Mounting structure, antenna module, and communication device

Abstract

A mounting structure (1) includes: a dielectric body (10); a ground electrode (14) provided on the dielectric body; a first line (11) provided on the dielectric body so as to face the ground electrode; a second line (12) provided on the dielectric body so as to face the ground electrode, the second line (12) being positioned between the first line and the ground electrode in the normal direction of the dielectric body; a connecting conductor (15) for connecting the first line and the second line; and a stub (13) extending from a portion, connected to the connecting conductor, of the first line, and provided on the dielectric body so as to face the ground electrode and the second line. The thickness of the first line in the normal direction is greater than the thickness of the second line in the normal direction. The second line extends in the same direction as the first line. The stub extends in the extension direction in which the second line extends. When the dielectric body is viewed from the normal direction, at least a portion of the stub overlaps the second line in the extension direction.

Description

Mounting structure, antenna module, and communication device

[0001] The present disclosure relates to a mounting structure for a transmission line that transmits a signal, an antenna module including the mounting structure, and a communication device equipped with the antenna module.

[0002] Conventionally, a mounting structure of transmission lines for transmitting signals between multiple lines of different thicknesses has been known. In such a mounting structure, the difference in capacitance between the thicker transmission line and the thinner transmission line may cause a difference in impedance due to the difference in distance between the thicker transmission line and the ground electrode and the thinner transmission line and the ground electrode, which may increase transmission loss between the transmission lines.

[0003] In this regard, Japanese Patent Laid-Open Publication No. 2006-128868 (Patent Document 1) discloses a connection circuit in which a thicker transmission line and a thinner transmission line provided on a conductor chassis are connected by a connection conductor, and a high-impedance line is further connected in parallel to the thinner transmission line.

[0004] Japanese Patent Application Laid-Open No. 2006-128868

[0005] According to the connection circuit disclosed in JP 2006-128868 A, the difference in capacitance caused by the difference between the distance between the thicker transmission line and the conductor chassis and the distance between the thinner transmission line and the conductor chassis can be adjusted by a high impedance line, and the impedance can be matched between the thicker and thinner transmission lines.

[0006] However, the impedance matching technology disclosed in JP 2006-128868 A is applicable only to a structure in which two transmission lines of different thicknesses are provided on the main surface of a conductor chassis, and therefore it is not possible to achieve good impedance matching in a structure in which the thinner transmission line is provided in an inner layer of a dielectric and the thicker transmission line and the thinner transmission line are connected between the dielectric layers.

[0007] The present disclosure has been made to solve such problems, and its purpose is to provide a technology that can achieve good impedance matching in a structure in which multiple transmission lines of different thicknesses are connected between dielectric layers.

[0008] A mounting structure of a transmission line for transmitting a signal according to the present disclosure includes a dielectric, a ground electrode provided on the dielectric, a first line provided on the dielectric opposite the ground electrode, a second line provided on the dielectric opposite the ground electrode between the first line and the ground electrode in a normal direction of the dielectric, a connecting conductor connecting the first line and the second line, and a stub extending from a connection portion of the connecting conductor of the first line and provided on the dielectric opposite the ground electrode and the second line. The thickness of the first line in the normal direction is greater than the thickness of the second line in the normal direction. The second line extends in the same direction as the extension of the first line. The stub extends in the extension direction of the second line. When the dielectric is viewed from the normal direction, at least a portion of the stub overlaps with the second line in the extension direction.

[0009] In the mounting structure according to the present disclosure, a stripline is formed between a microstripline formed by a first line and a ground electrode and a microstripline formed by a second line and a ground electrode, with the second line sandwiched between a ground electrode and a stub. By adjusting the impedance using such a stripline, good impedance matching can be achieved even in a structure in which a thicker first line and a thinner second line are connected between dielectric layers.

[0010] FIG. 1 is a perspective view of a mounting structure of a transmission line according to a first embodiment. FIG. 2 is a cross-sectional view of the mounting structure according to the first embodiment. FIG. 3 is a diagram showing the configuration of an antenna device including the mounting structure according to the first embodiment. FIG. 4 is a diagram showing the configuration of an antenna module and a communication device including the antenna device according to the first embodiment. FIG. 5 is a diagram showing the configuration of an antenna device according to a second embodiment. FIG. 6 is a diagram showing the configuration of an antenna device according to a third embodiment. FIG. 7 is a diagram showing the configuration of an antenna device according to a fourth embodiment. FIG. 8 is a diagram showing the configuration of an antenna device according to a fifth embodiment. FIG. 9 is a perspective view of a mounting structure of a transmission line according to a modified example. FIG. 10 is a cross-sectional view of a mounting structure of a transmission line according to a modified example.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0012] <First Embodiment> [Mounting structure] A mounting structure 1 of a transmission line according to a first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a perspective view of the mounting structure 1 of a transmission line according to the first embodiment. Figure 2 is a cross-sectional view of the mounting structure 1 according to the first embodiment. For example, the mounting structure 1 is a mounting board that constitutes a transmission line that transmits high-frequency signals.

[0013] 1 and 2 , the mounting structure 1 includes a dielectric 10, a ground electrode 14, a first line 11, a second line 12, and a connecting conductor 15. In the following, the configuration of the mounting structure 1 will be described by defining an axis along the width direction of the dielectric 10 as the X-axis, an axis along the length direction of the dielectric 10 as the Y-axis, and an axis along the height direction (normal direction) of the dielectric 10 as the Z-axis.

[0014] The dielectric 10 is a multilayer resin substrate formed by laminating multiple resin layers. The dielectric 10 is formed of a resin such as low temperature co-fired ceramics (LTCC), epoxy, or polyimide. Note that the dielectric 10 may also be formed of other resins, such as liquid crystal polymer (LCP), a fluorine-based resin having a lower dielectric constant, or ceramics other than LTCC.

[0015] The ground electrode 14 is provided in an inner layer of the dielectric 10. The ground electrode 14 has a flat plate shape along the XY plane.

[0016] The first line 11 is provided on the dielectric 10 facing the ground electrode 14. In the example shown in FIGS. 1 and 2 , the first line 11 is provided on the main surface 10A of the dielectric 10. The first line 11 has a rectangular parallelepiped shape and extends in the Y-axis direction on the main surface 10A of the dielectric 10. As shown in FIG. 2 , the mounting structure 1 forms a microstrip line 71 by the first line 11 and the ground electrode 14.

[0017] The second line 12 is provided in an internal layer of the dielectric 10 between the first line 11 and the ground electrode 14 in the Z-axis direction of the dielectric 10, facing the ground electrode 14 and the first line 11. Specifically, the second line 12 is provided in an internal layer of the dielectric 10 located between the main surface 10A of the dielectric 10 on which the first line 11 is provided and the internal layer of the dielectric 10 on which the ground electrode 14 is provided. The second line 12 extends in the positive direction of the Y-axis, which is the same direction as the extension of the first line 11. As shown in FIG. 2 , the mounting structure 1 includes the second line 12 and the ground electrode 14 to form a microstrip line 72.

[0018] As shown in FIG. 1 , an end of the first line 11 is connected to an electrode plate 20. The electrode plate 20 receives a high-frequency signal from a power supply wiring provided on another substrate (not shown) and transmits it to the mounting structure 1. A connecting conductor 15 is connected to the side of the first line 11 that is not connected to the electrode plate 20. The first line 11 is connected to the second line 12 via the connecting conductor 15. Specifically, the connecting conductor 15 is provided inside the dielectric 10 so as to extend in the Z-axis direction across the main surface 10A of the dielectric 10 on which the first line 11 is provided and the internal layer of the dielectric 10 on which the second line 12 is provided. The end of the second line 12 on the side not connected to the connecting conductor 15 is connected to a radiation electrode (not shown) that radiates a high-frequency signal.

[0019] That is, the high frequency signal transmitted via the electrode plate 20 is transmitted through the first line 11, the connecting conductor 15, and the second line 12, and is radiated by the radiation electrode (not shown).

[0020] The thickness of the first line 11 in the Z-axis direction (dimension in the Z-axis direction) is greater than the thickness of the second line 12 in the Z-axis direction (dimension in the Z-axis direction). Furthermore, when the main surface 10A of the dielectric 10 is viewed from the Z-axis direction, the width of the first line 11 (dimension in the X-axis direction) is greater than the width of the second line 12 (dimension in the X-axis direction).

[0021] In this way, since the first line 11 is a line having a cross section (X-Z cross section) of a certain size, it is stably conductive with the electrode plate 20 and can receive the high-frequency signal transmitted from the electrode plate 20 well while minimizing transmission loss, and can transmit the received high-frequency signal to the second line 12 while minimizing transmission loss.

[0022] On the other hand, the second line 12 is a line having a smaller cross section (X-Z cross section) than the first line 11, so even if the second line 12 is provided inside the dielectric 10, there is no need to increase the size of the dielectric 10 to accommodate the second line 12. This makes it possible to reduce the size of the dielectric 10.

[0023] When the main surface 10A of the dielectric 10 is viewed from the Z-axis direction, the dimension of the cross section (X-Y cross section) of the connecting conductor 15 is wider than the width (dimension in the X-axis direction) of the second line 12 and narrower than the width (dimension in the X-axis direction) of the first line 11. In the example shown in Fig. 1, the connecting conductor 15 has a cylindrical shape, and the diameter of the cross section (X-Y cross section) of the connecting conductor 15 is wider than the width (dimension in the X-axis direction) of the second line 12 and narrower than the width (dimension in the X-axis direction) of the first line 11.

[0024] This allows the manufacturer, when connecting the first line 11 and the second line 12 using the connecting conductor 15, to easily connect the connecting conductor 15 to the first line 11 within the range of the width of the first line 11 (dimension in the X-axis direction), and also allows the manufacturer to easily connect the second line 12 to the connecting conductor 15 within the range of the cross section (X-Y cross section) of the connecting conductor 15.

[0025] In the mounting structure 1 configured as described above, the distance between the first line 11 and the ground electrode 14 in the microstrip line 71 is different from the distance between the second line 12 and the ground electrode 14 in the microstrip line 72. In the example shown in Figures 1 and 2, the distance between the second line 12 and the ground electrode 14 in the microstrip line 72 is shorter than the distance between the first line 11 and the ground electrode 14 in the microstrip line 71. This increases the capacitance component in the microstrip line 72 compared to the microstrip line 71, which can cause impedance mismatching between the transmission line that constitutes the microstrip line 71 and the transmission line that constitutes the microstrip line 72.

[0026] Furthermore, due to the difference in thickness between the first line 11 and the second line 12, an impedance mismatch may occur between the transmission line constituting the microstrip line 71 and the transmission line constituting the microstrip line 72.

[0027] Therefore, the mounting structure 1 according to embodiment 1 is configured to be able to achieve good impedance matching between the transmission line constituting the microstrip line 71 and the transmission line constituting the microstrip line 72 by using a stub 13 extending from the connection portion of the connecting conductor 15 in the first line 11.

[0028] Specifically, in the mounting structure 1, a connecting conductor 15 is connected midway along the first line 11, and a portion of the first line 11 extending from the connection portion of the connecting conductor 15 functions as a stub 13. That is, the conductor constituting the stub 13 is the same as the conductor constituting the first line 11. The stub 13, which is a portion of the first line 11, is provided on the main surface 10A of the dielectric 10 facing the ground electrode 14 and the second line 12, and extends in the extension direction of the second line 12 (positive direction of the Y-axis). The end of the stub 13 opposite the connection portion of the connecting conductor 15 (positive direction of the Y-axis) is an open end. That is, the stub 13 is configured as an open stub.

[0029] The length of the portion of the first line 11 that does not function as the stub 13 in the Y-axis direction is shorter than the length of the portion that functions as the stub 13 in the Y-axis direction and the length of the second line 12 in the Y-axis direction. In the Z-axis direction, the distance between the second line 12 and the stub 13 is the same as the distance between the second line 12 and the ground electrode 14.

[0030] Because the stub 13 is part of the first line 11, the thickness of the stub 13 in the Z-axis direction (dimension in the Z-axis direction) is the same as the thickness of the first line 11 in the Z-axis direction (dimension in the Z-axis direction) and is thicker than the thickness of the second line 12 in the Z-axis direction (dimension in the Z-axis direction). Furthermore, when the main surface 10A of the dielectric 10 is viewed from the Z-axis direction, the width of the stub 13 (dimension in the X-axis direction) is wider than the width of the second line 12 (dimension in the X-axis direction).

[0031] When the main surface 10A of the dielectric 10 is viewed from the Z-axis direction, at least a portion of the stub 13 overlaps with the second line 12 in the extension direction (Y-axis direction) of the second line. For example, as shown in Fig. 1 , when the main surface 10A of the dielectric 10 is viewed from the Z-axis direction, the stub 13 completely covers the second line 12 in the width direction (X-axis direction).

[0032] The mounting structure 1 configured as described above has a stripline 73 formed by sandwiching the second line 12 between the ground electrode 14 and the stub 13 between the microstripline 71 and the microstripline 72 in the Y-axis direction.

[0033] By configuring a stripline 73 using a stub 13 in the transmission path from the microstripline 71 to the microstripline 72, the mounting structure 1 can adjust the impedance so that no impedance mismatch occurs between the transmission line that constitutes the microstripline 71 and the transmission line that constitutes the microstripline 72.

[0034] Specifically, the portion of the second line 12 that overlaps with the stub 13 in the Y-axis direction constitutes a strip line 73, and the impedance of the transmission line that constitutes the strip line 73 is smaller than the impedance of the transmission line that constitutes the microstrip line 71 using the first line 11. On the other hand, the portion of the second line 12 that does not overlap with the stub 13 in the Y-axis direction constitutes a microstrip line 72, and the impedance of the transmission line that constitutes the microstrip line 72 is the same as the impedance of the transmission line that constitutes the microstrip line 71 using the first line 11.

[0035] For example, if the impedance of the transmission line that constitutes microstrip line 71 is designed to be 50 Ω, without strip line 73, the impedance of the transmission line that constitutes microstrip line 72 would be smaller than 50 Ω. However, in mounting structure 1, by adjusting the impedance using strip line 73, the impedance of the transmission line that constitutes microstrip line 72 can be made 50 Ω, the same as the impedance of the transmission line that constitutes microstrip line 71.

[0036] As described above, even if the mounting structure 1 of embodiment 1 is configured to connect the first line 11 and the second line 12, which have different thicknesses, using the connecting conductor 15 between the layers of the dielectric 10, it is possible to achieve good impedance matching and suppress an increase in transmission loss.

[0037] The thickness of the stub 13 in the Z-axis direction (the dimension in the Z-axis direction) is the same as the thickness of the first line 11 in the Z-axis direction (the dimension in the Z-axis direction), and therefore, when the stub 13 is regarded as a transmission line, the impedance thereof is equal to the impedance of the first line 11. This allows the mounting structure 1 to suppress unwanted radiation from the stub 13 between the first line 11 and the stub 13.

[0038] When the main surface 10A of the dielectric 10 is viewed from the Z-axis direction, the width of the stub 13 (dimension in the X-axis direction) is wider than the width of the second line 12 (dimension in the X-axis direction), so the mounting structure 1 can effectively make the stub 13 function as a ground electrode for the second line 12 in the stripline 73.

[0039] In the Z-axis direction, the distance between the second line 12 and the stub 13 is the same as the distance between the second line 12 and the ground electrode 14, so the mounting structure 1 can effectively adjust the impedance using the strip line 73.

[0040] [Antenna Device] The antenna device 101 according to the first embodiment will be described with reference to Fig. 3. Fig. 3 is a diagram showing the configuration of the antenna device 101 including the mounting structure 1 according to the first embodiment.

[0041] 3, the antenna device 101 is a microstrip antenna (patch antenna) that includes the mounting structure 1 and a radiation electrode 31. The radiation electrode 31 is a flat electrode that radiates a high-frequency signal transmitted from the mounting structure 1 as a radio wave.

[0042] The radiation electrode 31 is provided on the dielectric 10 constituting the mounting structure 1, and is connected to the second line 12 via a connecting conductor (not shown). The point of the radiation electrode 31 connected to the second line 12 is a feeding point 311. Specifically, one end of the second line 12 in the Y-axis direction is connected to the first line 11 via a connecting conductor 15, and the other end of the second line 12 in the Y-axis direction is connected to the second line 12 via a connecting conductor (not shown). The other end of the second line 12 connected to the radiation electrode 31 is a portion that constitutes the microstrip line 72 without including the stub 13. As a result, the stub 13 is separated from the radiation electrode 31 by a predetermined distance and does not affect the radiation of high-frequency signals by the radiation electrode 31.

[0043] When the radiation electrode 31 is viewed from the Z-axis direction, the length A1 of the radiation electrode 31 in a direction connecting the feed point 311 and the center point 312 (for example, the Y-axis direction) is ½ of the wavelength of a high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 101. In other words, the length A1 of the radiation electrode 31 in the Y-axis direction is ½ of the wavelength of a high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 101.

[0044] The length L of the stub 13 is ¼ of the wavelength of a high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 101. That is, the length L of the stub 13 is ¼ of the wavelength of a high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 101. From another perspective, the length L of the stub 13 is within ±30% of ½ of the length A1 of the radiation electrode 31 in the Y-axis direction. Note that the frequency band supported by the antenna device 101 may be, for example, millimeter-wave radio waves with a center frequency of 28 GHz, 39 GHz, or 60 GHz, or may be radio waves in another frequency band.

[0045] In the antenna device 101 configured as described above, a high-frequency signal transmitted from the electrode plate 20 is transmitted from the first line 11 to the second line 12 while suppressing transmission loss, using the first line 11 and the second line 12 of the mounting structure 1 that have been impedance-matched. The high-frequency signal transmitted to the second line 12 is transmitted from the second line 12 to the radiation electrode 31 and is radiated to the outside by the radiation electrode 31.

[0046] This allows the antenna device 101 to receive high-frequency signals from the electrode plate 20 transmitted via the first line 11 and the second line 12 of the mounting structure 1 while minimizing transmission loss and to radiate them efficiently.

[0047] [Antenna Module, Communication Device] The antenna module 200 and communication device 300 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram showing the configuration of the antenna module 200 and communication device 300 including the antenna device 101 according to the first embodiment. The communication device 300 is, for example, a mobile terminal such as a mobile phone, a smartphone, or a tablet, or another personal computer (PC) equipped with a communication function.

[0048] 4 , the antenna module 200 includes the mounting structure 1, an antenna device 101 including a radiation electrode 31 that radiates a high-frequency signal transmitted from the mounting structure 1, and an RFIC (Radio Frequency Integrated Circuit) 120 that supplies a high-frequency signal to the antenna device 101. A communication device 300 is equipped with the antenna module 200. Specifically, the communication device 300 includes the antenna module 200 and a baseband IC (Integrated Circuit) (hereinafter also referred to as "BBIC") 130 that configures a baseband signal processing circuit.

[0049] The communication device 300 upconverts a signal transmitted from the BBIC 130 to the antenna module 200 into a high-frequency signal and radiates the high-frequency signal from the antenna device 101. The communication device 300 also downconverts a high-frequency signal received by the antenna device 101 and processes it using the BBIC 130.

[0050] As described above, the antenna device 101 including the transmission line mounting structure 1 according to the first embodiment can be used in the antenna module 200 mounted on the communication device 300 such as a mobile terminal.

[0051] <Second Embodiment> An antenna device 102 according to a second embodiment will be described with reference to Fig. 5. Regarding the antenna device 102 according to the second embodiment, only the parts that are different from the antenna device 101 according to the first embodiment will be described, and a description of the other parts will be omitted. Like the antenna device 101 according to the first embodiment, the antenna device 102 according to the second embodiment includes the mounting structure 1 described with reference to Figs. 1 and 2. Fig. 5 is a diagram showing the configuration of the antenna device 102 according to the second embodiment.

[0052] 5, the antenna device 102 is a planar inverted F antenna (PIFA) that includes the mounting structure 1 and a radiation electrode 32. The radiation electrode 32 is a flat electrode that radiates a high-frequency signal transmitted from the mounting structure 1 as a radio wave.

[0053] The radiation electrode 32 is provided on the dielectric 10 constituting the mounting structure 1, and includes a feed point 321 connected to the second line 12 via a connecting conductor (not shown), and a ground point 322 connected to the ground electrode 14 via a connecting conductor (not shown). The stub 13 is spaced a predetermined distance from the radiation electrode 32 and does not affect the radiation of high-frequency signals by the radiation electrode 32.

[0054] When the radiation electrode 32 is viewed from the Z-axis direction, the length A2 of the radiation electrode 32 in the Y-axis direction plus the length B2 of the radiation electrode 32 in the X-axis direction (A2 + B2) is ¼ of the wavelength of the high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 102. In other words, the length A2 of the radiation electrode 32 in the Y-axis direction plus the length B2 of the radiation electrode 32 in the X-axis direction (A2 + B2) is ¼ of the wavelength of the high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 102.

[0055] The length L of the stub 13 is ¼ of the wavelength of a high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 102. That is, the length L of the stub 13 is ¼ of the wavelength of a high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 102. From another perspective, the length L of the stub 13 is within ±30% of the sum (A2 + B2) of the length A2 of the radiation electrode 32 in the Y-axis direction and the length B2 of the radiation electrode 32 in the X-axis direction.

[0056] In the antenna device 102 configured as described above, a high-frequency signal transmitted from the electrode plate 20 is transmitted from the first line 11 to the second line 12 while suppressing transmission loss, using the first line 11 and the second line 12 of the mounting structure 1 that have been impedance-matched. The high-frequency signal transmitted to the second line 12 is transmitted from the second line 12 to the radiation electrode 32 and is radiated to the outside by the radiation electrode 32.

[0057] This allows the antenna device 102 to receive high-frequency signals from the electrode plate 20 transmitted via the first line 11 and the second line 12 of the mounting structure 1 while minimizing transmission loss and to radiate them efficiently.

[0058] The antenna device 102 according to the second embodiment can be used in the antenna module 200 mounted on the communication device 300, similar to the antenna device 101 according to the first embodiment.

[0059] <Third Embodiment> An antenna device 103 according to a third embodiment will be described with reference to Fig. 6. Regarding the antenna device 103 according to the third embodiment, only the parts that are different from the antenna device 101 according to the first embodiment will be described, and a description of the other parts will be omitted. Like the antenna device 101 according to the first embodiment, the antenna device 103 according to the third embodiment includes the mounting structure 1 described with reference to Figs. 1 and 2. Fig. 6 is a diagram showing the configuration of the antenna device 103 according to the third embodiment.

[0060] 6, the antenna device 103 is a monopole antenna including the mounting structure 1 and a radiation electrode 33. The radiation electrode 33 is a linear electrode that radiates a high-frequency signal transmitted from the mounting structure 1 as a radio wave.

[0061] The radiation electrode 33 is a part of the second line 12, and is provided on the dielectric 10 that constitutes the mounting structure 1. Specifically, the second line 12 constitutes the microstrip line 72 together with the ground electrode 14, but extends longer in the positive direction of the Y axis than the ground electrode 14. In other words, when the main surface 10A of the dielectric 10 is viewed from the Z axis direction, the part of the second line 12 that does not overlap with the ground electrode 14 functions as the radiation electrode 33 (monopole antenna). Note that the radiation electrode 33 is not limited to being a part of the second line 12, and may be formed of a conductor separate from the second line 12.

[0062] The length A3 of the radiation electrode 33 in the Y-axis direction is ¼ of the wavelength of a high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 103. In other words, the length A3 of the radiation electrode 33 in the Y-axis direction is ¼ of the wavelength of a high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 103.

[0063] The length L of the stub 13 is ¼ of the wavelength of a high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 103. In other words, the length L of the stub 13 is ¼ of the wavelength of a high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 103. From another perspective, the length L of the stub 13 is within ±30% of the length A3 of the radiation electrode 33 in the Y-axis direction.

[0064] In the antenna device 103 configured as described above, a high-frequency signal transmitted from the electrode plate 20 is transmitted from the first line 11 to the second line 12 while suppressing transmission loss, using the first line 11 and the second line 12 of the mounting structure 1 that have been impedance-matched. The high-frequency signal transmitted to the second line 12 is radiated to the outside by the radiation electrode 33 that is a part of the second line 12.

[0065] This allows the antenna device 103 to receive high-frequency signals from the electrode plate 20 transmitted via the first line 11 and the second line 12 of the mounting structure 1 while minimizing transmission loss and to radiate them efficiently.

[0066] The antenna device 103 according to the third embodiment can be used in the antenna module 200 mounted on the communication device 300, similar to the antenna device 101 according to the first embodiment.

[0067] <Fourth Embodiment> An antenna device 104 according to a fourth embodiment will be described with reference to Fig. 7. Regarding the antenna device 104 according to the fourth embodiment, only the parts that are different from the antenna device 101 according to the first embodiment will be described, and a description of the other parts will be omitted. Like the antenna device 101 according to the first embodiment, the antenna device 104 according to the fourth embodiment includes the mounting structure 1 described with reference to Figs. 1 and 2. Fig. 7 is a diagram showing the configuration of the antenna device 104 according to the fourth embodiment.

[0068] 7, the antenna device 104 is a dipole antenna including the mounting structure 1 and a radiation electrode 34. The radiation electrode 34 is a flat electrode that radiates a high-frequency signal transmitted from the mounting structure 1 as a radio wave.

[0069] The radiation electrode 34 is provided on the dielectric 10 constituting the mounting structure 1 and includes a first radiation electrode 341 connected to the second line 12 and a second radiation electrode 342 connected to the ground electrode 14 .

[0070] The first radiation electrode 341 extends from the second line 12 in the positive direction of the Y axis, bends at a first bend 341A from the positive direction of the Y axis to the negative direction of the X axis, and extends again in the negative direction of the X axis. The second radiation electrode 342 extends from the ground electrode 14 in the positive direction of the Y axis, bends at a second bend 342A from the positive direction of the Y axis to the positive direction of the X axis on the side opposite to the first radiation electrode 341, and extends again in the positive direction of the X axis. When the main surface 10A of the dielectric 10 is viewed from the Z axis direction, the first bend 341A overlaps with at least a portion of the second bend 342A.

[0071] When the main surface 10A of the dielectric 10 is viewed from the Z-axis direction, the portion of the first radiation electrode 341 extending in the negative direction of the X-axis does not overlap with the ground electrode. The stub 13 is spaced a predetermined distance from the radiation electrode 34 and does not affect the radiation of high-frequency signals by the radiation electrode 34.

[0072] The length A41 of the first radiation electrode 341 in the X-axis direction, which is bent at the first bend 341A and extends in the negative direction of the X-axis, is ¼ of the wavelength of a high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 104. In other words, the length A41 of the first radiation electrode 341 in the X-axis direction is ¼ of the wavelength of a high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 104.

[0073] The length A42 of the second radiation electrode 342 in the X-axis direction, which is bent at the second bend 342A and extends in the positive direction of the X-axis, is ¼ of the wavelength of a high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 104. In other words, the length A42 of the second radiation electrode 342 in the X-axis direction is ¼ of the wavelength of a high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 104.

[0074] That is, the length A41 of the first radiation electrode 341 in the X-axis direction plus the length A42 of the second radiation electrode 342 in the X-axis direction (A41 + A42) is half the wavelength of the high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 104.

[0075] The length L of the stub 13 is ¼ of the wavelength of a high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 104. That is, the length L of the stub 13 is ¼ of the wavelength of a high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 104. From another perspective, the length L of the stub 13 is within ±30% of half the length (A41 + A42) obtained by adding the length A41 of the first radiation electrode 341 in the X-axis direction and the length A42 of the second radiation electrode 342 in the X-axis direction.

[0076] In the antenna device 104 configured as described above, a high-frequency signal transmitted from the electrode plate 20 is transmitted from the first line 11 to the second line 12 while suppressing transmission loss, using the first line 11 and the second line 12 of the mounting structure 1 that have been impedance-matched. The high-frequency signal transmitted to the second line 12 is transmitted from the second line 12 to the radiation electrode 34 and is radiated to the outside by the radiation electrode 34.

[0077] This allows the antenna device 104 to receive high-frequency signals from the electrode plate 20 transmitted via the first line 11 and the second line 12 of the mounting structure 1 while minimizing transmission loss and to radiate them efficiently.

[0078] The antenna device 104 according to the fourth embodiment can be used in the antenna module 200 mounted on the communication device 300, similar to the antenna device 101 according to the first embodiment.

[0079] <Fifth Embodiment> An antenna device 105 according to a fifth embodiment will be described with reference to Fig. 8. Regarding the antenna device 105 according to the fifth embodiment, only the parts that are different from the antenna device 101 according to the first embodiment will be described, and the description of the other parts will be omitted. Like the antenna device 101 according to the first embodiment, the antenna device 105 according to the fifth embodiment includes the mounting structure 1 described with reference to Figs. 1 and 2. Fig. 8 is a diagram showing the configuration of the antenna device 105 according to the fifth embodiment. Note that Fig. 8 shows a cross section of the antenna device 105 having an L-shape when viewed from the Z-axis direction.

[0080] 8, the antenna device 105 includes a dielectric 10 extending in the Y-axis direction and a dielectric 50 extending in the Z-axis direction perpendicular to the dielectric 10. The cross section of the antenna device 105 has a substantially L-shaped cross section formed by the dielectric 10 and the dielectric 50. A SiP (System in Package) module 60 incorporating an RFIC 120 and a power module IC (not shown) is connected to a main surface 50A of the dielectric 50 of the antenna device 105.

[0081] The antenna device 105 includes a ground electrode 51, a ground electrode 52, a radiation electrode 36, a feeder wiring 61, a feeder wiring 62, and an electrode plate 20 in a dielectric 50. The ground electrodes 51 and 52 are arranged inside the dielectric 50 so as to extend in the X-Z plane. The radiation electrode 36 is connected to the SiP module 60 via the feeder wiring 61 extending in the Y-axis direction. The radiation electrode 36 is a flat electrode that radiates a high-frequency signal transmitted from the SiP module 60 via the feeder wiring 61 as a radio wave, and is arranged inside the dielectric 50 so as to extend in the X-Z plane. The electrode plate 20 is arranged facing the dielectric 10 side and is connected to the SiP module 60 via the feeder wiring 62.

[0082] Antenna device 105 includes mounting structure 1 and radiation electrode 35 mounted on dielectric 10. Main surface 10A of mounting structure 1 faces the side surface of SiP module 60. That is, first line 11 and second line 12 of mounting structure 1 are arranged so as to be perpendicular to main surface 50A of dielectric 50.

[0083] The first line 11 is connected to the electrode plate 20. The radiation electrode 35 is a flat electrode that radiates the high-frequency signal transmitted from the mounting structure 1 as radio waves, and is disposed inside the dielectric 10 so as to extend in the Y-Y plane. The radiation electrode 35 is connected to the second line 12 via a feeder wiring 63 that extends in the Z-axis direction.

[0084] When the radiation electrode 35 is viewed from the Z-axis direction, the length A5 of the radiation electrode 35 in the Y-axis direction is ½ of the wavelength of a high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 105. In other words, the length A5 of the radiation electrode 35 in the Y-axis direction is ½ of the wavelength of a high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 105.

[0085] The length L of the stub 13 is ¼ of the wavelength of a high-frequency signal transmitted within the substrate in the frequency band supported by the antenna device 105. In other words, the length L of the stub 13 is ¼ of the wavelength of a high-frequency signal transmitted by the first line 11 and the second line 12 in the frequency band supported by the antenna device 105. From another perspective, the length L of the stub 13 is within ±30% of ½ of the length A5 of the radiation electrode 35 in the Y-axis direction.

[0086] In the antenna device 105 configured as described above, a high-frequency signal transmitted from the electrode plate 20 is transmitted from the first line 11 to the second line 12 while suppressing transmission loss, using the first line 11 and the second line 12 of the mounting structure 1 that have been impedance-matched. The high-frequency signal transmitted to the second line 12 is transmitted from the second line 12 to the radiation electrode 35 and is radiated to the outside by the radiation electrode 35.

[0087] This allows the antenna device 105 to receive high-frequency signals from the electrode plate 20 transmitted via the first line 11 and the second line 12 of the mounting structure 1 while minimizing transmission loss and to radiate them efficiently.

[0088] <Modifications> The present disclosure is not limited to the above-described embodiment, and various modifications and applications are possible. Modifications that can be applied to the present disclosure will be described below.

[0089] Fig. 9 is a perspective view of a transmission line mounting structure 1A according to a modified example. Fig. 10 is a cross-sectional view of the mounting structure 1A according to the modified example. The mounting structure 1 according to the embodiment includes stub 13, which is an open stub with an open end. However, the mounting structure 1A according to the modified example may include stub 13A, which is a short stub with a short-circuited end.

[0090] Specifically, as shown in Figures 9 and 10, a part of the first line 11 extends in the positive direction of the Y-axis from the connection portion of the connecting conductor 15 and then bends in the positive direction of the X-axis, and the end of the first line 11 is connected to the ground electrode 14 via the connecting conductor 16.

[0091] The length of stub 13A, which is a short stub, is half the wavelength of a high-frequency signal transmitted within a substrate in the frequency band supported by an antenna device including mounting structure 1A. In other words, the length of stub 13A is half the wavelength of a high-frequency signal transmitted by first line 11 and second line 12 in the frequency band supported by the antenna device.

[0092] In this way, the mounting structure of the present disclosure may include the stub 13A, which is a short stub, instead of the stub 13, which is an open stub. However, the length of the stub 13A, which is a short stub, needs to be designed to be longer than the length of the stub 13, which is an open stub. Furthermore, in order to connect the stub 13A to the ground electrode 14, it is also necessary to bend the stub 13A from the Y-axis direction to the X-axis direction. Therefore, when the stub 13A, which is a short stub, is used, the size of the dielectric 10 needs to be larger than when the stub 13, which is an open stub, is used. Therefore, it is preferable that the mounting structure of the present disclosure include the stub 13, which is an open stub, rather than the stub 13A, which is a short stub.

[0093] In the mounting structure 1 according to the embodiment, the first line 11 is provided on the main surface 10A of the dielectric 10, but the first line 11 may be provided in an inner layer of the dielectric 10.

[0094] In the mounting structure 1 according to the embodiment, the first line 11 and the second line 12 have a rectangular parallelepiped shape, but the first line 11 and the second line 12 may have other shapes such as a cylinder. In this case, the cross-sectional dimension (e.g., diameter) of the first line 11 in the Z-axis direction may be designed to be larger than the cross-sectional dimension (e.g., diameter) of the second line 12 in the Z-axis direction.

[0095] In the mounting structure 1 according to the embodiment, the connection conductor 15 has a cylindrical shape, but the connection conductor 15 may have another shape such as a rectangular parallelepiped.

[0096] In the mounting structure 1 according to the embodiment, the stub 13 is part of the first line 11, but the stub 13 may be formed of a conductor separate from the first line 11. However, when the conductor forming the stub 13 and the conductor forming the first line 11 are the same, impedance matching can be achieved more easily than when the conductor forming the stub 13 and the conductor forming the first line 11 are different.

[0097] In the mounting structure 1 according to the embodiment, when the main surface 10A of the dielectric 10 is viewed from the Z-axis direction, the stub 13 completely covers the second line 12 in the width direction (X-axis direction), but the stub 13 may also cover at least a portion of the second line 12 in the width direction (X-axis direction).

[0098] <Aspects> (Item 1) A mounting structure of a transmission line according to one aspect includes a dielectric, a ground electrode provided on the dielectric, a first line provided on the dielectric facing the ground electrode, a second line provided on the dielectric facing the ground electrode between the first line and the ground electrode in a normal direction of the dielectric, a connecting conductor connecting the first line and the second line, and a stub extending from a connection portion of the connecting conductor of the first line and provided on the dielectric facing the ground electrode and the second line. The thickness of the first line in the normal direction is greater than the thickness of the second line in the normal direction. The second line extends in the same direction as the extension of the first line. The stub extends in the extension direction of the second line. When the dielectric is viewed from the normal direction, at least a portion of the stub overlaps with the second line in the extension direction.

[0099] (Item 2) In the mounting structure described in item 1, the first line is provided on a main surface of the dielectric.

[0100] (Item 3) In the mounting structure described in item 1 or 2, the thickness of the stub in the normal direction is the same as the thickness of the first line in the normal direction.

[0101] (4) In the mounting structure according to any one of the first to third paragraphs, the stub is a part of the first line.

[0102] (Item 5) In the mounting structure according to any one of items 1 to 4, when the dielectric is viewed in the normal direction, the width of the stub is wider than the width of the second line.

[0103] (Item 6) In the mounting structure according to any one of items 1 to 5, when the dielectric is viewed in the normal direction, the stub covers the second line in the width direction.

[0104] (Item 7) In the mounting structure described in any one of Items 1 to 6, the impedance of the portion of the second line that does not overlap with the stub in the extension direction is the same as the impedance of the first line.

[0105] (Item 8) In the mounting structure described in any one of Items 1 to 7, the distance between the second line and the stub in the normal direction is the same as the distance between the second line and the ground electrode.

[0106] (Item 9) In the mounting structure according to any one of items 1 to 8, the impedance of the portion of the second line that overlaps with the stub in the extension direction is smaller than the impedance of the first line.

[0107] (10) In the mounting structure according to any one of paragraphs 1 to 9, when the dielectric is viewed in the normal direction, the width of the first line is wider than the width of the second line.

[0108] (Item 11) In the mounting structure described in any one of items 1 to 10, when the dielectric is viewed in the normal direction, the cross-sectional dimension of the connecting conductor is wider than the width of the second line and narrower than the width of the first line.

[0109] (12) In the mounting structure according to any one of the first to 11, the end of the stub opposite to the connection portion is open.

[0110] (Item 13) In the mounting structure described in any one of Items 1 to 12, the length of the stub in the extension direction is ¼ of the wavelength of the high-frequency signal transmitted by the first line and the second line.

[0111] (14th Item) An antenna module according to another aspect includes the mounting structure according to any one of the first to thirteenth items, and a radiation electrode that radiates a high-frequency signal transmitted from the mounting structure.

[0112] (15th Clause) A communication device according to another aspect is equipped with the antenna module according to the 14th clause.

[0113] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0114] REFERENCE SIGNS LIST 1, 1A Mounting structure, 10, 50 Dielectric, 10A, 50A Main surface, 11 First line, 12 Second line, 13, 13A Stub, 14, 51, 52 Ground electrode, 15, 16 Connecting conductor, 20 Electrode plate, 31, 32, 33, 34, 35, 36 Radiation electrode, 60 Module, 61, 62, 63 Power supply wiring, 71, 72 Microstrip line, 73 Strip line, 101, 102, 103, 104, 105 Antenna device, 200 Antenna module, 300 Communication device, 311, 321 Power supply point, 312 Center point, 322 Ground point, 341 First radiation electrode, 341A First bend portion, 342 Second radiation electrode, 342A Second bend portion.

Claims

1. A mounting structure for a transmission line that transmits a signal, comprising: a dielectric; a ground electrode provided on the dielectric; a first line provided on the dielectric facing the ground electrode; a second line provided on the dielectric facing the ground electrode between the first line and the ground electrode in the normal direction of the dielectric; a connecting conductor connecting the first line and the second line; and a stub extending from a connection portion of the connecting conductor on the first line and provided on the dielectric facing the ground electrode and the second line, wherein a thickness of the first line in the normal direction is thicker than a thickness of the second line in the normal direction, the second line extends in the same direction as the extension direction of the first line, and the stub extends in the extension direction of the second line, and when the dielectric is viewed from the normal direction, at least a portion of the stub overlaps with the second line in the extension direction.

2. The mounting structure according to claim 1, wherein the first line is provided on a main surface of the dielectric body.

3. The mounting structure according to claim 1 or 2, wherein the thickness of the stub in the normal direction is the same as the thickness of the first line in the normal direction.

4. A mounting structure according to any one of claims 1 to 3, wherein the stub is a part of the first line.

5. A mounting structure according to any one of claims 1 to 4, wherein when the dielectric is viewed from the normal direction, the width of the stub is wider than the width of the second line.

6. A mounting structure according to any one of claims 1 to 5, wherein when the dielectric is viewed from the normal direction, the stub covers the second line in the width direction.

7. A mounting structure as described in any one of claims 1 to 6, wherein the impedance of the portion of the second line that does not overlap with the stub in the extension direction is the same as the impedance of the first line.

8. A mounting structure according to any one of claims 1 to 7, wherein the distance between the second line and the stub in the normal direction is the same as the distance between the second line and the ground electrode.

9. A mounting structure according to any one of claims 1 to 8, wherein the impedance of a portion of the second line that overlaps with the stub in the extension direction is smaller than the impedance of the first line.

10. A mounting structure according to any one of claims 1 to 9, wherein when the dielectric is viewed from the normal direction, the width of the first line is wider than the width of the second line.

11. A mounting structure described in any one of claims 1 to 10, wherein, when the dielectric is viewed from the normal direction, the cross-sectional dimension of the connecting conductor is wider than the width of the second line and narrower than the width of the first line.

12. The mounting structure according to any one of claims 1 to 11, wherein the end of the stub opposite the connection portion is open.

13. A mounting structure according to any one of claims 1 to 12, wherein the length of the stub in the extension direction is 1 / 4 of the wavelength of a high-frequency signal transmitted by the first line and the second line.

14. An antenna module comprising: a mounting structure according to any one of claims 1 to 13; and a radiation electrode that radiates a high-frequency signal transmitted from the mounting structure.

15. A communication device equipped with the antenna module according to claim 14.

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