High-frequency connection structure

Abstract

This high-frequency connection structure connects a high-frequency circuit (121) and a first rectangular waveguide (122), and is provided with a dipole coupler (101) and a second rectangular waveguide (102). The dipole coupler (101) is composed of two linear wires (101a) and (101b) arranged symmetrically in a direction perpendicular to a high-frequency waveguide (transmission) direction, and has a shape similar to that of a well-known dipole antenna. In the second rectangular waveguide (102), the length of the short side is made smaller than that of the first rectangular waveguide (122) in the cross-sectional view, and the dipole coupler (101) is disposed.

Description

High-frequency connection structure

[0001] The present invention relates to a high frequency connection structure.

[0002] Broadband THz waves (electromagnetic waves between 300 GHz and 30 THz) are being considered for application to ultra-high-speed wireless communications such as next-generation wireless communications (beyond 5G). In particular, the 300 GHz band is the frequency band that has the least absorption attenuation during atmospheric propagation, among the THz bands, and can be used to realize transmitters (TX) and receivers (RX) using electronic devices such as CMOS using semiconductors such as SiGe and InP, and therefore research and development is being actively conducted in this band (Non-Patent Document 1, Non-Patent Document 2).

[0003] A 300 GHz band high frequency circuit is usually mounted in a package that uses a waveguide as an interface. A key technology in this configuration is a technology for connecting the high frequency circuit and the waveguide with low loss. As this type of connection technology (high frequency connection structure), a ridge coupler (Patent Document 1) and a probe coupler (Non-Patent Document 3) have been reported.

[0004] As shown in Figure 3 of Patent Document 1, the ridge coupler is a technology that uses a waveguide coupler placed inside a waveguide to gradually convert the mode of propagation through the waveguide into the propagation mode of electromagnetic waves propagating through a high-frequency circuit such as a coplanar line or a microstrip line, thereby connecting the high-frequency circuit and the waveguide with low loss. However, this technology uses bonding wires to connect the waveguide coupler to the transmission line, and the transmission (passing) characteristics and reflection characteristics of the waveguide coupler depend on the diameter, length, and loop of the bonding wire and the shape of the bond that connects the bonding wire, which creates a problem of a tendency for yield to decrease during mounting.

[0005] A probe coupler forms an antenna-like metal wiring at the end of a high-frequency circuit formed in a semiconductor layer such as InP on a dielectric substrate such as silica, and inserts this metal wiring into a waveguide, thereby achieving a low-loss connection between the high-frequency circuit and the waveguide.

[0006] Probe couplers also offer broadband characteristics, but the length of the probe in the signal propagation direction is large, requiring at least half the length of the E-plane of the waveguide. In the 300 GHz band, the length of the probe in the signal propagation direction is approximately 300 to 600 μm. Incorporating such a large coupler into an integrated circuit reduces the area available for arranging the integrated circuit, resulting in increased chip size and ultimately increased chip costs. For this reason, probe couplers are typically formed on a substrate (coupler substrate) separate from the integrated circuit, and this coupler substrate and the integrated circuit are connected by bonding wires. In this case, as with the ridge coupler described above, the bonding wires can cause a problem of reduced yield.

[0007] A dipole coupler is known as a relatively small high-frequency connection structure that does not use bonding wires (Non-Patent Document 4). A dipole coupler is a high-frequency connection structure that has a shape similar to that of a dipole antenna and is composed of two linear wires that are symmetrically arranged in a direction perpendicular to the high-frequency wave-guiding direction.

[0008] A dipole coupler is connected to the end of a high-frequency circuit formed on a semiconductor layer such as InP on a dielectric substrate such as silica, and this dipole coupler is then inserted into a waveguide to achieve a connection between the high-frequency circuit and the waveguide. A low-loss connection is achieved by utilizing the similarity between the electric field formed near the dipole coupler and the mode shape of the electric field formed on the E-plane of the TE10 mode propagating through the waveguide.

[0009] As shown in Figures 7 and 8, the dipole coupler 301 is composed of two quarter-wavelength wirings 301a and 301b in the shape of a dipole antenna. In Figure 7, (a) shows a partial plane parallel to the short side of a waveguide 321 having a rectangular cross section, and (b) shows a cross section parallel to the long side of the waveguide 321 having a rectangular cross section. In Figure 8, (a) shows a partial plane parallel to the short side of the waveguide 321 having a rectangular cross section, and (b) shows a cross section parallel to the long side of the waveguide 321 having a rectangular cross section.

[0010] Since the dipole coupler 301 is arranged perpendicular to the signal propagation direction of the waveguide 321, the length of the coupler required in the signal propagation direction is shorter than that of a probe coupler, and the area of ​​the integrated circuit is less likely to be occupied.

[0011] As the name suggests, currents with a phase difference of 180° flow through the dipole coupler 301, so that the two quarter-wavelength wirings 301a and 301b that make up the dipole coupler 301 can be coupled to a differential transmission line 331 of an integrated circuit, as shown in Fig. 7. In this case, the phase difference between the wirings 301a and 301b is 180°, and the dipole coupler is coupled to the differential transmission line 331. As shown in Fig. 8, if it is desired to make the transmission line 331' of the integrated circuit single-ended, then the wiring 301b on one side can be connected to ground.

[0012] JP 2015-046741 A

[0013] S. Lee et al., "An 80-Gb / s 300-GHz-Band Single-Chip CMOS Transceiver", IEEE Journal of Solid-State Circuits, vol. 54, no. 12, pp. 3577-3587, 2019. PAs and Mixers", IEEE Journal of Solid-State Circuits, vol. 55, no. 9, pp. 2316-2335, 2020. A. Tessmann et al., "Metamorphic HEMT MMICs and Modules Operating Between 300 and 500 GHz", IEEE Journal of Solid-State Circuits, vol. 46, no. 10, pp. 2193-2202, 2011. Ho-Jin Song et al., "Sub-Millimeter and Terahertz-Wave Packaging for Large Chip-Width MMICs", IEEE Microwave and Wireless Components Letters, vol. 26, no. 6, pp. 422-424, 2016.

[0014] However, while dipole couplers are smaller than probe couplers, they still have the problem of being larger than high-frequency interfaces such as RF pads. For example, the size of the coupler required on an integrated circuit is significantly larger than the RF pads used in ridge couplers. For ridge couplers, the area required on an integrated circuit is determined by the area of ​​the RF pads on which wire bonds can be formed, which typically requires a length (in the signal propagation direction) of 100 μm or less and a width (including the ground-strip gate of the RF pad) of 200 μm or less.

[0015] However, in non-patent document 4, dipole couplers are very large, measuring approximately 450 μm. Furthermore, their lengths are often 100 μm or more. Therefore, when a dipole coupler is monolithically formed on a chip on which an integrated circuit is formed, the dipole coupler consumes a large amount of chip area, particularly in the lateral direction. When integrating a dipole coupler with an electronic circuit such as a power amplifier (non-patent document 2) that uses a power combiner and consumes a large amount of chip area in the lateral direction, the electronic circuit and the layout interfere with each other, resulting in a problem of reduced layout flexibility.

[0016] The present invention has been made to solve the above problems, and aims to further miniaturize a high-frequency connection structure consisting of two linear wirings arranged symmetrically in a direction perpendicular to the waveguide direction.

[0017] A high-frequency connection structure according to the present invention is a high-frequency connection structure for connecting a high-frequency circuit and a first rectangular waveguide, and includes: a dipole coupler configured with two linear wirings arranged symmetrically in a direction perpendicular to the wave-guiding direction and connected to the high-frequency circuit; and a second rectangular waveguide in which the length of the short side in cross-section is smaller than that of the first rectangular waveguide and in which the dipole coupler is arranged.

[0018] As described above, according to the present invention, a dipole coupler is disposed in the second rectangular waveguide whose short side is shorter in cross section than the first rectangular waveguide, thereby achieving further miniaturization of a high-frequency connection structure constituted by two linear wirings arranged symmetrically in a direction perpendicular to the wave-guiding direction.

[0019] FIG. 1 is a cross-sectional view showing the configuration of a high-frequency connection structure according to a first embodiment of the present invention. FIG. 2 is a characteristic diagram showing the results of calculating the coupling efficiency when a dipole coupler using two quarter-wavelength wirings is applied to the E-plane of a WR3.4 rectangular waveguide (a) and when it is applied to the E-plane of a narrow rectangular waveguide with a rectangular short side length (width) of 250 μm (b). FIG. 3 is a characteristic diagram showing the transmission characteristics of a high-frequency connection structure in which a rectangular waveguide with a diameter larger than that of the first rectangular waveguide 122 is used as the matching section 103, and a dipole coupler 101 and a second rectangular waveguide 102 are used to connect a high-frequency circuit 121 to a WR3.4 first rectangular waveguide 122. FIG. 4 is a cross-sectional view showing the configuration of a high-frequency connection structure according to a second embodiment of the present invention. FIG. 5 is a cross-sectional view showing the configuration of a high-frequency connection structure according to a third embodiment of the present invention. FIG. 6 is a cross-sectional view showing the configuration of a high-frequency connection structure according to a fourth embodiment of the present invention. FIG. 7 is a cross-sectional view showing the configuration of a conventional high-frequency connection structure. FIG. 8 is a cross-sectional view showing the configuration of a conventional high-frequency connection structure.

[0020] Hereinafter, a high-frequency connection structure according to an embodiment of the present invention will be described.

[0021] First Embodiment First, a high-frequency connection structure according to a first embodiment of the present invention will be described with reference to Fig. 1. This high-frequency connection structure connects a high-frequency circuit 121 and a first rectangular waveguide 122. This high-frequency connection structure includes a dipole coupler 101 and a second rectangular waveguide 102.

[0022] The dipole coupler 101 is composed of two linear wires 101a and 101b arranged symmetrically in a direction perpendicular to the direction of high-frequency wave propagation (transmission), and has a shape similar to that of a well-known dipole antenna. Each of the wires 101a and 101b has an electrical length of about a quarter wavelength of the frequency of the high-frequency wave to be transmitted.

[0023] The dipole coupler 101 is connected to a high-frequency circuit 121. The dipole coupler 101 can be connected to the high-frequency circuit 121 by, for example, a transmission line 123. The dipole coupler 101 can also be integrated on a substrate 131 on which the high-frequency circuit 121 is formed. The substrate 131 can be a well-known mounting substrate for high-frequency circuits.

[0024] In FIG. 1, the dipole coupler 101, the high-frequency circuit 121, and the transmission line 123 are shown as a plan view seen from above in a cross section parallel to the short side of the rectangular waveguide having a rectangular cross section.

[0025] The second rectangular waveguide 102 has a shorter side length in a cross-sectional view (the distance between two side surfaces in a direction perpendicular to the electric field of the electromagnetic field mode of the rectangular waveguide) that is smaller than that of the first rectangular waveguide 122, and the dipole coupler 101 is disposed therein. The wiring 101a and wiring 101b of the dipole coupler 101 are disposed so that their extending directions are the same as the electric field of the electromagnetic field mode propagating through the second rectangular waveguide 102.

[0026] In the first embodiment, a matching unit 103 is further provided. The matching unit 103 is disposed between the first rectangular waveguide 122 and the second rectangular waveguide 102, and matches the impedance of the first rectangular waveguide 122 with the impedance of the second rectangular waveguide 102.

[0027] In the first embodiment, the operating principle is that dipole coupler 101 is inserted into a plane (called the E-plane of the rectangular waveguide) parallel to the electric field of the waveguide mode propagating through the rectangular waveguide, thereby coupling the waveguide mode to dipole coupler 101. Therefore, the width of the high-frequency connection structure is necessarily the same as the width of the E-plane of the rectangular waveguide.

[0028] Tables 1, 2, and 3 show the sizes of commonly used rectangular waveguides for each frequency band. For example, in the 300 GHz band, a rectangular waveguide with a WR3.4 is used, and the width of the E-plane of a WR3.4 is 432 μm. Therefore, if a high-frequency connection structure is designed for a WR3.4 rectangular waveguide in the 300 GHz band, the width will be as large as 432 μm. In fact, this value is very close to the width of the high-frequency connection structure in Non-Patent Document 4.

[0029]

[0030]

[0031]

[0032] As described above, the width of a conventional high-frequency connection structure (dipole coupler) is fixedly determined by the width of the E-plane of a standard rectangular waveguide, and it is difficult to reduce the width.

[0033] In contrast to the conventional structure described above, the horizontal width of the dipole coupler 101 can be reduced by designing it to be inserted into the second rectangular waveguide 102, which has a smaller diameter (narrower width) than the first rectangular waveguide 122 to which the high-frequency circuit 121 is connected. Of course, in this case, the width of the E-plane of the second rectangular waveguide 102 must be larger than the overall width of the high-frequency connection structure. However, the overall width of the dipole coupler 101 constituting the high-frequency connection structure (corresponding to two quarter-wavelength wirings, or roughly half a wavelength) is usually sufficiently smaller than the width of the E-plane. A look at the coupler photograph in Non-Patent Document 4 also reveals that the dipole coupler is smaller than the width of the E-plane (E-plane width) of the rectangular waveguide.

[0034] First, it is necessary to clarify whether dipole coupler 101 can be applied to second rectangular waveguide 102, which has a smaller diameter than first rectangular waveguide 122, to which it is connected. Figure 2 shows the coupling efficiency calculation results for a dipole coupler using two quarter-wavelength wirings applied to the E-plane of a WR3.4 rectangular waveguide (a) and to the E-plane of a narrow rectangular waveguide with a rectangular short side length (width) of 250 μm (b). As shown in Figure 2, the coupling efficiency of the dipole coupler does not deteriorate significantly when applied to a narrow rectangular waveguide, demonstrating that the dipole coupler can be applied to narrow rectangular waveguides.

[0035] Next, the setting of the width of the E-plane of the second rectangular waveguide 102 will be described. The width of the E-plane of the second rectangular waveguide 102 (E-plane width) is set larger than the length (horizontal width) of the dipole coupler 101 in the direction perpendicular to the wave-guiding direction. In other words, the E-plane width is set larger than a quarter wavelength: λ0 / 4k (where λ0 is the wavelength in free space) taking into account the wavelength shortening rate k determined by the relative dielectric constant of the substrate 131 on which the dipole coupler 101 is formed. Furthermore, as the E-plane width is narrowed, the cutoff frequency f c It should also be noted that the following signals will not be able to propagate: Therefore, the E-plane width of the second rectangular waveguide 102 can be reduced to a value Wc at which the desired frequency is not cut off.

[0036] From the above, the E-plane width WE of the second rectangular waveguide 102 can be determined within a range that satisfies "WE > Max(λ / 4k, Wc) (1)." Here, the value of Wc can be easily determined by performing a cutoff analysis of the propagation mode in advance using electromagnetic field analysis. Furthermore, the width of the plane (H-plane) perpendicular to the E-plane of the second rectangular waveguide 102 does not need to be one of those shown in Tables 1, 2, and 3, and can be freely determined within a range that does not result in cutoff at the desired frequency.

[0037] As described above, by using the second rectangular waveguide 102 having a smaller diameter than the first rectangular waveguide 122, it is possible to realize a more compact high-frequency connection structure that connects the high-frequency circuit 121 and the first rectangular waveguide 122 with low loss. In addition to this configuration, by further using the matching section 103, it is possible to improve the high-frequency passing characteristics of the high-frequency connection structure.

[0038] By using the matching section 103, it is possible to match the impedance between the second rectangular waveguide 102 and the first rectangular waveguide 122. For example, when connecting a high frequency wave in the 300 GHz band, it is possible to match the impedance between the second rectangular waveguide 102 and the first rectangular waveguide 122 of WR 3.4 by using a rectangular waveguide having a larger diameter than the first rectangular waveguide 122 as the matching section 103. The length in the wave-guiding direction of the rectangular waveguides used as the second rectangular waveguide 102 and the matching section 103 can be approximately one-quarter wavelength of the frequency to be propagated.

[0039] FIG. 3 shows the transmission characteristics of a high-frequency connection structure in which a rectangular waveguide having a larger diameter than the first rectangular waveguide 122 is used as the matching section 103, and a dipole coupler 101 and a second rectangular waveguide 102 are used to connect the high-frequency circuit 121 and the first rectangular waveguide 122 of WR3.4.

[0040] 3(b), compared to the case (a) in which a dipole coupler 101 is inserted into the first rectangular waveguide 122 to connect the high-frequency circuit 121, by using the second rectangular waveguide 102, it is possible to reduce (improve) the loss at the time of connection with the first rectangular waveguide 122. By using the matching section 103 in addition to the second rectangular waveguide 102, it is possible to further improve the pass characteristics as shown in FIG.

[0041] The matching unit 103 can be a rectangular waveguide having a smaller diameter (E-plane width) than the first rectangular waveguide 122. The matching unit 103 can also be configured from a plurality of rectangular waveguides, each having a different distance (E-plane width) between the two side surfaces in a direction perpendicular to the electric field of the electromagnetic field mode of the rectangular waveguide. By using the matching unit 103 configured from a plurality of rectangular waveguides in this way, the bandwidth over which matching can be achieved can be widened.

[0042] Second Embodiment Next, a high-frequency connection structure according to a second embodiment of the present invention will be described with reference to Fig. 4. This high-frequency connection structure connects a high-frequency circuit 121' and a first rectangular waveguide 122. This high-frequency connection structure includes a dipole coupler 101, a second rectangular waveguide 102, and a matching unit 103. The dipole coupler 101, the second rectangular waveguide 102, and the matching unit 103 are the same as those in the first embodiment described above.

[0043] In the second embodiment, the dimension in the E-plane width direction (chip width) of the rectangular waveguide of the high-frequency circuit 121′ to which the dipole coupler 101 is connected is set to be larger than the E-plane width of the second rectangular waveguide 102. As is well known, chips of high-frequency circuits such as power amplifiers tend to be large in size.

[0044] Dipole coupler 101 is connected to high-frequency circuit 121' by transmission line 123, and dipole coupler 101 and high-frequency circuit 121' are integrated on substrate 131'. Note that in Fig. 4, the dipole coupler 101, high-frequency circuit 121', and transmission line 123 are shown as a plan view seen from above in a cross section parallel to the short side of the rectangular waveguide having a rectangular cross section.

[0045] As described above, when the dipole coupler 101 is integrated on the substrate 131' on which the large-chip-sized high-frequency circuit 121' is mounted, the width of the substrate 131' in the region 131a on which the dipole coupler 101 is mounted is made smaller than the E-plane width of the second rectangular waveguide 102. In this manner, the region 131a of the substrate 131' with the reduced width is inserted into the second rectangular waveguide 102, thereby allowing the dipole coupler 101 to be inserted into the second rectangular waveguide 102. Note that, also in the second embodiment, the matching unit 103 is not necessary, and even in a configuration without the matching unit 103, a more compact high-frequency connection structure can be realized that connects the high-frequency circuit 121' and the first rectangular waveguide 122 with low loss.

[0046] Third Embodiment Next, a high-frequency connection structure according to a third embodiment of the present invention will be described with reference to Fig. 5. This high-frequency connection structure connects a high-frequency circuit 121' and a first rectangular waveguide 122. This high-frequency connection structure includes a dipole coupler 101, a second rectangular waveguide 102, and a matching unit 103. The dipole coupler 101, the second rectangular waveguide 102, and the matching unit 103 are the same as those in the first embodiment described above.

[0047] In the third embodiment, the dimension in the E-plane width direction (chip width) of the rectangular waveguide of the high-frequency circuit 121′ to which the dipole coupler 101 is connected is set to be larger than the E-plane width of the second rectangular waveguide 102. As is well known, chips of high-frequency circuits such as power amplifiers tend to be large in size.

[0048] The dipole coupler 101 is connected to the high-frequency circuit 121′ by a transmission line 123, and the dipole coupler 101 and the high-frequency circuit 121′ are integrated on a substrate 131″. Note that in FIG. 5 , the dipole coupler 101, the high-frequency circuit 121′, and the transmission line 123 are shown as a plan view seen from above in a cross section parallel to the short side of the rectangular waveguide having a rectangular cross section.

[0049] In the second embodiment described above, when the dipole coupler 101 is integrated on the substrate 131' on which the large-chip-sized high-frequency circuit 121' is mounted, the width of the substrate 131' in the region 131a on which the dipole coupler 101 is mounted is made smaller than the E-plane width of the second rectangular waveguide 102, as shown in FIG. 4 . To form such a fine shape on the substrate 131', it is not easy to use dicing technology, and etching technology is used instead. Forming the shape using etching technology requires a long processing time depending on the thickness of the substrate 131'. Furthermore, there are cases where the high-frequency circuit 121' and the dipole coupler 101 are exposed to an etchant for a long time, which may cause a deterioration in their characteristics.

[0050] In contrast to this, in the third embodiment, in an area 141 that sandwiches the area where the dipole coupler 101 is formed, through electrodes 104 are provided that are arranged in a plurality of locations on the substrate 131". The through electrodes 104 are arranged in a plurality of locations on the substrate 131" at intervals that are smaller than a quarter wavelength of the high frequency transmitted between the high frequency circuit and the first rectangular waveguide. Furthermore, each of the through electrodes 104 has a diameter that is smaller than a quarter wavelength of the high frequency transmitted between the high frequency circuit and the first rectangular waveguide. The through electrodes 104 can be formed in a through hole that penetrates the substrate 131". Furthermore, the through electrodes 104 can be formed from a metal layer formed on the tube wall of the through hole, without being formed to fill the through hole.

[0051] 5, the dipole coupler 101, the high-frequency circuit 121', and the transmission line 123 are shown as a plan view seen from above in a cross section parallel to the short side of the rectangular waveguide having a rectangular cross section.

[0052] By arranging the through electrodes 104 at a plurality of locations, this region can be made to have the same boundary conditions as the tube wall of the second rectangular waveguide 102. As a result, the periphery of the dipole coupler 101 integrated on the substrate 131" can be made to have the same boundary conditions as the tube wall of the second rectangular waveguide 102. As a result, by arranging the dipole coupler 101 close to the end of the second rectangular waveguide 102 as shown in FIG. 5, the second rectangular waveguide 102 is made to be in a state where it is virtually extended into the region where the through electrodes 104 are formed. As a result, according to the third embodiment, by arranging the dipole coupler 101 close to the end of the second rectangular waveguide 102, it is possible to couple the waveguide mode of the second rectangular waveguide 102 to the dipole coupler 101 without inserting the dipole coupler 101 into the second rectangular waveguide 102.

[0053] The through electrode 104 can be formed by well-known manufacturing techniques for mounting substrates. According to the third embodiment, there is no need to micro-machine a part of the substrate 131" by special etching, and the high-frequency connection structure can be formed more easily. Note that, also in the third embodiment, the matching section 103 is not necessary, and even in a configuration without the matching section 103, a more compact high-frequency connection structure can be realized that connects the high-frequency circuit 121' and the first rectangular waveguide 122 with low loss.

[0054] Fourth Embodiment Next, a high-frequency connection structure according to a fourth embodiment of the present invention will be described with reference to Fig. 6. This high-frequency connection structure connects a high-frequency circuit 121 and a first rectangular waveguide 122. This high-frequency connection structure includes a dipole coupler 101', a second rectangular waveguide 102, and a matching unit 103. The second rectangular waveguide 102, the matching unit 103, and the high-frequency circuit 121 are the same as those in the first embodiment described above.

[0055] In the fourth embodiment, the widths of the two linear wires 101a' and 101b' constituting the dipole coupler 101' change in the direction away from the center of the dipole coupler 101'. For example, the widths of the wires 101a' and 101b' increase as they move away from the center of the dipole coupler 101'. Note that in FIG. 6, the dipole coupler 101', the high-frequency circuit 121, and the transmission line 123 are shown as a plan view seen from above in a cross section parallel to the short side of the rectangular waveguide having a rectangular cross section.

[0056] The dipole coupler has a characteristic that the bandwidth increases when the width of the two dipole antenna-shaped wirings is increased. The bandwidth and coupling efficiency can be changed by gradually changing the widths of the wirings 101a' and 101b' in a direction away from the center of the dipole coupler 101'. Note that the matching unit 103 is not necessary in the fourth embodiment either, and even if the matching unit 103 is not included, a more compact high-frequency connection structure that connects the high-frequency circuit 121 and the first rectangular waveguide 122 with low loss can be realized. Also, in the fourth embodiment, similar to the third embodiment, a configuration can be adopted in which through electrodes are formed and arranged in multiple locations on a substrate that includes a larger chip-sized high-frequency circuit.

[0057] As described above, according to the present invention, a dipole coupler is disposed in the second rectangular waveguide whose short side is shorter in cross section than the first rectangular waveguide, thereby achieving further miniaturization of a high-frequency connection structure constituted by two linear wirings arranged symmetrically in a direction perpendicular to the wave-guiding direction.

[0058] Some or all of the above-described embodiments may also be described as, but are not limited to, the following supplementary notes.

[0059] [Supplementary Note 1] A high-frequency connection structure for connecting a high-frequency circuit and a first rectangular waveguide, the high-frequency connection structure comprising: a dipole coupler configured by two linear wirings arranged symmetrically in a direction perpendicular to a wave-guiding direction and connected to the high-frequency circuit; and a second rectangular waveguide in which the length of the short side in cross-section is smaller than that of the first rectangular waveguide and in which the dipole coupler is arranged.

[0060] [Supplementary Note 2] In the high-frequency connection structure described in Supplementary Note 1, the dipole coupler is integrated on a substrate on which the high-frequency circuit is formed, and the high-frequency connection structure includes through electrodes arranged at a plurality of locations on the substrate in an area sandwiching the dipole coupler.

[0061] [Appendix 3] In the high-frequency connection structure described in Appendix 2, the through electrodes are arranged and formed at multiple locations on the substrate at intervals smaller than a quarter wavelength of the high-frequency wave transmitted between the high-frequency circuit and the first rectangular waveguide, and each of the through electrodes has a diameter smaller than a quarter wavelength of the high-frequency wave transmitted between the high-frequency circuit and the first rectangular waveguide.

[0062] [Supplementary Note 4] In the high-frequency connection structure described in any one of Supplementary Notes 1 to 3, the width of the two linear wirings constituting the dipole coupler changes along a direction away from the center of the dipole coupler.

[0063] [Supplementary Note 5] The high-frequency connection structure according to any one of Supplementary Notes 1 to 4, further comprising a matching section disposed between the first rectangular waveguide and the second rectangular waveguide, for matching an impedance of the first rectangular waveguide with an impedance of the second rectangular waveguide.

[0064] [Supplementary Note 6] In the high-frequency connection structure described in Supplementary Note 5, the matching section is a high-frequency connection structure composed of a plurality of rectangular waveguides having different spacings between two side surfaces in a direction perpendicular to the electric field of the electromagnetic field mode of the rectangular waveguide.

[0065] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention.

[0066] 101...dipole coupler, 101a, 101b...wiring, 102...second rectangular waveguide, 103...matching section, 121...high frequency circuit, 122...first rectangular waveguide, 123...transmission line, 131...substrate.

Claims

1. A high-frequency connection structure for connecting a high-frequency circuit and a first rectangular waveguide, comprising: a dipole coupler connected to the high-frequency circuit and consisting of two linear wirings arranged symmetrically in a direction perpendicular to the waveguiding direction; and a second rectangular waveguide in which the dipole coupler is arranged and whose short side length in a cross-sectional view is shorter than that of the first rectangular waveguide.

2. A high-frequency connection structure according to claim 1, wherein the dipole coupler is integrated on a substrate on which the high-frequency circuit is formed, and the high-frequency connection structure has through electrodes arranged in a plurality of locations on the substrate in the region sandwiching the dipole coupler.

3. A high-frequency connection structure as claimed in claim 2, wherein the through electrodes are arranged at multiple locations on the substrate at intervals smaller than a quarter wavelength of the high-frequency wave transmitted between the high-frequency circuit and the first rectangular waveguide, and each of the through electrodes has a diameter smaller than a quarter wavelength of the high-frequency wave transmitted between the high-frequency circuit and the first rectangular waveguide.

4. A high-frequency connection structure according to claim 1, wherein the width of the two straight wires constituting the dipole coupler varies in the direction away from the center of the dipole coupler.

5. A high-frequency connection structure according to any one of claims 1 to 4, further comprising a matching section disposed between the first rectangular waveguide and the second rectangular waveguide for matching the impedance of the first rectangular waveguide with the impedance of the second rectangular waveguide.

6. A high-frequency connection structure according to claim 5, wherein the matching section is composed of a plurality of rectangular waveguides having different intervals between two side surfaces in a direction perpendicular to the electric field of the electromagnetic field mode of the rectangular waveguide.

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