Multilayer substrate

Abstract

According to the present invention, a multilayer body (12) has a structure in which a plurality of insulator layers (14a to14f) are stacked along the Z-axis. When viewed in the negative direction of the Z-axis, a first ground conductor layer (28) overlaps with a radiation conductor layer (16), while being positioned on the more negative side of the Z-axis than the radiation conductor layer. When viewed in the negative direction of the Z-axis, second ground conductor layers (30a to 30d) do not overlap with the radiation conductor layer, while being positioned on the more positive side of the Z-axis than the first ground conductor layer. When viewed in the negative direction of the Z-axis, no ground conductor layer other than the first ground conductor layer is present between the radiation conductor layer and the second ground conductor layers. A current path is connected to the radiation conductor layer. A branched conductor layer (22) is branched from the current path, and is positioned on the more negative side of the Z-axis than the second ground conductor layers. When viewed in the negative direction of the Z-axis, at least a part of the branched conductor layer overlaps with the second ground conductor layers.

Description

[Technical Field]

[0001] The present invention relates to a multilayer substrate. [Background technology]

[0002] A known example of a conventional invention relating to a multilayer substrate is the antenna module described in Patent Document 1. This antenna module includes a ground electrode, a feed element, a feed line, and a first stub. The ground electrode and the feed element form a patch antenna. The feed line transmits a high-frequency signal to a first feed point of the feed element. The first stub branches off from the feed line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 145392 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in the antenna module described in Patent Document 1, there is a demand for suppressing coupling between the first stub and the feed element.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer substrate capable of suppressing coupling between branch conductor layers and radiation conductor layers. [Means for solving the problem]

[0006] A multilayer substrate according to one embodiment of the present invention comprises: The antenna includes a laminate, a radiation conductor layer, a first ground conductor layer, a second ground conductor layer, a current path, and a branch conductor layer, the laminate has a structure in which a plurality of insulating layers are laminated along the Z axis, the radiating conductor layer is provided on the laminate, the first ground conductor layer is provided on the laminate, overlaps with the radiation conductor layer when viewed in the negative direction of the Z axis, and is located on the negative side of the Z axis with respect to the radiation conductor layer; the second ground conductor layer is provided on the laminate, does not overlap the radiation conductor layer when viewed in the negative direction of the Z axis, and is located on the positive side of the Z axis with respect to the first ground conductor layer; When viewed in the negative direction of the Z axis, there is no ground conductor layer other than the first ground conductor layer between the radiation conductor layer and the second ground conductor layer, the current path is provided in the laminate and connected to the radiation conductor layer; the branch conductor layer is provided in the laminate, is located on the negative side of the Z axis relative to the second ground conductor layer, and branches off from the current path; When viewed in the negative direction of the Z axis, at least a portion of the branched conductor layer overlaps with the second ground conductor layer. [Effects of the Invention]

[0007] According to the multilayer substrate of the present invention, coupling between the branch conductor layer and the radiation conductor layer can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an exploded perspective view of a multilayer substrate 10. As shown in FIG. [Figure 2] FIG. 2 is an exploded perspective view of the multilayer substrate 10a. [Figure 3] FIG. 3 is an exploded perspective view of the multilayer substrate 10b. [Figure 4] FIG. 4 is an exploded perspective view of the multilayer substrate 10c. [Figure 5] FIG. 5 is an exploded perspective view of the multilayer substrate 10d. [Figure 6] FIG. 6 is a rear view of the multilayer substrate 10d. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Embodiment) [Structure of multilayer substrate 10] The structure of a multilayer substrate 10 according to one embodiment of the present invention will be described below with reference to the drawings. FIG.

[0010] In the following, the stacking direction of the laminate 12 is parallel to the up-down axis. The up-down axis coincides with the Z axis. The upward direction is the positive direction of the Z axis. The downward direction is the negative direction of the Z axis. When looking at the laminate 12 downward, two sides of the laminate 12 extend along the left-right axis. When looking at the laminate 12 downward, the remaining two sides of the laminate 12 extend along the front-rear axis. The left-right axis is perpendicular to the up-down axis. The front-rear axis is perpendicular to the up-down axis and the left-right axis. Note that the definitions of directions in this specification are merely examples. Therefore, the directions in this specification do not necessarily coincide with the directions when the multilayer substrate 10 is actually used.

[0011] The multilayer substrate 10 is used in, for example, a wireless communication terminal such as a smartphone. As shown in Fig. 1, the multilayer substrate 10 includes a laminate 12, a radiation conductor layer 16, a first ground conductor layer 28, second ground conductor layers 30a to 30d, a current path R, and a branch conductor layer 22.

[0012] The laminate 12 has a plate shape. As shown in FIG. 1, the laminate 12 has a rectangular shape when viewed from below. The laminate 12 has a structure in which the insulating layers 14a to 14f are stacked along a vertical axis (Z axis). The insulating layers 14a to 14f are arranged in this order from top to bottom. The insulating layers 14a to 14f are made of a thermoplastic resin such as polyimide or liquid crystal polymer. Adjacent insulating layers 14a to 14f are fused together. The laminate 12 is flexible.

[0013] The radiating conductor layer 16 emits and / or receives a high-frequency signal. The radiating conductor layer 16 is provided on the laminate 12. In this embodiment, the radiating conductor layer 16 is located on the upper main surface of the insulating layer 14a. As shown in FIG. 1, the radiating conductor layer 16 has a rectangular shape when viewed from below. As shown in FIG. 1, the radiating conductor layer 16 has two sides extending along the front-rear axis and two sides extending along the left-right axis when viewed from below.

[0014] As shown in FIG. 1, the first ground conductor layer 28 is provided on the laminate 12. More specifically, the first ground conductor layer 28 is located below the radiating conductor layer 16 (on the negative side of the Z axis). The first ground conductor layer 28 is provided on the lower main surface of the insulator layer 14f. As shown in FIG. 1, the first ground conductor layer 28 has a rectangular shape when viewed from below. The first ground conductor layer 28 covers substantially the entire lower main surface of the insulator layer 14f. As a result, the first ground conductor layer 28 overlaps with the radiating conductor layer 16 when viewed from below (in the negative direction of the Z axis). The first ground conductor layer 28 is connected to a ground potential. As a result, the radiating conductor layer 16 and the first ground conductor layer 28 form a patch antenna.

[0015] 1, the second ground conductor layers 30a to 30d are provided on the laminate 12. More specifically, the second ground conductor layers 30a to 30d are located above (on the positive side of the Z axis) the first ground conductor layer 28. In this embodiment, the second ground conductor layers 30a to 30d are located on the upper main surfaces of the insulator layers 14a to 14d, respectively.

[0016] When viewed downward (negative direction of the Z axis), the second ground conductor layers 30a to 30d have a ring shape surrounding the radiation conductor layer 16. The outer and inner edges of the second ground conductor layers 30a to 30d have a rectangular shape with two sides extending along the front-rear axis and two sides extending along the left-right axis. As a result, the second ground conductor layers 30a to 30d do not overlap with the radiation conductor layer 16 when viewed downward (negative direction of the Z axis).

[0017] However, when viewed from below, the second ground conductor layers 30a to 30d are located near the radiation conductor layer 16. Specifically, when viewed from below (negative direction of the Z axis), no ground conductor layers other than the first ground conductor layer 28 exist between the radiation conductor layer 16 and the second ground conductor layers 30a to 30d. The second ground conductor layers 30a to 30d are connected to the ground potential.

[0018] A high-frequency signal is transmitted through the current path R. The current path R is formed by a conductor connecting the external electrode 24 and the radiation conductor layer 16. The current path R is provided in the laminate 12. The current path R is connected to the radiation conductor layer 16. The current path R includes the signal conductor layer 20 and interlayer connection conductors v1 and v2.

[0019] The signal conductor layer 20 is provided on the laminate 12. The signal conductor layer 20 is located below the radiation conductor layer 16 (negative side of the Z axis). The signal conductor layer 20 is located above the first ground conductor layer 28 (positive side of the Z axis). In this embodiment, the signal conductor layer 20 is located on the upper main surface of the insulator layer 14e. As a result, the distance D1 between the signal conductor layer 20 and the first ground conductor layer 28 on the vertical axis (Z axis) is shorter than the distance D2 between the signal conductor layer 20 and the radiation conductor layer 16 on the vertical axis (Z axis).

[0020] The signal conductor layer 20 includes a first portion 20a and a second portion 20b. The first portion 20a extends along the front-rear axis. The second portion 20b extends along the left-right axis. When viewed from below, the front end of the first portion 20a overlaps with the radiation conductor layer 16. The rear end of the first portion 20a is connected to the right end of the second portion 20b.

[0021] 1, the external electrode 24 is provided on the lower main surface of the insulator layer 14f. The external electrode 24 is not in contact with the first ground conductor layer 28. Therefore, the external electrode 24 is located within an opening provided in the first ground conductor layer 28. When viewed from below, the external electrode 24 overlaps with the left end of the second portion. A high-frequency signal is input to or output from the external electrode 24.

[0022] The interlayer connection conductor v1 electrically connects the radiation conductor layer 16 and the signal conductor layer 20. More specifically, the interlayer connection conductor v1 penetrates the insulating layers 14a to 14d along the up-down axis. The upper end of the interlayer connection conductor v1 contacts the radiation conductor layer 16 at the feeding point P1. The lower end of the interlayer connection conductor v1 contacts the front end of the first portion 20a.

[0023] The interlayer connection conductor v2 electrically connects the signal conductor layer 20 and the external electrode 24. More specifically, the interlayer connection conductor v2 penetrates the insulating layers 14e and 14f along the vertical axis. The upper end of the interlayer connection conductor v2 contacts the left end of the second portion 20b. The lower end of the interlayer connection conductor v2 contacts the external electrode 24.

[0024] The interlayer connection conductors v3 to v5 electrically connect the first ground conductor layer 28 and the second ground conductor layers 30a to 30d. More specifically, the interlayer connection conductors v3 to v5 penetrate the insulator layers 14a to 14f along the up-down axis. The upper ends of the interlayer connection conductors v3 to v5 contact the second ground conductor layer 30a. The lower ends of the interlayer connection conductors v3 to v5 contact the first ground conductor layer 28. Furthermore, the middle portions of the interlayer connection conductors v3 to v5 contact the second ground conductor layers 30b to 30d.

[0025] The branch conductor layer 22 is provided on the laminate 12. The branch conductor layer 22 is located below (on the negative side of the Z axis) the second ground conductor layers 30a to 30d. In this embodiment, the branch conductor layer 22 is located on the upper main surface of the insulator layer 14e. The branch conductor layer 22 branches off from the current path R. More specifically, the branch conductor layer 22 extends rightward from the rear end of the first portion 20a and the right end of the second portion 20b. Therefore, when viewed from below, the branch conductor layer 22 has a linear shape. When viewed from below (the negative side of the Z axis), at least a portion of the branch conductor layer 22 overlaps with the second ground conductor layers 30a to 30d. In this embodiment, when viewed from below, the entire branch conductor layer 22 overlaps with the second ground conductor layers 30a to 30d. Therefore, when viewed downward (negative direction of the Z axis), the connection portion between the branch conductor layer 22 and the current path R overlaps with the second ground conductor layers 30a to 30d. However, when viewed downward (negative direction of the Z axis), the branch conductor layer 22 does not overlap with the radiation conductor layer 16. Such a branch conductor layer 22 is an open stub. Therefore, the branch conductor layer 22 is not connected to any conductor layer other than the signal conductor layer 20.

[0026] The radiation conductor layer 16, signal conductor layer 20, branch conductor layer 22, external electrode 24, first ground conductor layer 28, and second ground conductor layers 30a-30d are formed by patterning metal foil attached to the upper or lower principal surfaces of the insulator layers 14a-14f. The metal foil is, for example, copper foil. The interlayer connection conductors v1-v5 are formed by filling through holes that pass through the insulator layers 14a-14f along the vertical axis with conductive paste and solidifying the conductive paste by applying heat and pressure.

[0027] [effect] The multilayer substrate 10 can suppress coupling between the branch conductor layer 22 and the radiating conductor layer 16. More specifically, when viewed from below, at least a portion of the branch conductor layer 22 overlaps with the second ground conductor layers 30a to 30d. This positions the second ground conductor layers 30a to 30d between the radiating conductor layer 16 and the branch conductor layer 22. As a result, the multilayer substrate 10 can suppress coupling between the branch conductor layer 22 and the radiating conductor layer 16.

[0028] In this embodiment, when viewed from below, the connection portions between the branch conductor layer 22 and the current path R overlap with the second ground conductor layers 30a to 30d. This makes it possible to more effectively suppress coupling between the branch conductor layer 22 and the radiation conductor layer 16.

[0029] In this embodiment, the entire branch conductor layer 22 overlaps with the second ground conductor layers 30a to 30d when viewed from below, which makes it possible to more effectively suppress coupling between the branch conductor layer 22 and the radiation conductor layer 16.

[0030] In this embodiment, when viewed from below, the branch conductor layer 22 does not overlap with the radiating conductor layer 16. This makes it possible to more effectively suppress coupling between the branch conductor layer 22 and the radiating conductor layer 16.

[0031] In this embodiment, the branch conductor layer 22 branches off from the current path R. As a result, the branch conductor layer 22 plays a role in matching the characteristic impedance generated in the radiating conductor layer 16 with the characteristic impedance generated in the current path R. As a result, reflection of high-frequency signals at the boundary between the radiating conductor layer 16 and the current path R is suppressed, and loss of high-frequency signals is reduced.

[0032] It is preferable that the branch conductor layer 22 is not far away from the radiating conductor layer 16 for the following reasons. Reflection of the high-frequency signal occurs at the feed point P1. The reflected high-frequency signal is reflected again by the branch conductor layer 22. The reflected wave is radiated as an electromagnetic wave from the radiating conductor layer 16. In this way, in the multilayer substrate 10, the reflected wave is used as an electromagnetic wave of the high-frequency signal.

[0033] Here, if the branch conductor layer 22 is far away from the radiating conductor layer 16, a loss occurs in the reflected wave between the branch conductor layer 22 and the radiating conductor layer 16. Therefore, it is preferable that the branch conductor layer 22 is not far away from the radiating conductor layer 16. This improves the gain of the radiating conductor layer 16.

[0034] In the multilayer substrate 10, the second ground conductor layers 30a to 30d do not overlap the radiation conductor layer 16 when viewed from below, and are located above the first ground conductor layer 28. The radiation pattern and reception pattern of the radiation conductor layer 16 are less likely to spread in the direction approaching the first ground conductor layer 28. This improves the directivity of the radiation pattern and reception pattern of the radiation conductor layer 16.

[0035] In this embodiment, when viewed from below, the second ground conductor layers 30a to 30d have a ring shape surrounding the radiating conductor layer 16. This further improves the directivity of the radiation pattern and reception pattern of the radiating conductor layer 16.

[0036] In the multilayer substrate 10, the distance D1 along the vertical axis (Z-axis) between the signal conductor layer 20 and the first ground conductor layer 28 is shorter than the distance D2 along the vertical axis (Z-axis) between the signal conductor layer 20 and the radiating conductor layer 16. This prevents the signal conductor layer 20 from being coupled to the radiating conductor layer 16.

[0037] (First Modification) A multilayer substrate 10a according to a first modified example will be described below with reference to the drawings. Figure 2 is an exploded perspective view of the multilayer substrate 10a.

[0038] The multilayer substrate 10a differs from the multilayer substrate 10 in the shapes of the second ground conductor layers 30a-30d. More specifically, when viewed from below, the second ground conductor layers 30a-30d have an angular C-shape. When viewed from below, the second ground conductor layers 30a-30d do not have a front side. In this way, when viewed from below, the second ground conductor layers 30a-30d do not have to have a ring shape surrounding the radiation conductor layer 16. The other structure of the multilayer substrate 10a is the same as that of the multilayer substrate 10, so a description thereof will be omitted. The multilayer substrate 10a can achieve the same effects as the multilayer substrate 10.

[0039] (Second Modification) A multilayer substrate 10b according to a second modified example will be described below with reference to the drawings. Figure 3 is an exploded perspective view of the multilayer substrate 10b.

[0040] Multilayer substrate 10b differs from multilayer substrate 10 in the following points. The multilayer substrate 10b does not include the second ground conductor layer 30d. The multilayer substrate 10b further includes an interlayer connection conductor v11. The first portion 20a and the second portion 20b are provided on different insulating layers.

[0041] The first portion 20a is located on the upper main surface of the insulator layer 14d. The second portion 20b is located on the upper main surface of the insulator layer 14e. The interlayer connection conductor v11 penetrates the insulator layer 14d along the vertical axis (Z axis). The upper end of the interlayer connection conductor v11 is in contact with the rear end of the first portion 20a. The lower end of the interlayer connection conductor v11 is in contact with the right end of the second portion 20b and the left end of the branch conductor layer 22. As a result, the branch conductor layer 22 is connected to the interlayer connection conductor v11. The other structure of the multilayer substrate 10b is the same as that of the multilayer substrate 10, and therefore a description thereof will be omitted. The multilayer substrate 10b can achieve the same effects as the multilayer substrate 10.

[0042] (Third Modification) A multilayer substrate 10c according to a third modified example will be described below with reference to the drawings. Figure 4 is an exploded perspective view of the multilayer substrate 10c.

[0043] The multilayer substrate 10c differs from the multilayer substrate 10 in that it further includes an interlayer connection conductor v12. The interlayer connection conductor v12 electrically connects the branch conductor layer 22 and the first ground conductor layer 28. Specifically, the interlayer connection conductor v12 penetrates the insulator layers 14e and 14f along the up-down axis. The upper end of the interlayer connection conductor v12 contacts the right end of the branch conductor layer 22. The lower end of the interlayer connection conductor v12 contacts the first ground conductor layer 28. This makes the branch conductor layer 22 a short stub. The rest of the structure of the multilayer substrate 10c is the same as that of the multilayer substrate 10, so a description thereof will be omitted. The multilayer substrate 10c can achieve the same effects as the multilayer substrate 10.

[0044] (Fourth Modification) A multilayer substrate 10d according to a fourth modified example will be described below with reference to the drawings. Fig. 5 is an exploded perspective view of the multilayer substrate 10d. Fig. 6 is a rear view of the multilayer substrate 10d.

[0045] The multilayer substrate 10d differs from the multilayer substrate 10 in that it has a first section A1 and a second section A2. More specifically, the first section A1 includes a radiation conductor layer 16 and second ground conductor layers 30a-30d. The second section A2 includes a signal conductor layer 20 and a first ground conductor layer 28. The second section A2 has a strip shape extending along the signal conductor layer 20. The first section A1 is not bent. The second section A2 is bent. The other structure of the multilayer substrate 10d is the same as that of the multilayer substrate 10, so a description thereof will be omitted. The multilayer substrate 10d can achieve the same effects as the multilayer substrate 10.

[0046] (Other embodiments) The multilayer substrate according to the present invention is not limited to multilayer substrates 10, 10a to 10d and can be modified within the scope of the invention. Furthermore, the structures of multilayer substrates 10, 10a to 10d may be combined arbitrarily.

[0047] The interlayer connection conductors v11 and v12 may pass through a plurality of insulating layers.

[0048] When viewed from below, the connection portion between the branch conductor layer 22 and the current path R does not necessarily have to overlap with the second ground conductor layers 30a to 30d.

[0049] When viewed from below, a portion of the branch conductor layer 22 may overlap with the second ground conductor layers 30a to 30d.

[0050] When viewed from below, the branch conductor layer 22 may overlap the radiation conductor layer 16 .

[0051] The branched conductor layer 22 does not have to have a linear shape, but may have, for example, a circular or square shape.

[0052] Note that multilayer substrates 10, 10a to 10d may have a feed point P2 in addition to feed point P1. In this case, the electromagnetic field oscillation direction of the high-frequency signal fed at feed point P2 differs from the electromagnetic field oscillation direction of the high-frequency signal fed at feed point P1.

[0053] In addition, a third ground conductor layer may be provided on the signal conductor layer 20 in the second section A2 of the multilayer substrate 10d.

[0054] It is sufficient that the multilayer substrate 10, 10a to 10d includes at least one of the second ground conductor layers 30a to 30d.

[0055] The second ground conductor layers 30a to 30d do not have to have a ring shape surrounding the radiation conductor layer 16. Therefore, each of the second ground conductor layers 30a to 30d may include a plurality of conductor layers arranged at intervals on a circular track surrounding the periphery of the radiation conductor layer 16 when viewed from below.

[0056] The present invention has the following structure.

[0057] (1) a laminate, a radiation conductor layer, a first ground conductor layer, a second ground conductor layer, a current path, and a branch conductor layer; the laminate has a structure in which a plurality of insulating layers are laminated along the Z axis, the radiating conductor layer is provided on the laminate, the first ground conductor layer is provided on the laminate, overlaps with the radiation conductor layer when viewed in the negative direction of the Z axis, and is located on the negative side of the Z axis with respect to the radiation conductor layer; the second ground conductor layer is provided on the laminate, does not overlap the radiation conductor layer when viewed in the negative direction of the Z axis, and is located on the positive side of the Z axis with respect to the first ground conductor layer; When viewed in the negative direction of the Z axis, there is no ground conductor layer other than the first ground conductor layer between the radiation conductor layer and the second ground conductor layer, the current path is provided in the laminate and connected to the radiation conductor layer; the branch conductor layer is provided in the laminate, is located on the negative side of the Z axis relative to the second ground conductor layer, and branches off from the current path; When viewed in the negative direction of the Z axis, at least a portion of the branch conductor layer overlaps with the second ground conductor layer. Multilayer board.

[0058] (2) When viewed in the negative direction of the Z axis, a connection portion between the branch conductor layer and the current path overlaps with the second ground conductor layer. The multilayer substrate according to (1).

[0059] (3) When viewed in the negative direction of the Z axis, the entire branch conductor layer overlaps with the second ground conductor layer. The multilayer substrate according to (1) or (2).

[0060] (4) When viewed in the negative direction of the Z axis, the branch conductor layer does not overlap with the radiation conductor layer. A multilayer substrate according to any one of (1) to (3).

[0061] (5) the current path includes an interlayer connection conductor; the interlayer connection conductor penetrates at least one of the plurality of insulator layers along the Z axis; the branch conductor layer is connected to the interlayer connection conductor; A multilayer substrate according to any one of (1) to (4).

[0062] (6) When viewed in the negative direction of the Z axis, the second ground conductor layer has a ring shape surrounding the radiation conductor layer. A multilayer substrate according to any one of (1) to (5).

[0063] (7) the current path includes a signal conductor layer; the signal conductor layer is provided on the laminate, and is located on the negative side of the Z axis relative to the radiation conductor layer, and on the positive side of the Z axis relative to the first ground conductor layer; a distance in the Z-axis direction between the signal conductor layer and the first ground conductor layer is shorter than a distance in the Z-axis direction between the signal conductor layer and the radiation conductor layer; A multilayer substrate according to any one of (1) to (6).

[0064] (8) The branched conductor layer is an open stub. A multilayer substrate according to any one of (1) to (7).

[0065] (9) The branched conductor layer is a short stub. A multilayer substrate according to any one of (1) to (7). [Explanation of symbols]

[0066] 10,10a~10d: Multilayer board 12: Laminate 14a to 14f: Insulator layers 16: Radiation conductor layer 20: Signal conductor layer 20a: 1st part 20b:Second part 22: Branched conductor layer 24: External electrode 28: First ground conductor layer 30a to 30d: second ground conductor layers A1: First section A2: Second section P1, P2: Power supply points R: Current path v1 to v5, v11, v12: Interlayer connection conductors

Claims

1. a laminate, a radiation conductor layer, a first ground conductor layer, a second ground conductor layer, a current path, and a branch conductor layer; the laminate has a structure in which a plurality of insulating layers are laminated along the Z axis, the radiating conductor layer is provided on the laminate, the first ground conductor layer is provided on the laminate, overlaps with the radiation conductor layer when viewed in the negative direction of the Z axis, and is located on the negative side of the Z axis with respect to the radiation conductor layer; the second ground conductor layer is provided on the laminate, does not overlap the radiation conductor layer when viewed in the negative direction of the Z axis, and is located on the positive side of the Z axis with respect to the first ground conductor layer; When viewed in the negative direction of the Z axis, there is no ground conductor layer other than the first ground conductor layer between the radiation conductor layer and the second ground conductor layer, the current path is provided in the laminate and connected to the radiation conductor layer; the branch conductor layer is provided on the laminate, is located on the negative side of the Z axis relative to the second ground conductor layer, and branches off from the current path; When viewed in the negative direction of the Z axis, at least a portion of the branch conductor layer overlaps with the second ground conductor layer. Multilayer board.

2. When viewed in the negative direction of the Z axis, a connection portion between the branch conductor layer and the current path overlaps with the second ground conductor layer. The multilayer substrate according to claim 1 .

3. When viewed in the negative direction of the Z axis, the entire branch conductor layer overlaps with the second ground conductor layer. The multilayer substrate according to claim 1 or 2.

4. When viewed in the negative direction of the Z axis, the branch conductor layer does not overlap with the radiation conductor layer. The multilayer substrate according to claim 1 or 2.

5. When viewed in the negative direction of the Z axis, the second ground conductor layer has a ring shape surrounding the radiation conductor layer. The multilayer substrate according to claim 1 or 2.

6. the current path includes a signal conductor layer; the signal conductor layer is provided on the laminate, and is located on the negative side of the Z axis relative to the radiation conductor layer, and on the positive side of the Z axis relative to the first ground conductor layer; a distance in the Z-axis direction between the signal conductor layer and the first ground conductor layer is shorter than a distance in the Z-axis direction between the signal conductor layer and the radiation conductor layer; The multilayer substrate according to claim 1 or 2.

7. The branched conductor layer is an open stub. The multilayer substrate according to claim 1 or 2.

8. The branched conductor layer is a short stub. The multilayer substrate according to claim 1 or 2.

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