Multilayer Substrate and Antenna Device Using the Same

Description

Technical Field

[0001] This application relates to a multilayer substrate and an antenna device using the same.

Background Art

[0002] An antenna device is a device that transmits high-frequency signals in the microwave band or millimeter-wave band. The antenna device includes an antenna, an IC (Integrated Circuit) which is a high-frequency signal generator that generates high-frequency signals, and a feeding line. The feeding line connects the antenna and the IC. The IC may be mounted on a substrate surface different from the substrate surface of the dielectric substrate on which the antenna and the feeding line are formed.

[0003] When the IC is mounted on a surface different from the substrate surface of the dielectric substrate on which the antenna is formed, a circuit (converter) for connecting both surfaces is required. A configuration in which a waveguide filled with a dielectric is formed in an inner layer of a multilayer substrate which is a dielectric substrate is disclosed (see, for example, Patent Document 1). In Patent Document 1, the converter has a multilayer substrate, a waveguide filled with a dielectric formed in an inner layer of the multilayer substrate, and a microstrip line, and signals propagate from the waveguide to the microstrip line. By using the disclosed converter, the front and back surfaces of the multilayer substrate can be connected.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] ​By using a waveguide filled with a dielectric formed in the inner layer of a multilayer substrate, the front and back surfaces of the multilayer substrate can be connected. However, when connecting the front and back surfaces of the multilayer substrate according to the shape of the disclosed waveguide, the direction of the signal to be propagated is limited to one specific direction. For example, a signal propagating through a microstrip line provided on the front surface and extending in the X direction, which is one specific direction, will only propagate through a microstrip line provided on the back surface and extending in the X direction via the waveguide. Therefore, when it is desired to change the signal propagation direction by 90 degrees, that is, in the vertical direction, between the front and back surfaces, an additional feeding line for changing the signal propagation direction is required on either the front or the back surface.

[0006] In the additional feeding line, for example, when sufficient space for routing the feeding line cannot be secured, the signal propagation direction has to be changed abruptly. In a feeding line with an abruptly changed signal propagation direction, a discontinuity will occur. At the discontinuity, unwanted radio waves are radiated (hereinafter referred to as unwanted radiation). Unwanted radiation affects the antenna performance and circuit performance depending on its amount. Therefore, there has been a problem that unwanted radiation is generated from the discontinuity. In order to suppress the amount of unwanted radiation, the direction of the line may be changed slowly in the additional feeding line. However, when the direction of the additional feeding line is changed slowly, the space for routing the feeding line increases, so there has been a problem that the area of the circuit provided with the feeding line increases and the multilayer substrate becomes larger. Also, since the area of the circuit increases, there has been a problem that the degree of freedom in the design of the multilayer substrate is reduced.

[0007] Therefore, an object of the present application is to obtain a multilayer substrate with suppressed amount of unwanted radiation, improved miniaturization and design freedom, and an antenna device using the same.

Means for Solving the Problems

[0008] The multilayer substrate disclosed in the present application includes a first dielectric layer having a first conductor layer on one side and a second conductor layer on the other side opposite to the one side, a third conductor layer on one side, and a fourth conductor layer on the other side opposite to the one side, and a second dielectric layer in which the third conductor layer is disposed at a distance from the second conductor layer, one or more intermediate dielectric layers disposed between the second conductor layer and the third conductor layer, and a conductive cylindrical member in contact with the inner peripheral surface of a through hole penetrating a specific portion of the intermediate dielectric layer in the direction from the second conductor layer to the third conductor layer, and a waveguide filled with a dielectric made of a material different from the first dielectric layer, the second dielectric layer, and the intermediate dielectric layer inside the cylindrical member. When there are a plurality of the intermediate dielectric layers, an intermediate conductor layer is provided in a portion between each of the plurality of the intermediate dielectric layers, and the shape of a cross section perpendicular to the direction in which the intermediate dielectric layer in the waveguide is penetrated is a shape in which both corners on one diagonal of a quadrangle are cut off.

[0009] The antenna device disclosed in the present application includes the multilayer substrate disclosed in the present application and an antenna formed on the first conductor layer or the fourth conductor layer.

Advantages of the Invention

[0010] According to the multilayer substrate disclosed in the present application, a first dielectric layer having a first conductor layer on one side and a second conductor layer on the other side opposite to the one side, a third conductor layer on one side, and a fourth conductor layer on the other side opposite to the one side, and a second dielectric layer in which the third conductor layer is disposed at a distance from the second conductor layer, one or more intermediate dielectric layers disposed between the second conductor layer and the third conductor layer, and a conductive cylindrical member in contact with the inner peripheral surface of a through hole penetrating a specific portion of the intermediate dielectric layer, and a dielectric made of a material different from that of the first dielectric layer, the second dielectric layer, and the intermediate dielectric layer is filled inside the cylindrical member. Since the shape of a cross section perpendicular to the direction penetrating the intermediate dielectric layer in the waveguide is a shape in which both corners on one diagonal of a quadrilateral are cut out, the direction of signal propagation can be changed by 90 degrees inside the multilayer substrate, so that an additional conductor pattern for changing the signal propagation direction in either the first conductor layer or the fourth conductor layer becomes unnecessary. Since the additional conductor pattern becomes unnecessary, the multilayer substrate can be miniaturized. In addition, since the additional conductor pattern becomes unnecessary and the circuit area does not increase, the degree of freedom in designing the multilayer substrate can be improved. Further, since a discontinuous portion that abruptly changes the signal propagation direction does not occur, the amount of unnecessary radiation in the multilayer substrate can be suppressed.

[0011] According to the antenna device disclosed in the present application, since it includes the multilayer substrate disclosed in the present application and an antenna connected to the first conductor layer or the fourth conductor layer, by using the multilayer substrate disclosed in the present application for the antenna device, it is possible to suppress the amount of unnecessary radiation and obtain an antenna device with improved miniaturization and design freedom.

Brief Description of the Drawings

[0012]

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Figure 11

Mode for Carrying Out the Invention

[0013] Hereinafter, a multilayer substrate according to an embodiment of the present application and an antenna device using the same will be described with reference to the drawings. In each figure, the same or corresponding members and parts will be described with the same reference numerals.

[0014] Embodiment 1. FIG. 1 is a cross-sectional view showing an outline of a multilayer substrate 11 according to Embodiment 1, a view of the multilayer substrate 11 cut at the cross-sectional position A-A of FIG. 6, FIG. 2 is a schematic diagram showing an outline of an antenna device 100 using the multilayer substrate 11 according to Embodiment 1, FIG. 3 is a cross-sectional view showing an outline of a waveguide 31 of the multilayer substrate 11, a view showing the shape of a cross-section perpendicular to the direction in which the waveguide 31 penetrates, FIG. 4 is a cross-sectional view showing an outline of another waveguide 31 of the multilayer substrate 11, a view showing the shape of a cross-section perpendicular to the direction in which the waveguide 31 penetrates, FIG. 5 is a cross-sectional view showing an outline of another waveguide 32 of the multilayer substrate 11, a view showing the shape of a cross-section perpendicular to the direction in which the waveguide 32 penetrates, FIG. 6 is an exploded perspective view showing an outline of the multilayer substrate 11, FIG. 7 is a view for explaining the operation of the waveguide 31 of the multilayer substrate 11, and FIG. 8 is a view showing transmission line characteristics in the waveguide 31 of the multilayer substrate 11, a view showing the result of electromagnetic field analysis of the reflection coefficient. The X-axis, Y-axis, and Z-axis shown in the figures are three mutually perpendicular axes. The direction parallel to the Y-axis is the Y-axis direction which is the first direction, the direction parallel to the X-axis is the X-axis direction which is the second direction, and the direction parallel to the Z-axis is the Z-axis direction which is the third direction. Among the X-axis directions, the direction indicated by the arrow in the figure is the plus X direction, and the direction opposite to the plus X direction is the minus X direction. The same applies to the Y-axis direction and the Z-axis direction as in the case of the X-axis direction.

[0015] <Antenna device 100> As shown in FIG. 2, the antenna device 100 includes a multilayer substrate 11, a high-frequency signal generator 2, and an antenna 3. The multilayer substrate 11 includes a power supply line 1 that propagates a signal from the high-frequency signal generator 2 to the antenna 3. The antenna device 100 using the power supply line 1 is a device that transmits a high-frequency signal in the microwave band or the millimeter-wave band. Microwaves have a wavelength of 1 mm to 1 m and a frequency of 300 MHz to 300 GHz. Millimeter waves have a wavelength of 1 mm to 10 mm and a frequency of 30 GHz to 300 GHz. The antenna device 100 propagates a signal from the first direction to the second direction.

[0016] The high-frequency signal generator 2 that generates a high-frequency signal is, for example, an IC (Integrated It is provided in a (Circuit). The power supply line 1 connects the high-frequency signal generator 2 and the antenna 3. The high-frequency signal generator 2 is arranged on the multilayer substrate 11, and the antenna 3 is connected to the multilayer substrate 11. The high-frequency signal generator 2 is mounted on a surface different from the substrate surface of the multilayer substrate 11 to which the antenna 3 is connected. The antenna 3 is connected to the first conductor layer or the fourth conductor layer described later. The first conductor layer is provided, for example, on one substrate surface of the multilayer substrate 11, and the fourth conductor layer is provided on the other substrate surface of the multilayer substrate 11. When the antenna 3 is connected to the first conductor layer, the high-frequency signal generator 2 is arranged on the side of the fourth conductor layer, and when the antenna 3 is connected to the fourth conductor layer, the high-frequency signal generator 2 is arranged on the side of the first conductor layer.

[0017] <Multilayer substrate 11> As shown in FIG. 1, the multilayer substrate 11 includes a first dielectric layer 41 having a first conductor layer 21 on one side and a second conductor layer 22 on the other side opposite to the one side, a third conductor layer 23 on one side, and a fourth conductor layer 24 on the other side opposite to the one side. A second dielectric layer 42 in which the third conductor layer 23 is arranged at a distance from the second conductor layer 22, one or more intermediate dielectric layers 43 arranged between the second conductor layer 22 and the third conductor layer 23, and a waveguide 31. The number of intermediate dielectric layers 43 may be one or more. In the present embodiment, the multilayer substrate 11 has five intermediate dielectric layers 43, namely, intermediate dielectric layers 43a, 43b, 43c, 43d, and 43e. When the multilayer substrate 11 has a plurality of intermediate dielectric layers 43, an intermediate conductor layer 25 is provided in a portion between each of the plurality of intermediate dielectric layers 43. In the present embodiment, since the multilayer substrate 11 has five intermediate dielectric layers 43, four intermediate conductor layers 25a, 25b, 25c, and 25d are provided. Each of the conductor layers of the multilayer substrate 11 is, for example, a copper foil. In FIG. 1, the first dielectric layer 41, the second dielectric layer 42, and the intermediate dielectric layer 43 are laminated in the Z direction, and the surfaces on which the respective plate-like layers are laminated are parallel to the X direction and the Y direction.

[0018] The waveguide 31 is a conductive cylindrical member that abuts on the inner peripheral surface of a through-hole penetrating a specific portion of the intermediate dielectric layer 43 in the direction from the second conductor layer 22 to the third conductor layer 23. Inside the cylindrical member, a dielectric 44 made of a material different from that of the first dielectric layer 41, the second dielectric layer 42, and the intermediate dielectric layer 43 is filled. The materials of the first dielectric layer 41, the second dielectric layer 42, and the intermediate dielectric layer 43 are, for example, glass cloth base epoxy resins. The material of the dielectric 44 filled in the waveguide 31 is, for example, epoxy resin. By using different dielectrics for the dielectric 44 inside the waveguide 31 and the dielectric layers, a low-loss dielectric 44 can be provided inside the waveguide 31. By providing a low-loss dielectric 44 inside the waveguide 31, the performance of the waveguide 31 can be improved.

[0019] As shown in FIG. 6, a first conductor pattern 21a is formed on the first conductor layer 21. A fourth conductor pattern 24a is formed on the fourth conductor layer 24. In FIG. 6, only the outer shape of the fourth conductor pattern 24a is shown by a dashed line. In the present embodiment, the power supply line 1 is formed from the first conductor pattern 21a, the fourth conductor pattern 24a, and the waveguide 31. The shape of the first conductor pattern 21a in the present embodiment will be described. The first conductor pattern 21a has an annular line portion 21a1 having a rectangular opening and an input / output terminal portion 21a2 extending in the +Y direction from the annular line portion 21a1. The shape of the opening is not limited to a rectangle, and may be, for example, a polygon other than a rectangle. The input / output terminal portion 21a2 has a multi-stage shape with a varying width at the portion between the annular line portion 21a1 and the end of the first dielectric layer 41. The first conductor pattern 21a has non-connection portions 21a3 that are arranged with a gap from the annular line portion 21a1 at positions on both sides in the X direction and adjacent to the annular line portion 21a1. In the present embodiment, the shape of the non-connection portion 21a3 is a rectangle, but the shape of the non-connection portion 21a3 is not limited to a rectangle and may be, for example, a polygon other than a rectangle.

[0020] The shape of the fourth conductor pattern 24a is the same as that of the first conductor pattern 21a. The fourth conductor pattern 24a has an annular line portion 24a1, an input / output terminal portion 24a2, and a non-connection portion 24a3. However, the extending direction of the input / output terminal portion 24a2 is different from that of the input / output terminal portion 21a2, and the extending direction of the input / output terminal portion 24a2 is the negative X direction. The antenna 3 is connected to the end of the input / output terminal portion 21a2 or the input / output terminal portion 24a2.

[0021] The first conductor pattern 21a is electromagnetically coupled to the second slot 51. The opening of the annular line portion 21a1 is arranged to overlap with the second slot 51 as shown in FIG. 1 when viewed in the Z direction. The fourth conductor pattern 24a is electromagnetically coupled to the third slot 52. The opening of the annular line portion 24a1 is arranged to overlap with the third slot 52 when viewed in the Z direction. If each conductor pattern has a shape that is electromagnetically coupled to each slot, the shape of the conductor pattern is not limited to the shape shown in this embodiment.

[0022] In the second conductor layer 22, as shown in FIG. 6, a second slot 51, which is an open portion of the second conductor layer 22, is formed. In the third conductor layer 23, a third slot 52, which is an open portion of the third conductor layer 23, is formed. The second slot 51 is electromagnetically coupled to the first conductor pattern 21a and the waveguide 31. The second slot 51 is arranged to overlap with the inner portions of the first conductor pattern 21a and the waveguide 31 as shown in FIG. 1 when viewed in the Z direction. The third slot 52 is electromagnetically coupled to the fourth conductor pattern 24a and the waveguide 31. The third slot 52 is arranged to overlap with the inner portions of the fourth conductor pattern 24a and the waveguide 31 when viewed in the Z direction.

[0023] In this embodiment, the second slot 51 and the third slot 52 are formed in a rectangular shape. If each slot has a shape that is electromagnetically coupled to each conductor pattern and the waveguide 31, the shape of the slot is not limited to the shape shown in this embodiment. The slot may have a shape that is a polygon other than a square or a rectangle, or may have a configuration in which a floating conductor pattern is provided in the region inside the slot.

[0024] <Waveguide 31> The configuration of the waveguide 31, which is the main part of the present application, will be described. The shape of the cross-section perpendicular to the direction passing through the intermediate dielectric layer 43 in the waveguide 31 is a shape in which both corners on one diagonal of a rectangle are cut out. The cut-out portions are referred to as cut-out portions 61 and 62. The shape of the cut-out portion of the cross-section perpendicular to the direction passing through the intermediate dielectric layer 43 in the waveguide 31 shown in FIG. 3 is a rectangle. The shapes of the cut-out portions 61 and 62 may be squares, or may be rectangles as shown in FIG. 4. When the rectangle of the cross-section of the waveguide 31 is a square and the cut-out portions 61 and 62 are squares, the cut-out portions 61 and 62 are symmetrically arranged with respect to the diagonal line opposite to the diagonal line provided with the cut-out. When the rectangle of the cross-section of the waveguide 31 is a square and the cut-out portions 61 and 62 are rectangles, the cut-out portions 61 and 62 are asymmetrically arranged with respect to the diagonal line opposite to the diagonal line provided with the cut-out.

[0025] When the shape of the cut-out portion is a rectangle, since the shape of the cut-out is a simple shape, the shape of the waveguide 31 can be easily designed according to the matching conditions of the transmission line characteristics propagating through the waveguide 31. The shape of the cut-out portion is not limited to a rectangle, and according to the matching conditions of the transmission line characteristics, for example, polygons other than rectangles or cut-out shapes that are asymmetric left and right may be used. When the shape of the cut-out portion is other than a rectangle, since the design parameters increase, a waveguide 31 having more precise transmission characteristics can be designed.

[0026] The corners in the square cross-section of the waveguide 31 are right-angled or rounded. The corners in the square cross-section of the waveguide 31 shown in FIG. 3 of the present embodiment are right-angled. When the corners are right-angled, desired transmission characteristics can be easily obtained in the waveguide 31. The corners in the square cross-section of the waveguide 31 are not limited to right-angles. As in the example of another waveguide 32 shown in FIG. 5, the corners in the square cross-section of the waveguide 31 may be rounded, for example, according to the manufacturing conditions of the waveguide 32 or the matching conditions of the transmission line characteristics. Another waveguide 32 has notches 63 and 64. When the corners are rounded, the manufacturability of the waveguide 32 is improved, so that the productivity of the multilayer substrate 11 can be improved.

[0027] The operation of the waveguide 31 provided with the notches 61 and 62 will be described with reference to FIGS. 7(a) to 7(c). The arrows shown in FIGS. 7(a) to 7(c) indicate the directions of the electric fields excited in the second slot 51, the waveguide 31, and the third slot 52, respectively. Here, it will be described on the assumption that after the signal propagates in the minus Y direction of the first conductor pattern 21a, it propagates in the minus X direction of the fourth conductor pattern 24a via the waveguide 31. In the figure, the locations where the electric field is excited are shown by solid lines, the locations where the electric field will be excited later are shown by dashed lines, and other locations are shown by dotted lines.

[0028] The signal propagating in the minus Y direction of the first conductor pattern 21a is electromagnetically coupled to the second slot 51 as shown in FIG. 7(a), and an electric field is excited in the second slot 51 in the minus Y direction (the direction perpendicular to the X axis). The signal electromagnetically coupled to the second slot 51 propagates through the waveguide 31 as shown in FIG. 7(b). The signal propagating through the waveguide 31 propagates while being rotated by 45 degrees with respect to the X axis according to the shape of the waveguide 31. Thereafter, the signal rotated by 45 degrees with respect to the X axis is electromagnetically coupled to the third slot 52 as shown in FIG. 7(c). The signal electromagnetically coupled to the third slot 52 further propagates while being rotated by 45 degrees with respect to the X axis according to the opening shape of the third slot 52. The electric field direction of the signal propagating through the third slot 52 is in a state rotated by 90 degrees with respect to the electric field direction of the signal propagating through the second slot 51, and finally, it is electromagnetically coupled to the fourth conductor pattern 24a and propagates in the minus X direction.

[0029] In this way, since the shape of the cross section perpendicular to the direction penetrating the intermediate dielectric layer 43 in the waveguide 31 is such that both corners on one diagonal of the square are cut out, the direction in which the signal propagates inside the multilayer substrate 11 can be changed by 90 degrees. Since the direction in which the signal propagates inside the multilayer substrate 11 can be changed by 90 degrees, an additional conductor pattern for changing the signal propagation direction is not required in either the first conductor layer 21 provided with the first conductor pattern 21a or the fourth conductor layer 24 provided with the fourth conductor pattern 24a. Since the additional conductor pattern is not required, the multilayer substrate 11 can be miniaturized. In addition, since the additional conductor pattern is not required and the circuit area does not increase, the design freedom of the multilayer substrate 11 can be improved. Also, since a discontinuous portion that abruptly changes the signal propagation direction does not occur, the amount of unnecessary radiation can be suppressed. Further, by using such a multilayer substrate 11 in the antenna device 100, the amount of unnecessary radiation can be suppressed, and an antenna device 100 with improved miniaturization and design freedom can be obtained.

[0030] Regarding the effectiveness of the structure of the waveguide 31 described above, an explanation will be given using FIG. 8 as an example. FIG. 8 is a diagram showing the reflection coefficient with respect to the normalized frequency obtained by electromagnetic field analysis, where the horizontal axis is the normalized frequency and the vertical axis is the reflection coefficient. In the figure, it can be seen that centered on the normalized frequency "1", the reflection coefficient is -20 dB or less within a bandwidth of 8% or more, indicating that good characteristics are achieved. This characteristic means that there is no reflection and propagation occurs at the transmission frequency, and with the structure of the waveguide 31 disclosed in the present application, the signal propagation direction can be changed by 90 degrees with good characteristics. FIG. 8 shows the analysis results for the waveguide 31 having the vertical cross-section shown in FIG. 3, but the effectiveness of the structure of the waveguide 31 is the same for the shapes of other waveguides 31 shown in Embodiment 1 and in other embodiments described later.

[0031] <Dimensions of the waveguide 31> The dimensions of the waveguide 31 will be described. The length of the waveguide 31 in the penetrating direction in the intermediate dielectric layer 43 is a length of one-quarter wavelength of the wavelength of the signal propagating through the waveguide 31. In FIG. 1, the direction of the signal propagating through the waveguide 31 is the plus Z direction or the minus Z direction. The wavelength of the signal propagating through the waveguide 31 is not limited to a length of one-quarter wavelength of the wavelength of the signal propagating through the waveguide 31, and the length may be changed according to preferable transmission line characteristics or design specifications. When the length of the waveguide 31 in the penetrating direction in the intermediate dielectric layer 43 is set to a length of one-quarter wavelength of the wavelength of the signal propagating through the waveguide 31, desired transmission characteristics can be easily obtained in the waveguide 31.

[0032] An example of specific dimensions of the waveguide 31 will be described. When the frequency of the signal propagating through the waveguide 31 is 77 GHz and the relative permittivity of the dielectric 44 is 3, the wavelength in the tube is calculated to be 2.25 mm. In this case, the length of one-quarter wavelength of the wavelength in the tube is 0.56 mm. The waveguide 31 is provided on the multilayer substrate 11 such that the length of the waveguide 31 in the penetrating direction in the intermediate dielectric layer 43 is 0.56 mm. When the length of the waveguide 31 in the penetrating direction is 0.56 mm, the thickness of the multilayer substrate 11 is, for example, 1.1 mm.

[0033] The distance between the opposing sides in the square cross-section of the waveguide 31 is half the wavelength of the signal propagating through the waveguide 31. In FIG. 3, the distance between the opposing sides in the square cross-section of the waveguide 31 is the distance indicated by the arrow. The distance between the opposing sides in the square cross-section of the waveguide 31 is not limited to half the wavelength of the signal propagating through the waveguide 31, and the length may be changed according to preferable transmission line characteristics or design specifications. When the distance between the opposing sides in the square cross-section of the waveguide 31 is set to half the wavelength of the signal propagating through the waveguide 31, desired transmission characteristics can be easily obtained in the waveguide 31.

[0034] <Formation of Waveguide 31> An example of a method for forming the waveguide 31 will be described with respect to the waveguide 31 shown in FIG. 1. First, with five intermediate dielectric layers 43 and four intermediate conductor layers 25 provided, a through-hole penetrating a specific portion of the intermediate dielectric layer 43 is formed by drilling. Next, plating is applied to the inner peripheral surface of the through-hole to form a conductive cylindrical member. The material for the plating is, for example, copper. The conductive cylindrical member and the intermediate conductor layer 25 are electrically connected. Next, the inside of the cylindrical member is filled with a dielectric 44 made of a material different from the first dielectric layer 41, the second dielectric layer 42, and the intermediate dielectric layer 43. The material for the dielectric 44 to be filled is, for example, an epoxy resin. In this way, the portion of the waveguide 31 of the multilayer substrate 11 is formed. After these steps, the second conductor layer 22, the third conductor layer 23, the first dielectric layer 41, the second dielectric layer 42, the first conductor layer 21, and the fourth conductor layer 24 are laminated and provided. Next, a first conductor pattern 21a is provided on the first conductor layer 21, and a fourth conductor pattern 24a is provided on the fourth conductor layer 24, whereby the multilayer substrate 11 is formed.

[0035] As described above, the multilayer substrate 11 according to Embodiment 1 includes a first dielectric layer 41 having a first conductor layer 21 on one side and a second conductor layer 22 on the other side, a second dielectric layer 42 having a third conductor layer 23 on one side and a fourth conductor layer 24 on the other side, with the third conductor layer 23 disposed at a distance from the second conductor layer 22, one or more intermediate dielectric layers 43 disposed between the second conductor layer 22 and the third conductor layer 23, and a conductive cylindrical member in contact with the inner peripheral surface of a through hole penetrating a specific portion of the intermediate dielectric layer 43. A dielectric 44 made of a material different from that of the first dielectric layer 41, the second dielectric layer 42, and the intermediate dielectric layer 43 is filled inside the cylindrical member, and a waveguide 31 is provided. Since the shape of a cross section perpendicular to the direction in which the waveguide 31 penetrates the intermediate dielectric layer 43 is such that both corners on one diagonal of a quadrilateral are cut off, the direction of signal propagation inside the multilayer substrate 11 can be changed by 90 degrees. Therefore, an additional conductor pattern for changing the signal propagation direction in either the first conductor layer 21 or the fourth conductor layer 24 becomes unnecessary. Since the additional conductor pattern becomes unnecessary, the multilayer substrate 11 can be miniaturized. Also, since the additional conductor pattern becomes unnecessary and the circuit area does not increase, the degree of freedom in designing the multilayer substrate 11 can be improved. Further, since a discontinuous portion where the signal propagation direction changes abruptly does not occur, the amount of unnecessary radiation in the multilayer substrate 11 can be suppressed.

[0036] When the length of the waveguide 31 in the penetration direction in the intermediate dielectric layer 43 is a length of one-quarter wavelength of the wavelength of the signal propagating through the waveguide 31, desired transmission characteristics can be easily obtained in the waveguide 31. Also, when the distance between opposite sides of the quadrilateral of the cross section of the waveguide 31 is a length of one-half wavelength of the wavelength of the signal propagating through the waveguide 31, desired transmission characteristics can be easily obtained in the waveguide 31.

[0037] When the corners of the square cross-section of the waveguide 31 are right angles, the desired transmission characteristics can be easily obtained in the waveguide 31. When the corners of the square cross-section of the waveguide 31 have a rounded shape, the desired transmission characteristics can be easily obtained, and the manufacturability of the waveguide 31 is improved, so that the productivity of the multilayer substrate 11 can be improved.

[0038] When the shape of the cut-out portion of the cross-section perpendicular to the direction passing through the intermediate dielectric layer 43 in the waveguide 31 is a square, since the shape of the cut-out is a simple shape, according to the matching conditions of the transmission line characteristics propagating in the waveguide 31, the shape of the waveguide 31 can be easily designed. Further, when the shapes of the cut-out portions 61 and 62 are other than square, since the design parameters increase, a waveguide 31 having more precise transmission characteristics can be designed.

[0039] When the antenna device 100 according to Embodiment 1 includes the multilayer substrate 11 disclosed in the present application and the antenna 3 connected to the first conductor layer 21 or the fourth conductor layer 24, by using the multilayer substrate 11 disclosed in the present application in the antenna device 100, the amount of unnecessary radiation can be suppressed, and an antenna device 100 with reduced size and improved design freedom can be obtained.

[0040] Embodiment 2. The multilayer substrate 12 according to Embodiment 2 will be described. FIG. 9 is a cross-sectional view showing the outline of the multilayer substrate 12 according to Embodiment 2, a view of the multilayer substrate 12 cut at a position equivalent to the A-A cross-sectional position in FIG. 6, FIG. 10 is a cross-sectional view of the multilayer substrate 12 cut at the B-B cross-sectional position in FIG. 9, a cross-sectional view of the portion of the intermediate dielectric layer 43c, and FIG. 11 is a cross-sectional view of the multilayer substrate 12 cut at the C-C cross-sectional position in FIG. 9, a cross-sectional view of the portion of the intermediate conductor layer 25b. The multilayer substrate 12 according to Embodiment 2 has a configuration in which a waveguide 33 is formed by a plurality of via holes 71.

[0041] As shown in FIG. 9, the multilayer substrate 11 includes a first dielectric layer 41 having a first conductor layer 21 on one side and a second conductor layer 22 on the other side opposite to the one side, a third conductor layer 23 on one side and a fourth conductor layer 24 on the other side opposite to the one side, a second dielectric layer 42 in which the third conductor layer 23 is disposed at a distance from the second conductor layer 22, one or more intermediate dielectric layers 43 disposed between the second conductor layer 22 and the third conductor layer 23, and a plurality of via holes 71 penetrating the intermediate dielectric layer 43 in the direction from the second conductor layer 22 to the third conductor layer 23 and surrounding a specific portion of the intermediate dielectric layer 43. The intermediate dielectric layer 43 may be single or plural. In the present embodiment, the multilayer substrate 11 has five intermediate dielectric layers 43, i.e., intermediate dielectric layers 43a, 43b, 43c, 43d, and 43e. When the multilayer substrate 11 has a plurality of intermediate dielectric layers 43, an intermediate conductor layer 25 is provided at least in a portion between each of the plurality of intermediate dielectric layers 43 excluding the waveguide 33 composed of the plurality of via holes 71 and a specific portion. In the present embodiment, since the multilayer substrate 11 has five intermediate dielectric layers 43, four intermediate conductor layers 25a, 25b, 25c, and 25d are provided. Each of the conductor layers of the multilayer substrate 11 is, for example, a copper foil.

[0042] As shown in FIG. 10, a waveguide 33 is formed by a plurality of via holes 71. The shape of a line connecting the plurality of via holes 71 in a cross section perpendicular to the direction in which the waveguide 33 penetrates the intermediate dielectric layer 43 is a shape in which both corners on one diagonal of a quadrilateral are cut off. The cut-off portions are referred to as cutout portions 65 and 66. As shown in FIG. 11, the intermediate conductor layer 25b has an opening 25b1 surrounding a specific portion of the intermediate dielectric layer 43. The portion of the intermediate dielectric layer 43 shown in FIG. 11 is the portion of the intermediate dielectric layer 43c. The intermediate conductor layers 25a, 25c, and 25d also have the same configuration as the intermediate conductor layer 25b. The plurality of via holes 71 are provided so as to overlap a portion around the opening 25b1 surrounding a specific portion of the intermediate dielectric layer 43. The plurality of via holes 71 and the intermediate conductor layer 25 are electrically connected. In FIG. 10, the waveguide 33 is formed by 20 via holes 71, but the number of via holes 71 is not limited to this.

[0043] The waveguide 33 formed by the plurality of via holes 71 has a shape in which the line connecting the plurality of via holes 71 in the vertical cross section is a shape in which both corners on one diagonal of the square are cut out. Therefore, similar to the waveguide 31 of the first embodiment, the direction of signal propagation can be changed by 90 degrees inside the multilayer substrate 12. Since the direction of signal propagation can be changed by 90 degrees inside the multilayer substrate 11, an additional conductor pattern for changing the signal propagation direction is not required in either the first conductor layer 21 provided with the first conductor pattern 21a or the fourth conductor layer 24 provided with the fourth conductor pattern 24a. Since the additional conductor pattern is not required, the multilayer substrate 12 can be miniaturized. In addition, since the additional conductor pattern is not required and the circuit area does not increase, the degree of freedom in designing the multilayer substrate 12 can be improved. Further, since a discontinuous portion that abruptly changes the signal propagation direction does not occur, the amount of unnecessary radiation can be suppressed.

[0044] The waveguide 31 shown in the first embodiment was formed by drilling a through hole penetrating a specific portion of the intermediate dielectric layer 43. Therefore, the shape of the waveguide 31 depended on the size of the drill for forming the through hole, particularly in the corner portions such as the corners of the waveguide 31. In the present embodiment, since the waveguide 33 is formed by the plurality of via holes 71, the shape of the waveguide 33 does not depend on the size of the drill, so that the degree of freedom in designing the shape of the waveguide 33 can be improved.

[0045] As described above, the multilayer substrate 12 according to the second embodiment includes a plurality of via holes 71 that penetrate the intermediate dielectric layer 43 in the direction from the second conductor layer 22 to the third conductor layer 23 and surround a specific portion of the intermediate dielectric layer 43. A waveguide 33 is formed by the plurality of via holes 71. Since the shape of the line connecting the plurality of via holes 71 in a cross section perpendicular to the direction in which the waveguide 33 penetrates the intermediate dielectric layer 43 is a shape in which both corners on one diagonal of a rectangle are cut out, the direction of signal propagation can be changed by 90 degrees inside the multilayer substrate 11. Therefore, an additional conductor pattern for changing the signal propagation direction in either the first conductor layer 21 or the fourth conductor layer 24 becomes unnecessary. Further, since the waveguide 33 is formed by the plurality of via holes 71, the degree of freedom in designing the shape of the waveguide 33 can be improved. Also, since a discontinuous portion that abruptly changes the signal propagation direction does not occur, the amount of unnecessary radiation can be suppressed.

[0046] Moreover, although various exemplary embodiments and examples are described in the present application, the various features, aspects, and functions described in one or more of the embodiments are not limited to the application to a specific embodiment, but are applicable to the embodiments alone or in various combinations. Accordingly, an innumerable number of modifications not illustrated are assumed to be within the scope of the technology disclosed in the present specification. For example, it includes cases where at least one component is modified, added, or omitted, and further cases where at least one component is extracted and combined with components of other embodiments.

Description of Reference Numerals

[0047] 1 Power supply line, 2 High-frequency signal generator, 3 Antenna, 11, 12 Multilayer substrate, 21 First conductor layer, 21a First conductor pattern, 21a1 Annular line portion, 21a2 Input / output terminal portion, 21a3 Non-connected portion, 22 Second conductor layer, 23 Third conductor layer, 24 Fourth conductor layer, 24a Fourth conductor pattern, 24a1 Annular line portion, 24a2 Input / output terminal portion, 24a3 Non-connected portion, 25, 25a, 25b, 25c, 25d Intermediate conductor layer, 25b1 Opening, 31, 32, 33 Waveguide, 41 First dielectric layer, 42 Second dielectric layer, 43, 43a, 43b, 43c, 43d, 43e Intermediate dielectric layer, 44 Dielectric, 51 Second slot, 52 Third slot, 61, 62, 63, 64, 65, 66 Notch portion, 71 Via hole, 100 Antenna device

Claims

1. A first dielectric layer having a first conductor layer on one side and a second conductor layer on the other side opposite to the one side, A second dielectric layer having a third conductor layer on one side and a fourth conductor layer on the other side opposite to the one side, and the third conductor layer is disposed at a distance from the second conductor layer, One or more intermediate dielectric layers disposed between the second conductor layer and the third conductor layer, A conductive cylindrical member in contact with the inner peripheral surface of a through hole penetrating a specific portion of the intermediate dielectric layer in the direction from the second conductor layer to the third conductor layer, and a dielectric made of a material different from the first dielectric layer, the second dielectric layer, and the intermediate dielectric layer is filled inside the cylindrical member, and a waveguide, When there are a plurality of the intermediate dielectric layers, an intermediate conductor layer is provided in a portion between each of the plurality of the intermediate dielectric layers, A multilayer substrate in which a shape of a cross section perpendicular to a direction in which the intermediate dielectric layer is penetrated in the waveguide is a shape in which both corners on one diagonal of a quadrangle are cut out.

2. A first dielectric layer having a first conductor layer on one side and a second conductor layer on the other side opposite to the one side, A second dielectric layer having a third conductor layer on one side and a fourth conductor layer on the other side opposite to the one side, and the third conductor layer is disposed at a distance from the second conductor layer, One or more intermediate dielectric layers disposed between the second conductor layer and the third conductor layer, A plurality of via holes penetrating the intermediate dielectric layer in the direction from the second conductor layer to the third conductor layer and surrounding a specific portion of the intermediate dielectric layer, A waveguide is formed by the plurality of via holes, When there are a plurality of the intermediate dielectric layers, an intermediate conductor layer is provided at least in a portion between each of the plurality of the intermediate dielectric layers excluding the waveguide and the specific portion, A multilayer substrate in which a shape of a line connecting the plurality of via holes in a cross section perpendicular to a direction in which the intermediate dielectric layer is penetrated in the waveguide is a shape in which both corners on one diagonal of a quadrangle are cut out.

3. The multilayer substrate according to claim 1 or 2, wherein a length of the intermediate dielectric layer in a direction of penetration of the waveguide is a length of one-quarter wavelength of a signal propagated through the waveguide.

4. The multilayer substrate according to claim 1 or 2, wherein a distance between opposite sides of the quadrangle is a length of one-half wavelength of a signal propagated through the waveguide.

5. The multilayer substrate according to claim 1 or 2, wherein the corners of the quadrilateral are right angles or rounded shapes.

6. The multilayer substrate according to claim 1 or 2, wherein the shape of the cut-out portion of the cross-section perpendicular to the direction in which the intermediate dielectric layer in the waveguide penetrates is a quadrilateral.

7. An antenna device comprising the multilayer substrate according to claim 1 or 2, and an antenna connected to the first conductor layer or the fourth conductor layer.

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