. When an electromagnetic wave traveling downward in Fig. 7 is input from the first port 41 to the metal waveguide 4, an electromagnetic wave traveling leftward in Fig. 7 is generated in the internal waveguide 7 and output from the second port 71. When an electromagnetic wave traveling rightward in Fig. 7 is input from the second port 71 to the internal waveguide 7, an electromagnetic wave traveling upward in Fig. 7 is generated in the metal waveguide 4 and output from the first port 41.

[0034] The first port 41 and the second port 71 are input / output ports where electromagnetic waves are input and output in the electromagnetic wave converter 1. The portion of the dielectric of the laminated substrate 3 directly below the metal waveguide 4 is a conversion position 60 where mutual conversion between the electromagnetic waves of the metal waveguide 4 and the electromagnetic waves of the in-substrate waveguide 7 is performed. When we say the in-substrate waveguide 7, we include the second port 71 and the conversion position 60.

[0035] The conversion position 60 of the electromagnetic wave converter 1 will be further described with reference to Figures 8 and 9. Figure 8 is an enlarged view of a portion of Figure 7, showing a cross section at the center in the width direction of the in-substrate waveguide 7. The aforementioned rear via 63 appears in Figure 8. Figure 9 is a cross section at the same scale as Figure 8, parallel to a cross section, showing a location slightly off the center in the width direction within the range of the in-substrate waveguide 7, i.e., the location of vertical line C4 in Figure 6. The aforementioned rear via 62 appears in Figure 9.

[0036] 8 and 9, as described above, windows are formed in three conductive layers 5, conductive layer 51 to conductive layer 53. However, no window is formed in bottom conductive layer 54. In other words, conductive layer 54 is a closing layer that closes off the area below conversion position 60. Conductive layer 54, which is a closing layer, is located farther from in-substrate waveguide 7 in the thickness direction of laminated substrate 3 when viewed from metal waveguide 4.

[0037] In the laminated substrate 3, the aforementioned multiple front vias 61 are arranged to the right of the conversion position 60 in Fig. 8 and Fig. 9. As a result, a front back-short structure 8 is formed in a position forward of the conversion position 60 as viewed from the second port 71, which shorts all of the conductive layers 5 from the conductive layer 51 closest to the metal waveguide 4 to the conductive layer 54, which is a closed layer. The distance from the center position C1 of the metal waveguide 4 to the center of the front via 61 is the same in Fig. 8 and Fig. 9, and is the distance D1 shown in Fig. 3.

[0038] In the laminated substrate 3, the aforementioned rear vias 62 and 63 are arranged to the left of the conversion position 60 in Fig. 8 and Fig. 9. As a result, a stub structure is formed on the opposite side of the conversion position 60 from the front back-short structure 8, which shorts the conductive layers 5 to each other in a thickness portion other than the thickness range corresponding to the in-substrate waveguide 7 within the range from the conductive layer 51, which is the front layer, to the conductive layer 54, which is the closed layer. In this disclosure, this is referred to as a "rear back-short structure 9". There are two levels of distance from the center position C1 of the metal waveguide 4 to the center of the rear vias 62 and 63, the distance D3 shown in Fig. 4 for the rear via 63, and the distance D2 for the rear via 62.

[0039] In Fig. 8 and Fig. 9, the front via 61 constituting the front back-short structure 8 is disposed at a position further forward than the wall surface 42 on the side farther from the second port 71 in the metal waveguide 4 when viewed from the second port 71. Also, the rear vias 62 and 63 constituting the rear back-short structure 9 are disposed at a position further forward than the wall surface 43 on the side closer to the second port 71 in the metal waveguide 4 when viewed from the second port 71. These are derived from the relationship of the short side direction sizes of the window 520 and the metal waveguide 4 described in the explanation of Fig. 4. Therefore, the dielectric at the conversion position 60 is present on the lower side of the tubular member 2 beyond the part directly below the metal waveguide 4. In designing the laminated substrate 3, the distance D1 can be determined by setting the excess amount E1 from the position of the wall surface 42 at the position of the front via 61. Similarly, the distances D2 and D3 can be determined by setting the excess amounts E2 and E3 from the position of the wall surface 43 at the positions of the rear vias 62 and 63.

[0040] In the electromagnetic wave converter 1 configured as above, as described above, electromagnetic waves can be converted between the metal waveguide 4 and the in-substrate waveguide 7. In this electromagnetic wave conversion, when the distance D1 (back-short length) from the front back-short structure 8 to the center of the metal waveguide 4 (C3 in FIG. 8) corresponds to half the guide wavelength in the in-substrate waveguide 7, resonance occurs due to magnetic field coupling between the in-substrate waveguide 7 and the metal waveguide 4, and the electromagnetic wave is propagated efficiently. In the electromagnetic wave converter 1 of this embodiment, the distance D1 can be freely set in design as described above, so that there is a large degree of freedom in designing the frequency of the electromagnetic wave to be propagated.

[0041] In the electromagnetic wave converter 1, the rear back-short structure 9 also contributes to the propagation efficiency of the electromagnetic wave. This is because resonance occurs even when the rear back-short length corresponds to half the guide wavelength. In addition, the rear back-short length can be freely set in design.

[0042] In the electromagnetic wave converter 1, a back-short structure also exists in the axial direction of the metal waveguide 4. This is because, when viewed from above where the metal waveguide 4 is located in Fig. 7, the area beyond (below) the conversion position 60 where the metal waveguide 4 and the in-substrate waveguide 7 intersect is closed by the conductive layer 54. The back-short length in this back-short structure can be set by the thickness of the laminated substrate 3 in terms of design.

[0043] The frequency characteristics of the electromagnetic wave converter 1 will be explained with reference to Fig. 10. In the graph of Fig. 10, the horizontal axis indicates the frequency of the electromagnetic wave to be propagated, and the vertical axis indicates the transmission level and reflection level of the electromagnetic wave. The transmission level and reflection level indicate the transmission intensity and reflection intensity based on the input intensity. Regarding the transmission intensity, the higher the position in the graph, the closer the transmission intensity, i.e., the output intensity, is to the input intensity, which indicates superior characteristics. Regarding the reflection intensity, the higher the position in the graph, the more components are reflected to the input side without being propagated, which indicates inferior characteristics.

[0044] The example of the graph in FIG. 10 is obtained when the sizes of the various parts of the laminated substrate 3 are set as follows. Distance D1 in Figure 3: 350 μm Distance D2 in Figure 4: 310 μm Distance D3 in Figure 4: 360 μm Thickness of dielectric layer 6: 30 μm for each

[0045] In the example of Figure 10, there are two bottoms B1 and B2 in the reflection intensity. The frequency of bottom B1 (approximately 245 GHz) is the frequency at which resonance occurs due to the front back-short structure 8. The frequency of bottom B2 (approximately 300 GHz) is the frequency at which resonance occurs due to the rear back-short structure 9. At these frequencies, the reflection intensity is significantly reduced due to the high propagation efficiency caused by the resonance.

[0046] Focusing on the transmission intensity in Fig. 10, it can be seen that high transmission intensity is obtained in a wide band from the frequency of bottom B1 to the frequency of bottom B2. This is because there are two levels of frequency at which the reflection intensity decreases, and excellent transmission characteristics are obtained between those frequencies. This is the effect of providing the electromagnetic wave converter 1 with the front back-short structure 8 and the rear back-short structure 9.

[0047] In terms of design, the electromagnetic wave converter 1 can set the bottoms B1 and B2 in FIG. 10 independently. First, an example of setting the bottom B1 will be described. The graph in FIG. 11 is a graph showing the effect on the frequency characteristics by changing the back-short length of the front back-short structure 8. FIG. 11 shows the transmission intensity and reflection intensity when the distance D1 in FIG. 3 is set to three levels of 340 μm, 350 μm, and 360 μm. The sizes of the parts other than the distance D1 are as described above. The horizontal and vertical axes have the same meanings as in FIG. 10 (and also in FIGS. 12 to 14).

[0048] Focusing on the reflection intensity in the graph of Fig. 11, a bottom B21 corresponding to bottom B2 in Fig. 10 is formed at a frequency of about 300 GHz at any level. In the example of Fig. 11, the distance D3 is not changed, so the position of bottom B21 is almost the same at any level.

[0049] In contrast, the bottom corresponding to the bottom B1 in FIG. 10 is divided into bottoms B111, B112, and B113 in FIG. 11 according to the distance D1. When the distance D1 is the shortest at 340 μm, the bottom B111 is very steep, but is relatively close to the position of the bottom B21. When the distance D1 is the longest at 360 μm, the bottom B113 is relatively far from the position of the bottom B21, but has a gentle drop. When the distance D1 is an intermediate 350 μm, the bottom B112 is in an intermediate state. This shows that the resonant frequency on the low frequency side can be controlled by adjusting the back-short length of the front back-short structure 8.

[0050] For this reason, in the transmission characteristics in Figure 11, the following trends are seen in the transmission bands where a nearly constant high transmission intensity is obtained, depending on the distance D1. When the distance D1 is the shortest, the transmission band P11 of the transmission characteristics has high flatness within the region but a somewhat narrow bandwidth. When the distance D1 is the longest, the transmission band P31 has a wide bandwidth but is somewhat inferior in flatness within the region. When the distance D1 is intermediate, the transmission band P21 is in between these two cases. From this, it can be said that the balance between bandwidth and flatness is best when the distance D1 is intermediate.

[0051] The condition of the bottom B1 is not only affected by the distance D1. The thickness of the dielectric in the laminated substrate 3 also affects the bottom B1. The dielectric layer farther from the metal waveguide 4 in particular affects the bottom B1. Specifically, the thickness (T3 in FIG. 8) of the dielectric layer 6 between the conductive layer 53 and the conductive layer 54 mainly affects the characteristics of the front back-short structure 8.

[0052] The graph in Figure 12 shows the effect on frequency characteristics by changing thickness T3. Figure 12 shows the transmission intensity and reflection intensity when thickness T3 in Figure 8 is changed to three levels: 20 μm, 30 μm, and 40 μm. The sizes of each part other than thickness T3 are as described above. In the reflection intensity in the graph in Figure 12, bottom B22, which corresponds to bottom B2 in Figure 10, is almost the same at each level.

[0053] In contrast, the bottom corresponding to bottom B1 in FIG. 10 is divided into bottoms B121, B122, and B123 in FIG. 12 by thickness T3. The situations of these three bottoms are almost the same as the situations of bottoms B111, B112, and B113 in FIG. 11. A thin thickness T3, like a short distance D1, creates a situation that is steep but close to the position of bottom B22. Conversely, a thick thickness T3, like a long distance D1, creates a situation that is far from the position of bottom B22 but has a gradual drop. This shows that the resonance frequency on the low frequency side can be controlled by adjusting the thickness T3 of the dielectric.

[0054] Accordingly, the transmission characteristics in FIG. 12 show a similar tendency to the transmission characteristics in FIG. 11. When thickness T3 is the thinnest, transmission band P12 has high flatness within the region but a somewhat narrow bandwidth. When thickness T3 is the thickest, transmission band P32 has a wide bandwidth but is somewhat inferior in flatness within the region. When thickness T3 is intermediate, transmission band P22 is in between these two cases. This means that the intermediate thickness T3 provides the best balance between bandwidth and flatness.

[0055] Next, an example of setting the bottom B2 will be described. The graph in Fig. 13 shows the effect on frequency characteristics by changing the back-short length of the rear back-short structure 9. Fig. 13 shows the transmission intensity and reflection intensity when the distance D3 in Fig. 4 is set to three levels: 350 μm, 360 μm, and 370 μm. The size of each part other than the distance D3 is as described above, including the distance D2.

[0056] Focusing on the reflection intensity in the graph of Fig. 13, a bottom B13 corresponding to bottom B1 in Fig. 10 is formed at a frequency of about 245 GHz at any level. In the example of Fig. 13, the distance D1 is not changed, so the position of bottom B13 is almost the same at any level.

[0057] In contrast, the bottom corresponding to the bottom B2 in FIG. 10 is divided into bottoms B231, B232, and B233 in FIG. 13 by the distance D3. When the distance D3 is the shortest at 350 μm, the bottom B231 is relatively far from the position of the bottom B13, but the drop is gentle. When the distance D3 is the longest at 370 μm, the bottom B233 is steep, but relatively close to the position of the bottom B13. When the distance D3 is the intermediate 360 ​​μm, the position of the bottom B232 is in an intermediate state. This shows that the resonance frequency on the high frequency side can be controlled by adjusting the back-short length of the rear back-short structure 9.

[0058] Therefore, the transmission characteristics in FIG. 13 also show a tendency according to the distance D3 with respect to the transmission band. Regarding the bandwidth, depending on the positions of the bottoms B231, B232, and B233 described above, the transmission band P31 is the widest when the distance D3 is the shortest, and the transmission band P33 is the narrowest when the distance D3 is the longest. When the distance D3 is intermediate, the transmission band P32 has an intermediate bandwidth. However, although it is difficult to see on the graph, the widest transmission band P31 is somewhat inferior in flatness because the bottom B231 is gentle. Therefore, it can be said that the balance between the bandwidth and flatness is best when the distance D3 is intermediate, 360 μm.

[0059] The condition of the bottom B2 is not only affected by the distance D3. The thickness of the dielectric in the laminated substrate 3 also affects the bottom B2. The bottom B2 is particularly affected by the dielectric layer close to the metal waveguide 4 within the range of the laminated substrate 3 excluding the portion corresponding to the in-substrate waveguide 7. Specifically, the thickness (T2 in FIG. 8) of the dielectric layer 6 between the conductive layer 52 and the conductive layer 53 mainly affects the characteristics of the rear back-short structure 9.

[0060] The graph in Figure 14 shows the effect on frequency characteristics by changing thickness T2. Figure 14 shows the transmission intensity and reflection intensity when thickness T2 in Figure 8 is changed to three levels: 25 μm, 30 μm, and 35 μm. In this example, thickness T3 is also adjusted so that the sum of thickness T2 and thickness T3 is constant at 60 μm. The sizes of each part other than thickness T2 and thickness T3 are as described above. In the reflection intensity in the graph in Figure 14, bottom B14, which corresponds to bottom B1 in Figure 10, is almost the same at each level.

[0061] In contrast, the bottoms corresponding to the bottom B2 in FIG. 10 are divided into bottoms B241, B242, and B243 in FIG. 14 according to the thickness T2. The bottom B241 when the thickness T2 is the thinnest at 25 μm is relatively far from the position of the bottom B14, but has a gentle drop. The bottom B24 when the thickness T2 is the thickest at 35 μm is relatively close to the position of the bottom B14, and also has a gentle drop. The bottom B242 when the thickness T2 is the intermediate 30 μm is intermediate between the two in terms of distance from the bottom B14, and has the steepest drop. This shows that the resonance frequency on the low frequency side can be controlled by adjusting the thickness T2 of the dielectric.

[0062] Therefore, the transmission characteristic in FIG. 14 also shows a tendency according to the thickness T2 with respect to the transmission band. Regarding the bandwidth, the transmission band P41 is the widest when the thickness T2 is the thinnest, and the transmission band P43 is the narrowest when the thickness T2 is the thickest, depending on the positions of the bottoms B241, B242, and B243 described above. The transmission band P32 when the thickness T2 is intermediate has an intermediate bandwidth. However, although it is difficult to see on the graph, the widest transmission band P41 is slightly inferior in flatness because the bottom B241 is gentle. In terms of flatness, the transmission band P32 when the thickness T2 is intermediate is the best. This is because the bottom B242 is steep. Therefore, when considering both the bandwidth and flatness, it can be said that the intermediate thickness T2 of 30 μm is the best.

[0063] The example of the graph in Fig. 10 shown above is an example of the best settings for the distance D1, the distance D2, the thickness T2, and the thickness T3 based on the graphs in Fig. 11 to Fig. 14. This is why a high transmission intensity is obtained in a wide band.

[0064] Further features of the structure shown in Fig. 8 will be described. Here, attention is focused on the conductive layer 53. The conductive layer 53 is one of the lower layers existing between the in-substrate waveguide 7 and the conductive layer 54, which is a closing layer. As described above, a window 530 is also formed in the conductive layer 53 at the conversion position 60 below the metal waveguide 4. However, in Fig. 8, the window 530 is not positioned symmetrically with respect to the center C3 of the metal waveguide 4, but is positioned toward the right (the front back-short structure 8 side).

[0065] 8 (the rear back-short structure 9 side) serves as an extension 531. The extension 531 is a portion of the conductive layer 53 that extends further toward the window 530 than the other conductive layers 51 and 52. The extension 531 affects the ease of entry of electromagnetic waves into the front back-short structure 8 and the rear back-short structure 9.

[0066] The presence of the extension 531 provides the following effects. First, the effect of the rear back-short structure 9 in the portion between the conductive layer 52 and the conductive layer 53 is emphasized to the left of the center C3 in FIG. 8. This is because electromagnetic waves can easily enter this portion. For this reason, when the extension 531 is present, the effect of the rear back-short structure 9 is more pronounced than when the extension 531 is not present. Also, when an electromagnetic wave is input to the metal waveguide 4 and output from the second port 71, the propagation of the electromagnetic wave to the front back-short structure 8 is promoted. For this reason, the effect of the front back-short structure 8 is also emphasized by the extension 531.

[0067] Of course, these effects are more pronounced when the extension 531 is long than when it is short. Therefore, in designing the laminated substrate 3, the effects of the front back-short structure 8 and the rear back-short structure 9 can be adjusted by changing the length of the extension 531.

[0068] In Fig. 8, even on the front back-short structure 8 side, the conductive layers 52 and 53 have protruding portions toward the conversion position 60. These are not intentional, but are unavoidable due to the need to position the front via 61 at a position where the conductive layers 51 to 54 can be reliably short-circuited. Therefore, within the range of the dimensional accuracy and positional accuracy in manufacturing the laminated substrate 3, the smaller the protruding amount of the conductive layers 52 and 53, the better.

[0069] As described above in detail, in the electromagnetic wave converter 1 according to the present embodiment, the in-substrate waveguide 7 is provided inside the laminated substrate 3 which is combined with the metal waveguide 4, and electromagnetic wave conversion is performed between the metal waveguide 4 and the in-substrate waveguide 7. In the laminated substrate 3, the front back-short structure 8 is provided at a position forward of the conversion position 60, so that the electromagnetic wave is efficiently converted and the resonant frequency can be set by the position of the front via 61. Furthermore, by providing the rear back-short structure 9 at a position opposite to the front back-short structure 8 in the laminated substrate 3, efficient conversion of electromagnetic waves in a wide band is possible.

[0070] This embodiment is merely an example and does not limit the disclosed technology in any way. Therefore, the disclosed technology can be improved and modified in various ways without departing from the spirit of the technology. For example, the configuration of the laminated substrate 3 can be modified in various ways in addition to the above.

[0071] In the above description, the laminated substrate 3 has four conductive layers 5 and three dielectric layers 6, but the number of layers is not limited to this. The disclosed technology can be realized even if the laminated substrate 3 has at least four conductive layers 5 and three dielectric layers 6. Of course, the number of layers may be greater. When the number of layers is greater, the in-substrate waveguide 7 may have a thickness equivalent to the thickness of a plurality of dielectric layers 6. Alternatively, the rear back-short structure 9 may have more layers than those shown in the drawings. Further dielectric layers 6 and conductive layers 5 may be laminated below the conductive layer 54, which is a closed layer.

[0072] In the laminated substrate 3 described above, the intra-substrate waveguide 7 is provided at a position closest to the metal waveguide 4 within its entire thickness, but this is not essential. The intra-substrate waveguide 7 may also be provided at a position farthest from the metal waveguide 4 within the entire thickness of the laminated substrate 3, for example, between the conductive layer 53 and the conductive layer 54 in Fig. 8. The intra-substrate waveguide 7 may also be provided at an intermediate position within the entire thickness of the laminated substrate 3, for example, between the conductive layer 52 and the conductive layer 53 in Fig. 8.

[0073] The arrangement of the interlayer vias constituting the front back-short structure 8 and the rear back-short structure 9 can also be modified. As for the interlayer vias constituting the rear back-short structure 9, an example has been disclosed in which there are multiple levels of positions in the longitudinal direction of the in-substrate waveguide 7, such as the rear vias 62, 63 shown in FIG. 4 and the like. This reduces the steepness of the bottom B2 in FIG. 10 to some extent. However, this is not essential, and the rear vias 62, 63 can also be arranged on a straight line. Alternatively, the positions of the rear vias 62, 63 in the longitudinal direction of the in-substrate waveguide 7 can be three or more levels.

[0074] Regarding the interlayer vias constituting the front back-short structure 8, an example has been disclosed in which the front via 61 is arranged in a straight line as shown in Fig. 4. However, this is not essential, and multiple front vias 61 can also be arranged in a zigzag pattern as in the rear vias 62 and 63.

[0075] [Preliminary Claim 1] 5. The electromagnetic wave converter according to claim 4, The electromagnetic wave converter, wherein the front back-short structure is disposed at a position further forward than a wall surface of the metal waveguide that is farther from the input / output port when viewed from the input / output port.

[0076] [Preliminary Claim 2] An electromagnetic wave converter according to claim 4 or auxiliary claim 1, or an electromagnetic wave converter according to claim 5, comprising the features of claim 2, The electromagnetic wave converter, wherein the rear back-short structure is disposed at a position closer to the input / output port than a wall surface of the metal waveguide closer to the input / output port. [Explanation of symbols]

[0077] 1 Electromagnetic wave converter 53 Conductive layer 2 Tubular member 54 Conductive layer 3 Laminated board 60 conversion position 4 Metallic Waveguide 61 Via 5 Conductive layer 62 Rear via 6 Dielectric layer 63 Back via 7 In-substrate waveguide 64 First side via 8 Back short structure 65 Second side via 9 Rear back short structure 71 Second port 42 Wall 510 Window 43 Wall 520 Window 51 Conductive layer 530 Window 52 Conductive layer 531 Extension

Claims

1. An electromagnetic wave converter comprising: a laminated substrate in which a plurality of conductive layers and a plurality of dielectric layers are laminated, and an in-substrate waveguide therein; and a metal waveguide, one end of which is in contact with one surface of the laminated substrate, for converting electromagnetic waves between the metal waveguide and the in-substrate waveguide, the in-substrate waveguide is formed between two conductor layers in the laminated substrate, the in-substrate waveguide including a transition position intersecting the metal waveguide and an input / output port; a closing layer, which is one of the plurality of conductive layers and has the conversion position closed, is present at a position farther from the metal waveguide than the in-substrate waveguide in a thickness direction of the laminated substrate, Any of the plurality of conductive layers that is closer to the metal waveguide than the closing layer has an opening at the conversion position; An electromagnetic wave converter in which a forward back-short structure is formed at a position further forward than the conversion position as viewed from the input / output port, which shorts all of the conductive layers from the front layer, which is the one of the plurality of conductive layers closest to the metal waveguide, to the closing layer.

2. 2. The electromagnetic wave converter according to claim 1, An electromagnetic wave converter in which a rear back-short structure is formed on the opposite side of the conversion position from the front back-short structure, shorting the conductive layers together in a thickness portion outside the thickness range corresponding to the internal waveguide within the range from the front layer to the closing layer.

3. 3. The electromagnetic wave converter according to claim 2, At least one lower layer is present between the substrate waveguide and the closing layer, the lower layer being the conductive layer; The lower layer has an extension extending beyond the other conductive layers relative to the transduction location opening.

4. 4. The electromagnetic wave converter according to claim 2, the rear backshort structure is formed of a plurality of interlayer connection vias arranged in a distributed manner in a width direction of the in-substrate waveguide, An electromagnetic wave converter in which the interlayer connection vias are positioned at at least two levels in the longitudinal direction of the substrate-internal waveguide.

5. 4. An electromagnetic wave converter according to claim 1, The electromagnetic wave converter, wherein the front back-short structure is disposed at a position further forward than a wall surface of the metal waveguide that is farther from the input / output port when viewed from the input / output port.

6. 4. The electromagnetic wave converter according to claim 2, The electromagnetic wave converter, wherein the rear back-short structure is disposed at a position closer to the input / output port than a wall surface of the metal waveguide that is closer to the input / output port.

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